JP2003091135A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that sufficiently and uniformly electrifies the surface of a photoreceptor even in the case of a long electrophotographic photoreceptor and obtains sufficiently satisfactory image quality without deteriorating the surface of the photoreceptor even in long term use. SOLUTION: In the image forming apparatus having an electrophotographic photoreceptor, contact electrifying members, an exposure device, a developing device, and a transfer device, the contact electrifying members 2a to 2c are ranged perpendicular to the direction in which the surface of the electrophotographic photoreceptor 1 moves, in such a manner that the ends of the electrifying areas of the adjacent contact electrifying members overlap. Additionally, an AC current that is applied to each contact electrifying member is set to 1.3 mA or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus. More specifically, the surface of one electrophotographic photosensitive member is contacted with a plurality of charging members to charge the surface of the electrophotographic photosensitive member. The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, an image is formed through steps such as charging, exposure, development and transfer. In such charging step, a wire charging method usually called corotron is used. Has been applied. However, there is a problem that ozone or the like is generated when charging with a corotron.

Under such a background, a contact for charging a surface of the electrophotographic photosensitive member by applying a predetermined current while contacting the surface of the electrophotographic photosensitive member with a roll-shaped or brush-shaped charging member (contact charging member). The charging system is being put into practical use.

By the way, for example, the width of the charged surface of the photosensitive member is about 1
When a contact charging member having the same width as the electrophotographic photosensitive member is used in an image forming apparatus having a width as large as m, it is difficult to perform uniform charging due to the influence of the bending of the charging member and poor processability. Met. Moreover, such a long contact charging member cannot be put to practical use in terms of manufacturing cost and the like.

Therefore, various methods have been studied for uniformly charging the surface of the electrophotographic photosensitive member in a wide-width image forming apparatus to which the contact charging method is applied. For example, Japanese Unexamined Patent Publication No. 8-305128 discloses the method. A charging device in which a plurality of contact charging members are distributed in the moving direction of a surface to be charged is disclosed.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
When a plurality of contact charging members are used like the charging device described in Japanese Patent No. 128, they are arranged so that the charging areas of adjacent contact charging members overlap in order to charge the surface of the photoconductor without leakage. There is a need to. However, when an image forming apparatus equipped with such a charging device is used for a long time, toner easily adheres to the overlapping portion of the charging area and the image is easily disturbed. Is likely to occur. Therefore, a wide image forming apparatus to which the contact charging method is applied has not been realized yet, and in reality, a corotron or the like is still used as the charging device.

The present invention has been made in view of the above problems of the prior art. Even when the electrophotographic photosensitive member is long, the surface of the photosensitive member can be sufficiently and uniformly charged, and An object of the present invention is to provide an image forming apparatus capable of obtaining sufficiently good image quality without deterioration of the surface of the photoconductor even when used for a long period of time.

[0008]

In order to solve the above problems, a first image forming apparatus of the present invention comprises an electrophotographic photosensitive member, a charging means for charging the surface of the electrophotographic photosensitive member, and an electrophotographic photosensitive member. An image forming apparatus comprising: an exposing unit that exposes a surface to form an electrostatic latent image; a developing unit that develops the electrostatic latent image; and a transferring unit that transfers the developed image to a transfer medium. The charging means includes a plurality of contact charging members distributed along a direction orthogonal to the moving direction of the electrophotographic photosensitive member surface such that the ends of the charging areas of the adjacent contact charging members overlap. In addition, the alternating current applied to each of the contact charging members is 1.3 mA or less.

In the first image forming apparatus of the present invention, a plurality of contact charging members are moved perpendicularly to the moving direction of the surface of the electrophotographic photosensitive member so that the ends of the charging areas of the adjacent contact charging members overlap. Even if the electrophotographic photosensitive member is long, it is possible to distribute along the direction and set the alternating current applied to each of the contact charging members to 1.3 mA or less.
It is possible to charge the surface of the electrophotographic photosensitive member sufficiently uniformly and without leakage, and it is possible to sufficiently prevent deterioration of the surface of the electrophotographic photosensitive member in the overlapping portion of the charged regions. Therefore, it is possible to obtain excellent image quality for a long period of time without causing the phenomenon that the charging characteristic of the overlapping portion is deteriorated and the fog occurs.

Further, the second image forming apparatus of the present invention forms an electrostatic latent image by exposing the electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, and the surface of the electrophotographic photosensitive member. What is claimed is: 1. An image forming apparatus comprising: an exposing unit, a developing unit for developing an electrostatic latent image, and a transferring unit for transferring the developed image to a transfer medium, wherein an electrophotographic photoreceptor is provided on a conductive substrate. The charge generation layer and the charge transport layer having a film thickness of 24 μm or more are arranged in this order, and the charging means is arranged so that the ends of the charging areas of the adjacent contact charging members overlap.
It is characterized by comprising a plurality of contact charging members distributed along a direction orthogonal to the moving direction of the electrophotographic photosensitive member surface.

In the second image forming apparatus of the present invention, the surface of the electrophotographic photosensitive member in which the charge generation layer and the charge transport layer having a thickness of 24 μm or more are laminated in this order on the conductive substrate is contact charged adjacent to each other. The electrophotographic photosensitive member can be made long by charging by a plurality of contact charging members distributed along the direction orthogonal to the moving direction of the surface of the electrophotographic photosensitive member so that the ends of the charging regions of the members overlap. Even if it exists, the surface of the electrophotographic photosensitive member can be charged sufficiently uniformly and without leakage, and deterioration of the surface of the electrophotographic photosensitive member in the overlapping portion of the charged regions can be sufficiently prevented. Therefore, it is possible to obtain excellent image quality for a long period of time without causing a phenomenon in which toner adheres to the overlapping portion to disturb the image or a phenomenon in which the charging characteristic of the overlapping portion is deteriorated and fogging occurs.

In the second image forming apparatus of the present invention,
The alternating current applied to each of the contact charging members is 1.3.
It may be characterized by being mA or less. This allows
It is possible to more reliably prevent the phenomenon in which the toner is attached to the overlapping portion and the image is disturbed, and the phenomenon in which the charging characteristic of the overlapping portion is deteriorated and fogging occurs, and the image quality is further improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawing,
The same or corresponding parts will be denoted by the same reference symbols and redundant description will be omitted.

FIG. 1 shows a first embodiment of the image forming apparatus of the present invention.
It is a schematic structure figure showing an embodiment. In the apparatus shown in FIG. 1, the electrophotographic photosensitive member 1 is supported by a support 9 and is rotatable about the support 9 in the direction of the arrow at a predetermined rotation speed. Then, along the rotation direction of the electrophotographic photosensitive member 1, the three contact charging members 2a-2
c, the exposure device 3, the developing device 4, the transfer device 5, and the cleaning means 7 are arranged in this order. Further, the apparatus is provided with an image fixing device 6, and the transfer medium P is the transfer device 5.
Then, the image is conveyed to the image fixing device 6.

The electrophotographic photosensitive member 1 has a photosensitive layer formed on a cylindrical conductive substrate, and the photosensitive layer contains a charge generating substance and a charge transporting substance. The electrophotographic photoreceptor 1 used in the first embodiment is a laminated photoreceptor in which a charge generating substance and a charge transporting substance are contained in separate layers (charge generating layer, charge transporting layer) and these are laminated. It may be a single layer type photoconductor containing both the charge generating substance and the charge transporting substance in the same layer, but is preferably a laminated type photoconductor. The charge generating substance and the charge transporting substance are not particularly limited, but for example, the charge generating substance and the charge transporting substance exemplified in the description of the second embodiment described later can be used.

The contact charging members 2a to 2c have a cylindrical shape (roller shape), and are formed by laminating an elastic layer, a resistance layer and a protective layer in this order on the outer peripheral surface of a conductive core material.
As the core material, a material having conductivity such as iron, copper, brass, stainless steel, aluminum, nickel, or a resin molded product in which conductive particles are dispersed can be used.

The material of the elastic layer is EPDM,
Polybutadiene, natural rubber, polyisobutylene, SB
R, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer,
Rubber materials such as norbornene rubber, fluorosilicone rubber, ethylene oxide rubber, carbon black, zinc,
Aluminum, copper, iron, nickel, chromium, metals such as _{titanium, ZnO-Al 2 O 3,} SnO 2 -Sb 2 O 3,
_{In 2 O 3 -SnO 2, ZnO} -TiO 2, MgO-Al 2
_{O 3, FeO-TiO 2,} TiO 2, SnO 2, Sb 2 O 3,
A material in which conductive particles or semiconductive particles such as metal oxides such as In ₂ O ₃ , ZnO and MgO are dispersed is preferably used.

Further, as the material of the resistance layer and the protective layer,
Acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, the above conductive particles or semiconductive particles.
Dispersed in polythiophene resin, polyolefin resin such as PFA, FEP, PET, and styrene-butadiene resin,
Those whose resistance is controlled are preferably used. Furthermore, in the resistance layer and the protective layer, if necessary, an antioxidant such as hindered phenol, hindered amine, clay,
Fillers such as kaolin and lubricants such as silicone oil can be added. As means for forming these layers, blade coating method, Meyer bar coating method, spray coating method, dip coating method,
Bead coating method, air knife coating method,
A curtain coating method or the like can be used.

The resistivity of the resistance layer and the protective layer is preferably 1
0 ³ to 10 ¹⁴ Ωcm, more preferably 10 ⁶ to 10 ¹² Ωc
m, and more preferably 10 ⁷ to 10 ¹² Ωcm. The resistance layer and the protective layer preferably have a thickness of 0.
01-1000 μm, more preferably 0.1-500 μm
m, and more preferably 0.5 to 100 μm.

2A and 2B of the electrophotographic photosensitive member 1 and the contact charging members 2a to 2c in this embodiment.
2A and 2B are a perspective view and a top view showing the positional relationship between the electrophotographic photosensitive member 1 and the contact charging members 2a to 2c in the image forming apparatus shown in FIG. As shown in FIGS. 2A and 2B, in the present embodiment, the contact charging members 2a and 2c are
They are arranged at a predetermined interval along a direction (rotational axis direction of the electrophotographic photosensitive member 1) orthogonal to the moving direction of the surface of the electrophotographic photosensitive member 1 (the arrow direction in the drawing). Further, the contact charging member 2b is for charging the surface of the electrophotographic photosensitive member 1 which has not been charged by the contact charging members 2a and 2c, and both ends of the charging area by the contact charging member 2b are the contact charging member 2a. 2c is arranged so as to overlap the end of the charging area.

When the surface of the electrophotographic photosensitive member 1 is charged by the contact charging members 2a to 2c, the contact charging members 2a to 2c are used.
Is applied with an alternating current of 1.3 mA or less (preferably 0.7 to 1.3 mA). As a result, the surface of the electrophotographic photosensitive member can be charged sufficiently uniformly and without leakage,
Further, it is possible to sufficiently prevent the deterioration of the surface of the electrophotographic photosensitive member in the overlapping portion of the charged regions. When the alternating current value is less than 0.7 mA, it becomes difficult to uniformly charge the surface of the electrophotographic photosensitive member 1, and fog tends to occur in the obtained image.

The frequency at which the alternating current is applied to the contact charging members 2a to 2c is preferably 400 to 2000 Hz. If the frequency is less than 400 Hz, the surface of the electrophotographic photosensitive member is non-uniformly charged and fog tends to occur. On the other hand, if the frequency exceeds 2000 Hz, vibration noise tends to occur.

The contact charging members 2a to 2c shown in FIGS. 1 and 2A and 2B can rotate at the same peripheral speed as the electrophotographic photosensitive member 1 when brought into contact with the electrophotographic photosensitive member 1. However, each of the contact charging members 2a to 2c may be provided with a predetermined driving means and rotated at a peripheral speed different from the peripheral speed of the electrophotographic photosensitive member 1.

An electrostatic latent image is formed by irradiating the surface of the electrophotographic photosensitive member 1 thus charged with the exposure light from the exposure device 3. The exposure device 3 includes a semiconductor laser and an LED (light emitting diode).
e), an optical system device such as a liquid crystal shutter can be used.

Next, the electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed by the developing device 4 to form a toner image. As the developing device 4, a conventionally known developing means using a regular or reversal developer such as a one-component system or a two-component system can be used. Further, the shape of the toner used is not particularly limited, and for example, an irregular toner by a pulverization method or a spherical toner by a polymerization method is preferably used.

The toner image on the surface of the electrophotographic photosensitive member 1 is transferred to the transfer medium P by the transfer device 5. Examples of the transfer device 5 include a contact type transfer charger using a belt, a roller, a film, a rubber blade, etc., a scorotron transfer charger using corona discharge, a corotron transfer charger, etc. It is preferable to use a contact type transfer charger.

This transfer medium P is conveyed to the image fixing device 6, and the toner image is fixed on the transfer medium by heating or pressurization and is printed out.

On the other hand, since the residual toner is usually attached to the surface of the electrophotographic photosensitive member 1 after the transfer step, the cleaning device 7 removes the residual toner. The electrophotographic photosensitive member 1 thus cleaned is repeatedly subjected to the above image forming process. The cleaning device 7 includes a cleaning blade, brush cleaning,
Although roll cleaning or the like can be used, it is preferable to use a cleaning blade among these. Further, examples of the material of the cleaning blade include urethane rubber, neoprene rubber, silicone rubber and the like.

As described above, in the first embodiment, the contact charging members 2a to 2c are arranged in a direction perpendicular to the moving direction of the surface of the electrophotographic photosensitive member 1 so that the ends of the charging regions of the adjacent contact charging members overlap. And the AC current applied to each of the contact charging members 2a to 2c is 1.3.
By setting the current to mA or less, a long electrophotographic photoreceptor 1
Can be charged sufficiently uniformly and without leakage, and deterioration of the electrophotographic photosensitive member 1 in the overlapping portion of the charged regions can be sufficiently prevented. Therefore, it is possible to obtain excellent image quality for a long period of time without causing a phenomenon in which toner adheres to the overlapping portion to disturb the image or a phenomenon in which the charging characteristic of the overlapping portion is deteriorated and fogging occurs.

Next, the second embodiment of the image forming apparatus of the present invention
An embodiment will be described. FIG. 3 is a schematic cross-sectional view showing the electrophotographic photosensitive member 1 according to the second embodiment. In FIG. 3, an undercoat layer 22, a charge generation layer 23, and a charge transport layer 24 are provided on the outer peripheral surface of a conductive substrate 21. The photosensitive layer 20 is formed by laminating in this order, and the thickness of the charge transport layer 24 is 2
It is set to 4 μm or less. The second embodiment is
The electrophotographic photosensitive member 1 to be used is different from the first embodiment in that it has the above-mentioned specific structure, but the other structures (contact charging member, etc.) are the same as those in the first embodiment.

In the electrophotographic photosensitive member 1 shown in FIG. 3,
The conductive substrate 21 usually has a diameter of 10 to 30 m.
A cylindrical body having m and a length of 250 to 1500 mm is used. The material of the conductive substrate 21 is a metal material such as aluminum, stainless steel or nickel; a polymer material such as polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon, polystyrene or phenol resin, or an insulating material such as hard paper. Examples thereof include those in which a substance is dispersed and subjected to conductive treatment; those in which a metal foil is laminated on the above-mentioned insulating material; those in which a metal vapor deposition film is formed on the above-mentioned insulating material.

The conductive substrate 21 is anodized,
It may be subjected to surface treatment such as rough grinding treatment or honing treatment. By such a surface treatment, the surface roughness of the conductive substrate is within a predetermined range (preferably Ra is 0.
The optical interference can be prevented by setting the Rmax to 0.5 to 0.5 μm and the Rmax to 0.5 to 5 μm.

On the inner peripheral surface of the conductive substrate 21, metal,
Vibration noise can be suppressed by fitting a member formed by processing resin, rubber, or the like into a cylindrical shape or a cylindrical shape.

The undercoat layer 22 is formed by containing a predetermined resin. Examples of such resin include acrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin. And the like, and a zirconium compound, a titanium compound or the like may be blended with these resins to form the undercoat layer. The thickness of the undercoat layer is preferably 0.1 to 3.0 μm.

When the subbing layer is provided on the conductive support as described above, the following effects (i) to (vi) can be obtained. (I) The unnecessary carrier injection from the conductive support to the photosensitive layer is prevented to improve the image quality; (ii) The environmental dependence (temperature, humidity, etc.) of the light decay curve of the electrophotographic photoreceptor is reduced. Stable image quality is obtained. (Iii) Due to the appropriate charge transporting ability, the charge is not accumulated even when it is repeatedly used for a long period of time, and the sensitivity fluctuation is suppressed. (Iv) The charge voltage is appropriate. The pressure resistance prevents the occurrence of image defects due to dielectric breakdown; (v) the photosensitive layer can be integrally held on the support as an adhesive layer; (vi) the light reflection of the support is prevented. To be done.

The charge generating layer 23 is formed by including a charge generating substance and a binder resin, and the charge generating substance is dispersed in the binder resin and held in the layer. Specific examples of the charge generating substance include azo pigments, disazo pigments,
Examples thereof include quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, pyrylium salts, azurenium salts, and trigonal selenium. Further, as the binder resin, polycarbonate, polyacrylate, polystyrene, polymethacrylic acid ester, styrene-methyl methacrylate copolymer, polysulfone, polyvinyl acetate, polyacrylonitrile, polyvinyl butyral,
Polyvinylpyrrolidone, methyl cellulose, hydroxymethyl cellulose, cellulose esters and the like can be used. The film thickness of the charge generation layer 23 is preferably 0.05 to 1.0 μm.

The charge transport layer 24 is formed by containing a charge transport substance and a binder resin, and the charge transport substance is dispersed in the binder resin and held in the layer. Specific examples of the charge transport material include polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, and coronene, or derivatives thereof, indole, carbazole, oxazole,
Examples thereof include nitrogen-containing heterocyclic compounds or their derivatives such as isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, and triazole, and hole transporting substances such as hydrazone. As the binder resin, the resin exemplified in the above description of the charge generation layer can be used.

The thickness of the charge transport layer 24 is 24 μm or more as described above, preferably 26 to 40 μm. When the film thickness of the charge transport layer 24 is less than 24 μm, when charged by the charging member 2 described later, a phenomenon in which toner adheres to an overlapping portion and an image is disturbed, or a charging characteristic of the overlapping portion deteriorates to cause fogging. The phenomenon that occurs tends to occur, and sufficient image quality cannot be obtained.

When the undercoat layer 22, the charge generating layer 23 and the charge transporting layer 24 are formed, a (binder) resin or a charge generating substance or a charge transporting substance is dispersed in a predetermined solvent. It can be suitably obtained by applying the coating liquid on a predetermined layer (conductive support, undercoat layer, charge generation layer, etc.) and drying. As such a solvent, a solvent having a high exhibiting property and a vapor density higher than that of air is preferable, and specifically, n-butylamine, diethylamine, ethylenediamine, isopropaholamine,
Triethanolamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, 4-methoxy-4-methylpentanone,
Dimethoxymethane, dimethoxyethane, 2,4-pentadione, anisole, methyl 3-oxobutanoate, monochlorobenzene, toluene, xylene, chloroform, 1,
2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, 1-butanol, ethyl acetate, butyl acetate,
Examples thereof include dimethyl sulfoxide, methyl cellosolve, ethyl cellosolve, methyl cellosolve, and methyl cellosolve acetate. These organic solvents may be used alone or in combination of two or more.

Further, as a method of dispersing the binder resin, the charge transport material, the charge generating material and the like in these solvents, a sand mill, a colloid mill, an attritor, a ball mill, a dyno mill, a high pressure homogenizer, an ultrasonic disperser, Examples include coball mills and roll mills.

As a method of applying the above-mentioned coating liquid, a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method,
Bead coating method, air knife coating method,
Curtain coating method and the like can be mentioned.

When the electrophotographic photosensitive member 1 having the above-mentioned structure is applied to the image forming apparatus shown in FIG. 1 and an image is formed by the apparatus, charging, exposure, development and development are carried out in the same manner as in the first embodiment. Processes such as transfer, image fixing, and cleaning are performed. At this time, the charge generation layer 2 is formed on the conductive substrate 21.
3 and the surface of the electrophotographic photosensitive member 1 on which the charge transport layer 24 having a film thickness of 24 μm or more is laminated in this order so that the end portions of the charging regions of the adjacent contact charging members overlap. By charging with the contact charging members 2a to 2c distributed along the direction orthogonal to the moving direction of the electrophotographic photosensitive member 1, the surface of the electrophotographic photosensitive member 1 can be charged sufficiently uniformly and without leakage, and the charged area It is possible to sufficiently prevent the deterioration of the surface of the electrophotographic photosensitive member 1 in the overlapping portion. Therefore, even if the electrophotographic photosensitive member 1 is long, the phenomenon that the toner adheres to the overlapping portion to disturb the image,
It is possible to obtain excellent image quality for a long period of time without causing a phenomenon in which the charging property of the overlapping portion is deteriorated and fogging occurs.

In the second embodiment, the AC current value applied to each of the contact charging members 2a to 2c is not particularly limited and is not necessarily 1.3 mA or less, but the AC current value is 1 or less. When it is 0.3 mA or less, it is possible to more reliably prevent the phenomenon that the toner adheres to the overlapped portion and the image is disturbed, and the phenomenon that the charging characteristic of the overlapped portion is deteriorated and the fog occurs, which further improves the image quality. Can be made.

The first and second embodiments are not limited to this. For example, the image forming apparatus shown in FIG. 1 includes three contact charging members 2a to 2c, but the number of contact charging members is appropriately determined according to the size of the electrophotographic photosensitive member and the processability of the contact charging members. Can be selected.

Further, as the electrophotographic photoreceptor 1 according to the above-mentioned embodiment, one having a surface protective layer on the photosensitive layer may be used. As a result, deterioration of the surface of the electrophotographic photosensitive member can be prevented more reliably, and the image quality can be further improved. As such a surface protective layer,
A layer in which semiconductive fine particles such as titanium oxide and a low molecular weight compound having a charge transporting ability are dispersed in a binder resin, and an optical functional polymer compound having a charge transporting ability (for example, JP-A-9-
190004, Japanese Patent Laid-Open No. 11-38656,
Examples thereof include layers containing an organic silicon compound described in JP-A No. 2000-171990.

Further, the apparatus shown in FIG. 1 directly transfers the toner image formed on the surface of the electrophotographic photosensitive member 1 to the transfer medium P, but the image forming apparatus of the present invention further comprises an intermediate transfer member. It may be provided. As a result, the toner image on the surface of the electrophotographic photosensitive member 1 can be transferred to the intermediate transfer member and then transferred from the intermediate transfer member to the transfer medium P. As such an intermediate transfer member, one having a structure in which an elastic layer containing rubber, elastomer, resin, etc. and at least one clothing layer are laminated on a conductive support can be used.

[0047]

EXAMPLES The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 (Production of Electrophotographic Photosensitive Member) Length 965 m in central axis direction
m, inner diameter φ78 mm, and outer diameter φ84 mm, a cylindrical aluminum substrate was subjected to honing treatment to obtain Ra0.
The surface was roughened to 2 μm. Then, brush cleaning using a surfactant and cleaning with pure water were sequentially performed and dried at 135 ° C. for 5 minutes. Furthermore, cooling air at 24 ° C. was blown onto the surface of this substrate at 10 m / sec for 5 minutes.

Next, 4 parts by weight of polyvinyl butyral resin (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.) was dissolved.
170 parts by weight of butyl alcohol, organic zirconium compound (acetylacetone zirconium butyrate) 20
By weight, 10 parts by weight of an organic silane compound (γ-aminopropyltrimethoxysilane) were mixed and stirred to prepare a coating liquid for the undercoat layer. This coating solution was applied to the outer peripheral surface of the above substrate, air-dried at room temperature for 5 minutes, heated to 50 ° C. in 10 minutes, and placed in a constant temperature and humidity chamber at 50 ° C. and 85% RH. Moisture hardening promotion treatment was performed for 20 minutes. Further, a drying treatment was carried out in a hot air dryer at 150 ° C. for 10 minutes to form an undercoat layer having a film thickness of 1 μm.

Further, a mixture of 15 parts by weight of chlorogallium phthalocyanine as a charge generating material, 10 parts by weight of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar), and 300 parts by weight of n-butyl alcohol was placed in a sand mill. It was dispersed for 4 hours to prepare a coating liquid for the charge generation layer. This coating solution was applied onto the undercoat layer by dip coating and dried to form a charge generation layer having a thickness of 0.2 μm.

Then, N, N'-diphenyl-N, N '
4 parts by weight of -bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine and bisphenol Z
6 parts by weight of a polycarbonate resin (viscosity average molecular weight: 40,000) was dissolved in 80 parts by weight of chlorobenzene to prepare a coating solution for the charge transport layer. This coating liquid was applied onto the charge generation layer using a dip coating device, and dried at 110 ° C. for 40 minutes. Thus, a charge transport layer having a film thickness of 22 μm was formed to obtain an electrophotographic photosensitive member having the structure shown in FIG.

(Production of Image Forming Apparatus) Using the electrophotographic photosensitive member thus obtained, three roller-shaped contact charging members are arranged as shown in FIGS. 2 (a) and 2 (b). ,
An image forming apparatus having the configuration shown in FIG. 1 was produced. An LED was used as the exposure device 3, a one-component developing device was used as the developing device 4, a transfer roller was used as the transfer device 5, a heating roller and a pressure roller were used as the image fixing device, and a polyurethane cleaning blade was used as the cleaning device.

(Image Quality Evaluation Test) In the image forming apparatus thus obtained, the rotational peripheral speed of the electrophotographic photosensitive member was 105 mm / sec, and the alternating current value applied to each contact charging member was 1.3 mA. 10 A0 size prints
A test of printing 0 sheets continuously was conducted. The surface of the electrophotographic photosensitive member after the test conducted under each condition was observed, and the toner adhesion preventive property in the overlapping portion of the charged area was determined according to the following criteria: A: No adhered toner was observed under any condition B: Room temperature No adhered toner was observed under the normal humidity condition, but adhered toner was observed under the high temperature high humidity condition or the low temperature low humidity condition. C: Adhered toner was observed under all conditions. In addition, the image quality of the 100th sheet obtained in the test conducted under each condition is based on the following criteria: A: No fog is observed B: Some fog is observed C: Fog is generated It was evaluated based on what was accepted. Further, for the electrophotographic photosensitive member after the test performed at room temperature and normal humidity, the surface roughness (Ra) and the residual film thickness of the charge transport layer in the overlapping portion of the charged regions were measured. The results obtained are shown in Table 1.

Example 2 An electrophotographic photoreceptor and an electrophotographic photosensitive member were prepared in the same manner as in Example 1 except that the thickness of the charge transport layer was 24 μm and the value of the alternating current applied to the contact charging member was 1.5 mA. An image forming apparatus was produced and an image quality evaluation test was conducted. The results obtained are shown in Table 1.

Example 3 Example 1 except that the thickness of the charge transport layer was 24 μm.
Similarly to the above, an electrophotographic photosensitive member and an image forming apparatus were produced, and an image quality evaluation test was performed. The results obtained are shown in Table 1.

Example 4 An electrophotographic photoreceptor and an electrophotographic photosensitive member were prepared in the same manner as in Example 1 except that the thickness of the charge transport layer was 24 μm and the AC current value applied to the contact charging member was 1.1 mA. An image forming apparatus was produced and an image quality evaluation test was conducted. The results obtained are shown in Table 1.

Example 5 An electrophotographic photoreceptor and an electrophotographic photosensitive member were prepared in the same manner as in Example 1 except that the curtain thickness of the charge transport layer was 30 μm and the AC current value applied to the contact charging member was 1.3 mA. An image forming apparatus was produced and an image quality evaluation test was conducted. The results obtained are shown in Table 1.

Comparative Example 1 An electrophotographic photosensitive member and an electrophotographic photosensitive member were prepared in the same manner as in Example 1 except that the thickness of the charge transport layer was 22 μm and the AC current value applied to the contact charging member was 1.5 mA. An image forming apparatus was produced and an image quality evaluation test was conducted. The results obtained are shown in Table 1.

[0059]

[Table 1]

As shown in Table 1, in the image forming apparatuses of Examples 1 to 5, toner adhesion and fogging due to the deterioration of the overlapping portion of the charged areas were sufficiently prevented,
It was confirmed that good image quality can be obtained even when used for a long period of time.

[0061]

As described above, in the first image forming apparatus of the present invention, the plurality of contact charging members are arranged so that the end portions of the charging areas of the adjacent contact charging members overlap. Even if the electrophotographic photoconductor is long, electrophotography can be achieved by distributing it along the direction perpendicular to the moving direction of the surface and setting the alternating current applied to each of the contact charging members to 1.3 mA or less. The surface of the photoconductor can be charged sufficiently uniformly and without leakage, and deterioration of the surface of the electrophotographic photoconductor at the overlapping portion of the charged regions can be sufficiently prevented.

Further, in the second image forming apparatus of the present invention,
A surface of an electrophotographic photosensitive member, in which a charge generation layer and a charge transport layer having a thickness of 24 μm or more are laminated in this order on a conductive substrate,
The electrophotographic photoreceptor is charged by a plurality of contact charging members distributed along a direction orthogonal to the moving direction of the surface of the electrophotographic photosensitive member such that the ends of the charging regions of the adjacent contact charging members overlap. Even if the length is long, the surface of the electrophotographic photosensitive member can be charged sufficiently uniformly and without leakage, and deterioration of the surface of the electrophotographic photosensitive member in the overlapping portion of the charged regions can be sufficiently prevented. .

As described above, according to the present invention, the phenomenon that the toner adheres to the overlapping portion to disturb the image and the phenomenon that the charging characteristic of the overlapping portion is deteriorated to cause the fog is not generated.
A wide image forming apparatus capable of obtaining excellent image quality for a long period of time is realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present invention.

2A and 2B are views showing the positional relationship between an electrophotographic photosensitive member and a contact charging member in the image forming apparatus shown in FIG. 1, and FIG. 2A is a perspective view, b) is a top view

FIG. 3 is a schematic sectional view showing an electrophotographic photosensitive member according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Electrophotographic photoreceptor, 2a-2c ... Contact charging member, 3 ...
Exposure device, 4 developing device, 5 transfer device, 6 image fixing device, 7 cleaning device, 9 support, 20 photosensitive layer, 21 conductive substrate, 22 undercoat layer, 23 charge generation Layer, 24 ... Charge transport layer.

Claims (3)

[Claims] 1. An electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, exposure means for exposing the surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image. An image forming apparatus comprising: a developing unit that develops the image, and a transfer unit that transfers the developed image to a transfer medium, wherein the charging unit overlaps end portions of charging regions of adjacent contact charging members. As described above, the electrophotographic photosensitive member is provided with a plurality of contact charging members distributed in a direction orthogonal to the moving direction of the surface thereof, and the alternating current applied to each of the contact charging members is 1.3 mA. An image forming apparatus comprising: 2. An electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposing unit that exposes the surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image. An image forming apparatus comprising: a developing unit that develops the image, and a transfer unit that transfers the developed image to a transfer medium, wherein the electrophotographic photosensitive member comprises a conductive substrate, a charge generation layer, and a film. A charge transport layer having a thickness of 24 μm or more is arranged in this order, and the charging unit moves in the moving direction of the surface of the electrophotographic photosensitive member so that the ends of the charging regions of the adjacent contact charging members overlap. An image forming apparatus comprising a plurality of contact charging members distributed along a direction orthogonal to the above. 3. The alternating current applied to each of the contact charging members is 1.3 mA or less,
The image forming apparatus according to claim 2.