JP2006267885A - Electrophotographic device and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic device capable of detecting toner density with high precision and high stability for a long period, the electrophotographic device being capable of continuously outputting high-definition images with superior gradation stability even after its duration. <P>SOLUTION: The electrophotographic device has a cylindrical electrophotographic photoreceptor 1, a charging means 2, an exposing means 3, a developing means 4, a transfer means 5, a regular reflection toner density detecting means of detecting toner density on the peripheral surface of the electrophotographic photoreceptor 1 after development and before transfer, and an image density control means of controlling image density according to information on the toner density obtained from the regular reflection toner density detecting means, the electrophotographic device being characterized in that a surface layer of the electrophotographic photoreceptor contains a cured material obtained by curing and polymerizing a compound having a polymerizable functional group and the peripheral surface of the electrophotographic photoreceptor has a plurality of dimple-shaped recessed parts formed by causing powder to strike on the surface of the surface layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic apparatus such as a copying machine, a laser printer, and a fax machine, and a process cartridge used in the electrophotographic apparatus.

  Conventionally, the following methods are known as methods for stabilizing the image density of image forming apparatuses such as copying machines and printers (see, for example, Patent Documents 1 and 2).

  For example, a method for stabilizing image density by adjusting image processing (image control) is known. Specifically, a specific pattern (patch image) is formed on an image carrier such as a photosensitive drum (hereinafter also referred to as a photoreceptor) after the image forming apparatus is started and the warm-up operation is completed or during the output operation. Then, the density of the formed pattern is read, and γ correction is performed on the basis of the read density value (a γ curve is derived from the relationship between the drum surface potential after exposure and the density of toner formed on the drum, There is a method of stabilizing the quality of an image to be formed by changing the operation of a circuit for determining image forming conditions such as a correction circuit for adjusting to an appropriate color gradation.

  Further, when the image forming apparatus is used for a long period of time, there may occur a case where the density obtained by reading the pattern on the image carrier does not match the density of the actually printed image. For this reason, a method is also known in which a specific pattern is formed on a recording material and the image forming conditions are corrected by the density value.

  Furthermore, as a method for adjusting the toner density in the developing device, a method of replenishing toner by a method of detecting and controlling the amount of reflected light from the developer (developer reflection ATR) is known. Specifically, the toner excess / shortage amount required to return the patch image density to the initial density is calculated from the output signal of the density difference of the specific pattern (patch image) on the image carrier, and the toner replenishment amount is calculated as the developer. There is known a method of stabilizing the image density by adding and subtracting to and correcting the target value set in the reflection ATR and supplying the corrected toner supply amount.

  There are two types of sensors that form the specific pattern (patch image) on an image carrier such as a photosensitive drum and read the density of the formed pattern. One is a scattering type optical density sensor mainly used for toner density control, and the other is a regular reflection type optical density sensor mainly used for γLUT correction.

  The scattering type optical density sensor is a type of sensor that detects the patch density by increasing or decreasing the amount of scattered light from the toner and the image carrier. In the case of a color image forming apparatus, the reflectance with respect to the projected light is colored toner / photosensitive. Since the drum toner and the black toner are higher in this order, the sensor output increases when the color toner amount on the photosensitive drum increases, and the density is detected by the sensor output decreasing when the black toner amount increases. A sensor that determines the density by increasing or decreasing the scattered light can be referred to as a scattering-type optical density light sensor even if it has a configuration in which specularly reflected light enters the sensor light receiving unit.

  On the other hand, the specular reflection type optical density sensor is a type of sensor that detects the patch density by increasing or decreasing the amount of specularly reflected light from the image carrier, and a toner that scatters projection light on a mirror-like photosensitive drum. The sensor output decreases and the patch density is detected. As long as the sensor determines the density based on the increase / decrease of the specular reflection light, it can be said to be a specular reflection type optical density sensor even if the scattered light enters the sensor light receiving unit.

  By the way, as an electrophotographic photosensitive member used in an electrophotographic apparatus, a photosensitive member using an organic material is widely used because of advantages such as low cost and productivity. As the organic photoreceptor, a function-separated photoreceptor in which a charge generation layer containing an organic photoconductive dye or pigment and a charge transport layer containing a photoconductive polymer or a low molecular organic photoconductive material are laminated is the mainstream. When the charge transport layer is a surface layer, the layer has a structure of a molecular dispersion polymer in which an organic photoconductive substance is dispersed in a polymer, and therefore its mechanical strength depends on the polymer. With the high image quality and long life, the durability was not sufficient.

  On the other hand, it is known that it is effective to use a curable resin for the surface layer in order to increase the durability of the photoreceptor (for example, Patent Documents 3, 4, and 5).

  When a curable resin is used for the surface layer of the photoreceptor, mechanical strength is increased, it is difficult to scrape, scratches are less likely to occur, and the life is longer than a thermoplastic resin or the like. Further, when a curable resin is used for the surface layer of the photoreceptor, it is also known that it is useful to use an electron beam as a curing means from the viewpoint of durability against scratches and abrasions on the surface layer. (For example, refer to Patent Document 4).

  In general, when an electrophotographic photoreceptor is continuously used (also referred to as durability use or durability in this specification), the surface of the photoreceptor is subjected to electrical and mechanical stress, and therefore the number of durable sheets increases. The surface roughness value of the photoconductor changes every moment. In this case, the sensor output value when the specular reflection type optical density sensor used for γLUT correction is affected by the surface roughness of the photoconductor, the ratio of error to the measured value increases with durability. In particular, when only a small amount of toner is present on the photosensitive drum, it is greatly affected by the surface roughness of the photosensitive member, so that the influence on the γ correction at the low density portion of the toner becomes large and the error becomes more problematic.

  On the other hand, a photoconductor using the above curable resin with high durability is effective in suppressing the generation and growth of scratches caused by durability, but the generation and growth of scratches are not a little. Therefore, even if such a photoconductor is used, if it is used for a long period of time, the output value of the regular reflection type optical density sensor will fluctuate greatly, and the toner density cannot be accurately grasped, resulting in stable gradation. An image with excellent characteristics cannot be output.

On the other hand, a method for determining the toner density from the system aspect of the electrophotographic apparatus is also conceivable. For example, assuming the surface roughness value of the photoreceptor with respect to the number of durable sheets, calculating the toner correction coefficient value from the estimated value, and feeding back the correction coefficient value to the density value detected during the durability, the true toner density A method of obtaining a value can be considered. However, with this method, it is not possible to set an appropriate correction coefficient value for the surface roughness value of the photoreceptor that changes in various usage situations. In other words, because the surface roughness value of the photoconductor changes greatly due to disturbances such as paper type and environmental differences, the toner density cannot be uniquely determined only by the correction coefficient value for the number of durable sheets. For the wide range of users used below, satisfactory correction coefficient values could not be calculated, and accurate toner density could not be grasped.
JP 2003-195583 A JP 2003-091111 A Japanese Patent Laid-Open No. 07-72640 JP 2000-66425 A Japanese Patent Laid-Open No. 08-272197

  The present invention has been made under such circumstances, and a regular reflection toner density detection means for detecting the toner density on the peripheral surface of the electrophotographic photosensitive member, and a toner obtained from the regular reflection toner density detection means An electrophotographic apparatus having an image density control means for controlling an image density based on density information, wherein the toner density can be detected with high accuracy and high stability over a long period of time, and is stable in gradation. It is an object of the present invention to provide an electrophotographic apparatus capable of continuously outputting a high-definition image having excellent properties even after endurance. Another object of the present invention is to provide a process cartridge for use in the electrophotographic apparatus.

  Therefore, as a result of intensive studies, the present inventors have made it possible to increase the S / N ratio of the photodiode in the toner density detection means due to the surface shape of the photoconductor as much as possible, and the surface roughness of the photoconductor even after endurance. The electrophotographic apparatus having such a photoconductor is found by finding a configuration of a photoconductor that does not change significantly and can detect the toner density using a specular reflection type optical sensor well after durability. Has been found to be able to be solved, and the present invention has been completed.

  That is, the present invention is as follows.

(1) A cylindrical electrophotographic photosensitive member having a cylindrical support and a photosensitive layer provided on the cylindrical support, a charging means for charging the peripheral surface of the electrophotographic photosensitive member, and the charging An exposure means for forming an electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member by irradiating the peripheral surface of the electrophotographic photosensitive member charged by the means with exposure light, and the exposure means A developing means for forming a toner image on the peripheral surface of the electrophotographic photosensitive member by developing the electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member with toner, and the electrophotographic image formed by the developing means A transfer means for transferring the toner image on the peripheral surface of the photoreceptor to a transfer material, and a toner density on the peripheral surface of the electrophotographic photoreceptor after development by the developing means and before transfer by the transfer means. Regular reflection toner density detection for detection And the step, at least has an electrophotographic apparatus, the image density control means for controlling the image density by the toner density of the information obtained from the positive reflection toner concentration detecting means,
The surface layer of the electrophotographic photoreceptor contains a cured product obtained by curing and polymerizing a compound having a polymerizable functional group,
An electrophotographic apparatus, wherein the peripheral surface of the electrophotographic photosensitive member has a plurality of dimple-shaped recesses formed by a process of causing powder to collide with the surface of the surface layer.

(2) The incident angle θ ₂ [°] of the light from the light source of the regular reflection toner density detection means to the electrophotographic photosensitive member and the average θ ₁ [°] of the inclination angle of the dimple-shaped recess are θ ₁ <electrophotographic apparatus according to satisfy (1) the theta _2.

(3) The electrophotographic apparatus according to (2), wherein the θ ₂ [°] and θ ₁ [°] satisfy 2 × θ ₁ <θ ₂ .

  (4) The dimple-shaped recess of the light incident on the peripheral surface of the electrophotographic photosensitive member from the light source of the regular reflection toner density detecting means within the irradiation spot area on the peripheral surface of the electrophotographic photosensitive member. Among them, the total area of the dimple-shaped recesses having the longest diameter in the range of 1 to 50 μm and the depth in the range of 0.1 to 2.5 μm is based on the total area of the peripheral surface of the electrophotographic photosensitive member. The electrophotographic apparatus according to any one of (1) to (3), which is 60 area% or less.

  (5) Ten-point average roughness Rzjis (A) measured by sweeping in the circumferential direction of the peripheral surface of the electrophotographic photosensitive member is 0.5 to 2.5 μm, and a bus on the peripheral surface of the electrophotographic photosensitive member The ten-point average roughness Rzjis (B) measured by sweeping in the direction is 0.5 to 2.5 μm, and the average interval RSm of irregularities measured by sweeping in the circumferential direction of the peripheral surface of the electrophotographic photosensitive member ( C) is 10 to 90 μm, the average interval RSm (D) of the irregularities measured by sweeping in the direction of the generatrix of the peripheral surface of the electrophotographic photosensitive member is 10 to 90 μm, and the average interval RSm (D) of the irregularities The electrophotographic apparatus according to any one of (1) to (4), wherein a ratio value (D / C) of the unevenness to the average interval RSm (C) is 0.5 to 1.5.

  (6) The maximum peak height Rp (F) of the peripheral surface of the electrophotographic photosensitive member is 0.6 μm or less, and the maximum peak height Rp of the maximum valley depth Rv (E) of the peripheral surface of the electrophotographic photosensitive member. The electrophotographic apparatus according to any one of (1) to (5), wherein a ratio value (E / F) to (F) is 1.2 or more.

(7) The electrophotographic apparatus according to any one of (1) to (6), wherein a universal hardness value (HU) of a peripheral surface of the electrophotographic photosensitive member is 150 to 220 N / mm ² .

  (8) The electrophotographic apparatus according to any one of (1) to (7), wherein an elastic deformation rate of a peripheral surface of the electrophotographic photosensitive member is 45% or more.

  (9) The electrophotographic apparatus according to (8), wherein the elastic deformation rate of the peripheral surface of the electrophotographic photosensitive member is 50% or more.

  (10) The electrophotographic apparatus according to any one of (1) to (9), wherein an elastic deformation rate of a peripheral surface of the electrophotographic photosensitive member is 65% or less.

  (11) The cured product contained in the surface layer of the electrophotographic photoreceptor is at least one curable resin selected from the group consisting of an acrylic resin, a phenol resin, an epoxy resin, a silicone resin, and a urethane resin. The electrophotographic apparatus according to any one of (1) to (10).

  (12) The electrophotographic apparatus according to any one of (1) to (11), wherein the cured product contained in the surface layer of the electrophotographic photosensitive member is a curable resin having a charge transport function.

  (13) A cured product obtained by curing and polymerizing a hole transporting compound having a polymerizable functional group by one or both of heating and irradiation with the cured product contained in the surface layer of the electrophotographic photosensitive member. The electrophotographic apparatus according to any one of (1) to (12).

  (14) The electrophotographic apparatus according to (13), wherein the hole transporting compound having a polymerizable functional group is a hole transporting compound having two or more chain polymerizable functional groups in the same molecule.

  (15) The electrophotographic apparatus according to (13) or (14), wherein the radiation is an electron beam.

  (16) The electrophotographic apparatus according to any one of (15), wherein the treatment of causing the powder to collide with the surface of the surface layer is a dry blast treatment or a wet honing treatment.

  (17) A cleaning unit for cleaning the peripheral surface of the electrophotographic photosensitive member by removing toner remaining on the peripheral surface of the electrophotographic photosensitive member after the transfer by the transfer unit (1) to (16). The electrophotographic apparatus according to any one of the above.

  (18) The electrophotographic photosensitive member for an electrophotographic apparatus according to any one of (1) to (16), and the charging means and the developing means for the electrophotographic apparatus according to any one of (1) to (16) And a process cartridge which integrally supports at least one means selected from the group consisting of transfer means and is detachable from the electrophotographic apparatus main body according to any one of (1) to (16) .

  (19) At least selected from the group consisting of an electrophotographic photosensitive member for an electrophotographic apparatus according to (17) and a charging means, a developing means, a transfer means, and a cleaning means for an electrophotographic apparatus according to (17). A process cartridge which integrally supports one means and is detachable from the main body of the electrophotographic apparatus according to (17).

  According to the present invention, an electrophotographic apparatus capable of detecting toner density for a long period of time with high accuracy and high stability, and outputs a high-definition image having excellent gradation stability even after endurance. An electrophotographic apparatus that can continue can be provided. Further, according to the present invention, a process cartridge used for the electrophotographic apparatus can be provided.

  Hereinafter, the present invention will be described in detail.

  The electrophotographic apparatus of the present invention includes a cylindrical electrophotographic photosensitive member having a cylindrical support and a photosensitive layer provided on the cylindrical support, and charging for charging the peripheral surface of the electrophotographic photosensitive member. And an exposure means for forming an electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member by irradiating the peripheral surface of the electrophotographic photosensitive member charged by the charging means with exposure light, and the exposure Developing means for forming a toner image on the peripheral surface of the electrophotographic photosensitive member by developing the electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member with toner, and formed by the developing unit A transfer means for transferring the toner image on the peripheral surface of the electrophotographic photosensitive member to a transfer material, and the periphery of the electrophotographic photosensitive member after development by the developing means and before transfer by the transfer means Positive for detecting the toner density on the surface In the electrophotographic apparatus having at least the toner density detecting means and the image density controlling means for controlling the image density based on the toner density information obtained from the regular reflection toner density detecting means, the surface layer of the electrophotographic photosensitive member includes: A dimple-shaped recess comprising a cured product obtained by curing and polymerizing a compound having a polymerizable functional group, and a peripheral surface of the electrophotographic photosensitive member formed by a process of causing powder to collide with the surface of the surface layer It is characterized by having multiple.

  In general, when the surface layer of the photoreceptor is a layer formed by curing and polymerizing a compound having a polymerizable functional group, it is more resistant to scraping and scratches than a layer formed of a thermoplastic resin, before and after durability. The fluctuation range of the surface roughness state of the photoconductor can be reduced. If the density of toner is detected by a regular reflection type optical density sensor using such a photoconductor, it can be expected to some extent that the influence of the error can be reduced. However, an object of the present invention is to provide an electrophotographic apparatus capable of continuously outputting a high-definition image with high stability even after endurance. Here, the high-definition image means that the gradation of the low density portion is output as prescribed, and the high stability means that the high-definition image continues to be output without changing for a long period of time. means. In order to achieve such an object, it cannot be said that a photoreceptor having a surface layer formed by curing and polymerizing a compound having a polymerizable functional group is sufficient. In particular, it has not been possible to provide a satisfactory electrophotographic apparatus in terms of continuously outputting a good image with high stability.

  The present inventors have intensively studied and formed a dimple shape on a surface layer formed by curing and polymerizing a compound having a polymerizable functional group by a specific roughening means, and such a surface layer. When the photoconductor having the above is used, the SN ratio of the photodiode in the toner density detecting means can be increased as much as possible, and the fluctuation range of the surface roughness state of the photoconductor before and after the endurance can be reduced. It was confirmed that the fluctuation of the output value of the regular reflection type optical density sensor can be reduced, and that the toner density can be detected well after the endurance. Therefore, when such a photoconductor is used, an electrophotographic apparatus that continues to output a good image with high stability can be provided.

  The dimple shape shown in the present invention is a photoreceptor having a fine irregular shape on the peripheral surface of the organic electrophotographic photoreceptor. In particular, the peripheral surface is preferably processed so as to have more dents than the reference surface before roughening. Concave portions exist as isolated as possible, and the uneven shape of the peripheral surface of the photoconductor has an appropriate roughness, an appropriate uneven interval, an appropriate ratio of the protruded portions to the recessed portions, and the recessed portions are not particularly continuous in a stripe shape, It is preferable that the concave portion is formed so as not to have directionality.

  The photoreceptor of the present invention has a cylindrical shape that can be used repeatedly in an electrophotographic apparatus, has a rotating shaft, and repeats an electrophotographic process such as charging, image exposure, development, transfer, and cleaning while rotating. Used while. The cleaning blade is usually arranged in parallel to the rotation axis of the photoconductor and is in contact with the surface layer of the photoconductor. Therefore, the circumferential direction means a direction perpendicular to the rotation axis, and is a direction in which the photosensitive member is repeatedly brought into contact with each process member.

  In the present invention, it is a requirement to use an organic photoreceptor. Organic photoreceptors are usually suitable for roughening their film thickness, elastic properties, etc. after film formation on the photoreceptor. By controlling the roughening conditions, the surface shape to be finally used Can be controlled in a wide range. In particular, a photoconductor having an elastic deformation rate measured from the surface of the photoconductor within the range of the present invention can give a particularly good surface shape.

  The surface roughening technique of the present invention is an effective technique for forming a photoreceptor having excellent durability characteristics. In particular, a photoconductor having a high elastic deformation rate is excellent in durability, and even when used for a long period of time, there is little change in the initial surface shape and tends to maintain the shape. It is important to optimally control the surface shape of such a photoreceptor from the initial stage.

  Particularly preferred values for the elastic deformation rate and universal hardness value (HU) shown in the present invention are in the ranges shown below. The elastic deformation rate and HU were measured from the top surface of the photoreceptor before roughening.

  Here, the universal hardness value (HU) and the elastic deformation rate are the microhardness measuring device Fischer in which continuous hardness is obtained by continuously applying a load to the indenter and directly reading the indentation depth under the load. It can be measured using a scope H100V (Fischer). As the indenter, a Vickers quadrangular pyramid diamond indenter having a facing angle of 136 ° can be used. Specifically, measurement is performed in stages (273 points with a holding time of 0.1 s for each point) up to a final load of 6 mN.

  An outline of the output chart of the Fischerscope H100V (Fischer) is shown in FIG.

  In the figure, the vertical axis represents the load F (mN), and the horizontal axis represents the indentation depth h (μm). That is, this figure shows the result when the load is increased stepwise and the load is applied up to 6 mN, and thereafter the load is decreased stepwise similarly.

  In the present invention, the universal hardness value (hereinafter also referred to as HU) can be obtained by the following formula (1) from the indentation depth under the same load when the final load is 6 mN.

  The elastic deformation rate can be obtained from the work (energy) performed by the indenter on the membrane, that is, the change in energy due to the increase or decrease of the load on the membrane of the indenter, and specifically obtained from the following formula (2). it can.

  In the above formula, the total work Wt (nJ) indicates the area surrounded by A-B-D-A in FIG. 3, and the elastic deformation work We (nJ) is the area surrounded by C-B-D-C. Is shown.

  In the present invention, the elastic deformation ratio We% is preferably 45% or more, more preferably 50% or more, and preferably 65% or less. When the elastic deformation rate of the photosensitive member peripheral surface is less than 45%, the change in the surface shape after repeated use becomes large, and even if the surface is properly roughened, the surface shape cannot be maintained long, and the effect of the surface roughening lasts long. No longer. In other words, due to durability, the fluctuation range of the surface roughness state of the photoconductor becomes large, the fluctuation of the output value of the regular reflection type optical density sensor becomes large, and it is difficult to detect the toner density well after durability. It becomes. If it exceeds 65%, paper dust and toner are likely to be caught between the electrophotographic photosensitive member and the abutting member such as a charging member or a cleaning member for long-term durability, and by rubbing the surface of the electrophotographic photosensitive member, The surface of the photographic photosensitive member is likely to be damaged, and as a result, the fluctuation range of the surface roughness state of the photosensitive member becomes large, the fluctuation of the output value of the regular reflection type optical density sensor becomes large, and after the endurance It becomes difficult to detect the toner density satisfactorily.

  In the region where the elastic deformation ratio We% is 45% or more and less than 65%, on the contrary, the change in the surface shape after repeated use becomes small, and the roughening of the present invention becomes more effective. Here, when the surface layer is a layer containing a compound obtained by curing and polymerizing a compound having a polymerizable functional group, the value of the elastic deformation rate is approximately 45% or more.

In the present invention, the universal hardness value (HU) of the peripheral surface of the photoreceptor is preferably in the range of 150 to 220 N / mm ² .

When HU exceeds 220 N / mm ² , the amount of elastic deformation on the peripheral surface of the photoconductor becomes small. Therefore, during the endurance, a large pressure is locally applied to the photoconductor peripheral surface, and the photoconductor is likely to be deeply damaged. Further, sudden scratches are likely to enter the peripheral surface of the photoreceptor. For this reason, the output value of the regular reflection type optical density sensor is affected, and it becomes difficult to satisfactorily detect the toner density after endurance.

When HU is less than 150 N / mm ² , the amount of plastic deformation on the peripheral surface of the photoconductor is large, so that it is easy to be scraped and scratched. Again, it is difficult to detect the toner density well after durability. It becomes.

  In the present invention, in order to form the above-mentioned dimple shape on the surface layer, a process of making the powder collide with the surface is performed. As the treatment for causing the powder to collide with the surface, a dry blast method and a wet honing method are preferable. Further, it is more preferable to use a dry blasting method because an electrophotographic photosensitive member sensitive to humidity conditions can be roughened without contacting with a solvent such as water.

  As a method of blasting, there are a method of injecting using compressed air, a method of injecting using a motor as power, etc., but it is possible to precisely control the roughening of the photoconductor and in terms of simplicity of equipment. A method using compressed air is preferred.

  Examples of the material of the abrasive used for blasting include ceramic systems such as aluminum oxide, zirconia, silicon carbide, and glass, metal systems such as stainless steel, iron, and zinc, and resin systems such as polyamide, polycarbonate, epoxy, and polyester. In particular, glass, aluminum oxide, and zirconia are preferable from the viewpoint of roughening efficiency and cost.

  An example of the blasting apparatus used in the present invention is shown in FIG. The abrasive stored in the container (not shown) is guided to the nozzle through the path 2-4, and is jetted from the jet nozzle 2-1 using the compressed air introduced through the path 2-3. It collides with the photoconductor 2-7 supported by 2-6 and rotating. 2-5 is a blast abrasive grain.

  At this time, the distance between the nozzle and the work is determined by adjusting the nozzle fixing jig and arm 2-2 and 2-9. The nozzle normally performs the roughening process while moving in the direction of the rotation axis of the work, and the nozzle support 2-8 moves in the direction of the rotation axis of the work to perform the roughening process on the work without unevenness. be able to.

  At this time, it is necessary to adjust the shortest distance between the nozzle and the surface of the photoreceptor to an appropriate interval. If the distance is too close or too far, the processing efficiency may decrease, or the desired roughening may not be performed. It is necessary to adjust the pressure of the compressed air used for the power of injection to an appropriate pressure. Thus, a production method with good productivity can be established by roughening the organic photoreceptor after film formation.

  The surface shape or roughening of the present invention is independent of the surface shape of the conductive support underlying the photoreceptor. In particular, when the method for forming the organic photosensitive layer is a dip coating method, the surface on which the film is formed is often very smooth, and even if the base is roughened, the surface shape is not reflected.

  When the surface of the dimple-like surface of the present invention is formed by roughening by a process of colliding with powder, the organic photoreceptor is finally formed up to the layer to be used, and then roughened from the top surface layer of the photoreceptor. It is preferable to face.

  In the measurement method of the surface shape, in the present invention, the ten-point average roughness (Rzjis), the average interval of unevenness (RSm), the maximum peak height (Rp), and the maximum valley depth (Rv) are described in JIS-B0601-2001. This is measured according to the method.

  The measurement was performed using a surface roughness measuring instrument (trade name: Surfcorder SE3500 type, manufactured by Kosaka Laboratory Ltd.).

  The surface roughness of the photoreceptor to be roughened is preferably 0.5 to 2.5 μm in ten-point average roughness Rzjis in both cases measured by sweeping in the circumferential direction and the generatrix direction of the peripheral surface.

  When the surface roughness is less than 0.5 μm, the frictional force generated between the electrophotographic system and a contact member such as a cleaning blade on the circumferential surface of the photoreceptor increases. That is, the contact member is pressed against the photoconductor with high pressure. When endurance is performed in this state, when foreign matter such as lint mixed in the main body is sandwiched between the contact member and the photosensitive member, they are strongly pressed against the photosensitive member, and at the initial stage of durability, It will be a deep wound. In the middle of the durability period, the scratch condition is once stabilized, but the deep scratches in the initial stage of the durability grow in the middle to long term of the durability, and become deeper and longer. The surface shape before and after endurance changes greatly. As a result, when detecting the toner density after the endurance using the regular reflection type optical sensor, a certain part is adversely affected, and it becomes difficult to output a high-definition image with high stability.

  In addition, when the surface roughness value exceeds 2.5 μm, the same phenomenon occurs because the same foreign matter is likely to be caught as in the case where the surface roughness value (Rz value) is less than 0.5 μm. 5 micrometers-2.5 micrometers are preferable.

  The surface shape required in the present invention is a shape having a large number of isolated recesses as close to a circle as possible, which can be expressed as a so-called dimple shape. This dimple shape preferably has no directivity with respect to all directions on the circumferential surface of the photoreceptor.

  This is because, when the valley portions of the irregularities on the circumferential surface of the photoconductor are connected in a streak shape, the probability that the portions are combined and grow into scratches in the circumferential direction is increased.

  Accordingly, it can be derived from the surface roughness measurement data that Rzjis, RSm, etc. measured in all directions do not become greatly different depending on the measurement direction. Therefore, the ratio of the value of RSm (C) in the circumferential direction of the peripheral surface to the value of RSm (D) in the bus line direction (axial direction in which the photoconductor rotates) of the peripheral surface is preferably closer to 1.

  The average interval RSm of the unevenness is μm to 90 μm in both cases measured by sweeping in the circumferential direction and the busbar direction of the peripheral surface, and the ratio value of the RSm (D) in the busbar direction to the RSm (C) in the circumferential direction is It is preferable that (D / C) = 0.5 to 1.5.

  In particular, when the circumferential surface of the photosensitive member and the cleaning blade are in contact with each other with a speed difference, there is an optimal uneven spacing range, and when the RSm is less than 10 μm, the effect of roughening is reduced, and the photosensitive member circumferential surface in the electrophotographic system is reduced. The frictional force generated between the surface and the abutting member such as a cleaning blade is increased, and the above-described scratching and growth phenomenon on the peripheral surface of the photosensitive member appears. Even if the surface is larger than 90 μm, the same phenomenon occurs. Is likely to occur.

  For this reason, like the phenomenon that occurs in Rzjis, the surface state is not so suitable for high-definition density correction.

  Further, the surface shape of the present invention is intended to have a shape that has a concave portion more positively than a convex portion. When there are many convex shapes on the photoconductor and the height of the convex portion increases, the local resistance against the cleaning blade increases, and the edge portion of the cleaning blade is lost particularly when used for a long period of time, which becomes a trigger. The surface of the photoreceptor tends to be easily damaged.

  Therefore, in the present invention, the height of the convex portion is reduced, and the maximum peak height Rp (F) of the peripheral surface of the photoreceptor is preferably 0.6 μm or less, more preferably 0.4 μm or less. Further, it is preferable that the value (E / F) of the ratio of the maximum valley depth Rv (E) to the maximum peak height Rp (F) on the peripheral surface of the photoreceptor is 1.2 or more.

  The results of studying these dimple shapes in more detail will be described. The dimple shape was measured using a surface shape measurement system (Surface Explorer SX-520DR model, manufactured by Ryoka System Co., Ltd.).

  In the measurement, a drum sample was first placed on a work table, adjusted in tilt to be leveled, and the three-dimensional shape data of the peripheral surface of the photoreceptor was captured in the wave mode. At that time, the objective lens was observed by visual field observation of 100 μm × 100 μm using 50 × magnification. Next, the contour data of the peripheral surface was displayed using a particle analysis program in the data analysis software.

The hole analysis parameter for obtaining the area ratio of the dimples, the largest diameter upper limit: 50 [mu] m, maximum diameter lower limit: 1 [mu] m, depth limit: 2.5 [mu] m, the depth lower limit: 0.1 [mu] m, the volume limit: Set to 1 [mu] m ³ or more And observed. The observation was performed with a field of view of 100 μm × 100 μm, the total area was 10000 μm ² , and the area of the dimple portion was calculated by adding up the calculated values of the particle analysis software, and was calculated as (dimple total area / total area) × 100 (%). .

  The area ratio of dimples suitable for the photoreceptor of the present invention is preferably 60 area% or less.

  When the area ratio of these dimples exceeds the upper limit, the frictional force can be reduced, which is advantageous. However, the component that reflects the light from the light source on the surface of the photoreceptor in the regular reflection toner density detection means. On the other hand, the scattered component becomes large, and the amount of light received by the photodiode, which is the light receiving unit for detecting the density, becomes small. Therefore, the SN ratio becomes small, and the accuracy of density detection is lowered. In addition, when the dimple area ratio exceeds the upper limit, the dimple spacing is narrow, and the probability that the dimples are bonded together by durable use increases, and as a result, particles having a particle shape such as developer in the dimple It becomes easy to stay, and when it is pressed with a cleaning blade or the like, scratches are generated, and the scratches grow in the depth direction and circumferential direction, affecting the value of specular reflection optical density detection. Resulting in.

  Even in a system using a scattering type optical density sensor, if the upper limit is exceeded, scattering on the surface of the photoreceptor increases, the amount of reflected light returning to the sensor is too small, and the S / N ratio becomes small. The problem arises that it becomes difficult. In addition, since optical scattering occurs on the surface, when a latent image is formed with a laser, another adverse effect such as the latent image being easily disturbed is also exhibited.

In the present invention, the incident angle (angle formed with the incident surface) θ ₁ [°] of the light from the light source of the regular reflection toner density detecting means and the average θ ₂ of the inclination angle of the dimple-shaped concave portion of the photosensitive member. [°] preferably satisfies θ ₁ <θ ₂ , and more preferably satisfies 2θ ₁ <θ ₂ .

The above θ ₁ and θ ₂ will be described below with reference to FIG.

θ ₁ is an incident angle of the light emitted from the light source of the density detecting means to the photosensitive member. At this time, the light source and the photodiode are arranged in parallel to the generatrix direction of the support of the cylindrical photoconductor. θ ₂ is the inclination angle of the dimples on the circumferential surface of the photoreceptor, and is obtained as follows.

  First, at a portion irradiated with light emitted from the light source of the density detector within the surface of the photoconductor, several samples of about 5 mm square are arbitrarily cut out in the circumferential direction of the photoconductor. Among them, the cross section of one sample is observed with an SEM, and from among them, the longest diameter upper limit: 50 μm, the longest diameter lower limit: 1 μm, the depth upper limit: 2.5 μm, and the depth lower limit: 0.1 μm Several dimple parts are selected, and a cross-sectional photograph of the surface layer of the part is taken, and the following measurements are performed on the respective dimple parts from the cross-sectional photograph.

  A point indicating the Rvmax (maximum valley depth) of the dimple in the surface layer and two points on the edge portion forming the dimple are selected from the cross-sectional photograph. The angle formed by the line connecting the two points of the edge and the line connecting the point of the Rvmax and the edge is measured and averaged.

This operation was performed for several points in the cut sample and further for several samples cut in the surface of the photoconductor, and the average value of 20 or more in total was taken as θ _{2 of the} photoconductor. The relationship is shown below.

(Θ ₂₁ + θ ₂₂ + θ ₂₃ +... + Θ _2n ) / n = θ ₂
(N: integer of 20 or more, θ ₂ : dimple tilt angle)

In the present invention, this inclination angle θ ₂ is preferably larger than θ ₁ . If theta ₂ is, theta ₁ is less than, the regular reflection toner concentration detecting means, the light from the light source, the photosensitive member surface, to components for reflecting a component of scattering becomes remarkably larger tendency for density detection The amount of light received by the photodiode that is the light receiving portion is reduced. Therefore, the SN ratio becomes small, and the accuracy of density detection is lowered.

  In the present invention, isolated dimple-like irregularities having a shape close to a circle are shown. By having such a shape, it has an appropriate rough surface shape and is a rough surface having no directionality, so that the improvement effect of the present invention can be efficiently obtained for the reasons described before and after. .

  The surface layer of the photoreceptor having the surface shape of the present invention contains a cured product obtained by curing and polymerizing a compound having a polymerizable functional group. Such a surface layer has little surface wear when it is used endurance, and there is almost no change in the shape of the surface between the initial and endurance use, and the optimal surface shape formed initially is maintained. Even when the sheet is durable, it is possible to detect the toner density which is the same as the initial condition. Examples of the cured product include acrylic resin, phenol resin, epoxy resin, silicone resin, and urethane resin.

  In the present invention, the layer containing a cured product on the surface of the photoreceptor contains a monomer or oligomer having a polymerizable functional group in the coating material for producing the photoreceptor, and the film is heated and dried after film formation and drying. By providing a step of proceeding curing polymerization by irradiation or the like, a tough film-forming layer that is insoluble and infusible in a solvent or the like can be formed by three-dimensional curing polymerization.

  In the present invention, the cured product contained in the surface layer may be a curable resin having a charge transport function or a curable resin having no charge transport function, but has a charge transport function. A curable resin is preferred. That is, the best photosensitive layer in the present invention is one in which the surface is cured and polymerized by applying a coating containing a charge transporting material having a polymerizable functional group in the molecule, forming a film, and curing polymerizing. In order to further increase the curing strength of the surface layer, it is preferable that two or more polymerizable functional groups exist in the same molecule.

  As the layer structure of the photosensitive layer, a normal layer stack structure in which the charge generation layer / charge transport layer are stacked in this order from the conductive support side, and a reverse layer stack structure in which the charge transport layer / charge generation layer is stacked in this order from the conductive support side. Alternatively, any configuration of a single layer in which the charge generation material and the charge transport material are dispersed in the same layer can be employed.

  In a single photosensitive layer, generation and movement of photocarriers are performed in the same layer, and the photosensitive layer itself becomes a surface layer. On the other hand, the laminated photosensitive layer has a structure in which a charge generation layer for generating photocarriers and a charge transport layer for moving the generated carriers are laminated.

  Furthermore, in this invention, it is also possible to provide a protective layer on this.

  The most preferable layer structure is a normal layer structure in which the charge generation layer / charge transport layer are laminated in this order from the conductive support side.

  In this case, the charge transport layer is an electrophotographic photosensitive member that is an outermost surface layer containing a curable resin, or the charge transport layer is a laminated type of a non-curable first layer and a curable second layer. Any of the electrophotographic photoreceptors in which the curable second layer is the outermost surface layer is preferable.

  The surface layer in the present invention will be described in detail below.

  The surface layer of the present invention is formed by curing and polymerizing a compound having a polymerizable functional group. As the curing polymerization means, heat, light such as visible light and ultraviolet light, and radiation (electron beam, γ ray, etc.) can be used. In order to find the effects of the present invention more remarkably, the surface layer may be cured and polymerized with an electron beam. This is because the surface layer is cured and polymerized by irradiating a high-energy electron beam for a short time, without impairing the electrical characteristics (for example, increase in residual potential) on the electrophotographic characteristics. This is because a desired surface shape can be formed in the present invention.

  The procedure for forming the surface layer in the present invention is as follows.

  A coating solution that dissolves or contains a compound for the surface layer that can be cured and polymerized is applied by a dip coating method, spray coating method, curtain coating method, spin coating method, etc., and cured by the above curing polymerization means. Polymerize. The dip coating method is more preferable for efficient mass production of the photoreceptor.

  The structure of the photoconductor of the present invention is a single layer type in which both a charge generation material and a charge transport material are contained in the same layer on a conductive support, or a charge generation layer containing a charge generation material and a charge. Any of the stacked types in which the charge transport layers containing the transport material are stacked in this order or in the reverse order may be used. In the present invention, at least the surface layer of the photoreceptor only needs to contain a compound that can be cured and polymerized by heat, visible light, light such as ultraviolet rays, and radiation. However, the charge generation layer / charge transport layer or the charge transport layer is a non-curable first layer and a curable second layer in terms of characteristics as a photoreceptor, particularly electrical characteristics such as residual potential and durability. It is preferable to adopt a structure of a function-separated type photoreceptor in which layered layers are stacked in this order.

  In the present invention, the curing polymerization method of the compound to be cured and polymerized on the surface layer does not cause deterioration of the photoreceptor characteristics and does not increase the residual potential, and the fluctuation range of the surface roughness of the photoreceptor in durability can be further reduced. In view of the effect, an electron beam may be used as described above.

  In the case of electron beam irradiation, any type of accelerator such as a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type can be used. In the case of irradiating an electron beam, the acceleration voltage is preferably 250 KV or less, and optimally 150 KV or less, in order to develop the electrical characteristics and durability performance of the photoreceptor of the present invention. The irradiation dose is preferably in the range of 10 KGy to 1000 KGy, more preferably in the range of 30 KGy to 500 KGy. If the accelerating voltage exceeds the above, the electron beam irradiation damage tends to increase with respect to the photoreceptor characteristics. Further, when the irradiation dose is less than the above range, the curing polymerization tends to be insufficient, and when the dose is high, the photoreceptor characteristics are likely to deteriorate.

  The surface layer compounds that can be cured and polymerized include those having a polymerizable functional group in the molecule in terms of high reactivity, high reaction rate, and high hardness achieved after curing polymerization. Among them, compounds having an acrylic group, a methacryl group, and a styrene group are particularly preferable.

  In the present invention, the compound having a polymerizable functional group is roughly classified into a monomer and an oligomer by repeating the structural unit. A monomer means a polymer having a relatively small molecular weight without repeating a structural unit having a polymerizable functional group, and an oligomer means a polymer having a number of repeating structural units having a polymerizable functional group of about 2 to 20. . Further, a macromer having a polymerizable functional group only at the terminal of the polymer or oligomer can also be used as the curable compound for the surface layer of the present invention. Among them, in the present invention, it is preferable to use a compound having at least two polymerizable functional groups.

  In addition, the compound having a polymerizable functional group in the present invention is preferably a charge transport material in order to satisfy the charge transport function necessary for the surface layer. Among these, a hole transporting compound having a hole transporting function is more preferable. In particular, a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is more preferable.

  Examples of the compound having a polymerizable functional group in the present invention are shown below, but are not limited to these compounds.

  Next, the photosensitive layer of the electrophotographic photoreceptor in the present invention will be described in detail.

  The support for the electrophotographic photosensitive member may have any conductivity, for example, a metal or alloy such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, aluminum and copper Metal foil such as laminated on plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal with conductive layer applied alone or with binder resin, plastic Examples include film and paper.

  In the present invention, an undercoat layer (hereinafter also referred to as an intermediate layer) having a barrier function and an adhesive function can be provided on the conductive support.

  The undercoat layer is used to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect the photosensitive layer from electrical breakdown. Formed.

  Materials for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6 nylon, copolymer nylon, glue and gelatin Etc. can be used. These are dissolved in a solvent suitable for each and coated on a support. The film thickness at that time is preferably 0.1 to 2 μm.

  When the photoreceptor of the present invention is a function separation type photoreceptor, a charge generation layer and a charge transport layer are laminated. Examples of the charge generation material used for the charge generation layer include selenium-tellurium, pyrylium, thiapyrylium dyes, various central metals and crystal systems, specifically, crystal types such as α, β, γ, ε, and X types. Phthalocyanine-based compounds, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, quinocyanines, and JP-A No. 54-143645 Examples include amorphous silicone.

  In the case of a function-separated type photoreceptor, the charge generation layer is composed of the above charge generation material with a binder resin and a solvent in an amount of 0.3 to 4 times by mass, a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor, and the like. It is well dispersed by a method such as a roll mill, and formed by applying a dispersion and drying, or formed as a single composition film such as a vapor deposition film of the charge generation material. The film thickness is preferably 5 μm or less, and particularly preferably in the range of 0.1 to 2 μm.

  When using a binder resin, examples of the binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, trifluoroethylene, and polyvinyl alcohol. , Polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin and the like.

  Examples of the charge transport material used for the charge transport layer include suitable charge transport materials such as poly-N-vinylcarbazole, polystyryl anthracene and other high molecular compounds having a heterocyclic ring or a condensed polycyclic aromatic, pyrazoline, imidazole, and oxazole. , Triazole, carbazole and other heterocyclic compounds, triphenylalkane and other triarylalkane derivatives, triphenylamine and other triarylamine derivatives, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives and hydrazone derivatives And the like by applying and drying a solution dispersed / dissolved in a solvent together with an appropriate binder resin (the same binder resin described in the above-mentioned charge generation layer) can be used. can do. In this case, the ratio of the charge transport material to the binder resin is preferably selected in the range of 30 to 100, preferably 50 to 100, when the total mass of both is 100. When the amount of the charge transport material is less than that, the charge transport ability is lowered, and problems such as a decrease in sensitivity and an increase in residual potential occur. Also in this case, the film thickness of the photosensitive member is in the range of 5 to 30 μm. The film thickness of the photosensitive layer at this time is the charge generation layer, the charge transport layer, and / or the protective layer, or the charge generation layer, the charge. The transport layer is the total thickness of the non-curable first layer and the curable second layer stacked.

  In any case, the surface layer is generally formed by applying a polymerization / curing reaction after applying a solution containing the compound having a polymerizable functional group, but having the polymerizable functional group in advance. It is also possible to form a protective layer by using a solution obtained by reacting a solution containing a compound to obtain a cured product and then again dispersing or dissolving in a solvent. Examples of the method for applying these solutions include the dip coating method, the spray coating method, the curtain coating method, and the spin coating method as described in the description of the photosensitive layer. Of these methods, the dip coating method is more preferable from the viewpoint of efficiency / productivity. Moreover, vapor deposition, plasma, and other known film forming methods can be appropriately selected.

  Conductive particles may be mixed in the surface layer in the present invention.

  Examples of the conductive particles include metals, metal oxides, and carbon black. Examples of the metal include aluminum, zinc, copper, chromium, nickel, stainless steel, and silver, or those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and antimony-doped zirconium oxide. These can be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion.

  The average particle size of the conductive particles used in the present invention is preferably 0.3 μm or less, particularly preferably 0.1 μm or less, from the viewpoint of the transparency of the surface layer.

  In the present invention, among the conductive particles as described above, it is particularly preferable to use a metal oxide in terms of transparency.

The ratio of the conductive metal oxide particles in the surface layer is one of the factors that directly determine the resistance of the surface layer, and the resistance of the surface layer is in the range of 10 ¹⁰ to 10 ¹⁵ Ω · cm. Is preferred.

  The surface layer in the present invention can contain fluorine atom-containing resin particles.

  Examples of the fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylenepropylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and their co-polymers. It is preferable to appropriately select one or two or more types from the combination, but particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin. The molecular weight of the resin particles and the particle size of the particles can be appropriately selected and are not particularly limited.

  The ratio of the fluorine atom-containing resin particles in the surface layer is preferably 5 to 70% by mass, more preferably 10 to 60% by mass with respect to the total mass of the surface layer. When the proportion of the fluorine atom-containing resin particles is more than 70% by mass, the mechanical strength of the surface layer tends to be lowered, and when the proportion of the fluorine atom-containing resin particles is less than 5% by mass, the surface layer surface releasability, surface layer In some cases, the wear resistance and scratch resistance are not sufficient.

  In the present invention, additives such as radical scavengers and antioxidants may be added to the surface layer for the purpose of further improving dispersibility, binding properties and weather resistance.

  The thickness of the surface layer used in the present invention is preferably in the range of 0.2 to 10 μm, more preferably in the range of 0.5 to 6 μm.

  Next, the electrophotographic apparatus of the present invention for forming an image will be described. FIG. 1 shows an example of the electrophotographic apparatus of the present invention, but the present invention is not limited to this.

  The electrophotographic apparatus of the present invention includes, in addition to the above-described electrophotographic photosensitive member, a charging unit for charging the peripheral surface of the electrophotographic photosensitive member, and a peripheral surface of the electrophotographic photosensitive member charged by the charging unit. An exposure means for forming an electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member by irradiating with exposure light, and an electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member formed by the exposure means Developing means for forming a toner image on the peripheral surface of the electrophotographic photosensitive member by developing the toner, and transferring the toner image on the peripheral surface of the electrophotographic photosensitive member formed by the developing means to a transfer material And a regular reflection toner density detecting means for detecting the toner density on the peripheral surface of the electrophotographic photosensitive member after the development by the developing means and before the transfer by the transfer means, From regular reflection toner density detection means At least an image density control means for controlling the image density by the toner density of the information provided.

  More specifically, as shown in FIG. 1, the printer unit A and an image reading unit (image scanner) B mounted on the printer unit A are provided.

  The printer unit A includes a photosensitive member 1 that is an image carrier, a primary charger 2 that is a charging unit for charging the photosensitive member 1, and light that is applied to the charged photosensitive member 1 according to image information. An exposure device 3 that is an exposure means for forming an electrostatic latent image; a developing device 4 that is a development means for developing the electrostatic latent image formed on the photoreceptor 1 with toner; A transfer body 5 that is a transfer means for transferring a toner image carried by the photoreceptor 1 to the transfer material P, and a cleaning device that removes deposits on the surface of the photoreceptor 1 to which the toner image has been transferred from the surface of the photoreceptor 1. 6, a pre-exposure lamp 7 that erases the electrostatic history by irradiating light on the surface of the photoreceptor 1 from which deposits have been removed, and a transport belt that transports the transfer material P onto which the toner image has been transferred from the transfer body 5. 8 and the toner image of the transfer material P transported by the transport belt 8 is fixed on the transfer material P. And a fixing device 9 to be. Further, as will be described later, the electrophotographic apparatus of FIG. 1 includes the optical density detecting means shown in FIG. 2 and the image control means for controlling the image density based on the toner density information obtained from the optical density means. It is.

  As the photoreceptor 1, for example, an electrophotographic photoreceptor prepared by the method described in the examples is used.

  The primary charger 2 is a corona charger that charges the photoreceptor 1 in a non-contact manner. As the primary charger 2, a contact charger such as a conductive charging roller or a charging brush provided in contact with the photosensitive member 1 can be used.

  For example, as illustrated in FIG. 6, the exposure apparatus 3 includes a light emission signal generator 24 that generates a light emission signal of light to be irradiated based on an image signal read by the image reading unit B, and a light emission signal generator 24. A solid-state laser element 25 that generates laser light in response to a light emission signal, a collimator lens system 26 that defines an optical path width of the generated laser light, a rotary polygon mirror 22 that reflects the laser light having a defined optical path width, And an fθ lens group 23 that causes the photosensitive member 1 to scan the laser beam reflected by the rotary polygon mirror 22.

  The developing device 4 is composed of, for example, a plurality of developing devices and a rotor portion having these in the circumferential portion, and includes a developer having cyan toner, a developer having magenta toner, a developer having yellow toner, and Each developing device that accommodates each developer having black toner is transported to the developing position by the rotation of the rotor portion.

  In the drawing, two more special color developing machines can be introduced.

  The developing device is, for example, a two-component developing device as shown in FIG. 7, and a developing container 32 that stores a developer T composed of toner t and a carrier, and a developing device that is rotatably provided in an opening of the developing container 32. The developing sleeve 30 that carries the developer T contained in the container 32, the magnet roller 31 that is fixed inside the developing sleeve 30 and forms a plurality of magnetic poles at a plurality of predetermined positions, and the developing sleeve 30. A regulating blade 33 that regulates the layer thickness of the developer T (for example, a non-magnetic metal plate provided apart from the surface of the developing sleeve 30), a developing chamber R1 on the opening side in the developing container 32, and development A partition wall 36 partitioned into a stirring chamber R2 deeper than the chamber R1, transport screws 37 and 38 for transporting and stirring the developer T in each chamber, and a toner hopper containing toner to be supplied to the stirring chamber R2. A 4, and a supply port 35 of the hopper 34 to open and close toward the stirring chamber R2. The developing sleeve 30 is made of a nonmagnetic material such as aluminum or nonmagnetic stainless copper. The toner t is a color toner containing, for example, a hydrocarbon wax. The developing device can be appropriately selected according to the type of developer used.

  The transfer body 5 includes, for example, a roller-shaped transfer sheet 5c that carries the transfer material P, a transfer charger 5a that applies a voltage from the back surface of the transfer material P at the nip portion between the transfer sheet 5c and the photoreceptor 1, and a toner image. And a separation charger 5b for applying a voltage for separating the transfer material P onto which the toner is transferred from the transfer sheet 5c.

  The transfer sheet 5c is made of, for example, a polyethylene terephthalate resin film, and is stretched on the surface of the rotating drum, for example. The transfer body 5 is disposed so as to be in contact with and separated from the photoreceptor 1. The transfer body 5 is rotationally driven in the arrow direction (clockwise direction). In the present invention, a general material can be used as the transfer means such as the transfer body 5 and the charger.

  For example, as shown in FIG. 8, the cleaning device 6 adheres to a container-like casing 61 provided so as to open toward the photosensitive member 1 and an outer surface near the upper portion of the opening of the casing 61. A cleaning blade 62 made of urethane rubber or the like provided so as to contact the surface, a brush member 63 provided at a position where the opening of the casing 61 can rotate and slidably rub against the surface of the photoreceptor 1, A scraper 67 that abuts against the brush member 63 and collects the collected matter collected by the brush member 63 from the brush member 63, and a photosensitive member by a cleaning blade 62 provided at the lower end edge of the opening of the casing 61 from the casing 61. The squeeze sheet 64 for preventing the deposits removed from the surface of 1 and the collected matter from falling, and the deposits accommodated in the casing 61 The or collection, etc. and a screw 65 for conveying to the outside of the casing 61.

  The cleaning blade 62 is attached to the opening of the casing 61 by a support member. The cleaning blade 62 abuts one edge in the counter direction with respect to the rotational drive direction (a direction in the figure) of the image carrier 1. Further, the brush member 63 is in contact with the surface of the photoconductor 1 on the upstream side of the cleaning blade 62 in the rotation direction of the photoconductor 1.

  The brush member 63 includes, for example, a rotating shaft and a brush 66 that stands on the surface of the rotating shaft. The rotating shaft is made of metal and is grounded. The brush 66 is made of conductive fiber. The thickness of the fibers of the brush member 63 is 4 to 30 D / F, and the brush density is 10,000 to 400,000 pieces / square inch.

  The fixing device 9 includes, for example, a fixing roller 9a with a built-in heater, a pressure roller 9b provided to be biased relative to the fixing roller 9a, and a releasability such as silicone oil on the fixing roller 9a. Oil application means for applying oil. In the present invention, the oil applying means may not be provided.

  In addition to these, the printer unit A includes a paper feed cassette 10 that accommodates the transfer material P, paper feed rollers 11 and 12 that transport the transfer material P from the paper feed cassette 10 one by one, and toner image transfer. A registration roller 13 that conveys the transfer material P toward the transfer sheet 5 c in accordance with the timing, an adsorption roller 14 that attracts the transfer material P conveyed by the registration roller 13 to the transfer sheet 5 c, and the fixing device 9. A sheet discharge roller 15 for discharging the transfer material P to the outside of the apparatus and a tray 16 for storing the transfer material P discharged to the outside of the apparatus are provided.

  The image reading unit B includes a document table glass 20 on which the document G is placed, and an image reading unit 21 that reads an image of the document G placed on the document table glass 20. The image reading unit 21 includes a document irradiation lamp 21a that illuminates the document G with the document table glass 20 interposed therebetween, a short-focus lens array 21b that collects an image of the document G illuminated by the document irradiation lamp 21a, and a light collecting unit. And a CCD sensor 21c that reads the image of the original G and converts it into an image signal. The CCD sensor 21c is a full color sensor.

  Next, the operation of the electrophotographic apparatus according to the present invention will be described. The electrophotographic apparatus of the present invention can appropriately use known means and apparatuses relating to image formation, and is not limited to this embodiment.

  The photosensitive member 1 is driven to rotate in the direction of arrow a (counterclockwise) at a predetermined peripheral speed (process speed) around the central support shaft, and in the rotation process, the photosensitive member 1 is negatively charged in the present embodiment by the primary charger 2. A uniform corona charging process.

  Then, a laser beam modulated in response to an image signal output from the image reading unit B to the printer unit A side, which is output from the exposure device (laser scanning device) 3 to the uniformly charged surface of the photoreceptor 1. As a result of scanning exposure L, an electrostatic latent image of each color corresponding to the image information of the document G photoelectrically read by the image reading unit B is sequentially formed on the photoreceptor 1.

  The formation of the electrostatic latent image will be described. In the image reading unit B, the original G is placed on the upper surface of the original platen glass 20 with the surface to be copied facing down, and a not-shown original plate is placed thereon. Set. When the copy button (not shown) is pressed, the image reading unit 21 is moved from the home position on the left side to the right side of the platen glass 20 in FIG. Driven forward along the lower surface of the glass, when it reaches a predetermined reciprocating end point, it is driven backward and returned to the initial home position.

  In the forward driving process of the image reading unit 21, the downward image surface of the set original G on the platen glass 20 is sequentially illuminated and scanned from the left side to the right side by the document irradiation lamp 21a. The document surface reflected light is imaged and incident on the CCD sensor 21c by the short focus lens array 21b.

  The CCD sensor 21c includes a light receiving unit, a transfer unit, and an output unit (not shown). In the light receiving unit, an optical signal is changed to a charge signal and is sequentially transferred to the output unit in synchronization with a clock pulse. In the output section, the charge signal is converted into a voltage signal, amplified and reduced in impedance, and output. The analog signal thus obtained is converted into a digital signal by well-known image processing and output to the printer unit A. That is, the image information of the original G is photoelectrically read as a time-series electric digital pixel signal (image signal) by the image reading unit B.

  FIG. 9 shows a block diagram of an example of image processing. In the figure, the image signal output from the full color sensor 21c is input to the analog signal processing unit 71 and the gain and offset are adjusted, and then, for example, 8 bits ( 0 to 255 levels (256 gradations) of RGB digital signals, and the shading correction unit 73 uses a signal obtained by reading a reference white plate (not shown) for each color, and the sensor cell group of CCDs arranged in a line. In order to eliminate each sensitivity variation, a known shading correction is performed by optimizing the gain corresponding to each CCD sensor cell.

  The line delay unit 74 corrects a spatial shift included in the image signal output from the shading correction unit 73. This spatial shift is caused by the line sensors of the full color sensor 21c being arranged at a predetermined distance from each other in the sub-scanning direction. Specifically, the R (red) and G (green) color component signals are line-delayed in the sub-scanning direction with the B (blue) color component signal as a reference, and the phases of the three color component signals are synchronized.

  The input masking unit 75 converts the color space of the image signal output from the line delay unit 74 into an NTSC standard color space by matrix calculation. In other words, the color space of each color component signal output from the full color sensor 21c is determined by the spectral characteristics of the filter of each color component, but this is converted into the NTSC standard color space.

  The LOG conversion unit 76 is configured by a look-up table (LUT) including, for example, a ROM, and converts the RGB luminance signal output from the input masking unit 75 into a CMY density signal.

  The line delay memory 77 receives the image signal output from the LOG conversion unit 76 for a period (line delay) in which a black character determination unit (not shown) generates the control signals UCR, FILTER, SEN, and the like from the output of the input masking unit 75. Delay.

  The masking / UCR unit 78 extracts the black component signal K from the image signal output from the line delay memory 77, and further, YMCK performs a matrix operation for correcting the color turbidity of the recording color material of the printer unit on the signal. For example, an 8-bit color component image signal is output in the order of M, C, Y, and K for each reading operation of the reader unit. The matrix count used for matrix calculation is set by a CPU (not shown).

  Next, based on the obtained 8-bit color component image signal Data, processing for determining the recording rates Rn and Rt of dark dots and light dots is performed. For example, if the input gradation data Data is 100/255, the light dot recording rate Rt is determined to be 250/255, and the dark dot recording rate Rn is determined to be 40/255. The recording rate is shown as an absolute value with 255 being 100 percent.

  The γ correction unit 79 performs density correction on the image signal output from the masking / UCR unit 78 in order to match the image signal with the ideal gradation characteristics of the printer unit.

  The output filter (spatial filter processing unit) 80 performs edge enhancement or smoothing processing on the image signal output from the γ correction unit 79 in accordance with a control signal from the CPU.

  The LUT 81 is used to match the density of the original image and the density of the output image, and is composed of, for example, a RAM or the like, and its conversion table is set by the CPU.

  The pulse width modulator (PWM) 82 outputs a pulse signal having a pulse width corresponding to the level of the input image signal, and the pulse signal is input to a laser driver 83 that drives a semiconductor laser (laser light source).

  This electrophotographic apparatus is provided with a pattern generator (not shown) so that gradation patterns are registered so that a signal can be directly passed to the pulse width modulator 82.

  The exposure device 3 performs laser scanning exposure L on the surface of the photoreceptor 1 based on the image signal input from the image reading unit 21 to form an electrostatic latent image.

  When the exposure device 3 performs laser scanning exposure L on the surface of the photoreceptor 1, first, based on the image signal input from the image reading unit 21, the solid-state laser element 25 is lightened and darkened at a predetermined timing by the light emission signal generator 24 ( ON / OFF). Then, the laser light, which is an optical signal emitted from the solid-state laser element 25, is converted into a substantially parallel light beam by the collimator lens system 26, and the photoreceptor 1 is moved by the rotating polygon mirror 22 that rotates at high speed in the direction of arrow c. By scanning in the direction of arrow d (longitudinal direction), a laser spot is imaged on the surface of the photoreceptor 1 by the fθ lens group 23 and the reflection mirror.

  By such laser scanning, an exposure distribution corresponding to the scan is formed on the surface of the photoconductor 1, and further, by scrolling a predetermined amount perpendicular to the surface of the photoconductor 1 for each scan, the surface of the photoconductor 1 is obtained. An exposure distribution according to the image signal is obtained.

  That is, the uniformly charged surface (for example, charged to −700 V) of the photosensitive member 1 is scanned by the rotating polygon mirror 22 that rotates the light of the solid-state laser element 25 that emits ON / OFF light corresponding to the image signal at high speed. Thus, electrostatic latent images of respective colors corresponding to the scanning exposure pattern are sequentially formed on the surface of the photoreceptor 1.

  As shown in FIG. 2, in order to detect the amount of reflected light of a toner patch pattern, which will be described later, formed on the photoreceptor 1, an optical density detection unit using LED light sources 10a and 10b and photodiodes 11a and 11b. Two concentration sensors are provided in the same thrust direction. One is a scattering type optical sensor 40a used for toner density control in the developing device 4, and the other is a regular reflection type optical density sensor 40b used for γLUT correction.

  The scattering type optical sensor 40a is a type of sensor that detects the patch density by increasing or decreasing the amount of scattered light from the toner and the photoconductor, and the sensor output decreases due to the toner that scatters the projection light on the photoconductor. The patch density can be detected. By calculating this value in the main body, the degree of decrease in the toner density in the developing device 4 can be recognized, and replenishment control is performed from the toner replenishment tank so as to control it to be constant.

  As described above, in the electrophotographic apparatus of the present invention, gradation characteristics are controlled by γLUT correction by the regular reflection type optical density sensor 40b which is a regular reflection toner density detection means.

  This control achieves image stabilization by detecting the patch pattern density on the photoreceptor 1 and correcting the LUT 81 described above. Note that 200 lpi used for the gradation image is used as the patch pattern.

  FIG. 10 shows a processing circuit for processing a signal from a specular reflection type optical density sensor 40b composed of an LED light source 10b and a photodiode 11b facing the photosensitive member 1. The regular reflection type optical density sensor 40b used in this control is the regular reflection type optical density sensor 40b of the two optical density sensors arranged at the same thrust direction position facing the photosensitive member in the present embodiment. Only the regular reflection light from 1 is detected. Since this control corrects the γLUT, the effect clearly appears at the next image formation after patch formation.

  Near-infrared light from the photoreceptor 1 incident on the specular reflection type optical density sensor 40b is converted into an electric signal by the specular reflection type optical density sensor 40b, and the electric signal is 0 to 5V by the A / D conversion circuit 41. The output voltage is converted into a digital signal of 0 to 255 level, and the toner density is grasped by the density conversion circuit 42. Then, the image density is controlled using the image density control means based on the toner density information obtained from the regular reflection toner density detection means.

  FIG. 11 shows the relationship between the output of the regular reflection type optical density sensor 40b and the image density when the toner density on the photoconductor 1 is changed stepwise by the area gradation of each color.

  The output of the regular reflection type optical density sensor 40b when the toner is not attached to the photoreceptor 1 is set to 5V (ie, 255 level).

  As can be seen from FIG. 11, as the area coverage with toner increases and the image density increases, the output of the regular reflection optical density sensor 40b decreases. Here, if a table 42a for converting the sensor output signal dedicated to each color into a density signal is provided, the toner density signal can be read accurately for each color.

  Also, as shown in FIG. 11, when the photosensor output value becomes smaller, the image density reacts sensitively to small fluctuations in the photosensor output value in order to gain the image density and output the image density. End up. This is particularly noticeable in the low concentration region. In this case, good toner density detection cannot be performed, and even if the image density is controlled based on such a result, it is not sufficient to obtain sufficient gradation.

  However, according to the present invention, the variation in the surface roughness of the photoconductor after endurance use can be kept small, and the variation in the photosensor output value after endurance can be reduced. If the image density is originally controlled, a good image, particularly an image having excellent gradation can be stably obtained.

  The image density control means in the present invention is intended to stably maintain the color reproducibility achieved by the control system including the reader / printer. Therefore, the state immediately after the end of the control by the control system including the reader / printer is used as the target value. Set. The target value setting flow is shown in FIG. When the control of the system including both the reader / printer is finished, a patch pattern for each color of Y, M, C, and Bk is formed on the photoreceptor 1 and detected by the specular reflection type optical density sensor 40b.

  Here, the laser output of the patch uses 128 levels in the density signal for each color. At this time, the contents of the LUT 81 and the setting of the contrast potential are obtained by a control system including a reader / printer.

  The electrostatic latent image formed on the photoreceptor 1 is reversely developed by the developing device by the developing device 4 by the two-component magnetic brush method to be visualized as a first color toner image.

  In each developing device, the developer T in which the toner particles and the magnetic carrier particles are mixed is accommodated in the developing chamber R1 and the stirring chamber R2. Further, the developer T in the developing chamber R <b> 1 is transported in the longitudinal direction of the developing sleeve 30 by the rotational driving of the transport screw 37. The developer T in the stirring chamber R <b> 2 is transported in the longitudinal direction of the developing sleeve 30 by the rotational driving of the transport screw 38. The developer conveying direction by the conveying screw 38 is opposite to that by the conveying screw 37.

  The partition wall 36 is provided with openings (not shown) on the front side and the back side that are perpendicular to the paper surface, and the developer T transported by the transport screw 37 is fed from one of the openings to the transport screw. The developer T that has been transferred to the transfer screw 38 and transferred by the transfer screw 38 is transferred to the transfer screw 37 from the other one of the openings. The toner is charged to a polarity for developing the latent image by friction with the magnetic particles.

  The developing sleeve 30 is rotationally driven in the direction of arrow e (counterclockwise) to carry and transport the developer T mixed with toner and carrier to the developing unit C. The magnetic brush of the developer T carried on the developing sleeve 30 contacts the photosensitive member 1 that rotates in the direction of arrow a (clockwise) at the developing portion C, and the electrostatic latent image is developed at the developing portion C.

  A vibration bias voltage obtained by superimposing a DC voltage on an AC voltage is applied to the developing sleeve 30 by a power source (not shown). The dark portion potential (non-exposed portion potential) and the bright portion potential (exposed portion potential) of the electrostatic latent image are located between the maximum value and the minimum value of the vibration bias potential. As a result, an alternating electric field whose direction changes alternately is formed in the developing portion C. In this alternating electric field, the toner and the carrier vibrate violently, and the toner adheres to the bright portion of the surface of the photoreceptor 1 corresponding to the electrostatic latent image by shaking off the electrostatic constraint on the developing sleeve 30 and the carrier.

  The difference (maximum peak voltage) between the maximum value and the minimum value of the vibration bias voltage is preferably 1 to 5 kV (for example, a rectangular wave of 2 kV), and the frequency is preferably 1 to 10 kHz. The waveform of the vibration bias voltage is not limited to a rectangular wave, and may be a sine wave, a triangular wave, or the like.

  The DC voltage component is a value between the dark part potential and the bright part potential of the electrostatic latent image, but is an absolute value and closer to the dark part potential than the minimum bright part potential. However, it is preferable for preventing fog toner from adhering to the dark potential region. For example, with respect to the dark portion potential of −700 V, the light portion potential may be −200 V and the DC component of the developing bias may be −500 V. The minimum gap between the developing sleeve 30 and the photoreceptor 1 (the minimum gap position is in the developing portion C) is preferably 0.1 to 1 mm.

  Further, the amount of the developer T that is regulated by the regulation blade 33 and conveyed to the developing unit C is developed by the magnetic brush of the developer T formed by the magnetic field in the developing unit C by the developing magnetic pole S1 of the magnet roller 31. It is preferable that the height on the surface of the sleeve 30 is 1.2 to 5 times the minimum gap value between the developing sleeve 30 and the photoconductor 1 with the photoconductor 1 removed. . For example, if the minimum gap value is 500 μm (0.5 mm), it may be set to 700 μm.

  The developing magnetic pole S1 of the magnet roller 31 is disposed at a position facing the developing portion C, and a magnetic brush of developer T is formed by the developing magnetic field formed by the developing magnetic pole S1 on the developing portion C, and this magnetic brush is photosensitive. The dot distribution electrostatic latent image is developed in contact with the body 1. At this time, the toner adhering to the ears (brushes) of the magnetic carrier and the toner adhering to the sleeve surface instead of the ears are transferred to the exposed portion of the electrostatic latent image and developed.

The peak value of the strength (magnetic flux density in the direction perpendicular to the surface of the developing sleeve 30) of the developing magnetic field by the developing magnetic pole S1 on the surface of the developing sleeve 30 is 5 × 10 ⁻² T to ² × 10 ⁻¹ T. Is preferred. Further, the magnet roller 31 has N1, N2, N3, and S2 poles in addition to the developing magnetic pole S1.

  Here, a developing process for visualizing an electrostatic latent image on the surface of the photoreceptor 1 by a two-component magnetic brush method using a developing device and a circulation system of the developer T will be described.

  The developer T pumped up at the N2 pole by the rotation of the developing sleeve 30 is transported from the S2 pole to the N1 pole, and the layer thickness is regulated by the regulating blade 33 in the middle thereof to form a developer thin layer. Then, the developer T spiked in the magnetic field of the developing magnetic pole S1 develops the electrostatic latent image on the photoreceptor 1. Thereafter, the developer T on the developing sleeve 30 falls into the developing chamber R1 due to the repulsive magnetic field between the N3 pole and the N2 pole. The developer T that has fallen into the developing chamber R <b> 1 is stirred and conveyed by the conveying screw 37. Further, in such a circulation system, a new toner t corresponding to the consumed toner is dropped into the stirring chamber R2 through the supply port 35 and supplied.

  On the other hand, in synchronization with the formation of the toner image on the photosensitive member 1, a transfer material P such as paper stored in the paper feed cassette 10 is fed one by one by the paper feed roller 11 or 12, and the registration roller 13 is fed to the transfer body 5 at a predetermined timing, and the transfer material P is electrostatically attracted onto the transfer body 5 by the suction roller 14.

  The transfer material P electrostatically adsorbed on the transfer body 5 moves to a position facing the photoconductor 1 by the rotation of the transfer body 5 in the arrow direction (clockwise direction), and is transferred to the back side of the transfer material P by the transfer charger 5a. A charge having a reverse polarity to that of the toner is applied, and the toner image on the photoreceptor 1 is transferred to the surface side.

  After this transfer, the transfer residual toner remaining on the photosensitive member 1 is removed by the cleaning device 6, and then the surface of the photosensitive member 1 is further discharged by the pre-exposure lamp 7 to be used for forming the next toner image. Is done.

  Thereafter, the electrostatic latent image on the photoreceptor 1 is developed in the same manner, and the cyan toner a image, cyan toner b image, magenta toner image, yellow toner image, and black toner image formed on the photoreceptor 1 are transferred. A full color image is formed by being transferred onto the transfer material P on the transfer body 5 by the charger 5a.

  Then, the transfer material P is separated from the transfer body 5 by the separation charger 5 b, and the separated transfer material P is conveyed to the fixing device 9 through the conveyance belt 8. The transfer material P conveyed to the fixing device 9 is heated and pressed between the fixing roller 9a and the pressure roller 9b to which a small amount of oil is applied by the oil applying unit or the oil is not applied, A full color image is fixed on the surface of the transfer material P. Thereafter, the transfer material P is discharged onto the tray 16 by the paper discharge roller 15.

  Although not shown, for example, a photosensitive member, a charging unit for charging the photosensitive member, an exposure device, a developing device, a transfer unit provided corresponding to the photosensitive member, and a plurality of cleaning devices (as many as the number of types of toner) are provided. If an electrophotographic apparatus (a so-called tandem image forming apparatus) having a conveying unit that sequentially conveys a single transfer material to a transfer position of the transfer unit and a fixing device is used, each color toner image is directly applied to the transfer material. It becomes possible to transfer, and it is possible to form an image using two or more kinds of toners without using the transfer member 5 (intermediate transfer member) described above.

  In the present invention, as an electrophotographic apparatus, a plurality of constituent elements such as the above-described photosensitive member, developing means, and cleaning means are integrally coupled as an apparatus unit, and this unit is attached to the apparatus main body. You may comprise in a detachable cartridge. For example, the photosensitive member 1 and the cleaning device 6 may be integrated into one device unit, and may be detachable using a guide member such as a rail of the device body. At this time, the apparatus unit may be configured to be accompanied by a charging unit and / or a developing unit.

  The means necessary for performing a normal electrophotographic process, such as the exposure means, the developing means, and the transfer means in the present invention, are not limited at all, and the electrophotography in the cleaner-less system excluding the cleaning means due to the apparatus configuration. It is also possible to use components of the apparatus.

  The present invention is configured as an electrophotographic apparatus provided with the above-described photoreceptor and charging means, and is used not only for an electrophotographic copying machine but also for electronic devices such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making It can also be widely used in photographic application fields.

  The present invention can also be configured by a facsimile having a receiving means for receiving image information from a remote terminal.

  Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
(Photoreceptor manufacturing method)
The photoreceptor 1 shown in FIG. 1 of the present invention was prepared as follows. First, an aluminum cylinder (alloy of JIS A3003 aluminum) having a length of 370 mm, an outer diameter of 84 mm, and a thickness of 3 mm was prepared by cutting. When the surface roughness of this cylinder was measured in the circumferential direction, it was Rzjis = 0.08 μm. This cylinder is subjected to ultrasonic cleaning in pure water containing a detergent (trade name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.), followed by a detergent washing step, followed by ultrasonic cleaning in pure water. And degreased.

  Next, 60 parts by mass of titanium oxide powder (trade name: Kronos ECT-62, manufactured by Titanium Industry Co., Ltd.) having a coating film of tin oxide doped with antimony, titanium oxide powder (trade name: titone SR-) 1T, Sakai Chemical Co., Ltd.) 60 parts by mass, resol type phenol resin (trade name: Phenolite J-325, Dainippon Ink & Chemicals, Inc., solid content 70%) 70 parts by mass, 2-methoxy- A solution composed of 50 parts by mass of 1-propanol and 50 parts by mass of methanol was dispersed with a ball mill for about 20 hours. The average particle size of the filler contained in this dispersion was 0.25 μm.

  The dispersion prepared in this manner was applied on the aluminum cylinder by the dipping method, and was heated and dried for 48 minutes in a hot air drier adjusted to 150 ° C. to form a conductive layer having a thickness of 15 μm. .

  Next, 10 parts by mass of a copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) and 30 parts by mass of a methoxymethylated nylon resin (trade name: Toresin EF30T, manufactured by Teikoku Chemical Industry Co., Ltd.) were added to methanol 500 A solution dissolved in a mixed solution of parts by mass and 250 parts by mass of butanol is dip-coated on the conductive layer, put in a hot air drier adjusted to 100 ° C. for 22 minutes, dried by heating, and a film thickness of 0. A subbing layer of 45 μm was formed.

  Next, 4 parts by mass of a hydroxygallium phthalocyanine pigment having strong peaks at 7.4 ° and 28.2 ° with a Bragg angle of 2θ ± 0.2 ° in a CuKa line diffraction spectrum, a polyvinyl butyral resin (trade name: ESREC BX-1) , Manufactured by Sekisui Chemical Co., Ltd.) and a mixed solution consisting of 90 parts by mass of cyclohexanone was dispersed in a sand mill for 10 hours using glass beads having a diameter of 1 mm, and then 110 parts by mass of ethyl acetate was added for the charge generation layer. A coating solution was prepared. This coating solution was dip-coated on the undercoat layer, put into a hot air dryer adjusted to 80 ° C. for 22 minutes, and dried by heating to form a charge generation layer having a thickness of 0.17 μm.

  Next, 35 parts by mass of a triarylamine compound represented by the following structural formula (11)

And a coating for a charge transport layer prepared by dissolving 50 parts by mass of bisphenol Z-type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) in 320 parts by mass of monochlorobenzene and 50 parts by mass of dimethoxymethane The solution was dip-coated on the charge generation layer, placed in a hot air dryer adjusted to 100 ° C. for 40 minutes, and dried by heating to form a first charge transport layer having a thickness of 20 μm.

Next, after dissolving 0.45 part by mass of fluorine atom-containing resin as a dispersant in 35 parts by mass of 1,1,2,2,3,3,4-heptafluorocyclopentane and 35 parts by mass of 1-propanol, As a lubricant, 9 parts by mass of the same tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was added, and a high-pressure disperser (trade name: Microfluidizer M-110EH, US Microfluidics) 3) at a pressure of 59 MPa (600 kgf / cm ² ) and uniformly dispersed. This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion. Thereafter, 21 parts by mass of a hole transporting compound represented by the following structural formula (12)

Was added to the lubricant dispersion and subjected to pressure filtration with a PTFE 5 μm membrane filter to prepare a second charge transport layer coating solution as a curable surface layer. Using this coating solution, a second charge transport layer was applied as a curable surface layer on the first charge transport layer by a dip coating method.

Thereafter, an electron beam was irradiated in nitrogen under the conditions of an acceleration voltage of 150 kV and a dose of 1.5 × 10 ⁴ Gy. Subsequently, a heat treatment was performed for 90 seconds under the condition that the temperature of the photoconductor was 120 ° C. The oxygen concentration at this time was 10 ppm. Further, the photoconductor was heat-treated in a hot air dryer adjusted to 100 ° C. in the atmosphere for 20 minutes to form a second charge transport layer having a thickness of 6 μm.

  Similarly, two drum samples are prepared in the same manner as described above, one of which is for measuring the elastic modulus and universal hardness, and the other is for measuring the tilt angle of the dimple after the roughening treatment. Used as a sample.

  The hardness is measured by leaving the photoconductor in an environment of 23 ° C. and 50% humidity for 24 hours and then using the above-described microhardness measuring apparatus Fischerscope H100V (manufactured by Fischer). The value was calculated. The results are shown in Table 1.

  The elastic deformation rate is obtained by continuously applying hardness to the indenter and directly reading the indentation depth under the load. As the indenter, a Vickers quadrangular pyramid diamond indenter having a facing angle of 136 ° can be used. Specifically, it was measured stepwise up to a final load of 6 mN (273 points with a holding time of 0.1 S for each point).

(Roughening of the photoreceptor surface)
Using the dry blasting apparatus (produced by Fuji Seiki Co., Ltd.), which is a roughening means shown in FIG. 5, the surface of the photoreceptor prepared as described above was blasted under the following conditions.

Abrasive abrasive grains: spherical glass beads having an average particle size of 30 μm (trade name: UB-01L, manufactured by Union Co., Ltd.) was used. Air spraying pressure: 0.34 MPa (3.5 kgf / cm ² ), blast gun moving speed: 430 mm / min, work (photoconductor) rotation speed: 288 rpm, distance between blast gun discharge port and photoconductor: 100 mm, abrasive discharge Angle: 90 °, abrasive grain supply amount: 200 g / min, number of blasts: one way × 2 times, and abrasive material remaining on the surface of the photoreceptor was removed by blowing compressed air.

  When the surface shape of the outermost surface layer of this electrophotographic photosensitive member was measured, the values shown in Table 1 were obtained. The measurement was performed using a surface roughness measuring device (trade name: Surfcorder SE3500 type, manufactured by Kosaka Laboratory Ltd.). The measurement of Rzjis and RSm in the circumferential direction of the photoconductor was performed using the circumferential roughness measuring device for the above-mentioned apparatus. Measurement conditions were as follows: measurement length: 0.4 mm, measurement speed: 0.1 mm / s. The baseline level setting value for noise cut at the time of RSm measurement was measured at level setting = 10%.

  In the present invention, ten-point average roughness (Rzjis), average interval of unevenness (RSm), maximum peak height (Rp), and maximum valley depth (Rv) were measured according to the method described in JIS-B0601-2001. Say.

Further, the area ratio of dimple per 10000 μm ² of the surface layer of this photoreceptor was measured using the above-described surface shape measurement system (Surface Explorer SX-520DR type machine, manufactured by Ryoka System Co., Ltd.). Calculated.

  Further, using an extra drum sample, the inclination angle of the dimple after the surface roughening treatment of the electrophotographic photosensitive member was measured. In this measurement, since a cross-sectional photograph of the photosensitive layer is taken with an SEM and actually measured, it is necessary to destroy the photoconductor. Therefore, one extra sample was prepared.

  First, 8 samples of about 5 mm square are arbitrarily cut out in the circumferential direction in which light from the light source of the density detection sensor is irradiated within the surface of the photoreceptor. Among them, a cross section of one sample is observed with an SEM, and three dimple portions are arbitrarily selected from among them, and a point of Rvmax (maximum valley depth) of the dimple is searched at each location. Next, the point of the edge part of the dimple is specified, the Rvmax point and the two points of the edge are connected by a line, the line connecting the two points of the edge, and the line connecting the point of the Rvmax and the edge, Measure the angle formed. When there was no edge disturbance in one dimple, it was averaged to obtain the inclination of the place. When one is disturbed, the other is the tilt angle of the place, and when both are disturbed, the place is not measured and is not counted as a measurement point. This operation was continuously performed, and the tilt angles of a total of 24 dimples were measured and averaged to obtain the tilt angle of the dimple of the drum sample. Table 1 shows the results.

  The electrophotographic copying machine (trade name: iR C6800, manufactured by Canon Inc.) is modified so that negatively charged organic photoconductors can be mounted and there are no problems with cleaning and developing properties. Then, the image forming apparatus shown in FIG. 1 capable of continuously outputting a desired image was prepared, and the electrophotographic photosensitive member of this example was put in and placed in a normal temperature and humidity environment (22 ° C., 55% RH).

  The specular reflection type optical density sensor of the above-mentioned electrophotographic copying machine was previously adjusted in output by the following method. In the above-mentioned photoreceptor, the one that has not been coated on the aluminum cylinder surface is put into the electrophotographic copying machine, and the incident angle from the light source of the regular reflection type optical density sensor to the surface of the photoreceptor is Using a sensor of 70 degrees, GAIN adjustment was performed so that the output of the sensor was 5V. After making this adjustment, the above-mentioned photoconductor was inserted and the change in sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.8 V, the SN ratio was not so small, and the output value was sufficient to detect the toner density.

  Next, after creating a low density toner patch on the drum and adjusting the GAIN so that the output of the specular reflection optical density sensor in the initial state is 5 V, two full-color A4 test images are intermittently output in the same environment. Durability for 100,000 sheets, and after the endurance, read the toner density detection sensor output value when the same amount of toner is loaded on the photoreceptor, and output the image sample of the density gradation pattern in that state Then, visual evaluation was performed on the smoothness of gradation in the low density region on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 2>
After producing a photoconductor similar to the photoconductor of Example 1, the surface roughening conditions were changed, and a dimple having an inclination angle of 17 degrees was produced. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.7 V, the SN ratio was not so small, and the output value was sufficient to detect the toner density.

<Example 3>
After producing a photoconductor similar to the photoconductor of Example 1, the roughening treatment conditions were changed, and a dimple having an inclination angle of 63 degrees was produced. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.3 V, and the SN ratio was not so small, and was an output value sufficient to detect the toner density.

<Example 4>
After producing a photoconductor similar to the photoconductor of Example 1, the roughening treatment conditions were changed, and a dimple having an inclination angle of 45 degrees was produced. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.4 V, and the S / N ratio was not so small, and was an output value sufficient to detect the toner density.

<Example 5>
After producing a photoconductor similar to the photoconductor of Example 1, the roughening treatment conditions were changed, and a dimple having a tilt angle of 76 degrees was produced. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above-mentioned photoconductor is 2 V, and the SN ratio is not small, and is an output value that is possible for detecting the toner density.

<Example 6>
After creating a photoconductor similar to the photoconductor of Example 1, the surface roughening conditions were changed, and the dimple tilt angle was the same as 6 degrees, but the dimple area ratio was 20%. did. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.8 V, the SN ratio was not so small, and the output value was sufficient to detect the toner density.

<Example 7>
After producing a photoconductor similar to the photoconductor of Example 1, the surface roughening treatment conditions were changed to have the same dimple tilt angle as that of Example 6, but with a dimple area ratio of 40%. Created. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.7 V, the SN ratio was not so small, and the output value was sufficient to detect the toner density.

<Example 8>
After creating a photoconductor similar to the photoconductor of Example 1, the roughening treatment conditions were changed to have the same dimple tilt angle as that of Example 6, but with a dimple area ratio of 70%. Created. Thereafter, the above-mentioned photosensitive member was put into an electrophotographic copying machine in which the GAIN adjustment was performed so that the output of the specular reflection type optical density sensor was 5 V on the aluminum cylinder surface, and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.1 V, and the S / N ratio was not small and was an output value that was possible to detect the toner density.

<Example 9>
After creating a photoconductor similar to the photoconductor of Example 1, the surface roughening conditions were changed to be the same as the inclination angle of the dimples of Example 4, but from the light source of the toner density detection sensor to the surface of the photoconductor. In the electrophotographic copying machine using a toner density detection sensor having an incident angle of 60 degrees and adjusting the GAIN so that the output of the specular reflection type optical density sensor is 5 V on the aluminum cylinder surface, the above-mentioned photoreceptor is mounted. , And saw the change in sensor output value. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 2.3 V, and the SN ratio was not small, and was an output value that could be used for toner density detection.

<Comparative Example 1>
After producing a photoconductor similar to the photoconductor of Example 1, an electrophotographic copy in which the surface of the aluminum cylinder surface is GAIN adjusted so that the output of the specular reflection type optical density sensor is 5 V without performing roughening treatment. The above-mentioned photoconductor was put into the machine and the change in the sensor output value was observed. The results are shown in Table 1. The sensor reading value of the above photoreceptor was 4 V, the SN ratio was large, and the output value was sufficient to detect the toner density.

<Example 10>
In the production of the photoreceptor of Example 1, the first charge transport layer and the second charge transport layer which is the curable outermost layer were prepared in the same manner as in Example 1.

Next, in the roughening treatment of the Example 1, the air blowing pressure conditions from 0.34MPa (3.5kgf / cm ^2), except that the 0.19MPa (2.0kgf / cm ²⁾ Example 1 The surface roughening treatment was performed in the same manner as described above.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  Next, in the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the output of the regular reflection type optical density sensor in the initial state was adjusted with GAIN so as to be 5V, and then in a normal temperature and normal humidity environment ( At 22 ° C. and 55% RH), A4 test image full-color 2 sheets were endured 100000 endurance, and after endurance, the toner density detection sensor output value when the same amount of toner is loaded on the photoreceptor as the initial value In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed regarding the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 11>
In the production of the photoreceptor of Example 1, the first charge transport layer and the second charge transport layer which is the curable outermost layer were prepared in the same manner as in Example 1.

  Next, in the roughening treatment of Example 1, spherical glass beads of abrasive abrasive grains were used with an average particle size of 60 μm (trade name: UB-34L, manufactured by Union Co., Ltd.), and fine adjustment of air spray pressure was performed. A surface roughening treatment was carried out in the same manner as in Example 1 except that.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  Next, in the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the output of the regular reflection type optical density sensor in the initial state was adjusted with GAIN so as to be 5V, and then in a normal temperature and normal humidity environment ( At 22 ° C. and 55% RH), A4 test image full-color 2 sheets were endured 100000 endurance, and after endurance, the toner density detection sensor output value when the same amount of toner is loaded on the photoreceptor as the initial value In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed regarding the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 12>
In the production of the photoreceptor of Example 1, up to the first charge transport layer and the second charge transport layer which is a curable outermost surface layer were prepared in the same manner as in Example 1.

Next, in the roughening treatment of Example 11, the roughening treatment was performed in the same manner as in Example 1 except that the air spraying pressure condition was changed to 0.17 MPa (1.7 kgf / cm ² ).

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  Next, in the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the output of the regular reflection type optical density sensor in the initial state was adjusted with GAIN so as to be 5V, and then in a normal temperature and normal humidity environment ( At 22 ° C. and 55% RH), A4 test image full-color 2 sheets were endured 100000 endurance, and after endurance, the toner density detection sensor output value when the same amount of toner is loaded on the photoreceptor as the initial value In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed regarding the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 13>
In the production of the photoreceptor of Example 1, the first charge transport layer and the second charge transport layer which is the curable outermost layer were prepared in the same manner as in Example 1.

  Next, in the roughening treatment of Example 12, the spherical glass beads of abrasive abrasive grains were used in Example 12 except that an average particle size of 90 μm (trade name: UB-46L manufactured by Union Co., Ltd.) was used. The surface roughening treatment was performed in the same manner as above.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  Next, in the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the output of the regular reflection type optical density sensor in the initial state was adjusted with GAIN so as to be 5V, and then in a normal temperature and normal humidity environment ( At 22 ° C. and 55% RH), A4 test image full-color 2 sheets were endured 100000 endurance, and after endurance, the toner density detection sensor output value when the same amount of toner is loaded on the photoreceptor as the initial value In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed regarding the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 14>
In Example 1, after forming the first charge transport layer, no lubricant dispersion was used, and 30 parts by mass of the hole transporting compound of the above structural formula (12) and 10 parts by mass of the following structural formula (13) A second charge transport layer coating solution was prepared by dissolving in a mixed solvent of 50 parts by mass of chlorobenzene and 50 parts by mass of dichloromethane.

  This coating solution was coated on the first charge transport layer, and then irradiated with an electron beam in the same manner as in Example 1, but under the conditions of an acceleration voltage of 150 kV and a dose of 10 Mrad in nitrogen. Subsequently, a heat treatment was performed for 90 seconds under the condition that the temperature of the electrophotographic photosensitive member was 120 ° C. The oxygen concentration at this time was 10 ppm. Further, the electrophotographic photosensitive member was heated in an air dryer adjusted to 100 ° C. in the atmosphere for 20 minutes to form a second charge transport layer having a thickness of 2 μm. A roughening treatment was performed.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  In the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the GAIN was adjusted so that the output of the regular reflection optical density sensor in the initial state was 5 V. 55% RH), A4 test image 2 color full-color intermittently endured 100000 sheets, and after the endurance, read the output value of the toner density detection sensor when the same amount of toner is loaded on the photoconductor, In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed on the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 15>
In the production of the electrophotographic photosensitive member of Example 1, up to the first charge transport layer was produced in the same manner as in Example 1.

  The hole transporting compound represented by the structural formula (12) in Example 14 was changed to the hole transporting compound represented by the following structural formula (14), and a second charge transporting layer was formed on the first charge transporting layer using this coating solution. The layer was applied by dip coating. Thereafter, an electron beam was irradiated in nitrogen under conditions of an acceleration voltage of 150 kV and a dose of 10 Mrad. Subsequently, a heat treatment was performed for 90 seconds under the condition that the temperature of the electrophotographic photosensitive member was 120 ° C. The oxygen concentration at this time was 10 ppm. Further, the electrophotographic photosensitive member is heated in an air dryer adjusted to 100 ° C. in the atmosphere for 20 minutes to form a second charge transport layer having a film thickness of 6 μm. A roughening treatment was performed.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  In the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the GAIN was adjusted so that the output of the regular reflection optical density sensor in the initial state was 5 V. 55% RH), A4 test image 2 color full-color intermittently endured 100000 sheets, and after the endurance, read the output value of the toner density detection sensor when the same amount of toner is loaded on the photoconductor, In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed on the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Example 16>
In the production of the electrophotographic photosensitive member of Example 1, up to the first charge transport layer was produced in the same manner as in Example 1.

The compound represented by the structural formula (12) in Example 14 was replaced with a hole transporting compound represented by the following formula (15). In addition, 0.3 part by mass of fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 1,1,2,2,3,3,4-heptafluorocyclopentane. (Trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd.) 35 parts by mass and 1-propanol 35 parts by mass, and then a tetrafluoroethylene resin powder (trade name: Lubron L-2, Daikin Industries) 6 parts by mass was added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 600 kgf / cm ² with a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA). This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion. Thereafter, 27 parts by mass of the hole transporting compound represented by the formula (20) is added to the lubricant dispersion, pressure filtration is performed with a PTFE 5 μm membrane filter, and the photopolymerization of the structural formula (16) is started. The same amount of the agent was added to prepare a coating solution for the second charge transport layer.

This coating solution is dip-coated on the first charge transport layer and cured by irradiation with light at a light intensity of 500 mW / cm ² for 60 seconds using a metal halide lamp, and the electrophotographic photosensitive member is heated to 120 ° C. in the atmosphere. In the adjusted hot air drier, heat treatment was performed for 60 minutes to form a second charge transport layer having a thickness of 6 μm, and the same surface roughening treatment as in Example 1 was performed.
The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  Further, since the inclination angle of the dimples at this time is adjusted to be less than 35 degrees, the SN ratio of the sensor reading value of the toner density detecting means is small when mounted on the electrophotographic apparatus shown in the first embodiment. The output value was sufficient for toner density detection.

  In the same manner as in Example 1, a low-concentration toner patch was prepared on the drum, and the GAIN was adjusted so that the output of the regular reflection optical density sensor in the initial state was 5 V. 55% RH), A4 test image 2 color full-color intermittently endured 100000 sheets, and after the endurance, read the output value of the toner density detection sensor when the same amount of toner is loaded on the photoconductor, In this state, an image sample of the density gradation pattern was output, and visual evaluation was performed on the smoothness of gradation in the low density area on the gradation pattern, that is, density fluctuation. The results are shown in Table 2. As can be seen from Table 2, the detection sensor output value can be satisfactorily controlled with little change from the beginning, and the toner density is detected based on the sensor value, and information on the toner density is obtained. The gradation of the low density portion of the image in which the image density is controlled based on the above is equivalent to the initial state, and the gradation stability is excellent.

<Comparative Example 1 (continued)>
The electrophotographic photosensitive member produced in Example 1 was durable without being roughened. The evaluation results are shown in Table 2. The blade squealed from around the cleaning blade from around 5000 during the endurance, and the blade broke at 7000. When the blade was replaced, it was durable up to 50000 sheets and visually compared before and after the endurance. As a result, the surface state of the electrophotographic photosensitive member was changed and many deep scratches were observed. The fluctuation of the sensor output value after endurance was 2.8 V, and the output value was considerably small. The image density was controlled based on this sensor value. The obtained endurance image clearly lost the smoothness of the gradation pattern in the low density region.

<Comparative example 2>
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 using a photoconductor prepared without the second charge transport layer of Example 1 and having a first charge transport layer thickness of 25 (μm). A body was prepared and evaluated for durability without roughening. The evaluation results are shown in Table 2.

  When the durability was increased to 20000 sheets, the surface state of the electrophotographic photosensitive member was greatly roughened and many deep scratches were observed. The fluctuation of the sensor output value after endurance was 2.0 V, and the output value was very small. The image density was controlled based on this sensor value. The obtained post-durability image clearly lost the smoothness of the gradation pattern in the low-density region, and was a gritty image in the very thin low-density portion.

<Comparative Example 3>
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the dry blast treatment for the surface of the second charge transport layer was changed to the following surface treatment.

  First, an electrophotographic photosensitive member (up to the second charge transporting layer, hereinafter also referred to as “target object”) before surface treatment of the second charge transporting layer was mounted on a rotary polishing machine.

  Next, a brush with an abrasive (model name: TX # 320C-W, manufactured by State Kogyo Co., Ltd.) is brought into contact with the peripheral surface of the workpiece mounted on the rotary polishing machine at a brush pushing amount of 0.5 mm. Next, the peripheral surface of the object to be processed is polished in the circumferential direction by rotating the object to be processed at 5080 rpm and rotating the abrasive brush in the direction opposite to the rotation direction of the object to be processed at 3000 rpm for 120 seconds. did.

  The elastic modulus, universal hardness measurement, and surface roughness measurement of this photoconductor were performed in the same manner as in Example 1. The results are shown in Table 2.

  When the durability was increased to 30,000 sheets, the surface state of the electrophotographic photosensitive member was greatly roughened and many deep scratches were observed. The fluctuation of the sensor output value after endurance was 2.0 V, and the output value was very small. The image density was controlled based on this sensor value. The obtained post-durability image clearly lost the smoothness of the gradation pattern in the low-density region, and was a gritty image in the very thin low-density portion.

It is the schematic which shows the example of the electrophotographic apparatus of this invention. It is the schematic which shows arrangement | positioning of the optical density detection means in the electrophotographic apparatus of FIG. 1 of this invention. It is a measurement chart schematic diagram of microhardness measuring apparatus Fischerscope H100V (made by Fischer) used for the present invention. It is the schematic which shows the inclination-angle of the dimple in this invention. It is the schematic of the blast processing apparatus used for this invention. It is the schematic which shows the example of the exposure means of the electrophotographic apparatus of this invention. It is a schematic diagram showing an example of developing means of the electrophotographic apparatus of the present invention. It is the schematic which shows the example of the cleaning means which provided the brush member of the electrophotographic apparatus of this invention together. It is a block diagram which shows the example of the image processing performed with the electrophotographic apparatus of this invention. It is a flowchart which shows from the photo sensor of the electrophotographic apparatus of this invention to density | concentration conversion. It is a figure which shows the relationship between the photosensor output of the electrophotographic apparatus of this invention, and image density. It is a figure which shows the flowchart of target value setting.

Claims (19)

A cylindrical electrophotographic photosensitive member having a cylindrical support and a photosensitive layer provided on the cylindrical support, a charging means for charging the peripheral surface of the electrophotographic photosensitive member, and charging by the charging means An exposure means for forming an electrostatic latent image on the peripheral surface of the electrophotographic photosensitive member by irradiating the peripheral surface of the electrophotographic photosensitive member with exposure light, and the electrophotographic image formed by the exposure means A developing means for forming a toner image on the peripheral surface of the electrophotographic photosensitive member by developing the electrostatic latent image on the peripheral surface of the photosensitive member with toner, and the electrophotographic photosensitive member formed by the developing means. A transfer means for transferring the toner image on the peripheral surface to the transfer material; and for detecting the toner density on the peripheral surface of the electrophotographic photosensitive member after the development by the developing means and before the transfer by the transfer means Regular reflection toner density detection means In at least having the electrophotographic apparatus and the image density control means for controlling the image density by the toner density of the information obtained from the positive reflection toner concentration detecting means,
The surface layer of the electrophotographic photoreceptor contains a cured product obtained by curing and polymerizing a compound having a polymerizable functional group,
An electrophotographic apparatus, wherein the peripheral surface of the electrophotographic photosensitive member has a plurality of dimple-shaped recesses formed by a process of causing powder to collide with the surface of the surface layer. Incident angle θ ₂ of light from the light source of the regular reflection toner density detecting means to the electrophotographic photosensitive member
_2. The electrophotographic apparatus according to claim 1, wherein [°] and an average inclination angle θ ₁ [°] of the dimple-shaped recess satisfy θ ₁ <θ ₂ . The electrophotographic apparatus according to claim 2, wherein the θ ₂ [°] and θ ₁ [°] satisfy 2 × θ ₁ <θ ₂ .   The light incident on the peripheral surface of the electrophotographic photosensitive member from the light source of the regular reflection toner density detecting means is the largest in the dimple-shaped recess within the irradiation spot area on the peripheral surface of the electrophotographic photosensitive member. The total area of the dimple-shaped recesses having a major axis in the range of 1 to 50 μm and a depth in the range of 0.1 to 2.5 μm is 60 areas relative to the area of the entire peripheral surface of the electrophotographic photosensitive member. The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus is at most%.   The ten-point average roughness Rzjis (A) measured by sweeping in the circumferential direction of the peripheral surface of the electrophotographic photosensitive member is 0.5 to 2.5 μm, and swept in the generatrix direction of the peripheral surface of the electrophotographic photosensitive member. The ten-point average roughness Rzjis (B) measured in this manner is 0.5 to 2.5 μm, and the average interval RSm (C) of the unevenness measured by sweeping in the circumferential direction of the peripheral surface of the electrophotographic photosensitive member is The average interval RSm (D) of the irregularities measured by sweeping in the direction of the generatrix of the peripheral surface of the electrophotographic photosensitive member is 10 to 90 μm, and the irregularities of the average interval RSm (D) of the irregularities The electrophotographic apparatus according to any one of claims 1 to 4, wherein a ratio value (D / C) to an average interval RSm (C) of 0.5 to 1.5.   The maximum peak height Rp (F) of the peripheral surface of the electrophotographic photosensitive member is 0.6 μm or less, and the maximum peak height Rp (F) of the maximum valley depth Rv (E) of the peripheral surface of the electrophotographic photosensitive member. The electrophotographic apparatus according to claim 1, wherein a ratio value (E / F) with respect to is 1.2 or more. The electrophotographic apparatus according to claim 1, wherein a universal hardness value (HU) of a peripheral surface of the electrophotographic photosensitive member is 150 to 220 N / mm ² .   The electrophotographic apparatus according to claim 1, wherein an elastic deformation rate of a peripheral surface of the electrophotographic photosensitive member is 45% or more.   The electrophotographic apparatus according to claim 8, wherein an elastic deformation rate of a peripheral surface of the electrophotographic photosensitive member is 50% or more.   The electrophotographic apparatus according to claim 1, wherein an elastic deformation rate of a peripheral surface of the electrophotographic photosensitive member is 65% or less.   2. The cured product contained in the surface layer of the electrophotographic photoreceptor is at least one curable resin selected from the group consisting of an acrylic resin, a phenol resin, an epoxy resin, a silicone resin, and a urethane resin. The electrophotographic apparatus according to any one of 10 to 10.   The electrophotographic apparatus according to claim 1, wherein the cured product contained in the surface layer of the electrophotographic photosensitive member is a curable resin having a charge transport function.   The cured product contained in the surface layer of the electrophotographic photoreceptor is a cured product obtained by curing and polymerizing a hole transporting compound having a polymerizable functional group by one or both of heating and radiation irradiation. Item 15. The electrophotographic apparatus according to any one of Items 1 to 12.   The electrophotographic apparatus according to claim 13, wherein the hole transporting compound having a polymerizable functional group is a hole transporting compound having two or more chain polymerizable functional groups in the same molecule.   The electrophotographic apparatus according to claim 13, wherein the radiation is an electron beam.   The electrophotographic apparatus according to any one of claims 1 to 15, wherein the treatment for causing the powder to collide with the surface of the surface layer is a dry blast treatment or a wet honing treatment.   17. A cleaning unit for cleaning the peripheral surface of the electrophotographic photosensitive member by removing toner remaining on the peripheral surface of the electrophotographic photosensitive member after transfer by the transfer unit. Electrophotographic equipment.   The electrophotographic photosensitive member for an electrophotographic apparatus according to any one of claims 1 to 16, and the group consisting of charging means, developing means and transfer means for an electrophotographic apparatus according to any one of claims 1 to 16. 17. A process cartridge which integrally supports at least one selected means and is detachable from the electrophotographic apparatus main body according to claim 1.   18. An electrophotographic photosensitive member for an electrophotographic apparatus according to claim 17, and at least one means selected from the group consisting of charging means, developing means, transfer means and cleaning means for electrophotographic apparatus according to claim 17. 18. A process cartridge characterized in that the process cartridge is detachably attached to the main body of the electrophotographic apparatus according to claim 17.

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