JP2006047576A - Electrophotographic photoreceptor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which can output an image of high picture quality with excellent gradation reproducibility and reproducibility of characters in low contrast, and to provide a process cartridge and an electrophotographic apparatus using the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor has a charge generating region formed by jetting a coating liquid containing at least a charge generating substance by an ink jet method and a charge transporting layer containing at least a charge transporting substance on a conductive supporting body, wherein the charge generating region is formed as dispersed in lines. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copying machine using an electrophotographic process, an electrophotographic photosensitive member used in a printer, and a manufacturing method thereof. More specifically, the present invention relates to a line for generating charge that can obtain high image quality. The present invention relates to an electrophotographic photosensitive member and a method for producing the same, wherein the electrophotographic photosensitive member is dispersed in a shape.

  Conventionally, the photoconductor used in the electrophotographic system includes a photoconductive layer mainly composed of selenium or a selenium alloy on a conductive support, and inorganic photoconductive materials such as zinc oxide and cadmium sulfide. Are generally known, such as those in which binder is dispersed in a binder, and those using an amorphous silicon-based material. However, cost, productivity, high degree of freedom in designing a photoreceptor, non-polluting, etc. Therefore, organic photoreceptors are widely used.

  The organic electrophotographic photoreceptor includes a photoconductive resin typified by polyvinylcarbazole (PVK), a charge transfer complex type typified by PVK-TNF (2,4,7-trinitrofluorenone), Known are pigment-dispersed type typified by phthalocyanine-binder resin, and function-separated type photoconductors that use a combination of a charge generation material and a charge transport material. However, due to sensitivity, durability, and freedom of design A function-separated type photoreceptor in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated on a conductive support is common.

  The mechanism of electrostatic latent image formation in this function-separated type photoreceptor is that when the photoreceptor is charged and irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generation material in the charge generation layer, The charge generation material that has absorbed the light generates charge carriers, which are injected into the charge transport layer, move in the charge transport layer according to an electric field, and neutralize the charge on the surface of the photoreceptor to neutralize the electrostatic latent. It forms an image. In function-separated type photoreceptors, it is known and useful to use a combination of a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly from the visible region to the near infrared region. It is.

  However, in the case of the above-described function-separated type photoreceptor, since the distance from the charge generation layer to the surface of the charge transport layer is long, there is a problem that the carrier is diffused during transport and the resolution is lowered. In other words, the carriers are attracted to the surface of the charge transport layer and transported, but at that time, they are also diffused in the lateral direction, the carrier diameter is larger than the beam spot diameter corresponding to one dot, and the adjacent image. The dot area is entered (see FIG. 1).

  Furthermore, since the energy distribution of the exposure beam follows a Gaussian function (normal distribution), the tail is widened, and the carriers generated by the light at the bottom are easy to diffuse into the adjacent image dot area, further improving the resolution. (See FIG. 2... 600 dpi, beam diameter 68.9 μm).

  Further, in an electrophotographic image forming apparatus, a beam spot diameter of a laser beam that exposes a photosensitive drum (a circle connecting regions that indicate an amount of light of 1 / e ^ 2 of the peak value of the light intensity distribution of the laser beam). Most of the diameters are in the range of 50 μm to 80 μm. On the other hand, when the resolution is 1200 dpi, the length per pixel is 21.2 μm, which is considerably smaller than the above beam diameter. However, the beam diameter is determined by the wavelength of the laser, the focal length of the optical system, and the aperture diameter, and reducing the beam diameter alone involves problems such as an increase in the size of the apparatus. There is a background that cannot be made smaller.

  The problem that the beam spot diameter is larger than the length per pixel and the problem that occurs in the above-described function-separated type photoconductor (laminated photoconductor), that is, when the photocarrier passes through the charge transport layer. When combined with the problem that photocarriers diffuse into the surface area of the charge transport layer and enter adjacent pixel areas, conventional image forming apparatuses have a sharp electrostatic latent image (potential (charge (charge)). ) There is a problem that it is difficult to form an electrostatic latent image having a high contrast.

  When such an electrostatic latent image with a small potential contrast is formed through development, transfer, and fixing processes, the following phenomenon that leads to deterioration in image quality may occur. However, it became clear by experiments conducted by the inventors.

“First image quality degradation phenomenon: disappearance of fine lines”
When one dot line (thin line) is formed when the resolution is high (for example, 1200 dpi), the dot image disappears in the output image, and the phenomenon that it is not reproduced appears. Even when the resolution is small (for example, 600 dpi), when half dots (writing with a small value at the time of multi-value writing) writing are performed, fine lines disappear in the same manner and are not reproduced. That phenomenon occurs.
These thin line images and images having characteristics close to those exist as low-contrast images (images such as lines and characters that appear to be very light gray) even in general images. For this reason, even in a general image, a reduction in image quality such as a decrease in reproducibility of a low contrast image is caused.

“Second image quality degradation phenomenon: abrupt density change in highlight area in gradation image”
When a gradation image such as a photographic image or a graphics image is subjected to pseudo halftone processing with a high number of lines and output as an image, a highlight portion (an area having a reflection density of about 0 to 0.2) ) Causes a sudden change in density. Such a rapid density change in the highlight portion in the gradation image causes a phenomenon in which a gradation boundary that does not exist on the original image, called a pseudo contour, appears. Since the pseudo contour is an abnormal image that gives a sense of incongruity in a gradation image, it is a major factor in image quality degradation.

  On the other hand, in Patent Document 1, in an electrophotographic photosensitive member in which at least a photosensitive layer is formed on a conductive substrate, the photosensitive layer includes a charge generation layer and a charge transport region, and the charge generation layer includes the charge generation layer. An electrophotographic photosensitive member is provided that has a structure embedded in a hole provided in a transport region, but is expensive due to a complicated manufacturing process, and the region is separated by a surface layer. As a result, it is easy for foreign matter to adhere to and sink, and an abnormal image is likely to occur.

  According to Patent Document 2, in the function separation type photoreceptor in which a base, a carrier generation layer, and a carrier transport layer are sequentially laminated, at least the light-shielding mask pattern layer that blocks part of image exposure light is included in the carrier. An electrophotographic photoreceptor characterized by being provided on the surface of the generation layer is provided, but it is also expensive due to the complicated manufacturing process, and contamination is caused by the material of the shading mask pattern, resulting in electrostatic characteristics. The above problem occurs.

  Further, in Patent Document 3, in a laminated electrophotographic photosensitive member including a charge generation layer and a charge transport layer, the charge transport layer contains a photocurable resin and other resin components, and when the charge transport layer is formed. By irradiating light in a wavelength region capable of curing the photocurable resin in a lattice shape, a portion where the content of the photocurable resin is larger than the unexposed portion is formed in a lattice shape, and the lattice-shaped exposed portion is An electrophotographic photosensitive member is provided in which the surface resistance or volume resistance is a region larger than that of the unexposed portion. However, it is expensive because the manufacturing process is complicated, and a photocurable resin is used. In general, the carrier mobility is lowered, and the photoresponsiveness as a photoreceptor is greatly lowered. Further, since the pattern is formed in a lattice pattern, it cannot be said that the effect on the resolution reduction is great.

  According to Patent Document 4, in an image forming apparatus that forms a visible image by charging, image exposure, and development on the surface of an image carrier on which a photoconductive photosensitive layer is formed, a potential is applied to the image exposure. Although an image forming apparatus is provided in which minute regions that do not attenuate are formed by being dispersed in the photosensitive layer, it has an effect on improving solid and graphic image density uniformity, It seems that there is no effect in improving the resolution. Also, the production method is formed by laser beam irradiation, and it is considered that the process is complicated and the influence of carbides and the like generated by laser beam irradiation on the electrostatic characteristics cannot be ignored.

In the invention in Patent Document 5, a photosensitive member having a lattice structure is provided on the surface of the photosensitive drum, and the photosensitive member having the lattice structure includes an insulating member and a photoconductive member. The pitch of the photoconductive member is equal to the scanning resolution of the laser beam, and the width of the photoconductive member is formed to be approximately half the pitch. The insulating member and the photoconductive member are provided on a conductive plate, and the photoconductive member has a structure in which a high resistance layer and a low resistance layer are sequentially laminated on a charge generation layer. is there.
With such a configuration, it is possible to eliminate density unevenness and color unevenness due to fluctuations in the scanning interval of the laser beam caused by fluctuations in the photosensitive member speed with a simple configuration and at low cost.

Furthermore, the photoconductor described in Patent Document 5 is an electrophotographic photoconductor in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate, and the charge contained in the coating solution for charge generation layer formation use. A charge generation layer is formed by a spray coating method using a coating solution for charge generation layer application in which the average particle size (median diameter) of the generated substance is 0.05 to 0.4 μm. .
With such a configuration, it is possible to manufacture an electrophotographic photoreceptor that is resistant to image defects, particularly interference fringes, that occur when single-wavelength light is used as image exposure light.

In the invention in Patent Document 6, a positively charged electrophotographic photosensitive member in which a photosensitive layer containing a charge generation material and a charge transport material is provided on a conductive substrate includes a perylene pigment that satisfies certain conditions (details omitted). It is characterized by that.
With such a configuration, a positively charged electrophotographic photosensitive material having spectral sensitivity in a high sensitivity long wavelength region, no image defects, durability against ozone, nitrogen oxides or ultraviolet rays, and excellent image stability. The body is going to be able to provide.

  Prior arts (Patent Document 1: Japanese Patent Laid-Open No. 2000-231203, Patent Document 2: Japanese Patent Laid-Open No. 2001-75301, Patent Document 3: Japanese Patent Laid-Open No. 11-258837, Patent Document 4: Japanese Patent Laid-Open No. 11-338170) In addition to the problems described above (cost increase due to the complexity of the production method, problems such as a reduction in durability due to non-uniformity of the light shielding pattern and the charge transport layer), ( 1) There is a problem that it is difficult to control the optical writing position in the sub-scanning direction (the circumferential method of the photosensitive drum). (2) It cannot be said that the method is sufficiently efficient in forming an electrostatic latent image having a large potential contrast.

Optical writing on the photosensitive member by the laser beam is performed by scanning the photosensitive member with the laser beam by the rotation of the polygon mirror. Normally, the rotation of the photosensitive drum and the rotation of the polygon mirror are asynchronous, so that in the sub-scanning direction (the circumferential direction of the photosensitive drum substantially perpendicular to the main scanning direction of the writing light) The beam spot position is not constant.
For this reason, if the charge generation region is formed in a lattice shape as in the prior art, the phenomenon that the charge generation region of the photosensitive drum and the beam spot position are shifted in the sub-scanning direction inevitably occurs.
That is, it is impossible to make the beam spot of the laser beam coincide with the center of the charge generation region (when the rotation of the photosensitive drum and the rotation of the polygon mirror are asynchronous). (On the other hand, since the position of the laser spot is controlled by an LD drive circuit or the like in the main scanning direction, it can be matched with considerably higher accuracy than in the sub scanning direction.)
Even when the rotation of the photosensitive drum and the rotation of the polygon mirror are synchronized, there is a variation in both the rotation of the photosensitive drum and the rotation of the polygon mirror. In this case as well, the beam spot position is shifted in the sub-scanning direction. It is extremely difficult to control and write to the target position.

  In the prior art described above, the generation ratio (so-called sensitivity) of photocarriers generated in CGL is constant in any part of CGL (any part of the unmasked part). In such a configuration, when combined with the current situation in which the beam spot diameter cannot be actively reduced, the photocarrier generated in the unmasked portion is almost constant in the area where the mask is not applied. Become. In this case, the photocarrier generation region is slightly concentrated by the mask region. However, since the effect is limited to the size of the mask region, an electrostatic latent image having a sufficiently large contrast ( There has been a problem that it is impossible to obtain an electrostatic latent image having such a large contrast that the above-mentioned problems such as disappearance of fine lines and abrupt density change in a highlight portion in a gradation image do not occur.

  For the above problem (problem in which an electrostatic latent image having a sufficiently high contrast cannot be formed), the mask area is further increased (the charge generation area is reduced), and the photocarrier generation location is set to one pixel. Improvement is also possible by limiting to the central part. However, in this case, there is a new problem that a so-called solid image (an image in which toner is uniformly attached to the entire region) cannot be obtained. This is because if the masked area is made large, the charge in this part cannot be canceled by writing, and toner cannot adhere to this part.

JP 2000-231203 A JP 2001-75301 A JP-A-11-258837 JP 11-338170 A Japanese Patent Laid-Open No. 11-52591 JP 7-306538 A

  That is, an object of the present invention includes a charge generation layer having at least a charge generation material on a conductive support, and a charge transport layer containing at least a charge transport material, and the charge generation layer is dispersed in a line as a minute region. And an electrophotographic photosensitive member having a structure in which the thickness of each linear charge generation region increases toward the center. It is an object of the present invention to provide an electrophotographic photoreceptor capable of uniformly adhering toner to the entire surface of a solid image while forming an electrostatic latent image having a sufficiently large contrast. It is not necessary to completely control the writing position control accuracy in the sub-scanning direction, and an electrostatic latent image having a sufficiently large contrast can be formed. It is an object of the present invention to provide an image forming apparatus, and to provide an image forming apparatus capable of uniformly adhering toner to the entire surface of a solid image while forming an electrostatic latent image having a sufficiently large contrast. That is.

As a result of intensive studies, the present inventors have found that the above problem can be solved by forming the charge generation layer as a fine region dispersed in a line as compared with the conventional electrophotographic photosensitive member and manufacturing method. (FIG. 3).
Further, since the material itself constituting the present invention does not use a light-shielding material, a curable material, or the like, it can be used without changing from a conventional photoconductor, and uses a simple and accumulated photoconductor technology. As a result, it is possible to easily design a photoreceptor corresponding to high sensitivity and high image quality.

（５）「前記電荷発生物質に含有される電荷発生物質の平均粒径が０．２μｍ以下であることを特徴とする前記（１）乃至（４）の何れかに記載の電子写真感光体。」
（６）「前記電荷発生領域が、電荷発生領域塗工液をインクジェット法を用いて噴射することにより形成されてなることを特徴とする前記（１）乃至（５）の何れかに記載の電子写真感光体の製造方法。」
（７）「前記インクジェット法がピエゾ方式であることを特徴とする前記（６）に記載の電子写真感光体の製造方法。」
（８）「前記（１）乃至（５）の何れかに記載の電子写真感光体を少なくとも有することを特徴とするプロセススカートリッジ。」
（９）「前記（１）乃至（５）の何れかに記載の電子写真感光体を少なくとも有することを特徴とする画像の出力を行う画像形成装置。」 That is, the said subject is achieved by (1)-(9) of this invention.
(1) “Having a charge generation region having at least a charge generation material on a conductive support and a charge transport layer containing at least a charge transport material, the charge generation region is formed by being dispersed in a line. An electrophotographic photoreceptor characterized by. "
(2) “having a charge generation region having at least a charge generation material on a conductive support and a charge transport layer containing at least a charge transport material, wherein the charge generation region is dispersed in a line, Further, the electrophotographic photosensitive member is characterized in that each line-shaped charge generation region has a structure in which the thickness increases as it approaches the center line. "
(3) “The electrophotographic photosensitive member according to (1) or (2) above, wherein the pitch of the line-shaped charge generation region is equal to the resolution in the main scanning direction of the image forming apparatus.”
(4) The thickness distribution of the charge generation region is represented by a graph in which the vertical axis represents the thickness (height) of the charge generation region and the horizontal axis represents the distance between the center lines of the charge generation region. In this case, the half-value width W (twice the distance from the central portion to the location where the thickness is h / 2 when the thickness of the charge generation region in the central line portion is h) corresponds to one pixel. The electrophotographic photosensitive member according to (2) above, wherein the relationship with the length L (= “the interval”; for example, L = 21.2 μm at 1200 dpi) satisfies the following relational expression: . "

(5) The electrophotographic photosensitive member according to any one of (1) to (4), wherein the average particle size of the charge generation material contained in the charge generation material is 0.2 μm or less. "
(6) The electron according to any one of (1) to (5), wherein the charge generation region is formed by ejecting a charge generation region coating solution using an inkjet method. Method for producing a photoconductor. "
(7) “The method for producing an electrophotographic photosensitive member according to (6) above, wherein the inkjet method is a piezo method.”
(8) “A process cartridge including at least the electrophotographic photosensitive member according to any one of (1) to (5)”.
(9) “An image forming apparatus for outputting an image, comprising at least the electrophotographic photosensitive member according to any one of (1) to (5)”.

  The present invention of claim 1 is characterized in that the charge generation region is formed as a minute region dispersed in a line. There may be a gap (narrow region without charge generation material) between the line-shaped charge generation regions, or there may be a narrow region with a very small amount of charge generation material. By adopting such a configuration, as in the prior art (for example, Japanese Patent Laid-Open No. 2000-231203 [0011] described in the section of the prior art), the location where photocarrier generation occurs due to laser beam exposure is limited. By doing so, the problem that the latent image spreads and an electrostatic latent image with poor contrast is formed can be solved. (In claim 1, since there is a line-shaped charge generation region extending in the sub-scanning direction, such an effect cannot be expected so much in the sub-scanning direction, but an effect can still be obtained in the main scanning direction. )

Further, the present invention of claim 1 can solve the problem that the position of the laser beam on the photosensitive drum, which is a problem in the prior art, cannot be accurately controlled in the sub-scanning direction. Become. This problem is almost inevitably caused in the so-called LD raster method (method in which a laser beam is scanned on the photosensitive drum by rotating a polygon mirror). According to the first aspect of the present invention, since the charge generation region has uniform characteristics regardless of the position in the sub-scanning direction, the position of the laser beam is shifted on the photosensitive drum in the sub-scanning direction. However, there is almost no impact. In contrast, when a conventional photosensitive drum that forms a charge generation region in a lattice shape is used, the laser that contributes to the exposure of the charge generation region when the writing position by the laser beam is shifted in the sub-scanning direction. Therefore, the amount of photocarrier generated in the charge generation region changes. As a result, there arises a problem that the density of the image occurs in the sub-scanning direction.
As described above, in the photoconductor of claim 1, by forming the charge generation region in a line shape, the place where photocarrier generation occurs can be limited, and an electrostatic latent image with good contrast can be formed. Can be formed. As a result, even when a grayscale image such as a photographic image or a graphics image is subjected to pseudo halftone processing with a high number of lines and image output is performed, a highlight portion (with a reflection density of 0 to 0. 0). An image with good reproducibility can be obtained without a sudden density change in the region of about 2). In addition, the reproducibility of small characters and fine lines can be improved.
Further, in the configuration of the first aspect, density unevenness (darkness of the image) in the sub-scanning direction that occurs due to the shift of the exposure position by the laser beam in the sub-scanning direction, which has occurred in the prior art. Occurrence can be realized in combination with the above effects.
Furthermore, compared with the conventional method, (1) “It is expensive because the manufacturing process is complicated”, (2) “Adhesion of foreign matter due to separation of regions in the surface layer” (Japanese Patent Laid-Open No. 2000-231203). (3) “Contamination occurs depending on the material of the light-shielding mask pattern” (Japanese Patent Laid-Open No. 2001-75301), (4) “Reduction in photocarrier mobility when using a photo-curing resin” 11-258837) and (5) "adverse effects on electrostatic characteristics of hydrocarbons generated by laser beams" (Japanese Patent Laid-Open No. 11-3381707) can all be solved. is there.

According to the second aspect of the present invention, the charge generation regions are formed as fine regions dispersed in a line shape, and the thickness of each line-shaped charge generation region increases toward the center line portion. It is configured. Thereby, at the time of exposure, more photocarriers can be generated in the central portion than on both sides of the pixels constituting the image. As a result, the problem pointed out in the section of [Prior Art], that is, when the photocarrier passes through the charge transport layer in the function-separated type photoreceptor, it spreads in the surface direction (lateral direction) of the photosensitive layer. It is possible to solve the problem that the resolution is deteriorated. (In the sub-scanning direction, the latent image spreads to the same extent as in the past, but in the main scanning direction the spread of the latent image can be suppressed.)
According to the second aspect of the present invention, because of the structure of the charge transport region, more photocarriers are generated in the central portion than on both sides of the pixel. Compared to a photoconductor configuration in which a certain amount of photocarriers are generated (the amount of photocarriers generated on both sides of the pixel and the central portion is substantially the same), the resolution described above is reduced. It greatly contributes to solving the problem. As a result, even when a grayscale image such as a photographic image or a graphics image is subjected to pseudo halftone processing with a high number of lines and an image is output, the highlight portion (reflection density is 0 to 0). (Region of about .2), there is no rapid density change and an image with good reproducibility can be obtained.
Furthermore, in the present invention of claim 2, the charge generation region exists on both sides of the pixel. (Of course, the thickness of the charge transport layer is made smaller than that of the central portion of the pixel.)
For this reason, a small amount of photocarriers are also generated in the peripheral portion. This is important when a solid image (high density image) is formed. In the prior art, in order to solve the resolution problem described in the previous paragraph, a method for limiting the photocarrier generation region has been proposed. However, in the case of a solid image, it is necessary to attach toner to the entire surface. It is necessary to cancel the charge on the surface of the photosensitive member by a photo carrier even in a region where no occurrence of the phenomenon occurs. For this reason, it has been difficult for the conventional method to achieve both resolution and solid image. On the other hand, in the present invention of claim 2, the photo carrier is generated so that the solid image can be reproduced (the gap is filled) with respect to the compatibility with the black solid. Small amount compared to the center portion of the pixel). This makes it possible to achieve both resolution and solid image (high density). According to the second aspect of the present invention, there is provided a photoconductor with less light fatigue when repeatedly used continuously. Of the beam diameter of the exposure laser beam, the region portion within the beam spot diameter showing an intensity of 1 / e ^ 2 or more of the peak intensity value includes a light amount of about 86.5% of the total light amount of the beam diameter, Therefore, the intensity (amount) of irradiation light in the peripheral area excluding this region is considerably small, and the amount of charge generation material in the peripheral area is small, so that photocarriers in this peripheral area (for image formation) As a result, the absolute number of photocarriers captured during movement is significantly reduced.
Further, by adopting the configuration according to claim 3 of the present invention, as a result of an image output experiment conducted by the inventor, it is possible to improve highlight reproducibility and to achieve a sufficient reflection density even in a solid image. did it.
According to the present invention of claim 4, in addition to the present invention of claim 1, the effect shown in claim 1 is made more remarkable by making the pitch of the charge generation regions equal to the resolution of the image forming apparatus. Become.
Further, according to the present invention of claim 5, when the average particle diameter of the charge generation material contained in the charge generation material is 0.2 μm or less, dot reproducibility is improved and unevenness of the entire image is reduced. A good image can be obtained.
Further, according to the present invention of claim 6, by forming the charge generation region using the ink jet method, the dot can be formed with a very simple manufacturing apparatus and at a low cost compared to the conventional case. Is possible.
Further, according to the present invention of claim 7, by using a piezo method as the ink jet method, it is possible to prevent alteration of the charge generation region coating solution which is easily altered by heat, and when coating is performed by a foaming jet method. An image-like black spot which is a concern can be prevented, and a manufacturing method which can bring out the effects of the present invention very well can be obtained.
Further, according to the present invention of claim 8, a process cartridge suitable for exhibiting the effects described in the inventions of claims 1 and 2 is realized.
According to the ninth aspect of the present invention, an image forming apparatus suitable for achieving the effects described in the first and second aspects of the invention is realized.

Next, an ink jet method used for producing a charge generation region formed by dispersing in a line on the photosensitive member used in the present invention will be described.
The ink jet method is a method used in an ink jet printer. Recently, an ink jet recording method using this ink jet method has begun to spread widely. This ink jet recording method is a printing method in which printing is performed by causing small droplets of an ink composition to fly and adhere to a recording medium such as paper. An ink jet recording apparatus using this method has a feature that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. For this reason, ink jet recording apparatuses have come to be used as digital printing machines, plotters, CAD output devices, and the like. In particular, since the ink jet recording apparatus can print a digitally processed sentence or image, it can store a document or an image original semipermanently and can print the contents. The ink jet recording apparatus can realize high analysis and high pixel printing by discharging ink composition droplets from a recording head under appropriate system processing.

  That is, the ink jet method can attach small droplets to a specific place so that photographic image quality can be output, and there is almost no loss as a liquid. Therefore, it is possible to form a high-quality coating film at low cost as a liquid. In addition, as used in digital equipment, the ON / OFF of droplet flight can be digitally controlled, so that liquid can be output and applied only where needed, and unnecessary parts can be easily removed. It can be uncoated. In addition, equipment such as nozzle heads used in the ink jet method can be easily obtained at low cost and with high quality and high stability due to the widespread use of ink jet printers. Does not require large-scale equipment. Further, as can be seen from the recent trend of inkjet printers, productivity can be dealt with by increasing the number of nozzles, and productivity can be easily improved.

  In addition, as an ink jet system used in the manufacturing method by the ink jet method of the present invention, a foaming jet type using an electrothermal transducer as an energy generating element, a piezo jet type using a piezoelectric element, or the like can be used. However, the piezo-type ink jet method only applies pressure to the ink and basically has no degradation effect on the ink, whereas the bubble-type ink-jet method instantaneously moves the micro heater embedded in the nozzle. In any case, since the ink is ejected by heating to 200 to 300 ° C. and generating bubbles, the ink has a deterioration action such as kogation. Due to the influence of this kogation, the background stain of the image may occur, and the piezo jet type is preferably used in consideration of the influence of heat or the like on the ink, that is, the coating liquid. Also, by changing the ink jet nozzle and pressurizing / heating time, the amount of ink per ink drop and the amount of ink applied per landing part can be set arbitrarily. It becomes possible to control the dot shape (diameter) of the layer. The coating liquid for forming a charge generation region for inkjet ink according to the present invention can be obtained by adjusting the surface tension and viscosity of the charge generation region by adjusting the type and amount ratio of the liquid medium. Although spreadability can be adjusted, the surface tension and viscosity are slightly higher than those of ordinary inkjet inks because high permeability to the substrate and intermediate layer is not so high to ensure quick drying. Is acceptable and preferred. Further, for example, a part of the dispersion medium used at the time of preparing the coating solution for forming the charge generation region can be used for the ink by substituting with another solvent having a desired boiling point and solubility. Further, it may be supplemented by double printing.

Next, the electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 4 shows a structure in which a charge generation layer (35) mainly composed of a charge generation material and a charge transport layer (37) containing a charge transport material are laminated on a conductive support (31). ing.
FIG. 5 shows a configuration in which an intermediate layer (33) is provided between the conductive support (31) and the charge generation layer (35) in FIG.
(These FIGS. 4 and 5 are cross-sectional views when the photosensitive drum is cut in the main scanning direction. Therefore, the charge generation region has a line shape extending in the front and back direction of the paper surface.)
The line width and line pitch of the charge generation layer formed in the line shape can be measured by using an optical microscope, a laser microscope, or the like.

As the conductive support (31), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium by vapor deposition or sputtering, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel plates, etc. and methods such as extrusion and drawing After forming the tube, it is possible to use a tube subjected to surface treatment such as cutting, superfinishing or polishing. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (31).

In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) of the present invention.
Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is made conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and polytetrafluoroethylene on a suitable cylindrical substrate. What provided the layer can also be used suitably as the electroconductive support body 31 of this invention.

Next, the charge generation region (35) is a layer mainly composed of a charge generation material, in which the charge generation material, the binder resin or the like is dispersed or dissolved in an appropriate solvent, and this is formed on the conductive support or in the middle. It can be formed by coating and drying on the layer.
For the charge generation region (35), a known charge generation material can be used, and for the charge generation region (35), all known charge generation materials can be used, and representative examples thereof include titanyl phthalocyanine. , Phthalocyanine pigments such as vanadyl phthalocyanine, copper phthalocyanine, hydroxygallium phthalocyanine, metal-free phthalocyanine, monoazo pigments, disazo pigments, asymmetric disazo pigments, trisazo pigments and other azo pigments, perylene pigments, perinone pigments, indigo pigments, pyrrolopyrrole Known materials such as pigments, anthraquinone pigments, quinacridone pigments, quinone condensed polycyclic compounds, squalium pigments, and the like are usefully used. These charge generating materials can be used alone or in combination of two or more.

  In the charge generation region (35), the charge generation material is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is applied onto a conductive support. And formed by drying. The particle size of the charge generation material is preferably 0.2 μm or less. In the case of 0.2 μm or more, since dots are not formed cleanly and uniformly, the resolution of isolated dots is lowered. In particular, the influence becomes significant when a high resolution of 1200 dpi or more and a writing system of a small diameter beam are used.

  As the binder resin used in the charge generation region (35) as required, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly -N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone Etc. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material. The binder resin may be added before or after dispersion.

Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, and ligroin. In particular, ketone solvents, ester solvents, and ether solvents are preferably used. These may be used alone or in combination of two or more.
The charge generation region (35) is mainly composed of a charge generation material, a solvent, and a binder resin, and includes any additive such as a sensitizer, a dispersant, a surfactant, and silicone oil. May be.
As a coating method of the coating solution, an inkjet method is preferable as shown in the present invention.
The film thickness of the charge generation region (35) is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer (37) can be formed by dissolving or dispersing the charge transport material and the binder resin in an appropriate solvent, and applying and drying the solution on the charge generation region. Moreover, it is possible and useful to add one or two or more kinds of plasticizers, leveling agents, antioxidants, lubricants and the like as necessary.
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. These may be used alone or in combination of two or more.
As a coating method of the coating solution, methods such as dip coating, spray coating, beat coating, nozzle coating, spinner coating, ring coating, and the like can be used.

Charge transport materials are classified into hole transport materials and electron transport materials.
Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

  Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, etc. Other known materials may be used. These charge transport materials may be used alone or in combination of two or more.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
The thickness of the charge transport layer varies depending on the system used (particularly, the charging potential), but is preferably 5 μm or more.

A protective layer (not shown) may be formed on the charge transport layer (37) for the purpose of improving durability.
As the protective layer, for example, a layer containing a hole transporting hydroxyarylamine having a hydroxy functional group and a polyamide film forming binder capable of forming a hydrogen bond with the hydroxy functional group (Japanese Patent Laid-Open No. 7-253683) ), A hydroxyarylamine compound having a hydroxy functional group in a thermosetting polyamide resin, a curing catalyst, a film cured by heating after coating (US Pat. No. 5,670,291), an alkoxysilyl group A layer cured with a charge transport compound and an alkoxysilane compound (JP-A-3-191358), a cured layer using an organopolysiloxane and colloidal silica, and a conductive metal oxide and an acrylic resin ( JP-A-8-95280), a conductive metal oxide having a silicon functional group Layer cross-linked with acrylate (JP-A-8-160651), layer cross-linked with conductive metal oxide with photocurable acrylic monomer or oligomer (JP-A-8-184980), charge containing epoxy group A layer cured with a transporting compound (Japanese Patent Laid-Open No. 8-278645), a diamond-like carbon containing hydrogen, or a layer of crystalline carbon containing amorphous carbon or fluorine (Japanese Patent Laid-Open No. 9-101625, Kaihei 9-160268, JP-A-10-73945, a layer mainly composed of cyanoethyl pullulan (JP-A-9-90650), a layer obtained by crosslinking a silyl acrylate compound and colloidal silica (JP-A-9-319130). No.), a layer using a polycarbonate graft copolymer (Japanese Patent Laid-Open No. 10-630) 6), a layer obtained by curing colloidal silica particles and a siloxane resin (Japanese Patent Laid-Open No. 10-83094), a layer cured with a charge transport compound containing a hydroxy group and an isocyanate group-containing compound (Japanese Patent Laid-Open No. 10-177268). No. gazette).
The film thickness of the entire protective layer is 1 μm to 10 μm, preferably 2 to 6 μm. If the protective layer thickness is extremely thin, the uniformity of the film may be reduced or sufficient wear resistance may not be obtained.If the thickness is extremely thick, there is an effect of an increase in residual potential. In some cases, the resolution or dot reproducibility may decrease due to an increase in light transmittance.

  In the photoreceptor of the present invention, an intermediate layer (33) can be provided between the conductive support (31) and the charge generation region (35). The intermediate layer (33) generally has a resin as a main component, but these resins are resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. It is desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. However, when the charge generation region is dispersed and formed in a line shape as shown in the present invention, the intermediate layer contains a filler and has a porous structure in order to improve the uniformity of the charge generation line width to be formed and to prevent bleeding and the like. It is preferable to have.

Further, fine powder pigments of metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the intermediate layer in order to prevent moire and reduce residual potential. These intermediate layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. Furthermore, various dispersing agents can be added. In addition, the intermediate layer of the present invention is provided with Al ₂ O ₃ by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used satisfactorily. However, unevenness in the charge generation region tends to cause unevenness in the image, particularly non-uniformity of the halftone density. Therefore, the intermediate layer is porous in the micron order so that the coating liquid does not bleed when adhering to the substrate. Such an intermediate layer is desirable. The thickness of the intermediate layer is suitably from 0 to 5 μm.

  In the photoreceptor of the present invention, another intermediate layer can be provided between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used 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 generally used coating method as described above is employed. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

  EXAMPLES Next, although this invention is demonstrated based on an Example, this invention is not limited by these Examples.

Example 1
Photoconductor structure <intermediate layer>
An intermediate layer coating solution having the following formulation was prepared.
"Interlayer coating liquid"
Polyamide resin (CM8000, manufactured by Toray Industries, Inc.) 2 parts Methanol 58 parts n-Butanol 40 parts This coating solution is dip-coated on an aluminum drum having a diameter of 30 mm and a length of 340 mm, dried at 120 ° C. for 20 minutes, and a film thickness of 0 An intermediate layer of 3 μm was prepared.

<Charge generation region>
Next, a charge generation region coating solution having the following formulation was prepared.
10 parts by weight of a trisazo pigment represented by the following structural formula (A) is added to a resin solution obtained by dissolving 4 parts by weight of polyvinyl butyral (BM-2: manufactured by Sekisui Chemical Co., Ltd.) in 150 parts by weight of cyclohexanone, and 72 hours by a ball mill. Dispersion was performed. After the completion of dispersion, 250 parts by weight of cyclohexanone and 200 parts by weight of 2-butanone were added and dispersed for 3 hours to prepare a charge generation region coating solution. The coating solution is applied and formed on the intermediate layer in the form of a line under the following conditions, and dried at 120 ° C. for 20 minutes to form a charge generation region (film thickness measurement method) having a thickness of about 0.3 μm at the center of the charge generation region. Was created in detail later (both ends 10 mm uncoated part).

Although some unevenness was observed due to bleeding and spreading of the coating solution, the coating solution was satisfactorily coated without any roughness or unevenness of the coating film. Moreover, since the coating width was controlled, the uncoated part was not wiped off, and the defect due to wiping (thickening of the coating film thickness at the end, splashing at the time of wiping) was good. The amount of coating solution used was about 0.5 ml.
The particle diameter of the charge generation material after dispersion was 0.07 μm. The particle size was measured by centrifugal sedimentation using CAPA-700 manufactured by Horiba.
In the present invention, the coating was performed by modifying a commercially available Seiko Electronics Industry IP-4000 A0 printer (compatible with oil-based pigment ink). A piezo type recording head was used. The ink in the ink cartridge can be replaced. In addition, the aluminum drum was remodeled so that it could be rotated at the ink adhering part and paper position. In addition, coating by the ink jet method can be controlled from a personal computer, and the liquid discharge amount (which changes the dot size) and the dot interval are controlled from the personal computer as well as the coating width.

  FIG. 3 is a diagram schematically showing the formation state of the charge generation region formed in a line shape on the photosensitive drum. The line-shaped charge generation region is a line extending in the circumferential direction of the photosensitive drum (corresponding to a so-called sub-scanning direction). The pitch of this line (one cycle of the line) corresponds to the length of one pixel of the image forming apparatus. (Equivalent to claim 3)

<Charge transport layer>
Next, a charge transport layer coating solution having the following formulation was prepared.

  7 parts by weight of the charge transport material represented by the structural formula (B) and 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 50,000) were dissolved in 100 parts by weight of tetrahydrofuran to prepare a charge transport layer coating solution. This coating solution was dip-coated on the charge generation region, dried at 130 ° C. for 20 minutes, and a charge transport layer having a thickness of 20 μm was applied to produce the photoreceptor of the example.

<Image output, image quality evaluation>
An image was output using the photosensitive drum that was prototyped by the above manufacturing method, and the image quality was evaluated.
As for image output, paying attention to two items of “good reproduction of fine lines” and “stable density change in highlight portion”, the following image output experiments were performed respectively. First, “good reproduction of thin lines” was evaluated by visual observation using an image output experiment machine having a resolution of 1200 dpi described below and using an image pattern with 400 lines shown in FIG. The case where a 400-line line image was reproduced was marked as ◯, and the case where a 400-line line image was not reproduced was marked as x. Whether or not the 400-line line image is set as a criterion for determination is based on the outline of the character part (not to become a rattling outline) and the color of the character when a low-contrast character / color character is printed with a printer. This is set as a substitute characteristic for reproducing both the reproducibility (the target color can be reproduced) and the like.
Next, with respect to “stable density change in the highlight portion”, an 8-bit Tiff image data including patches of 0 to 256 gradations (15 mm square) using an image output experimental machine with a resolution of 1200 dpi described below. Output image data (post-pseudo halftone processed data) that has been subjected to dither processing (screen screen number of about 170 lines, screen angle of 45 degrees, line screen type, quantization number of 2 bits, resolution of 1200 dpi) in advance Prepare and output an image using the output image data. The evaluation of the output image was performed using the result of measuring the reflection density (ID value) of the highlight portion (data 0 to 32) with a spectral reflection densitometer (model 938 manufactured by X-Rite). A linear equation is approximated with respect to the relationship between the reflection density value and the input data value, and a case where the value of R ^ 2 (R2 is ^two of the correlation coefficient) is 0.95 or more is set as ◯. The case where the value of ^ 2 was less than 0.95 was evaluated as x. The condition that the value of R ^ 2 of the linear expression approximation in the highlight portion (data 0 to 32) set as a criterion here is 0.95 or more is an abnormality called a pseudo contour in a gradation image This is set as a substitute characteristic for good reproduction without generating an image.

  Next, an experimental machine used for image output will be described. This experimental machine is an experimental machine modified on the basis of Ricoh's Imageo Color 5100, which is mainly a modified writing unit. In this experimental machine, a four-channel LD array in which four light emitting points (laser diodes) are formed in a line on one chip is used as an LD element. Thereby, a resolution of 1200 dpi was realized. In this experimental machine, the optical element and the aperture are adjusted so that the beam diameter is 60 (main scanning direction) × 60 (sub-scanning direction) μm on the photosensitive member position. Further, the amount of the stationary beam of the laser beam is adjusted and set by measurement using an optical power meter. In this experimental machine, the so-called pixel clock is 78.3 MHz, and the photosensitive drum is irradiated with a laser beam while being driven to modulate the laser emission based on the pixel clock. A latent image is formed. Further, the control for making the center line of the line-shaped charge generation region coincide with the writing position of the laser beam is performed as follows. Main scanning synchronization detection means including a photodiode element is arranged at a position where the laser beam scans outside the image area, the main scanning position of the laser beam is converted into a signal, and the pixel clock signal is controlled based on this signal. (Counter reset, phase adjustment, etc. to match scanning timing and LD light emission timing) realizes the above-mentioned control (control to match the center line of the line-shaped charge generation region with the writing position of the laser beam) To do.

Next, an image output experiment and results thereof will be described. The prototype photoconductor used in the experiment was produced by the method described in the section <Photoreceptor structure>. (CGM is trisazo pigment: structural formula (A).)
At this time, while adjusting various coating conditions of the coating liquid of the ink jet printer, the prototype photosensitivity is set so that the pitch of the charge generation region is 21.2 μm so as to correspond to 1200 dpi which is the resolution of this experimental machine. A body drum was made.
Details of the structure of the charge generation region are shown below. The line-shaped charge generation region has a substantially constant thickness (about 0.3 μm) in the line width direction and is formed on the intermediate layer (described in detail in <Photoreceptor Configuration>). . The line width at this time was set to 11 μm, which is about half of the length of 21.2 μm corresponding to one pixel with a resolution of 1200 dpi. (Fig. 7)

  As Comparative Example 1, a photosensitive drum having substantially the same configuration as that of Example 1 was prepared, and an evaluation experiment using image output was performed. However, in Comparative Example 1, unlike Example 1, the charge generation region was formed as a uniform layer (film thickness was about 0.3 μm and the same as Example 1). (Fig. 8)

Using the photosensitive drum (Example 1 and Comparative Example 1) produced in this way, an image is output, and the above two items ("400-line line image reproduction", "Highlight part is expressed by a linear expression). Approximation and R ^ 2 value of 0.95 or more ") were evaluated. (Comparative Experiment 1)
Table 1 shows the results of this experiment.

  From Table 1, it can be understood that the configuration of Example 1 can realize image output with high image quality (excellent gradation reproducibility and excellent low-contrast character reproduction). In addition, using the photosensitive drum having the configuration of Example 1 and Comparative Example 1, the above-described experimental machine includes a comprehensive test chart (a test including an image quality element such as a highlight portion, a low contrast character portion, and a solid portion). As a result, the results shown in Table 2 were obtained.

  As can be seen from Table 2, the configuration of Example 1 did not cause gradation skip in the highlight area, showed good low-contrast character reproduction, and could output a high-quality image. On the other hand, in the configuration of Comparative Example 1, such an image cannot be obtained, and the problem pointed out in the section of the prior art occurs.

(Examples 2-4, Comparative Examples 2-4)
Next, the result of an experiment conducted by making a prototype of a photosensitive drum in which the thickness of the center line portion of the charge generation region is increased will be shown. Examples 2 to 4 Table 3 shows the cross-sectional dimensions of the line-shaped charge generation region by the alphabet shown in FIG. The photosensitive drums of Examples 2 to 4 were prepared using the same formulation as that described in the section <Photoreceptor Configuration> of Example 1. By changing the protrusion amount of the coating solution for applying the charge generation region and applying it a plurality of times, the configuration shown in Table 3 below was realized.
In the prototype photoconductor drum, the sample in which the charge generation region was formed was used exclusively for charge generation region measurement without providing a charge transport layer. The charge generation region is measured using a Keyence laser microscope (model number: VK-8550) capable of measuring height information, the distance from the center of the charge generation region to the ridge, and the charge generation region. The height distribution was measured. In addition, since the height cannot be measured accurately when using the above-mentioned laser microscope (this is because the reflectance of the laser beam is low due to the charge generation region), after the gold plating is applied to the surface, the height of the charge generation region is high. Measuring. From the height distribution of the charge generation region thus obtained, W (half-value width) that is an index representing the cross-sectional shape of the charge generation region is derived by calculation. FIG. 9 is a schematic diagram (a cross-sectional view of the line-shaped charge generation region) representing W (half-value width) which is an index representing the cross-sectional shape of the charge generation region. When the height (thickness) is h, the width (W) of the region where half the height (thickness) = h / 2 is derived from such a measurement result.
Using the photosensitive drum thus produced, an image is output, and the above two items ("400-line line image reproduction", "Highlight part is approximated by a linear expression and the value of R ^ 2 is Table 3 below shows the results of evaluation of “0.95 or more”.

  From the results shown in Table 3, when W (half-value width), which is an index representing the shape of the charge generation region, is 0.65 or less, the “Invention is to be solved” as described in the section of the related art. It can be understood that the “problem” can be improved, and that “solid ID = 1.4 or more” can be achieved at the same time, and a good image quality can be realized.

  Moreover, as a result of outputting the above-described comprehensive test chart for the above-described Example 2 and Example 3, it was possible to confirm the output of a high-quality image.

It is explanatory drawing that a photo carrier diffuses during the charge transport layer movement in the past. It is the figure which showed the exposure amount by beam superimposition in the case of the length equivalent to the beam diameter> resolution in the past. FIG. 3 is a schematic diagram illustrating a photosensitive drum according to the first exemplary embodiment. FIG. 4 is a cross-sectional view of the photosensitive drum of the present invention when cut in the main scanning direction. FIG. 6 is another cross-sectional view when the photosensitive drum is cut in the main scanning direction. It is 400 lpi image pattern explanatory drawing (1200dpi) 2 is a diagram illustrating an example of a photoconductor configuration (cross-sectional view) of Example 1. FIG. FIG. 5 is a diagram showing an example of a photoconductor configuration (cross-sectional view) of Comparative Example 1. FIG. 6 is an explanatory diagram of a photoconductor configuration (cross-sectional view) example and a half-value width W of Comparative Examples 2 and 3;

Explanation of symbols

31 Conductive Support 33 Intermediate Layer 35 Charge Generation Region 37 Conductive Support

Claims (9)

It has a charge generation region having at least a charge generation material on a conductive support and a charge transport layer containing at least a charge transport material, and the charge generation region is formed by being dispersed in a line. Electrophotographic photoreceptor. The conductive support has a charge generation region having at least a charge generation material and a charge transport layer containing at least a charge transport material, and the charge generation regions are formed in a line-like shape, and each An electrophotographic photosensitive member characterized in that the line-shaped charge generation region has a structure in which the thickness increases as it approaches the center line. The electrophotographic photosensitive member according to claim 1, wherein the pitch of the line-shaped charge generation regions is equal to the resolution in the main scanning direction of the image forming apparatus. When the thickness distribution of the charge generation region is expressed by a graph in which the vertical axis represents the thickness (height) of the charge generation region and the horizontal axis represents the distance between the center lines of the charge generation region, L A value width W (twice the distance from the central portion to a location where the thickness is h / 2, where h is the thickness of the charge generation region in the central line portion), and a length L corresponding to one pixel, The electrophotographic photosensitive member according to claim 2, wherein the relationship satisfies the following relational expression.

5. The electrophotographic photosensitive member according to claim 1, wherein an average particle diameter of the charge generation material contained in the charge generation material is 0.2 μm or less. 6. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the charge generation region is formed by spraying a charge generation region coating solution using an ink jet method. The method for producing an electrophotographic photosensitive member according to claim 6, wherein the inkjet method is a piezo method. A process cartridge comprising at least the electrophotographic photosensitive member according to claim 1. An image forming apparatus for outputting an image, comprising at least the electrophotographic photosensitive member according to claim 1.

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