JP2694745B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a photoconductor made of an organic photoconductor, and further, an elastic conductor is brought into contact with the surface of the photoconductor to directly charge the surface of the photoconductor by applying a voltage. The present invention relates to an electrophotographic apparatus having a charging mechanism. [Prior Art] The electrophotographic apparatus is a CdS-resin dispersion system, a ZnO-resin dispersion system,
Copies can be made by performing the basic steps of charging, exposure, development and transfer fixing cleaning on each photoconductor of Se, Se-Te vapor deposition system, amorphous silicon system and cheap and easy to manufacture organic photoconductor (OPC) system. It has gained. In the charging process at this time, a corona generated by applying a high voltage (DC 5 to 8 kV) to most metal wires has been used for charging. With this method, however, a large amount of corona products such as ozone NO _X are generated when corona is generated, and the corona products deteriorate the surface of the photoconductor to promote image blurring and deterioration, and wire stains immediately cause image quality deterioration. Therefore, there are problems such as white spots and black streaks in the image.
On the other hand, in terms of electric power, only 5 to 30% of the electric current is directed to the photoconductor, and most of the electric current flows to the shield plate, which is inefficient as a charging means. In order to make up for such drawbacks, a method of directly charging directly has been studied and many proposals have been made (JP-A-57-178267,5).
6-104351, 58-40566, 58-139156, 58-150975 etc.). Further, as described above, inorganic photoconductive materials such as amorphous silicon, selenium, cadmium sulfide, and zinc oxide are known as photoconductive materials used in electrophotographic photoreceptors. These photoconductive materials have a number of advantages, such as being able to be charged to an appropriate potential in the dark, having a low dissipation of charges in the dark, or being capable of rapidly dissipating charges by light irradiation. However, it has various drawbacks. For example, selenium-based photoreceptors easily crystallize due to factors such as temperature, humidity, dust, and pressure.In particular, when the ambient temperature exceeds 40 ° C, crystallization becomes noticeable, resulting in reduced chargeability and white spots on images. There is a drawback that occurs. Further, the selenium-based photoconductor and the cadmium sulfide-based photoconductor have the drawback that stable sensitivity and durability cannot be obtained when they are used for a long time under high humidity. Further, the zinc oxide type photoconductor requires a sensitizing effect by a sensitizing dye typified by rose bengal. However, such a sensitizing dye has a long-term effect because the charge deterioration due to corona charging causes photobleaching by exposure light. However, it has a drawback that a stable image cannot be provided over the entire range. On the other hand, various organic photoconductive polymers such as polyvinylcarbazole have been proposed, but these polymers are superior in film forming property, light weight, and high productivity to the inorganic photoconductive materials described above. The reason why it has been difficult to put it into practical use until now is that it is inferior to inorganic photoconductive materials in terms of sensitivity, durability and stability due to environmental changes. Moreover, a suitable sensitizer capable of achieving sufficiently high sensitivity has not been found yet. For these reasons, in recent years, many organic photoconductive substances having a low molecular weight have been developed in place of polymer-based organic photoconductive substances. The advantage of low molecular weight organic photoconductive materials is that the range of compounds that can be selected is widened, and therefore, one with good sensitivity and charge retention can be selected. A laminated structure photoconductor (called an OPC photoconductor) in which the functions are separated into layers has been proposed, and it has become possible to manufacture a photoconductor with higher sensitivity. However, this OPC photosensitive member has a drawback in that deterioration and deterioration due to the corona product described above are more likely to occur than other photosensitive members. That is, currently used OPC photoconductors have lower chemical stability than other amorphous silicon and Se photoconductors, and when exposed to the corona products, they tend to undergo a chemical reaction (mainly an oxidation reaction) and tend to deteriorate. It is in. Therefore, when it is repeatedly used under corona charging, image blurring due to the above-described deterioration and low copy density due to a decrease in sensitivity occur, which has been a cause of shortening the printing durability life of the OPC photoreceptor. Therefore, when an OPC photoconductor is used in an electrophotographic apparatus, the charging efficiency is high, and the charging by direct electrification that produces an extremely small amount of corona products suppresses the occurrence of image defects (image blur etc.) It is very useful from the standpoint of extending the print life of. However, on the other hand, the direct charging method as described above has not been marketed at all, despite many proposals. This is due to the uniformity of charging and the occurrence of discharge dielectric breakdown of the photoreceptor due to direct voltage application. Regarding the problem of non-uniform charging, it is improved by uniformly contacting the photosensitive material with an elastic conductive material with a certain load with a nip width of a certain value or more, especially in combination with an OPC photosensitive material. In this case, since the OPC photosensitive member itself has elasticity, the charging uniformity tends to be obtained without increasing the load so much.
However, if too much load is applied at this time, the surface hardness of the OPC photoconductor is low, which may cause damage to the photoconductor. Regarding the problem of dielectric breakdown in direct charging, the surface hardness of OPC is particularly low compared to other photoconductors, so scratches are likely to occur on the photoconductor, and the current leakage during direct charging due to these scratches is directly charged. It was a major cause that prevented the introduction of the law. [Problems to be Solved by the Invention] An object of the present invention is to solve the above problems and to provide an inexpensive electrophotographic apparatus using a non-polluting OPC photoconductor, image deletion, an image with a low copy density, etc. OPC with no defects
An object of the present invention is to provide an electrophotographic apparatus having an extremely long printing life of a photoreceptor. [Means for Solving the Problems] That is, according to the present invention, a DC voltage and an AC voltage are applied to an elastic conductor brought into contact with a photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive substrate. Thus, in the electrophotographic apparatus for charging the surface of the photoconductor, the contact width between the elastic conductor and the photoconductor is 0.5 mm or more, and the load per unit area of the contact surface is 0.5 gr / mm ² or more. The electrophotographic apparatus is characterized in that the surface hardness of the body is 15 gr or more, and the number of grams of load per unit area of the contact surface is not more than twice the number of grams of surface hardness of the photoconductor. Hereinafter, the present invention will be described in more detail. As described above, in the electrophotographic apparatus, various proposals have been made so far regarding a method of bringing a conductive material into contact with the surface of a photoreceptor and applying a voltage to the surface to charge the surface of the photoreceptor (hereinafter, abbreviated as direct charging). There is. The method of direct charging in the present invention is not limited to a specific method except that the elastic conductive material is brought into contact with the photoconductor with a constant load. The shape of the elastic conductive material may be any of a roller, a brush, a blade, and a belt, and can be selected according to the specifications and form of the electrophotographic apparatus. As the material of the elastic conductive material, conductive polymer material such as polyacetylene, polypyrrole, polytheophene, rubber, artificial fiber or polycarbonate treated by dispersing carbon, metal, etc., or insulating material such as polyvinyl, polyethylene It is possible to use a material whose surface is coated with a metal or another conductive material. The resistance of the elastic conductive material brought into contact with these photoconductors is preferably 10 ⁰ to 10 ¹² Ωcm, optimally 10 ² from the viewpoint of good charging and prevention of dielectric breakdown.
It is in the range of up to 10 ¹⁰ Ωcm. The installation of the elastic conductive material to be brought into contact with the photosensitive member in the present invention is not limited to a specific method, and the elastic conductive material may be a fixed method or a moving method such as rotation in the same direction as the photosensitive member or in the opposite direction. It can also be used. Further, the elastic conductive material can also function as a cleaning device for cleaning the toner on the photoconductor. The voltage applied to the elastic conductive material in the direct charging according to the present invention is DC + AC. Further, regarding the application method, depending on the specifications of each electrophotographic apparatus, in addition to a method of instantly applying a desired voltage, a method of gradually increasing the applied voltage for the purpose of protecting the photoconductor, Further, a method of applying a voltage in the order of DC → AC or AC → DC can be adopted. The nip width between the photoconductors of the elastic conductive material is substantially determined by the relationship between the elasticity of the elastic conductive material and the total load. In the electrophotographic apparatus of the present invention, the nip width needs to be 0.5 mm or more. The method of applying a load between the elastic conductive material and the photoconductor in the present invention is not particularly limited. The load may be the weight of the elastic conductive material, or an external load such as a metal spring or rubber. As a method for calculating the load per unit area, the contact width (nip width) × contact length between the elastic conductive material and the photoconductor is defined as the area S, and the total load (gr) is divided by this S. Here, the load per unit area is preferably 0.5 to 30 gr / mm
² Optimally, the range is 1 to 20 gr / mm ² . In the electrophotographic photoreceptor of the present invention, the photosensitive layer is composed of an organic photoconductor, but as the organic photoconductor used for the photosensitive layer, one using an organic photoconductive polymer such as polyvinylcarbazole or a low photoconductor is used. For example, an organic photoconductive substance having a molecular weight is used as an insulating polymer as a binder.
Among these, the function-separated type photoreceptor having a laminated structure in which the photosensitive layer has a charge transport layer and a charge generation layer as components, in particular, a structure in which the charge generation layer and then the charge transport layer are laminated in this order from the conductive substrate side Photoreceptors are preferred in the present invention. In the case of producing the electrophotographic photosensitive member of the present invention, the conductive substrate may be a metal such as aluminum or stainless steel, paper,
A cylindrical cylinder or film such as plastic is used. An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided on these substrates. The undercoat layer improves the adhesiveness of the photosensitive layer, improves coating properties, protects the substrate, covers defects on the substrate, improves charge injection from the substrate,
It is formed to protect the photosensitive layer against electrical breakdown. Examples of the material of the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide,
Ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, copolymerized nylon, glue, gelatin, etc. are known. These are dissolved in a suitable solvent and applied onto a substrate. Its film thickness is about 0.2 to 2 μm. In the function-separated type photoreceptor, as the charge generating substance,
Pyrylium, thiopyrylium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments, pyratron pigments, trisazo pigments, bisazo pigments,
Azo pigments, indigo pigments, quinacdrine pigments, asymmetric quinocyanines, quinocyanines and the like can be used. Further, as the charge transporting substance, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-
Ethylcarbazole, N, N-diphenylhydrazino-3
-Methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-
Phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone- 2-hydrazones and other hydrazones, 2,5
-Bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p-ditylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl (2 )]-3- (p-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-
Diethylaminostyryl) -5- (p-cyethylaminophenyl) pyrazoline, 1- [6-methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazolin, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Lepidyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-methyl-5 -(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3-
(Α-methyl-p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazolin, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazolin,
Pyrazolines such as 1-phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline and spiropyrazoline;
(P-diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2
Oxazole compounds such as -chlorophenyl) oxazole, thiazole compounds such as 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole,
Triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) -phenylmethane, 1,1-
Polyarylalkanes such as bis (4-N, N-diethylamino-2-methylphenyl) heptane and 1,1,2,2-tetrakis- (4-N, N-dimethylamino-2-methylphenyl) ethane Can be used. For the charge generation layer, the charge generation substance is well dispersed together with a binder resin in an amount of 0.5 to 4 times and a solvent by a method such as a homogenizer, ultrasonic wave, ball mill, vibrating ball mill, sand mill, attritor or roll mill, and applied. -Dried and formed. Its thickness is about 0.1 to 1 μm. The charge transport layer is generally formed by dissolving the above charge transport substance and the binder resin in a solvent and coating the charge transport layer on the charge generation layer. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. As the solvent, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate,
Aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride are used. When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method, or the like can be used, and drying is performed at 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C.
It can be carried out at a temperature in the range of ° C for 5 minutes to 5 hours, preferably 10 minutes to 2 hours under blast drying or static drying. The thickness of the generated charge transport layer is about 5 to 20 μm. Examples of the binder resin used to form the charge transport layer include acrylic resin, styrene resin, polyester,
Polycarbonates, polyarylate, polysulfone,
A resin selected from polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, unsaturated resin and the like is preferable. Particularly preferred resins include polymethylmethacrylate, polystyrene, styrene-acrylonitrile copolymers, polycarbonates or diallylphthalate resins, among which polymethylmethacrylate, polystyrene, styrene-acrylonitrile copolymers or diallylphthalate resins are preferred. is there. Further, the charge transport layer of the present invention may contain various additives. Examples of such additives include diphenyl, diphenyl chloride, o-terphenyl, p-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, and dilauryl thiopropionate. , 3,5-dinitrosalicylic acid, various fluorocarbons and the like. The surface hardness of the photosensitive layer in the electrophotographic photosensitive member of the present invention is specifically measured as follows. For example, a photoreceptor is fixed on the sample stand of HEIDON14 type surface texture measuring instrument (manufactured by Shinto Kagaku), and a diamond or sapphire needle (conical with a cone angle of 90 °, with a tip of 0.01 mm in diameter) on the surface of the photosensitive layer. Vertical load is applied to move the sample table at a speed of 50 mm / min.
Scratch the surface of the photosensitive layer. The width of this scratch is measured using, for example, a microscope attached to a micro hardness meter MVK-F (manufactured by Akashi Seisakusho). The above operation, vertical load is 10g, 15g, 20g, 25
Repeat every 5g with g, 30g, 35g, 40g ...
From the linear regression relationship between the scratch width and the load, the load that causes a scratch of 50 μm is calculated and used as the hardness of the photoreceptor. Here, when the photoconductor is a drum, the photoconductor is set on the sample so as to be scratched in the axial direction of the drum. According to the above definition, the surface hardness of the photosensitive layer in the electrophotographic photosensitive member of the present invention needs to be a vertical load of 15 g or more. [Examples] The present invention will be described below with reference to Examples. First, the following samples 1 to 5 were prepared as the OPC photoconductors used in the examples. Sample 1. An 80φ x 360mm aluminum cylinder was used as the base. In addition to this, polyamide resin (trade name: Amilan CM800
0, manufactured by Toray Co., Ltd.)
An undercoat layer having a thickness of 1 μm was provided. Next, 10 parts by weight of a bisazo pigment having the following structural formula (weight part, the same applies hereinafter), 1 part of polyvinyl butyral resin (trade name; S-REC BXL, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone
The mixture was dispersed for 20 hours by a sand mill using φ glass beads. Methyl ethyl ketone 70-120 (appropriate) in this dispersion
Parts were added and coated on the undercoat layer. The thickness was 0.12 μm. next, 7 parts of a hydrazone compound represented by the structural formula and 10 parts of a polystyrene resin (trade name: Dialex HF-55; manufactured by Mitsubishi Monsanto Kasei) were dissolved in 50 parts of monochlorobenzene.
This solution was applied on the charge generation layer. The film thickness after drying
It was 17 μm. When the hardness of the surface of the photoreceptor thus prepared was measured by the above-mentioned measuring method, a value of 13 g was obtained. Sample 2. Styrene instead of the polystyrene resin in Sample 1.
Acrylonitrile copolymer (trade name: Sanrex SAN
-C: manufactured by Mitsubishi Monsanto Kasei Co., Ltd., and a photoconductor was prepared in the same manner as in Sample 1. The surface hardness of this photoconductor was 17 g. Sample 3. Instead of polystyrene resin of sample 1, styrene-
Methyl methacrylate copolymer (Brand name Estrene MS-
300: manufactured by Nippon Steel Chemical Co., Ltd.)
A photoreceptor was prepared in the same manner as described above. The surface hardness of this photoconductor was 21 g. Sample 4. Use the bisazo pigment of the following structural formula instead of the bisazo pigment of Sample 1. A photoconductor was prepared in the same manner as in Sample 1, except that a polycarbonate resin having a weight average molecular weight of 5000 was used instead of the polystyrene resin. The surface hardness of this photoreceptor was 8 gr. Sample 5. Weight average molecular weight of polycarbonate resin of sample 4
A photoconductor was prepared in the same manner as in Sample 1 except that 22,000 was used. The surface hardness of this photoconductor is 22g
Met. Next, the electrophotographic apparatus used in this example is shown. FIG. 1 is a schematic view of the electrophotographic apparatus used in this embodiment. In FIG. 1, 1 is an OPC photosensitive member, 2 is an elastic conductive material for direct charging, 3 is image exposure, and 4 is development. 5 is a transfer paper feed roller and a feed guide, 6 is a transfer charger, 7 is a separation charger, 8 is a transport unit for sending the transfer paper to a fixing device (not shown), 9 is a cleaner, and 10 is the front. It is an exposure light source. (Embodiment 1) FIG. 2 is a conceptual diagram of the conductive charging roller unit used in Embodiment 1, in which 2 is an elastic conductive roller for direct charging, and 11 is a main body side guide rail. Support plate, which is installed as a support for the conductive roller, 12
Is a power supply brush for supplying a voltage to the core of the conductive roller, 13 is a pressure spring for pressing the roller 2 to the photosensitive member 1 via a fulcrum 15, and 14 is a power receiving connector from the main body. Next, the charging unit shown in FIG. 2 was mounted on the electrophotographic apparatus shown in FIG. 1, and 10,000 sheets were printed using the photoreceptors of Samples 1 to 5. The electrophotographic apparatus shown in FIG. 1 is based on Canon NP3525 as a basic form, 3 image exposure, 4 developing device,
5 is a paper feeding system, 6 and 7 chargers, 8 is the pre-exposure of the transport system 10, 1 is the sample 1 to 5 of the photoconductor, 2 is the direct charging system, and 9 is the cleaner. It was modified so that it could be cleaned only with a blade made of silicon rubber. The cleaner blade was set so that the blade pressure was 20 g / cm, the contact angle was 28 °, and the penetration amount was 1.5 mm. The voltage applied to the charging unit for direct charging is DC-70.
0V + AC peak difference is 1500V 1000Hz, and the charging roller in Fig. 2 is 10 by dispersing carbon in urethane rubber.
The resistance was ⁶ Ω · cm. At this time, the nip width between the roller and the photosensitive member was 1.0 mm, and the load per area was 10 gr / mm ² . In addition, printing durability
The test was conducted in an environment of 35 ° C. and 90%, and as evaluation items of these results, attention was paid to image blurring, solid black density low, the number of photoconductor dielectric breakdowns, and uneven density due to uneven charging. Table 1 shows the results. In this way, sample 1 with a surface hardness of 13g and sample 4 with a surface hardness of 8g have a dielectric breakdown due to direct electrification.
None of the other samples mentioned above have occurred. Further, as shown in Comparative Example-1 described later, when a normal corona charger is used, problems such as image blurring and solid black density occur in all of Samples 1 to 5, but direct charging in this Example is not performed. In the system in which the test was performed, no problems such as image blurring and solid black density decrease occurred in any of the samples. (Example-2) The roller No. 2 in FIG. 2 was replaced with a plate-shaped blade having carbon dispersed therein and a resistance of 10 ⁸ Ω · cm,
In the figure, the same electrophotographic apparatus as in Example 1 was used except that the contact was made in the forward direction with respect to the rotation of the photoconductor,
The same printing durability as in Example-1 was performed. At this time, the nip width was 0.6 mm and the load per area was 26 gr. Table 2 shows the results. Here, as in Example-1, when the surface hardness was 15 g or more, the above problems did not occur at all and a good image was obtained. (Embodiment 3) The roller No. 2 in FIG. 2 was replaced with a brush having a conductive artificial fiber in which carbon is dispersed in 66 nylon as shown in the sectional view of FIG. The same printing experiment as in Example 1 was carried out except that the apparatus was installed at the position 2. FIG. 3 shows an iron core of a brush, and 16 is a conductive artificial fiber in which carbon is dispersed in 66 nylon and the resistance is 10 ¹⁰ Ω · cm. At this time, the nip width was 1.2 mm and the unit area was 3.2 gr. Table 3 shows the results. Here, as in Example-1, when the surface hardness was 15 g or more, the above problems did not occur at all and a good image was obtained. (Comparative Example-1) As comparison data, the original NP is shown in the part 2 in FIG.
− Example except that the corona charger of 3525 was used as it was −
Table 4 shows the data when the same printing durability was performed with the photoconductors of Samples 1 to 5 under the same setting as in 1. By using the corona charger as seen here,
In an electrophotographic device that uses a photoconductor containing an organic photoconductor, image blurring and V _L
Up (solid black density) occurs in all samples. (Comparative Example-2) As comparative data, the same experiment as in Example-1 was carried out except that the load per unit area between the conductive roller and the photoconductor in Example-1 was set to 0.3 gr / mm ² . Table 5 shows the results. As described above, when the load per unit area is 0.5 gr / mm ² or less, uneven density occurs due to nonuniformity of direct charging in any of the samples. (Comparative Example-3) As comparative data, in Example-1, the nip width between the conductive roller and the photoconductor is 2.3 mm, and the load per unit area is 40 g.
An experiment was conducted in the same manner as in Example-1 except that r / mm ² was used. The results are shown in Table 6. Thus, when the number of grams of load per unit area exceeds twice the number of grams of surface hardness, dielectric breakdown due to discharge occurs even in a photoreceptor sample having a surface hardness of 15 gr or more. (Effect of the Invention) As described above, in the present invention, in the electrophotographic apparatus using the OPC photosensitive member, the elastic conductive material is brought into contact with the photosensitive member for the charging performed prior to the latent image formation, and the voltage is directly applied thereto. Direct charging is performed, the nip width between the elastic conductive material and the photoconductor is 0.5 mm or more, and the load per unit area is
0.5 gr / mm ² or more, and the surface hardness of the OPC photoreceptor is 15
By using gr or more and by making the number of grams of load per unit area less than or equal to twice the number of grams of surface hardness, (1) prolong the printing life of the photoconductor, (2) image blur, solid black Prevents the occurrence of low density, etc. (3) Prevents the dielectric breakdown that occurs when a voltage is directly applied to the photoconductor, (4)
This makes it possible to provide an electrophotographic apparatus that has the effect of preventing uneven charging due to repeated direct charging and that can repeatedly supply a very high quality copy image overall.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electrophotographic apparatus embodying the present invention, FIG. 2 is a roller charging unit for direct charging, and FIG. 3 is a sectional view of a conductive brush for direct charging. 1 ... Photosensitive member, 2 ... Elastic conductive material, 3 ... Image exposure, 4 ... Developing device, 5 ... Paper feeding system, 6 ... Transfer charging device,
7 ... Separation charger, 8 ... Transfer paper transporting unit, 9 ... Cleaner, 10 ... Pre-exposure light source, 11 ... Support plate, 12 ... Power supply brush, 13 ... Pressure spring, 14 ... Power reception connector,
15 …… fulcrum, 16 …… conductive artificial fiber, 17 …… iron core.

Continuation of front page    (72) Inventor Masami Okunuki               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc. (72) Inventor Hiroyuki Omori               3-30-2 Shimomaruko, Ota-ku, Tokyo               Inside Canon Inc.                (56) Reference JP-A-61-112153 (JP, A)                 JP 64-7070 (JP, A)                 JP-A-64-35464 (JP, A)                 58-88645 (JP, U)                 Actual exploitation Sho 57-199349 (JP, U)

Claims (1)

(57) [Claims] In an electrophotographic apparatus in which a DC voltage and an AC voltage are applied to an elastic conductor brought into contact with a photosensitive member having a photosensitive layer containing an organic photoconductor on a conductive substrate, the elastic conductive member The contact width between the body and the photoreceptor is 0.
With a load of 5 mm or more, the load per unit area of the contact surface is 0.5 gr / mm ²
The electron is characterized in that the surface hardness of the photoconductor is 15 gr or more, and the number of grams of the load per unit area of the contact surface is not more than twice the number of grams of the surface hardness of the photoconductor. Photographic equipment. 2. The electrophotographic apparatus according to claim 1, wherein the photosensitive layer has a charge generation layer and a charge transport layer. 3. The electrophotographic apparatus according to claim (2), wherein the photoreceptor has a charge generation layer and a charge transport layer in this order from the side of the conductive substrate.