JP2001147575A - Electrifying device, electrophotographic device and processing cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying device where electrifying failure due to attaching of conductive magnetic powder in a longitudinal end part of an electrifying brush to a photoreceptor with an electrical force and image failure caused thereby are prevented in electrification of the magnetic brush of the electrophotographic photoreceptor and an electrophotographic device and a processing cartridge provided with the electrifying device. SOLUTION: In the device, a photoreceptor layer 12 and a charge injecting layer 13 on the photoreceptor layer and provided in the electrophotographic photoreceptor 1 and the width where electrifying is carried out by bringing the conductive magnetic powder 23 and 24 applied with voltage of the magnetic brush 2 is shorter at the center in a longitudinal direction of a rotating axis of the electrophotographic photoreceptor than the width of the photoreceptor layer and the width the charge injecting layer of the electrophotographic photoreceptor 1 in the direction of the rotating axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charging device, an electrophotographic device, and a process cartridge.

More specifically, the present invention relates to a charging device that performs charging (including static elimination) by bringing a magnetic brush having conductive magnetic powder to which a voltage is applied into contact with an electrophotographic photosensitive member. The present invention also relates to an electrophotographic apparatus, such as an electrophotographic copying machine / printer, and a process cartridge provided with the charging device.

[0003]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a corona charger has been used as a means for charging an electrophotographic photosensitive member (hereinafter, referred to as a photosensitive member).

[0004] The corona charger is a non-contact type charging means, for example, includes a discharge electrode such as a wire electrode and a shield electrode surrounding the discharge electrode, and has a discharge opening in non-contact with a photoreceptor to be charged. The photosensitive member surface is charged in a predetermined manner by exposing the photosensitive member surface to a discharge current (corona shower) generated by applying a high voltage to the discharge electrode and the shield electrode.

[0005] In recent years, instead of the corona charger, it has advantages such as low ozone and low power. Therefore, a contact charging device, that is, a charging member in which a voltage is applied to a photoreceptor is brought into contact with the photoreceptor. 2. Description of the Related Art Apparatuses for charging a body have been put to practical use.

In particular, a roller charging system using a conductive roller as a charging member is preferably used in terms of charging stability. In a contact charging device of a roller charging type, a conductive elastic roller as a charging member is brought into pressure contact with a photoconductor, and a voltage is applied to the photoconductor to charge the photoconductor.

More specifically, since charging is performed by discharging from the charging member to the photosensitive member, charging is started by applying a voltage equal to or higher than a certain threshold voltage.
For example, in order to charge the OPC photoconductor having a photosensitive layer thickness of 25 μm by pressing the charging roller against the photoconductor, a voltage of about 640 V or more is applied to the charging roller. The surface potential of the photoreceptor starts to rise, and thereafter, the surface potential of the photoconductor rises linearly with a slope of 1 with respect to the applied voltage.
Hereinafter, this threshold voltage is defined as a charging start voltage Vth.

That is, in order to obtain the photosensitive member surface potential Vd required for electrophotography, the charging roller needs Vd + Vth
DC voltage is required. The contact charging system in which only the DC voltage is applied to the contact charging member to charge the photosensitive member in this manner is called a DC charging system.

However, in the DC charging system, the resistance value of the contact charging member fluctuates due to fluctuations in temperature and humidity around the apparatus, and Vth fluctuates when the thickness of the photosensitive layer changes due to abrasion of the photosensitive layer. It was difficult to set the potential of the photoconductor to a desired value.

For this reason, as disclosed in JP-A-63-149669, a DC voltage corresponding to a desired Vd has a peak-to-peak voltage of 2 × Vth or more, as disclosed in JP-A-63-149669. An AC charging system is used in which a photosensitive member is charged by applying an oscillating voltage on which an AC component is superimposed to a contact charging member. This is for the purpose of the leveling effect of the potential by AC, and the potential of the photoconductor converges to Vd,
It is not affected by external factors such as the environment and photoreceptor scraping.

However, even in such a contact charging device, the essential charging mechanism uses a discharging phenomenon from the charging member to the photosensitive member, so that the voltage required for charging is as described above. A value higher than the surface potential of the photoconductor is required, and a small amount of ozone is generated. When the AC charging system is used for uniform charging, the amount of ozone generated further increases, vibration noise (AC charging noise) of the charging member and the photoconductor due to the electric field of the AC voltage, and discharge due to the discharge. This has been a new problem, for example, the deterioration of the photoreceptor surface has been remarkable.

Therefore, as a new charging method, a charging method by directly injecting electric charge into the photosensitive member is disclosed in Japanese Patent Laid-Open No. 6-3921.
No. 6,086,045. In this charging method, a voltage is applied to a contact charging member such as a charging roller, a charging brush, and a charging magnetic brush, and charges are directly injected into charge trap levels of a charge injection layer on the surface of the photoconductor or conductive particles. This is a method of performing charging.

In this charge injection charging system, since no discharge phenomenon is used, the voltage required for charging is only the desired surface potential of the photoconductor, and no ozone is generated. Furthermore, A
Since no C voltage is applied, there is no generation of charging noise, and the charging method is excellent in ozone-less and low power compared to the roller charging method.

[0014]

However, in the above-described charge injection charging method, when a magnetic brush is used as the contact charging member, the conductive magnetic powder at the longitudinal end of the magnetic brush is electrically connected to the photosensitive member. Insufficient charging caused by adhesion by force, and further image defects occurred.

This will be described with reference to a model diagram of the magnetic brush charging device shown in FIG. (A) is a cross-sectional model diagram, (b) is a front model diagram in which an intermediate portion is omitted, and (c) is a vertical cross-sectional model diagram on one end side.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member as a member to be charged, which is rotated at a predetermined peripheral speed in a clockwise direction indicated by an arrow in FIG.

Reference numeral 2 denotes a magnetic brush (magnetic brush charger) as a contact charging member. This embodiment is a sleeve rotating type, in which a non-magnetic electrode sleeve 21 as a magnetic brush holding member, a magnet roller 22 as a magnetic field generating means inserted and arranged in the electrode sleeve 21, and an outer peripheral surface of the electrode sleeve 21 And a magnetic brush portion 23 of a conductive magnetic powder (carrier) 24 which is magnetically constrained and held by the magnetic field of the magnet roller 22 in the sleeve.

The magnetic brush 2 is arranged in parallel with the magnetic brush portion 23 in contact with the photoreceptor 1. n is the magnetic brush portion contact nip portion (charging nip portion).

The magnet roller 22 is fixedly supported in a non-rotating manner, and the electrode sleeve 21 is fixed to the magnet roller 2.
In the charging nip portion n, the photosensitive drum 1 is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow, which is a counter direction. The magnetic brush portion 23, which is magnetically constrained and carried on the outer peripheral surface of the electrode sleeve 21, is also rotationally conveyed with the rotation of the electrode sleeve 21, and rubs the surface of the photoconductor 1 at the charging nip portion n. When a predetermined charging bias is applied from the charging bias applying power source S1 to the magnetic brush unit 23 via the electrode sleeve 21, the outer peripheral surface of the rotating photoconductor 1 is brought to a predetermined surface potential by charge injection charging. Likewise charged.

In the magnetic brush charging device as described above, the longitudinal end portion E (the end of the magnetic brush portion 23) of the magnetic brush 2 in the direction of the rotation axis is formed by the magnetic powder 24 forming the magnetic brush portion 23. In the charging nip portion n, which is a contact portion between the magnetic brush portion 23 and the photoconductor 1, a part is pushed out from the region C to the region D (outside the longitudinal end of the charging nip portion n) in FIG. (Direction of arrow A). In the region D, since the magnetic brush portion 23 is not always in contact with the photoconductor 1, the surface of the photoconductor is hardly charged, and a potential difference is easily generated between the magnetic brush and the surface of the photoconductor.

When this potential difference occurs, the magnetic powder 24 moves from the magnetic brush portion 23 to the photoconductor 1 due to the force in the photoconductor direction B generated by the injection of electric charge from the electrode sleeve into the carrier. This phenomenon is peculiar to a system in which a photosensitive member is injected and charged by a magnetic brush composed of a medium-resistance carrier, and does not occur when the brush is rubbed with a high-resistance magnetic brush or simply a magnetic brush.

In FIG. 3C, when the photosensitive layer and the charge injection layer are not covered up to the region C in the region D, the potential difference between the surface of the photosensitive member and the magnetic brush is further increased. Further movement of the magnetic powder from the brush to the photoreceptor will occur.

In the case of a magnetic brush such as two-component development, the development contrast (the difference between the development potential and the photoconductor surface potential) is generally smaller than the charging contrast (the difference between the charging potential and the photoconductor surface potential). On the other hand, the adhesion of the magnetic powder to the photosensitive member is not so remarkable as when the magnetic brush is used for charging. Further, when a magnetic brush is used for development, toner is present in the magnetic brush, and the toner adheres to the photoconductor before the magnetic powder (carrier). This is because the toner is lighter than the magnetic powder and has a higher resistance and hence a higher retained charge, so that the toner is more likely to adhere to the photoreceptor by an electric force. Therefore, the magnetic powder rarely adheres to the photoconductor.

If the magnetic powder adheres to the photoreceptor during the charging of the magnetic brush, the magnetic powder of the magnetic brush, which is a charging member, gradually decreases, and an image defect due to a charging failure or the like occurs gradually. There was a disadvantage that it could not be used.

Accordingly, an object of the present invention is to provide a magnetic brush for an electrophotographic photoreceptor, in which charging failure caused by the conductive magnetic powder at the longitudinal end of the magnetic brush adhering to the photoreceptor by electric force, It is still another object of the present invention to provide a charging device, an electrophotographic apparatus having the charging device, and a process cartridge which prevent the occurrence of an image defect.

[0026]

According to the present invention, there is provided a charging device, an electrophotographic apparatus and a process cartridge having the following constitution.

(1) In a charging device for charging by contacting a rotatable electrophotographic photosensitive member with a magnetic brush having conductive magnetic powder to which a voltage is applied, the electrophotographic photosensitive member includes a photosensitive layer and the photosensitive layer. A charge injection layer on the electrophotographic photosensitive member, and a width for charging by contacting a conductive magnetic powder to which a voltage is applied is smaller than the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member. A charging device characterized in that the charging device is short with respect to the longitudinal center in the rotation axis direction of the photoreceptor.

(2) The charging device according to (1), wherein the charge injection layer of the electrophotographic photosensitive member contains conductive particles.

(3) The charging device according to (1) or (2), wherein the magnetic brush is a rotatable brush roller.

(4) According to the width of the photosensitive layer and the width of the charge injection layer in the direction of the rotation axis of the electrophotographic photosensitive member, the width of charging of the electrophotographic photosensitive member by contacting the conductive magnetic powder to which a voltage is applied is determined. The charging device according to any one of (1) to (3), wherein the charging device is shorter than the axial center by 3 mm or more.

(5) Image formation is performed by applying an image forming process including a step of charging a rotatable electrophotographic photosensitive member with a magnetic brush having conductive magnetic powder to which a voltage is applied. In the electrophotographic apparatus, the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and a voltage is applied based on the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member. An electrophotographic apparatus, wherein a width of charging by contacting the conductive magnetic powder is short with respect to a longitudinal center in a rotation axis direction of the electrophotographic photosensitive member.

(6) The electrophotographic apparatus according to (5), wherein the charge injection layer of the electrophotographic photosensitive member contains conductive particles.

(7) The electrophotographic apparatus according to (5) or (6), wherein the magnetic brush is a rotatable brush roller.

(8) According to the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photoreceptor, the width of charging of the electrophotographic photoreceptor by contacting the conductive magnetic powder to which a voltage is applied is determined. The electrophotographic apparatus according to any one of (5) to (7), wherein the length is shorter than the axial center by 3 mm or more.

(9) At least an electrophotographic photosensitive member and a charging device for charging the electrophotographic photosensitive member by bringing a magnetic brush having conductive magnetic powder to which a voltage is applied into contact with the electrophotographic photosensitive member are integrally supported, A process cartridge detachable from the main body of the electrophotographic apparatus, wherein the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and a photosensitive layer width and a charge in a rotation axis direction of the electrophotographic photosensitive member. From the injection layer width,
A process cartridge wherein the width of charging by contacting a conductive magnetic powder to which a voltage is applied is short with respect to the longitudinal center of the electrophotographic photosensitive member in the rotation axis direction.

(10) At least an electrophotographic photosensitive member,
The electrophotographic photosensitive member integrally supports a charging device for charging by contacting a magnetic brush having a conductive magnetic powder to which a voltage is applied, and one or both of a developing unit and a cleaning unit. A process cartridge detachable from a photographic apparatus main body, wherein the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and a photosensitive layer width and charge injection in a rotation axis direction of the electrophotographic photosensitive member. A process cartridge, wherein a width of charging by contacting a conductive magnetic powder to which a voltage is applied is shorter than a layer width with respect to a longitudinal center in a rotation axis direction of the electrophotographic photosensitive member.

(11) The process cartridge according to (9) or (10), wherein the charge injection layer of the electrophotographic photosensitive member contains conductive particles.

(12) The process cartridge according to any one of (9) to (11), wherein the magnetic brush is a rotatable brush roller.

(13) According to the width of the photosensitive layer and the width of the charge injection layer in the direction of the rotation axis of the electrophotographic photosensitive member, the width of charging of the electrophotographic photosensitive member by contacting the conductive magnetic powder to which a voltage is applied is determined. The process cartridge according to any one of (9) to (12), wherein the process cartridge is shorter than the axial center by 3 mm or more.

<Operation> That is, the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member are expressed as follows. The end of the magnetic brush at the longitudinal end of the photoconductor in the rotation axis direction is configured such that the width of charging by contacting the conductive magnetic powder to which the voltage is applied is short with respect to the longitudinal center of the electrophotographic photoconductor in the rotation axis direction. Since a potential difference between the photoconductor and the magnetic brush at a position corresponding to the outside hardly occurs, the conductive magnetic powder constituting the magnetic brush does not adhere to the photoconductor by electric force. Therefore, the conductive magnetic powder of the magnetic brush does not decrease, and even in long-term use,
It is possible to obtain a high-quality image without charging failure or the like.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 (FIGS. 1 to 4) (1) Electrophotographic Apparatus FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus of the present embodiment. The electrophotographic apparatus in this embodiment is a laser beam printer using a transfer type electrophotographic process, a magnetic brush charging system, and a process cartridge system.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member having a photosensitive layer and a charge injection layer on the photosensitive layer. This embodiment is an OPC photoconductor (organic photoconductor) having a diameter of 30 mm,
It is driven to rotate at a process speed (peripheral speed) of 100 mm / sec in the clockwise direction indicated by the arrow. The photoconductor 1 will be described in detail in section (2).

Numeral 2 denotes a magnetic brush as a contact charging member which is brought into contact with the rotary photoreceptor 1. This magnetic brush is of the same sleeve rotating type as that of FIG. 10 described above, and the magnetic brush portion 23 of the conductive magnetic powder 24 is formed on the rotatable non-magnetic electrode sleeve 21 by the magnetic force of the magnet roller 22. Magnetically attached. A DC charging bias of -700 V is applied to the magnetic brush 2 from a charging bias application power source S1, and the outer peripheral surface of the photoconductor 1 is uniformly charged to approximately -700V by charge injection charging. The magnetic brush 2 will be described in detail in section (3).

A laser whose intensity is modulated in response to a time-series electric digital pixel signal of target image information output from a laser beam scanner 7 including a laser diode, a polygon mirror, etc., on the charged surface of the photoreceptor 1. The scanning exposure L by the beam is performed, and an electrostatic latent image corresponding to the target image information is formed on the peripheral surface of the photoconductor 1.

The electrostatic latent image is developed as a toner image by a reversal developing device 3 using a magnetic one-component insulating toner.
Reference numeral 3a denotes a non-magnetic developing sleeve having a diameter of 16 mm and containing the magnet 3b. The developing sleeve is coated with the above-mentioned negative toner, and the distance from the surface of the photoconductor 1 is set to 300 μm.
In this state, the photosensitive drum 1 is rotated at the same speed as the photosensitive member 1, and a developing bias voltage is applied to the developing sleeve 3a from a developing bias power source S2. A voltage obtained by superimposing a DC voltage of -500 V and a rectangular AC voltage having a frequency of 1800 Hz and a peak-to-peak voltage of 1600 V is used.
Jumping development is performed between the two.

On the other hand, a transfer material P as a recording material is fed from a paper feeding unit (not shown), and the photosensitive member 1 is brought into contact with the photosensitive member 1 with a predetermined pressing force, so that a medium transfer medium P having a medium resistance is used. It is introduced at a predetermined timing into a pressure contact nip (transfer portion) T with the transfer roller 4. A predetermined transfer bias voltage is applied to the transfer roller 4 from a transfer bias application power source S3. In this embodiment, transfer was performed by applying a DC voltage of +2000 V using a roller having a roller resistance of 5 × 10 ⁸ Ω · cm.

The transfer material P introduced into the transfer section T is conveyed by nipping the transfer section T, and the toner image formed and carried on the surface of the photoreceptor 1 on its surface side is sequentially reduced by electrostatic force and pressing force. Is transcribed.

The transfer material P to which the toner image has been transferred is separated from the surface of the photoreceptor 1 and introduced into a fixing device 5 such as a heat fixing system, where the toner image is fixed and an image formed product (print, copy) is formed. Is discharged out of the apparatus.

After the transfer of the toner image onto the transfer material P, the surface of the photoreceptor is cleaned by the cleaning device 6 to remove the adhered contaminants such as residual toner, and is repeatedly used for image formation.

In the printer of this embodiment, four process devices such as a photoreceptor 1, a magnetic brush 2, a developing device 3 and a cleaning device 6 are enclosed in a cartridge 20 and can be detached and replaced collectively with respect to the printer main body. It is a cartridge type device, but is not limited to this.

Here, the process cartridge is a unit in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is detachably mountable to an image forming apparatus main body.
In addition, at least one of the charging means, the developing means, and the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge, and this cartridge is made detachable from the image forming apparatus main body. Further, at least the developing means and the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge is detachably mountable to the main body of the image forming apparatus.

Reference numeral 10 denotes a process cartridge attaching / detaching guide / holding member on the printer body side.

(2) Electrophotographic Photoreceptor 1 The electrophotographic photoreceptor 1 used in the present invention is not particularly limited as long as it is a photoreceptor in which a photosensitive layer and a charge injection layer are laminated in this order.

The photosensitive layer has a single-layer structure or a laminated structure.
In the case of a single-layer structure, both a charge generating substance and a charge transporting substance are contained in the same layer. In the case of a stacked structure, a charge generation layer for generating photocarriers and a charge transport layer for moving carriers are stacked. The surface layer may be formed on either the charge generation layer or the charge transport layer.

FIG. 2A is a model diagram of an example of a layer structure of a photosensitive member using a photosensitive layer having a single-layer structure. In order from the bottom, a conductive support 11, a photosensitive layer (single-layer structure) 12, Charge injection layer 13
. (B) is a model diagram of a layer configuration example of a photoreceptor using a photosensitive layer having a laminated structure, in which a conductive support 11, a charge generation layer 12a, a charge transport layer 12b, and a charge injection layer 13 are laminated in order from the bottom. Consists of The charge generation layer 12a and the charge transport layer 12b constitute the photosensitive layer 12 having a laminated structure. As shown in (c), the conductive support 11 and the photosensitive layer 12 (1
2a and 12b) may be provided with an undercoat layer 11a.

A) Conductive Support 11 The conductive support 11 is made of a metal or alloy such as iron, copper, nickel, aluminum, titanium, tin, antimony, indium, lead, zinc, gold, silver, or an oxide thereof. Materials, carbon, conductive resins, and the like can be used. The shape includes a cylindrical shape, a belt shape, and a sheet shape. The conductive material may be molded, but may be applied as a paint or may be deposited.

B) Undercoat Layer 11a When an undercoat layer 11a is provided between the conductive support 11 and the photosensitive layer 12 (12a, 12b), the undercoat layer 11a is mainly composed of a binder resin. It may contain a conductive material or an acceptor.

As the binder resin for forming the undercoat layer, for example, polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene,
Examples thereof include polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyallyl ether, polyacetal, phenolic resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, and butyral resin.

C) Photosensitive Layer 12 In the photosensitive layer 12 having a single-layer structure, the charge generation material and the charge transport material are contained in an amount of 20 to 80% by mass, more preferably 30 to 80% by mass.
７０70% by mass. The single-layer photosensitive layer has a thickness of 5 to 100 μm.
m, more preferably 10-60 μm
It is.

In the photosensitive layer 12 having a laminated structure, the thickness of the charge generation layer 12a is 0.001 to 6 μm, more preferably 0.01 to 2 μm. The amount of the charge generating material is 10 to 1
00 mass%, more preferably 40 to 100 mass%. The thickness of the charge transport layer 12b is 5 to 100 μm, more preferably 10 to 60 μm. The amount of charge transport material is 2
It is 0 to 80% by mass, and more preferably 30 to 70% by mass.

Examples of the charge generating material include phthalocyanine pigments, polycyclic quinone pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium salt dyes, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes, Examples include quinone imine dyes, triphenylmethane dyes, styryl dyes, selenium, selenium-tellurium, amorphous silicon, and hardened cadmium.

Examples of charge transport materials include pyrene compounds, carbazole compounds, hydrazone compounds, N, N
-Dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, styryl compounds, stilbene compounds and the like.

The coating method of the photoreceptor employs a method such as spray coating, beam coating and dip coating.

Further, additives such as an antioxidant and an ultraviolet absorber may be added to the photoreceptor as needed.

D) Charge injection layer 13 The charge injection layer 13 is made of a metal such as gold, silver and copper;
Metal oxides such as zinc oxide, indium oxide, titanium oxide and antimony oxide; conductive particles 14 such as conductive polymers such as polythiophene, polyaniline and polyacetylene
Is contained in a binder resin.
It is also constituted by including an electron-accepting compound in a binder resin. The film thickness can be 0.01-20 μm, more preferably 0.1-10 μm.

The charge injecting layer 13 contains a charge generating material, a charge transporting material, etc. in addition to the above-mentioned metals and their oxides, nitrides, salts, alloys, conductive materials such as carbon, and electron-accepting compounds. May be.

The electron-accepting compounds usable here are:
The reduction potential measured using the calomel electrode as a reference electrode is 0.
Compounds having a voltage of 5 V or less, such as tetracyanoquinodimethane, trinitrofluorenone, and chloranil. The method for measuring the reduction potential is as follows.

[0068] The reduction potential measuring method: a reference electrode saturated calomel electrode, 0.1N-(n-butyl) ₄ N ⁺ ClO ₄ ^-
Using an acetonitrile solution, the potential of the working electrode was swept by a potential sweeper, and the peak position of the obtained current-potential curve was directly obtained as the value of the reduction potential.

[0069] Specifically, the sample 0.1N-(n-butyl) ₄ N ⁺ ClO ₄ ^- 1 to the electrolytic solution in acetonitrile
Dissolve to a concentration of about 0 mm 1%. Then, a voltage is applied to the sample solution by the working electrode,
A current change when a voltage is linearly changed from a high potential (0 V) to a low potential (-1.0 V) is measured to obtain a current-potential curve. The absolute value of the potential value that reached the current peak (the highest potential side in the case of a plurality of peaks) in this current-potential curve was defined as the reduction potential.

As the binder resin used for the charge injection layer, for example, polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene,
Examples thereof include polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyallyl ether, polyacetal, phenolic resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, and butyral resin. Furthermore, reactive epoxy and (meth) acrylic monomers and oligomers can be used after mixing and curing.

E) Photoconductor used in this embodiment The electrophotographic photoconductor 1 in this embodiment is an OPC for negative charging.
It is a photoreceptor (organic photoreceptor) and is manufactured in the following manner.

[0072] Conductive support 11 Conductive titanium oxide 10 parts by mass (tin oxide coating, average primary particle size 0.4 μm) Phenol resin precursor (resole type) 10 parts by mass methanol・ 10 parts by mass butanol ・ ・ ・ ・ ・ 10 parts by mass was dispersed in a sand mill, and then the outer diameter was 30 mm and the length was 35
Dip coating on a 7.5 mm aluminum cylinder
By curing at 40 ° C, volume resistance 5 × 10 ⁹ Ω · c
m, a conductive layer having a thickness of 20 μm was provided.

.. Subbing layer 11 The following methoxymethylated nylon (degree of methoxymethylation: about 30%) 10 parts by mass

[0074]

Embedded image

After mixing and dissolving 150 parts by mass of isopropanol, dip coating was performed on the conductive layer, and 1 μm
m undercoat layer was provided.

. Next, the diffraction angle 2 in the X-ray diffraction spectrum of CuKα
θ ± 0.2 ° is 9.0 °, 14.2 °, 23.9 °, 2
After 4 parts by mass of TiOPc having a strong peak at 7.1 °, 2 parts by mass of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical) and 6 parts by mass of cyclohexanone were dispersed for 4 hours by a sand mill using φ1 mm glass beads. 100 parts by mass of ethyl acetate was added to prepare a dispersion for a charge generation layer. This was applied by dip coating.
A 3 μm charge generation layer was provided.

[0077]. Charge transport layer 12b Triphenylamine described below 10 parts by mass

[0078]

Embedded image

Polycarbonate resin (Bisphenol Z, Molecular Nose 20000) 10 parts by mass Monochlorobenzene 50 parts by mass Dichloromethane 5 parts by mass Dip coating on the layer
A 7 μm charge transport layer was provided.

.. Charge injection layer 13 Finally, as a charge injection layer on the surface, an acrylic monomer represented by the following structural formula: 30 parts by mass

[0081]

Embedded image

Ultrafine tin oxide particles having an average particle size of 40 nm before dispersion: 50 parts by mass Polytetrafluoroethylene resin fine powder (average particle size: 0.18 μm) 50 parts by mass Photopolymerization started ... 18 parts by mass of ethanol ... 150 parts by mass of ethanol were dispersed in a sand mill for 66 hours to prepare a dispersion for a charge injection layer. A film is formed by dip coating on the transport layer, photocured at a light intensity of 800 mW / cm ² for 60 seconds with a high-pressure mercury lamp, and then dried at 120 ° C. for 2 hours with hot air to obtain a film thickness of 3 μm.
Was provided.

(3) Magnetic Brush 2 In charge injection charging, charge injection properties and charging uniformity greatly depend on the shape and resistance of the contact charging member. In order to obtain sufficient charge injecting property and uniform charging, it is important to make sufficient contact between the contact charging member and the surface of the photoreceptor.
Is very good.

The charge injection charging is to charge a photosensitive member surface having a medium resistance surface resistance by a medium resistance contact charging member, and to conduct conductive particles or traps in a charge injection layer on the photosensitive member surface. This is a method in which a charge is charged to a charge or electron accepting compound to perform charging.

Specifically, FIG. 3 shows that a photosensitive layer 12 is formed on a conductive support (aluminum support) 11 as a photosensitive member 1.
Further, an equivalent circuit model diagram of an example in which a charge injection layer 13 in which tin oxide fine particles 14 are dispersed / contained thereon is used is shown.

This is based on the theory that the magnetic brush 2 charges a small capacitor with the photosensitive layer 12 as a dielectric and the aluminum support 11 and the conductive particles 14 in the charge injection layer 13 as both electrode plates. is there.

At this time, the conductive particles 14 are electrically independent of each other and form a kind of minute float electrode. For this reason, macroscopically, the photoreceptor surface appears to be charged and charged to a uniform potential, but in reality there are situations where countless minutely charged conductive particles cover the photoreceptor surface. Has become. For this reason, even if image exposure L is performed by the laser, each conductive particle 14 is electrically independent, so that an electrostatic latent image can be held.

In order to form a magnetic brush, conductive magnetic powder such as magnetite and ferrite is arranged in a brush shape around a magnet bar. The smaller the particle size of the magnetic powder, the better the charge injecting property. However, if the particle size is too small, the movement and adhesion of particles from the magnet to the surface of the photoreceptor increase. Therefore, the particle size is preferably 0.1 to 50 μm, and 1 to 30 μm
Is more preferred.

The relationship between the electric resistance of the magnetic brush 2 and the charging performance is such that if the resistance of the magnetic brush is too high, charging failure occurs, and if the resistance is too low, charging failure around the pinhole and enlargement of the pinhole occur. Electric breakdown of the magnetic brush occurs. In the present invention, the electric resistance of the magnetic brush ranges from 1 × 10 ⁴ to
Particularly good chargeability was obtained at 1 × 10 ⁷ Ω · cm.

The electric resistance of the magnetic brush at this time was set to a nip width of 3 on a metal drum of φ30 and length of 250 mm.
mm, and converted from the current value flowing when a voltage of 100 V was applied.

Further, by rotating the magnetic brush 2 with a peripheral speed difference with respect to the photosensitive member 1, the contact between the brush and the photosensitive member surface is increased, and the charge injection property can be improved.

As described above, the magnetic brush 2 of this embodiment is a sleeve rotating type, and the magnetic brush portion 23 of the conductive magnetic powder 24 is attached to the rotatable non-magnetic electrode sleeve 21 by the magnetic force of the magnet roller 22. Formed and adhered. The magnetic flux density by the magnet roller 22 on the electrode sleeve is 800 × 10 ⁻⁴ T (tesla).

The magnetic brush portion 23 of the magnetic powder 24 on the charging sleeve 21 is coated with a thickness of 1 mm to form a charging nip portion n having a width of about 5 mm between the magnetic brush 24 and the photosensitive member. It is in contact with the photoreceptor surface while rotating (counter direction with respect to the photoreceptor surface). In this embodiment, the amount of magnetic powder of the magnetic brush is about 10 g, and the gap at the charging nip portion n between the electrode sleeve 21 and the photosensitive member 1 is 500 μm.

Here, the peripheral speed ratio between the magnetic brush and the photosensitive member is defined by the following equation.

Peripheral speed ratio% = (magnetic brush peripheral speed−photosensitive member peripheral speed) / photosensitive member peripheral speed × 100 * The peripheral speed of the magnetic brush is a negative value in the case of counter rotation. Since the magnetic brush is stopped, the shape of the magnetic brush stopped on the surface of the photoreceptor directly results in poor charging and appears on an image. In the forward rotation, if the same peripheral speed ratio as that in the counter direction is to be obtained, the number of rotations of the magnetic brush increases. When the magnetic brush contacts the photoconductor at a low speed in a forward rotation, the magnetic powder of the magnetic brush easily adheres to the photoconductor. Therefore, the peripheral speed ratio is preferably -100% or less, and in this embodiment, it is -150%.
%.

The conductive magnetic powder 24 constituting the magnetic brush is as follows: a resin and a magnetic powder such as magnetite are kneaded and formed into particles, or conductive carbon is added thereto to adjust the resistance value. Mixed ・ Sintered magnetite, ferrite, or those whose resistance has been adjusted by reducing or oxidizing them ・ Coating material whose resistance has been adjusted with the above magnetic powder (such as phenolic resin with carbon dispersed) With coat or N
For example, the resistance value may be adjusted to an appropriate value by plating with a metal such as i.

If the resistance value of these magnetic powders is too high, charges cannot be uniformly injected into the photoreceptor, resulting in a fog image due to minute charging failure. If the temperature is too low, when there is a pinhole on the surface of the photoreceptor, current concentrates on the pinhole and the charging voltage drops, so that the surface of the photoreceptor cannot be charged. Therefore, the resistance value of the magnetic powder 24 is 1 × 10 ⁴ to 1 × 10 ⁸ Ω · c.
m is desirable.

The resistance value of the magnetic powder is determined by placing 2 g of the magnetic powder in a metal cell (bottom area of 227 mm ² ) to which a voltage can be applied, applying 6.6 kg / cm ² and applying a voltage of 1 to 1000 V.
It was measured by applying voltage.

Regarding the magnetic properties of the magnetic powder, it is better to increase the magnetic binding force in order to prevent the magnetic powder from adhering to the photoreceptor, and the saturation magnetization is desirably 50 (A · m ² / kg) or more. .

The magnetic powder 24 actually used in this embodiment is
The average particle size is 30 μm, the resistance value is 1 × 10 ⁶ Ω · cm,
The saturation magnetization was 58 (A · m ² / kg).

(4) Arrangement for Preventing Adhesion of Magnetic Powder In this embodiment, the coating width of the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 in the rotation axis direction of the photosensitive member and the magnetic brush 2
The end portion E of the magnetic brush portion 23 maintains the relationship shown in the model diagram of FIG. 4, and is 3.5 mm longer than the end portion E of the magnetic brush portion 23 in the rotation axis direction of the magnetic brush 2 with respect to the longitudinal center.
The photosensitive layer 12 and the charge injection layer 13 were applied to the outside.

That is, the width of the magnetic brush portion 23 (the width for charging by contacting the magnetic powder to which a voltage is applied) is larger than the width of the photosensitive layer 12 and the width of the charge injection layer 13 in the rotation axis direction of the photoconductor 1. ) Is 3.5 mm shorter than the longitudinal center of the photosensitive member 1 in the rotation axis direction.

As described above (FIG. 10), the magnetic powder of the magnetic brush, which has conventionally been pushed outward in the longitudinal direction where the surface of the photosensitive member has not reached the charging potential at the charging nip, is replaced by the charge injected into the magnetic powder. Although the photoreceptor adhered to the photoreceptor by the electric force of the present embodiment, the configuration of this embodiment reduces the electric field between the magnetic powder and the photoreceptor, and the magnetic powder adheres to the photoreceptor by the electric force. Was almost prevented. When 10,000 images were repeatedly output by the printer of this embodiment, a good image could be output.

<Embodiment 2> (FIG. 5) In this embodiment, the coating width of the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 in the rotation axis direction of the photosensitive member and the magnetic brush 2
The end portion E of the magnetic brush portion 23 maintains the relationship shown in the model diagram of FIG. 5, and the photosensitive layer 12 is longer than the end portion E of the magnetic brush portion 23 in the rotation axis direction of the magnetic brush 2 with respect to the longitudinal center. In the same manner as in the first embodiment, the charge injection layer 13 is extended to 3.5 mm outside the end E of the magnetic brush portion 23 in the rotation axis direction of the magnetic brush 2 on the basis of the longitudinal center. Applied.

That is, the width of the magnetic brush portion 23 is smaller than the width of the photosensitive layer 12 in the rotation axis direction of the photoconductor 1 and the width of the charge injection layer 13 with respect to the lengthwise center of the photoconductor 1 in the rotation axis direction. 5 mm, and 3.5 mm shorter than the charge injection layer 13.

The other printer configurations and conditions are the same as in the first embodiment. Also in the case of the printer of this embodiment, a good image could be output when 10,000 images were repeatedly output.

<Embodiment 3> (FIG. 6) In this embodiment, the coating width of the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 in the rotation direction of the photosensitive member and the magnetic brush 2
The end E of the magnetic brush portion 23 maintains the relationship shown in the model diagram of FIG. 6, and the photosensitive layer 12 has the magnetic brush portion in the rotation axis direction of the magnetic brush 2 as in the case of the first embodiment. 3.5 mm on the basis of the longitudinal center from the end E of 23
The charge injection layer 13 was applied to the outside by 2 mm from the end E of the magnetic brush portion 23 in the rotation axis direction of the magnetic brush 2 on the basis of the longitudinal center.

That is, the width of the magnetic brush portion 23 is smaller than the width of the photosensitive layer 12 in the rotation axis direction of the photosensitive member 1 and the width of the charge injection layer 13 with respect to the photosensitive layer 12 with respect to the longitudinal center of the rotation direction of the photosensitive member 1. The relationship between the charge injection layer 13 and the charge injection layer 13 is shorter by 3.5 mm.

Other configurations and conditions of the printer are the same as those in the first embodiment. Also in the case of the printer of this embodiment, a good image could be output when 10,000 images were repeatedly output.

However, the surface of the photoreceptor was observed after repeated image output, and it was confirmed that the magnetic powder adhered to a portion that was at least 2 mm outside the end E of the magnetic brush portion in the direction of the magnetic brush rotation axis with respect to the longitudinal center. .

<Embodiment 4> (FIG. 7) In this embodiment, the coating width of the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 in the rotation direction of the photosensitive member and the magnetic brush 2
The end portion E of the magnetic brush portion 23 maintains the relationship shown in the model diagram of FIG. 7, and the photosensitive layer extends 2 mm outside the end portion E of the magnetic brush portion 23 in the rotation axis direction of the magnetic brush 2 with respect to the longitudinal center. 12 and the charge injection layer 13 were applied.

That is, the width of the magnetic brush portion 23 is 2 m longer than the width of the photosensitive layer 12 and the width of the charge injection layer 13 in the rotation axis direction of the photosensitive member 1 with respect to the longitudinal center of the photosensitive member 1 in the rotation axis direction.
The relationship is short.

The other printer configurations and conditions are the same as in the first embodiment. Also in the case of the printer of this embodiment, a good image could be output when 10,000 images were repeatedly output.

However, when the surface of the photoreceptor was observed after repeated image output, it was confirmed that the magnetic powder was adhered to a portion that was at least 2 mm outside the end E of the magnetic brush portion in the direction of the magnetic brush rotation axis on the basis of the longitudinal center. .

<Comparative Example 1> (FIG. 8) In the case of this comparative example, as shown in the model diagram of FIG. 8, the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 were coated in the rotation direction of the photosensitive member. The width was set at the same position as the end portion E of the magnetic brush portion in the magnetic brush rotation axis direction. Other configurations and conditions of the printer are the same as those of the first embodiment.

When images were repeatedly formed, remarkable adhesion of magnetic powder occurred on the surface of the photosensitive member, which was outside the longitudinal center of the end portion E of the magnetic brush portion in the direction of the magnetic brush rotation axis, and after 2000 images were formed. In this case, the magnetic powder in the charging member was insufficient, and image defects such as ground fog occurred due to poor charging.

<Comparative Example 2> (FIG. 9) In the case of this comparative example, as shown in the model diagram of FIG. 9, the coating of the photosensitive layer 12 and the charge injection layer 13 of the photosensitive member 1 in the rotation axis direction of the photosensitive member was performed. The width was set to be 2 mm inward from the end E of the magnetic brush portion in the direction of the magnetic brush rotation axis on the basis of the longitudinal center. Other configurations and conditions of the printer are the same as those of the first embodiment.

When images were repeatedly output, remarkable adhesion of magnetic powder occurred to a portion on the surface of the photoconductor 2 mm outside the inner end of the magnetic brush portion end E in the direction of the magnetic brush rotation axis on the basis of the longitudinal center and 500 mm. After the output of the sheet image, the magnetic powder in the charging member was insufficient, and image defects such as ground fog due to poor charging occurred.

<Others> 1) The present invention is not limited to the embodiment described above.

2) The photoreceptor has a surface resistance of 10 ⁹ to 10 ¹⁴
It is desirable to have a low-resistance layer of Ω · cm from the viewpoint of realizing charge injection and preventing generation of ozone, but a photoreceptor other than the above may be used.

3) As a developing method of the electrostatic latent image, in the embodiment, a one-component non-contact developing method (jumping developing)
However, other developing methods may be used.

4) A magnetic brush charger as a contact charging member is a magnet roller 22-fixed, a non-magnetic sleeve 21
Although a so-called sleeve rotation type charger of rotation was used, the invention is not limited to this configuration. For example,
A system in which the magnet roller 22 rotates with the same configuration, or a system in which the magnet roller itself rotates with only the magnet roller 22 can be used by performing a conductive treatment on the roller surface.

5) As the waveform of the primary charging alternating voltage component for the contact charging member, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate. For example, a DC power supply is periodically turned on,
Includes a rectangular wave voltage formed by turning off. The same applies to the AC bias when the AC bias component is included in the developing bias applied to the developing device.

6) The transfer method may be roller transfer, blade transfer, corona discharge transfer, or the like. The present invention can be applied not only to single-color image formation but also to an image forming apparatus for forming a multicolor, full-color image by multiple transfer or the like using an intermediate transfer member such as a transfer drum or a transfer belt.

7) The charging device and the electrophotographic apparatus of the present invention can be used not only for an electrophotographic laser printer but also for a copying machine,
It can be widely used in electrophotographic application fields such as CRT printers, LED printers, liquid crystal printers, and laser plate making. Further, the charging device of the present invention can be housed in a cartridge used in the copying machine or printer.

[0126]

As described above, according to the present invention,
Regarding the magnetic brush charging of the electrophotographic photosensitive member, the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member are determined. The configuration in which the width of charging by contacting the conductive magnetic powder to which a voltage is applied is short with respect to the longitudinal center in the rotation axis direction of the electrophotographic photosensitive member, more specifically,
Since the photosensitive layer and the charge injection layer of the photoreceptor in the photoreceptor rotational axis direction are coated so as to cover the outer end of the magnetic brush in the rotational axis direction with respect to the longitudinal center, the magnetic brush is The electric charge retention on the outside of the longitudinal end is increased, and the potential difference between the photosensitive member and the magnetic brush at the position corresponding to the outside of the end of the magnetic brush at the longitudinal end in the rotating magnetic direction of the photosensitive member is less likely to occur. Since the potential difference between the powder and the photoconductor is reduced, the magnetic powder extruded outward in the rotation axis direction at the charging nip portion is not electrically attached to the photoconductor. Therefore, it is possible to prevent the occurrence of charging failure and image failure and to repeatedly output a good image, and to provide a charging device that prevents the occurrence of image failure, an electrophotographic apparatus having the charging device, and a process cartridge. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to a first embodiment.

FIG. 2 is a model diagram of a photoconductor layer configuration.

FIG. 3 illustrates the principle of injection charging.

FIG. 4 is a model diagram of a magnetic powder adhesion preventing configuration.

FIG. 5 is a model diagram of a magnetic powder adhesion preventing configuration according to a second embodiment.

FIG. 6 is a schematic diagram of a configuration for preventing magnetic powder adhesion in Example 3.

FIG. 7 is a model diagram of a configuration for preventing magnetic powder adhesion in Example 4.

FIG. 8 is a model diagram showing the relationship between the coating width of the photosensitive layer and the charge injection layer and the end of the magnetic brush in Comparative Example 1.

FIG. 9 is a model diagram showing the relationship between the coating width of the photosensitive layer and the charge injection layer and the end of the magnetic brush in Comparative Example 2.

FIG. 10 is an explanatory diagram of magnetic brush charging.

[Explanation of symbols]

1. Electrophotographic photoreceptor, 11 Conductive support, 12
・ Photosensitive layer, 13 ・ ・ Charge injection layer, 2 ・ ・ Magnetic brush (magnetic brush charger), 21 ・ ・ Electrode sleeve, 22 ・ ・ Magnet roller, 23 ・ ・ Magnetic brush part, 24 ・ ・ Magnetic powder, n ..The charging nip, 3..the developing device, 4..the transfer roller, 5..the fixing device, 6 ... the cleaning device,
7. Laser beam scanner, L. Scanning exposure light, T
..Transfer parts, transfer materials

Claims (13)

[Claims] 1. A charging device for charging a rotatable electrophotographic photosensitive member by bringing a magnetic brush having conductive magnetic powder to which a voltage is applied into contact therewith, wherein said electrophotographic photosensitive member is a photosensitive layer and said photosensitive layer. An electrophotographic photosensitive member having a charge injection layer thereon, and a width for charging by contacting a conductive magnetic powder to which a voltage is applied is determined by the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member. A charging device, wherein the charging device is short with respect to a longitudinal center in a rotation axis direction of the photoconductor. 2. The charging device according to claim 1, wherein the charge injection layer of the electrophotographic photosensitive member contains conductive particles. 3. The charging device according to claim 1, wherein the magnetic brush is a rotatable brush roller. 4. The width of the rotating shaft of the electrophotographic photoreceptor, wherein the width of charging by contacting the conductive magnetic powder to which a voltage is applied is determined from the width of the photosensitive layer and the width of the charge injection layer in the direction of the rotating shaft of the electrophotographic photoreceptor. The charging device according to any one of claims 1 to 3, wherein the charging device is shorter than the center of the longitudinal direction by 3 mm or more. 5. An image forming apparatus for forming an image by applying an image forming process including a step of charging a rotatable electrophotographic photosensitive member by bringing a magnetic brush having conductive magnetic powder to which a voltage is applied into contact. In the photographic apparatus, the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and a voltage is applied based on the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the electrophotographic photosensitive member. An electrophotographic apparatus, wherein a width of charging by contacting a conductive magnetic powder is short with respect to a longitudinal center in a rotation axis direction of the electrophotographic photosensitive member. 6. The electrophotographic apparatus according to claim 5, wherein the charge injection layer of the electrophotographic photosensitive member contains conductive particles. 7. An electrophotographic apparatus according to claim 5, wherein said magnetic brush is a rotatable brush roller. 8. The rotation width of the electrophotographic photosensitive member is determined by the width of the photosensitive layer and the charge injection layer in the direction of the rotation axis of the electrophotographic photosensitive member. The electrophotographic apparatus according to any one of claims 5 to 7, wherein the length of the electrophotographic apparatus is shorter than the center in the direction by 3 mm or more. 9. An electrophotographic photoreceptor and a charging device for charging the electrophotographic photoreceptor by bringing a magnetic brush having a conductive magnetic powder to which a voltage is applied into contact with the electrophotographic photoreceptor are integrally supported. A process cartridge detachable from a photographic apparatus main body, wherein the electrophotographic photosensitive member has a photosensitive layer and a charge injection layer on the photosensitive layer, and a photosensitive layer width and charge injection in a rotation axis direction of the electrophotographic photosensitive member. A process cartridge, wherein a width of charging by contacting a conductive magnetic powder to which a voltage is applied is shorter than a layer width with respect to a longitudinal center in a rotation axis direction of the electrophotographic photosensitive member. 10. An electrophotographic photoreceptor, a charging device for charging the electrophotographic photoreceptor by bringing a magnetic brush having conductive magnetic powder to which a voltage is applied into contact with the electrophotographic photoreceptor, and a developing unit and a cleaning unit. A process cartridge that integrally supports one or both of them, and is detachable from an electrophotographic apparatus main body, wherein the electrophotographic photoreceptor has a photosensitive layer and a charge injection layer on the photosensitive layer; According to the width of the photosensitive layer and the width of the charge injection layer in the rotation axis direction of the photoconductor, the width of charging by contacting the conductive magnetic powder to which the voltage is applied is shorter than the center of the electrophotographic photoconductor in the rotation axis direction. Characteristic process cartridge. 11. The charge injection layer of the electrophotographic photosensitive member according to claim 9, wherein the charge injection layer contains conductive particles.
The process cartridge according to 1. 12. The process cartridge according to claim 9, wherein said magnetic brush is a rotatable brush roller. 13. The width of the rotating shaft of the electrophotographic photosensitive member, based on the width of the photosensitive layer and the width of the charge injection layer in the direction of the rotating shaft of the electrophotographic photosensitive member, which is charged by contacting a conductive magnetic powder to which a voltage is applied. 13. The process cartridge according to claim 9, wherein the length of the process cartridge is shorter than the center of the longitudinal direction by 3 mm or more.