JP2007026754A - Organic electroluminescent element, exposure device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that variations in the thickness of a light-emitting layer 6 in a light-emitting region LA occur by a level difference of the end part PO on the side for regulating the light-emitting region LA, and distribution of light-emitting brightness in the light-emitting region LA does not become uniform by differences in current density accompanying the occurrence upon installing a pixel regulation layer 8 for regulating the light-emitting region LA between an anode 3 and a cathode 7 when an organic electroluminescent element 1 is formed by a process including a coating process. <P>SOLUTION: This element has the anode 3 into which positive holes are injected, the light-emitting layer 6, the cathode 7 into which electrons are injected, and the pixel regulation layer 8 in which the light-emitting region of the light-emitting layer 6 is regulated by controlling at least one injection out of positive hole injection or electron injection. This element is constituted so that the light-emitting brightness in the light-emitting region LA is made nearly uniform by the pixel regulation layer 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element, an exposure apparatus in which the elements are arranged in a row and used as an exposure light source, and an image forming apparatus equipped with the exposure apparatus.

  An electroluminescent element is a light-emitting device that utilizes electroluminescence of a solid fluorescent substance. Currently, an inorganic electroluminescent element using an inorganic material as a light emitter has been put to practical use, and is used for backlights and flat displays of liquid crystal displays. Some applications are being developed. However, since the voltage required for light emission of the inorganic electroluminescent element is as high as 100 V or more and it is difficult to emit blue light, it is difficult to achieve full color using the three primary colors of RGB. In addition, since the inorganic electroluminescent element has a very large refractive index of the material used as the light emitter, it is strongly affected by total reflection at the interface, and the light extraction efficiency into the air for actual light emission is about 10 to 20%. It is difficult to achieve high efficiency.

  On the other hand, research on electroluminescent devices using organic materials has attracted attention for a long time, and various studies have been made. However, since the luminous efficiency is very low, full-scale practical research has not progressed.

However, in 1987, Kodak's C.I. W. Tang et al. Proposed an organic electroluminescence device having a function-separated stacked structure in which an organic material constituting a light-emitting layer is divided into a hole transport layer and a light-emitting layer, despite a low voltage of 10 V or less. It was revealed that a high luminance of 1000 cd / m ² or more can be obtained (see Non-Patent Document 1). Since then, organic electroluminescence elements have attracted a great deal of attention, and research on organic electroluminescence elements having a similar function-separated layered structure has been actively conducted, especially for the practical application of organic electroluminescence elements. High efficiency and long life, which are indispensable for the research, have been fully studied. In recent years, displays using organic electroluminescence elements have been realized.

  FIG. 13 is a cross-sectional view showing the structure of a conventional organic electroluminescence element.

  Hereinafter, the structure of a conventional general organic electroluminescence element will be described with reference to FIG.

As shown in FIG. 13, the organic electroluminescence element 11 includes, for example, an anode 13 made of a transparent conductive film such as ITO formed on a glass substrate 12 by a sputtering method, a resistance heating vapor deposition method, or the like. N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (hereinafter abbreviated as TPD) formed by resistance heating vapor deposition or the like. ) And the like, an organic material layer 15 made of 8-hydroxyquinoline aluminum (hereinafter abbreviated as Alq ₃ ) formed on the hole transport layer 14 by resistance heating vapor deposition, and the like, and an organic material And a cathode 17 made of a metal film having a thickness of about 100 to 300 nanometers formed on the layer 15 by a resistance heating vapor deposition method or the like. That.

  The hole transport layer 14 and the organic material layer 15 are collectively referred to simply as a light emitting layer 16 for convenience. In this case, the light emitting layer 16 includes, in addition to the hole transport layer 14 and the organic material layer 15, a hole injection layer, an electron injection layer, an electron transport layer, and an electron block layer (both not shown). Also good. The following explanation is also based on this example.

  When a direct current voltage or direct current is applied with the anode 13 of the organic electroluminescence element 11 having the above-described structure as a positive electrode and the cathode 17 as a negative electrode, the organic material layer 15 is positively applied to the organic material layer 15 through the hole transport layer 14. Holes are injected, and electrons are injected from the cathode 17 into the organic material layer 15. In the organic material layer 15 constituting the light emitting layer 16, recombination of holes and electrons occurs, and a light emission phenomenon occurs when excitons generated thereby shift from the excited state to the ground state.

  In such an organic electroluminescence element 11, light emitted from the phosphor in the organic material layer 15 is usually emitted in all directions around the phosphor, and the hole transport layer 14, the anode 13, and the glass substrate 12. Through the light extraction direction (glass substrate 12 direction) to the air. Alternatively, the light is once reflected in the direction opposite to the light extraction direction, reflected by the cathode 17, and emitted to the air via the light emitting layer 16, the anode 13, and the glass substrate 12.

  Furthermore, for the conventional organic electroluminescence element 11, for example, the structures disclosed in Patent Document 1 and Patent Document 2 are known.

  FIG. 14 is a cross-sectional view showing a structural example of a conventional organic electroluminescence element 11. First, the structure of a conventional organic electroluminescence element 11 described in Patent Document 1 will be described with reference to FIG.

  In FIG. 14, reference numeral 18 denotes a pixel regulating layer, which is an insulating film made of polyimide having a thickness of 0.1 μm to 5 μm formed in contact with the anode 13. The pixel restricting layer 18 provides an opening on the anode 13, and the supply of electric charges is controlled by the pixel restricting layer 18. As a result, only the light emitting area LA of the light emitting layer 16 emits light.

  According to Patent Document 1, by providing the pixel restricting layer 18 on the anode 13 as described above, it is possible to avoid a decrease in pattern formation accuracy due to the wraparound of vapor deposition in the manufacturing process of the organic electroluminescence element 11. Further, by making the pixel regulation layer 18 black or dark, the contrast of the organic electroluminescence element 11 is improved, and the pixel regulation layer 18 is formed in a tapered shape at a portion where the pixel regulation layer 18 and the anode 13 are in contact with each other. Thus, it is possible to prevent electrical disconnection due to the step of the pixel regulation layer 18.

  FIG. 15 is a cross-sectional view showing a structural example of a conventional organic electroluminescence element 11. Next, the structure of the conventional organic electroluminescence element described in Patent Document 2 will be described with reference to FIG.

In FIG. 15, reference numeral 18 a denotes a first pixel restricting layer having a taper with respect to the surface of the anode 13, and 18 b denotes a second pixel restricting layer that covers both the first pixel restricting layer 18 a and the anode 13. The second pixel regulating layer 18b is made of an insulating material, but charges are supplied to the light emitting layer 16 by the tunnel effect. In this case, the light emitting region of the light emitting layer 16 is the same as in the case of Patent Document 1. Only LA emits light. In Patent Document 2, the first pixel regulating layer 18a and the second pixel regulating layer 18b covering the first pixel regulating layer 18a and the anode 13 are provided in the organic electroluminescence element 11 due to irregularities and foreign matters on the surface of the glass substrate 12. It is said that it can solve the problem of black spots (dark spots) that do not emit light.
Tan (C.W. Tang), S.A. Vanslyke, "Appl. Phys. Lett." (USA), Vol. 51, 1987, p. 913 Japanese Patent No. 2734464 JP 2002-280186 A

  In the organic electroluminescence element 11, charges injected from the anode 13 and the cathode 17 are recombined in the light emitting layer 16, and as a result, light is emitted, so that the light emitting layer 16 in the region sandwiched between the anode 13 and the cathode 17 is A so-called surface light source is formed. Accordingly, if the thickness of the light emitting layer 16 can be uniformly formed in the region sandwiched between the anode 13 and the cathode 17, the uniformity of the light emission luminance in the light emitting region LA becomes high.

  However, in the case where the conventional organic electroluminescence element 11 is formed by a process including a coating process typified by a spin coat method or the like, the pixel regulation layer 18 that regulates the light emitting region LA is provided between the anode 13 and the cathode 17. As shown in FIG. 14, when the pixel restricting layer 18 is simply provided in contact with the anode 13, the peripheral portion of the light emitting area LA, that is, the end on the side restricting the light emitting area LA in the pixel restricting layer 18 (in FIGS. 14 and 15). In the following description, since this step is referred to as “the end P0 of the pixel regulating layer 18”, a step is generated, and therefore the edge P0 of the pixel regulating layer 18 is generally affected by the capillary phenomenon and the surface tension. The thickness of the light emitting layer 16 is larger than the thickness of the light emitting layer 16 at the center of the light emitting region LA. Due to the difference in current density, the light emission luminance distribution in the light emitting region LA is not uniform, and the light emission luminance at the end P0 of the pixel regulating layer 18 having a low current density is generally compared with the light emission luminance at the central portion of the light emitting region LA. Then it gets lower.

  Further, since the pixel regulation layer 18 is generally made of a transparent material such as polyimide, for example, as shown by LD in FIG. 14, the light generated in the light emitting layer 16 is transmitted through the pixel regulation layer 18 and emitted. This is also one of the factors that the light emission luminance in the light emitting area LA is not uniform. That is, the conventional organic electroluminescence element 11 has a problem that the light emission luminance in the light emitting direction is not uniform. This problem is not solved by simply forming the end portion P0 of the pixel regulating layer 18 in a tapered shape.

  FIG. 16 is an explanatory diagram showing a distribution (in-plane distribution) of light emission luminance in the light emission region LA of the conventional organic electroluminescence element 11. As described above, the distribution (in-plane distribution) of light emission luminance in the light-emitting area LA of the conventional organic electroluminescence element 11 is from the center of the light-emitting area LA to the pixel regulation layer as indicated by the in-plane distribution O in FIG. The light emission luminance decreases toward the 18 end P0. That is, the light emission luminance is not uniform in the light emitting area LA.

  Now, in a device that directly applies to human vision at a clear distance, such as a general display device, to which the organic electroluminescence element 11 is applied, the emission luminance in the light emitting area LA of each organic electroluminescence element 11 is uniform. The property hardly causes a problem (a distribution such as an in-plane distribution O shown in FIG. 16 may be exhibited). Basically, in the display device, it is a problem to make the total amount of light emitted from the light emitting area LA equal among the individual organic electroluminescence elements. For example, by restricting the pixel restriction layer 18 with an isotropic structure, etc. It is possible to reach a practical level.

  However, when considering application of the organic electroluminescence element 11 to an exposure apparatus mounted on an image forming apparatus such as an electrophotographic apparatus, the image forming apparatus displays an electrostatic latent image having a desired shape and potential distribution for each pixel. Therefore, it is necessary to form the light-emitting luminance in the light-emitting region LA of each organic electroluminescence element 11.

  Further, when the thickness of the light emitting layer 16 is not uniform, the current concentrates on the portion where the thickness of the light emitting layer 16 is thin. As a result, the distribution of light emission luminance in the light emitting area LA changes over a long period of time, for example, a dark part becomes relatively bright later. This means that when the organic electroluminescence element 11 is applied to an exposure apparatus, the shape and area of the latent image formed by the exposure apparatus change over time, and it is difficult to obtain a stable image over the long term. It becomes.

Now, the light emission luminance of the organic electroluminescence element 11 in the display device may be at most about 1000 cd / m ² , but the light emission luminance of 10,000 cd / m ² or more is required in an exposure apparatus mounted on an image forming apparatus such as an electrophotographic apparatus. Therefore, deterioration of the organic electroluminescence element 11 becomes a problem. In an image forming apparatus, it is necessary to form a light spot having a predetermined exposure amount (for example, 1.0 microjoule / cm ² ) on the photoconductor in order to form a latent image having a predetermined potential on the photoconductor to be exposed. However, if the light emission luminance in the light emission region LA of the organic electroluminescence element 11 is not uniform, that is, if there is a bright and dark region inside the light emission region LA of each organic electroluminescence element 11, a predetermined exposure amount will be obtained. In this case, a relatively bright area deteriorates quickly. Since the lifetime of the organic electroluminescence element 11 is dominated by the portion where deterioration is most severe, the lifetime of the organic electroluminescence element 11 is substantially shortened when the emission luminance is not uniform compared with the case where the emission luminance is uniform. End up.

  In order to cope with the deterioration of the organic electroluminescence element 11, light amount correction is essential. In the process of correcting the amount of light, the luminance of each organic electroluminescence element 11 is measured by a predetermined light receiving means, and the current value for driving the organic electroluminescence element 11 is controlled based on the measurement result, whereby the organic electroluminescence element is controlled. Even though the overall light emission luminance of 11 can be recovered, it is difficult to recover the original light emission luminance distribution because the degree of deterioration differs for each micro area of the light emitting layer 16 as described above. For this reason, even if the light amount correction is performed, the size of each pixel formed by the image forming apparatus changes, and for example, a defect such as a vertical stripe may appear in the print result.

  Therefore, the present invention controls the structure, shape, surface state or characteristics of the material constituting the pixel regulation layer of the pixel regulation layer of the organic electroluminescence element, so that the organic electroluminescence element has high uniformity of light emission luminance in the light emission region. That is, an organic electroluminescence device having a light emission luminance distribution indicated by an in-plane distribution N in FIG. 16, an exposure apparatus capable of obtaining an electrostatic latent image of a desired size and shape by using this organic electroluminescence device, An object of the present invention is to provide a high-quality image forming apparatus equipped with an exposure apparatus.

  The organic electroluminescence device of the present invention has been made in view of the above problems, and controls the injection of at least one of holes or electrons, an anode for injecting holes, a light emitting layer, a cathode for injecting electrons. And a pixel restricting layer for restricting the light emitting region of the light emitting layer, and this pixel restricting layer is configured so that the light emission luminance in the light emitting region is substantially uniform.

  Thereby, the light emission luminance in the light emitting region of the organic electroluminescence element is made uniform. In other words, the in-plane distribution (light intensity profile) of the light emission luminance of the light emitted from the light emitting area is almost rectangular, and an exposure apparatus using this organic electroluminescence element as a light source has a desired shape and electrostatic potential distribution. Since a latent image can be formed, high image quality of the image forming apparatus can be realized.

  Furthermore, since the deterioration becomes uniform in every region of the light emitting region of each organic electroluminescence element, the life of the organic electroluminescence element can be substantially extended.

  Furthermore, since the light intensity profile is rectangular, the decrease in light emission luminance due to the deterioration of the light emission region proceeds uniformly, and even when the drive current is increased to compensate for the deterioration, the shape of the light intensity profile does not change, and a stable static state is always obtained. An electrostatic latent image can be formed.

  The organic electroluminescence device of the present invention regulates a light emitting region of a light emitting layer by controlling injection of at least one of holes or electrons, an anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and electrons. A pixel restricting layer, and the pixel restricting layer is configured such that the light emission luminance in the light emitting region is substantially uniform. This makes it possible to make the light emission luminance distribution (light quantity profile) of the light emitted from the light emitting region uniform, and to make the current distribution flowing in the organic electroluminescence element uniform, so that uniform light emission can be obtained over a long period of time. it can. Further, since a portion that emits light unnecessarily brightly in order to obtain a desired light emission luminance is not required, the life of the organic electroluminescence element can be extended.

  According to the present invention, the pixel regulation layer is made of an opaque material in the organic electroluminescence element. As a result, light generated by the light emitting layer is not transmitted through the pixel restricting layer, and the light emission luminance in the light emitting region can be made uniform.

  Further, in the present invention, carbon particles are included in the pixel regulation layer in the organic electroluminescence element. As a result, light generated by the light emitting layer is not transmitted through the pixel restricting layer, and the light emission luminance in the light emitting region can be made uniform.

The present invention, when the organic electroluminescent device of the work function of the pixel regulating layer _{W F1,} the work function of the anode and _{W F2,} the pixel regulating layer work function _{W F1} is 2.0 [eV] _{<W F1 <} which is constituted by a metallic material satisfying W _F2. As a result, the thickness of the pixel regulation layer can be reduced, and unevenness of the thickness of the light emitting layer based on the level difference of the pixel regulation layer can be eliminated. Furthermore, the light transmittance of the pixel regulating layer can be made almost zero, and the light emission luminance in the light emitting region can be made uniform.

  In the organic electroluminescence device, the light emission luminance in the light emitting region is substantially uniform depending on the angle formed between the surface of the anode or the cathode and the surface of the pixel regulating layer in contact therewith. This makes it possible to make the light emission luminance distribution (light quantity profile) of the light emitted from the light emitting region uniform, and to make the current distribution flowing in the organic electroluminescence element uniform, so that uniform light emission can be obtained over a long period of time. it can. Further, since a portion that emits light unnecessarily brightly in order to obtain a desired light emission luminance is not required, the life of the organic electroluminescence element can be extended.

  In the organic electroluminescence device, the angle formed between the surface of the anode or the cathode and the surface of the pixel regulating layer in contact with the surface is 3 degrees or more and 45 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be eliminated, and the light emitting layer has a uniform thickness to make the light emission luminance uniform in the light emitting region. be able to.

  In the organic electroluminescence device, the angle formed between the surface of the anode or the cathode and the surface of the pixel regulating layer in contact with the surface is 3 degrees or more and 10 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be eliminated, and the light emitting layer has a uniform thickness to make the light emission luminance uniform in the light emitting region. be able to.

  According to the present invention, in the organic electroluminescence element, the thickness of the pixel regulating layer is set to be equal to or smaller than the width of the light emitting region and 1.5% or more of the width of the light emitting region. As a result, when the light emitting layer is formed by a so-called painting process, even if the light emission luminance in the light emission region becomes non-uniform due to the step of the pixel regulating layer, the non-uniform region of the light emission luminance becomes sufficiently small. This non-uniformity can be substantially ignored.

  Moreover, this invention is comprised by the curved surface which thickness becomes thin, so that the side which controls the light emission area | region in a pixel control layer in an organic electroluminescent element goes to an edge part. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be eliminated, and the light emitting layer has a uniform thickness to make the light emission luminance uniform in the light emitting region. be able to.

  According to the present invention, in the organic electroluminescence element, the side that regulates the light emitting region in the pixel regulating layer is configured with a curved surface that protrudes downward with respect to the surface of the anode or cathode in contact with the pixel regulating layer. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be eliminated, the thickness of the light emitting layer is formed uniformly, and the light emission luminance in the light emitting region is made uniform. be able to.

  According to the present invention, in the organic electroluminescence element, the pixel regulating layer is formed of a solvent that dissolves the light emitting material that constitutes the light emitting layer, or a material that has wettability with respect to the solution in which the light emitting material is dissolved. Accordingly, when the light emitting layer is formed by a so-called coating process, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  In the organic electroluminescence device, the contact angle with the solvent or solution on the side that regulates the light emitting region in the pixel regulating layer is 45 degrees or less. Accordingly, when the light emitting layer is formed by a so-called coating process, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  The present invention also provides an anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and covering the anode or a part of the cathode to control injection of at least one of holes or electrons to control the emission layer. And a pixel restricting layer composed of a plurality of layers for restricting the light emitting region, and the pixel restricting layer is configured so that the light emission luminance in the light emitting region is substantially uniform. As a result, the light emission luminance in the light emitting region can be made uniform, and the current distribution flowing in the organic electroluminescence element becomes uniform, so that uniform light emission can be obtained over a long period of time. Further, since a portion that emits light unnecessarily brightly in order to obtain a desired light emission luminance is not required, the life of the organic electroluminescence element can be extended.

  Moreover, this invention comprises each layer of a pixel control layer with a different material in an organic electroluminescent element, respectively. This makes it possible to separate the functions of each layer of the pixel regulation layer, making it possible to achieve both the insulation that is the original function of the pixel regulation layer and the uniformity of the thickness of the light emitting layer, and forming the light emitting layer by a so-called coating process. In this case, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  The present invention also provides a first pixel regulating layer formed in contact with the anode or cathode in the organic electroluminescence element, and a part of the anode or cathode formed in contact with the first pixel regulating layer. This is composed of a second pixel regulating layer to be covered. As a result, the first pixel regulation layer can be provided with high insulation and the second pixel regulation layer can be separately provided with the function of making the thickness of the light emitting layer uniform. When the layer is formed, the light emitting layer has a uniform thickness, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, an angle formed between the surface of the anode or the cathode and the surface of the first pixel regulating layer in contact with the surface of the organic electroluminescence element is 3 degrees or more and 45 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be indirectly suppressed, and the light emitting layer is formed to have a uniform thickness and the light emission luminance in the light emitting region can be reduced. It can be made uniform.

  According to the present invention, an angle formed between the surface of the anode or the cathode and the surface of the first pixel regulating layer in contact with the surface of the organic electroluminescence element is 3 degrees or more and 10 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or the cathode and the pixel regulating layer can be indirectly suppressed, and the light emitting layer is formed to have a uniform thickness and the light emission luminance in the light emitting region can be reduced. It can be made uniform.

  According to the present invention, in the organic electroluminescence element, the pixel restricting layer is formed by contacting a second pixel restricting layer formed in contact with the anode or the cathode, and a second pixel restricting layer formed in contact with the second pixel restricting layer. The first pixel regulating layer that covers a part of the first pixel regulating layer. As a result, the first pixel regulation layer can be provided with high insulation and the second pixel regulation layer can be separately provided with the function of making the thickness of the light emitting layer uniform. When the layer is formed, the light emitting layer has a uniform thickness, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, an angle formed between the surface of the second pixel regulating layer and the surface of the first pixel regulating layer in contact with the surface is set to 3 degrees or more and 45 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or cathode and the pixel regulating layer can be eliminated, and the light emitting layer has a uniform thickness and the light emission luminance in the light emitting region is uniform. Can be.

  According to the present invention, in the organic electroluminescence element, an angle formed between the surface of the second pixel regulating layer and the surface of the first pixel regulating layer in contact with the surface is 3 degrees or more and 10 degrees or less. As a result, when the light emitting layer is formed by a so-called coating process, the step between the anode or cathode and the pixel regulating layer can be eliminated, and the light emitting layer has a uniform thickness and the light emission luminance in the light emitting region is uniform. Can be.

  According to the present invention, in the organic electroluminescence element, the first pixel restricting layer is made of a photosensitive resin, and the second pixel restricting layer is patterned by the first pixel restricting layer. By patterning the second pixel regulating layer made of another material through the patterned photosensitive resin (which will later become the first pixel regulating layer), a complicated process such as alignment is performed. Therefore, the first pixel restricting layer and the second pixel restricting layer made of a plurality of materials can be easily formed.

  In the organic electroluminescence element, the thickness of the first pixel restricting layer and the thickness of the second pixel restricting layer satisfy the relationship of the thickness of the first pixel restricting layer> the thickness of the second pixel restricting layer. It is comprised as follows. Thereby, sufficient insulation can be imparted to the first pixel regulation layer, and the second pixel regulation layer can be provided with a function of uniformly forming a light emitting layer by eliminating a step from the anode or the cathode, The light emitting layer has a uniform thickness, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, the thickness of the first pixel regulating layer is configured to be not more than the width of the light emitting region and not less than 1.5% of the width of the light emitting region. As a result, when the light emitting layer is formed by a so-called painting process, even if the light emission luminance in the light emission region is nonuniform due to the step formed by the first pixel regulating layer, the region where the light emission luminance is nonuniform is sufficiently small. Therefore, the nonuniformity of the light emission luminance can be substantially ignored.

  According to the present invention, in the organic electroluminescence element, the first pixel regulating layer is made of an opaque material. As a result, light generated by the light emitting layer is not transmitted through the pixel restricting layer, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, the first pixel regulating layer includes carbon particles. As a result, light generated by the light emitting layer is not transmitted through the pixel restricting layer, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, at least the second pixel regulating layer is composed of a solvent that dissolves the light emitting material that constitutes the light emitting layer, or a material that has wettability with respect to a solution in which the light emitting material is dissolved. is there. Accordingly, when the light emitting layer is formed by a so-called coating process, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, at least a contact angle of the second pixel regulating layer with the solvent or solution is set to 45 degrees or less. Accordingly, when the light emitting layer is formed by a so-called coating process, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, the first pixel restriction layer is made of an organic material, and the second pixel restriction layer is made of an inorganic material. By patterning the second pixel regulation layer made of an inorganic material through the patterned photosensitive resin (which will later become the first pixel regulation layer), a complicated process such as alignment is performed. The first pixel restricting layer and the second pixel restricting layer made of a plurality of materials can be easily formed.

  According to the present invention, in the organic electroluminescence element, the first pixel restriction layer is made of an insulating material, and the second pixel restriction layer is made of a conductive material having a predetermined resistance value. As a result, the second pixel regulating layer can be formed in a solid state without being formed in units of organic electroluminescence elements.

  Moreover, this invention sets the resistance value of the surface direction of an electroconductive material to 1 megaohm or more in an organic electroluminescent element. Thereby, current leakage between adjacent organic electroluminescence elements can be prevented.

  According to the present invention, in the organic electroluminescence element, the first pixel restriction layer is made of an insulating material, and the second pixel restriction layer is made of a metal material. Accordingly, it is possible to provide high insulation by the first pixel regulation layer, to reduce the thickness of the second pixel regulation layer, and to eliminate unevenness of the thickness of the light emitting layer based on the level difference of the pixel regulation layer. Furthermore, since the second pixel regulating layer is made of metal, the light transmittance can be made almost zero, and the light emission luminance in the light emitting region can be made uniform.

  According to the present invention, in the organic electroluminescence element, the second pixel restricting layer is made of silicon nitride or aluminum nitride. Since these materials are appropriately subjected to cleaning treatment, ultraviolet treatment, heat treatment, plasma treatment, etc., high wettability is obtained with respect to a solvent that dissolves the light emitting material constituting the light emitting layer or a solution in which the light emitting material is dissolved. It is possible to reduce the thickness of the second pixel regulating layer and ensure wettability with respect to the solvent or solution. Accordingly, when the light emitting layer is formed by a so-called coating process, the thickness of the light emitting layer is uniformly formed, and the light emission luminance in the light emitting region can be made uniform.

  Moreover, this invention is comprised so that an anode may contain the layer comprised by the hole transport material at least in the organic electroluminescent element. Since the unevenness on the anode is absorbed by the layer made of the hole transport material, the thickness of the light emitting layer is formed uniformly, and the light emission luminance in the light emitting region can be made uniform.

  In the organic electroluminescence device of the present invention, the hole transport material is an inorganic oxide or amorphous carbon. The unevenness on the anode is absorbed by the layer formed of these materials, and these materials have sufficient hole transport capability, so that the light emission luminance in the light emitting region can be made more uniform.

  In the organic electroluminescence device according to the present invention, the light emitting layer is made of a material soluble in a solvent. As a result, a uniform coating type method such as a spin coating method or a gap method can be adopted, so that an exposure apparatus using an organic electroluminescence element can be supplied at low cost.

  In the organic electroluminescence device according to the present invention, the light emitting layer is made of a polymer material. As a result, a uniform coating type method such as a spin coating method or a gap method can be adopted, so that an exposure apparatus using an organic electroluminescence element can be supplied at low cost.

  In the present invention, a light emitting layer is formed by spin coating in an organic electroluminescence element. Thereby, an exposure apparatus using an organic electroluminescence element can be supplied at low cost.

  The present invention also includes an anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and a pixel regulation layer for controlling the injection of at least one of holes or electrons to regulate the light emitting region of the light emitting layer. The variation in the thickness of the light emitting layer in the light emitting region regulated by the pixel regulating layer is 20% or less of the average value of the thickness of the light emitting layer in the light emitting region. As a result, the distribution (light intensity profile) of light emission luminance emitted from the light emitting region can be made uniform, and the current distribution flowing in the organic electroluminescence element can be made uniform, and uniform light emission can be obtained over a long period of time. Further, since a portion that emits light unnecessarily brightly in order to obtain a desired light emission luminance is not required, the life of the organic electroluminescence element can be extended.

  The present invention is also an exposure apparatus in which the above-mentioned organic electroluminescence elements are arranged in a row, and the individual organic electroluminescence elements can be controlled to be turned on / off independently. Since the organic electroluminescent element of the present invention has a uniform light emitting layer thickness and uniform light emission luminance, an exposure apparatus to which this is applied can form an electrostatic latent image having a desired size and potential distribution. Furthermore, since the current distribution that flows through the organic electroluminescent element is uniform, the degradation of the light-emitting area of the organic electroluminescent element is uniform, the product life of the exposure apparatus can be extended, and a stable latent image can be formed over a long period of time. An exposure apparatus can be provided. Further, since the organic electroluminescence element of the present invention emits light uniformly in the light emitting region, it is not necessary to emit light brightly in order to obtain a desired light emission luminance, and an exposure apparatus with low power consumption can be realized.

  According to another aspect of the present invention, there is provided an image forming apparatus comprising: the above-described exposure apparatus; a photoreceptor on which an electrostatic latent image is formed by the exposure apparatus; and a developing unit that visualizes the electrostatic latent image formed on the photoreceptor. It is. In the image forming apparatus to which the exposure apparatus of the present invention is applied, it is possible to realize a long-life image forming apparatus because a latent image is stably formed over a long period of time. Further, since the exposure apparatus can be obtained by a simple construction method, the image forming apparatus can be provided at a low price. Further, in the image forming apparatus using the exposure apparatus of the present invention, a desired electrostatic latent image can be obtained, so that a high quality image can always be formed. In addition, the size of the exposure apparatus can be reduced by adopting an organic electroluminescence element as a light source, and a compact image forming apparatus can be realized by mounting this exposure apparatus.

Example 1
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory view showing the structure of an organic electroluminescence element 1 in Example 1 of the present invention. Hereinafter, the structure of the organic electroluminescence element 1 in Example 1 will be described in detail with reference to FIG.

  In FIG. 1, reference numeral 1 denotes an organic electroluminescence element according to the present invention. For the sake of simplicity, the structure is the same as the conventional example, and for example, a drive circuit for driving the anode is omitted from the drawing. The circuit configuration for driving the organic electroluminescence element 1 will be described in detail later.

  2 is a colorless and transparent glass substrate. Examples of the glass substrate 2 include transparent or translucent soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz glass. Inorganic glass such as compound glass can be used.

Other materials can be used as the glass substrate 2, for example, transparent or translucent polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, polyvinyl fluoride, polypropylene, polyethylene, polyacrylate, amorphous polyolefin Polymer materials such as fluororesin polysiloxane and polysilane, and polymer films such as transparent or translucent chalcogenoid glass such as As ₂ S ₃ , As ₄₀ S ₁₀ , S ₄₀ Ge ₁₀ , ZnO, Nb ₂ O, Ta ₂ O ₅ , SiO, Si ₃ N ₄ , metal oxides such as HfO ₂ , TiO ₂ , and materials such as nitride, or when light emitted from the light emitting region is extracted without going through the substrate Opaque silicon, germanium, silicon carbide, gallium arsenide, gallium nitride A semiconductor substrate such as um, or the above-mentioned transparent substrate material containing a pigment or the like, a metal material whose surface is insulated, etc. It can also be used.

  Further, as will be described later, a circuit comprising a resistor, a capacitor, an inductor, a diode, a transistor, and the like for driving the organic electroluminescence element 1 may be formed on the surface of the glass substrate 2 or inside the substrate.

  Further, depending on the application, a material that transmits only a specific wavelength, a material that converts light of a specific wavelength having a light-light conversion function, or the like may be used. The substrate is preferably insulative, but is not particularly limited, and may have conductivity depending on a range or use that does not hinder driving of the organic electroluminescence display element.

Reference numeral 3 denotes an anode made of, for example, ITO (indium tin oxide). As the anode 3, in addition to ITO, IZO (zinc-doped indium oxide), ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO), ZnO, SnO ₂ , In ₂ O ₃ or the like can be used. . The anode 3 can be formed by vapor deposition or the like, but is preferably formed by sputtering.

  Reference numeral 6 denotes a light emitting layer. In the first embodiment, the light emitting layer 6 is formed by adopting a so-called coating process that is simple in process and capable of reducing costs. Specifically, the light emitting layer 6 is formed through a step of applying a solution obtained by dissolving a polymer or low molecular weight organic light emitting material in a solvent such as toluene or xylene, which will be described in detail, by a spin coating method. .

  The polymer organic light-emitting material constituting the light-emitting layer 6 is preferably a material having fluorescence or phosphorescence characteristics in the visible region and good film forming properties. For example, polymers such as polyparaphenylene vinylene (PPV) and polyfluorene are used. A light emitting material or the like can be used.

The light emitting layer 6 may be prepared by dissolving a low molecular weight organic light emitting material in the above-mentioned solvent. As these organic light emitting materials, in addition to Alq ₃ and Be-benzoquinolinol (BeBq ₂ ), 2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) -1,3,4-thiadiazole, 4,4′-bis (5,7-benzyl-2-benzoxazolyl Stilbene, 4,4′-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-) Benzyl-2-benzoxazolyl) thiophine, 2,5-bis ([5-α, α-dimethylbenzyl] -2-benzoxazolyl) thiophene, 2,5-bis [5,7-di- ( 2-Methyl-2-butyl) -2-benzoxazolyl] -3,4 -Diphenylthiophene, 2,5-bis (5-methyl-2-benzoxazolyl) thiophene, 4,4'-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- [2- [4 Benzoxazoles such as-(5-methyl-2-benzoxazolyl) phenyl] vinyl] benzoxazolyl, 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole, 2 , 2 ′-(p-phenylenedivinylene) -bisbenzothiazole and the like, 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyl) Phenyl) vinyl] benzimidazole and other fluorescent whitening agents, tris (8-quinolinol) aluminum, bis (8-quino) Ol) magnesium, bis (benzo [f] -8-quinolinol) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-hydroxy such as 8-quinolinol lithium, tris (5-chloro-8-quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc-bis (8-hydroxy-5-quinolinyl) methane] Metal chelated oxinoid compounds such as quinoline-based metal complexes and dilithium ependridione, 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis (4-Methylstyryl) benzene, distyrylbenzene, 1,4-bis (2 -Styrylbenzene compounds such as ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene, 1,4-bis (2-methylstyryl) 2-methylbenzene, and 2,5-bis (4- Methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2, Distylpyrazine derivatives such as 5-bis [2- (4-biphenyl) vinyl] pyrazine, 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine, naphthalimide derivatives, perylene derivatives, oxadi Azole derivatives, aldazine derivatives, cyclopentadiene derivatives, styrylamine derivatives, coumarin derivatives, aromatic dimethylidin derivatives, etc. It is needed. Furthermore, anthracene, salicylate, pyrene, coronene and the like are also used. Alternatively, a phosphorescent material such as fac-tris (2-phenylpyridine) iridium can be used.

  In Example 1, the light emitting layer 6 is described as a single layer for the sake of convenience in accordance with the conventional example. However, the light emitting layer 6 is sequentially formed from the anode 3 side with the hole transport layer / electron blocking layer / the above-described organic light emitting material ( The light-emitting layer 6 may have a two-layer structure of an electron transport layer / organic light-emitting material (both not shown) in order from the cathode 3 side, or a positive layer in order from the anode 3 side. Hole transport layer / two-layer structure of organic light emitting material (both not shown), or hole injection layer / hole transport layer / electron blocking layer / organic light emitting layer / hole blocking layer / electron transport in order from the anode 3 side A 7-layer structure (both not shown) such as a layer / electron injection layer may be used. Alternatively, the light emitting layer 6 may have a single layer structure made of only the organic light emitting material described above. As described above, the light emitting layer 6 in Example 1 includes a case where the light emitting layer 6 has a multilayer structure having functional layers such as a hole transport layer, an electron block layer, and an electron transport layer. The same applies to other embodiments described later.

As the hole transport layer in the functional layer described above, those having high hole mobility, transparent and good film forming properties are preferable, and besides TPD, porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, and the like Or 1,1-bis {4- (di-P-tolylamino) phenyl} cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis ( P-tolyl) -P-phenylenediamine, 1- (N, N-di-P-tolylamino) naphthalene, 4,4′-bis (dimethylamino) -2-2′-dimethyltriphenylmethane, N, N, N ′, N′-tetraphenyl-4,4′-diaminobiphenyl, N, N′-diphenyl-N, N′-di-m-tolyl-4,4′-diaminobiphe Aromatic tertiary amines such as Nyl, N-phenylcarbazole, 4-di-P-tolylaminostilbene, 4- (di-P-tolylamino) -4 ′-[4- (di-P—) Stilbene compounds such as (tolylamino) styryl] stilbene, triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcones Derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, polysilane aniline copolymers, polymer oligomers, styrylamine compounds, aromatic dimethylidin compounds, Poly-3,4 ethylene glycol Organic materials such as polythiophene derivatives such as xylthiophene (PEDOT), tetradihexylfluorenylbiphenyl (TFB), and poly-3-methylthiophene (PMeT) are used. Further, a polymer-dispersed hole transport layer in which an organic material for a low-molecular hole transport layer is dispersed in a polymer such as polycarbonate is also used. There is also a _{MoO 3, V 2 O 5,} WO 3, TiO 2, SiO, also be an inorganic oxide such as MgO. These hole transport materials can also be used as an electron block material.

  Examples of the electron transport layer in the functional layer described above include oxadiazole derivatives such as 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7), and anthraquinodimethane derivatives. , Diphenylquinone derivatives, polymer materials composed of silole derivatives, bis (2-methyl-8-quinolinolate)-(para-phenylphenolate) aluminum (BAlq), bathopproin (BCP), and the like are used. Moreover, the material which can comprise these electron carrying layers can also be used as a hole block material.

  7 is a cathode in which a metal such as Al is formed by vapor deposition or the like. As the cathode 7 of the organic electroluminescence element, a metal or alloy having a low work function, for example, a metal such as Al, In, Mg, or Ti, a Mg alloy such as a Mg—Ag alloy or a Mg—In alloy, an Al—Li alloy, An Al alloy such as an Al—Sr alloy or an Al—Ba alloy is used. Alternatively, a first electrode layer that is in contact with a metal such as Ba, Ca, Mg, Li, or Cs, or an organic material layer made of a fluoride or oxide of these metals such as LiF or CaO, and Al formed thereon. It is also possible to use a laminated structure of a metal composed of a second electrode made of a metal material such as Ag, In or the like.

  Reference numeral 8 denotes a pixel regulation layer formed in contact with the anode 3. It is desirable that the pixel regulation layer 8 has a high insulating property, is strong against dielectric breakdown, has a good film forming property, and has a high patterning property. As will be described later with reference to a number of examples, the shape, physical properties, structure, and the like of the end portion P0 of the pixel regulation layer 8 of the organic electroluminescence element 1 are controlled to predetermined conditions, so that the organic electroluminescence element 1 It becomes possible to make the light emission luminance in the light emission region LA substantially uniform.

In Example 1, when the pixel restricting layer 8 is a metal with good patterning property and holes are not easily injected into the light emitting layer 6, that is, when the work function of the pixel restricting layer is W _F1 and the work function of the anode is W _F2 , The restriction layer is made of a metal material having a work function W _F1 that satisfies 2.0 [eV] <W _F1 < _WF2 . For example as the anode 3 ITO (work function _W F2 = 5.0 [eV]) In the case of using the greater than the work function is 2.0 [eV] and 5.0 in the numerical range of less than [eV] For example, Cr (4.5 [eV]), Al (4.2 [eV]), Ag (4.2 [eV]), Mg (3.7 [eV]), or the like is used. In terms of the work function value, Li (2.9 [eV]), Na (2.8 [eV]), Ba (2.7 [eV]), K (2.3 [eV]), Cs (2 .1 [eV]) is ideally selected. However, since these metals are highly reactive to water and oxygen, an atmosphere such as dehydration and deoxygenation is sufficient in the manufacturing process of the organic electroluminescence device 1. Need to manage. Further, the pixel restricting layer 8 may be formed in a plurality of layers using these metal materials or other metal materials. However, since the value of the work function on the side in contact with the light emitting layer 6 is important, it is desirable that the metal material described above in the pixel regulation layer 8 is disposed on the side in contact with the light emitting layer 6.

  The pixel regulating layer 8 is formed by, for example, uniformly forming these metal materials by vapor deposition or sputtering, and then patterning, developing, and etching using a photomask. Moreover, you may form by a sputtering method through a mask. The thickness of the pixel regulation layer 8 made of these metals is preferably 0.05 μm or more and 2 μm or less. If the thickness of the pixel regulating layer 8 is less than 0.05 micrometers, a defect is generated in the film, and the probability that a portion that should not originally emit light emits light increases. If the thickness exceeds 2 micrometers, the variation in the thickness of the light emitting layer 6 in the light emitting area LA exceeds 30% with respect to the average thickness due to the step between the anode 3 and the pixel restricting layer 8 at the end P0 of the pixel restricting layer 8. It becomes like this.

  The thickness of the pixel regulating layer 8 is more preferably 0.05 micrometers or more and 0.5 micrometers or less. By setting the thickness of the pixel regulating layer to 0.5 μm or less, the variation in the thickness of the light emitting layer 6 in the light emitting region LA is reduced to 20% or less with respect to the average value of the thickness of the light emitting layer 6. Thus, reducing the variation in the thickness of the light emitting layer 6 directly leads to substantially uniform light emission luminance in the light emitting region LA.

  Here, “making the light emission luminance substantially uniform” means that the shape of the light emission luminance distribution (in-plane distribution) in the light emitting region LA is made close to a rectangle (see the in-plane distribution N shown in FIG. 16). Ideally, it is desirable that the shape of the light emission luminance distribution in the light emitting region LA be a perfect rectangle. However, in reality, it is difficult to form the pixel regulating layer 8 with a thickness of zero, and the light emission luminance at both ends of the light emitting region LA is difficult. Will decline. In addition, when the light emitting layer 6 is formed, the above-described nonuniform coating of the solvent and solution does not become zero, so that complete uniform light emission in the entire light emitting area LA is difficult, and the shape of the in-plane distribution N is a perfect rectangle. Must not. As a guideline for “making the light emission luminance substantially uniform”, the light emission luminance distribution in the light emission region LA has a substantially flat portion at the center of the light emission region LA, and this flat portion is approximately the width of the light emission region LA. If it occupies about 4/5, the luminance distribution has almost no influence on the lifetime of the organic electroluminescence element 1, and can be adopted without any problem as a light source for an exposure apparatus or the like to be described later.

  In addition, since the pixel restricting layer 8 can be made opaque by adopting a metal material as the pixel restricting layer 8, the emitted light does not pass through the pixel restricting layer 8 as described in the conventional example, and the organic electroluminescence element 1 The light emission luminance in the light emission region LA is further uniformized. The effect can be found if the light transmittance of the pixel regulating layer 8 is 50% or less. However, if a metal material is used as the pixel regulating layer 8 as described above, the light transmittance is almost 0%, which is very high. It is effective.

  In order to reduce the light transmittance of the pixel restricting layer 8, it is desirable to use a metal material having a predetermined work function range as the pixel restricting layer 8 as described above. However, the pixel restricting layer 8 is made of resin. In this case, the light transmittance may be reduced by using, for example, polyimide mixed with carbon particles. When carbon particles are mixed, the resistance value of the pixel regulating layer 8 is lowered. Therefore, it is desirable that the thickness of the pixel regulating layer 8 is 2 micrometers which is the above-described upper limit value.

  When the organic electroluminescence element 1 is used as a light source of the exposure apparatus, the light emitted from the organic electroluminescence element 1 is, for example, a wavelength λ = 660 nm in order to match the sensitivity of the photosensitive member 28 (described later, see FIG. 2). Although the wavelength is longer, the pixel regulation layer 8 is mixed with a dye having an absorption spectrum for this wavelength (a dye exhibiting a cyan color for the above wavelength), thereby reducing the above-described resistance value. This can be avoided, and the thickness of the pixel regulation layer 8 can be further reduced.

  Hereinafter, the description will be continued in more detail. When a direct current voltage or direct current is applied between the anode 3 and the cathode 7 of the organic electroluminescence element 1, holes are injected from the anode 3 to the light emitting layer 6, and electrons are injected from the cathode 7 to the light emitting layer 6. As a result, recombination of holes and electrons occurs in the light emitting layer 6, and a light emission phenomenon occurs when excitons generated thereby shift from the excited state to the ground state, and this light emission is the anode 3, the glass substrate 2. Etc. and is emitted into the air. At this time, in the region where the pixel regulating layer 8 is formed (region other than LA in FIG. 1), no charge is injected into the light emitting layer 6 and no light is emitted.

  In general, a region where light is emitted in the organic electroluminescence element 1, a so-called light emitting region LA, is regulated by being a region sandwiched between the anode 3 and the cathode 7. However, when the light emitting area LA is restricted only by the positional relationship between the anode 3 and the cathode 7, it is difficult to form a complicated shape such as a circular shape or a hexagon as the light emitting area LA, and the anode 3 and the cathode 7. If the accuracy of the alignment is poor, there will be inconveniences such as variations in the size of the light emitting area LA. Therefore, a configuration in which the light emitting area LA is regulated by the pixel regulating layer 8 as shown in the first embodiment is used.

  However, as described with reference to the conventional example, in the case where the organic electroluminescence element 1 is formed by a process including a coating process typified by a spin coating method, the light emitting region LA is regulated between the anode 3 and the cathode 7. When the pixel restricting layer 8 is provided, a step is generated at the end P0 of the pixel restricting layer 8. Therefore, the thickness of the light emitting layer 6 and the light emitting region LA at the end P0 of the pixel restricting layer 8 are affected by the capillary phenomenon and the surface tension. The thickness of the light emitting layer 6 in the central portion of each of them will be different. Due to the difference in current density, the distribution of light emission luminance in the light emission region LA is not uniform, and the light emission luminance at the end P0 of the pixel regulating layer 8 having a low current density is generally compared with the light emission luminance at the center of the light emission region LA. Then it gets lower.

  In order to make the light emission luminance in the light emitting area LA uniform, it is necessary to form at least the thickness of the light emitting layer 6 in the light emitting area LA at least.

  Further, since the conventional pixel regulating layer 8 is generally made of a transparent material such as polyimide, the light generated by the light emitting layer 6 is emitted through the pixel regulating layer 8. This is also one of the factors that the light emission luminance in the light emitting area LA is not uniform.

  Further, when the thickness of the light emitting layer 6 is not uniform, the current concentrates on the portion where the thickness of the light emitting layer 6 is thin. As a result, the distribution of light emission luminance in the light emitting area LA changes over a long period of time, for example, a dark part becomes relatively bright later.

  By making the thickness of the light emitting layer 6 in the light emitting region LA uniform, the current distribution flowing in the organic electroluminescent element 1 becomes uniform, and uniform light emission can be obtained over a long period of time. In addition, when the distribution of light emission luminance is not uniform, an area that emits light with a luminance higher than the originally required brightness occurs when attempting to obtain a luminance of a predetermined amount or more at any part of the light emission region LA, and the lifetime of the organic electroluminescence element 1 is increased. However, in the organic electroluminescent element 1 of Example 1, since the light emitting region LA can be uniformly emitted, it is not necessary to emit light unnecessarily brightly in order to obtain a desired light emission luminance. Thus, the organic electroluminescence device 1 can emit light stably.

  As described above, since the thickness of the end portion P0 of the pixel regulation layer 8 is set to 0.05 μm or more and 2 μm or less, a structure such as a step at the end portion P0 of the pixel regulation layer 8 can be reduced. Thus, the organic electroluminescence device 1 in which the thickness of the light emitting layer 6 in the light emitting area LA is uniform can be easily realized, and the light emission luminance distribution of the light emitted from the light emitting area LA can be made uniform. Become.

  In addition, by setting the thickness of the pixel regulation layer 8 to 0.05 μm or more and 2 μm or less, even if a region with uneven light emission luminance is generated, this region is sufficiently smaller than the light emitting region LA. For example, if the size of the light emitting area LA is about 10,000 square micrometers, that is, the size of a pixel having a high definition such as a normal high-definition display or a fine light source of about 250 dpi, the presence of the emission luminance distribution is ignored. be able to.

  Further, it is more desirable that the thickness of the end portion P0 of the pixel regulation layer 8 is 0.05 micrometers or more and 0.5 micrometers or less. When the thickness of the end portion P0 of the pixel regulating layer 8 is reduced to this level, for example, the light emitting area LA has a size of about 2500 square micrometers, that is, an ultra-high-definition light source used for a micro display or an image forming apparatus with about 500 dpi. Even in a very small case such as a pixel with a high definition, the presence of the emission luminance distribution can be ignored.

  In particular, an ultra-high-definition light source used in an image forming apparatus or the like is not a human eye but a photoconductor and the like, and light emission uniformity is required. Therefore, such a high-definition organic electroluminescence element 1 is required. Then, it is desirable that the thickness of the pixel regulation layer 8 be 0.05 μm or more and 0.5 μm or less. When the thickness of the pixel regulation layer 8 is set to 0.05 micrometers or less, the probability of emitting light other than the place where light should be emitted increases due to defects in the pixel regulation layer 8 or the like. It is desirable that the thickness be 0.05 μm or more and 0.5 μm or less.

  Now, as the structure such as a step generated by the pixel regulating layer 8 becomes larger than the area of the light emitting region LA regulated by the pixel regulating layer 8, the non-uniformity of the emission luminance due to the end portion P0 of the pixel regulating layer 8 is increased. The impact of will increase.

  However, in the electrophotographic image forming apparatus described so far, as the size of the light spot irradiated onto the photoconductor (see FIG. 2 in FIG. 2) is reduced, the latent energy distribution in the light spot is reduced. Since the followability of the image potential deteriorates, for example, when realizing a high resolution exceeding 9600 dpi (9600 dpi: 25.4 millimeters / 9600 = 2.6 micrometers) as the pixel size of the exposure apparatus (see FIG. 3), The thickness of the pixel regulating layer 8 may be configured to be less than or equal to the size of the light emitting area LA. Since the lower limit of the thickness of the pixel restricting layer 8 is 0.05 μm as a guide as described above, the ratio of the pixel restricting layer 8 and the pixel size at this time is 0.05 μm / 2.6 μm = about 1.9%.

  When the exposure apparatus (see FIG. 3) realizes a resolution of about 2400 dpi (2400 dpi: 25.4 millimeters / 2400 = 10.5 micrometers), the thickness of the pixel regulation layer 8 is set to the size of the light emitting area LA. What is necessary is just to comprise to the extent which becomes 1/5 (namely, 2.1 micrometers) or less. Since the lower limit of the thickness of the pixel restricting layer 8 is 0.05 μm as a guide as described above, the ratio of the pixel restricting layer 8 and the pixel size at this time is 0.05 μm / 2.1 μm = about 2.4%.

  When the exposure apparatus (see FIG. 3) achieves a resolution of about 1200 dpi (1200 dpi: 25.4 millimeters / 1200 = 21 micrometers), the thickness of the pixel regulation layer 8 is set to 10 minutes the size of the light emitting area LA. It may be configured to be less than 1 (that is, 2.1 micrometers) or less. Since the lower limit of the thickness of the pixel restricting layer 8 is 0.05 μm as a guide as described above, the ratio of the pixel restricting layer 8 and the pixel size at this time is 0.05 μm / 2.1 μm = about 2.4%.

  Regarding the lower limit of the thickness of the pixel regulation layer 8, since the surface of the anode 3 can be smoothed, the ratio between the pixel regulation layer 8 and the pixel size may be about 1.5% or more.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In the above embodiment, the case where the pixel restricting layer 8 is provided to the anode 3 formed on the glass substrate 2 in the organic electroluminescence element 1 to restrict the light emitting region LA has been described. Needless to say, the technical idea of the first embodiment can be similarly applied to a structure in which the pixel regulation layer 8 is provided on the formed cathode 7 to regulate the light emitting area LA.

  FIG. 2 is a block diagram of the exposure apparatus in Embodiment 1 of the present invention. Hereinafter, the structure of the exposure apparatus will be described in detail with reference to FIG.

  In FIG. 2, reference numeral 33 denotes an exposure device mounted on the image forming apparatus, which is a member that forms an electrostatic latent image on the surface of the photoreceptor 28. The configuration and operation of the image forming apparatus will be described in detail later.

  Reference numeral 2 denotes the glass substrate already described. On the surface A of the glass substrate 2, the organic electroluminescence element 1 as a light emitting element, that is, an exposure light source, has a resolution of 600 dpi (dot / inch) in a direction perpendicular to the drawing (main scanning direction). Is formed.

  Reference numeral 71 denotes a lens array in which rod lenses (not shown) made of plastic or glass are arranged in a row, and the light emitted from the organic electroluminescence element 1 formed on the surface A of the glass substrate 2 is erecting at an equal magnification. As an image, the image is guided to the surface of the photoreceptor 28 where a latent image is formed. The positional relationship of the glass substrate 2, the lens array 71, and the photoconductor 28 is adjusted so that one focus of the lens array 71 is the surface A of the glass substrate 2 and the other focus is the surface of the photoconductor 28. . That is, when the distance L1 from the surface A to the surface closer to the lens array 71 and the distance L2 from the other surface of the lens array 71 to the surface of the photosensitive member 28 are set, L1 = L2.

  Reference numeral 72 denotes a relay substrate using a glass epoxy substrate, for example. 73 a is a connector A, 73 b is a connector B, and at least a connector A 73 a and a connector B 73 b are mounted on the relay board 72. The relay substrate 72 temporarily relays image data, light amount correction data, and other control signals supplied from the outside to the exposure apparatus 33 via a cable 76 such as a flexible flat cable, etc., via a connector B 73b, and these signals are glass. Pass to substrate 2.

  Since it is difficult to directly mount the connector on the surface of the glass substrate 2 in consideration of bonding strength and reliability in various environments where the exposure apparatus 33 is placed, the connector A 73a of the relay substrate 72 and the glass are used in the first embodiment. FPC (flexible printed circuit) is adopted as means for connecting to the substrate 2 (not shown; details will be described later), and the glass substrate 2 and FPC are bonded in advance using, for example, ACF (anisotropic conductive film). For example, an ITO (indium tin oxide) electrode formed on the substrate 2 is directly connected.

  On the other hand, the connector B 73b is a connector for connecting the exposure apparatus 33 to the outside. In general, connection by ACF or the like often has a problem of bonding strength, but by providing the connector B 73b for connecting the exposure apparatus 33 on the relay substrate 72 in this way, the interface directly accessed by the user. Sufficient strength can be secured.

  Reference numeral 74a denotes a casing A which is formed by bending a metal plate, for example. An L-shaped portion 75 is formed on the side of the housing A 74 a facing the photoreceptor 28, and the glass substrate 2 and the lens array 71 are disposed along the L-shaped portion 75. By aligning the end surface of the housing A 74a on the photosensitive member 28 side with the end surface of the lens array 71 and further supporting one end of the glass substrate 2 by the housing A 74a, the L-shaped portion 75 of the L-shaped portion 75 is supported. If the molding accuracy is ensured, the positional relationship between the glass substrate 2 and the lens array 71 can be accurately adjusted. As described above, since the casing A 74a is required to have dimensional accuracy, the casing A 74a is preferably made of metal. Further, by making the casing A 74a made of metal, it is possible to suppress the influence of noise on electronic components such as a control circuit formed on the glass substrate 2 and an IC chip surface-mounted on the glass substrate 2. It is.

  74b is a casing B obtained by molding a resin. A notch (not shown) is provided in the vicinity of the connector B 73b of the housing B 74b, and the user can access the connector B 73b from this notch. The image data, the light amount correction data, the control signal such as the clock signal and the line synchronization signal, the driving power source of the control circuit, and the light emitting element are supplied from the outside of the exposure apparatus 33 to the exposure apparatus 33 through the cable 76 connected to the connector B 73b. A driving power source for the organic electroluminescence element is supplied.

  FIG. 3A is a top view of the glass substrate 2 according to the exposure apparatus 33 of Example 1, and FIG. 3B is an enlarged view of the main part thereof. Hereinafter, the configuration of the glass substrate 2 in Example 1 will be described in detail with reference to FIG.

  In FIG. 3, the glass substrate 2 is a rectangular substrate having a thickness of about 0.7 mm and having at least a long side and a short side, and a plurality of organic electroluminescences which are light emitting elements in the long side direction (main scanning direction). Elements 1 are formed in rows. In Example 1, light emitting elements necessary for at least A4 size (210 mm) exposure are arranged in the long side direction of the glass substrate 2, and the long side direction of the glass substrate 2 is 250 mm including the arrangement space of the drive control unit 78 described later. It is said. In the first embodiment, the glass substrate 2 is described as a rectangle for the sake of simplicity. However, a notch is provided in a part of the glass substrate 2 for positioning when the glass substrate 2 is attached to the housing A 74a. May be accompanied by various deformations.

  A drive 78 receives a control signal (a signal for driving the organic electroluminescence element 1 as a light emitting element) supplied from the outside of the glass substrate 2 and controls driving of the organic electroluminescence element 1 based on the control signal. The control unit includes an interface unit that receives a control signal from the outside of the glass substrate 2 and an IC chip (source driver) that controls driving of the light emitting element based on the control signal received through the interface unit, as will be described later. .

  Reference numeral 80 denotes an FPC (flexible printed circuit) as an interface means for connecting the connector A 73a of the relay substrate 72 and the glass substrate 2, and is directly connected to a circuit pattern (not shown) provided on the glass substrate 2 without using a connector or the like. ing. As already described, image data, light amount correction data, control signals such as clock signals and line synchronization signals, drive power for the control circuit, and the organic electroluminescence element 1 that is a light emitting element are supplied to the exposure apparatus 33 from the outside. The drive power is supplied to the glass substrate 2 through the FPC 80 after passing through the relay substrate 72 shown in FIG.

  In the first embodiment, 5120 organic electroluminescence elements 1 as light sources of the exposure apparatus 33 are formed in a row at a resolution of 600 dpi in the main scanning direction, and each organic electroluminescence element 1 is independently described later. Lighting / extinguishing is controlled by the TFT circuit.

  A source driver 81 is supplied as an IC chip for controlling the driving of the organic electroluminescence element 1 and is flip-chip mounted on the glass substrate 2. Considering that surface mounting is performed on the glass surface, the source driver 81 employs a bare chip product. The source driver 81 is supplied with control-related signals such as a power supply, a clock signal, and a line synchronization signal and light amount correction data (for example, 8-bit multi-value data) from the outside of the exposure apparatus 33 via the FPC 80. As will be described in detail later, the source driver 81 is a drive parameter setting unit for the organic electroluminescence element 1. More specifically, the source driver 81 is based on the light amount correction data passed through the FPC 80. This is for setting the drive current value.

  In the glass substrate 2, the joint portion of the FPC 80 and the source driver 81 are connected through, for example, an ITO circuit pattern (not shown) having a metal formed on the surface, and the FPC 80 is connected to the source driver 81 as drive parameter setting means. Control signals such as light quantity correction data, a clock signal, and a line synchronization signal are input via the control signal. Thus, the FPC 80 as the interface means and the source driver 81 as the drive parameter setting means constitute the drive control unit 78.

  Reference numeral 82 denotes a TFT (Thin Film Transistor) circuit formed on the glass substrate 2. The TFT circuit 82 includes a shift controller, a data latch unit, and the like, a gate controller that controls the timing of turning on / off the light emitting elements, and a driving circuit that supplies a driving current to each organic electroluminescence element 1 (hereinafter referred to as a pixel circuit). Including. One pixel circuit is provided for each organic electroluminescence element 1 and is arranged in parallel with the light emitting element row formed by the organic electroluminescence element 1. As will be described later in detail, a drive current value for driving each organic electroluminescence element 1 is set in the pixel circuit by a source driver 81 as drive parameter setting means.

  The TFT circuit 82 is supplied with a control signal such as a power supply, a clock signal, and a line synchronization signal and image data (1-bit binary data) from the outside of the exposure apparatus 33 via the FPC 80. The TFT circuit 82 supplies these power supplies. And the lighting / extinguishing timing of each light emitting element is controlled based on the signal.

  84 is sealing glass. When the organic electroluminescent element 1 is affected by moisture, the light emitting region shrinks with time (shrinking), or the light emitting characteristics are extremely deteriorated due to the occurrence of a non-light emitting portion (dark spot) in the light emitting region. , Sealing to block moisture is necessary. In Example 1, the solid sealing method in which the sealing glass 84 is attached to the glass substrate 2 through an adhesive is employed. However, in order to adsorb moisture in the sealing region, the sealing glass and the glass substrate 2 may be adsorbed. A desiccant (not shown) may be disposed. In general, the sealing region is required from several millimeters to several centimeters in the sub-scanning direction from the light emitting element array formed by the organic electroluminescence element 1, and in the first embodiment, 2000 micrometers is secured as a sealing margin.

  Reference numeral 77 denotes a light quantity sensor unit in which a plurality of light quantity sensors made of amorphous silicon or the like are arranged along the glass substrate 2 in the main scanning direction. The amount of light emitted from each organic electroluminescence element 1 is measured by the light amount sensor unit 77. The output of the light amount sensor unit 77 is once taken into the TFT circuit 82 by wiring (not shown), and after undergoing signal processing such as amplification and analog-digital conversion, the FPC 80, the relay board 72 (see FIG. 2), and the cable 76 (see FIG. 2). To the outside of the exposure device 33.

  This signal is received and processed by a controller 61 (see FIG. 4), which will be described later, to generate light quantity correction data (for example, 8 bits), but the light quantity sensor unit 77 measures each organic electroluminescence element 1. The total amount of emitted light, and not the light emission luminance distribution in the light emitting region. Therefore, although the total light emission amount of the organic electroluminescence element 1 can be recovered by correction based on the light amount correction data, it is difficult to recover the light emission luminance distribution in the light emission region.

  In Example 1, since the light emission luminance in the light emitting region of the organic electroluminescent element 1 is uniform as already described, the deterioration of the organic electroluminescent element 1 occurs uniformly, and even when the deterioration occurs, the light emitting region The distribution of light emission luminance at is not changed.

  For this reason, the exposure apparatus 33 using the organic electroluminescence element 1 of Example 1 measures the light emission quantity of each organic electroluminescence element 1 by the light quantity sensor unit 77 as described above, and based on the measured light emission quantity, for example, Only by increasing the drive current for driving the organic electroluminescent element 1, it is possible to reliably recover both the total light emission amount of the organic electroluminescent element 1 and the distribution of light emission luminance in the light emitting region. Play.

  In the first embodiment, the FPC 80 serving as the interface means constituting the drive control unit 78 and the source driver 81 serving as the drive parameter setting means are provided at a position on the extension line (EL_dir) of the light emitting element row formed by the organic electroluminescence element 1. I made it.

  With such an arrangement, the drive control unit 78 is arranged at a position that does not overlap the light emitting element array at an arbitrary position in the long side direction (main scanning direction) of the glass substrate 2. At the same time, in this configuration, at any position in the long side direction (main scanning direction) of the glass substrate 2, the drive control unit 78 does not overlap with the TFT circuit 82 (including the pixel circuit) formed in parallel with the light emitting element array. Will be placed. With such an arrangement, the size of the glass substrate 2 can be reduced.

  FIG. 4 is a circuit diagram relating to the exposure apparatus 33 according to the first embodiment of the present invention. Hereinafter, the lighting control by the TFT circuit 82 and the source driver 81 will be described in more detail with reference to FIG.

  In FIG. 4, reference numeral 61 denotes a controller incorporated in the image forming apparatus, which receives image data from a computer or the like (not shown) and generates printable image data, and as described above, a light amount sensor incorporated in the exposure apparatus 33. Light amount correction data is generated based on the output of the unit 77 (see FIG. 3).

  An image memory 85 stores binary image data generated by the controller 61 based on a command transferred from a computer (not shown). A light amount correction data memory 86 stores light amount correction data. The light quantity correction data memory 86 is a rewritable nonvolatile memory such as an EEPROM. In the manufacturing process of the exposure apparatus 33, the light emission amount and the light emission luminance distribution of all the organic electroluminescence elements 1 are measured for each exposure apparatus 33, and the light emission of each organic electroluminescence element 1 is based on these measurement results. A step of generating light amount correction data for making the light amount uniform is included, and the light amount correction data memory 86 stores the value of the light amount correction data.

  The controller 61 can update the light amount correction data to the light amount correction data newly generated based on the output of the light amount sensor unit 77 (see FIG. 3).

  A timing generation unit 87 generates a control signal related to the timing for driving the exposure apparatus 33. The image data stored in the image memory 85 and the light amount correction data stored in the light amount correction data memory 86 (or copied in advance to another high-speed memory not shown) are the clock signal and line generated by the timing generation unit 87. Based on a signal such as a synchronization signal, the signal is supplied from the end of the glass substrate 2 through the cable 76, the connector B 73b, the relay substrate 72, the connector A 73a, and the FPC 80.

  Further, the image data and the timing signal supplied to the glass substrate 2 are supplied to the TFT circuit 82 by a wiring formed on the glass substrate 2, for example, a metal layer on ITO, and the light quantity correction data and the timing signal are also supplied. Similarly, it is supplied to the source driver 81.

  The TFT circuit 82 is roughly divided into a pixel circuit 89 and a gate controller 88. One pixel circuit 89 is provided for each organic electroluminescence element 1, and N groups are provided on the glass substrate 2 with the M pixels of the organic electroluminescence element 1 as one group. In the first embodiment, one group is 8 pixels (that is, M = 8), and this group is 640. Therefore, the total number of pixels is 8 × 640 = 5120 pixels. Each pixel circuit 89 supplies a current to the organic electroluminescent element 1 to drive the driver unit 90, and a current value supplied by the driver to control the lighting of the organic electroluminescent element 1 (that is, a driving current value of the organic electroluminescent element 1) ) Is stored in a capacitor included therein, and the organic electroluminescence element 1 can be driven at a constant current according to a drive current value programmed in advance at a predetermined timing.

  The gate controller 88 includes a shift register that sequentially shifts input binary image data, and a latch unit that is provided in parallel with the shift register and collectively holds the input after a predetermined number of pixels are input to the shift register. The control unit controls these operation timings (both not shown). Further, the gate controller 88 outputs the SCAN_A and SCAN_B signals shown in FIG. 4, thereby turning on / off the organic electroluminescence element 1 connected to the pixel circuit 89 and the timing of the current program period for setting the drive current. To control.

  On the other hand, the source driver 81 has a number of D / A converters 92 (640 in the first embodiment) corresponding to the number N of groups of the organic electroluminescence elements 1 (described later). The light emission luminance of each organic electroluminescent element 1 is uniformly controlled by setting the drive current for each organic electroluminescent element 1 on the basis of the light amount correction data (for example, 8 bits) supplied therethrough.

  FIG. 5 is a cross-sectional view of the organic electroluminescence element 1 and the drive circuit according to the exposure apparatus 33 of Embodiment 1 of the present invention. Hereinafter, the configuration of the organic electroluminescence element 1 in Example 1 will be described in detail with reference to FIG.

  In FIG. 5, 2 is the glass substrate already described in detail.

101 is a base coat layer formed on the surface A on the glass substrate 2 (corresponding to the plane A of FIG. 2), formed by stacking for example SiN and SiO _2. A TFT 102 made of polycrystalline silicon (polysilicon) is formed on the base coat layer 101. In the first embodiment, polycrystalline silicon is used as the TFT 102, but amorphous silicon (amorphous silicon) may be used. Amorphous silicon is disadvantageous compared to polycrystalline silicon in terms of design rules and driving frequency, but has a low manufacturing process and cost merit.

Reference numeral 103 denotes a gate insulating layer made of, for example, SiO ₂ , and insulates the TFT 102 and the gate electrode 104 made of a metal such as Mo at a predetermined interval. 105 is an intermediate layer composed by laminating, for example, SiO ₂ and SiN. The intermediate layer 105 covers the gate electrode 104 and supports a source electrode 106 and a drain electrode 107 made of a metal such as Al along the surface. The source electrode 106 and the drain electrode 107 are connected to the TFT 102 through contact holes provided in the intermediate layer 105 and the gate insulating layer 103, and a predetermined potential difference is applied between the source electrode 106 and the drain electrode 107. By applying a predetermined potential to the gate electrode 104, the TFT 102 operates as a switching transistor.

  Reference numeral 108 denotes a protective layer made of SiN or the like, which completely covers the source electrode 106 and forms a contact hole 109 in a part of the drain electrode 107.

Reference numeral 3 denotes an anode formed on the protective layer 108. In Example 1, ITO (indium tin oxide) is used. As the anode 3, in addition to ITO, IZO (zinc-doped indium oxide), ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO), ZnO, SnO ₂ , In ₂ O ₃ or the like can be used. . The anode 3 can be formed by vapor deposition or the like, but is preferably formed by sputtering or CVD (Chemical Vapor Deposition). The anode 3 is connected to the drain electrode 107 through a contact hole 109.

  As described above, the pixel regulating layer 8 is formed on the surface of the anode 3, and the light emitting layer 6 is formed in contact with the whole of the anode 3 and the pixel regulating layer 8 by a coating process such as a spin coating method. Further, a cathode 7 is formed by vapor deposition in contact with the light emitting layer 6.

  The organic electroluminescence element 1 is formed on the glass substrate 2 by the structure and process described above. The TFTs 102 are formed in a 1: 1 relationship with respect to the individual organic electroluminescence elements 1 and electrically constitute a so-called active matrix circuit. The source electrode 106 is used as a positive electrode, a predetermined potential difference is provided between the source electrode 106 and the cathode 7, and the gate electrode 104 is controlled to a predetermined potential, so that holes are generated in the source electrode 106, the TFT 102, the drain electrode 107, and the anode 3. Then, electrons are injected into the light emitting layer 6, while electrons are injected from the cathode 7 into the light emitting layer 6. In the light emitting layer 6, recombination of holes and electrons occurs, and a light emission phenomenon occurs when excitons generated thereby shift from the excited state to the ground state.

  The light emitted from the light emitting layer 6 passes through the anode 3, the intermediate layer 105, the gate insulating layer 103, the base coat layer 101, and the glass substrate 2, and is emitted from the surface opposite to the surface A to expose a photoreceptor (not shown). Thus, the light emitting layer 6 can be easily sealed by adopting a configuration (bottom emission) in which light is extracted from the surface of the substrate opposite to the surface A on which the light emitting layer 6 is formed. Reference numeral 99 denotes a wiring pattern. For example, an analog signal of the light amount correction data output from the source driver 81 shown in FIG. 4 is connected to the pixel circuit 89 using the wiring pattern 99 provided on the intermediate layer 105. ing.

  As described above in detail, since the organic electroluminescent element 1 of Example 1 has uniform light emission luminance in the light emitting region LA, an exposure apparatus using this as a light source can obtain an electrostatic latent image of a desired shape. Can do.

  Moreover, since the organic electroluminescent element 1 of Example 1 has the uniform thickness of the light emitting layer 6, the electric current distribution which flows through the organic electroluminescent element 1 becomes uniform. Accordingly, since the deterioration of the light emitting area LA of the organic electroluminescent element 1 becomes uniform, the exposure apparatus using the organic electroluminescent element 1 has a substantially long product life and forms a stable latent image over a long period of time. It becomes possible.

  Furthermore, since the light emitting area LA emits light uniformly in the organic electroluminescent element 1 of Example 1, it is not necessary to emit light unnecessarily brightly to obtain a desired light emission luminance, and the power consumption of the exposure apparatus 33 can be reduced. .

  In the exposure apparatus 33, the structures of the organic electroluminescence elements 1 may all be the same or different from each other.

  FIG. 6 is a block diagram of an image forming apparatus equipped with an exposure device 33 to which the organic electroluminescence element 1 of Example 1 of the present invention is applied.

  In FIG. 6, the image forming apparatus 21 arranges development stations for four colors, a yellow developing station 22Y, a magenta developing station 22M, a cyan developing station 22C, and a black developing station 22K, in a vertical stepwise manner. Is provided with a paper feed tray 24 in which the recording paper 23 is accommodated, and a recording paper transport path serving as a transport path for the recording paper 23 supplied from the paper feed tray 24 at locations corresponding to the developing stations 22Y to 22K. 25 is arranged vertically from above to below.

  The developing stations 22Y to 22K form yellow, magenta, cyan, and black toner images in order from the upstream side of the recording paper conveyance path 25. The yellow developing station 22Y includes a photoconductor 28Y and a magenta developing station 22M. The photosensitive member 28M and the cyan developing station 22C include the photosensitive member 28C, the black developing station 22K includes the photosensitive member 28K, and each developing station 22Y to 22K includes a series of electrophotographic systems such as a developing sleeve and a charger (not shown). The member which implement | achieves the image development process in is included.

  Further, exposure devices 33Y, 33M, 33C, and 33K for exposing the surfaces of the photoreceptors 28Y to 28K to form electrostatic latent images are disposed below the developing stations 22Y to 22K.

  The developing stations 22Y to 22K are different in the color of the filled developer, but the configuration is the same regardless of the developing color. Therefore, the developing stations are excluded unless particularly necessary to simplify the following description. 22, the photosensitive member 28, and the exposure device 33 will be described without specifying specific colors.

  FIG. 7 is a configuration diagram illustrating the periphery of the developing station 22 in the image forming apparatus 21 according to the first exemplary embodiment of the present invention. In FIG. 7, the developing station 22 is filled with a developer 26 that is a mixture of carrier and toner. Reference numerals 27a and 27b denote stirring paddles for stirring the developer 26. The toner in the developer 26 is charged to a predetermined potential by friction with the carrier by the rotation of the stirring paddles 27a and 27b, and the interior of the developing station 22 is also charged. By circulating, the toner and the carrier are sufficiently stirred and mixed. The photoreceptor 28 is rotated in the direction D3 by a driving source (not shown). A charger 29 charges the surface of the photoreceptor 28 to a predetermined potential. 30 is a developing sleeve, and 31 is a thinning blade. The developing sleeve 30 has a mag roll 32 having a plurality of magnetic poles formed therein. The layer thickness of the developer 26 supplied to the surface of the developing sleeve 30 is regulated by the thinning blade 31 and the developing sleeve 30 is rotated in a direction D4 by a driving source (not shown). The developer 26 is supplied to the surface of the developing sleeve 30 by the action, and an electrostatic latent image formed on the photoconductor 28 is developed by an exposure device to be described later, and the developer 26 that has not been transferred to the photoconductor 28 is developed in the developing station. 22 is collected inside.

  Reference numeral 33 denotes the exposure apparatus already described. The image forming apparatus 21 to which the exposure apparatus 33 according to the first embodiment is applied has a long product life because the exposure apparatus 33 can stably form a latent image over a long period of time as described above, and the exposure apparatus according to the first embodiment. Since the electrostatic latent image 33 having a desired shape can be obtained over a long period of time, a high-quality image can always be formed.

  The exposure apparatus 33 according to the first embodiment is a linear arrangement of organic electroluminescence elements with a resolution of 600 dpi (dot / inch). The exposure apparatus 33 converts image data to a photoconductor 28 charged to a predetermined potential by a charger 29. In response to this, the organic electroluminescence element is selectively turned ON / OFF to form an electrostatic latent image having a maximum A4 size. Only the toner of the developer 26 supplied to the surface of the developing sleeve 30 adheres to the electrostatic latent image portion, and the electrostatic latent image is visualized.

  A transfer roller 36 is provided at a position facing the recording paper conveyance path 25 with respect to the photoreceptor 28, and is rotated in the direction D5 by a driving source (not shown). A predetermined transfer bias is applied to the transfer roller 36, and the toner image formed on the photoconductor 28 is transferred to the recording paper conveyed through the recording paper conveyance path 25.

  Hereinafter, the description will be continued returning to FIG.

  As described above, the image forming apparatus 21 according to the first exemplary embodiment is a tandem type color image forming apparatus in which a plurality of developing stations 22Y to 22K are arranged in a stepwise manner in the vertical direction, and is equivalent to a color inkjet printer. It aims at size. Since a plurality of units are arranged in the developing stations 22Y to 22K, in order to reduce the size of the image forming apparatus 21, the developing stations 22Y to 22K themselves are reduced in size and are arranged around the developing stations 22Y to 22K. It is necessary to reduce the members involved in the image process and to reduce the arrangement pitch of the developing stations 22Y to 22K as much as possible.

  In consideration of user convenience when installing the image forming apparatus 21 on the desktop in an office or the like, in particular, accessibility to the recording paper 23 at the time of paper feeding or paper ejection, from the bottom surface of the image forming apparatus 21 to the paper feed port 65. The height is preferably 250 mm or less. In order to realize this, it is necessary to suppress the height of the entire developing stations 22Y to 22K to about 100 mm in the entire configuration of the image forming apparatus 21.

  However, the existing LED head, for example, has a thickness of about 15 mm, and if it is disposed between the developing stations 22Y to 22K, it is difficult to achieve the target. According to the examination results of the present inventors, when the thickness of the exposure device 33 is 7 mm or less, the height of the entire development station is 100 mm or less even if the exposure devices 33Y to 33K are arranged in the gaps between the development stations 22Y to 22K. It is possible to suppress.

  A toner bottle 37 stores yellow, magenta, cyan, and black toners. A toner transport pipe (not shown) is provided from the toner bottle 37 to each of the developing stations 22Y to 22K, and supplies toner to each of the developing stations 22Y to 22K.

  A paper feed roller 38 is rotated in the direction D1 by controlling an electromagnetic clutch (not shown), and feeds the recording paper 23 loaded in the paper feeding tray 24 to the recording paper transport path 25.

  A registration paper 39 and a pair of pinch rollers 40 are provided as a nip conveyance means on the inlet side in the recording paper conveyance path 25 positioned between the paper supply roller 38 and the transfer portion of the most upstream yellow developing station 22Y. The registration roller 39 and the pinch roller 40 pair temporarily stop the recording paper 23 conveyed by the paper supply roller 38 and convey it in the direction of the yellow developing station 22Y at a predetermined timing. This temporary stop restricts the leading edge of the recording paper 23 in parallel with the axial direction of the registration roller 39 and pinch roller 40 pair, thereby preventing the recording paper 23 from skewing.

  Reference numeral 41 denotes a recording paper passage detection sensor. The recording paper passage detection sensor 41 is constituted by a reflective sensor (photo reflector), and detects the leading edge and the trailing edge of the recording paper 23 based on the presence or absence of reflected light.

  When the rotation of the registration roller 39 is started (the power transmission is controlled by an electromagnetic clutch (not shown) and the rotation is turned ON / OFF), the recording paper 23 is conveyed along the recording paper conveyance path 25 in the direction of the yellow developing station 22Y. However, starting from the rotation start timing of the registration roller 39, the writing timing of the electrostatic latent images by the exposure devices 33Y to 33K disposed in the vicinity of the developing stations 22Y to 22K is independently controlled.

  A fixing device 43 is provided as a nip conveying means on the outlet side in the recording paper conveyance path 25 located further downstream of the most downstream black developing station 22K. The fixing device 43 includes a heating roller 44 and a pressure roller 45. The heating roller 44 is a multi-layered roller composed of a heating belt, a rubber roller, and a core material (both not shown) in order from the surface. Among them, the heat generating belt is a belt having a three-layer structure, and is composed of a release layer, a silicon rubber layer, and a base material layer (both not shown) from the side closer to the surface. The release layer is made of a fluororesin having a thickness of about 20 to 30 micrometers and imparts release properties to the heating roller 44. The silicon rubber layer is made of silicon rubber having a thickness of about 170 micrometers and gives the pressure roller 45 appropriate elasticity. The base material layer is made of a magnetic material that is an alloy of iron, nickel, chromium, or the like.

  A back core 26 includes an exciting coil. Inside the back core 46, an excitation coil in which a predetermined number of copper wires (not shown) whose surfaces are insulated is bundled in the direction of the rotation axis of the heating roller 44, and at both ends of the heating roller 44, the heating roller It circulates along the circumferential direction of 44. When an alternating current of about 30 kHz is applied to the exciting coil from an exciting circuit (not shown) that is a semi-resonant inverter, a magnetic flux is generated in a magnetic path constituted by the back core 46 and the base layer of the heating roller 44. Due to this magnetic flux, an eddy current is formed in the base material layer of the heat generating belt of the heating roller 44 and the base material layer generates heat. The heat generated in the base material layer is transmitted to the release layer through the silicon rubber layer, and the surface of the heating roller 44 generates heat.

  Reference numeral 47 denotes a temperature sensor for detecting the temperature of the heating roller 44. The temperature sensor 47 is a ceramic semiconductor obtained by sintering at a high temperature using a metal oxide as a main raw material, and it is possible to measure the temperature of a contacted object by applying a change in load resistance according to the temperature. it can. The output of the temperature sensor 47 is input to a control device (not shown). The control device controls the power output to the exciting coil inside the back core 46 based on the output of the temperature sensor 47, and the surface temperature of the heating roller 44 is about 170 °. Control to be C.

  When the recording paper 23 on which the toner image is formed is passed through the nip formed by the heating roller 44 and the pressure roller 45 that are controlled in temperature, the toner image on the recording paper 23 is connected to the heating roller 44. The toner image is fixed on the recording paper 23 by being heated and pressurized by the pressure roller 45.

  A recording paper trailing edge detection sensor 48 monitors the discharge state of the recording paper 23. Reference numeral 52 denotes a toner image detection sensor. The toner image detection sensor 52 is a reflective sensor unit that uses a plurality of light emitting elements (both visible light) having different emission spectra and a single light receiving element, and changes the image color between the background of the recording paper 23 and the image forming portion. Accordingly, the image density is detected by utilizing the fact that the absorption spectrum is different. Further, since the toner image detection sensor 52 can detect not only the image density but also the image forming position, the image forming apparatus 21 according to the first exemplary embodiment is provided with two toner image detection sensors 52 in the width direction of the image forming apparatus 21, and recording paper. The image formation timing is controlled based on the detection position of the image position deviation amount detection pattern formed on the image 23.

  53 is a recording paper transport drum. The recording paper transport drum 53 is a metal roller whose surface is covered with rubber having a thickness of about 200 micrometers, and the recording paper 23 after fixing is transported along the recording paper transport drum 53 in the direction D2. At this time, the recording sheet 23 is cooled by the recording sheet conveying drum 53 and is bent and conveyed in the direction opposite to the image forming surface. As a result, curling that occurs when a high density image is formed on the entire surface of the recording paper can be greatly reduced. Thereafter, the recording paper 23 is conveyed in the direction D6 by the kicking roller 55 and discharged to the paper discharge tray 59.

  Reference numeral 54 denotes a face-down paper discharge unit. The face-down paper discharge unit 54 is configured to be rotatable about the support member 56. When the face-down paper discharge unit 54 is opened, the recording paper 23 is discharged in the direction D7. In the closed state, the face-down paper discharge unit 54 is formed with ribs 57 along the transport path on the back surface so as to guide the transport of the recording paper 23 together with the recording paper transport drum 53.

  Reference numeral 58 denotes a drive source. In the first embodiment, a stepping motor is employed. By the drive source 58, peripheral portions of the developing stations 22Y to 22K including the paper feed roller 38, the registration roller 39, the pinch roller 40, the photoconductors (28Y to 28K), and the transfer rollers (36Y to 36K), the fixing device 43, The recording paper transport drum 53 and the kicking roller 55 are driven.

  A controller 61 receives image data from a computer (not shown) via an external network and develops and generates printable image data.

  Reference numeral 62 denotes an engine control unit. The engine control unit 62 controls the hardware and mechanism of the image forming apparatus 21, forms a color image on the recording paper 23 based on the image data transferred from the controller 61, and performs overall control of the image forming apparatus 21. Yes.

  63 is a power supply unit. The power supply unit 63 supplies power of a predetermined voltage to the exposure apparatuses 33Y to 33K, the drive source 58, the controller 61, and the engine control unit 62, and supplies power to the heating roller 44 of the fixing device 43. The power supply unit also includes a so-called high-voltage power supply system such as charging of the surface of the photosensitive member 28, a developing bias applied to the developing sleeve (see reference numeral 30 in FIG. 7), a transfer bias applied to the transfer roller 36, and the like. .

  The power supply unit 63 includes a power supply monitoring unit 64 so that at least the power supply voltage supplied to the engine control unit 62 can be monitored. This monitor signal is detected by the engine control unit 62 to detect a decrease in power supply voltage that occurs when the power switch is turned off or a power failure occurs.

  In the above description, the case where the present invention is applied to a color image forming apparatus has been described. However, the present invention can also be applied to a single color image forming apparatus such as black. When applied to a color image forming apparatus, the development colors are not limited to four colors of yellow, magenta, cyan and black.

(Example 2)
FIG. 8 is an explanatory view showing the structure of the organic electroluminescence element 1 in Example 2 of the present invention. Hereinafter, the structure of the organic electroluminescence element 1 in the embodiment 2 will be described in detail with reference to FIG. 8. The exposure apparatus using the organic electroluminescence element 1 and the image forming apparatus equipped with the exposure apparatus are configured and operated. Since there is no difference in description, explanation is omitted.

  In Example 2, at least the end portion P0 of the pixel regulating layer 8 has high wettability with respect to a solvent such as toluene or xylene that dissolves the organic light emitting material described in detail in Example 1 or a solution in which the organic light emitting material is dissolved. The main chain is a vinyl group, water-absorbing silicon, isocyanate, polyester polymer, polyamide, fluorine-containing polymer, epoxy group, polymer material having a vinyl group, glycidyl group, aryl group, etc. at the end, polyimide, etc. The surface of the water-repellent material is made of a material having a surface that has improved wettability to the solvent or solution by ultraviolet irradiation treatment or plasma treatment. Further, it is desirable that the surface roughness Ra of the end portion P0 of the pixel restricting layer 8 is roughened to about 5 nanometers by not only selecting the material surface but also subjecting the end portion P0 of the pixel restricting layer 8 to plasma processing and etching. Thus, by selecting the material of the pixel restricting layer 8 and performing the surface treatment, the wettability with respect to the light emitting layer 6 at the end P0 of the pixel restricting layer 8 can be improved. In Example 2, the contact angle with the solvent or solution at the end portion P0 of the pixel regulating layer 8 is set to 45 degrees or less as the degree of wettability by selecting the material of the pixel regulating layer 8 and the surface treatment described above.

  Further, as the material constituting the pixel regulation layer 8, a material made of silicon nitride or aluminum nitride may be selected. These materials are superior in terms of insulating properties, pixel regulation accuracy, and the like, and have the advantage of being adopted. In this case, a sufficient cleaning process, ultraviolet irradiation process, heat treatment, plasma process, etc. are performed after forming the pixel regulating layer 8 so that the contact angle of the pixel regulating layer 8 with the solvent or solution at P0 is 45 degrees or less. can do. As a material constituting the pixel regulation layer 8, silicon oxide or aluminum oxide can be used.

  Further, in Example 2, as shown in FIG. 8, an angle θ1 formed by the surface of the anode 3 constituting the organic electroluminescence element 1 and the pixel regulating layer 8 in contact with the surface is set in the light emitting region LA of the organic electroluminescence element 1. The light emission luminance is configured to be substantially uniform, and the angle θ1 is preferably 3 degrees or more and 45 degrees or less, and more preferably 3 degrees or more and 10 degrees or less as described later.

  In order to form the end portion P0 of the pixel regulating layer 8 in the pixel regulating layer 8 in a tapered shape, an etching method in which the etching gas or the kind of the etching liquid, the etching time, and the etching mask are appropriately selected is applied in the case of forming by etching. By doing so, the taper shape and its angle θ1 can be easily adjusted. In the case of forming by development using a photosensitive material, the taper shape and the angle θ1 can be easily adjusted by appropriately selecting an exposure time, an exposure mask, a development time, and the like.

  In particular, the etching region is gradually enlarged using a plurality of masks, and the thickness removed by the etching is controlled by adjusting the etching time, whereby the surface of the anode 3 at the end P0 of the pixel regulating layer 8 and The angle θ1 formed with the pixel regulating layer 8 in contact with the pixel regulating layer 8 can be adjusted with high accuracy.

  On the other hand, if the angle θ1 formed with the pixel regulation layer 8 in contact with the surface of the anode 3 is set to be smaller than 3 degrees, the film strength at the end P0 of the pixel regulation layer 8 is insufficient, and the light emission area LA originally required for the pixel regulation layer 8 The function of restricting the light emission is impaired, and the shape of the light emitting area LA is not constant.

  According to the knowledge of the inventors, as described above, the contact angle with the solvent or solution at the end portion P0 of the pixel regulation layer 8 is set to 45 degrees or less, and the surface of the anode 3 and the pixel regulation layer 8 in contact with the surface When the angle θ1 is changed to 45 °, the variation in the thickness of the light emitting layer 6 in the light emitting region LA is about 30%. Further, the surface of the anode 3 and the pixel restricting layer 8 in contact therewith When the angle θ1 formed by is configured to be 10 degrees, it can be suppressed to 20% or less. Thus, reducing the variation in the thickness of the light emitting layer 6 directly leads to the uniform emission luminance in the light emitting region LA, and the light emission luminance distribution in the light emitting region LA can be made closer to a rectangle.

  The degree of wettability is such that the contact angle with the solvent or solution at the end P0 of the pixel regulating layer 8 is 45 degrees or less, and the wettability with respect to the light emitting layer 6 at the end P0 of the pixel regulating layer 8 is improved. The variation in the thickness of the layer 6 is reduced because the influence of capillary action and surface tension at the end portion P0 of the pixel restricting portion 8 can be eliminated as much as possible.

  Furthermore, the variation in the thickness of the light emitting layer 6 is reduced by controlling the angle θ1 formed between the surface of the anode 3 and the pixel restricting layer 8 in contact therewith to a desired value. This is because the change in the angle with the anode 3 at the tapered portion is sufficiently small, thereby eliminating the step at the boundary between the anode 3 and the pixel restricting layer 8, that is, the discontinuous state between the anode 3 and the pixel restricting layer 8. is there.

  In the conventional organic electroluminescence element 1, even if a step exists at the boundary between the anode 3 and the pixel regulation layer 8, or even if a taper is formed, the step is substantially ignored without managing the angle θ1. Thus, the organic electroluminescence element 1 is formed by the process of the coating process, and the thickness of the light emitting layer 6 in the light emitting region LA varies due to the capillary phenomenon and the surface tension resulting from this structure. However, as described above, the material surface and the surface state of the pixel restriction layer 8 are improved, and the shape of the end of the pixel restriction layer 8 on the side that restricts the light emitting area LA is tapered, and is 3 degrees or more and 45 degrees or less. Preferably, by forming at 3 degrees or more and 10 degrees or less, the influence of capillary action and surface tension resulting from the structure of the tapered portion is greatly relieved.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In the above embodiment, the case where the pixel restricting layer 8 is provided to the anode 3 formed on the glass substrate 2 in the organic electroluminescence element 1 to restrict the light emitting region LA has been described. Needless to say, the technical idea of the second embodiment can be similarly applied to a structure in which the pixel regulating layer 8 is provided on the formed cathode 7 to regulate the light emitting area LA.

(Example 3)
FIG. 9 is an explanatory view showing the structure of the organic electroluminescence element 1 in Example 3 of the present invention. Hereinafter, the structure of the organic electroluminescence element 1 in Example 3 will be described in detail with reference to FIG. 9. The exposure apparatus using the organic electroluminescence element 1 and the image forming apparatus equipped with the exposure apparatus are configured and operated. Since there is no difference between them, the description is omitted.

  In Example 3, as shown in FIG. 9, the surface of the anode 3 constituting the organic electroluminescence element 1 and the pixel regulation layer 8 in contact with the surface are arranged on the side regulating the light emitting area LA in the pixel regulation layer 8 (that is, pixel regulation). The end portion P0) of the layer 8 is composed of a curved surface whose thickness decreases toward the end portion. Further, as shown in the figure, the end portion P0 of the pixel restricting layer 8 is constituted by a curved surface convex downward with respect to the surface of the anode 3 in contact with the pixel restricting layer 8 as shown in the figure.

  In order to form the end portion P0 of the pixel regulating layer 8 as a free-form surface in the pixel regulating layer 8, an etching method in which an etching gas or etchant type, etching time, and etching mask are appropriately selected is applied when forming by etching. By doing so, the slope of the curved surface can be easily changed. In the case of forming by development using a photosensitive material, the slope of the curved surface can be easily changed by appropriately selecting the exposure time, the exposure mask, the development time, and the like. In particular, the pitch at the time of gradually expanding the etching region using a plurality of masks is changed, and the thickness removed by the etching is adjusted by adjusting the etching time, whereby the anode at the end P0 of the pixel regulation layer 8 is controlled. 3 and the shape of the pixel regulating layer 8 in contact therewith can be adjusted with high accuracy.

  On the other hand, if the thickness of the pixel restricting layer 8 in contact with the surface of the anode 3 is made thinner than 0.05 micrometers, the film strength at the end portion P0 of the pixel restricting layer 8 is insufficient, and the pixel restricting layer 8 is originally required. The function of regulating the light emitting area LA is impaired, and there is a problem that the shape of the light emitting area LA is not constant. Accordingly, in Example 3, the thickness of the outermost end portion of the end portion P0 of the pixel regulating layer 8 is set to 0.05 micrometers.

  Further, in Example 3, at least the end portion P0 of the pixel regulating layer 8 has high wettability with respect to a solvent such as toluene or xylene that dissolves the organic light emitting material described in detail in Example 1 or a solution in which the organic light emitting material is dissolved. The main chain is a vinyl group, water-absorbing silicon, isocyanate, polyester polymer, polyamide, fluorine-containing polymer, epoxy group, polymer material having a vinyl group, glycidyl group, aryl group, etc. at the end, polyimide, etc. The surface of the water-repellent material is subjected to ultraviolet irradiation treatment or plasma treatment to increase the wettability to the solvent or solution. In addition to simply selecting the material surface, it is desirable to roughen the surface roughness Ra of the end portion P0 of the pixel regulating layer 8 to about 5 nanometers by performing plasma processing and etching processing on the end portion P0 of the pixel regulating layer 8. . By thus selecting the material of the pixel regulating layer 8 and performing the surface treatment, the wettability of the light emitting layer 6 can be improved at the end P0 of the pixel regulating layer 8. In Example 2, the contact angle with the solvent or solution at the end portion P0 of the pixel regulating layer 8 is set to 45 degrees or less as the degree of wettability by selecting the material of the pixel regulating layer 8 and the surface treatment described above.

  According to the knowledge of the inventors, as described above, the contact angle with the solvent or solution at the end portion P0 of the pixel regulating layer 8 is set to 45 degrees or less, and the end portion P0 of the pixel regulating layer 8 is set to the pixel regulating layer 8. A plurality of organic electroluminescent elements by forming a curved surface convex downward with respect to the surface of the anode 3 in contact with the anode 3 and further setting the thickness of the outermost portion at the end portion P0 of the pixel regulating layer 8 to 0.05 micrometers. 1, the shape of the light emitting region LA was extremely stable, and the variation in the thickness of the light emitting layer 6 in the light emitting region LA could be suppressed to 20% or less. Thus, reducing the variation in the thickness of the light emitting layer 6 directly leads to the uniform emission luminance in the light emitting region LA, and the light emission luminance distribution in the light emitting region LA can be made closer to a rectangle.

  The degree of wettability is such that the contact angle with the solvent or solution at the end P0 of the pixel regulating layer 8 is 45 degrees or less, and the wettability with respect to the light emitting layer 6 at the end P0 of the pixel regulating layer 8 is improved. The variation in the thickness of the layer 6 is reduced because the influence of capillary action and surface tension at the end portion P0 of the pixel restricting portion 8 can be eliminated as much as possible.

  Further, the end portion P0 of the pixel restricting layer 8 is configured by a curved surface whose thickness decreases toward the end portion, and the end portion P0 of the pixel restricting layer 8 further protrudes downward with respect to the surface of the anode 3 in contact with the pixel restricting layer 8. The variation in the thickness of the light-emitting layer 6 is reduced when the pixel restricting layer 8 emits light when the end portion P0 of the pixel restricting layer 8 has a thickness of 0.05 micrometers. The change in angle with the anode 3 at the tapered portion that regulates the area LA is sufficiently small, thereby eliminating the step at the boundary between the anode 3 and the pixel regulating layer 8, that is, the discontinuous state between the anode 3 and the pixel regulating layer 8. It is to be done.

  In the conventional organic electroluminescence device 1, although there is a step at the boundary between the anode 3 and the pixel regulating layer 8, the organic electroluminescence device 1 is formed by the process of the coating process ignoring this step. In addition, the thickness of the light emitting layer 6 in the light emitting region LA varies due to capillary action and surface tension resulting from this structure. However, as described above, the material surface and the surface state of the pixel restricting layer 8 are improved, and the end portion P0 of the pixel restricting layer 8 is formed with a curved surface that protrudes downward with respect to the surface of the anode 3 in contact with the pixel restricting layer 8. In addition, by setting the thickness of the outermost end portion at the end portion P0 of the pixel regulating layer 8 to 0.05 micrometers, the influence of capillary action and surface tension due to the structure of the tapered portion is greatly reduced.

  The structure of the third embodiment can sufficiently reduce the angle formed with the anode 3 at the end P0 of the pixel restricting layer 8 while ensuring the thickness of the pixel restricting layer 8. Thereby, the organic electroluminescence element 1 in which the thickness of the light emitting layer 6 in the light emitting region LA is uniform can be easily realized while maintaining high insulation, and the light emission luminance distribution of the light emitted from the light emitting region LA is made uniform. be able to.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In the above embodiment, the case where the pixel restricting layer 8 is provided to the anode 3 formed on the glass substrate 2 in the organic electroluminescence element 1 to restrict the light emitting region LA has been described. Needless to say, the technical idea of the third embodiment can be similarly applied to a structure in which the pixel regulating layer 8 is provided on the formed cathode 7 to regulate the light emitting area LA.

Example 4
FIG. 10 is an explanatory view showing the structure of the organic electroluminescence element 1 in Example 4 of the present invention. Hereinafter, the structure of the organic electroluminescent element 1 in Example 4 will be described in detail with reference to FIG. 10. The exposure apparatus using the organic electroluminescent element 1 and the image forming apparatus equipped with the exposure apparatus are configured and operated. Since there is no difference between them, the description is omitted.

  The organic electroluminescence device 1 in Example 4 has an anode 3 for injecting holes, a light emitting layer 6, a cathode 7 for injecting electrons, and a part of the anode 3 so as to control the injection of holes to control the light emitting layer. 6 has a plurality of layers (pixel restricting layer 8a and pixel restricting layer 8b) for restricting the light emitting area LA, and the pixel restricting layer is configured to make the light emission luminance in the light emitting area LA substantially uniform. is there. As shown in detail in FIG. 10, reference numeral 8 a denotes a first pixel regulation layer, which mainly has a function of ensuring overall insulation between the anode 3 and the cathode 7. Reference numeral 8b denotes a second pixel regulation layer, which mainly has a function for regulating the light emitting area LA. In this case, a material that covers the anode 3 and the cathode 7 with good insulation is used for the first pixel regulation layer 8a, and a material that can obtain accuracy such as thinness and fineness is used for the second pixel regulation layer 8b. It is desirable. By using different materials for the first pixel restriction layer 8a and the second pixel restriction layer 8b as described above, it is possible to further enhance the function separation effect.

  A further structural feature of the organic electroluminescent element 1 of Example 4 is that the pixel restricting layer is in contact with the second pixel restricting layer 8b formed in contact with the anode, and in contact with the second pixel restricting layer 8b. That is, the first pixel restriction layer 8a is formed and covers a part of the second pixel restriction layer 8b.

  Hereinafter, the structure of the organic electroluminescence element 1 in Example 4 will be described in detail with reference to FIG. In the following description, for the sake of simplicity, the first pixel regulating layer 8a is in contact with the pixel regulating layer 8b and the end on the light emitting area LA side is referred to as “end P1 of the first pixel regulating layer 8a”. (See P1 in the figure).

  First, the structure of the end portion P1 of the first pixel regulating layer 8a will be described.

  An angle θ2 formed by the first pixel regulating layer 8a in contact with the surface of the second pixel regulating device 8b formed in contact with the anode 3 at the end portion P1 of the pixel regulating layer 8a is set to 3 degrees or more and 45 degrees or less. It is more preferable that it is 3 degrees or more and 10 degrees or less. In Example 4, the first pixel restricting layer 8a does not directly restrict the light emitting area LA, but the first pixel restricting layer 8a is formed around the second pixel restricting layer 8b. The effect of forming the light emitting layer 6 is not zero, and it is desirable to apply the conditions shown in the second embodiment to the first pixel regulating layer 8a.

  Also in the fourth embodiment, at least the end portion P1 of the first pixel regulating layer 8a is applied to a solvent such as toluene or xylene that dissolves the organic light emitting material described in detail in the first embodiment, or a solution in which the organic light emitting material is dissolved. Polymer materials with vinyl groups, water-absorbing silicon, isocyanates, polyester polymers, polyamides, fluorine-containing polymers, epoxy groups, or vinyl groups, glycidyl groups, aryl groups, etc. as the main chain Alternatively, it is desirable that the surface of a water-repellent material such as polyimide has a surface with high wettability to the solvent or solution by ultraviolet irradiation treatment or plasma treatment. Further, it is desirable that the surface roughness Ra of the end portion P1 of the first pixel regulating layer 8a is roughened to about 5 nanometers by performing plasma processing and etching processing on the end portion P1 of the first pixel regulating layer 8a. Thus, by selecting the material of the first pixel regulating layer 8a and performing the surface treatment, the wettability with respect to the light emitting layer 6 at the end portion P1 of the first pixel regulating layer 8a can be improved. In Example 4, the contact angle with the solvent or solution at the end P1 of the pixel regulating layer 8 is set to 45 degrees or less as the degree of wettability by selecting the material of the pixel regulating layer 8 and the surface treatment described above.

  In order to form the end portion P1 of the first pixel regulating layer 8a in a tapered shape, an etching method in which the type of etching gas or etching liquid, the etching time, and the etching mask are appropriately selected is applied when forming by etching. The taper shape can be easily adjusted. In the case of forming by development using a photosensitive material, the taper shape can be easily adjusted by appropriately selecting the exposure time, exposure mask, development time and the like. In particular, the angle θ2 can be accurately adjusted by gradually expanding the etching region using a plurality of masks and adjusting the etching time to control the thickness removed by etching. In the fourth embodiment, the end portion P1 of the first pixel regulating layer 8a may be formed of a curved surface as in the third embodiment.

  As described in the first embodiment, the material constituting the pixel regulation layer is advantageously an opaque material. In Example 4, since the first pixel regulating layer 8a and the second pixel regulating layer 8b are functionally separated, the thickness of the first pixel regulating layer 8a is set to a relatively large value of about 5 micrometers, and By configuring the first pixel regulation layer 8a with an organic substance such as polyimide whose carbon particle dispersion amount is controlled to be relatively low, both insulation and low light transmittance required for the first pixel regulation layer 8a can be achieved. Is possible.

  Next, the second pixel regulating layer 8b will be described in detail.

  The second pixel regulating layer 8b mainly has a function of regulating the light emitting area LA, and it is necessary to ensure wettability with respect to the light emitting layer 6 as already described in other embodiments. In order to satisfy this requirement, it is desirable that the second pixel regulation layer 8b is made of, for example, SiN or AlN. These materials are superior in terms of insulation, pixel regulation accuracy, etc., and are excellent in wettability with the above-mentioned solvent or solution as the material itself. In order to ensure wettability, the contact angle with the solvent or solution can be reduced to 45 degrees or less by performing sufficient cleaning treatment, ultraviolet irradiation treatment, heat treatment, plasma treatment, etc. after the pixel regulation layer 8 is formed. Sufficient wettability with respect to the light emitting layer 6 can be ensured.

  As already described in the first embodiment, the step between the anode 3 and the second pixel regulation layer 8b is preferably 0.05 micrometers or more and 2 micrometers or less, and the thickness of the second pixel regulation layer 8b is 0.05 micrometers. It is more desirable to set it to not less than meter and not more than 0.5 micrometer. On the other hand, it is desirable that the thickness of the first pixel regulating layer 8b is, for example, about 5 micrometers to ensure insulation. That is, the thickness of the first pixel restricting layer 8a and the thickness of the second pixel restricting layer 8b are configured to satisfy the relationship of “the thickness 8a of the first pixel restricting layer> the thickness 8b of the second pixel restricting layer”. It is desirable to do. In this case, the first pixel restricting layer 8a is a factor that governs the thickness of the entire pixel restricting layer, but the relationship between the pixel size in the exposure device 33 (see FIG. 3) and the thickness of the first pixel restricting layer 8a is From the same viewpoint as already described in the first embodiment, the thickness of the first pixel regulating layer 8a is configured to be equal to or less than the width of the light emitting area LA and 1.5% or more of the width of the light emitting area LA. It is desirable.

  The second pixel restricting layer 8b may be made of metal. When the second pixel regulating layer 8b is made of metal, the light transmittance can be substantially zero as already described in the first embodiment. In the fourth embodiment, the first pixel regulation layer 8a is made of an insulating material so as to provide insulation between the anode 3 and the cathode 7. Therefore, the second pixel regulation layer 8b is required in the first embodiment. It is not necessary to satisfy the condition “a metal in which holes are not easily injected into the light emitting layer 6”. Therefore, in Example 4, any metal material can be used as long as the patterning property is satisfied.

  However, in FIG. 10, the second pixel regulation layer 8 b is provided independently in each organic electroluminescence element 1, but the second pixel regulation layer 8 b straddles a plurality of organic electroluminescence elements 1 (that is, In the case of being formed in a solid state and having an opening at a predetermined position of the anode 3), a metal material having a low resistance value is adopted because a drive current leaks to an adjacent pixel. Can not. In this case, it is desirable to use a conductive material having a predetermined resistance value such as a metal oxide or nitride for the second pixel regulation layer 8b. Specifically, MoO3 can be used for a metal oxide, and SiN can be used for a nitride. Further, in this case, the leakage current can be prevented if the conductivity in the plane direction is 1 megaohm or more. In order to further improve the effect of suppressing the leakage current, it is desirable that the conductivity in the surface direction be further 10 megaohms or more.

  Now, as a process for obtaining the structure shown in FIG. 10, (I) for example, SiN, which becomes the second restriction layer 8b in a later step, in both the light emitting region LA and the second pixel restriction layer 8b in the figure. A material such as Cr is vapor-deposited on one side, (II) a photosensitive resin to be the first pixel regulating layer 8a is applied on the other side, and (III) a photomask having the shape of the first pixel regulating layer 8a is used. The first pixel restricting layer 8a is formed by exposure and development, and (IV) the second pixel restricting layer 8b is formed by etching with the first pixel restricting layer 8a instead of the mask. Is possible.

  In this case, in the etching process (IV), the second pixel regulation layer 8b is removed from the central portion of the light emitting area LA. Therefore, the second pixel regulation layer 8b is controlled by controlling the etching process time. It can be formed in a shape protruding from the end P1 of the first pixel regulating layer 8a toward the light emitting area LA.

  By patterning the second pixel restricting layer 8b made of another material through the photosensitive resin patterned in this way (to be later used as the first pixel restricting layer 8a), complicated alignment such as alignment is performed. The first pixel regulation layer 8a and the second pixel regulation layer 8b made of a plurality of materials can be easily realized without going through the process. Since the photosensitive resin generally has high insulating properties, it is suitable as a material for the first pixel regulating layer 8a.

  Furthermore, by adjusting the patterning conditions of the photosensitive resin or the patterning of other materials, it is possible to realize complicated shapes such as making one size larger than the other size.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In addition, although the above example demonstrated the case where the pixel regulation layer 8a and the pixel regulation layer 8b were provided with respect to the anode 3 formed on the glass substrate 2 in the organic electroluminescent element 1, and the light emission area | region LA was regulated, Needless to say, the technical idea of Example 4 can be similarly applied to a structure in which the pixel restricting layer 8a and the pixel restricting layer 8b are provided on the cathode 7 formed on the glass substrate 2 to restrict the light emitting region LA. .

(Example 5)
FIG. 11 is an explanatory view showing the structure of the organic electroluminescence element 1 in Example 5 of the present invention. Hereinafter, the structure of the organic electroluminescence element 1 in Example 5 will be described in detail with reference to FIG. 11. However, the configuration and operation of an exposure apparatus to which the organic electroluminescence element 1 is applied and an image forming apparatus equipped with the exposure apparatus are described. Since there is no difference between them, the description is omitted.

  The organic electroluminescence device 1 in Example 5 has an anode 3 for injecting holes, a light emitting layer 6, a cathode 7 for injecting electrons, and a part of the anode 3 so as to control the injection of holes to control the light emitting layer. 6 has a plurality of layers (pixel restricting layer 8a and pixel restricting layer 8b) for restricting the light emitting area LA, and these pixel restricting layers are configured to make the light emission luminance in the light emitting area LA substantially uniform. is there. As shown in detail in FIG. 11, reference numeral 8 a denotes a first pixel regulating layer, which mainly has a function of ensuring overall insulation between the anode 3 and the cathode 7. Reference numeral 8b denotes a second pixel regulation layer, which mainly has a function for regulating the light emitting area LA. In this case, a material that covers the anode 3 and the cathode 7 with good insulation is used for the first pixel regulation layer 8a, and a material that can obtain accuracy such as thinness and fineness is used for the second pixel regulation layer 8b. It is desirable. Thus, it is possible to further enhance the function separation effect by using different materials for the first pixel regulating layer 8a and the second pixel regulating layer 8b.

  Further structural features of the organic electroluminescence element 1 of Example 5 are the first pixel regulating layer 8a formed in contact with the anode 3, and the first pixel regulating layer 8a formed in contact with the first pixel regulating layer 8a. 3 is configured from the second pixel regulating layer 8b covering a part of the third pixel.

  Hereinafter, the structure of the organic electroluminescence element 1 in Example 5 will be described in detail with reference to FIG. In the following description, for the sake of simplicity, the end on the light emitting area LA side in the first pixel restricting layer 8a is referred to as “the end P2 of the first pixel restricting layer 8a” (see P2 in the figure).

  First, the structure of the end portion P2 of the first pixel regulating layer 8a will be described.

  The angle θ3 formed between the surface of the anode 3 and the first pixel regulating layer 8a formed in contact with the anode 3 at the end portion P2 of the pixel regulating layer 8a is preferably 3 ° or more and 45 ° or less. More preferably, it is 10 degrees or less. In the fifth embodiment, the second pixel restricting layer 8b is disposed at a position sandwiched between the first pixel restricting layer 8a and the light emitting layer 6, so that the angle θ3 is directly set as described in detail in the second embodiment. This affects the uniformity of the thickness of the light emitting layer 6.

  However, in the fifth embodiment, since the second pixel regulating layer 8b covers the first pixel regulating layer 8a, the first pixel regulating layer 8a does not necessarily have a solvent such as toluene or xylene or an organic light emitting material that dissolves the organic light emitting material. It is not necessary to use a material exhibiting high wettability with respect to a solution in which the material is dissolved, and no treatment for maintaining the contact angle of the solvent or solution within a predetermined range with respect to the surface is required.

  In order to form the end portion P2 of the first pixel regulating layer 8a in a tapered shape, an etching method in which the type of etching gas or etchant, the etching time, and the etching mask are appropriately selected is applied in the case of forming by etching. The taper shape can be easily adjusted. In the case of forming by development using a photosensitive material, the taper shape can be easily adjusted by appropriately selecting the exposure time, exposure mask, development time and the like. In particular, the angle θ3 can be accurately adjusted by gradually expanding the etching region using a plurality of masks and controlling the thickness removed by etching by adjusting the etching time. In the fifth embodiment, the end portion P2 of the first pixel regulating layer 8a may be configured with a curved surface as in the third embodiment.

  As described in the first embodiment, the material constituting the pixel regulation layer is advantageously an opaque material. In Example 4, since the first pixel regulating layer 8a and the second pixel regulating layer 8b are functionally separated, the thickness of the first pixel regulating layer 8a is set to a relatively large value of about 5 micrometers, and By configuring the first pixel regulation layer 8a with an organic substance such as polyimide whose carbon particle dispersion amount is controlled to be relatively low, both insulation and low light transmittance required for the first pixel regulation layer 8a can be achieved. Is possible.

  Next, the second pixel regulating layer 8b will be described in detail.

  The second pixel regulating layer 8b mainly has a function of regulating the light emitting area LA, and it is necessary to ensure wettability with respect to the light emitting layer 6 as already described in other embodiments. In order to satisfy this requirement, it is desirable that the second pixel regulation layer 8b is made of, for example, SiN or AlN. These materials are superior in terms of insulation, pixel regulation accuracy, etc., and are excellent in wettability with the above-mentioned solvent or solution as the material itself. The contact angle with the solvent or solution at the end P2 of the second pixel regulating layer 8b is 45 degrees or less by performing sufficient cleaning, ultraviolet irradiation, heat treatment, plasma treatment, etc. after the pixel regulating layer 8 is formed. Therefore, sufficient wettability with respect to the light emitting layer 6 can be ensured.

  As already described in the first embodiment, the step between the anode 3 and the second pixel regulation layer 8b is desirably 0.05 micrometers or more and 2 micrometers or less, and the thickness of the second pixel regulation layer 8b is 0.05. It is more desirable that the thickness is not less than micrometer and not more than 0.5 micrometer. On the other hand, it is desirable that the thickness of the first pixel regulating layer 8b is, for example, about 5 micrometers to ensure insulation. That is, the thickness of the first pixel restricting layer 8a and the thickness of the second pixel restricting layer 8b are configured to satisfy the relationship of “the thickness 8a of the first pixel restricting layer> the thickness 8b of the second pixel restricting layer”. It is desirable to do.

  The second pixel restricting layer 8b may be made of metal. When the second pixel regulating layer 8b is made of metal, the light transmittance can be substantially zero as already described in the first embodiment. Therefore, when a metal is employed as the second pixel restriction layer 8b, the first pixel restriction layer 8a may be configured without being particularly conscious of light transmittance.

  In Example 5, since the first pixel regulating layer 8a is made of an insulating material so as to provide insulation between the anode 3 and the cathode 7, the "light emitting layer 6 has holes in the light-emitting layer 6 required in Example 1". It is not necessary to satisfy the condition of “a metal that is difficult to be injected”. Therefore, in Example 5, any metal material can be used as long as the patterning property is satisfied.

  However, as shown in FIG. 11, the second pixel regulation layer 8 b is provided independently in each organic electroluminescence element 1, but the second pixel regulation layer 8 b straddles a plurality of organic electroluminescence elements 1. (I.e., it is formed in a solid state and has an opening at a predetermined position of the anode 3), a metal material having a low resistance value is used because a drive current leaks to an adjacent pixel. Then you can't. In this case, it is desirable to use a conductive material having a predetermined resistance value such as a metal oxide or a nitride as the second pixel regulation layer 8b. Specifically, MoO3 can be used for a metal oxide, and SiN can be used for a nitride. Further, in this case, the leakage current can be prevented if the conductivity in the plane direction is 1 megaohm or more. In order to further improve the effect of suppressing the leakage current, it is desirable that the conductivity in the surface direction be further 10 megaohms or more.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In addition, although the above example demonstrated the case where the pixel regulation layer 8a and the pixel regulation layer 8b were provided with respect to the anode 3 formed on the glass substrate 2 in the organic electroluminescent element 1, and the light emission area | region LA was regulated, Needless to say, the technical idea of the fifth embodiment can also be applied to the structure in which the pixel regulating layer 8a and the pixel regulating layer 8b are provided to the cathode 7 formed on the glass substrate 2 to regulate the light emitting area LA. .

(Example 6)
FIG. 12 is an explanatory view showing the structure of the organic electroluminescence element 1 in Example 6 of the present invention. Hereinafter, the structure of the organic electroluminescent element 1 in Example 6 will be described in detail with reference to FIG. 12. However, the configuration and operation of the exposure apparatus to which the organic electroluminescent element 1 is applied and the image forming apparatus equipped with the exposure apparatus are described. Since there is no difference between them, the description is omitted.

In FIG. 12, 8b is the 2nd pixel control layer provided in the surface of the anode 3, for example, is comprised from the inorganic oxide or amorphous carbon formed with the thickness of 5 nanometers to 10 nanometers. The inorganic oxide can be used, for example _{MoO 3, V 2 O 5,} WO 3, TiO 2, SiO, MgO or the like.

  In the organic electroluminescence element 1 shown in Example 6, the second pixel restricting layer 8b is formed on the surface of the anode 3 by vapor deposition or the like, and is in contact with the second pixel restricting layer 8b and has a high insulating property. A pixel restricting layer 8a is provided, and the light emitting region LA is restricted by the first pixel restricting layer 8a, and the light emitting layer 6 and the cathode 7 are laminated.

  With such a structure, the first pixel regulating layer 8a has an insulating function as an original pixel regulating layer, and the second pixel regulating layer 8b has a minute size of the light emitting layer 6 in the light emitting region LA. A function to absorb unevenness and make the thickness uniform can be provided.

  Further, by setting the thickness of the second pixel regulation layer 8b to 10 nanometers or less, the second pixel regulation layer 8b can be configured without hindering charge injection from the anode 3 to the light emitting layer 6.

  As described in Example 2 as the first pixel regulating layer 8a, a solvent such as toluene or xylene that dissolves the organic light emitting material or a material that exhibits high wettability with respect to a solution in which the organic light emitting material is dissolved is used. Further, by treating the surface of the first pixel regulating layer 8a to make the contact angle with the solvent or solution 45 degrees or less, the thickness of the light emitting layer 6 is made uniform in the first pixel regulating layer 8a. It is possible to provide an insulating function as the original pixel restricting layer while providing a function, and to provide the second pixel restricting layer 8b with a function such that the thickness of the light emitting layer 6 in the light emitting region LA is uniform. it can. Further, the angle θ4 formed by the surface of the second pixel restricting layer 8b and the first pixel restricting layer 8a at the end P3 of the first pixel restricting layer 8a illustrated in FIG. 12 is also described in the second embodiment. The angle is preferably 3 degrees or more and 45 degrees or less, more preferably 3 degrees or more and 10 degrees or less.

  In the case where the second pixel regulation layer 8b is uniformly formed on the surface of the anode 3, if the first pixel regulation layer 8a has sufficient insulating properties, it is at most 10 nanometers as described above. The second pixel restricting layer 8b, which is only a thickness, has sufficient insulation with respect to the adjacent organic electroluminescence element 1, and therefore the second pixel restricting layer 8b is selectively applied to a portion corresponding to the light emitting region LA. There is no need to form. In this way, a pixel regulation layer having a plurality of functions can be easily formed without using a complicated process.

  Further, in the sixth embodiment, for example, as described in the third embodiment, the shape of the end portion P3 of the first pixel regulating layer 8a may be a curved surface. Further, as described in the fourth and fifth embodiments, a plurality of shapes may be used. You may use the pixel control layer which consists of layers.

  With the configuration as described above, the thickness of the light emitting layer 6 in the light emitting region LA is made uniform, and the distribution of the light emission luminance of the light emitted from the light emitting region LA can be made uniform.

  In addition, although the above example demonstrated the case where the pixel regulation layer 8a and the pixel regulation layer 8b were provided with respect to the anode 3 formed on the glass substrate 2 in the organic electroluminescent element 1, and the light emission area | region LA was regulated, It goes without saying that the technical idea of Example 6 can be similarly applied to a structure in which the pixel restricting layer 8a and the pixel restricting layer 8b are provided on the cathode 7 formed on the glass substrate 2 to restrict the light emitting area LA. .

  As described above by using a plurality of embodiments, the organic electroluminescence element 1 of the present invention can make the light emission luminance in the light emission region LA regulated by the pixel regulation layer 8 substantially uniform. Therefore, the exposure apparatus using the organic electroluminescence element 1 of the present invention as a light source can obtain an electrostatic latent image having a desired shape.

  Further, the organic electroluminescence element 1 of the present invention has a variation in the thickness of the light emitting layer 6 in the light emitting region regulated by the pixel regulating layer 8 (or the first pixel regulating layer 8a and the second pixel regulating layer 8b). Since the thickness of the light emitting layer is 20% or less of the average value and the thickness of the light emitting layer 6 is uniform, the current distribution flowing through the organic electroluminescent element 1 is uniform. Accordingly, since the deterioration of the light emitting region LA of the organic electroluminescence element 1 becomes uniform, the exposure apparatus capable of forming a latent image that is substantially long in life and stable over a long period of time can be provided. . Furthermore, since the organic electroluminescence element 1 of the present invention emits light uniformly in the light emitting area LA, it is not necessary to emit light unnecessarily brightly in order to obtain a desired light emission luminance, and an exposure apparatus with low power consumption can be realized.

  In the image forming apparatus to which the exposure apparatus of the present invention is applied, since the exposure apparatus stably forms a latent image for a long period of time, a long-life image forming apparatus can be realized. Further, since the exposure apparatus can be obtained by a simple construction method, the image forming apparatus can be provided at a low price. Further, in the image forming apparatus using the exposure apparatus of the present invention, a desired electrostatic latent image can be obtained, so that a high quality image can always be formed. Further, the size of the exposure apparatus can be reduced by adopting the organic electroluminescence element 1 as a light source, and a compact image forming apparatus can be realized by mounting this exposure apparatus.

  Now, by uniformly forming the light emitting layer 6 in the light emitting region LA of the organic electroluminescent element 1, the organic electroluminescent element 1 that emits light stably can be realized. This is conspicuous in the organic electroluminescence device 1 in which the portion is made of a polymer material or in the organic electroluminescence device 1 in which at least a part of the light emitting layer 6 is made of a material soluble in a solvent. When forming an organic electroluminescence element using these materials, a method of forming a film in a state of being dissolved in a solvent without using a method such as vapor deposition is used. Thickness non-uniformity due to the wettability to the solvent such as toluene and xylene that dissolves the organic light-emitting material, or the solution dissolving the organic light-emitting material, and the capillary phenomenon or surface tension due to the structure. Since it is high, the effect of the present invention can be obtained more remarkably.

  As for the light-emitting layer forming method, the inkjet method and the like are formed by actively utilizing surface tension and the water repellency of the pixel regulating layer 8, while the spin coating method, the gap method, and the flood printing method (inkjet method). In the uniform coating method such as the uniform coating method used and the screen printing method, since the material such as the light emitting layer is uniformly coated, the effect of the present invention appears more remarkably. These methods are often used in the case of a monochromatic light-emitting layer that does not require separate coating of the light-emitting layer, and the present invention has a more effective effect when these methods or structures are used.

  In the above description, the organic electroluminescence element 1 in the exposure apparatus has been described on the assumption that it is driven by a DC power source, but may be driven by an AC power source or a pulse power source.

  The organic electroluminescence element of the present invention, the exposure apparatus using the same, and the image forming apparatus are used in various apparatuses that require uniform emission luminance in the light emitting region of the organic electroluminescence element or stable light emission over a long period of time. For example, the present invention can be applied to a copying machine, a multifunction printer, a printer, a facsimile, and the like. In addition, since organic electroluminescent elements can obtain the three primary colors of red, green, and blue by selecting an organic light emitting material, for example, if an exposure device that exposes each color of RGB is used, an image of a type that directly exposes photographic paper. It can also be applied to a forming apparatus.

Explanatory drawing which shows the structure of the organic electroluminescent element in Example 1 of this invention Configuration diagram of exposure apparatus in embodiment 1 (A) is a top view of the glass substrate which concerns on the exposure apparatus of Example 1, (b) is the principal part enlarged view. Circuit diagram related to exposure apparatus of embodiment 1 Sectional drawing of the organic electroluminescent element and drive circuit which concern on the exposure apparatus of the Example 1 Configuration diagram of an image forming apparatus equipped with an exposure apparatus to which the organic electroluminescence element of Example 1 is applied 1 is a configuration diagram showing the periphery of a developing station in the image forming apparatus according to the first embodiment. Explanatory drawing which shows the structure of the organic electroluminescent element in the Example 2 Explanatory drawing which shows the structure of the organic electroluminescent element in the Example 3 Explanatory drawing which shows the structure of the organic electroluminescent element in the Example 4 Explanatory drawing which shows the structure of the organic electroluminescent element in Example 5 Explanatory drawing which shows the structure of the organic electroluminescent element in Example 6 Sectional drawing which shows the structure of the conventional organic electroluminescent element Sectional drawing which shows the structural example of the conventional organic electroluminescent element Sectional drawing which shows the structural example of the conventional organic electroluminescent element Explanatory drawing which shows distribution of the light emission luminance in the light emission area | region of the conventional organic electroluminescent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic electroluminescent element 2 Glass substrate 3 Anode 6 Light emitting layer 7 Cathode 8, 8a, 8b Pixel control layer 11 Organic electroluminescent element 12 Glass substrate 13 Anode 14 Hole transport layer 15 Organic material layer 16 Light emitting layer 17 Cathode 18, 18a , 18b Pixel regulating layer 21 Image forming device 22, 22Y, 22M, 22C, 22K Developing station 28, 28Y, 28M, 28C, 28K Photosensitive member 33, 33Y, 33M, 33C, 33K Exposure device 71 Lens array 77 Light quantity sensor unit 81 Source driver 82 TFT circuit 84 Sealing glass 102 TFT

Claims (40)

An anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and a pixel regulating layer for controlling the injection of at least one of the holes or the electrons to regulate the light emitting region of the light emitting layer. The organic electroluminescence device is characterized in that the pixel regulation layer is configured so that light emission luminance in the light emitting region is substantially uniform. 2. The organic electroluminescence device according to claim 1, wherein the pixel regulating layer is made of an opaque material. The organic electroluminescence device according to claim 2, wherein the pixel regulation layer contains carbon particles. When the work function of the pixel restricting layer is W _F1 and the work function of the anode is W _F2 , the pixel restricting layer is made of a metal material satisfying a work function W _F1 of 2.0 [eV] <WF ₁ <WF _2. The organic electroluminescence device according to claim 2, wherein the organic electroluminescence device is configured. 2. The organic electroluminescence according to claim 1, wherein the light emission luminance in the light emitting region is substantially uniform according to an angle formed between a surface of the anode or the cathode and a surface of the pixel regulating layer in contact therewith. element. 6. The organic electroluminescence device according to claim 5, wherein an angle formed by the surface of the anode or the cathode and the surface of the pixel regulating layer in contact with the surface is 3 degrees or more and 45 degrees or less. 7. The organic electroluminescence device according to claim 6, wherein an angle formed by the surface of the anode or the cathode and the surface of the pixel regulating layer in contact with the surface is 3 degrees or more and 10 degrees or less. 2. The organic electroluminescence device according to claim 1, wherein the thickness of the pixel regulating layer is smaller than the width of the light emitting region and 1.5% or more of the width of the light emitting region. 2. The organic electroluminescence element according to claim 1, wherein a side of the pixel regulation layer that regulates the light emitting region is configured by a curved surface that decreases in thickness toward an end. 10. The organic electroluminescence according to claim 9, wherein a side of the pixel regulation layer that regulates the light emitting region is configured by a curved surface that protrudes downward with respect to a surface of the anode or the cathode in contact with the pixel regulation layer. element. 2. The organic electro luminescence device according to claim 1, wherein the pixel regulating layer is made of a solvent that dissolves a light emitting material constituting the light emitting layer or a material that has wettability with respect to a solution in which the light emitting material is dissolved. Luminescence element. 12. The organic electroluminescence device according to claim 11, wherein a contact angle with the solvent or the solution on the side of restricting the light emitting region in the pixel restricting layer is set to 45 degrees or less. An anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and covering the anode or a part of the cathode to control injection of at least one of the holes or the electrons to control the light emitting layer. An organic electroluminescence element comprising: a pixel restricting layer composed of a plurality of layers for restricting a light emitting region, wherein the pixel restricting layer is configured so that light emission luminance in the light emitting region is substantially uniform. The organic electroluminescence element according to claim 13, wherein each layer of the pixel regulation layer is made of a different material. A first pixel regulating layer formed in contact with the anode or the cathode; and a second layer formed in contact with the first pixel regulating layer and covering a part of the anode or the cathode. 14. The organic electroluminescence device according to claim 13, wherein the organic electroluminescence device is composed of a pixel regulation layer. 16. The organic electroluminescence device according to claim 15, wherein an angle formed between the surface of the anode or the cathode and the surface of the first pixel regulation layer in contact with the surface is 3 degrees or more and 45 degrees or less. The organic electroluminescence device according to claim 16, wherein an angle formed by a surface of the anode or the cathode and a surface of the first pixel regulating layer in contact with the surface is 3 degrees or more and 10 degrees or less. The pixel restricting layer is formed in contact with the second pixel restricting layer formed in contact with the anode or the cathode, and covers a part of the second pixel restricting layer formed in contact with the second pixel restricting layer. The organic electroluminescence element according to claim 13, comprising a first pixel regulating layer. 19. The organic electroluminescence according to claim 18, wherein an angle formed between a surface of the second pixel regulation layer and a surface of the first pixel regulation layer in contact with the second pixel regulation layer is 3 degrees or more and 45 degrees or less. element. 20. The organic electroluminescence according to claim 19, wherein an angle formed between the surface of the second pixel regulating layer and the surface of the first pixel regulating layer in contact with the second pixel regulating layer is 3 degrees or more and 10 degrees or less. element. 19. The organic electroluminescence device according to claim 18, wherein the first pixel restricting layer is made of a photosensitive resin, and the second pixel restricting layer is patterned by the first pixel restricting layer. . The thickness of the first pixel restricting layer and the thickness of the second pixel restricting layer are configured to satisfy the relationship of the thickness of the first pixel restricting layer> the thickness of the second pixel restricting layer. The organic electroluminescent element according to claim 15 or claim 18. 19. The organic electroluminescence element according to claim 18, wherein the thickness of the first pixel regulating layer is configured to be equal to or less than a width of the light emitting region and 1.5% or more of a width of the light emitting region. 19. The organic electroluminescence element according to claim 15, wherein the first pixel regulation layer is made of an opaque material. The organic electroluminescence device according to claim 24, wherein the first pixel regulation layer contains carbon particles. 16. The structure of claim 15, wherein at least the second pixel regulating layer is made of a solvent that dissolves a light emitting material that constitutes the light emitting layer, or a material that has wettability with respect to a solution in which the light emitting material is dissolved. Or the organic electroluminescent element of Claim 18. 27. The organic electroluminescence device according to claim 26, wherein a contact angle of at least the second pixel regulating layer with the solvent or the solution is 45 degrees or less. The organic electroluminescence element according to claim 15 or 18, wherein the first pixel regulation layer is made of an organic material, and the second pixel regulation layer is made of an inorganic material. 19. The organic material according to claim 15, wherein the first pixel restriction layer is made of an insulating material, and the second pixel restriction layer is made of a conductive material having a predetermined resistance value. Electroluminescence element. 30. The organic electroluminescence element according to claim 29, wherein a resistance value in a plane direction of the conductive material is 1 megaohm or more. The organic electroluminescence element according to claim 15 or 18, wherein the first pixel regulation layer is made of an insulating material, and the second pixel regulation layer is made of a metal material. 19. The organic electroluminescence element according to claim 15, wherein the second pixel regulation layer is made of silicon nitride or aluminum nitride. 14. The organic electroluminescent device according to claim 1, wherein the anode includes a layer composed of at least a hole transport material. 34. The organic electroluminescence device according to claim 33, wherein the hole transport material is an inorganic oxide or amorphous carbon. 14. The organic electroluminescence device according to claim 1, wherein the light emitting layer is made of a material soluble in a solvent. 14. The organic electroluminescent element according to claim 1, wherein the light emitting layer is made of a polymer material. 14. The organic electroluminescence device according to claim 1, wherein the light emitting layer is formed by a spin coating method. An anode for injecting holes, a light emitting layer, a cathode for injecting electrons, and a pixel regulating layer for controlling the injection of at least one of the holes or the electrons to regulate the light emitting region of the light emitting layer. The variation in the thickness of the light emitting layer in the light emitting region regulated by the pixel regulating layer is 20% or less of the average value of the thickness of the light emitting layer in the light emitting region. element. The organic electroluminescent elements according to any one of claims 1 to 38 are arranged in a line, and each organic electroluminescent element is configured to be independently controlled to be turned on / off. apparatus. 40. An image forming apparatus comprising: at least an exposure apparatus according to claim 39; a photoconductor on which an electrostatic latent image is formed by the exposure apparatus; and a developing unit that visualizes the electrostatic latent image formed on the photoconductor. .

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