JP2014071253A - Electrophotographic photoreceptor and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor configured to prevent an image defect such as image non-uniformity even if a surface layer thickness is reduced as the electrophotographic photoreceptor is used.SOLUTION: An electrophotographic photoreceptor 1 includes a cylindrical substrate 10, a photosensitive layer 11 including at least a photoconductive layer formed on the cylindrical substrate 10, and a surface layer 12 formed on the photosensitive layer 11. The surface layer 12 includes a detection area 12a for detecting a wear degree of the surface layer 12 due to the use of the electrophotographic photoreceptor 1. A ratio of thickness of the surface layer 12 in an area adjacent to the detection area 12a with respect to the surface layer 12 in the detection area 12a is 20-80%. In the electrophotographic photoreceptor 1, the wear degree of the surface 12 can be detected by the detection area 12a, thereby preventing image defect such as image non-uniformity.

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus including the same.

  Conventionally, an electrophotographic photosensitive member is manufactured by forming a photoconductive layer, a surface layer, and the like as a deposited film on the surface of a substrate such as a cylindrical shape as described in Patent Document 1, for example. As a method for forming a deposited film, a method (plasma CVD method) in which a decomposition product obtained by decomposing a source gas by high-frequency glow discharge is applied to a substrate is widely employed.

  However, such an electrophotographic photosensitive member has a problem in that the surface layer is worn with use to reduce the thickness of the electrophotographic photosensitive member to reduce the charging ability of the electrophotographic photosensitive member, resulting in image defects such as image unevenness. there were.

JP-A-63-129348

  The present invention has been made in view of the above problems, and even when the surface layer is thinned with the use of an electrophotographic photosensitive member, it is possible to prevent image defects such as image unevenness from occurring. An object is to provide an electrophotographic photoreceptor.

  The electrophotographic photosensitive member of the present invention includes an electrophotographic photosensitive member comprising a cylindrical substrate, a photosensitive layer including at least a photoconductive layer formed on the cylindrical substrate, and a surface layer formed on the photosensitive layer. The surface layer has a detection region for detecting the degree of wear of the surface layer due to the use of the electrophotographic photosensitive member, and the thickness of the surface layer in a region adjacent to the detection region The ratio of the thickness of the surface layer in the detection region with respect to is 20 to 80%.

  In addition, the electrophotographic photosensitive member of the present invention is characterized in that, in the above configuration, the size of the detection area is φ20 μm or more when viewed from the surface side of the surface layer.

  Furthermore, the electrophotographic photosensitive member of the present invention is characterized in that, in the above configuration, the size of the detection region is less than φ100 μm.

  The electrophotographic photosensitive member of the present invention is characterized in that, in the above configuration, the detection region is continuously arranged along a circumferential direction of the surface layer.

  Furthermore, the electrophotographic photosensitive member of the present invention has the above-described configuration, wherein the detection region has a plurality of types of detection regions, and the respective types with respect to the thickness of the surface layer in a region adjacent to each type of detection region The ratios of the thicknesses of the surface layers in the detection regions are different from each other.

In the electrophotographic photosensitive member of the present invention, in the above configuration, the surface layer has a charging region that is charged by a charging unit that applies a charge, and the detection region is the lengthwise direction of the cylindrical substrate. It is arranged in the charging area within 20 mm from both ends of the charging area.

  An image forming apparatus according to the present invention includes any one of the above electrophotographic photosensitive members.

  According to the electrophotographic photosensitive member of the present invention, an electron including a cylindrical substrate, a photosensitive layer including at least a photoconductive layer formed on the cylindrical substrate, and a surface layer formed on the photosensitive layer. In the photographic photoconductor, the surface layer has a detection region for detecting the degree of wear of the surface layer due to the use of the electrophotographic photoconductor, and the surface layer in a region adjacent to the detection region Since the ratio of the thickness of the surface layer in the detection area to the thickness of the film is 20 to 80%, even if the surface layer becomes thinner with use of the electrophotographic photosensitive member, image defects such as image unevenness occur. It is possible to realize an electrophotographic photosensitive member that can prevent this.

(A) is sectional drawing which shows an example of the electrophotographic photoreceptor of this invention. (B) is principal part sectional drawing of (a). It is a longitudinal cross-sectional view of a deposited film forming apparatus. 1 is a cross-sectional view of an image forming apparatus of the present invention. FIG. 6 is a development view showing a first modification of the electrophotographic photosensitive member shown in FIG. 1. FIG. 7 is a development view showing a second modification of the electrophotographic photosensitive member shown in FIG. 1. FIG. 7 is a development view showing a third modification of the electrophotographic photosensitive member shown in FIG. 1.

  Hereinafter, an example of an embodiment of an electrophotographic photosensitive member of the present invention and an image forming apparatus including the same will be described with reference to the drawings. The following examples illustrate the embodiments of the present invention, and the present invention is not limited to the examples of these embodiments.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor 1 shown in FIG. 1 has a photosensitive layer 11 in which a charge injection element layer 11 a and a photoconductive layer 11 b are sequentially formed on the outer peripheral surface of a cylindrical substrate 10. Layer 12 is applied.

The cylindrical substrate 10 serves as a support for the photosensitive layer 11 and is formed to have conductivity at least on the surface. The cylindrical substrate 10 is made of, for example, aluminum (Al), stainless steel (SUS), zinc (Zn), copper (Cu), iron (Fe), titanium (Ti), nickel (Ni), chromium (Cr), tantalum ( The whole is formed of a metal material such as Ta), tin (Sn), gold (Au), and silver (Ag), or an alloy material including these exemplified metal materials as having conductivity. The cylindrical substrate 10 is formed by coating a conductive film made of a transparent conductive material such as an exemplified metal material and ITO (Indium Tin Oxide) or SnO _{2 on} the surface of an insulator such as resin, glass or ceramics. It may be. Of the exemplified materials, it is most preferable to use an aluminum (Al) -based material as a material for forming the cylindrical substrate 10, and the entire cylindrical substrate 10 is formed of an aluminum (Al) -based material. Is preferred. In this case, the electrophotographic photosensitive member 1 can be manufactured at a low weight and at a low cost. In addition, when the charge injection blocking layer 11a and the photoconductive layer 11b are formed of an amorphous silicon (a-Si) -based material. The adhesion between these layers and the cylindrical substrate 10 is increased, and the reliability can be improved.

The charge injection blocking layer 11a is for blocking the injection of carriers (electrons) from the cylindrical substrate 10, and is made of, for example, an amorphous silicon (a-Si) material. The charge injection blocking layer 11a is formed, for example, as amorphous silicon (a-Si) containing boron (B), nitrogen (N), and oxygen (O) as dopants, and has a thickness of 2 μm to 10 μm. It is as follows.

The photoconductive layer 11b is for generating carriers by light irradiation such as a laser beam, for example, amorphous silicon (a-Si) based material and amorphous selenium, such as Se-Te or _As 2 Se ₃ (a-Se ) It is made of a material. However, the electrophotographic characteristics (for example, photoconductive characteristics, high-speed response, repeat stability, heat resistance or durability) and the surface layer 12 when the surface layer 12 is formed of an amorphous silicon (a-Si) -based material. In consideration of the consistency, the photoconductive layer 11b is made of amorphous silicon (a-Si) and amorphous silicon (a-Si) added with carbon (C), nitrogen (N), oxygen (O) and the like. A silicon (a-Si) -based material is preferably used, and in this example, boron (B) is contained as a dopant.

  The thickness of the photoconductive layer 11b may be set as appropriate according to the photoconductive material used and the desired electrophotographic characteristics, and the photoconductive layer 11b is formed using an amorphous silicon (a-Si) material. In this case, the thickness of the photoconductive layer 11b is, for example, 5 μm to 100 μm, preferably 10 μm to 80 μm.

The surface layer 12 is for protecting the surface of the photosensitive layer 11 and has high resistance to abrasion caused by rubbing in the image forming apparatus, for example, amorphous silicon carbide (a-SiC) or amorphous silicon nitride ( a-SiN) and other amorphous silicon (a-Si) -based materials and amorphous carbon (a-C). The surface layer 12 has a sufficiently wide optical band gap with respect to the irradiated light so that light such as laser light irradiated to the electrophotographic photosensitive member 1 is not absorbed. It has a resistance value (generally 10 ¹¹ Ω · cm or more) that can hold an electrostatic latent image in image formation.

  However, even if a material having high resistance to abrasion due to rubbing in the image forming apparatus is selected for the surface layer 12, it is inevitable that the surface layer 12 becomes thin due to abrasion due to rubbing.

The surface layer 12 of this example is formed to a thickness of about 1 μm, and has a resistance value of 10 ¹¹ Ω · cm or more as described above, and therefore can hold an electrostatic latent image in image formation. However, when the surface layer 12 is thinned by abrasion due to rubbing, the resistance value is naturally reduced and the charging ability is lowered. Therefore, image defects such as image unevenness occur.

  Therefore, a detection region 12a for detecting the degree of wear of the surface layer 12 due to the use of the electrophotographic photosensitive member 1 is arranged on the surface layer 12, and the surface layer 12 is thinned by abrasion due to rubbing in the image forming apparatus. Detecting that By receiving the detection result and replacing the electrophotographic photosensitive member 1 before image defects such as image unevenness occur, it is possible to prevent image defects such as image unevenness from occurring.

  The thickness of the surface layer 12 in the detection region 12a is set to 20 to 80% of the thickness of the surface layer 12 in the region adjacent to the detection region 12a. In other words, the ratio of the thickness of the surface layer 12 in the detection region 12a to the thickness of the surface layer 12 in the region adjacent to the detection region 12a is 20 to 80%.

From experience, it is known that the thickness of the surface layer 12 in the region adjacent to the detection region 12a and the thickness of the surface layer 12 in the detection region 12a, which are worn by rubbing in the image forming apparatus, are substantially equal. The thickness of the surface layer 12 in the detection region 12a is previously determined as the detection region 12a.
The thickness of the surface layer 12 in the detection region 12a is greater than the thickness of the surface layer 12 in the region adjacent to the detection region 12a. Also, it is always thinner by the initial setting. Therefore, due to abrasion caused by rubbing in the image forming apparatus, the surface layer 12 in the detection region 12a has a thickness of image defects such as image unevenness more than the thickness of the surface layer 12 in the region adjacent to the detection region 12a. Achieving a thickness that can be charged quickly. Therefore, when the electrophotographic photosensitive member 1 is used by being incorporated in an image forming apparatus, the image formed on the recording medium region corresponding to the detection region 12a is checked to make the electrophotographic photosensitive member 1 uneven. It is possible to replace the image defect before it occurs. Here, the method for confirming the image formed on the recording medium is exemplified. However, by confirming the density of the toner adhering to the surface layer 12 in the detection region 12a, the electrophotographic photosensitive member 1 is free from image defects such as image unevenness. It is also possible to replace it before it occurs.

  Here, the confirmation of the image and the confirmation of the toner density are, for example, when an image is formed in a region where an image is not originally formed or an image is not formed in a region where an image is originally formed. If the degree of chargeability is reduced, or if the toner adheres to the area where the toner is not originally attached, or if the toner does not adhere to the area where the toner is originally attached, the degree of adhesion, that is, the toner concentration. This means that the degree of decrease in charging ability is confirmed.

  The size of the detection region 12a is desirably φ20 μm or more when viewed from the surface side of the surface layer 12. When the size of the detection region 12a is less than φ20 μm, when the image formed on the recording medium is confirmed by visual observation or visual observation using a magnifying glass, it may be performed by an image recognition device. This is because the possibility of misrecognition increases.

  Further, the size of the detection region 12a is desirably less than φ100 μm when viewed from the surface side of the surface layer 12. When the size of the detection region 12a is φ100 μm or more, the image formed on the recording medium can be sufficiently recognized visually, so that an image is originally formed where the image should not be formed, This is because an image is originally not formed at a place where an image is formed, and print quality is deteriorated.

  The shape of the detection region 12a is not limited to a circular shape, and may be any shape such as a polygonal shape, a star shape, or an indefinite shape as long as the size is φ20 μm or more.

  The charge injection blocking layer 11a, the photoconductive layer 11b, and the surface layer 12 in the electrophotographic photosensitive member 1 are formed using, for example, the plasma CVD apparatus 2 shown in FIG.

(Plasma CVD equipment)
The plasma CVD apparatus 2 accommodates the support 3 in a vacuum reaction chamber 4 and further includes a rotating means 5, a source gas supply means 6 and an exhaust means 7.

  The support 3 is for supporting the cylindrical substrate 10. The support 3 is formed in a hollow shape having a flange portion 30 and is entirely formed of a conductive material similar to that of the cylindrical substrate 10 as a conductor. In the case of this example, the support 3 is formed to a length that can support the two cylindrical bases 10, and is detachable from the conductive support 31. Therefore, in the support 3, the two cylindrical substrates 10 can be taken in and out of the vacuum reaction chamber 4 without directly touching the surfaces of the two supported cylindrical substrates 10.

The conductive support 31 is made of the same conductive material as that of the cylindrical substrate 10 and is entirely formed as a conductor, and is insulated from the plate 42 described later at the center of the vacuum reaction chamber 4 (cylindrical electrode 40 described later). It is fixed via a material 32. A DC power supply 34 is connected to the conductive support 31 via a conductive plate 33. The operation of the DC power supply 34 is controlled by the control unit 35. The control unit 35 is configured to supply a pulsed DC voltage to the support 3 via the conductive support 31 by controlling the DC power supply 34.

  A heater 37 is accommodated inside the conductive support 31 via a ceramic pipe 36. The ceramic pipe 36 is for ensuring insulation and thermal conductivity. The heater 37 is for heating the cylindrical substrate 10. As the heater 37, for example, a nichrome wire or a cartridge heater can be used.

  Here, the temperature of the support 3 is monitored, for example, by a thermocouple (not shown) attached to the support 3 or the conductive support 31, and the heater 37 is turned on / off based on the monitoring result of the thermocouple. By turning off, the temperature of the cylindrical substrate 10 is maintained within a certain range selected from a target range, for example, 200 ° C. or more and 400 ° C. or less.

  The vacuum reaction chamber 4 is a space for forming a deposited film on the cylindrical substrate 10 and is defined by a cylindrical electrode 40 and a pair of plates 41 and 42.

  The cylindrical electrode 40 is formed in a cylindrical shape surrounding the support 3. The cylindrical electrode 40 is formed of a conductive material similar to that of the cylindrical substrate 10 and is hollow, and is joined to a pair of plates 41 and 42 via insulating members 43 and 44.

  The cylindrical electrode 40 is formed in such a size that the distance D1 between the cylindrical substrate 10 supported by the support 3 and the cylindrical electrode 40 is 10 mm or more and 100 mm or less. This is because when the distance D1 between the cylindrical substrate 10 and the cylindrical electrode 40 is smaller than 10 mm, workability cannot be sufficiently ensured when the cylindrical substrate 10 is taken in and out of the vacuum reaction chamber 4, etc. When it becomes difficult to obtain a stable discharge between the substrate 10 and the cylindrical electrode 40, conversely, when the distance D1 between the cylindrical substrate 10 and the cylindrical electrode 40 is larger than 100 mm, the plasma CVD apparatus 2 This is because the productivity increases per unit installation area.

  The cylindrical electrode 40 is provided with gas inlets 45a and 45b and a plurality of gas blowing holes 46, and is grounded at one end thereof. The cylindrical electrode 40 is not necessarily grounded, and may be connected to a reference power source different from the DC power source 34. When the cylindrical electrode 40 is connected to a reference power supply different from the DC power supply 34, the reference voltage at the reference power supply is set to −1500 V or more and 1500 V or less.

  The gas inlet 45 a is for introducing a source gas dedicated to the dopant of the photoconductive layer 11 b to be supplied to the vacuum reaction chamber 4, and the gas inlet 45 b is a source gas to be supplied to the vacuum reaction chamber 4. The gas introduction ports 45 a and 45 b are connected to the raw material gas supply means 6. The gas introduction port 45 a is installed at a substantially central height position of the vacuum reaction chamber 4, and the gas introduction port 45 b is a height position corresponding to both end positions of the support 3 installed in the vacuum reaction chamber 4. Respectively.

  The plurality of gas blowing holes 46 are for blowing the source gas introduced into the cylindrical electrode 40 toward the cylindrical substrate 10 and are arranged at equal intervals in the vertical direction of the figure. In addition, they are arranged at equal intervals in the circumferential direction. The plurality of gas blowing holes 46 are formed in a circular shape having the same shape, and the hole diameter is, for example, not less than 0.5 mm and not more than 2 mm.

  The plate 41 is for selecting a state in which the vacuum reaction chamber 4 is opened or closed, and the support 3 can be taken in and out of the vacuum reaction chamber 4 by opening and closing the plate 41. Has been. The plate 41 is formed of the same conductive material as that of the cylindrical base body 10, but a deposition preventing plate 47 is attached to the lower surface side. This prevents a deposited film from being formed on the plate 41. The deposition preventing plate 47 is also formed of the same conductive material as that of the cylindrical substrate 10, but the deposition preventing plate 47 is detachable from the plate 41. Therefore, the deposition preventing plate 47 can be cleaned by removing it from the plate 41 and can be used repeatedly.

The plate 42 serves as a base for the vacuum reaction chamber 4 and is formed of a conductive material similar to that of the cylindrical substrate 10. The insulating member 44 interposed between the plate 42 and the cylindrical electrode 40 has a role of suppressing occurrence of arc discharge between the cylindrical electrode 40 and the plate 42. Such an insulating member 44 is made of, for example, a glass material (borosilicate glass, soda glass, heat-resistant glass, etc.), an inorganic insulating material (ceramics, quartz, sapphire, etc.) or a synthetic resin insulating material (fluorine resin such as tetrafluoroethylene, Polycarbonate, polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyamide, vinylon, epoxy, mylar, PEEK material, etc.), but it has insulating properties and sufficient heat resistance at the working temperature, vacuum There is no particular limitation as long as the material emits a small amount of gas. However, the insulating member 44 has a thickness greater than a certain thickness in order to prevent the insulating member 44 from being used due to warpage caused by the internal stress of the film formation body or the stress caused by the bimetal effect caused by the temperature rise during film formation. It is formed as having. For example, when the insulating member 44 is formed of a material having a thermal expansion coefficient of 3 × 10 ⁻⁵ / K or more and 10 × 10 ⁵ / K or less, such as ethylene tetrafluoride, the thickness of the insulating member 44 is 10 mm or more. Is set. When the thickness of the insulating member 44 is set in such a range, the stress generated at the interface between the insulating member 44 and an amorphous silicon (a-Si) film of 10 μm to 30 μm formed on the cylindrical substrate 10. The amount of warpage due to the difference in height in the axial direction between the end portion and the central portion in the horizontal direction is 200 mm in the horizontal direction (radial direction substantially orthogonal to the axial direction of the cylindrical base 10). It can be set to 1 mm or less, and the insulating member 44 can be used repeatedly.

  The plate 42 and the insulating member 44 are provided with gas discharge ports 42A and 44A and a pressure gauge 49. The exhaust ports 42A and 44A are for exhausting the gas inside the vacuum reaction chamber 4, and the pressure gauge 49 connected to the exhaust means 7 is for monitoring the pressure in the vacuum reaction chamber 4. Various known ones can be used.

  As shown in FIG. 2, the rotating means 5 is for rotating the support 3, and has a rotating motor 50 and a rotational force transmission mechanism 51. When film formation is performed by rotating the support 3 by the rotating means 5, the cylindrical base 10 rotates together with the support 3, so that the decomposition component of the source gas is uniformly distributed with respect to the outer periphery of the cylindrical base 10. Can be deposited.

  The rotation motor 50 applies a rotational force to the cylindrical base 10. The operation of the rotary motor 50 is controlled so as to rotate the cylindrical substrate 10 at 1 rpm or more and 10 rpm or less, for example. Various known motors can be used as the rotary motor 50.

  The rotational force transmission mechanism 51 is for transmitting and inputting the rotational force from the rotary motor 50 to the cylindrical base 10, and includes a rotation introduction terminal 52, an insulating shaft member 53, and an insulating flat plate 54.

The rotation introduction terminal 52 is for transmitting a rotational force while maintaining the vacuum in the vacuum reaction chamber 4. As such a rotation introduction terminal 52, a vacuum seal means such as an oil seal or a mechanical seal can be used with a rotary shaft having a double or triple structure.

  The insulating shaft member 53 and the insulating flat plate 54 are for inputting the rotational force from the rotary motor 50 to the support body 3 while maintaining the insulation state between the support body 3 and the plate 41. For example, the insulating member 44 It is made of a similar insulating material. Here, the outer diameter D2 of the insulating shaft member 53 is set to be smaller than the outer diameter (the inner diameter of the upper dummy base 38C described later) D3 during the film formation. More specifically, when the temperature of the cylindrical substrate 10 at the time of film formation is set to 200 ° C. or more and 400 ° C. or less, the outer diameter D2 of the insulating shaft member 53 is the outer diameter of the support 3 (described later). The inner diameter of the upper dummy substrate 38C) is set to be 0.1 mm or more and 5 mm or less, preferably about 3 mm. In order to satisfy this condition, the outer diameter D2 of the insulating shaft member 53 and the outer diameter of the support 3 (the upper dummy substrate 38C described later) are formed during non-film formation (in a room temperature environment (for example, 10 ° C. to 40 ° C.)). The difference from the inner diameter D3 is set to 0.6 mm or more and 5.5 mm or less.

  The insulating flat plate 54 is intended to prevent foreign matters such as dust and dust falling from above when the plate 41 is removed from adhering to the cylindrical base body 10, and has an outer diameter larger than the inner diameter D3 of the upper dummy base body 38C. It is formed in a disk shape having a diameter D4. The diameter D4 of the insulating flat plate 54 is 1.5 to 3 times the diameter D3 of the cylindrical substrate 10. For example, when the cylindrical substrate 10 having a diameter D3 of 30 mm is used, the diameter of the insulating flat plate 54 is used. D4 is about 50 mm.

  When such an insulating flat plate 54 is provided, it is possible to suppress abnormal discharge caused by foreign matter attached to the cylindrical substrate 10, and thus it is possible to suppress the occurrence of film formation defects. Thereby, the yield at the time of forming the electrophotographic photosensitive member 1 can be improved, and the occurrence of image defects when the image is formed using the electrophotographic photosensitive member 1 can be suppressed.

As shown in FIG. 2, the source gas supply means 6 includes a plurality of source gas tanks 60, 61, 62, 63, a dopant dedicated gas tank 64 for the photoconductive layer 11b, a plurality of pipes 60A, 61A, 62A, 63A, 64A, Valves 60B, 61B, 62B, 63B, 64B, 60C, 61C, 62C, 63C, 64C and a plurality of mass flow controllers 60D, 61D, 62D, 63D, 64D are provided, and piping 65a, 65b and gas inlet 45a , 45b to the cylindrical electrode 40. Each of the source gas tanks 60 to 64 is filled with, for example, B ₂ H ₆ , H ₂ (or He), CH _4, or SiH ₄ . Valves 60B to 64B, 60C to 64C and mass flow controllers 60D to 64D are for adjusting the flow rate, composition and gas pressure of each raw material gas component introduced into the vacuum reaction chamber 4 or the dopant exclusive gas component of the photoconductive layer 11b. It is. Of course, in the source gas supply means 6, the type of gas to be filled in each source gas tank 60 to 64, or the number of the plurality of source tanks 60 to 64 depends on the type or composition of the film to be formed on the cylindrical substrate 10. What is necessary is just to select suitably according to.

  The exhaust means 7 is for exhausting the gas in the vacuum reaction chamber 4 to the outside through the gas exhaust ports 42 </ b> A and 44 </ b> A, and includes a mechanical booster pump 71 and a rotary pump 72. These pumps 71 and 72 are controlled in operation according to the monitoring result of the pressure gauge 49. That is, the exhaust means 7 can maintain the vacuum reaction chamber 4 in a vacuum based on the monitoring result of the pressure gauge 49, and can set the gas pressure in the vacuum reaction chamber 4 to a target value. The pressure in the vacuum reaction chamber 4 is, for example, 1.0 Pa or more and 100 Pa or less.

(Method for forming deposited film)
Next, regarding a method for forming a deposited film using the plasma CVD apparatus 2, an electrophotographic photosensitive member 1 (see FIG. 1) in which an amorphous silicon (a-Si) film is formed as a photosensitive layer 11 on a cylindrical substrate 10 is used. A case of manufacturing will be described as an example.

  First, when forming a deposited film (a-Si film) on the cylindrical substrate 10, the plate 41 of the plasma CVD apparatus 2 was removed and a plurality of cylindrical substrates 10 (two in the drawing) were supported. The support 3 is set inside the vacuum reaction chamber 4 and the plate 41 is attached again.

  In supporting the two cylindrical bases 10 with respect to the support 3, the lower dummy base 38 </ b> A, the cylindrical base 10, the intermediate dummy base 38 </ b> B, the cylindrical base 10, and the main part of the support 3 are covered on the flange portion 30. The upper dummy bases 38C are sequentially stacked.

  As each of the dummy bases 38A to 38C, a conductive or insulating base whose surface has been subjected to a conductive treatment is selected according to the use of the product. Usually, a cylinder made of the same material as the cylindrical base 10 is used. What was formed in the shape is used.

  Here, the lower dummy base 38 </ b> A is for adjusting the height position of the cylindrical base 10. The intermediate dummy base body 38B is for suppressing the occurrence of film formation defects on the cylindrical base body 10 due to arc discharge generated between the end portions of the adjacent cylindrical base bodies 10. The intermediate dummy base body 38B has a minimum length (1 cm in this example) that can prevent arc discharge, and the surface side corner portion has a curvature of 0.5 mm or more by curved surface processing or end surface processing. The chamfered portion is used so that the length in the axial direction and the length in the depth direction of the part cut in the above are 0.5 mm or more. The upper dummy base 38C is for preventing the deposition film from being formed on the support 3 and suppressing the occurrence of film formation defects due to the peeling of the film formation body once deposited during film formation. . The upper dummy base 38 </ b> C is in a state in which a part protrudes above the support 3.

  Next, the vacuum reaction chamber 4 is sealed, the cylindrical substrate 10 is rotated by the rotating means 5 via the support 3, the cylindrical substrate 10 is heated, and the vacuum reaction chamber 4 is depressurized by the exhaust means 7.

  The cylindrical base 10 is heated, for example, by supplying electric power to the heater 37 from the outside to cause the heater 37 to generate heat. Due to the heat generated by the heater 37, the cylindrical substrate 10 is heated to a target temperature. The temperature of the cylindrical substrate 10 is selected depending on the type and composition of the film to be formed on its surface. For example, when forming an amorphous silicon (a-Si) film, the temperature is set in the range of 250 ° C. or more and 300 ° C. or less. The heater 37 is kept substantially constant by turning the heater 37 on and off.

On the other hand, the vacuum reaction chamber 4 is decompressed by exhausting the gas from the vacuum reaction chamber 4 through the gas discharge ports 42A and 44A by the exhaust means 7. The degree of depressurization of the vacuum reaction chamber 4 is determined by monitoring the pressure in the vacuum reaction chamber 4 with a pressure gauge 49 (see FIG. 2), and with a mechanical booster pump 71 (see FIG. 2) and a rotary pump 72 (see FIG. 2). ), For example, about 10 ⁻³ Pa.

  Next, when the temperature of the cylindrical substrate 10 reaches the desired temperature and the pressure in the vacuum reaction chamber 4 reaches the desired pressure, the source gas is supplied to the vacuum reaction chamber 4 by the source gas supply means 6 and the cylindrical electrode A pulsed DC voltage is applied between 40 and the support 3. As a result, glow discharge occurs between the cylindrical electrode 40 and the support 3 (cylindrical substrate 10), the source gas component is decomposed, and the decomposed component of the source gas is deposited on the surface of the cylindrical substrate 10.

On the other hand, in the exhaust means 7, the gas pressure in the vacuum reaction chamber 4 is maintained within the target range by controlling the operations of the mechanical booster pump 71 and the rotary pump 72 while monitoring the pressure gauge 49. That is, the inside of the vacuum reaction chamber 4 is maintained at a stable gas pressure by the mass flow controllers 60D to 63D in the source gas supply means 6 and the pumps 71 and 72 in the exhaust means 7. The gas pressure in the vacuum reaction chamber 4 is, for example, 1 Pa or more and 100 Pa or less.

  The supply of the raw material gas to the vacuum reaction chamber 4 is performed by controlling the mass flow controllers 60D-64D while appropriately controlling the open / closed state of the valves 60B-64B, 60C-64C, thereby obtaining the raw material gas in the raw material gas tanks 60-64. It introduce | transduces into the inside of the cylindrical electrode 40 through piping 60A-64A, 65a, 65b and gas inlet 45a, 45b with the composition and flow volume of these. The source gas introduced into the cylindrical electrode 40 is blown out toward the cylindrical substrate 10 through a plurality of gas blowing holes 46. Then, the charge injection blocking layer 11, the photoconductive layer 11b, and the surface layer 12 are formed on the surface of the cylindrical substrate 10 by appropriately switching the composition of the source gas by the valves 60B to 64B, 60C to 64C and the mass flow controllers 60D to 64D. Are sequentially stacked.

  The application of the pulsed DC voltage between the cylindrical electrode 40 and the support 3 is performed by controlling the DC power supply 34 by the control unit 35.

  In general, when high frequency power of 13.56 MHz RF band or higher is used, ion species generated in the space are accelerated by an electric field and attracted in a direction according to positive and negative polarities. Since the ionic species are continuously reversed, before the ionic species reach the cylindrical substrate 10 or the discharge electrode, recombination is repeated in the space to form a silicon compound such as gas or polysilicon powder again. Exhausted.

  On the other hand, a pulsating DC voltage is applied so that the cylindrical substrate 10 has a positive or negative polarity to accelerate the cations to collide with the cylindrical substrate 10, and the impact causes fine irregularities on the surface. When film formation of amorphous silicon (a-Si) is performed while sputtering, amorphous silicon (a-Si) having a surface with very few irregularities is obtained. The inventors named this phenomenon the “ion sputtering effect”.

  In order to obtain an ion sputtering effect efficiently in such a plasma CVD method, it is necessary to apply electric power that avoids continuous reversal of polarity. In addition to the pulse-shaped rectangular wave, a triangular wave, DC power or DC voltage is useful. The same effect can be obtained with AC power adjusted so that all voltages have either positive or negative polarity. The polarity of the applied voltage can be freely adjusted in consideration of the film forming speed determined by the density of the ion species and the polarity of the deposited species depending on the type of the source gas.

  Here, in order to obtain an ion sputtering effect efficiently by using a pulse voltage, the potential difference between the support 3 (cylindrical substrate 10) and the cylindrical electrode 40 is set within a range of, for example, 50 V or more and 3000 V or less. In consideration of the film rate, it is preferably in the range of 500 V or more and 3000 V or less.

  More specifically, when the cylindrical electrode 40 is grounded, the control unit 35 has a negative pulse shape within a range of −3000V to −50V with respect to the support (conductive column 31). A DC potential V1 is supplied, or a positive pulsed DC potential V1 within a range of 50V to 3000V is supplied.

On the other hand, when the cylindrical electrode 40 is connected to a reference electrode (not shown), the pulsed DC potential V1 supplied to the support (conductive column 31) is equal to the target potential difference ΔV and the reference. A difference value (ΔV−V2) from the potential V2 supplied from the power source is set. The potential V2 supplied from the reference power source is set to −1500 V or more and 1500 V or less when a negative pulse voltage is applied to the support 3 (cylindrical substrate 10), and the support 3 (cylindrical substrate 10). When a positive pulse voltage is applied to the voltage, the voltage is set to -1500V or more and 1500V or less.

  The control unit 35 also controls the DC power supply 34 so that the frequency (1 / T (sec)) of the DC voltage is 300 kHz or less and the duty ratio (T1 / T) is 20% or more and 90% or less.

  The duty ratio in the present invention means one cycle (T) of a pulsed DC voltage (from the moment when a potential difference is generated between the cylindrical substrate 10 and the cylindrical electrode 40 to the next moment when the potential difference is generated. Is defined as the time ratio occupied by potential difference occurrence T1. For example, a duty ratio of 20% means that the potential difference occurrence (ON) time in one cycle when applying a pulsed voltage is 20% of the entire cycle.

  Even if the amorphous silicon (a-Si) photoconductive layer 11b obtained by utilizing this ion sputtering effect has a thickness of 10 μm or more, the surface has small fine irregularities and the smoothness is hardly impaired. Therefore, the surface shape of the surface layer 12 when amorphous silicon carbide (a-SiC), which is the surface layer 12, is laminated on the photoconductive layer 11b by about 1 μm is a smooth surface reflecting the surface shape of the photoconductive layer 11b. It becomes possible to do. On the other hand, even when the surface layer 12 is laminated, the surface layer 12 can be formed as a smooth film with small fine irregularities by utilizing the ion sputtering effect.

  Here, in forming the charge injection blocking layer 11, the photoconductive layer 11b, and the surface layer 12, the mass flow controllers 60D to 63D and the valves 60B to 63B and 60C to 63C in the source gas supply means 6 are controlled to achieve the intended composition. The source gas is supplied to the vacuum reaction chamber 4 as described above.

For example, when the charge injection blocking layer 11 is formed as an amorphous silicon (a-Si) -based deposition film, a source gas such as a silicon (Si) -containing gas such as SiH ₄ (silane gas), B ₂ H ₆ or the like is used. A mixed gas of a dopant-containing gas and a diluent gas such as hydrogen (H ₂ ) or helium (He) is used. As the dopant-containing gas, in addition to the boron (B) -containing gas, a nitrogen (N) and oxygen (O) -containing gas can also be used.

In the case where the photoconductive layer 11b is formed as an amorphous silicon (a-Si) -based deposited film, as a source gas, a silicon (Si) -containing gas such as SiH ₄ (silane gas) and hydrogen (H ₂ ) or helium (He) are used. Etc.) is used. In the photoconductive layer 11b, hydrogen gas is used as a diluting gas so that hydrogen (H) or halogen element (F, Cl) is contained in the film in an amount of 1 atomic% to 40 atomic% for dangling bond termination, Alternatively, a halogen compound may be included in the source gas. In addition, in the source gas, in order to obtain desired characteristics with respect to electrical characteristics such as dark conductivity and photoconductivity and optical band gap, Group 12 and Group 13 elements (hereinafter referred to as “Group”) as dopants. The above-mentioned characteristics include a group 12 element, abbreviated as “group 13 element”) or a group 15 or a group 16 element in the periodic table (hereinafter abbreviated as “group 15 element” or “group 16 element”). In order to adjust the above, elements such as carbon (C) and oxygen (O) may be contained.

For example, as the Group 13 element and the Group 15 element, boron (B) and phosphorus (P) are excellent in covalent bondability and can change the semiconductor characteristics sensitively, and excellent photosensitivity can be obtained. Is desirable. When the group 13 element or the group 15 element is contained together with elements such as carbon (C) and oxygen (O) in the charge injection blocking layer 11, the content of the group 13 element is 0.1 ppm or more and 20000 ppm. Hereinafter, the content of the Group 15 element is 0.1 pp.
m is adjusted to 10000 ppm or less. In addition, when a group 13 element or a group 15 element is included together with elements such as carbon (C) and oxygen (O) in the photoconductive layer 11b, or alternatively, the charge injection blocking layer 11 and the photoconductive layer 11b. When elements such as carbon (C) and oxygen (O) are not included, the group 13 element is adjusted to 0.01 ppm to 200 ppm, and the group 15 element is adjusted to 0.01 ppm to 100 ppm. Is done. In addition, by changing the content of the Group 13 element or the Group 15 element in the source gas over time, the concentration of these elements may be provided with a gradient over the layer thickness direction. In this case, the content of the Group 13 element or the Group 15 element in the photoconductive layer 11b may be such that the average content in the entire photoconductive layer 11b is within the above range.

  For the photoconductive layer 11b, the amorphous silicon (a-Si) -based material may contain microcrystalline silicon (μc-Si). When this microcrystalline silicon (μc-Si) is included, Since dark conductivity and photoconductivity can be increased, there is an advantage that the degree of freedom in designing the photoconductive layer 22 is increased. Such microcrystalline silicon (μc-Si) can be formed by employing the film formation method described above and changing the film formation conditions. For example, in the glow discharge decomposition method, it can be formed by setting the temperature and DC pulse power of the cylindrical substrate 10 high and increasing the flow rate of hydrogen as a dilution gas. Further, in the photoconductive layer 11b containing microcrystalline silicon (μc-Si), the same elements as described above (Group 13 element, Group 15 element, carbon (C), oxygen (O), etc.) May be added.

When the surface layer 12 is formed as an amorphous silicon carbide (a-SiC) -based deposited film, a mixture of a silicon (Si) -containing gas such as SiH ₄ (silane gas) and a C-containing gas such as CH ₄ is used as a source gas. Supply gas. The composition ratio of silicon (Si) and carbon (C) in the source gas may be changed continuously or intermittently. That is, as the C ratio increases, the deposition rate tends to be slower. Therefore, the C ratio is low for the portion close to the photoconductive layer 11b in the surface layer 12, while the C ratio is high for the free surface side. You may make it form the surface layer 12 so that it may become. For example, on the photoconductive layer 11b side (interface side) of the surface layer 12, the x value (carbon ratio) in hydrogenated amorphous silicon carbide (a-Si1 _{- xCx} : H) exceeds 0 and is 0.8. After depositing the first silicon carbide (SiC) layer having a relatively high silicon (Si) composition ratio of less than 2, the C concentration was increased to an x value (carbon ratio) of 0.95 or more and less than 1.0. It may be a two-layer structure in which a silicon carbide (SiC) layer is deposited.

  The film thickness of the first silicon carbide (SiC) layer is determined from the withstand voltage, the residual potential, the film strength, etc., and is usually 0.1 μm to 2 μm, preferably 0.2 μm to 1 μm, optimally It is set to 0.3 μm or more and 0.8 μm or less. The film thickness of the second silicon carbide (SiC) layer is determined from withstand voltage, residual potential, film strength, life (wear resistance), etc., and is usually 0.01 μm or more and 2 μm or less, preferably 0.02 μm. The thickness is not less than 1 μm and optimally not less than 0.05 μm and not more than 0.8 μm.

The surface layer 12 can also be formed as an aC layer as described above. In this case, a C-containing gas such as C ₂ H ₂ (acetylene gas) or CH ₄ (methane gas) is used as the source gas. The thickness of the surface layer 12 is usually 0.1 μm to 2 μm, preferably 0.2 μm to 1 μm, and optimally 0.3 μm to 0.8 μm.

In the case where the surface layer 12 is formed as an aC layer, since the binding energy of the C—O bond is smaller than that of the Si—O bond, the surface layer 12 is formed of an amorphous silicon (a-Si) material. Compared with the case where it does, it can suppress more reliably that the surface of the surface layer 12 oxidizes. Therefore, when the surface layer 12 is formed as an amorphous carbon (a-C) layer, it is appropriately suppressed that the surface of the surface layer 12 is oxidized by ozone generated by corona discharge during printing. It is possible to suppress the occurrence of image flow in a high temperature and high humidity environment.

When film formation on the cylindrical substrate 10 is completed, the electrophotographic photosensitive member 1 shown in FIG. 1 can be obtained by extracting the cylindrical substrate 10 from the support 3. After the film formation, in order to remove the film formation residue, each member in the vacuum reaction chamber 4 is disassembled and washed with acid, alkali, blast, or the like, and there is no dust generation that causes a defect in the next film formation. In this way, wet etching is performed. It is also effective to perform gas etching using halogen-based (ClF ₃ , CF ₄ , NF ₃ , SiF ₆ or a mixed gas thereof) instead of wet etching.

After forming the deposited film in this way, the detection region 12a is formed in the surface layer 12. The detection region 12a is formed by removing with a laser such as a CO ₂ laser, YAG laser, UV laser, or excimer laser, or wet etching with a potassium hydroxide (KOH) solution or a sodium hydroxide (NaOH) solution. You can do it.

  The detection region 12a can also be formed by the following method. After the surface layer 12 is formed to a predetermined thickness, the cylindrical substrate 10 is extracted from the support 3 and masked with a polyimide tape or the like at a predetermined position, and the support 3 supporting the cylindrical substrate 10 is again subjected to a vacuum reaction. In the chamber 4, the surface layer 12 is further deposited. Thereafter, the cylindrical substrate 10 is extracted from the support 3 and the masked polyimide is removed to form the detection region 12a. In this way, the surface layer 12 is deposited in two steps, the thickness deposited in the first time and the thickness deposited in the second time are controlled, and the detection region for the thickness of the surface layer 12 in the region adjacent to the detection region 12a 12, the ratio of the thickness of the surface layer 12 is adjusted to 20 to 80%.

(Image forming device)
The image forming apparatus shown in FIG. 3 employs the Carlson method as an image forming method, and includes an electrophotographic photosensitive member 1, a charger 111, an exposure device 112, a developing device 113, a transfer device 114, a fixing device 115, and a cleaning device. 116 and a static eliminator 117.

  The charger 111 plays a role of charging the surface of the electrophotographic photoreceptor 1 to a negative polarity. The charging voltage is set to, for example, 200 V or more and 1000 V or less. In this embodiment, the charger 111 employs a contact charger configured by covering a core metal with conductive rubber or PVDF (polyvinylidene fluoride), for example, but instead includes a discharge wire. A non-contact type charger (for example, a corona charger) may be adopted.

  The exposure device 112 plays a role of forming an electrostatic latent image on the electrophotographic photosensitive member 1. Specifically, the exposure device 112 irradiates the electrophotographic photosensitive member 1 with exposure light (for example, laser light) having a specific wavelength (for example, 650 nm or more and 780 nm or less) in accordance with an image signal, so that the electrophotographic image is in a charged state. An electrostatic latent image is formed by attenuating the potential of the exposure light irradiation portion of the photoreceptor 1. As the exposure device 112, for example, an LED head in which a plurality of LED elements (wavelength: 680 nm) are arranged can be employed.

  Of course, as the light source of the exposure device 112, a light source capable of emitting laser light can be used instead of the LED element. That is, an optical system including a polygon mirror may be used in place of the exposure device 112 such as an LED head. Alternatively, by adopting an optical system including a lens and a mirror through which reflected light from a document is passed, an image forming apparatus having a configuration of a copying machine can be obtained.

  The developing device 113 plays a role of developing the electrostatic latent image of the electrophotographic photosensitive member 1 to form a toner image. The developing device 113 in this example includes a magnetic roller 113A that magnetically holds a developer (toner) T.

  The developer T constitutes a toner image formed on the surface of the electrophotographic photosensitive member 1 and is triboelectrically charged in the developing device 113. Examples of the developer T include a two-component developer containing a magnetic carrier and an insulating toner, and a one-component developer containing a magnetic toner.

  The magnetic roller 113 </ b> A plays a role of transporting the developer to the surface (development region) of the electrophotographic photosensitive member 1. The magnetic roller 113A conveys the developer T frictionally charged in the developing unit 113 in the form of a magnetic brush adjusted to a certain head length. The transported developer T adheres to the surface of the electrophotographic photosensitive member 1 by electrostatic attraction with the electrostatic latent image in the developing area of the electrophotographic photosensitive member 1 to form a toner image (electrostatic latent image). Visualize). The charge polarity of the toner image is opposite to the charge polarity of the surface of the electrophotographic photoreceptor 1 when image formation is performed by regular development, and the electrophotographic photoreceptor 1 when image formation is performed by reversal development. The charge polarity of the surface is the same.

  The developing device 113 adopts a dry development method in this example, but may adopt a wet development method using a liquid developer.

  The transfer device 114 plays a role of transferring the toner image of the electrophotographic photosensitive member 1 to the recording medium P supplied to the transfer region between the electrophotographic photosensitive member 1 and the transfer device 114. The transfer device 114 in this example includes a transfer charger 114A and a separation charger 114B. In the transfer device 114, the back surface (non-recording surface) of the recording medium P is charged with a reverse polarity to the toner image in the transfer charger 114 </ b> A. The image is transferred. In the transfer unit 114, simultaneously with the transfer of the toner image, the back surface of the recording medium P is AC-charged in the separation charger 114B, and the recording medium P is quickly separated from the surface of the electrophotographic photosensitive member 1.

  As the transfer device 114, it is possible to use a transfer roller that is driven by the rotation of the electrophotographic photosensitive member 1 and disposed with a small gap (usually 0.5 mm or less) from the electrophotographic photosensitive member 1. is there. The transfer roller is configured to apply a transfer voltage that attracts the toner image on the electrophotographic photosensitive member 1 onto the recording medium P by, for example, a DC power source. When a transfer roller is used, a transfer separation device such as the separation charger 114B can be omitted.

  The fixing device 115 plays a role of fixing the toner image transferred to the recording medium P to the recording medium P, and includes a pair of fixing rollers 115A and 115B. The fixing rollers 115A and 115B are, for example, coated on a metal roller with tetrafluoroethylene or the like. The fixing device 115 can fix the toner image on the recording medium P by applying heat and pressure to the recording medium P that passes between the pair of fixing rollers 115A and 115B.

  The cleaning device 116 plays a role of removing toner remaining on the surface of the electrophotographic photosensitive member 1 and includes a cleaning blade 116A. The cleaning blade 116 </ b> A plays a role of scraping residual toner from the surface of the electrophotographic photosensitive member 1. The cleaning blade 116A is made of, for example, a rubber material mainly composed of polyurethane resin.

The static eliminator 117 plays a role of removing surface charges of the electrophotographic photosensitive member 1 and can emit light having a specific wavelength (for example, 780 nm or more). The static eliminator 117 removes the surface charge (residual electrostatic latent image) of the electrophotographic photosensitive member 1 by irradiating the entire axial direction of the surface of the electrophotographic photosensitive member 1 with a light source such as an LED. It is configured.

  In the image forming apparatus 100 of this example, the above-described effects of the electrophotographic photoreceptor 1 can be obtained.

  Although the present example has been described above, it is needless to say that the present invention is not limited to only those shown in the embodiments and can be improved or changed without departing from the gist of the present invention.

  For example, as in the first modification shown in FIGS. 4A and 4B, the detection region 12 a is preferably arranged continuously along the circumferential direction of the surface layer 12. By arranging in this way, even if the thickness of the surface layer 12 varies in the circumferential direction, the thickness of the surface layer 12 in the detection region 12a corresponding to the thinnest portion of the surface layer 12 is uneven in the image. Since the thickness of the charging capability that causes image defects such as image defects is reached, the electrophotographic photosensitive member 1 can be replaced before image defects such as image irregularities occur, resulting in the occurrence of image defects such as image irregularities. Can be prevented.

  In the example shown in FIG. 4 (a), a plurality of detection regions 12a are continuously arranged along the circumferential direction of the surface layer 12, and in the example shown in FIG. 4 (b), one detection region 12a has one detection region 12a. It arrange | positions along the circumferential direction of the surface layer 12, and the same effect can be acquired also in any modification.

  Further, as in the second modified example shown in FIG. 5, a plurality of types of detection regions 12a may be provided (in the case of the first modified example, three types of detection regions 12a1, 12a2, and 12a3). FIG. 5 is a development view in which the surface layer 12 is cut open along the axial direction of the cylindrical substrate 10. And the thickness of the surface layer 12 in each detection area | region 12a1, 12a2, 12a3 is varied. That is, the detection region 12a is composed of a plurality of types, and the surface in each type of detection region 12a1, 12a2, 12a3 with respect to the thickness of the surface layer 12 in the region adjacent to each type of detection region 12a1, 12a2, 12a3. The thickness ratios of the layers 12 are different. By adopting such a configuration, the degree of decrease in the thickness of the surface layer 12 due to wear can be detected in stages, and the situation where the electrophotographic photosensitive member 1 must be replaced unexpectedly can be avoided. Specifically, the thickness of the surface layer 12 in the detection region 12a1 is set to 80% of the thickness of the surface layer 12 in the region adjacent to the detection region 12a1, and the thickness of the surface layer 12 in the detection region 12a2 is similarly set to 60. %, And the thickness of the surface layer 12 in the detection region 12a3 is 40%.

  In the second modification, three types of detection regions 12a1, 12a2, and 12a3 are used. However, the number of types is not limited to three, and any number may be used.

  Further, as in the third modification shown in FIG. 6, the surface layer 12 has a charging region that is charged by a charging unit that applies a charge, and the detection region 12 a is a charging region in the longitudinal direction of the cylindrical substrate 10. It may be arranged in a charged region within 20 mm from both ends of the. With this configuration, it is assumed that the thickness of the surface layer 12 in the detection region 12a becomes a charging capacity that causes image defects such as image unevenness, and an image notifying that effect is drawn on the recording medium. Also, the influence on the image quality can be suppressed. This is because the characteristic image is often arranged near the center of the recording medium.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 10 Cylindrical base | substrate 11 Photosensitive layer 11a Charge injection | pouring prevention layer 11b Photoconductive layer 12 Surface layer 12a Detection area 100 Image forming apparatus 111 Charger 112 Exposure device 113 Developing device 114 Transfer device 115 Fixing device 116 Cleaning device 117 Static eliminator

Claims (7)

An electrophotographic photosensitive member comprising a cylindrical substrate, a photosensitive layer including at least a photoconductive layer formed on the cylindrical substrate, and a surface layer formed on the photosensitive layer,
The surface layer has a detection region for detecting the degree of wear of the surface layer due to the use of the electrophotographic photosensitive member, and in the detection region relative to the thickness of the surface layer in a region adjacent to the detection region. An electrophotographic photoreceptor, wherein the thickness ratio of the surface layer is 20 to 80%.   2. The electrophotographic photosensitive member according to claim 1, wherein the size of the detection region is 20 [mu] m or more as viewed from the surface side of the surface layer.   The electrophotographic photosensitive member according to claim 1, wherein the size of the detection region is less than φ100 μm.   4. The electrophotographic photosensitive member according to claim 1, wherein the detection region is continuously arranged along a circumferential direction of the surface layer. 5.   The detection region has a plurality of types of detection regions, and the ratio of the thickness of the surface layer in each type of detection region to the thickness of the surface layer in a region adjacent to each type of detection region is different. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the electrophotographic photosensitive member is provided. The surface layer has a charging region that is charged by a charging means for applying a charge,
The said detection area | region is arrange | positioned in the said charging area within 20 mm from the both ends of the said charging area in the length direction of the said cylindrical base | substrate, The Claim 1 characterized by the above-mentioned. Electrophotographic photoreceptor.   An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1.

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