JP2003045658A - El element and display medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL element having a high productive efficiency, being inexpensive, and capable of showing a pattern of photographs, pictures, or characters with fine pixels, and a display medium using it. SOLUTION: In the EL element including at least a base material, an anode layer, a light-emitting layer, and a cathode layer, the light-emitting layer is characterized in that an image separated into two or more colors is formed when light-emitting materials that emit the different colors are printed in the shape of dots. The image is separated into three primary colors of the light, red, green and blue.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL device, and more particularly to an EL device for displaying a still image such as a specific character, pattern or photograph. In particular, it relates to a display medium such as a greeting card.

[0002]

2. Description of the Related Art Conventionally, when a display element using an electroluminescence element is used to illuminate a design or a character, E
A method in which an L element is used as a backlight to illuminate a design and characters and a method in which a light emitting material is formed into a design and a character pattern have been used. However, in the former method, a clear luminescent image cannot be obtained because only a picture, a photograph, a character, etc. are watermarked through the backlight. In the latter case, the light emitting layer of a desired color is separately painted for each large pattern to form characters, patterns, etc., and therefore, delicate gradation with a gradation like a photograph or a fine picture is formed. The design could not be expressed.

There is also a method in which a red, green, and blue light-emitting material is formed in a dot matrix type and is controlled by a TFT to express a clear image, but this is mainly for expressing a moving image. is there. You can't express a picture or a picture as a still image, but it's very expensive.

Therefore, a card capable of displaying a fine still image such as a photograph on a display medium using an EL element,
It has been difficult to inexpensively manufacture display media such as posters.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an EL element which has high production efficiency, is inexpensive, and can express a pattern such as a photograph, a picture, and a character with fine pixels, and a display medium using the EL element. .

[0006]

According to a first aspect of the present invention, in an EL device including at least a base material, an anode layer, a light emitting layer, and a cathode layer, the light emitting layer has an image in which two or more colors are separated. The EL element is formed by printing a light-emitting material that emits light of each color in a dot or dot shape.

According to a second aspect of the present invention, the light emitting layer is red,
The EL element according to claim 1, wherein the EL element is color-separated into blue and green.

According to a third aspect of the invention, the light emitting layer is red,
3. The EL device according to claim 2, wherein the EL device is formed of halftone dots of green and blue light emitting materials and is arranged linearly at equal intervals.

The invention according to claim 4 is the EL element according to claim 2 or 3, characterized in that the size of the halftone dot is adjusted to impart a shade of color.

According to a fifth aspect of the invention, the light emitting material is red,
2. The EL according to claim 1, wherein the green and blue dots are randomly arranged, and the dark areas are densely formed and the light areas are sparse by an FM screening method.
It is an element.

The invention according to claim 6 is the EL element according to any one of claims 1 to 5, characterized in that the dots or dots of the red, green and blue light emitting materials do not overlap each other.

The invention of claim 7 is the EL element according to any one of claims 1 to 6, wherein an overcoat layer containing a conductive substance is laminated on the light emitting layer.

The invention according to claim 8 is the EL element according to any one of claims 1 to 7, characterized in that a black shielding layer is further provided on the surface of the light emitting layer opposite to the display surface side. .

The invention according to claim 9 is characterized in that the light emitting material is printed by an offset printing method or a gravure printing method.
It is an element.

A tenth aspect of the present invention is a display medium using the EL element according to any one of the first to ninth aspects.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an EL device comprising at least a base material, an anode layer, a light emitting layer and a cathode layer in order to accurately display a clear image such as a photograph or a picture.
It is characterized in that an original such as a picture is color-separated into two or more colors, and a light-emitting material that emits light of each color is printed as a light-emitting layer by a printing method. Less than,
The present invention will be described in detail.

The EL device of the present invention comprises at least a base material, an anode layer, a light emitting layer and a cathode layer. If necessary, a hole transport layer and a light emitting layer may be provided between the anode layer and the light emitting layer. A charge transport layer may be provided between the cathode layers, and a black shielding layer may be provided on the side opposite to the display side. The shielding layer may be between the light emitting layer and the cathode, or may be outside the cathode. The hole transport layer and the electron transport layer may be laminated separately from the light emitting layer, or may be mixed with the light emitting layer and laminated. In addition, each structure is formed by stacking layers in order from the base material.

First, a method of forming a light emitting layer, which is a feature of the present invention, will be described. First, color-separate originals such as photos, pictures, illustrations, and characters that you want to display. Although a known method can be used for the color separation method, specifically, a method using a color scanner is generally used. According to this method, the original taken in passes through a color filter and the light passing therethrough is converted into an electric signal to be separated into two or more colors. At this time, color correction may be performed at the same time. Further, there are methods such as a drum type and a flat type scanner in this color scanner, but the color scanner can be used properly according to the application. When two or more colors and three primary colors of light are used on a computer after being decomposed into indigo, red, yellow, and black used for printing by this color scanner or the like, they may be converted into red, green, and blue. Also,
Instead of using a scanner or the like, a color original may be photographed by passing through a filter having a color complementary to the desired color, and a negative or positive color-separated may be created, and then a plate of the desired color may be created. Specifically, a blue plate may be prepared using a yellow filter, a green plate may be prepared using a red filter, and a red plate may be prepared using an indigo filter. Further, in the present invention, not only printed matter or photograph originals, but also CG image data created on a computer and image data such as photographs and illustrations previously loaded in the computer may be color-separated on the computer.

Since the EL element expresses an image with a light emitting body, it is preferable that the color separation is performed by separating the three primary colors of light into red, green and blue. Further, in order to represent black, an insulating layer may be simply provided as a non-light emitting portion, but by providing a black shielding layer that blocks light on the side opposite to the display side of the light emitting layer, it is possible to obtain better contrast. Become. Further, in order to express black or dark color, a black pigment or dye may be printed as the dark color portion of the image.

Next, a plate is made for each color separated by the above method, and the light emitting material is printed by the printing method using each plate. As the printing method, various methods can be used depending on the purpose. For example, there are a flexographic printing method, an offset printing method and a gravure printing method. If offset printing is used, fine printing can be performed and a sharp display can be obtained. The durability of the plate is high if it is gravure printing. Further, in the gravure printing, the conventional gravure method is a method of expressing the gradation of an image by the amount of the light emitting material depending on the depth of the plate and can be preferably used.

The method of forming the respective colors is not particularly limited, and for example, as shown in FIG. 3, the respective light emitting materials may be arranged linearly so that the respective colors do not overlap. This method is preferable because the light emitting materials do not overlap with each other, so that problems such as absorption of light emission do not occur and the light emission can be easily controlled. Further, in this method, the shade of color is adjusted by adjusting the size of the halftone dots of the light emitting material. The size here means the size and / or thickness of the halftone dots of the light emitting material.

There are mainly two types of methods for forming the respective colors of red, green and blue. One is a method of forming the dots by orderly and linearly arranged at equal intervals for each color (AM screening method). ). In this method, the shade of color is adjusted by adjusting the size of the halftone dots. The other is a method of randomly arranging dots of the same size for each color and adjusting the density of the color by the density. The red,
The green and blue halftone dots may be formed by shifting their angles by 30 °. Further, since the respective light emitting materials are overlapped by these methods, it is preferable that among the light emitting materials, the light emitting material laminated on the display side has an absorption wavelength different from that of other light emitting materials. Then, the light emitting material on the display side does not absorb the light emitted from other light emitting materials, and the emission color is easily controlled.

As a light emitting material, if the required performance is satisfied,
Although any type can be used, an organic type, particularly a polymer type is preferable. Coumarin-based, perylene-based, pyran-based, anthuron-based, porphyrene-based, quinacridone-based, N, N'-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole-based fluorescent dyes such as polystyrene, It is possible to use a substance dissolved in a polymer such as polymethylmethacrylate or polyvinylcarbazole, or a polymer light emitter such as a polyarylene-based or polyarylvinylene-based polymer. By using a polymer as the light emitting layer, an EL device having high mechanical strength and high durability and long life can be provided.

As the black shielding layer, a dye such as aniline black or other black pigment or ink is dissolved and dispersed in a suitable solvent, and spin coating, flexography, gravure, microgravure, coating such as offset coating,
The film can be formed by using a printing method. It may also contain a conductive substance.

An overcoat layer containing a conductive substance may be laminated on the light emitting material. This allows
The flatness of the printed surface is increased, and the short circuit of the cathode can be prevented. Further, in order to make the applied voltage more uniform, it is preferable to use a substance having the same conductivity as the light emitting material. Further, for the same purpose, an electron transport layer may be used instead of the overcoat layer.

Next, a method of laminating other layers will be described.
The base material is not particularly limited, and any material such as glass and resin film can be used. Since a resin film is flexible and transparent, it can be used as a display medium for cards, posters, telegrams and the like, and is preferable. Polyethylene terephthalate (PE
T), polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethylmethacrylate, polycarbonate and the like can be used.
Further, a ceramic vapor deposition film or a gas barrier film such as polyvinylidene chloride or polyvinyl chloride may be laminated on the surface on which the anode layer is not provided.

The anode layer is preferably transparent or semitransparent, and known ones can be used. For example, a composite oxide of indium and tin (ITO) can be used. Further, as a stacking method, a vapor deposition method, a sputtering method, or the like can be used. The anode layer may be formed on the entire surface or may be patterned.

When a hole transport layer is provided, copper phthalocyanine or its derivative, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N'-diphenyl-N, N'-bis ( 3-methylphenyl) -1,1 '
-Biphenyl-4,4'-diamine, N, N'-di (1
Low molecules such as aromatic amines such as -naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine can also be used, but polyaniline, polythiophene, polyvinylcarbazole, poly ( A polymer material such as a mixture of 3,4-ethylenedioxythiophene) and polystyrene sulfonic acid is more preferable because the film can be formed by a wet method.

When an electron transport layer is provided, 1,3,5-
Small molecules such as oxadiazole derivatives such as tris (4-tert-butylphenyl-1,3,4-oxadiazole) benzene (TPOB), 8-quinolinol derivatives such as tris (8-quinolinol) aluminum, or metal complexes thereof are also available. Although it can be used, a polymer material such as poly (pyridine-2,5-diyl), poly (quinoline-5,8-diyl), and poly (quinoxaline-5,8-diyl) can be formed into a film by a wet method. Possible and more preferable.

The hole transporting layer, the polymer light emitting layer and the electron transporting layer may be formed of toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, water, etc., alone or The polymer material can be dissolved in a mixed solvent, and a film can be formed using a coating method such as spin coating, spray coating, flexo, gravure, microgravure, intaglio offset, or a printing method. The use of the wet method as described above is preferable because it has high production efficiency and can be manufactured at low cost. If necessary, a surfactant, an antioxidant, a viscosity adjusting agent, an ultraviolet absorber, etc. may be added. These film thicknesses are 1000 nm or less in total even in the case of laminating a single layer or a plurality of layers, and preferably 50 to 150 nm.

As the cathode layer, Mg, Al, Yb, Ca,
A simple metal such as Ba is used, or a compound such as Li or LiF is sandwiched by about 1 nm at the interface in contact with the light emitting medium, and Al or Cu having high stability and conductivity is laminated and used. Alternatively, in order to achieve both electron injection efficiency and stability, an alloy system of a metal having a low work function and a stable metal, such as MgAg,
Alloys such as AlLi and CuLi can be used. Depending on the material, the cathode is formed by resistance heating vapor deposition, electron beam method,
A sputtering method can be used. The thickness of the cathode is preferably about 10 nm to 1000 nm. Further, the cathode layer may be formed on the entire surface or may be patterned.

In the EL device of the present invention, by using a long flexible substrate as the substrate, the anode layer, the polymer EL layer and the light absorbing layer are continuously wound while the substrate is continuously unwound. It is possible to form a layer and a cathode layer, and finally wind the substrate and cut it into a predetermined size. At this time, the anode layer can be formed by the vapor deposition or sputtering method or the coating pyrolysis method as described above, and the light emitting layer and the black shielding layer can be formed by the printing method as described above, or the cathode. The layer can be formed by the vapor deposition method, the electron beam method, the sputtering method, or the like as described above. Moreover, a hole transport layer and / or an electron transport layer can be included if necessary. In this way, the polymer EL is continuously manufactured mainly by the wet method.
By forming layers, the production efficiency can be increased and the EL element can be provided at low cost.

[0033]

EXAMPLES The present invention will be described in detail below with reference to examples. <Example 1> An ITO film 2 was formed as an anode layer on a substrate 1 made of PET by a sputtering method. Next, the light emitting layer was formed by the following method. First, an original photograph was photographed with a drum scanner, converted into electrical signal data, and then color-separated into red, green, and blue on a computer. Based on the color-separated data, red, green, and blue gravure printing plates were prepared, and the luminescent layers of each color were printed by gravure printing using the respective plates. It should be noted that poly (3-hexylthiophene) was used as the red light emitting material, poly (3-cyclohexylthiophene) was used as the green light emitting material, and poly (octylfluorene) was used as the blue light emitting material.
It was formed with a film thickness of m. As shown in FIG. 5, the color-separated light-emitting layer was formed so that red, green, and blue halftone dots were linearly arranged so as not to overlap each other. Next, a black shielding layer was formed by dissolving aniline black in a toluene solution to a thickness of 20 nm by spin coating. Next, MgAg was formed as a cathode layer by binary co-evaporation with a film thickness of 200 nm.

When a voltage of 5 V was applied to the obtained EL device, an average emission of 100 cd / m ² was obtained, and a clear still image similar to that of the original original photograph was obtained.

<Embodiment 2> The original is color-separated by the same procedure as in Embodiment 1, each luminescent material is formed by halftone dots, and each luminescent material of each color is formed by a gravure printing method while shifting an angle of 30 °. Was printed with a film thickness of 30 nm. Further, instead of the overcoat layer, sodium polystyrene sulfonate was formed into a film having a film thickness of 50 nm by a spin coating method instead of the overcoat layer. Next, a black shielding layer was formed by dissolving aniline black in a toluene solution to a thickness of 20 nm by spin coating. Next, as a cathode layer, MgAg is formed into a 20 layer film by binary co-evaporation.
It was formed with a film thickness of 0 nm.

When a voltage of 5 V was applied to the obtained EL device, an average emission of 50 cd / m ² was obtained, and the same still image as the photograph of the original document was obtained.

Example 3 The same procedure as in Example 2 was carried out except that the light emitting material was formed into dots for each color. When a voltage of 5 V was applied to the obtained EL device, light emission of 50 cd / m ^{2 on} average was obtained, and the same still image as the photograph of the original document was obtained.

[0038]

According to the present invention, image data of an original is color-separated, a printing plate is prepared for each separated color, and a luminescent material is printed for each color to form a luminescent layer.
EL devices with clear still images can be produced inexpensively.

[0039]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an EL element of the present invention.

FIG. 2 is a cross-sectional view showing another structure of the EL element of the present invention.

FIG. 3 is another printing example (3) of the light emitting material of the EL device of the present invention.
It is explanatory drawing which shows (color component).

FIG. 4 is an explanatory view showing one printing example (one color) of the light emitting material of the EL device of the present invention.

FIG. 5 is another printed example (1) of the light emitting material of the EL device of the present invention.
It is explanatory drawing which shows (color component).

[Explanation of symbols]

1 base material 2 anode 3 Luminescent material 3A Luminescent material A 3B Luminescent material B 3C Luminescent material C 4 Overcoat layer (electron transport layer) 5 Shield layer 6 cathode

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/22 H05B 33/22 ZF term (reference) 3K007 AB04 AB17 AB18 BA07 CA06 CB01 CC02 DA01 DB03 EB00 FA01 5C096 AA01 AA27 BA04 CA06 CA12 CA29 CB07 CC07 CC24 EA06 EB02 EB16 FA01 FA02

Claims (10)

[Claims] 1. An EL device comprising at least a base material, an anode layer, a light emitting layer and a cathode layer, wherein the light emitting layer emits an image in which two or more colors are separated into halftone dots. Alternatively, an EL element is formed by printing in a dot shape. 2. The EL device according to claim 1, wherein the light emitting layer is color-separated into red, green and blue. 3. The EL device according to claim 2, wherein the light emitting layer is formed of halftone dots of red, green, and blue light emitting materials and is arranged linearly at equal intervals. . 4. By adjusting the size of the halftone dots,
The EL element according to any one of claims 1 to 3, wherein the EL element is colored. 5. The light emitting material is formed by an FM screening method in which red, green, and blue dots are randomly arranged, and dark areas are dense and light areas are sparse. The EL device according to claim 1. 6. The halftone dots or dots of the red, green and blue light emitting materials do not overlap each other.
The EL device according to any one of 1. 7. An overcoat layer containing a conductive substance is laminated on the light emitting layer.
The EL device according to any one of 1. 8. The surface of the light emitting layer opposite to the display surface side,
The EL element according to claim 1, further comprising a black shielding layer. 9. The EL device according to claim 1, wherein the light emitting material is printed by an offset printing method or a gravure printing method. 10. A display medium using the EL element according to claim 1.