JP2008040400A - Development device, image forming apparatus using the same, developer carrier, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development device where attention is payed to the circumferential face of a developer carrier for carrying and conveying a two component carrier, and the stable circumferential face can be obtained over a long period, to provide an image forming apparatus using the same, to provide a developer carrier, and to provide a method for producing the same. <P>SOLUTION: Regarding the development device where a developer carrier 2 arranged so as to be confronted with an image carrier 1 is provided, and a two component developer comprising toners and carriers is carried and conveyed by the developer carrier 2; in the developer carrier 2, a fine roughened face 3 which can carry the developer is formed at the circumferential face, and the surface projecting part 3a of the fine roughened face 3 is made into the smooth face 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer, and in particular, a developing device using a two-component developer containing toner and a carrier, an image forming apparatus using the same, and a two-component development. The present invention relates to an improvement of a developer carrying member capable of carrying an agent and a method for producing the same.

In general, in a two-component development method using a two-component developer (developer) containing toner and carrier as a developing device used in an image forming apparatus such as an electrophotographic method, a developer on a developer carrier before development is used. In order to regulate to a predetermined layer thickness, a layer thickness regulating member is arranged at a position via a developer carrier and a predetermined gap.
When such a layer thickness regulating member is used, a developer pool is formed in the vicinity of the upstream side of the layer thickness regulating member in the developer transport direction so that the entire amount of developer cannot pass through the gap of the layer thickness regulating member. Become. For this reason, the developer easily slips from the developer carrying member at this portion due to the influence of the accumulated developer, and the surface shape of the developer carrying member changes due to wear on the peripheral surface of the developer carrying member. . As a result, the amount of developer transported by the developer carrier changes, and the developer itself deteriorates due to slip, making it difficult to maintain a stable image over a long period of time. It was.

In order to reduce such developer accumulation, the developer transport amount is usually stabilized by adjusting the magnetic force of the developer carrier and the magnetic force (magnetic field) at the layer thickness regulation position. Measures are being taken.
On the other hand, due to the recent demand for higher image quality, proposals have been made to use a spherical carrier that can easily pass through the gap between the developer carrier and the layer thickness regulating member and can extend the life of the developer (patent). Reference 1).

Japanese Patent Laid-Open No. 11-24406 (Example) JP 2001-296735 A (Embodiments of the Invention, Table 1) JP 2000-231257 A (Embodiments of the Invention, Table 2) JP-A-10-90995 (Examples, Table 1)

  However, in general, a spherical carrier has a structure in which a magnetic material and a resin are dispersed. Therefore, compared to a conventional carrier using an irregular-shaped ferrite carrier, it is likely to have a low magnetic force. The developer used has a lower developer conveying force on the developer carrier than that using a ferrite carrier. Therefore, the developer accumulation on the upstream side of the layer thickness regulating member is more likely to occur, and the developer carrier is easily worn and the developer is likely to be deteriorated. As a result, there is a technical problem that the amount of developer transported by the developer carrier also changes with time, and the stability of image quality is impaired.

  The present invention is for solving such a technical problem, and pays attention to the peripheral surface of the developer carrying member that carries and conveys the two-component developer so as to obtain a stable peripheral surface over the long term. The present invention provides a developing device, an image forming apparatus using the same, a developer carrier, and a method for producing the same.

  As a technique paying attention to the peripheral surface of such a developer carrier, those described in Patent Documents 2 to 4 are known. Patent Document 2 describes a developer carrying body having a peripheral surface with a center line average roughness Ra of 1.0 to 2.0 μm and an uneven pitch of 3.8 μm or less and SRlr of 101% or less. Further, Patent Documents 3 and 4 describe a developer carrying member having peripheral surfaces in which large unevenness and small unevenness are provided, and large unevenness Ra and small unevenness SRlr are respectively defined.

  However, the developer carriers described in these patent documents are all made to solve the problems in using a one-component developer, and are not intended for a two-component developer. Patent Document 2 shows that the peripheral surface of the developer carrier is formed by chemical plating, chemical conversion treatment, or a resin film, while Patent Documents 3 and 4 show what is formed by a resin film. However, the main point is to prevent toner adhesion. Therefore, it does not focus on sliding between the developer and the developer carrier when using the two-component developer.

  As a result of intensive studies on the peripheral surface of an appropriate developer carrier for transporting a two-component developer (developer), the inventors of the present invention have found that a concave portion capable of transporting the developer is formed on the peripheral surface of the developer carrier. When the surface is roughened to form, sharp convex portions (surface convex portions) are easily formed around the concave portions, and the surface convex portions are rapidly worn by the accumulation of the developer. The inventor has found that the present invention has been obtained by obtaining the knowledge that the stability of the carrying amount over time is impaired.

  In other words, as shown in FIG. 1, the present invention has a developer carrier 2 disposed opposite to an image carrier 1, and the developer carrier 2 contains a two-component developer containing toner and carrier ( In the developing device for carrying and transporting the developer, the developer carrying body 2 forms a minute rough surface 3 capable of carrying the developer on the peripheral surface, and the surface convex portion 3a of the minute rough surface 3 is defined as a smooth surface 4. It is characterized by that. The smooth surface 4 is not particularly limited as long as it can remove the surface convex portion 3a of the minute rough surface 3 or conversely cover the surface convex portion 3a, and employs various polishing methods and various plating methods. Is possible.

  In such technical means, the developer carrier 2 may be any one that can carry and convey a two-component developer (developer) containing toner and carrier, and a representative embodiment is a rotatable nonmagnetic sleeve. The structure provided with the magnetic field generation | occurrence | production means fixedly arrange | positioned inside is mentioned. In addition, the developer carrier 2 and the image carrier 1 may be rotated in the same direction (with direction) at opposite positions or in the opposite direction (against direction).

  In the present invention, the minute rough surface 3 capable of carrying the developer is formed on the peripheral surface of the developer carrier 2, and the surface convex portion 3a of the minute rough surface 3 is the smooth surface 4. It becomes possible to ensure stable developer transportability over a long period of time. That is, when the micro rough surface 3 is formed, a sharp convex portion is easily formed around the concave portion of each micro rough surface 3, and when the developer is carried and transported as it is, the surface convex portion 3a is formed by the developer. As a result of the wear, the shape of the peripheral surface of the developer carrier 2 gradually changes. For this reason, the amount of developer transported by the developer carrier 2 changes over time, and the stability of image quality is impaired. On the other hand, in the present invention, since the surface convex portion 3a of the minute rough surface 3 is the smooth surface 4, even when the developer carrier 2 is worn due to the slip of the developer, the deformation amount can be suppressed to be small, and for a long time. Thus, a stable peripheral surface can be obtained, and the developer transport amount can be stabilized.

As a specific embodiment of the present invention, the developer carrier 2 has a peripheral surface with a center line average roughness Ra of 1.6 μm or more according to JIS B0601-1982, and an effective line length of the roughness curve. The thickness SRlr is preferably set to a surface shape of 103% or less.
Here, the center line average roughness Ra and the effective line length SRlr of the roughness curve will be described with reference to FIG. In the figure, assuming that the roughness curve f (x) within the range of the evaluation length l is as shown in the figure, the center line average roughness Ra is expressed by the average value of the shaded area in the figure ( (It corresponds to the equation (1) in the figure). On the other hand, the effective line length SRlr of the roughness curve cuts off each frequency component longer than 3.8 μm, and the total length of the obtained roughness curve f (x) is divided by the evaluation length (measurement section length) l. The value is expressed in% (corresponding to equation (2) in the figure).

In the present invention, Ra is set to 1.6 μm or more and SRlr is set to 103% or less, so that the edge portion 3a is formed into the smooth surface 4 while leaving the minute rough surface 3 on the peripheral surface of the developer carrier 2. It is possible to achieve a stable peripheral surface over a long period of time even when the developer slips.
Furthermore, in the present invention, the upper limit of Ra of the fine rough surface 3 is preferably 4 μm. If Ra is larger than this, the developer is more likely to slip on the developer carrier 2 and the peripheral surface is worn. Or the developer itself may be deteriorated, which may impair stabilization of the developer transport amount. Needless to say, when Ra is increased, SRlr itself tends to increase.

  The developer carrier used in the present invention preferably has a structure in which a magnetic material and a binder resin are dispersed and mixed. Such a dispersed and mixed carrier is a carrier having a high sphericity. The present invention is particularly suitable when a developer using such a carrier is used. In addition, what has a structure in which a magnetic substance and a binder resin are dispersed and mixed is one in which a magnetic substance and a resin are dispersed and mixed and pulverized and classified, one prepared by a polymerization method, or a porous magnetic substance impregnated with a resin. And the like. Further, by mixing and dispersing the magnetic material and the binder resin, the magnetization becomes smaller than that of the magnetic carrier alone.

The carrier is preferably prepared by a polymerization method and has a shape factor SF-2 of 115 or less. When the shape factor increases, the resistance to the developer in the gap of the layer thickness regulating member becomes too large, or the collision between the carriers increases, so that the deterioration of the toner is accelerated. The shape factor SF-2 is calculated by the following equation, where L is the peripheral length of the projected image of the carrier particles and S is the projected area of the carrier particle diameter.
SF-2 = (L ² / S) × {100 / (4π)}
From the viewpoint of achieving high image quality, the average particle size of the carrier is preferably 50 μm or less.

Furthermore, as a carrier, the strength of magnetization in a magnetic field of 10 ⁶ / 4π (A / m) (1000 Oe) is as low as 3.2π to 8.4π × 10 ⁻² Wb / m ² (80 to 210 emu / cm ³ ). It is preferable that the carrier has a magnetic force, and when such a low-magnetic carrier is used, the developer attracting agent tends to slip because the action of attracting the developer to the developer carrying member 2 is weakened. Since the peripheral surface 2 is resistant to changes in wear, a stable developer transport amount can be maintained over a long period of time. If the strength of the magnetization is larger than this, the wear of the peripheral surface of the developer carrier 2 by the developer increases. On the other hand, if the magnetization is smaller than this, the developer transportability by the developer carrier 2 is impaired. .

The present invention is not limited to the above-described developing device, and is also intended for an image forming apparatus using these developing devices. In this case, the image carrier 1 on which an electrostatic latent image is carried and the above-described developing device. And a developing device.
The present invention is also directed to the developer carrier 2, and in this case, a developer carrier that is disposed opposite to the image carrier 1 and is capable of carrying and transporting a two-component developer (developer) containing toner and carrier. 2 is characterized in that a minute rough surface 3 capable of carrying a developer is formed on a peripheral surface, and a surface convex portion 3a of the minute rough surface 3 is a smooth surface 4.

  Furthermore, the present invention is also directed to a manufacturing method for producing the developer carrier 2 described above. In this case, a two-component developer (development) that is disposed opposite to the image carrier 1 and includes a toner and a carrier. A developer carrying body 2 for producing a developer carrying body 2 capable of carrying and transporting a developer), and forming a rough surface 3 capable of carrying a developer on the circumferential surface of the developer carrying body 2 The present invention is characterized by performing a processing step and a smoothing processing step of smoothing the surface convex portion 3a of the minute rough surface 3 without damaging the minute rough surface 3 formed in the roughening step.

Here, the roughening treatment is not particularly limited as long as the peripheral surface of the developer carrier 2 can be roughened, and typical examples include blast treatment and chemical etching treatment. From the viewpoint of easily forming the surface 3, blasting (including liquid honing in which abrasive grains are mixed with a liquid and sprayed) is preferable.
Further, in the roughening process, if the fine rough surface 3 is once formed by the blasting process so that the center line average roughness Ra is slightly increased, and then the smoothing process is performed, the roughening process is performed during the smoothing process. It becomes possible to maintain a state in which the minute rough surface 3 formed by the crystallization treatment is not impaired.

  On the other hand, examples of the smoothing treatment include buffing with a buff, polishing with abrasive particles, electropolishing, and plating. Further, as the smoothing treatment, buff polishing is preferable from the viewpoint of smoothing the edge portion 3a without impairing the minute rough surface 3, and a nonmagnetic metal plating layer is formed from the viewpoint of covering the surface convex portion 3a. Is preferred. By applying a plating layer as a smoothing treatment, the surface property is maintained so as to reduce the amount of wear on the peripheral surface of the developer carrier 2, or conversely, a plating layer that is easily worn is formed and polished. However, the wear does not progress due to the base, and stable developer transportability is ensured. Specifically, nickel plating, chromium plating, etc. are mentioned as hard plating, and bright copper plating etc. are mentioned as soft plating.

According to the present invention, in the developing device using the developer carrier that carries and conveys the two-component developer, the developer carrier forms a minute rough surface on the circumferential surface on which the developer can be carried. Since the surface convex portion of the surface is a smooth surface, it is possible to realize a developing device capable of stabilizing the developer transport amount on the developer carrier over a long period of time.
Further, by using such a developing device, an image forming apparatus that can maintain stable image quality over a long period of time can be realized.
Furthermore, a minute rough surface capable of carrying the two-component developer is formed on the peripheral surface, and the surface convex portion of the minute rough surface is a smooth surface, so that stable developer transportability is ensured over a long period of time. A developer carrier can be realized.
Furthermore, a roughening treatment step for forming a fine rough surface capable of carrying the developer on the peripheral surface of the developer carrying member, and a fine roughening without damaging the fine rough surface formed in the roughening treatment step. Since the smoothing treatment step of smoothing the surface convex portion of the surface is performed, a production method for producing a developer carrier capable of stably carrying and transporting the two-component developer over a long period of time can be realized.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 3 shows an embodiment of an image forming apparatus including a developing device to which the present invention is applied. In the figure, reference numeral 21 denotes a photoconductor as an image carrier that rotates in the direction of the arrow and includes a photosensitive layer made of an organic photoconductive layer on the surface. The photoconductor 21 is charged by a charger 22 such as a charging roll. The electrostatic latent image is written by the exposure device 23 such as a laser writing device. The written electrostatic latent image is formed as a potential image based on the contrast with the high potential portion not exposed to light, because the surface potential of the exposed portion of the photoreceptor 21 is lowered.

  In addition, the developing device 30 disposed opposite to the photoreceptor 21 contains a two-component developer (developer) including a toner that is colored particles and a carrier that carries and transports the toner in a developing housing 31. The developer is carried on a developing roll 32 as a developer carrying member, and a developing bias from a bias power source (not shown) is applied to the developing roll 32 so that the developing roll 32 side has a high potential portion of the electrostatic latent image. The image portion of the electrostatic latent image on the photosensitive member 21 is developed with the charged toner in the developer.

  Further, a transfer device 24 is provided around the photoconductor 21, and this transfer device 24 is constituted by, for example, a transfer roll arranged in pressure contact with the photoconductor 21, and the toner on the photoconductor 21 by a bias power source (not shown). The toner image on the photoreceptor 21 is transferred to the recording material 26 by applying a transfer bias in the direction in which the image is attracted. The toner remaining on the photosensitive member 21 is removed by, for example, a doctor blade type cleaner 25.

  Furthermore, in the present embodiment, the recording material 26 onto which the toner image on the photoreceptor 21 has been transferred is conveyed to a fixing device 50, and the toner image on the recording material 26 is fixed by the fixing device 50. As the fixing device 50, for example, a heat roll method is adopted, which includes a heating roll 51 and a pressure roll 52, and a toner image is obtained by passing the recording material 26 between the heating roll 51 and the pressure roll 52. Is fixed to the recording material 26.

  As shown in FIG. 4, the developing device 30 in the present embodiment has a developing housing 31 that opens toward the photosensitive member 21, and a developing roll 32 is disposed facing the opening of the developing housing 31. A trimmer 33 as a layer thickness regulating member that regulates the layer thickness of the developer on the surface of the developing roll 32 is provided on the lower edge of the opening of the developing housing 31. The developing roll 32 in the present embodiment has a rotatable non-magnetic developing sleeve 32a having a peripheral surface whose surface shape is adjusted, and a plurality of magnetic poles (S1, N1, S2, in this example) inside thereof. S3, N2 magnetic poles) are fixedly provided with a magnet roll 32b. The S1 magnetic pole is disposed as a developing magnetic pole at a position facing the photosensitive member 21 at the position facing the photosensitive member 21, and the N1 magnetic pole as the conveying magnetic pole and the S2 and S3 magnetic poles (S3) as the repulsive magnetic poles on the downstream side in the developer conveying direction. The magnetic pole also serves as a pickup magnetic pole), and an N2 magnetic pole as a trimmer magnetic pole is arranged at a position facing the trimmer 33. The number and arrangement of the magnetic poles are not limited to this, and may be selected as appropriate.

  Further, behind the developing roll 32, two augers 34 (34a, 34b) capable of stirring and conveying the developer are provided with a partition wall 31a formed of a part of the developing housing 31 interposed therebetween. The auger on the roll 32 side is a supply auger 34a that mainly supplies developer to the developing roll 32, and the auger behind the partition wall 31a is an admixing auger 34b that mainly performs mixing and stirring of the developer.

Next, the developing sleeve 32a of the present embodiment will be described in detail.
The developing sleeve 32a of the present embodiment performs a blasting process by spraying a blasting material on the surface of a metal pipe such as an aluminum alloy or a stainless alloy so that the center line average roughness Ra becomes a predetermined value. Process. Thereafter, buffing is performed to form a peripheral surface having a center line average roughness Ra of 1.6 μm or more and an effective line length SRlr of the roughness curve of 103% or less.
The blasting material used for the blast treatment is not limited to glass-based, ceramic-based, metal-based, resin-based media, etc., but from the viewpoint of obtaining a desired surface roughness (uneven surface), use spherical particles of a predetermined particle size. Is preferred. Further, as buffing, it is possible to use abrasive particles such as alumina in combination.

FIG. 5A is a schematic cross-sectional view of the vicinity of the surface of the developing sleeve 32a in the present embodiment. When the developing sleeve 32a before processing (the peripheral surface is indicated by a two-dot chain line) is subjected to blasting, FIG. As shown in the left figure, a minute rough surface (indicated by a solid line in the figure) in which a plurality of concave portions overlap or are separated from each other is formed on the sleeve peripheral surface. At this time, the formed minute rough surface is in a state in which a convex portion having a sharp shape is formed around the concave portion. Thereafter, when a polishing process (buff polishing in this example) is performed, particularly the surface convex portions are polished, and the surface convex portions form a smooth curved portion as shown in the right figure. Such a developing sleeve 32a is used.
Further, as a developer carrier used in the present embodiment, a so-called spherical carrier having a shape factor SF-2 of 110 produced by a polymerization method was used. Further, the magnetization strength of the carrier at this time was 4π × 10 ⁻² Wb / m ² (100 emu / cm ³ ).

Next, the operation of the image forming apparatus in the present embodiment will be described with a focus on the developing device 30.
In FIG. 4, the developer charged with a predetermined charge by the admix auger 34b and the supply auger 34a is on the developing roll 32 (specifically on the developing sleeve 32a) by the action of the S3 magnetic pole of the pickup magnetic pole of the developing roll 32. Led to. The developer guided onto the developing sleeve 32a is conveyed on the developing sleeve 32a by the rotation of the developing sleeve 32a and the magnetic field between the S3 magnetic pole and the N2 magnetic pole of the trimmer magnetic pole.
At the portion of the trimmer 33, the developer that has been sufficiently raised by the action of the N2 magnetic pole is regulated to a predetermined layer thickness by a trimmer gap that is a gap between the trimmer 33 and the developing sleeve 32a, and the regulated layer thickness. The developer is conveyed to a developing area which is an area where the photoconductor 21 and the developing roll 32 are opposed to each other, and the toner in the developer develops an electrostatic latent image on the photoconductor 21 in this developing area. Become.

  The developed developer is transported as it is to the N1 magnetic pole and S2 magnetic pole as the developing sleeve 32a rotates, and then picked off from the developing sleeve 32a by the action of the repulsive magnetic field composed of the S2 magnetic pole and the S3 magnetic pole. The picked-off developer is returned to the auger 34, and after agitation is repeated by the auger 34, the developer is again used for development.

In the operation of the developing device 30 as described above, the developer regulated by the trimmer gap tends to be collected in the vicinity of the upstream side of the trimmer 33.
That is, since the developer carrier is spherical and has a low magnetic force, the developing sleeve 32a has a weak force (developer holding force) for holding the developer toward the developing sleeve 32a, particularly at this portion. As a result, the developer conveying force is reduced, and a further reservoir is formed. As a result, the developer is transported at a speed lower than the peripheral speed of the developing sleeve 32a, so that the developer slips on the surface of the developing sleeve 32a.

  Normally, when the developer slips on the surface of the developing sleeve 32a, wear of the sleeve surface is promoted and the roughness of the surface decreases, resulting in a decrease in the amount of developer transported by the developing sleeve 32a. It becomes like this. This is especially true on the sleeve surface where only the blasting process is performed, as shown in the left figure of FIG. 5 (a), sharp protrusions are formed around the recesses (surface side) formed by the blasting process. Then, the surface protrusion is rapidly worn by the developer slip. For this reason, the developer conveyance amount is rapidly reduced. Then, after the surface convex portion is worn, the overall wear of the sleeve surface gradually proceeds, and the change in the developer conveyance amount becomes gradual. Therefore, the initial fluctuation until the surface convex part is worn out is particularly large. At this time, the developer conveyance amount is greatly reduced, and an image defect such as a reduction in image density occurs. At this time, the SRlr on the sleeve surface also tends to decrease rapidly due to wear.

On the other hand, the developing sleeve 32a of the present embodiment is further subjected to buffing after the surface is blasted, so that the surface convex portion generated by the blasting is from the beginning as shown in the right figure of FIG. Since it is removed, the wear of the sleeve surface due to the slip of the developer can be suppressed, and the change in the developer conveyance amount can be suppressed to a small level.
Furthermore, in the present embodiment, Ra on the sleeve surface by blasting is set to 1.6 μm or more and SRlr is set to 103% or less, so that the concave portion of the sleeve surface can be shallow and the concave portions are not arranged too densely. Thus, wear of the sleeve surface due to developer slip can be reduced, and a stable developer conveyance amount can be maintained over a long period of time. Therefore, stable image formation can be performed over a long period of time.

In the present embodiment, a method of performing buffing as a polishing process after performing a blasting process on the surface of the developing sleeve 32a has been described. If Ra and SRlr can be set to predetermined values, polishing with abrasive particles, Other polishing methods such as electrolytic polishing may be used.
Further, in the present embodiment, the method of performing the polishing process as the smoothing process after performing the blasting process as the roughening process is shown, but the plating process may be performed instead of the polishing process as the smoothing process. .

FIG. 5B shows a cross section of the developing sleeve 32a when bright copper plating is performed as an example of the plating process. The left figure shows the shape after the blasting process, and the right figure shows the plating process. The state that has been performed is shown.
In this case, a blast process is performed so that the surface of the developing sleeve 32a has a predetermined Ra, and a bright copper plating is performed after an appropriate base treatment. Then, a plating film is formed so as to cover the edge portion generated by the blasting process, and a surface shape having a value smaller than the Ra and SRlr values after the blasting process is formed. In particular, when such a soft plating film is used as the plating film, the wear resistance of the film itself is lower than when a hard plating film is used, but the initial change in transportability is smooth due to the plating film. On the other hand, the change in transportability over time can be maintained with the roughness of the substrate that comes out after the plating film is shaved. Further, by using such an inexpensive plating film, it is possible to expand the cost performance options in relation to the durability and cost of the component as the developing sleeve 32a.

  Further, the plating film is not limited to the bright copper plating described above, and for example, a bright nickel plating film may be formed as the hard plating film. If a hard film is used as the plating film, it is possible to smoothen the surface and reduce the amount of wear caused by the slip of the developer, so that a stable surface can be maintained over a long period of time. become. Furthermore, when more durability is required, a plating film having a higher hardness such as a chromium plating film may be applied to the surface of the bright nickel film. In addition, since the film | membrane used for these requires a nonmagnetic characteristic, it cannot be overemphasized that various additives etc. are adjusted.

As described above, in the present embodiment, the surface of the developing sleeve 32a is subjected to a blasting process as a roughening process and then subjected to a polishing process or a plating process as a smoothing process to obtain a centerline average roughness Ra of the sleeve surface. Since the effective line length SRlr of the roughness curve is set to a predetermined value, a stable developer conveyance amount is maintained over a long period of time despite the use of a spherical carrier as the developer carrier. Will be able to.
Although the image forming apparatus of the present embodiment is shown as a single color, it goes without saying that it can be applied to, for example, a full color image forming apparatus using a plurality of such developing devices 30.

Example 1
This example evaluated and confirmed how the developer amount MOS (Mass on Sleeve) on the developing sleeve changes when the developer of the polymerization carrier is used in two types of developing sleeves having different surface shapes. It is. For comparison, a conventional combination (combination of conventional ferrite carrier developer and conventional developing sleeve) was also evaluated.
The developing sleeve used was adjusted so as to be Ra 1.6 μm or more and SRlr 103% or less by performing buffing after blasting as in the present invention. Further, a comparative example (conventional developing sleeve) was subjected to blasting (Ra 5 μm, SRlr 108%).
In the test, the output of a normal image area ratio of about 5% was output, and the change in MOS was measured by measuring the amount of developer on the developing sleeve as appropriate.

As a result, as shown in FIG. 6, in the case of using a polymerized carrier (polymerized CA), it has been found that the state of change of MOS varies greatly depending on the developing sleeve. As a result, it was found that the MOS voltage suddenly decreased and became saturated at about 200,000 sheets. On the other hand, it was confirmed that the development sleeve (this sleeve) of the present invention did not change greatly even when 300,000 sheets were output.
On the other hand, it has been found that the combination of the conventional ferrite carrier developer (conventional developer) and the conventional sleeve gradually reduces the MOS.
From this, it can be seen that by using the polymerized carrier, the surface wear of the developing sleeve becomes larger than when a conventional developer is used, and the developer slips violently on the developing sleeve. In addition, assuming that about 80% of the initial change in MOS is considered to be a pass line, when using a polymerized carrier, the conventional sleeve can output only about 50,000 sheets, but this sleeve has a problem even if 300,000 sheets are output. It was confirmed that this was not the case, and the effectiveness of this case was confirmed again. In addition, in the conventional combination, it is about 230,000 sheets, and it became clear that it was more stable for a long time than this.

Example 2
In this embodiment, attention is paid to Ra and SRlr of the developing sleeve, and the maintenance of the developing sleeve is evaluated and confirmed when output is repeated using a polymer carrier as a developer.
As for maintainability, the print output is repeated as in the first embodiment, and the MOS is measured as appropriate until the output of 300,000 sheets is performed, and it is determined whether the change from the initial level of the MOS is less than 80%. Was NG.
The result was as shown in FIG. Here, the ◯ mark indicates an OK level, the X mark indicates an NG level, and the ● mark indicates an actual measured value of Ra and SRlr of only a blasting process performed on a developing sleeve. It is a thing.

According to this result, it was found that if the Ra on the surface of the developing sleeve is 1.6 μm or more and SRlr is 103% or less, a stable MOS can be maintained, and the effectiveness of the present case has been confirmed. Moreover, when Ra exceeded 4 micrometers, it was also confirmed that possibility of becoming NG is high.
Furthermore, the present inventors have repeatedly studied in detail about the developer to be used, and confirmed that the same result as described above can be obtained if the shape factor SF-2 of the carrier is 115 or less. Further, it was confirmed that the same effect can be obtained if the magnetization intensity of the carrier is 3.2π to 8.4π × 10 ⁻² Wb / m ² (80 to 210 emu / cm ³ ).

It is explanatory drawing which shows the outline | summary of the image development apparatus concerning this invention. It is explanatory drawing which shows the effective line length SRlr of centerline average roughness Ra and a roughness curve. 1 is an explanatory diagram showing an embodiment of an image forming apparatus to which the present invention is applied. It is explanatory drawing which shows the developing device of embodiment. It is a cross-sectional schematic diagram in the vicinity of the surface of the developing sleeve of the embodiment, (a) is buffed as a smoothing process, (b) is a plated film. 3 is a graph showing the results of Example 1. 10 is a graph showing the results of Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Developer carrier, 3 ... Micro rough surface, 3a ... Surface convex part, 4 ... Smooth surface

Claims (10)

In a developing device having a developer carrying member disposed opposite to an image carrying member and carrying and transporting a two-component developer containing toner and carrier on the developer carrying member,
The developer carrying member is characterized in that a minute rough surface capable of carrying a developer is formed on a peripheral surface, and a surface convex portion of the minute rough surface is a smooth surface. The developing device according to claim 1,
The developer carrying member has a peripheral shape whose surface has a center line average roughness Ra of 1.6 μm or more according to JIS B0601-1982 and an effective line length SRlr of the roughness curve of 103% or less. A developing device. The developing device according to claim 2, wherein
The developing device according to claim 1, wherein Ra of the rough surface is set to 4 μm or less. The developing device according to claim 1,
2. A developing device according to claim 1, wherein the developer carrier has a structure in which a magnetic material and a binder resin are dispersed and mixed. The developing device according to claim 4.
A developing device, wherein the carrier is produced by a polymerization method and has a shape factor SF-2 of 115 or less. The developing device according to claim 5, wherein
The carrier has a low magnetic force with a magnetization intensity of 3.2π to 8.4π × 10 ⁻² Wb / m ² (80 to 210 emu / cm ³ ) in a magnetic field of 10 ⁶ / 4π (A / m) (1000 Oe). A developing device characterized by the above. An image carrier on which an electrostatic latent image is carried;
An image forming apparatus comprising: the developing device according to claim 1. A developer carrier that is disposed opposite to an image carrier and is capable of carrying and transporting a two-component developer containing toner and carrier,
A developer carrying member characterized in that a minute rough surface capable of carrying a developer is formed on a peripheral surface, and a surface convex portion of the minute rough surface is a smooth surface. A method for producing a developer carrying member for producing a developer carrying member that is disposed opposite to an image carrying member and capable of carrying and transporting a two-component developer containing toner and carrier,
A roughening treatment step for forming a fine rough surface capable of carrying the developer on the circumferential surface of the developer carrying member;
A method for producing a developer bearing member, comprising performing a smoothing treatment step of smoothing a surface convex portion of a fine rough surface without damaging the fine rough surface formed in the roughening treatment step. In the method for producing a developer carrier according to claim 9,
The method for producing a developer carrying member, wherein the smoothing treatment forms a non-magnetic metal plating layer.

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