JP2001290348A - Image forming device and electrophotographic photoreceptor used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of improving irregular image density (irregular color in the case of a color image) caused by irregular coating of a photoresensitive layer even when the resolution of the image forming device gets high and restraining the irregular image density and the irregular color to be little even when the ratio of the peripheral length of an electrophotographic photoreceptor to that of an intermediate transfer body becomes a non-integer due to miniaturization in an electrophotographic device capable of varying the quantity of laser beam in two or more stages in image exposure by the laser beam. SOLUTION: In the image forming device constituted so that a half tone is reproduced by forming an electrostatic latent image on the electrophotographic photoreceptor, visualizing the electrostatic latent image with toner and then transferring it, the photoreceptor is constituted of an under coating layer, a charge generating layer and a charge transporting layer, and the charge generating layer incorporates silicone oil. Then, potential irregularity ΔVL in the peripheral direction of the photoreceptor by the image exposure and the resolution Rs of the image exposure by the laser beam satisfy a following expression (1). The expression (1) is ΔVL<=12,000/Rs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light image exposure image forming apparatus for changing the amount of light in two or more steps, and an electrophotographic photosensitive member used in the image forming apparatus.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 9-190000 discloses that the interface between the charge generation layer and the charge transport layer is unevenly and finely roughened by means of etching, sanding, or the like, thereby obtaining pitch unevenness due to uneven rotation of the photosensitive drum. However, it is described that banding and the like can be reduced, but when etching or the like is performed, a coating film defect may occur in the photosensitive layer due to the inclusion of foreign matter. Further, the degree of non-uniformity is described as about the resolution characteristic of the printer (about the sub-scanning pitch, for example, 600 dpi). However, as the resolution increases, the effect on the rotation unevenness of the photosensitive drum is lost. JP-A-5-1652
Japanese Patent Application Laid-Open No. 71 discloses that uneven rotation of the photoconductor is prevented to prevent density unevenness from occurring in the image. However, it is necessary to prevent image density unevenness caused by uneven coating of the photosensitive layer. Can not.

Japanese Patent Application Laid-Open No. 55-140849 discloses that a photoconductive layer contains a silicone leveling agent to improve the smoothness of the coated surface of the photoconductive layer.
There is only a description of an example of a single-layer photoconductive layer using an inorganic pigment such as dS, but what happens when a silicone leveling agent is contained in the charge generation layer of the laminated electrophotographic photoreceptor is described. Absent.

Japanese Patent Application Laid-Open No. Hei 3-113457 describes that by containing a volatile leveling agent in an electrophotographic photoreceptor coating material, good coating smoothness and photoreceptor characteristics can be obtained. There is a statement that the layer and the charge transport layer may contain a volatile leveling agent, but as a result there is no specific disclosure about the smoothness of the coating film.

Japanese Patent Application Laid-Open No. Sho 59-208556 discloses that a conductive layer contains a leveling agent and has good coating smoothness.
Although it is described that the photoconductor characteristics are obtained, the conductive layer contains a leveling agent to obtain good coating smoothness and photoconductor characteristics, and the charge generation layer contains a silicone leveling agent. No specific examples are described.

Japanese Patent Application Laid-Open No. 9-325621 describes that the surface roughness of an intermediate transfer member is specified to prevent image unevenness and image shrinkage during toner transfer from an electrophotographic photosensitive member to an intermediate transfer member. However, in a full-color image forming apparatus using an intermediate transfer member, partial color unevenness occurs unless three color toners are formed uniformly over the entire image. In order to reduce this color unevenness, in an image forming apparatus such as a full-color copy, the sensitivity unevenness in the circumferential direction of the electrophotographic photoreceptor is usually set at a timing so that each color of the separated image is formed at the same place on the electrophotographic photoreceptor. The effects of reducing. For this reason, the ratio φc / φd of the peripheral length φd of the electrophotographic photosensitive member to the peripheral length φc of the intermediate transfer body is usually set to be an integral multiple, and when the image forming apparatus is downsized,
There is a problem that the circumference of the electrophotographic photosensitive member cannot be reduced from the required image size.

On the other hand, when the resolution of an image forming apparatus using a laser beam increases, fine coating unevenness tends to appear in an image. In general, image processing makes these defects less likely to appear on an image, but the processing software becomes complicated, causing problems such as a reduction in printing speed.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus in which image exposure with laser light can vary the amount of laser light in two or more steps, even if the resolution of the image forming apparatus increases. An object of the present invention is to provide an electrophotographic apparatus capable of improving image density unevenness (color unevenness in the case of a color image) caused by unevenness in coating of an image forming apparatus. Perimeter φd of electrophotographic photosensitive member used in full-color image forming apparatus
An object of the present invention is to provide an image forming apparatus with less image density unevenness and color unevenness even when the ratio φc / φd of the image transfer length to the intermediate transfer member φc is a non-integer.

[0009]

The object of the present invention is to provide an electrostatic latent image formed on an electrophotographic photosensitive member by charging and exposing an image with a laser beam, and forming the electrostatic latent image by toner. In an image forming apparatus configured to reproduce a halftone by transferring after visualization, the electrophotographic photoreceptor includes an undercoat layer, a charge generation layer, and a charge transport layer, and the charge generation layer is formed of silicone oil. And potential unevenness ΔV in the circumferential direction of the electrophotographic photosensitive member due to image exposure
L, the resolution Rs of the image exposure by the laser beam is expressed by the following equation (1).
An image forming apparatus characterized by satisfying the following.

ΔVL ≦ 12000 / Rs Expressions (1) and (2) “After developing toner of at least three colors three times or more, the development of each color is superimposed on the intermediate transfer member. (3) An image forming apparatus configured to transfer a toner image onto an intermediate transfer member, and an electrophotographic apparatus. The image forming apparatus according to the above (1) or (2), wherein the ratio φc / φd of the circumference φd of the photoconductor and the circumference φc of the intermediate transfer body is a non-integer, (4) The image forming apparatus according to any one of (1) to (3), wherein the image exposure with the laser light is performed by changing the amount of laser light in two or more steps. (5) "Being a reversal developing type electrophotographic apparatus using one-component non-magnetic toner" Is achieved by the features first (1) The image forming apparatus according to any one of claim to the item (4) ".

The above object is also achieved by (6) the present invention, wherein the electrophotographic photoreceptor is formed by dip coating a charge generating layer coating solution comprising a silicone oil, an organic pigment, a binder resin and an organic solvent. And (7) "viscosity of the silicone oil", wherein the silicone oil content in the coating solution for the charge generation layer is 1.0 to 10 wt% of the binder resin. Of the electrophotographic photoreceptor according to the above (6), which is 50 to 200 cp.

That is, an electrophotographic photosensitive member used in an image forming apparatus comprises an undercoat layer, a charge generating layer, and a charge transporting layer, wherein the charge generating layer contains silicone oil, and is formed by image exposure. Potential unevenness ΔV in the circumferential direction of
L, when the resolution Rs of the image exposure by the laser beam satisfies the above formula (1), even when the resolution is increased, it is possible to make it difficult for the fine coating unevenness to appear in the image by inexpensive means. Resolution R of image exposure by laser light
As means for varying s, it is possible to use means such as laser power modulation, laser spot diameter change, and pulse width (PWM) modulation.

After developing at least three or more colors of toner for each color, the development of each color is superimposed at the same position on the intermediate transfer member by a position sensor provided on the intermediate transfer member. With this configuration, an image forming apparatus without color shift can be provided.

The image forming apparatus of the present invention is an image forming apparatus configured to transfer a toner image onto an intermediate transfer member, and has a circumference φd of an electrophotographic photosensitive member and a circumference φc of an intermediate transfer member. By making the ratio φc / φd to a non-integer,
Even if the image forming apparatus is downsized, an image forming apparatus with less image density unevenness and color unevenness can be provided.

Further, since the image forming apparatus of the present invention is an electrophotographic apparatus of a reversal development system using a one-component non-magnetic toner, the image forming apparatus satisfies halftone, line reproducibility, and solid density. Can be provided.

Further, since the image forming apparatus of the present invention performs image exposure by changing the amount of laser light in two or more steps, an image forming apparatus excellent in reproducibility of halftones such as halftones can be provided. Can be provided.

Further, the charge generation layer of the electrophotographic photoreceptor of the present invention is formed by dip coating, and the content of silicone oil in the charge generation layer coating solution is 1.0% with respect to the resin in the charge generation layer coating solution. By setting the content to 10 wt%, a charge generation layer with less coating unevenness can be formed, and an electrophotographic photosensitive member with less image density unevenness and color unevenness can be provided.

The viscosity of the silicone oil in the coating solution for the charge generation layer of the electrophotographic photoreceptor of the present invention is adjusted to 50 to 200 c.
By setting p, a charge generation layer with less coating unevenness can be formed, and an electrophotographic photosensitive member with less image density unevenness and color unevenness can be provided.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 shows an image forming apparatus 1 used in the present invention.
This is an example. (1) is a photoconductor which is driven to rotate in the direction of arrow A, and the surface thereof is uniformly charged to a predetermined polarity by a charging device (2). The scanning optical device (3) forms an electrostatic latent image on the surface of the photoconductor charged with a laser beam (3A) corresponding to writing information (for each color) from a laser light source (not shown). This latent image is
The image is developed and visualized by a black toner developing unit, a yellow developing unit, a magenta developing unit, and a cyan developing unit provided in the multicolor developing device (4). In the multicolor developing device (4), a desired developing unit is rotated to a predetermined position by a driving device (not shown), and comes into contact with or separates from the photoconductor.

(7) is a belt-shaped intermediate transfer member rotatably supported by rollers (8), (9) and (10), and rotates in the direction of arrow B. The toner image on the photoreceptor is received where it comes into contact with the photoreceptor (1), which is due to the action of the bias means (11). In forming a full-color image, toner images of each color of black, yellow, magenta, and cyan are superimposed on the intermediate transfer body (7), and are collectively transferred to paper. The transfer is performed by a transfer roller (12).
The paper (13A) is stored in a paper feeder (paper feed cassette) (13).
The sheet is fed by the rotation of the sheet feeding roller (14), and is conveyed through the conveying roller pair (15). Timing is set by the pair of registration rollers (16), and the toner image on the intermediate transfer body (7) is transferred to a predetermined position on the sheet. Thereafter, the sheet passes through a fixing device (17), and the toner image is fixed.

When the toner is transferred from the photosensitive member (1) to the intermediate transfer member (7), the toner remaining on the photosensitive member (1) is scraped off by a cleaning means (blade) (5). On the other hand, when the toner is transferred from the intermediate transfer member (7) to the sheet, the toner remaining on the intermediate transfer member (7) is scraped off by the cleaning blade (18). The photoreceptor cleaning means (blade) (5) always performs a cleaning operation, but the cleaning blade (18) of the intermediate transfer body contacts the intermediate transfer body after transferring the toner image onto the paper, and scrapes the remaining toner. It is controlled to take. After the cleaning process, the light from the neutralization lamp (6) makes the residual potential on the photoconductor normal, and the process proceeds to the next image forming process.

FIG. 2 is a diagram schematically showing the scanning optical device (3) of FIG. After passing through a cylinder lens (23) from a laser light source (22) and passing through optical components such as a polygon mirror (24), an fθ lens (25), and a mirror (26) rotated by a motor (not shown), The laser beam (22D) corresponding to the write information reaches the photoconductor (1) in FIG. As a means for changing the resolution Rs of the image exposure by the laser beam in two or more steps, a method of changing the resolution Rs by changing the rotation speed of the polygon mirror (24), a method of changing the process speed, a laser light source (22) Power modulation by varying the drive current of P
A method of varying the dot size by the WM method (described in JP-A-62-39972), a change in the laser spot diameter by adding a diaphragm mechanism to the cylinder lens (23) of the scanning optical device (3), etc. There is. As the device, a method of varying the drive current of the laser light source (22) by power modulation and a method of varying the dot size by the PWM method are preferable.

In the formation of a full-color image, the method of superimposing color toner images of black, yellow, magenta, and cyan on the intermediate transfer member (7) is different from the tandem method of performing color superposition on paper. Excellent color shift, image dimensional accuracy, etc. The ratio φc / φd of the circumference φd of the photoconductor (1) to the circumference φc of the intermediate transfer body (7) is a non-integer.

In the multicolor developing device (4) of the present invention, a reversal development system using a one-component non-magnetic toner is preferable in terms of image gradation, density uniformity, line reproducibility, and solid portion density.
In addition, the potential unevenness ΔVL in the circumferential direction of the photoconductor (1) can be measured by attaching an electrometer to the developing sleeve position of the multicolor developing device (4).
It is determined from the maximum and minimum of the circumferential potential formed by exposing the scanning optical device (3) of FIG. 1 to laser light (3A) corresponding to the write information corresponding to the halftone image.

FIG. 3 is a sectional view of the electrophotographic photosensitive member used in the present invention. As the support (31), aluminum, nickel, nickel-cobalt alloy, stainless steel or the like is used. I. , I .; I. , Extruded, drawn out, etc., then piped, then cut, super-finished, polished, etc.
A seamless belt made of nickel, iron, beryllium-copper alloy, or the like can be used.

The undercoat layer (32) is made of a thermoplastic resin such as polyamide, polyvinyl alcohol, casein or ethyl cellulose, a thermosetting resin such as phenol, melamine, alkyd, or unsaturated polyester, or a titanium oxide or an oxidized resin. A dispersion of pigments such as zinc and carbon is used, and the film thickness is 0.1 to 12 μm.

The charge generation layer (33) is composed of an organic pigment such as a silicone oil, an azo pigment, a phthalocyanine pigment, a quinacridone pigment or a perylene pigment represented by the following formula and Table 1.
Binder resins such as polyvinyl butyral, polyamide, polyester, epoxy resin, silicone resin, phenoxy resin, polyvinyl formal, polystyrene, polycarbonate, and polyacrylamide can be used as cyclohexanone, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, isobutanol, 1,1,2,2 It is formed by dip-coating a coating solution dispersed in an organic solvent such as tetrachloroethane, ethyl cellosolve, 1,1, trichloroethane or a mixed solvent thereof on a support. The thickness of the charge generation layer (33) is suitably about 0.01 to 5 μm, and preferably 0.1 to 2 μm.

The ratio of the pigment to the binder resin in the coating solution for the charge generation layer is preferably from 1/10 to 10/1, more preferably from 1/3 to 3/1. In this, additives such as a sensitizer and an antioxidant may be added.

[0028]

Embedded image (Wherein, R _{1 to} R ₈ are an alkyl group such as a methyl group or an ethyl group, an aryl group such as phenyl, or a methoxy group;
Shows an alkoxy group such as an ethoxy group, these groups may be substituted with other substituents or halogen atoms,
m represents an integer. Representative silicone oils include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, alkyl-modified silicone oil, alkylallyl-modified silicone oil, fluorine-modified silicone oil, amino-modified silicone oil, and epoxy-modified silicone oil. Methacryloxy-modified silicone oil, alcohol-modified silicone oil, polyether-modified silicone oil, and the like. )

[0029]

[Table 1]

The viscosity of the silicone oil is 20 c
s to 1000 cs is preferred, more preferably 50 cs
s to 200 cs. Volatile silicone oil (molecular weight: 1000 or less) of about several cs has no effect on the improvement of the shading unevenness even if the added amount is increased, and is suppressed to the shading unevenness when the added amount is further increased. Before the effect is seen, another coating defect such as repelling appears. On the other hand, 1000c
Silicone oil having a viscosity of s or more has an effect on shading unevenness, but causes coating film defects such as repelling. If the viscosity or amount of silicone oil is not suitable,
It has an adverse effect on coatings and electrostatic properties. It is necessary that the added silicone oil be completely dissolved in the solvent of the dispersion liquid, and the effect is sufficient even if the added amount is very small.

The content of the silicone oil is preferably from 0.5 to 40% by weight, more preferably from 1.0 to 10% by weight, based on the binder resin contained in the dispersion. When the addition amount is 0.5% by weight or less, almost no effect on light and shade unevenness is obtained, and when it is 40% by weight or more, there is an effect on light and shade unevenness, but another coating defect such as repelling tends to occur. Further, when the content is 40% by weight or more, adverse effects on the residual potential and the like are also observed in the electrostatic characteristics. Further, the adhesive strength at the interface with the charge transport layer also decreases.
These silicone oils may be added before dispersion or after the dispersion is completed.

The charge transport layer (34) comprises a charge transport material such as a hydrazone compound, a butadiene compound, a stilbene compound, a carbazole compound, a triarylamine compound, a benzidine compound, a polycarbonate resin, a polymethacrylate, a polystyrene resin, a polyester resin. Binder resins such as polysulfone resin, phenoxy resin, urethane resin, and phenol resin are mixed with tetrahydrofuran, dioxane, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane,
It is formed by dissolving in an organic solvent such as 1,2-trichloroethane, chlorobenzene, toluene or the like and applying it on the charge generation layer (33). If necessary, a plasticizer, a leveling agent and an antioxidant may be added.

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer (34). As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is suitably about 5 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethylsilicone oil and methylphenylsilicone oil, and polymers or oligomers having perfluoroalkyl side chains are used. About 1% by weight is appropriate. The leveling agent added here can be shared with the leveling agent contained in the charge generation layer in the present invention, and it is more preferable to do so.

In the electrophotographic photosensitive member of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer.
Materials used for the protective layer include ABS resin, ACS
Resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene Examples include resins such as terephthalate, polyimide, acrylic resin, polymethylbenzene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. In the protective layer,
In addition, for the purpose of improving abrasion resistance, adding a fluorine resin such as polytetrafluoroethylene, a silicone resin, or a dispersion of an inorganic material such as titanium oxide, tin oxide, potassium titanate, or the like to these resins. Can be. As a method for forming the protective layer, a normal coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm.

In the present invention, an intermediate layer can be provided between the photosensitive layer and the protective layer. The intermediate layer generally uses a binder resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

Table 2 shows specific examples of the charge generation material.

[0037]

[Table 2]

Table 3 shows specific examples of the charge transport material.

[0039]

[Table 3]

[0040]

The present invention will be described in more detail with reference to the following examples. In each example, "parts" means parts by weight. Example 1 An undercoat layer having a thickness of about 3 μm made of titanium oxide and a thermosetting resin was formed on an aluminum drum-shaped support having a diameter of 80 mm and a length of 352 mm.

Subsequently, 2 parts of the charge generating substance of (Chemical Formula 21), 1 part of the charge generating substance of (Chemical Formula 22), 1 part of polyvinyl butyral resin (Eslec BLS; manufactured by Sekisui Chemical), and cyclohexanone (Kanto Chemical) shown in Table 2 The mixture consisting of 80 parts was placed in a ball mill pot, and ball-milled for 48 hours using a φ10 mm SUS ball, and then 51.3 parts of cyclohexanone and methyl ethyl ketone 13 were added.
1.3 parts and 0.015 parts of the silicone oil (Chemical Formula 14) shown in Table 1 were added to prepare a charge generation layer coating solution. This coating solution was placed in a coating tank having an inner diameter of 124 mm, applied onto the undercoat layer by dip coating, and then dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.12 μm. Subsequently, a charge transport layer coating solution having the following composition was prepared, applied on the charge generation layer, and dried at 110 ° C. for 20 minutes to form a charge transport layer having a thickness of 25 μm to prepare an electrophotographic photoreceptor.

8 parts of a charge-transporting substance (manufactured by Ricoh) in Table 3 (Chemical formula 44) Polycarbonate resin (C-1400; manufactured by Teijin Chemicals) 10 parts Dichloromethane (manufactured by Kanto Chemical) 88 parts Silicone oil (KF-50; manufactured by Shin-Etsu Chemical) Viscosity 100 cp) 0.0002 parts

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the silicone oil of the charge generating layer coating liquid was omitted.

The electrophotographic photosensitive members of Example 1 and Comparative Example 1 prepared as described above are attached to the image forming apparatus shown in FIG. 1, and the scanning optical device (3) corresponds to a black halftone image in a single color mode. Image exposure, multicolor developing device (4)
A black halftone image was printed by the black toner developing unit provided in the above, and the density difference in the image was measured with a Macbeth densitometer. Similarly, image exposure corresponding to a gray halftone image is performed from the scanning optical device (3) in the three-color mode, and color unevenness of the gray halftone image developed and output by the yellow developing unit, the magenta developing unit, and the cyan developing unit is performed. Was visually evaluated. The potential unevenness ΔVL in the circumferential direction of the photoreceptor was measured by removing the black toner developing unit of the multicolor developing device (4), attaching a surface voltmeter to the position, and measuring the potential unevenness in the circumferential direction. The resolution Rs at the time of image exposure of the scanning optical device (3) is 300 dpi, 400 dpi using both laser power modulation and PWM.
i and 600 dpi were evaluated. Since the circumference of the intermediate transfer belt (7) was 450 mm, the ratio φc / φd of the circumference φd of the electrophotographic photosensitive member (1) to the circumference φc of the intermediate transfer belt (7) was 1.79. Table 4 shows the results.

Evaluation criteria A: No color unevenness O: Almost no color unevenness Δ: A little color unevenness X: Color unevenness

[0046]

[Table 4]

Example 2 In Example 1, the charge generating substance was changed to 3 parts of the electrifying substance of (Chemical Formula 22) shown in Table 2 and the silicone oil was changed to 0.02 parts of (Chemical Formula 15) of Table 1 Except for the above, an electrophotographic photosensitive member was prepared in exactly the same manner as in Example 1.

[Comparative Example 2] In Example 2, the silicone oil of the coating solution for the charge generation layer was changed to 0.0
An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 2 except that one part was changed.

Comparative Example 3 An electrophotographic photosensitive member was prepared in exactly the same manner as in Example 2 except that the silicone oil used in the coating solution for the charge generation layer was changed to 0.5 part. Repelling occurred in the generated layer coating film.

The electrophotographic photosensitive member prepared as described above is
Attached to the image forming apparatus shown in FIG. 1 in the same manner as in Example 1 and Comparative Example 1, an image exposure corresponding to a black halftone image was performed from the scanning optical device (3) in a single color mode, and the multicolor developing device (4) was used. A black halftone image was printed by the provided black toner developing unit, and the density difference in the image was measured by a Macbeth densitometer. Similarly, image exposure corresponding to a gray halftone image is performed from the scanning optical device (3) in the three-color mode, and color unevenness of the gray halftone image developed and output by the yellow developing unit, the magenta developing unit, and the cyan developing unit is performed. Was visually evaluated. Further, the potential unevenness ΔVL in the circumferential direction of the photoreceptor is determined by a multicolor developing device (4).
The black toner developing unit was removed, and a surface voltmeter was attached to that position to measure the potential unevenness in the circumferential direction. In addition,
The resolution Rs at the time of image exposure of the scanning optical device (3) is 400 dpi, 6 using both laser power modulation and PWM.
Evaluation was made at three types of 00 dpi and 800 dpi. Since the circumference of the intermediate transfer belt (7) was 450 mm, the ratio φc / φd of the circumference φd of the electrophotographic photosensitive member (1) to the circumference φc of the intermediate transfer belt (7) was 1.79. Table 5 shows the results. (However, in Comparative Example 3, the image and the potential measurement were not evaluated because the charge generation layer coating film was repelled.)

[0051]

[Table 5]

Example 3 and Comparative Example 4 In the image forming apparatus shown in FIG. 1, the circumference φc of the intermediate transfer belt (7)
Is changed to 502.7 mm, and the ratio φc / perimeter of the circumference φd of the electrophotographic photosensitive member (1) to the circumference φc of the intermediate transfer belt (7) is changed.
φd was changed to 2.0. Example 2 is applied to this image forming apparatus.
Then, the electrophotographic photosensitive members of Comparative Example 2 were attached, and as Example 3 and Comparative Example 4, image exposure corresponding to a black halftone image was performed in a single color mode from a scanning optical device (3), and a multicolor developing device (4 The black halftone image was printed by the black toner developing unit provided in (1), and the density difference in the image was measured with a Macbeth densitometer. In the three-color mode, the timing is changed so that image exposure is performed at the same position on the electrophotographic photosensitive member (1), and image exposure corresponding to a gray halftone image is performed from the scanning optical device (3), and yellow development is performed. The color unevenness of the gray halftone image developed and output by the unit, the magenta developing unit, and the cyan developing unit was visually evaluated. The potential unevenness ΔVL in the circumferential direction of the photoreceptor was measured by removing the black toner developing unit of the multicolor developing device (4), attaching a surface voltmeter to the position, and measuring the potential unevenness in the circumferential direction. The resolution Rs of the scanning optical device (3) at the time of image exposure is laser power modulation, PWM
400dpi, 600dpi, 800d
pi were evaluated. Table 6 shows the results.

[0053]

[Table 6] Although the color unevenness is improved as compared with Example 2 and Comparative Example 2,
Since the timing was changed so that the image exposure was performed at the same position on the electrophotographic photosensitive member (1), the printing speed was significantly reduced.

Comparative Example 5 An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the silicone oil was changed to 0.03 part of (Chemical Formula 13) in Table 1. Repelling occurred in the generated layer coating film. Therefore, subsequent image evaluation and potential measurement could not be performed.

[0055]

As is apparent from the above detailed and specific description, the present invention provides an electrophotographic photosensitive member used in an image forming apparatus, comprising an undercoat layer, a charge generation layer, and a charge transport layer.
When the charge generation layer contains silicone oil, and the potential unevenness ΔVL in the circumferential direction of the electrophotographic photosensitive member by image exposure and the resolution Rs of image exposure by laser light satisfy the following formula (1), the resolution is improved. Even if it rises, it is possible to make subtle coating unevenness less likely to appear in the image by inexpensive means.

ΔVL ≦ 12000 / Rs Equation (1) As means for varying the resolution Rs of image exposure with laser light, means such as laser power modulation, laser spot diameter change, and pulse width (PWM) modulation may be used. It is possible. In addition, after developing toner of at least three colors for each color, the configuration is such that the development of each color is superimposed at the same position on the intermediate transfer body by a position sensor provided on the intermediate transfer body. Accordingly, it is possible to provide an image forming apparatus without color shift. Further, the image forming apparatus is an image forming apparatus configured to transfer a toner image onto an intermediate transfer member, and a ratio φc / φd of a peripheral length φd of the electrophotographic photosensitive member and a peripheral length φc of the intermediate transfer member. Is a non-integer, it is possible to provide an image forming apparatus free from image density unevenness and color unevenness even if the image forming apparatus is downsized. Further, since the image forming apparatus is a reversal developing type electrophotographic apparatus using one-component non-magnetic toner, it is possible to provide an image forming apparatus that satisfies halftone, line reproducibility, and solid density. . Further, by performing the image exposure of the image forming apparatus while changing the laser light amount in two or more steps, it is possible to provide an image forming apparatus excellent in reproducibility of halftone such as halftone. Further, the charge generation layer of the electrophotographic photoreceptor is formed by dip coating, and the silicone oil content in the charge generation layer coating solution is 1.0 to 10 wt. %, It is possible to form an electrophotographic photosensitive member having less coating unevenness and to provide an electrophotographic photosensitive member having no image density unevenness and color unevenness. Further, by setting the viscosity of the silicone oil in the charge generating layer coating liquid to 50 to 200 cp, a charge generating layer with less coating unevenness is formed, and an electrophotographic photosensitive member free from image density unevenness and color unevenness is provided. This is an extremely excellent effect that the following is possible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus of the present invention.

FIG. 2 is a view schematically showing a scanning optical device (3) of FIG. 1;

FIG. 3 is a cross-sectional view of an electrophotographic photosensitive member used in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 charging device 3 scanning optical device 3A laser beam 4 multicolor developing device 5 cleaning means (blade) 6 static elimination lamp 7 belt-shaped intermediate transfer body 8 roller 9 roller 10 roller 11 bias means (intermediate transfer) 12 transfer roller 13 Paper feeder (paper feed cassette) 13A paper 14 paper feed roller 15 transport roller pair 16 registration roller pair 17 fixing device 18 cleaning blade 22 laser light source 22D laser light 23 cylinder lens 24 polygon mirror 25 fθ lens 26 mirror 31 support 32 lower Pull layer 33 Charge generation layer 34 Charge transport layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 F term (Reference) 2H027 DA02 DD09 DE07 EA02 EB04 2H032 AA15 BA01 BA09 BA23 2H068 AA14 AA34 BB34 BB51 EA16 2H076 AB09 AB12 AB21 9A001 HH34 JJ35 KK42

Claims (7)

[Claims] An electrostatic latent image is formed on an electrophotographic photosensitive member by charging and image exposure with a laser beam, and the electrostatic latent image is visualized by a toner, and then transferred to reproduce a halftone. In the image forming apparatus, the electrophotographic photoreceptor comprises an undercoat layer, a charge generation layer, and a charge transport layer, and the charge generation layer contains silicone oil;
An image forming apparatus characterized in that the potential unevenness ΔVL in the circumferential direction of the electrophotographic photosensitive member by image exposure and the resolution Rs of image exposure by laser light satisfy the following expression (1). ΔVL ≦ 12000 / Rs Equation (1) 2. The method according to claim 1, wherein the development of each color is superimposed on the intermediate transfer member after developing the toner of at least three colors three times or more.
An image forming apparatus according to claim 1. 3. An image forming apparatus configured to transfer a toner image onto an intermediate transfer member, wherein a ratio φc / φd of a peripheral length φd of the electrophotographic photosensitive member to a peripheral length φc of the intermediate transfer member is not satisfied. The image forming apparatus according to claim 1, wherein the image forming apparatus is an integer. 4. The image forming apparatus according to claim 1, wherein the image exposure with the laser light is performed by changing a laser light amount in two or more steps. 5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a reversal developing type electrophotographic apparatus using a one-component non-magnetic toner. 6. A charge generation layer is formed by dip-coating a charge generation layer coating solution comprising a silicone oil, an organic pigment, a binder resin, and an organic solvent onto the electrophotographic photoreceptor, and the charge generation layer coating solution is formed. An electrophotographic photoreceptor, wherein the content of silicone oil therein is from 1.0 to 10% by weight of the binder resin. 7. The silicone oil has a viscosity of 50 to 50.
The electrophotographic photoreceptor according to claim 6, wherein the electrophotographic photosensitive member is 200 cp.