Electrophotographic device

Abstract

To solve the problem in which: unevenness occurs between a portion rubbed by a cleaning member and a portion not rubbed by the cleaning member.SOLUTION: An image forming apparatus has photoconductor drum protective agent supply means, light-emitting devices, a lens array, and a cleaning member for cleaning, while rubbing, a light emission surface of the lens array. The cleaning member has a drum rubbing part that rubs a surface of the photoconductor drum. The rubbing surface has lubricant. The difference between the refractive index of a protective agent and the refractive index of the lubricant is 0.15 or less.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an electrophotographic apparatus.

Background Art

[0002] In an electrophotographic image forming apparatus such as a laser beam printer or a digital copying machine, as one means for exposing a photosensitive drum, an exposure head that exposes the photosensitive drum all at once in the main scanning direction is known. In this exposure head, a plurality of light emitting elements such as a large number of LEDs or organic ELs are arranged in a substantially straight line in a direction parallel to the rotation axis of the photosensitive drum (main scanning direction). An exposure apparatus using this exposure head method has a smaller volume of the entire exposure apparatus compared to a laser scanning type exposure apparatus that performs scanning using a polygon mirror. Also, when using a polygon mirror, there is no necessary drive unit. Therefore, it is advantageous for miniaturization and low noise of the image forming apparatus.

[0003] An LED exposure head using an LED as a light emitting element includes a lens array in which a plurality of refractive index distribution type 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 LED on the photosensitive drum. Since the focal length of this lens array is extremely short, it is necessary to arrange the LED exposure head very close to the photosensitive drum. On the other hand, in the vicinity of the photosensitive drum, toner and foreign matter may float along with the air flow for internal cooling of the image forming apparatus. When such toner and foreign matter adhere to the emission surface of the lens array, the amount of light irradiating the photosensitive drum becomes non-uniform and defective images such as density unevenness occur. For this reason, cleaning means for cleaning the surface of the lens array is required in the LED exposure head.

[0004] As an example of the cleaning means, as shown in Patent Document 1, there is known a means for cleaning the lens array in a form in which a guide portion for controlling the distance between the photosensitive drum and the cleaning member is provided to guide. However, in an image forming apparatus in which the mounting density of internal units is increased for the purpose of miniaturization, it may be difficult to provide such a guide portion in the vicinity of the LED exposure head. As a method for meeting the downsizing of internal units, Patent Document 2 discloses a means for cleaning the surface of a lens array while providing a protection member for an electrophotographic photosensitive drum on the surface of the cleaning member facing the photosensitive drum and bringing the protection member into contact with the photosensitive drum.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the case of a configuration in which the lens array cleaning member is sandwiched between the lens array and the photosensitive drum and the lens array is cleaned while bringing the photosensitive drum into contact with the drum rubbing portion, the following problems exist. In this configuration, the lens array cleaning member rubs against the lens array and the photosensitive drum, but on the photosensitive drum, the surface characteristics of the photosensitive drum change between the rubbed portion and the non-rubbed portion. As a result, uneven exposure occurs when the photosensitive drum is irradiated with an LED exposure head, and image defects such as density unevenness occur. The image forming apparatus of Patent Document 3 has a cleaning blade for recovering residual toner on the photosensitive drum. And in order to maintain the cleaning performance of the cleaning blade, a lubricant is applied to the surface of the photosensitive drum. When a lubricant is applied to the photosensitive drum in this way, unevenness may occur between the rubbed portion and the non-rubbed portion.

Means for Solving the Problems

[0007] The above problems are solved by the following present disclosure. That is, a photosensitive drum rotatable about a rotation axis, and A photosensitive drum protector supply means having a protective agent and applying or adhering the protective agent to the surface of the photosensitive drum when the photosensitive drum rotates, A plurality of light-emitting elements for emitting exposure light irradiated on 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, in which a plurality of lenses for condensing the exposure light emitted from the light-emitting element on the surface of the photosensitive drum are arranged in the direction of the rotation axis, A cleaning member inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and cleaning the light exit surface of the lens array while rubbing the surface of the photosensitive drum and the light exit 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 drum rubbing portion that rubs against the surface of the photosensitive drum, The drum rubbing portion has a lubricant, The difference between the refractive index of the protective agent and the refractive index of the lubricant is 0.15 or less, An image forming apparatus characterized by this.

[0008] Or, A photosensitive drum rotatable about a rotation axis, A photosensitive drum protector supply means having a protective agent and applying or adhering the protective agent to the surface of the photosensitive drum when the photosensitive drum rotates, A plurality of light-emitting elements for emitting exposure light irradiated on 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, in which a plurality of lenses for condensing the exposure light emitted from the light-emitting element on the surface of the photosensitive drum are arranged in the direction of the rotation axis, A cleaning member inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and cleaning the light exit surface of the lens array while rubbing the surface of the photosensitive drum and the light exit 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 drum rubbing portion that rubs against the surface of the photosensitive drum, the image forming apparatus has a cleaning member lubricant supply means for applying or adhering a lubricant to the drum rubbing portion before the cleaning member rubs against the surface of the photosensitive drum and the light emitting surface of the lens array, the difference between the refractive index of the protective agent and the refractive index of the lubricant is 0.15 or less, An image forming apparatus characterized by the above.

Advantages of the Invention

[0009] According to the present disclosure, unevenness in the amount of lubricant applied to the surface at the portion where the drum rubbing portion rubs and the portion where it does not rub on the photosensitive drum is suppressed, and the occurrence of image defects such as density unevenness can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described in detail with reference to preferred embodiments. Image forming apparatus FIG. 1A shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge. The electrophotographic apparatus includes four image forming units 102Y, 102M, 102C, and 102K that form toner images of yellow, magenta, cyan, and black colors. The image forming units 102Y, 102M, 102C, and 102K each include a photosensitive drum 103Y, 103M, 103C, and 103K. Around the photosensitive drums, there are chargers 104Y, 104M, 104C, and 104K, solid (LED) exposure heads 105Y, 105M, 105C, and 105K, developing devices 106Y, 106M, 106C, and 106K, and drum cleaning members 108Y, 108M, 108C, and 108K in which a protective agent supply means (also referred to as a photosensitive drum protective agent supply means) for supplying a protective agent to the photosensitive drum and a drum cleaning means are integrated.

[0012] <Image forming process> The photosensitive drums 103Y, 103M, 103C, and 103K uniformly charged by the chargers 104Y, 104M, 104C, and 104K are exposed by the LED exposure heads 105Y, 105M, 105C, and 105K to form electrostatic latent images. The electrostatic latent images are visualized as toner images of their respective colors by the developing devices 106Y, 106M, 106C, and 106K and transferred to the intermediate transfer belt 107 in the primary transfer units Ty, Tm, Tc, and Tk. The toner images of respective colors superimposed on the intermediate transfer belt 107 are collectively transferred onto a recording paper P conveyed from the paper feeding unit 101 by a secondary transfer roller 109 in the secondary transfer unit T2. The recording paper P onto which the toner image has been transferred is conveyed to a fixing unit 110, the toner image is fixed by heat and pressure, and then discharged from a paper discharging unit 111.

[0013] <Photosensitive drum protective agent supply means> FIG. 1B shows an example of the schematic configuration of a process cartridge including the photosensitive drum of the present disclosure. The photosensitive drum 103 is rotatable about the axis of rotation, that is, it rotates about the rotation shaft 10. The axis of rotation is a line perpendicular to the plane of the paper in the rotation shaft 10, that is, the direction of the axis of rotation refers to the direction perpendicular to the plane of the paper. A drum cleaning member 108 in which a protective agent supply means 108a for supplying a protective agent to the photosensitive drum and a drum cleaning means 108b are integrated applies a protective agent to the surface of the photosensitive drum 103. The protective agent is supplied to the surface of the photosensitive drum during the rotation of the photosensitive drum from a protective agent supply means 108a composed of a member in which a melted and solidified protective agent is attached to a metal plate. The supplied protective agent is spread on the photosensitive drum by a cleaning blade which is the drum cleaning means 108b downstream in the rotation direction of the photosensitive drum. The drum cleaning means 108b is also a means for spreading the protective agent and is also referred to as a protective agent leveling member.

[0014] <Exposure device> FIG. 2 shows a cross-sectional view of the LED exposure head 105 as an example. The housing 205 includes a light-emitting element substrate 202 on which light-emitting elements 203 are arranged and a lens array 206. On the light-emitting element substrate 202, LED chips which are a plurality of light-emitting elements are arranged in the main scanning direction (the direction of the axis of rotation of the photosensitive drum). The lens array is composed of a plurality of cylindrical refractive index distribution type lenses. The lens array has a light incident surface facing the light-emitting element and a light exit surface facing the photosensitive drum, and each lens condenses the exposure light emitted from the light-emitting element 203 on the surface of the photosensitive drum. The plurality of lenses are arranged in the main scanning direction in the same manner as the light-emitting elements to form the lens array 206. That is, the longitudinal direction of the lens array is the main scanning direction (the direction of the axis of rotation of the photosensitive drum). The material of the housing 205 is a zinc-plated steel sheet or a sheet material obtained by subjecting a cold-rolled steel sheet to a plating treatment later. The lens array 206 forms an image of the light beam emitted from the light-emitting element 203 on the photosensitive drum 103 as an equal-magnification erect image. At this time, the distance from the light-emitting element to the light incident surface of the lens array 206 and the distance from the light exit surface of the lens array 206 to the surface of the photosensitive drum 103 are substantially equal. The distance between the light-emitting element 203 and the light incident surface of the lens array 206 requires high precision on the order of μm. After precisely adjusting this distance, the light-emitting element substrate 202 and the lens array 206 are fixed to the housing 205 by adhesion. In this example, an LED is used as the light-emitting element 203, and an integrated unit of the light-emitting element substrate 202, the lens array 206, and the housing 205 is referred to as the LED exposure head 105.

[0015] <Lens array cleaning mechanism> As described above, when toner or foreign matter adheres to the light-emitting surface of the lens array 206, it partially blocks the light emitted from the light-emitting element, resulting in a deterioration in the image quality of the output image. Therefore, the light-emitting surface of the lens array 206 needs to be cleaned regularly. The lens array cleaning member 300 (the lens array cleaning member is also simply referred to as the cleaning member) is inserted between the surface of the photosensitive drum and the light-emitting surface of the lens array 206, and while rubbing the surface of the photosensitive drum and the light-emitting surface of the lens array 206 from one end side to the other end side in the longitudinal direction of the lens array 206, the lens array 206 is cleaned. FIG. 3 is an example of an overall view of the lens array cleaning member 300 of the LED exposure head 105 used in the present disclosure. The lens array cleaning member 300 is generally elongated and rod-shaped, having a gripping portion 302 at one end of the rod-shaped body portion 303 and a cleaning portion 301 at the other end. The body portion 303 is formed of an engineering plastic such as ABS or PP, for example.

[0016] <Lens array rubbing portion and drum rubbing portion> FIG. 4 shows a state in which the lens array cleaning member 300 is inserted between the surface of the photosensitive drum and the light emitting surface of the lens array 206. The cleaning unit 301 includes a lens array rubbing portion 401 on the surface facing the lens array 206 and a drum rubbing portion 402 on the surface facing the photosensitive drum 103 side in a state where the lens array cleaning member 300 is inserted. The lens array rubbing portion 401 wipes the lens array emission surface with the tip of a blade formed of a material such as urethane rubber to remove toner and foreign matter. Other materials such as silicon rubber and chloroprene rubber may also be used. Also, a configuration in which a non-woven fabric or felt is selected instead of a blade for cleaning is also conceivable. The drum rubbing portion 402 is composed of at least one material selected from the group consisting of a woven fabric, a non-woven fabric, a rubber member, and a brush. Specifically preferred members include, in the case of a non-woven fabric or a brush, members made of nylon (polyamide), rayon, polyester, and polyurethane. Among these, polyester and polyurethane are preferred. Examples of the rubber member include silicon rubber, chloroprene rubber, and urethane rubber. Among these, polyurethane rubber is preferred. The material of the drum rubbing portion 402 may use only one material, or may use two or more materials as a mixture or copolymer.

[0017] <Supply of Lubricant to Drum Rubbing Portion> The drum rubbing portion 402 contains a lubricant. The lubricant is impregnated or applied to the drum rubbing portion 402 in advance. Alternatively, the drum rubbing portion 402 is impregnated or applied with the lubricant immediately before the lens array rubbing portion 401 cleans the lens array 206 by the cleaning member lubricant supply means. FIG. 5 shows an example of a cleaning member lubricant supply means for more stably supplying a lubricant to the drum rubbing portion 402. At the upper part of the insertion port 502 of the drum rubbing part 402, a solid bar containing a lubricant component is installed as the lubricant supply means 501 at a position where the drum rubbing part 402 rubs when the lens array cleaning member 300 is inserted. When the lens array cleaning member 300 is inserted into the insertion port 502 of the main body for cleaning, the drum rubbing part 402 is inserted while rubbing against the solid bar, so that the lubricant is supplied to the drum rubbing part 402.

[0018] [Photosensitive drum] As an example of the photosensitive drum 103 used in the present disclosure, a support and a laminated photosensitive layer formed on the support are shown in FIG. 6. In FIG. 6, 601 is a support, 602 is an undercoat layer, 603 is a charge generation layer, 604 is a charge transport layer, and 605 is a protective layer.

[0019] [Support] As the support, those having conductivity (conductive supports) are preferable. For example, supports made of metals (alloys) such as aluminum, iron, copper, gold, stainless steel, nickel, etc., supports of metals with a conductive film provided on the surface, supports of insulators, etc. can be mentioned. Examples of the insulator support include plastics such as polyester resin, polycarbonate resin, polyimide resin, glass, and paper supports. Examples of the conductive film include metal thin films such as aluminum, chromium, silver, and gold, thin films of conductive materials such as indium oxide, tin oxide, and zinc oxide, and thin films of conductive ink containing silver nanowires. The surface of the support may be subjected to electrochemical treatments such as anodic oxidation, blasting treatments, cutting treatments, etc. Examples of the shape of the support include a cylindrical shape and a film shape. Among these, a cylindrical aluminum support is excellent in terms of mechanical strength, electrophotographic characteristics, and cost. Also, the bare tube may be used as the support, but those obtained by subjecting the surface of the bare tube to physical treatments such as cutting, honing, blasting, etc., anodic oxidation treatment, chemical treatment using an acid, etc. for improving electrical characteristics and suppressing interference fringes may be used as the support.

[0020] [Conductive layer] The conductive layer is a layer that may be provided if necessary. The conductive layer may be disposed on the conductive support and between the conductive support and the photosensitive layer, more specifically, in the layer sequence of conductive support / conductive layer / undercoat layer / photosensitive layer. By providing the conductive layer, it is possible to conceal scratches and unevenness on the surface of the conductive support and to control the reflection of light on the support surface. The conductive layer contains conductive particles and a resin. Examples of the material of the conductive particles include metal oxides, metals, carbon black, etc. Examples of the metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, bismuth oxide, etc. Among them, examples of the metal include aluminum, nickel, iron, chromium, copper, zinc, silver, etc. Among the above materials of the conductive particles, metal oxides are preferred, and particularly, 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 may be doped with an element itself such as phosphorus or aluminum or its oxide. Further, the conductive particles may have a laminated structure having a core material and a coating layer covering 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 above silane coupling agent are much thicker than the latter in terms of thickness. When using a metal oxide as the conductive particle, its volume average particle diameter is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0021] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, etc. Furthermore, the conductive layer may contain a concealer such as silicone oil, resin particles, titanium oxide, etc. The conductive layer can be obtained by providing a coating film of a coating liquid for a conductive layer containing each of the above materials and a 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, aromatic hydrocarbon-based solvents, etc. Examples of the dispersion method for dispersing conductive particles in the coating liquid for a conductive layer include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser. The average film thickness of the conductive layer is preferably 0.1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0022] <Undercoat layer> On the support or the conductive layer, an undercoat layer having a barrier function or an adhesion function may be provided as 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 has a resin and a substance for improving electrical properties. Each will be described. The undercoat layer contains a resin. Also, the resin may be obtained as a cured film in which a composition containing a monomer having a polymerizable functional group in the coating liquid is polymerized to form a coating film of the coating liquid (curing by polymerization of the monomer) as 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, cellulose resin, etc. Examples of the polymerizable functional groups of the monomers having polymerizable functional groups include isocyanate groups, blocked isocyanate groups, methylol groups, alkylated methylol groups, epoxy groups, metal alkoxide groups, hydroxyl groups, amino groups, carboxy groups, thiol groups, carboxylic anhydride groups, carbon-carbon double bond groups, and the like.

[0023] Further, the undercoat layer contains an electron transport material, a metal oxide, a metal, etc. for the purpose of improving electrical characteristics. Among these, it is preferable to use an electron transport material and a metal oxide. Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, boron-containing compounds, and the like. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the monomer having the above-mentioned polymerizable functional group to form an undercoat layer as a cured film. Examples of the metal oxide include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, strontium titanate, silicon dioxide, and the like. Examples of the metal include gold, silver, aluminum, and the like.

[0024] The metal oxide contained in the undercoat layer may be surface-treated using a surface treatment agent such as a silane coupling agent before use. As a method for surface-treating the metal oxide, a general method is used. For example, a dry method or a wet method can be mentioned. The dry method is to add an alcohol aqueous solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent while stirring the metal oxide in a mixer capable of high-speed stirring such as a Henschel mixer, uniformly disperse it, and then perform drying. Also, the wet method is to stir the metal oxide and the surface treatment agent in a solvent or disperse them using a sand mill or the like with glass beads or the like. After dispersion, the solvent is removed by filtration or distillation under reduced pressure. After removing the solvent, it is preferable to further perform baking at 100 °C or higher.

[0025] The undercoat layer may further contain an additive, and for example, known materials such as metal powders such as aluminum, conductive substances such as carbon black, metal chelate compounds, and organometallic compounds can be contained. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing each of the above materials and a solvent, forming this coating film 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 alcohol, sulfoxide, ketone, ether, ester, aliphatic halogenated hydrocarbon, and aromatic compound. In the present disclosure, it is preferable to use alcohol-based and ketone-based solvents. Examples of the dispersion method for preparing the coating solution for the undercoat layer include methods using a homogenizer, ultrasonic disperser, ball mill, sand mill, roll mill, vibration mill, attritor, and liquid collision type high-speed disperser. When using the undercoat layer, the average film thickness is preferably 0.05 μm or more and 50 μm or less, and more preferably 0.3 μm or more and 25 μm or less.

[0026] <Charge generation layer> A charge generation layer is provided directly above the undercoat layer. Examples of the charge generating material include phthalocyanine pigments such as perylene pigments, anthraquinone derivatives, anthraanthrone derivatives, dibenzopyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, indigo derivatives, thioindigo derivatives, metal phthalocyanines, and metal-free phthalocyanines, and bisbenzimidazole derivatives. Among these, at least one of an azo pigment and a phthalocyanine pigment is preferable. Among the phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine are preferable. As the oxytitanium phthalocyanine, a crystalline oxytitanium phthalocyanine crystal 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, or a crystalline oxytitanium phthalocyanine crystal 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° is preferred. As the chlorogallium phthalocyanine, a crystalline chlorogallium phthalocyanine crystal 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, or a crystalline chlorogallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 6.8°, 17.3°, 23.6° and 26.9°, or a crystalline chlorogallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 8.7°, 9.2°, 17.6°, 24.0°, 27.4° and 28.8° is preferred. As the hydroxygallium phthalocyanine, a crystalline hydroxygallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 7.3°, 24.9° and 28.1° in CuKα characteristic X-ray diffraction, or a crystalline hydroxygallium phthalocyanine crystal 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° is preferred.

[0027] Examples of the binder resin used in the charge generation layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, vinylidene fluoride, and trifluoroethylene, as well as polyvinyl alcohol resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenol resins, melamine resins, silicone 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 generation layer, the ratio of the charge generating substance to the binder resin (charge generating substance / 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. Solvents used in the coating solution for the charge generation layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, or aromatic hydrocarbon solvents. The film thickness of the charge generation layer is preferably 0.05 μm or more and 5 μm or less.

[0028] <Charge Transport Layer> The charge transport layer is obtained by dissolving or dispersing a charge transport substance and, if necessary, a binder resin in a solvent to prepare a coating solution for the charge transport layer, and forming and drying a coating film of the coating solution for the charge transport layer. When the protective layer described later is not provided, the charge transport layer becomes the surface layer of the photosensitive drum. Examples of the charge transport substance include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triallylmethane compounds. Also included are polymers having groups derived from these compounds in the main chain or side chain. Among these, triarylamine compounds, styryl compounds, or benzidine compounds are preferred as the charge transport substance, and triarylamine compounds are particularly preferred. The charge transport substance can be used alone or in combination of one or more. Examples of the binder resin used for 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, polyvinyl pyridine resin, cellulose-based resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin. Further, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinyl pyrene can also be used. The content of the charge transport material in the charge transport layer is preferably 20 to 80% by mass, more preferably 30 to 60% by mass, based on the total mass of the charge transport layer. The film thickness of the charge transport layer is preferably 5 μm or more and 40 μm or less.

[0029] <Protective layer> In the present disclosure, a protective layer may be provided on the photosensitive layer. By providing the protective layer, the durability can be improved. The protective layer is formed as a cured film by polymerizing, for example, a composition containing a monomer having a polymerizable functional group, which is a raw material of the binder material. Examples of the reaction at that time include a thermal polymerization reaction, a photopolymerization reaction, and a radiation polymerization reaction. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylmethylol group, an epoxy group, a metal alkoxyl group, a hydroxy group, an amino group, a carboxy group, a thiol group, a carboxylic anhydride group, and a group containing a carbon-carbon double bond. Examples of the group containing a carbon-carbon double bond include an acryloyl group and a methacryloyl group. As the monomer having a polymerizable functional group, a monomer having a charge transport ability may be used. Among these, as the monomer having a polymerizable functional group, from the viewpoint of mechanical durability, a monomer having three or more polymerizable functional groups in the molecule (a monomer having a trifunctional or higher polymerizable functional group) is preferable, and a UV-curable acrylic resin containing a trifunctional or higher radical polymerizable monomer is more preferable in terms of excellent abrasion resistance. Among these, a trifunctional to hexafunctional polymerizable compound is particularly preferable. By polymerizing the trifunctional or higher polymerizable compound, a three-dimensional network structure develops, and a high-hardness and high-elasticity protective layer with a very high crosslink density can be obtained, which is advantageous in terms of obtaining high abrasion resistance and scratch resistance. Examples of the monomer having a trifunctional or higher polymerizable functional group include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (EO-modified) triacrylate, trimethylolpropane propyleneoxy-modified (PO-modified) triacrylate, trimethylolpropane caprolactone-modified triacrylate, trimethylolpropane alkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, glycerol epichlorohydrin-modified (ECH-modified) triacrylate, glycerol EO-modified triacrylate, glycerol PO-modified triacrylate, tris(acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone-modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2,2,5,5,-tetrahydroxymethylcyclopentanone tetraacrylate, and the like. These may be used alone or in combination of two or more.

[0030] Further, lubricating particles such as conductive particles, silica particles, and fluorine atom-containing resin fine particles may be included in the protective layer. As the conductive particles, metal oxide particles such as aluminum oxide particles are preferable. The film thickness of the protective layer is preferably 0.05 to 20 μm. Further, a film thickness of 0.5 to 5.0 μm is preferable. As the coating method for each layer, coating methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, and beam coating method can be used. Among these, from the viewpoints of efficiency and productivity, the spray coating method and the dip coating method are preferable.

[0031] [Protective agent and lubricant] A lubricant is applied to the protective layer or the charge transport layer on the outermost surface to impart slipperiness to the surface. In the present disclosure, the lubricant supplied from the protective agent supply means 108a of the drum cleaning member 108 shown in FIG. 1B is distinguished as a "protective agent", and the lubricant applied to the photosensitive drum from the drum rubbing portion 402 of the lens array cleaning member 300 in FIG. 4 is distinguished as a "lubricant". The composition of the protective agent and the lubricant may be the same or different. As the protective agent or lubricant, there are inorganic lubricants and organic lubricants. As the organic lubricant, it is preferable to use a fatty acid metal salt. For example, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc stearate, zinc oleate, magnesium oleate, iron oleate, cobalt oleate, copper oleate, lead oleate, manganese oleate, zinc palmitate, cobalt palmitate, lead palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, lead caprylate, lead capric acid, zinc linolenate, cobalt linolenate, calcium linolenate, zinc ricinoleate, cadmium ricinoleate, zinc laurate, cobalt laurate, lead laurate, magnesium laurate, etc. may be mentioned. These may be used alone or in combination of two or more. Among these, from the viewpoint of excellent cleaning property, protectiveness of the photosensitive drum, low cost, and excellent hydrophobicity and being a very stable substance, fatty acid metal salts and lauric acid metal salts are preferable, and zinc stearate and zinc laurate are more preferable. Examples of the inorganic lubricant include mica, boron nitride, molybdenum disulfide, tungsten disulfide, talc, kaolin, montmorillonite, calcium fluoride, graphite, silicone resin, etc. These may be used alone or in combination of two or more. Among these, boron nitride is preferable.

[0032] The protective agent or lubricant preferably has a refractive index of 1.4 or more and 1.7 or less, and the difference in refractive index between the protective agent and the lubricant is preferably 0.15 or less. When the lens array of the exposure apparatus is rubbed and cleaned at the lens array rubbing portion, the lubricant is applied to the rubbing surface of the photosensitive drum by the drum rubbing portion. The protective agent is applied to the photosensitive drum by the protective agent supply means of the drum cleaning member. If the difference in refractive index between the applied lubricant and the protective agent is large, a difference in refractive index will occur between the contact portion where the drum rubbing portion hits and the non-contact portion where the drum rubbing portion does not hit due to the operation of the lens array cleaning member. As a result, unevenness in the amount of light hitting the photosensitive drum during exposure occurs, and image unevenness occurs. The difference in refractive index between the protective agent and the photosensitive drum is preferably 0.20 or less, and more preferably 0.15 or less. When the surface layer of the photosensitive drum contains a filler, exposure unevenness occurs due to the refractive index of the metal particles in the surface layer. If it is sufficiently covered with the protective agent, the refractive index of the protective agent becomes dominant and exposure unevenness can be suppressed. However, if the difference in refractive index between the protective agent and the photosensitive drum is large, the influence on the exposure amount when there is a difference in the coating amount of the protective agent becomes large, and exposure unevenness is likely to occur.

[0033] The coating amount of the protective agent on the photosensitive drum is preferably 0.0003 μg / mm 2 or more and 0.01 μg / mm 2 or less, and more preferably 0.003 μg / mm 2 or more and 0.006 μg / mm 2 or less. The coating film thickness of the protective agent is preferably 0.05 to 1.5 μm, and more preferably 0.5 to 1.0 μm. If the coating amount is too small, the slipperiness of the photosensitive drum cannot be obtained, which may cause toner leakage from the cleaning blade, which is a drum cleaning means. If the coating amount is too large, rubbing unevenness can occur during the rubbing of the drum by the drum rubbing portion of the lens array cleaning member. As a result, the rubbing unevenness causes exposure unevenness and image unevenness occurs. The coating amount of the protective agent can be calculated by dividing the mass (W) of the protective agent by the area (S) of the photosensitive drum. The mass (W) of the protective agent can be measured using an analytical balance (model name: AB204-S, manufactured by METTLER TOLEDO Co., Ltd.), and the area (S) of the photosensitive drum can be calculated using a micrometer or calipers.

Examples

[0034] Hereinafter, the present disclosure will be described in more detail using examples and comparative examples, but it is not limited thereto. In the description of the following examples, "parts" means based on mass unless otherwise specified. However, the present disclosure is not limited thereto. 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 thickness gauge (Fischerscope, manufactured by Fischer Instruments), a method using a spectroscopic interference thickness gauge (C-13027-11, manufactured by Hamamatsu Photonics), or a method of converting from the mass per unit area to specific gravity.

[0035] [Photosensitive drum] [Photosensitive drum 1] (Support) As the support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) that had been machined by cutting was used. Ultrasonic cleaning was performed in a cleaning solution containing a detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water. Subsequently, after flushing the cleaning solution away, ultrasonic cleaning was further performed in pure water for degreasing treatment, and this was used as the support.

[0036] (Undercoat layer) Zinc oxide particles (specific surface area: 19 m 2 / g, powder resistance: 4.7×10 6100 parts of Ω·cm were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Then, toluene was distilled off under reduced pressure, and the mixture was heated and dried at 130 °C for 6 hours to obtain surface-treated zinc oxide particles A. Subsequently, 15 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 15 parts of blocked isocyanate (trade name: Duranate TPA-B80E, non-volatile content 80% by mass, manufactured by Asahi Kasei Chemicals Corporation) were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. To this solution, 80.8 parts of the surface-treated zinc oxide particles A and 0.81 part of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was dispersed for 3 hours in an atmosphere at 23 ± 3 °C using a sand mill apparatus with glass beads having a diameter of 0.8 mm. After the dispersion treatment, 0.01 part of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (former: Toray Dow Corning Silicone Co., Ltd.)) and 5.6 parts of crosslinked polymethyl methacrylate (PMMA) particles (trade name: Tech Polymer SSX-103, manufactured by Sekisui Chemical Products Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer. The obtained coating solution for the 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 an undercoat layer with a film thickness of 18 μm.

[0037] (Charge generation layer) 4 parts of crystalline hydroxygallium phthalocyanine crystals (charge generating substance) having strong peaks at 7.4° and 28.1° of the Bragg angle 2θ ± 0.2° in CuKα characteristic X-ray diffraction, and 0.04 part of the compound represented by the following formula (E) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. Then, dispersion treatment was carried out for 1 hour in an atmosphere of 23 ± 3°C using a sand mill with glass beads having a diameter of 1 mm. After the dispersion treatment, 100 parts of ethyl acetate was added to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was dip-coated on the undercoat layer, and the obtained coating film was dried at 90°C for 10 minutes to form a charge generation layer with a film thickness of 0.15 μm.

Chemical formula

[0038] (Charge transport layer) 60 parts of the compound represented by the following formula (F), 30 parts of the compound represented by the following formula (G), 10 parts of the compound represented by the following formula (H), 100 parts of bisphenol Z type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation), and 0.2 part of polycarbonate having a structural unit represented by the following formula (I) (viscosity average molecular weight Mv: 20,000) were dissolved in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane to prepare a coating solution for the charge transport layer. This coating solution for the charge transport layer was dip-coated on the above-mentioned charge generation layer to form a coating film, and the obtained coating film was dried at 115°C for 50 minutes to form a charge transport layer with a film thickness of 18 μm.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0039] (Protective layer) (Preparation of the coating material for the protective layer) Put alumina balls with a diameter of 5 mm into a 70 cc glass pot, and further add 8% by mass of aluminum oxide particles (Sumikoland AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.), 0.2% by mass of a polycarboxylic acid compound (low molecular weight unsaturated polycarboxylic acid polymer solution, BYK-P104, non-volatile content 50%, manufactured by BYK Chemie), and 8% by mass of cyclopentanone, and disperse (150 rpm) for 24 hours using a ball mill. Then, 12% by mass of tetrahydrofuran was added and stirred to obtain a mill base.) 3% by mass of the obtained mill base, 4% by mass of TMPTA: trimethylolpropane triacrylate (a trifunctional radical polymerizable compound, manufactured by Tokyo Chemical Industry Co., Ltd.) as a polymerizable compound having no charge transport property, 4% by mass of a radical polymerizable material having a monofunctional charge transport compound (the following compound), 0.5% by mass of a photoinitiator (1-hydroxy-cyclohexyl-phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals), 0.01% by mass of a leveling agent (a polydimethylsiloxane solution having a polyester-modified acrylic group, BYK-UV3510, manufactured by BYK Chemie), and 50% by mass of tetrahydrofuran were mixed to prepare a coating material for the protective layer.) [Chemical formula] This coating material for the protective layer was spray-coated on the charge transport layer, and light irradiation was performed under the conditions of an irradiation intensity of 500 mW / cm 2 2 and an irradiation time of 20 seconds, and further dried at 130 °C for 30 minutes to form a protective layer with a thickness of 5.0 μm, thereby producing the photosensitive drum 1.)

[0040] [Photosensitive drum example 2] In Example 1 of the photosensitive drum, a photosensitive drum 2 was obtained in the same manner except that the coating liquid for the protective layer was changed as follows.

[0041] (Coating liquid 2 for protective layer) 3.75 parts of a graft copolymer having a repeating structural unit represented by the following formula (A1) and a repeating structural unit represented by the following formula (A2) was dissolved in a mixed solvent composed of 300 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) and 300 parts of 1-propanol to prepare a dispersant solution. 40 parts of polytetrafluoroethylene resin particles (average primary particle size: 210 nm, average roundness: 0.85) were added to the obtained dispersant solution. Then, it was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics Corporation, USA) to obtain a 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 to the obtained polytetrafluoroethylene resin particle dispersion. Then, filtration was performed using a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating liquid for protective layer). [Chemical formula] [Chemical formula] [Chemical formula] This coating solution for the protective layer was dip-coated onto the charge transport layer to form a coating film, and the obtained 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 the conditions of an accelerating voltage of 70 kV and an absorption dose of 15 kGy in a nitrogen atmosphere. Then, a heat treatment was performed for 15 seconds under the condition that the temperature of the coating film reached 135 °C in a nitrogen atmosphere. The oxygen concentration from the electron beam irradiation to the heat treatment for 15 seconds was 15 ppm. Next, in the air, it was naturally cooled until the temperature of the coating film reached 25 °C, and then a heat treatment was performed for 1 hour under the condition that the coating film reached 105 °C to form a surface layer (protective layer) with a film thickness of 5 μm.

[0042] [Photosensitive drum 3] In the photosensitive drum 1, the aluminum oxide particles in the mill base (Sumikolandum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) were replaced with a silica filler (KMPX-100, average primary particle size: 0.1 μm, manufactured by Shin-Etsu Chemical Co., Ltd.). The photosensitive drum 3 was produced in the same manner as in Example 1 of the photosensitive drum.

[0043] [Photosensitive drum 4] In the photosensitive drum 1, the photosensitive drum 4 was obtained in the same manner except that the protective layer paint was prepared without adding aluminum oxide particles.

[0044] [Photosensitive drum 5] In the photosensitive drum 2, the photosensitive drum 5 was obtained in the same manner except that the protective layer paint was prepared without adding polytetrafluoroethylene resin particles and the graft copolymer represented by the above formulas (A-1) and (A-2).

[0045] [Protective agent] 100 parts by mass of zinc stearate (manufactured by Wako Pure Chemical Industries, Ltd.), which is a fatty acid metal salt, was heated and melted, injection-molded into a mold, cooled and solidified. Then, the solid was removed from the mold, cut into a size of 10 mm × 21 mm × 300 mm, and attached to a metal support with double-sided tape to produce a protective agent. The produced protective agent was attached to the position of the protective agent supply means 108a in the image forming apparatus shown in FIG. 1B. Examples 1 to 13 and Comparative Examples 1 to 2 combined the materials of the photosensitive drums 1 to 5, the protective agent, the lubricant, and the material of the drum rubbing member as shown in Table 1.

[0046] The fatty acid metal salts used as the protective agent and the lubricant were as follows. - Fatty acid metal salt - · Zinc stearate: manufactured by Tokyo Chemical Industry Co., Ltd. · Magnesium stearate: manufactured by Tokyo Chemical Industry Co., Ltd. · Calcium stearate: manufactured by Nitto Kasei Kogyo Co., Ltd. · Zinc laurate: manufactured by Tokyo Chemical Industry Co., Ltd. · Sodium myristate: manufactured by Nitto Kasei Kogyo Co., Ltd. · Magnesium oleate: manufactured by Nitto Kasei Kogyo Co., Ltd. In addition, the following inorganic lubricants were used as the lubricant. - Inorganic lubricant - · Boron nitride: manufactured by Shogoban Co., PCTP2, tap density: 0.2 g / cm 3

[0047] The refractive index shown in Table 1 was measured using a spectroscopic ellipsometer (such as SE - 1000) on a sample prepared by applying a protective agent or a lubricant onto a single - layer film of the protective layer so that the coating thickness became 0.5 μm.

[0048]

Table 1

[0049] [Evaluation] The materials of the drum rubbing parts of the photosensitive drums and the lens array cleaning members obtained in Examples 1 to 13 and Comparative Examples 1 to 2 were evaluated as follows.

[0050] (Evaluation machine 1) In the evaluation, evaluation was carried out using Evaluation Machine 1, which was a multi - function machine imageRUNNER ADVANCE C5870F (registered trademark) manufactured by Canon Inc. and modified as follows. Evaluation was carried out using a modified machine provided with the exposure apparatus cited in the above example in the portion where the exposed portion was removed. Furthermore, a bar in which a protective agent was solidified in the longitudinal direction of the photosensitive drum so that the protective agent was supplied to the surface of the photosensitive drum as the photosensitive drum rotated while contacting the photosensitive drum was fixed at a position upstream in the rotation direction from the drum cleaning means. The above evaluation apparatus was installed in a normal temperature and humidity environment of 23°C and 50% RH, and the produced photosensitive drum was attached to the process cartridge for cyan, and the evaluation was carried out by attaching it to the station of the cyan process cartridge.

[0051] (Evaluation machine 2) In the evaluation, evaluation was carried out using Evaluation Machine 2 obtained by performing the following modifications on the multifunction machine imageRUNNER ADVANCE C5870F (registered trademark) manufactured by Canon Inc. An exposure apparatus cited in the above example was provided in the portion where the exposed portion was removed, and a mechanism for supplying a lubricant to the drum rubbing portion of the lens array cleaning member was provided in the middle of the path where the lens array cleaning member was inserted. Furthermore, a bar in which a protective agent was solidified in the longitudinal direction of the photosensitive drum so that the protective agent was supplied to the surface of the photosensitive drum as the photosensitive drum rotated while contacting the photosensitive drum was fixed at a position upstream in the rotation direction from the drum cleaning means. The above evaluation apparatus was installed in a normal temperature and humidity environment of 23°C and 50% RH, and the produced photosensitive drum was attached to the process cartridge for cyan, and the evaluation was carried out by attaching it to the station of the cyan process cartridge.

[0052] (Exposure unevenness image evaluation) The exposure unevenness image evaluation was carried out using the above Evaluation Apparatus 1 and Evaluation Apparatus 2. In the case of Evaluation Machine 1, place the photosensitive drum in the cyan station of the above evaluation device, and apply a lubricant uniformly in advance to the drum rubbing part of the lens array cleaning member. In the case of Evaluation Machine 2, install a solid bar in which the lubricant is solidified in the middle of the insertion path of the lens array cleaning member. The types of lubricants to be applied or installed are shown in Table 1. After performing the printing operation for 50 sheets, while rubbing the photosensitive drum with the lens array cleaning member, after performing the wiping operation of the lens array 10 times, in the density measurement using X-Rite (manufactured by X-Rite), a halftone image is output so that the cyan value becomes 1.35, and the level of shading unevenness of the image is evaluated. A: No shading unevenness B: Slight shading unevenness C: Shading unevenness occurs D: Shading unevenness

[0053] (Lubricant evaluation) The evaluation of the lubricant on the photosensitive drum was carried out using the above Evaluation Device 1 and Evaluation Device 2. In the case of Evaluation Machine 1, place the photosensitive drum in the cyan station of the above evaluation device, and apply a lubricant uniformly in advance to the drum rubbing part of the lens array cleaning member. In the case of Evaluation Machine 2, install a solid bar in which the lubricant is solidified in the middle of the insertion path of the lens array cleaning member. The types of lubricants to be applied or installed are shown in Table 1. After performing the printing operation for several sheets, while rubbing the photosensitive drum with the lens array cleaning member, perform the wiping operation of the lens array 10 times, remove the photosensitive drum from the multifunction machine, and the lubricant loading amounts at the part where the drum rubbing part is in contact (referred to as the contact part) and the part not in contact (referred to as the non-contact part) were detected for the divalent metal elements contained in the protective agent and the lubricant by a Quantum 2000 type scanning X-ray photoelectron spectrometer (XPS) manufactured by PHI. As an example, the results of measurement by XPS for a sample in which the same zinc stearate is applied to the surface of a photosensitive drum as a protective agent or a lubricant will be described. The measurement was performed within a circle with an X-ray source of AlKα and an analysis region diameter of 100 [μm] for the amount of elements existing at a depth of 20 to 50 [Å] from the outermost surface of the photosensitive drum. The measurement was made by comparing the contact part and the non-contact part of the lens array cleaning member. Here, the surface region of the photosensitive drum measured by XPS is composed of at least only carbon element (C), oxygen element (O), silica element (Si), zinc element (Zn) and hydrogen element (H). Also, the zinc element (Zn) is configured not to exist in constituent substances other than zinc stearate. Note that the hydrogen element (H) is not detected by measurement by XPS. Since the detection values obtained by measurement by XPS vary in measurement sensitivity depending on the measured element, it is better to compare them after converting to per 1 mole of molecules. When zinc stearate with a molecular weight of 41 is used as the protective agent and the lubricant, if the detection amount Z0 of zinc element (Zn) per 1 mol on the photosensitive drum when the protective agent Xg is applied to the photosensitive drum is obtained, then Z0 = detection value / (X ÷ 41). The detection amount of zinc element (Zn) at the non-contact part where the wiping operation by the lens array cleaning member is not performed is Z A and the detection amount of zinc element (Zn) at the contact part where the wiping operation by the lens array cleaning member is performed is Z B When this is done, the smaller the numerical value of the following formula (1), the smaller the difference in the detection amount of the divalent metal element between the contact part and the non-contact part of the lens array cleaning member, that is, the smaller the difference in the abundance of the protective agent and the lubricant on the photosensitive drum, and it can be said that uneven exposure is less likely to occur. Formula (1) = Zn A / Zn0 - Zn B / Zn0 Even when the protective agent and the lubricant contain different divalent metal elements, the detection amounts of the divalent metal elements at the contact part and the non-contact part of the lens array cleaning member are added to calculate the difference in the amount of metal elements on the surface of the photosensitive drum. For example, when simultaneously detecting the divalent metal elements contained in the lubricant shown in this embodiment, the difference in the amount of metal elements can be calculated by the following formula (2). Zinc is denoted as Zn, magnesium as Mg, calcium as Ca, and sodium as Na. Formula (2) = (Zn A / Zn0 + Mg A / Mg0 + Ca A / Ca0 + Na A / Na0 ···) - (Zn B / Zn0 + Mg B / Mg0 + Ca B / Ca0 + Na B / Na0 ···) Table 2 shows the results of evaluating the exposure unevenness based on the numerical difference between the contact part and the non-contact part calculated by Formula (2). A: 0 to 5 or less, no exposure unevenness B: Greater than 5 and 15 or less, there is slight exposure unevenness but the influence is small C: Greater than 15 and 20 or less, exposure unevenness is confirmed D: Greater than 20, significant exposure unevenness

[0054]

Table 2

[0055] The embodiments of the present invention include the following configurations. (Configuration 1) A photosensitive drum rotatable about a rotation axis, A photosensitive drum protector supply means having a protector and applying or adhering the protector to the surface of the photosensitive drum when the photosensitive drum rotates, A plurality of light-emitting elements for emitting exposure light 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, in which a plurality of lenses for condensing 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 is inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and while rubbing the surface of the photosensitive drum and the light emitting surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array, the light emitting surface of the lens array is cleaned. An image forming apparatus having: The cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum. The drum rubbing portion contains a lubricant. The difference between the refractive index of the protective agent and the refractive index of the lubricant is 0.15 or less. An image forming apparatus characterized by the above. (Configuration 2) A photosensitive drum rotatable about a rotation axis, A photosensitive drum protective agent supply means having a protective agent and applying or adhering the protective agent to the surface of the photosensitive drum when the photosensitive drum rotates, A plurality of light emitting elements for emitting exposure light irradiated onto the surface of the photosensitive drum, A lens array having a light incident surface facing the light emitting elements and a light emitting surface facing the photosensitive drum, in which a plurality of lenses for condensing 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 is inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and while rubbing the surface of the photosensitive drum and the light emitting surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array, the light emitting surface of the lens array is cleaned. An image forming apparatus having: The cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum. The image forming apparatus has a cleaning member lubricant supply means for applying or adhering a lubricant to the drum rubbing portion before the cleaning member rubs against the surface of the photosensitive drum and the light emitting surface of the lens array. The difference between the refractive index of the protective agent and the refractive index of the lubricant is 0.15 or less. An image forming apparatus characterized by the above. (Configuration 3) The image forming apparatus according to Configuration 1 or 2, wherein the refractive index of the protective agent is 1.4 or more and 1.7 or less. (Configuration 4) The image forming apparatus according to any one of Configurations 1 to 3, wherein the protective agent contains a fatty acid metal salt. (Configuration 5) The image forming apparatus according to any one of Configurations 1 to 4, wherein the protective agent contains at least one selected from the group consisting of a stearic acid metal salt and a lauric acid metal salt. (Configuration 6) The image forming apparatus according to any one of Configurations 1 to 3, wherein the protective agent contains at least one selected from the group consisting of zinc stearate and zinc laurate. (Configuration 7) The image forming apparatus according to any one of Configurations 1 to 6, wherein the refractive index of the lubricant is 1.4 or more and 1.7 or less. (Configuration 8) The image forming apparatus according to any one of Configurations 1 to 7, wherein the lubricant contains a fatty acid metal salt. (Configuration 9) The image forming apparatus according to any one of Configurations 1 to 8, wherein the lubricant contains at least one selected from the group consisting of a stearic acid metal salt and a lauric acid metal salt. (Configuration 10) The image forming apparatus according to any one of Configurations 1 to 9, wherein the lubricant contains at least one selected from the group consisting of zinc stearate and zinc laurate. (Configuration 11) The image forming apparatus according to any one of Configurations 1 to 10, wherein the difference between the refractive index of the protective agent and the refractive index of the surface layer of the photosensitive drum is 0.20 or less.

Explanation of Signs

[0056] 10 Rotation axis 101 Paper feeding unit 102 Image forming unit 103 Photosensitive drum 104 Charger T Primary transfer unit T2 Secondary transfer unit P recording paper 105 LED exposure head 106 Developing device 107 Intermediate transfer belt 108 Drum cleaning unit 108a Protective agent supply means 108b Drum cleaning means 109 Secondary transfer roller 110 Fuser 111 Paper discharge unit 202 Light-emitting element substrate 203 Light-emitting element 205 Housing 206 Lens array 300 Lens array cleaning member 301 Cleaning unit 302 Gripping part 303 Body part 401 Lens array rubbing part 402 Drum rubbing part 501 Lubricant supply means 502 Insertion port 601 Support 602 Underlayer 603 Charge generation layer 604 Charge transport layer 605 Protective layer

Claims

1. A photosensitive drum rotatable about a rotation axis, a photosensitive drum protector supply means having a protector and applying or adhering the protector to the surface of the photosensitive drum during rotation of the photosensitive drum, a plurality of light emitting elements for emitting exposure light irradiated onto the surface of the photosensitive drum, a lens array having a light incident surface facing the light emitting elements and a light emitting surface facing the photosensitive drum, wherein a plurality of lenses for condensing 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 inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and cleaning the light emitting surface of the lens array while rubbing the surface of the photosensitive drum and the light emitting 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 comprising: the cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum, the drum rubbing portion has a lubricant, a difference between the refractive index of the protector and the refractive index of the lubricant is 0.15 or less, An image forming apparatus characterized by the above.

2. A photosensitive drum rotatable about a rotation axis, a photosensitive drum protector supply means having a protector and applying or adhering the protector to the surface of the photosensitive drum during rotation of the photosensitive drum, a plurality of light emitting elements for emitting exposure light irradiated onto the surface of the photosensitive drum, a lens array having a light incident surface facing the light emitting elements and a light emitting surface facing the photosensitive drum, wherein a plurality of lenses for condensing 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 inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and cleaning the light emitting surface of the lens array while rubbing the surface of the photosensitive drum and the light emitting 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 comprising: the cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum, the image forming apparatus has a cleaning member lubricant supply means for applying or adhering a lubricant to the drum rubbing portion before the cleaning member rubs against the surface of the photosensitive drum and the light emitting surface of the lens array, a difference between the refractive index of the protector and the refractive index of the lubricant is 0.15 or less, An image forming apparatus characterized by the above.

3. The image forming apparatus according to claim 1 or 2, wherein the refractive index of the protective agent is 1.4 or more and 1.7 or less.

4. The image forming apparatus according to claim 1 or 2, wherein the protective agent contains a fatty acid metal salt.

5. The image forming apparatus according to claim 1 or 2, wherein the protective agent contains at least one selected from the group consisting of a stearic acid metal salt and a lauric acid metal salt.

6. The image forming apparatus according to claim 1 or 2, wherein the protective agent contains at least one selected from the group consisting of zinc stearate and zinc laurate.

7. The image forming apparatus according to claim 1 or 2, wherein the refractive index of the lubricant is 1.4 or more and 1.7 or less.

8. The image forming apparatus according to claim 1 or 2, wherein the lubricant contains a fatty acid metal salt.

9. The image forming apparatus according to claim 1 or 2, wherein the lubricant contains at least one selected from the group consisting of a stearic acid metal salt and a lauric acid metal salt.

10. The image forming apparatus according to claim 1 or 2, wherein the lubricant contains at least one selected from the group consisting of zinc stearate and zinc laurate.

11. The image forming apparatus according to claim 1 or 2, wherein the difference between the refractive index of the protective agent and the refractive index of the surface layer of the photosensitive drum is 0.20 or less.

Images