Image forming apparatus

Abstract

To solve the problem in which: dust is attached to a surface of a photoconductor drum in a configuration to perform cleaning of a lens array.SOLUTION: An image forming apparatus has: a photoconductor drum; a plurality of light-emitting devices for emitting exposure light; a lens array in which a plurality of lenses is arranged for condensing the exposure light emitted from the light-emitting devices to the surface of the photoconductor drum; and a cleaning member that is inserted into the surface of the photoconductor drum and the light emission surface of the lens array, for rubbing the surface of the photoconductor drum and the light irradiation surface of the lens array to clean the light emitting surface of the lens array. The cleaning member has a rubbing part that has a rubbing surface to be rubbed with the surface of the photoconductor drum. The rubbing surface to be rubbed with the surface of the photoconductor drum is formed of at least one kind of a material selected from the group consisting of nylon and a material negatively electrostatically charged more easily than nylon.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus using a photosensitive drum. [Background technology]

[0002] In electrophotographic image forming devices such as laser beam printers and digital copiers, a solid-state exposure head is one of the means for exposing a photosensitive drum. A solid-state exposure head arranges a plurality of light-emitting points such as LEDs (in this disclosure, this refers to inorganic LEDs; the same applies below) or organic ELs, which are light-emitting elements, in a substantially linear manner in a direction parallel to the rotation axis of the photosensitive drum (main scanning direction), and exposes the photosensitive drum all at once in the main scanning direction. This method is smaller in volume and does not have a driving unit compared to laser scanning exposure devices that use a polygon mirror for scanning, and is therefore advantageous for miniaturizing and reducing noise in image forming devices.

[0003] The solid-state exposure head is provided with a lens array in which a plurality of gradient index lenses are arranged in the main scanning direction facing the light-emitting element in order to form an image of the light beam emitted from the light-emitting element on the photosensitive drum. Since the focal length of this lens array is extremely short, the solid-state exposure head needs to be placed very close to the photosensitive drum, but toner may be floating near the photosensitive drum on the air flow for cooling the inside of the image forming device. If such floating toner adheres to the emission surface of the lens array, the amount of light irradiating the photosensitive drum becomes non-uniform, resulting in defective images such as uneven density. For this reason, the solid-state exposure head requires a cleaning means for cleaning the surface of the lens array.

[0004] As an example of a cleaning means, Patent Document 1 discloses a means for cleaning a lens array by providing a guide unit that controls the distance between the photosensitive drum and the cleaning member. However, in an image forming device in which the mounting density of the internal unit is increased in an effort to reduce size, it may be difficult to provide such a guide unit near the solid-state exposure head.

[0005] As a method for responding to such a demand for miniaturization of the internal unit, Patent Document 2 discloses a means for cleaning the surface of the lens array by providing a drum rubbing portion for an electrophotographic photosensitive drum on the surface of the cleaning member facing the photosensitive drum, and bringing the drum rubbing portion into contact with the photosensitive drum. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4848709 [Patent Document 2] Patent No. 4743303 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the case of a configuration in which the lens array is cleaned while being brought into contact with the drum sliding portion as described in Patent Document 2, when an animal fiber such as wool is selected as the contact member that is brought into contact with the photosensitive drum, there is a problem in that the electrostatic action between the drum sliding portion and the photosensitive drum during the cleaning operation attracts toner, dust and dirt remaining inside the machine to the surface of the photosensitive drum, impeding image formation. [Means for solving the problem]

[0008] The above object can be achieved by the present invention, namely: A photosensitive drum rotatable around a rotation axis; a plurality of light emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting element and a light exit surface facing the photosensitive drum, the lens array being configured so that a plurality of lenses are arranged in the direction of the rotation axis for focusing the exposure light emitted from the light emitting element onto the surface of the photosensitive drum; a cleaning member that is inserted between a surface of the photosensitive drum and the light emission surface of the lens array, and cleans the light emission surface of the lens array while rubbing the surface of the photosensitive drum and the light irradiation surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having the cleaning member has a rubbing portion having a rubbing surface that is caused to rub against the surface of the photosensitive drum, 13. An image forming apparatus, comprising: a surface that rubs against the surface of the photosensitive drum, the surface being made of at least one material selected from the group consisting of nylon and materials that are more likely to be charged with negative static electricity than nylon. Effect of the Invention

[0009] According to the present invention, in a configuration in which a guide member for contacting a cleaning member with the surface of a lens array is sandwiched between the lens array and a photosensitive drum, and the lens array is cleaned while the photosensitive drum is in contact with the drum sliding portion for the photosensitive drum, adhesion of dust and dirt to the surface of the photosensitive drum during cleaning operation can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of an electrophotographic apparatus used in the present disclosure. [Diagram 2] FIG. 1 is a diagram showing an example of a solid-state exposure apparatus used in the present disclosure. [Diagram 3] FIG. 2 is a diagram showing an example of a cleaning member used in the present disclosure. [Figure 4] FIG. 2 is a diagram showing an example of a cleaning form of a solid-state exposure apparatus used in the present disclosure. [Diagram 5] 10A and 10B are diagrams illustrating an example of a charging method for confirming the charging polarity of a drum sliding portion used in the present disclosure. [Figure 6] 11A and 11B are diagrams illustrating an example of a method for checking the charge polarity of the drum sliding portion used in the present disclosure. [Figure 7] FIG. 2 is a diagram showing an example of a photosensitive drum used in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below with reference to preferred embodiments. [Image forming device] The image forming apparatus shown in Fig. 1 includes four image forming units 102Y, 102M, 102C, and 102K that form toner images of yellow, magenta, cyan, and black, respectively. The image forming units 102Y, 102M, 102C, and 102K include photosensitive drums 103Y, 103M, 103C, and 103K that are rotatable about their respective rotation axes. Around the photosensitive drums, there are provided chargers 104Y, 104M, 104C, and 104K, solid-state (LED) exposure heads 501Y, 501M, 501C, and 501K, and developers 106Y, 106M, 106C, and 106K.

[0012] <Image formation process> The photosensitive drums 103Y, 103M, 103C, and 103K, which are uniformly charged by the chargers 104Y, 104M, 104C, and 104K, are exposed by the LED exposure heads 501Y, 501M, 501C, and 501K to form electrostatic latent images. The electrostatic latent images are visualized as toner images of the respective colors by the developers 106Y, 106M, 106C, and 106K, and transferred to the intermediate transfer belt 107 at the primary transfer portions Ty, Tm, Tc, and Tk. The toner images of each color superimposed on the intermediate transfer belt 107 are transferred collectively at a secondary transfer section T2 by a secondary transfer roller 109 onto a recording paper P transported from a paper feed section 101. The recording paper P onto which the toner images have been transferred is transported to a fixing device 110, where the toner images are fixed by heat and pressure, and then the recording paper P is discharged from a paper discharge section 111.

[0013] <Solid-state exposure equipment> FIG. 2 shows a cross-sectional view of a solid-state exposure head 201 as an example. A light-emitting substrate 202 on which a plurality of LED chips are arranged in the main scanning direction (the direction of the rotation axis of the photosensitive drum) and a lens array 206 on which a plurality of cylindrical gradient index lenses are arranged in the main scanning direction are held in a housing 205. The light-emitting substrate 202 has a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum. The material of the housing 205 is a plate material obtained by plating a zinc-plated steel plate or a cold-rolled steel plate afterwards. The lens array 206 has a light entrance surface facing the light-emitting elements and a light exit surface facing the photosensitive drum, and is configured by arranging a plurality of lenses in the direction of the rotation axis for concentrating the exposure light emitted from the light-emitting elements on the surface of the photosensitive drum. The lens array 206 forms an image of the light beams emitted from the LED light-emitting points 203 on the photosensitive drum 103 as an equal-magnification erect image. At this time, the distance from the LED light emitting point to the entrance surface of the lens array 206 and the distance from the exit surface of the lens array 206 to the surface of the photosensitive drum 103 are substantially equal. The distance between the LED light emitting point 203 and the incidence surface of the lens array 206 must be highly accurate on the order of μm, and after this distance is precisely adjusted, the light emitting substrate 202 and the lens array 206 are fixed to the housing 205 by adhesive. In this embodiment, an LED is used as the solid-state exposure light source, and the light emitting substrate 202, lens array 206, and housing 505 integrated into one unit is called the solid-state exposure head 201.

[0014] <Cleaning mechanism> As mentioned above, if toner or other foreign matter adheres to the exit surface of the lens array 206, it partially blocks the light emitted from the light-emitting elements, causing a deterioration in the quality of the output image. Therefore, the exit surface of the lens array 206 needs to be cleaned periodically. The cleaning means 300 is inserted between the surface of the photosensitive drum 103 and the light emission surface of the lens array 206. The cleaning means 300 cleans the light emission surface of the lens array 206 while rubbing the surface of the photosensitive drum 103 and the light irradiation surface of the lens array 206 from one end side to the other end side in the longitudinal direction of the lens array 206. 3 shows an example of an overall view of the cleaning means 300 of the solid-state exposure head 501 used in the present invention. The cleaning means 300 is generally in the form of a long and thin rod, and is provided with a gripping part 302 at one end of a rod-shaped body part 303 and a cleaning part 301 at the other end. The body portion 303 is formed of an engineering plastic such as ABS or PP.

[0015] <Cleaning material and drum sliding part> FIG. 4 shows a state in which the cleaning member 401 of the cleaning means 300 is in contact with the lens array 206 for cleaning. The cleaning unit 301 includes a cleaning member 401 on a surface facing the lens array 206, and a drum rubbing unit 402 having a rubbing surface facing the photosensitive drum 103 (hereinafter also referred to as the "rubbing surface that rubs against the surface of the photosensitive drum" or the "rubbing surface of the drum rubbing unit"). The cleaning member 401 is a blade made of, for example, urethane rubber, and uses the tip of the blade to wipe the lens array emission surface and remove foreign matter. Other materials such as silicone rubber and chloroprene rubber may also be used. It is also possible to use a nonwoven fabric or felt instead of a blade for cleaning. The drum rubbing portion 402 needs to have a rubbing surface that rubs against the surface of the photosensitive drum made of at least one material selected from the group consisting of nylon and materials that are more likely to be negatively charged than nylon. It is also preferable that the rubbing surface that rubs against the surface of the photosensitive drum is made of at least one material selected from the group consisting of rayon and materials that are more likely to be negatively charged than rayon. Specifically, preferred members include members made of nylon (polyamide), rayon, polyester, and polyurethane. The rubbing surface that is rubbed against the surface of the photosensitive drum preferably contains at least one selected from the group consisting of rayon, polyester, and polyurethane, and more preferably contains polyester or polyurethane. Since polyester and polyurethane have a similar electrostatic charge series to the binder resin on the outermost surface of the photosensitive drum, it is possible to suppress the amount of frictional charge between the sliding surface of the drum sliding part and the photosensitive drum surface during cleaning operation, and the amount of charge on the photosensitive drum surface after cleaning operation can be suppressed. As a result, it is believed that this is because it is possible to suppress the electrostatic adhesion of dust, dirt, and toner inside the machine to the photosensitive drum surface. The sliding surface of the drum sliding part may be made of one kind of material or two or more kinds of materials as a mixture or copolymer, and may be in the form of a woven fabric or a nonwoven fabric.

[0016] The charge polarity of the sliding surface of the drum sliding portion can be confirmed by the following means, as shown in FIG. A 25 μm thick biaxially oriented polyamide film (ONy film: manufactured by Unitika Ltd., product name Emblem ON-25) 501 is fixed so as to be in close contact with an aluminum plate 502 connected to earth. The drum rubbing part 402 fixed to an aluminum rod 503 is moved back and forth 10 times in the direction of the arrow on this plate to be frictionally charged. In addition, to prevent the charged electric charge from escaping from the rubbing surface of the drum rubbing part, the handle of the aluminum rod must be insulated 504 with insulating tape made of fluororesin or polyimide. The drum sliding portion thus triboelectrically charged is immediately placed in a Faraday cage shown in Fig. 6, and the polarity of the triboelectric charge is confirmed by an electrometer. The Faraday cage is made of metal double cups 601 and 602, and the insulation resistance between the double cups is 1 x 10 12 An insulating plate 603 made of fluororesin, acrylic resin or polycarbonate resin having a resistance of Ω or more is provided. The drum sliding part 402 charged as described above is housed in a double cup inner cylinder 601, and an electrometer 604 is connected to the double cup inner cylinder 601, and the line between the inner cylinder and the electrometer is earthed via a capacitor 605. The charge amount measurement is based on JIS L1094 (Test method for electrostatic charge of woven and knitted fabrics). In the present invention, a digital electrometer R8252 (product name) manufactured by Advantest Corporation is used as the electrometer 604.

[0017] [Photosensitive drum] As an example of the photosensitive drum 103 used in the present invention, a support and a laminated type photosensitive layer formed on the support are shown in Fig. 7. In Fig. 7, 701 is a support, 702 is an undercoat layer, 703 is a charge generation layer, and 704 is a charge transport layer. <Support> The support is preferably one having electrical conductivity (conductive support), and examples thereof include supports made of metals (alloys) such as aluminum, iron, copper, gold, stainless steel, and nickel, metals having a conductive coating on the surface, and insulating supports. Examples of insulating supports include supports made of plastics such as polyester resin, polycarbonate resin, and polyimide resin, glass, and paper. Examples of conductive coatings include thin metal films such as aluminum, chromium, silver, and gold, thin conductive material films such as indium oxide, tin oxide, and zinc oxide, and thin conductive ink films containing silver nanowires. The shape of the support is preferably cylindrical. The surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like. The shape of the support may be, for example, a cylindrical shape, a film shape, etc. Among these, a cylindrical aluminum support is superior in terms of mechanical strength, electrophotographic properties, and cost. A raw tube may be used as the support as it is, but the surface of the raw tube may be subjected to physical treatment such as cutting, honing, or blasting, or to chemical treatment using an acid or the like, in order to improve electrical properties and suppress interference fringes, and then the support may be used.

[0018] <Conductive layer> The conductive layer is an optional layer. The conductive layer is a layer that may be disposed on the conductive support and between the conductive support and the photosensitive layer, more specifically, in the layer order of conductive support / conductive layer / undercoat layer / photosensitive layer. By providing the conductive layer, scratches and irregularities on the surface of the conductive support can be concealed and light reflection on the support surface can be controlled. The conductive layer contains conductive particles and a resin. The conductive particles may be made of a material such as metal oxide, metal, or carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, and bismuth oxide. Among these, metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Of the above materials for the conductive particles, metal oxides are preferred, and in particular, titanium oxide, tin oxide, and zinc oxide are more preferred. Regarding the metal oxide, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum itself or an oxide thereof. The conductive particles may have a laminated structure having a core material and a coating layer that coats the core material. Examples of the core material include titanium oxide, barium sulfate, zinc oxide, etc. Examples of the coating layer include metal oxides such as tin oxide. The coating layer and the surface treated with the silane coupling agent are much thicker than each other. When a metal oxide is used as the conductive particles, the volume average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0019] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. Furthermore, the conductive layer may contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like. The conductive layer can be obtained by providing a coating film of a coating liquid for conductive layer containing the above-mentioned materials and solvent on a support and drying the coating film. Examples of the solvent used in the coating liquid include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of a method for dispersing the conductive particles in the coating liquid for the conductive layer include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser. The average thickness of the conductive layer is preferably from 0.1 μm to 50 μm, and particularly preferably from 3 μm to 40 μm.

[0020] <Undercoat layer> An undercoat layer having a barrier function or an adhesive function may be provided on the support or the conductive layer, if necessary. The undercoat layer is obtained by dissolving a resin in a solvent to prepare a coating liquid for the undercoat layer, forming a coating film of the coating liquid for the undercoat layer, and drying it. The undercoat layer contains a resin and a substance that improves electrical properties. Each will be explained. The undercoat layer contains a resin. The resin may be a cured film obtained by polymerizing a composition containing a monomer having a polymerizable functional group in a coating liquid to form a coating film from the coating liquid (curing by polymerization of the monomer), to obtain the undercoat layer. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin. Examples of the polymerizable functional group contained in the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0021] For the purpose of improving electrical properties, the undercoat layer contains an electron transporting material, a metal oxide, a metal, etc. Among these, it is preferable to use an electron transporting material or a metal oxide. Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the monomer having the polymerizable functional group described above. Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, strontium titanate, silicon dioxide, etc. Examples of metals include gold, silver, aluminum, etc.

[0022] The metal oxide contained in the undercoat layer may be surface-treated with a surface treatment agent such as a silane coupling agent. The surface treatment of the metal oxide can be carried out by a common method, such as a dry method or a wet method. In the dry method, while stirring the metal oxide in a mixer capable of high speed stirring such as a Henschel mixer, an alcohol aqueous solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent is added to the metal oxide to uniformly disperse the metal oxide, followed by drying. In the wet method, the metal oxide and the surface treatment agent are stirred in a solvent or dispersed in a sand mill using glass beads or the like, and the solvent is removed by filtration or distillation under reduced pressure. After the solvent is removed, it is preferable to further bake the mixture at 100° C. or higher.

[0023] The undercoat layer may further contain additives, for example, known materials such as metal powder such as aluminum, conductive substances such as carbon black, metal chelate compounds, and organometallic compounds. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film of this on a support or a conductive layer, and drying and / or curing it. Examples of the solvent used in the coating solution for the undercoat layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, halogenated aliphatic hydrocarbons, aromatic compounds, etc. In the present invention, it is preferable to use alcohol-based and ketone-based solvents. Examples of a dispersion method for preparing a coating solution for the undercoat layer include methods using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, and a liquid collision type high-speed disperser. When an undercoat layer is used, the average thickness thereof is preferably from 0.05 μm to 50 μm, and more preferably from 0.3 μm to 25 μm.

[0024] <Charge generation layer> Directly over the undercoat layer is a charge generating layer. Examples of the charge generating material include perylene pigments, anthraquinone derivatives, anthranthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, indigo derivatives, thioindigo derivatives, phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines, and bisbenzimidazole derivatives. Among these, phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine are preferred. As the oxytitanium phthalocyanine, preferred are oxytitanium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 9.0°, 14.2°, 23.9°, and 27.1° in CuKα characteristic X-ray diffraction, and oxytitanium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 9.5°, 9.7°, 11.7°, 15.0°, 23.5°, 24.1°, and 27.3°. As the chlorogallium phthalocyanine, preferred are chlorogallium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 7.4°, 16.6°, 25.5°, and 28.2° in CuKα characteristic X-ray diffraction, chlorogallium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 6.8°, 17.3°, 23.6°, and 26.9°, and chlorogallium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 8.7°, 9.2°, 17.6°, 24.0°, 27.4°, and 28.8°. As the hydroxygallium phthalocyanine, preferred are hydroxygallium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 7.3°, 24.9°, and 28.1° in CuKα characteristic X-ray diffraction, and hydroxygallium phthalocyanine crystals having strong peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3°.

[0025] Examples of the binder resin used in the charge generating layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenolic resins, melamine resins, silicon resins, and epoxy resins. Among these, polyester resins, polycarbonate resins, and polyvinyl acetal resins are preferred, and polyvinyl acetal is more preferred. In the charge generating layer, the ratio of the charge generating material to the binder resin (charge generating material / binder resin) is preferably in the range of 10 / 1 to 1 / 10, and more preferably in the range of 5 / 1 to 1 / 5. Examples of the solvent used in the coating liquid for the charge generating layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon solvents. The thickness of the charge generating layer is preferably from 0.05 μm to 5 μm.

[0026] <Charge transport layer> The charge transport layer is obtained by preparing a coating liquid for the charge transport layer by dissolving or dispersing a charge transport material and, if necessary, a binder resin in a solvent, forming a coating film of the coating liquid for the charge transport layer, and drying the coating film. When a protective layer, which will be described later, is not provided, the charge transport layer becomes the surface layer of the photosensitive drum. Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. Also, polymers having groups derived from these compounds in the main chain or side chain are also included. Among these, the charge transport material is preferably a triarylamine compound, a styryl compound, or a benzidine compound, and particularly preferably a triarylamine compound. Also, the charge transport material can be used alone or in a mixture of one or more kinds. Examples of the binder resin used in the charge transport layer include resins (insulating resins) such as polyvinyl butyral resin, polyvinyl acetal resin, polyester resin, polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, polyvinyl acetate resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin. Organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinylpyrene can also be used.

[0027] <Protective layer> On the photosensitive layer, a protective layer may be provided directly on the charge transport layer as necessary for durability, charging ability, etc. The protective layer is obtained by dissolving a resin in an organic solvent to prepare a coating liquid for the protective layer, forming a coating film of the coating liquid for the protective layer, and drying it. The protective layer can also be formed by curing the coating film by heating, electron beams, ultraviolet rays, etc. Resins used in the protective layer include polyvinyl butyral resins, polyester resins, polycarbonate resins (such as polycarbonate Z resins and modified polycarbonate resins), nylon resins, polyimide resins, polyarylate resins, polyurethane resins, styrene-butadiene copolymers, styrene-acrylic acid copolymers, styrene-acrylonitrile copolymers, and melamine-guanamine resins. In order to provide the protective layer with a charge transporting function, the protective layer may be formed by curing a monomer having a charge transporting function using various polymerization reactions or crosslinking reactions. Specifically, it is preferable to form the protective layer by polymerizing or crosslinking a charge transporting compound having a chain polymerizable functional group and curing it. The protective layer may also contain conductive particles, ultraviolet absorbers, lubricants such as fluorine-containing resin particles, etc. The conductive particles may be, for example, metal oxide particles such as tin oxide particles. The thickness of the protective layer is preferably 0.05 to 20 μm. The coating method for each layer may be a dip coating method (dipping method), a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, etc. Among these, the dip coating method is preferred from the viewpoints of efficiency and productivity. In the present invention, the resin used in the outermost layer (protective layer, or charge transport layer when there is no protective layer) of the photosensitive drum is preferably a polyester resin or a polycarbonate resin.

[0028] <Polyester resin> A particularly preferred polyester resin structure in the present invention has a carboxylic acid moiety represented by general formula (1) and a diol moiety represented by general formula (2). [ka] [ka] (X 1 represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. X 2 represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R 21 ~R 28 each independently represents a hydrogen atom or an alkyl group.

[0029] Examples of the structure represented by general formula (1) possessed by the polyester resin include structures derived from carboxylic acids such as terephthalic acid, isophthalic acid, biphenyldicarboxylic acid, aliphatic dicarboxylic acid, and naphthalenedicarboxylic acid. Specific examples include the following structures (1-1) to (1-5). Among these, the structure represented by (1-1) or (1-4) is more preferred. [ka]

[0030] Specific examples of the structure represented by general formula (2) include the following structures (2-1) to (2-14). Among these, linear or cyclic structures such as those represented by (2-3) and (2-11) are preferred. [ka] [ka]

[0031] <Polycarbonate resin> A particularly preferred polycarbonate resin structure in the present invention has the following structural formula (3). [ka] X 3 represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R 31 ~R 38 each independently represents a hydrogen atom or an alkyl group.

[0032] Specific examples of the structural unit of the polycarbonate resin represented by the formula (3) are shown below. [ka]

[0033] These binder resins may be used alone or in combination of two or more as a mixture or copolymer. The copolymer form may be any of block copolymer, random copolymer, alternating copolymer, etc. Furthermore, the molecular weight of these is preferably in the range of weight average molecular weight (Mw) = 10,000 to 300,000. These polycarbonate resins and polyester resins can be synthesized by known methods, for example, the methods described in JP-A-2007-047655 and JP-A-2007-072277. EXAMPLES

[0034] The present invention will be described in more detail below with reference to specific examples. In the following, "parts" refers to "parts by mass". However, the present invention is not limited to these. The film thickness of each layer of the photosensitive drum in the examples and comparative examples was determined by a method using an eddy current film thickness meter (Fischerscope, manufactured by Fisher Instruments), a method using a spectroscopic interference film thickness meter (C-13027-11, manufactured by Hamamatsu Photonics), or a method of converting the mass per unit area into specific gravity.

[0035] [Photosensitive drum manufacturing example] [Photosensitive drum manufacturing example 1] (Support) A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as a support (conductive support). It was ultrasonically cleaned in a cleaning solution of pure water containing detergent (product name: Chemicol CT, Tokiwa Chemical Co., Ltd.), and then the cleaning solution was washed away. It was further ultrasonically cleaned in pure water and degreased, and this was used as a support.

[0036] (Conductive layer) Zinc oxide particles (specific surface area: 19 m 2 / g, powder resistance: 4.7×10 6 100 parts of the solubility in water (Ω·cm) was stirred and mixed with 500 parts of toluene, to which 0.8 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, product name: KBM602, Shin-Etsu Chemical Co., Ltd.) was added and stirred for 6 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles A. Next, 15 parts of butyral (product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 15 parts of blocked isocyanate (product name: Duranate TPA-B80E, non-volatile content 80% by mass, manufactured by Asahi Kasei Chemicals Co., Ltd.) were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. 80.8 parts of surface-treated zinc oxide particles A and 0.81 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to this solution, and the mixture was dispersed in a sand mill device using glass beads with a diameter of 0.8 mm under an atmosphere of 23±3°C for 3 hours. After the dispersion treatment, 0.01 parts of silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (formerly Toray Dow Corning Silicones Co., Ltd.)) and 5.6 parts of cross-linked polymethyl methacrylate (PMMA) particles (product name: Techpolymer SSX-103, manufactured by Sekisui Chemical Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer. The obtained coating liquid for undercoat layer was dip-coated onto the support to form a coating film, and the coating film was dried at 160° C. for 30 minutes to form a conductive layer having a thickness of 18 μm.

[0037] (Charge generation layer) Four parts of hydroxygallium phthalocyanine crystals (charge generating material) having strong peaks at Bragg angles 2θ±0.2° at 7.4° and 28.1° in CuKα characteristic X-ray diffraction, and 0.04 parts of a compound represented by the following formula (E) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. The solution was then dispersed for 1 hour in an atmosphere of 23±3°C using a sand mill using glass beads with a diameter of 1 mm, and after the dispersion treatment, 100 parts of ethyl acetate was added to prepare a coating solution for a charge generating layer. This charge generating layer coating liquid was dip coated onto the undercoat layer, and the resulting coating was dried at 90° C. for 10 minutes to form a charge generating layer having a thickness of 0.15 μm. [ka]

[0038] (charge transport layer) A coating solution for a charge transport layer was prepared by dissolving 60 parts of a compound represented by the following formula (F), 30 parts of a compound represented by the following formula (G), 10 parts of a compound represented by the following formula (H), 100 parts of a bisphenol Z-type polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation), and 0.2 parts of a polycarbonate having a structural unit represented by the following formula (I) (viscosity average molecular weight Mv: 20,000) in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane. This charge transport layer coating liquid was dip coated onto the charge generating layer to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer having a thickness of 18 μm. [ka] [ka] [ka] [ka] (In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0039] (protective layer) A dispersant solution was prepared by dissolving 2.8 parts of a graft copolymer represented by the following formula (A-1) in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (product name: AE-3000, manufactured by AGC Corporation) and 100 parts of 1-propanol. 40 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average circularity 0.85) were added to the obtained dispersant solution, and the mixture was passed through a high-pressure disperser (product name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a polytetrafluoroethylene resin particle dispersion. To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of a hole transporting compound represented by the following formula (B), 21.9 parts of a compound represented by the following formula (C), and 100 parts of 1-propanol were added. Then, the mixture was filtered with a Polyflon filter (product name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating liquid for protective layer). [ka] [ka] [ka] This protective layer coating solution was applied by dip coating on the charge transport layer to form a coating film, and the resulting coating film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under a nitrogen atmosphere at an acceleration voltage of 70 kV and an absorbed dose of 15 kGy. Then, in a nitrogen atmosphere, heat treatment was performed for 15 seconds under conditions such that the temperature of the coating film reached 135°C. The oxygen concentration from the irradiation of the electron beam to the heat treatment for 15 seconds was 15 ppm. Next, the coating film was naturally cooled in the atmosphere until the temperature reached 25°C, and then heat treatment was performed for 1 hour under conditions such that the coating film reached 105°C, forming a surface layer (protective layer) with a thickness of 5 μm. In this manner, a photosensitive drum 1 having a support and a surface layer before surface polishing was prepared.

[0040] <Surface treatment of photosensitive drum> The surface of the photosensitive drum before surface polishing was provided with a circumferentially striped surface shape. Both ends of the photosensitive drum before surface polishing were gripped, the drum was rotated in the circumferential direction, and polished by pressing an abrasive sheet against it. Riken Corundum Co., Ltd.'s GC3000 abrasive sheet was used.

[0041] The surface shape of the photosensitive drum after surface polishing was measured. The maximum height Rmax according to JIS B 0601 1982 was measured using a surface roughness measuring instrument, Surfcorder SE3500, manufactured by Kosaka Laboratory Co., Ltd., and the Rmax was 0.75 μm.

[0042] [Photosensitive drum manufacturing example 2] Photosensitive drum 2 was obtained in the same manner as in Photosensitive drum Production Example 1, except that the protective layer was changed as follows and the surface treatment was not performed.

[0043] (protective layer) A coating solution for a surface protective layer was prepared by mixing and dissolving 5 parts of a compound having a guanamine structure and represented by the following formula (A)-15, 63 parts of a compound represented by the following formula (I-16) as a charge transport material, 27 parts of a compound represented by the following formula (I-8), 5 parts of a butyral resin as a binder resin, 1 part of 3,5-di-t-butyl-4-hydroxytoluene as an antioxidant, 0.15 parts of dodecylbenzenesulfonic acid, 80 parts of isobutyl alcohol, and 80 parts of cyclopentanol. This surface protection layer coating liquid was dip-coated onto the charge transport layer to form a coating film, and the resulting coating film was air-dried at room temperature for 30 minutes and then hardened by heat treatment at 150°C for 1 hour to form a surface protection layer with a thickness of 5 μm, thereby obtaining photosensitive drum 2. [ka] [ka]

[0044] [Photosensitive drum manufacturing example 3] Photosensitive drum 3 was obtained in the same manner as in Photosensitive Drum Preparation Example 1, except that no protective layer was provided, no surface treatment was performed, and the charge transport layer was changed as follows.

[0045] (charge transport layer) A coating liquid for a charge transport layer was prepared by dissolving 100 parts of a polyester resin (binder resin, weight average molecular weight: 40,000) having structural units represented by the above formulae (1-2), (1-3), and (2-3) shown in Table 1 in a mixed solvent of 360 parts of o-xylene, 160 parts of methyl benzoate, and 270 parts of dimethoxymethane. This coating liquid for a charge transport layer was dip-coated on the charge generating layer to form a coating film, and the coating film was dried at 120° C. for 60 minutes to form a charge transport layer with a thickness of 35 μm.

[0046] [Photosensitive drum manufacturing examples 4 to 6] Photosensitive drums 4 to 6 were obtained in the same manner as in Photosensitive Drum Preparation Example 3, except that the charge transport layer was changed to a polyester resin shown in Table 1.

[0047] [Table 1]

[0048] [Photosensitive drum manufacturing examples 7-9] Photosensitive drums 7 and 8 were obtained in the same manner as in Photosensitive Drum Preparation Example 3, except that the charge transport layer was changed to a polycarbonate resin shown in Table 2.

[0049] [Table 2]

[0050] [Example 1] A modified machine was used, in which the solid-state exposure mechanism described in the above example was provided in a portion of the imageRUNNER ADVANCE C5870F (registered trademark) multifunction printer manufactured by Canon Inc., where the exposure unit had been removed. In evaluating the invention, a cleaning member as shown in Fig. 3 was prepared, and the material of the rubbing surface of the drum rubbing unit 402 provided on the surface facing the photosensitive drum 103 side as shown in Fig. 4 was a nylon nonwoven fabric. When the polarity of the rubbing surface of this drum rubbing unit was confirmed using the above-mentioned method, it was confirmed that it was negatively charged. The drum rubbing part for the lens array cleaning rod prepared as described above and the photosensitive drum manufactured in the example shown in Photosensitive Drum Manufacturing Example 1 were evaluated for adhesion, drum scratches, and images in a normal temperature and low humidity environment (temperature 23°C, relative humidity 15%). The results are shown in Table 3.

[0051] (Adhesion evaluation) In this evaluation example, 1,000 sheets were passed through the multifunction printer with the photosensitive drum installed, and then the lens array was wiped 10 times while scrubbing the photosensitive drum with a lens array cleaning stick.The photosensitive drum was then removed from the multifunction printer, and any adhesions on the surface of the photosensitive drum were observed. To observe the deposits on the photosensitive drum surface, a halogen lamp was used as the inspection light and an 8192-pixel line sensor (Keyence Corporation: XG-HL08M) was used as the imaging means. The inspection light was set at a 45° angle to the normal line of the photosensitive drum, and the line camera was set at a 45° angle symmetrical to the inspection light with respect to the normal line. The photosensitive drum was rotated at a speed of 60 rpm, and the regular reflection light was captured, obtaining an image with a resolution of 44 μm / pixel. This image was smoothed using a small smoothing filter, and the difference between the image smoothed using a large smoothing filter was obtained to obtain an image in which the global gradation was removed from the small smoothed image. Next, binarization was performed with a white threshold of 20 and a black threshold of -25, and points with a white or black area of ​​20 pix x 20 pix or more were considered to be adhesions, and the number of defects on the entire surface was counted. The number of counted defects was evaluated according to the following evaluation criteria A to C. If the evaluation result was C or higher, it could be determined that the effects of the present invention were obtained. A: 3 or fewer defects in the entire field of view B: More than 3 defects and up to 10 defects in the entire field of view C: More than 10 defects but no more than 30 defects in the entire field of view D: More than 30 defects in the entire field of view

[0052] (Drum scratch evaluation) After the evaluation of adhesion, the drum was passed through the multifunction printer 10,000 times, and then the photosensitive drum was removed from the multifunction printer, and scratches on the surface of the photosensitive drum were observed under a microscope. A: No scratches, or only minor scratches. B: There are scratches of up to 3 μm in size, but the output image is not affected. C: The scratches reach 3 μm or more and affect the output image.

[0053] [Examples 2 to 13, Comparative Examples 1 to 3] For Example 1, evaluation was performed on combinations of the material of the sliding surface of the drum sliding portion, the photosensitive drum, and the resin of the outermost layer of the photosensitive drum, as shown in Table 3 below. The results are shown in Table 3.

[0054] [Table 3]

[0055] The disclosure of this embodiment includes the following configuration. [Configuration 1] A photosensitive drum rotatable around a rotation axis; a plurality of light emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting elements and a light exit surface facing the photosensitive drum, the lens array being configured so that a plurality of lenses for converging the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum are arranged in the direction of the rotation axis; a cleaning member that is inserted between a surface of the photosensitive drum and the light emission surface of the lens array, and cleans the light emission surface of the lens array while rubbing the surface of the photosensitive drum and the light irradiation surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having the cleaning member has a rubbing portion having a rubbing surface that is caused to rub against the surface of the photosensitive drum, the sliding surface that slides against the surface of the photosensitive drum is made of at least one material selected from the group consisting of nylon and materials that are more likely to be negatively charged than nylon; 1. An image forming apparatus comprising: [Configuration 2] 2. The image forming apparatus according to claim 1, wherein the surface of the photosensitive drum is made of at least one material selected from the group consisting of rayon and materials that are more likely to be negatively charged than rayon. [Configuration 3] 3. The image forming apparatus according to claim 1, wherein the rubbing surface that is caused to rub against the surface of the photosensitive drum includes at least one material selected from the group consisting of rayon, polyester, and polyurethane. [Configuration 4] 4. The image forming apparatus according to any one of configurations 1 to 3, wherein the rubbing surface that is caused to rub against the surface of the photosensitive drum contains polyester. [Configuration 5] 4. The image forming apparatus according to any one of configurations 1 to 3, wherein the rubbing surface that is caused to rub against the surface of the photosensitive drum contains polyurethane. [Configuration 6] 6. The image forming apparatus according to any one of configurations 1 to 5, wherein the photosensitive drum contains, as a binder resin, a resin having units having structures represented by the following formulas (1) and (2): [ka] [ka] (X 1 represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. X 2 represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R 21 ~R 28 each independently represents a hydrogen atom or an alkyl group. [Configuration 7] 7. The image forming apparatus according to any one of configurations 1 to 6, wherein the photosensitive drum contains a resin having a structure represented by the following formula (3) as a binder resin: [ka] (X 3 represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R 31 ~R 38 each independently represents a hydrogen atom or an alkyl group. [Configuration 8] A photosensitive drum rotatable around a rotation axis; a plurality of light emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incidence surface facing the light emitting elements and a light emission surface facing the photosensitive drum, the lens array being configured by arranging a plurality of lenses in the direction of the rotation axis for converging the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum; a cleaning member that is inserted between a surface of the photosensitive drum and the light emission surface of the lens array, and cleans the light emission surface of the lens array while rubbing the surface of the photosensitive drum and the light irradiation surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having the cleaning member has a rubbing portion having a rubbing surface that is caused to rub against the surface of the photosensitive drum, The image forming apparatus is characterized in that a sliding surface which slides against the surface of the photosensitive drum is made of at least one material selected from the group consisting of nylon, rayon, polyester and polyurethane. [Explanation of symbols]

[0056] 103 Photosensitive drum 201 Solid-state exposure head 202 Light emitting substrate 206 Lens Array 300 Cleaning means 401 Cleaning materials 402 Drum sliding part 701 Support 702 Undercoat layer 703 Charge generation layer 704 Charge transport layer

Claims

1. A photosensitive drum rotatable around a rotation axis; a plurality of light emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting elements and a light exit surface facing the photosensitive drum, the lens array being configured so that a plurality of lenses for converging the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum are arranged in the direction of the rotation axis; a cleaning member that is inserted between a surface of the photosensitive drum and the light emission surface of the lens array, and cleans the light emission surface of the lens array while rubbing the surface of the photosensitive drum and the light irradiation surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having the cleaning member has a rubbing portion having a rubbing surface that is caused to rub against the surface of the photosensitive drum, The sliding surface that slides against the surface of the photosensitive drum is made of at least one material selected from the group consisting of nylon and materials that are more likely to be negatively charged than nylon.

1. An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the sliding surface that slides against the surface of the photosensitive drum is made of at least one material selected from the group consisting of rayon and materials that are more likely to be negatively charged than rayon.

3. 2. The image forming apparatus according to claim 1, wherein the rubbing surface that rubs against the surface of the photosensitive drum includes at least one selected from the group consisting of rayon, polyester, and polyurethane.

4. 2. The image forming apparatus according to claim 1, wherein the rubbing surface that rubs against the surface of the photosensitive drum contains polyester.

5. 2. The image forming apparatus according to claim 1, wherein the sliding surface that slides against the surface of the photosensitive drum contains polyurethane.

6. 6. The image forming apparatus according to claim 1, wherein the photosensitive drum contains, as a binder resin, a resin having units having structures represented by the following formulas (1) and (2): 【Chemistry 1】 【Chemistry 2】 (X １ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. X ２ represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R ２１ ~R ２８ each independently represents a hydrogen atom or an alkyl group.

7. 6. The image forming apparatus according to claim 1, wherein the photosensitive drum contains a resin having a structure represented by the following formula (3) as a binder resin: 【Chemistry 3】 (X ３ represents a single bond, an oxygen atom, an alkylidene group, or a cycloalkylidene group. R ３１ ~R ３８ each independently represents a hydrogen atom or an alkyl group.

8. A photosensitive drum rotatable around a rotation axis; a plurality of light emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incidence surface facing the light emitting elements and a light emission surface facing the photosensitive drum, the lens array being configured by arranging a plurality of lenses in the direction of the rotation axis for converging the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum; a cleaning member that is inserted between a surface of the photosensitive drum and the light emission surface of the lens array, and cleans the light emission surface of the lens array while rubbing the surface of the photosensitive drum and the light irradiation surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having the cleaning member has a rubbing portion having a rubbing surface that is caused to rub against the surface of the photosensitive drum, The image forming apparatus is characterized in that a sliding surface which slides against the surface of the photosensitive drum is made of at least one material selected from the group consisting of nylon, rayon, polyester and polyurethane.

Images