JP2017058642A - Charging member, charging device, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging member that suppresses the generation of minute colored lines over time, the colored lines generated when an electrophotographic photoreceptor is charged with a contact charging system (DC contact charging system) where only a DC voltage is applied.SOLUTION: There is provided a charging member comprising a conductive substrate 30, a conductive elastic layer 31 arranged on the conductive substrate 30, and a conductive surface layer 32 arranged on the conductive elastic layer 31, where when surface height components of the conductive surface layer 32 are analyzed in terms of frequency by binarizing the average value of the surface height components as a threshold, the integrated value of the period within a range of 25 μm or more and 200 μm or less is 1600 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a charging member, a charging device, an image forming apparatus, and a process cartridge.

  In recent years, electrophotographic image formation has been widely used in image forming apparatuses such as copying machines and laser printers.

  In an image forming apparatus using an electrophotographic method, for example, the surface of an electrophotographic photosensitive member is first charged by a charging device, and after forming an electrostatic latent image with a laser beam or the like that modulates an image signal, the charged toner Thus, a toner image visualized by developing the electrostatic latent image on the surface of the electrophotographic photosensitive member is formed. Then, for example, a toner image is electrostatically transferred to a recording material such as recording paper via an intermediate transfer member or directly, and fixed on the recording material, whereby a reproduced image is obtained.

For example, Patent Document 1 states that “a surface roughness Rz that is provided on the substrate and contacts the member to be charged and has a surface roughness Rz of 2 μm or more and 20 μm or less, and (A) a resin and (B) A charging member comprising at least a conductive outermost layer containing conductive particles for forming the surface roughness, and charging the member to be charged by contacting the member to be charged in a state where a voltage is applied. Is disclosed.
Patent Document 2 states that “the shaft body, the conductive elastic layer formed on the outer periphery of the shaft body, and the resistance adjustment layer formed on the outer periphery of the conductive elastic layer, The layer is made of a cross-linked product of an extrusion-molded body made of a conductive rubber composition containing spherical particles having an average particle diameter of 2 to 5 μm. The surface roughness (Rz) of the resistance adjusting layer after cross-linking is 2 to 5 μm. The charging roll for an electrophotographic apparatus within the range of "."

JP 2010-231103 A JP 2010-072450 A

  An object of the present invention is to provide a conductive base material, a conductive elastic layer disposed on the conductive base material, and a surface height component of the conductive surface layer by using an average value of the surface height components as a threshold value. Compared to the case where the integrated value of the period in the range of 25 μm or more and 200 μm or less exceeds 1600, the charge charging method (hereinafter referred to as “DC contact charging method”) may be described. A charging member that suppresses the generation of minute color lines over time, which occurs when charging is performed.

  The above problem is solved by the following means.

The invention according to claim 1
A conductive substrate, a conductive elastic layer disposed on the conductive substrate, and a conductive surface layer disposed on the conductive elastic layer;
When the surface height component of the conductive surface layer is binarized by using the average value of the surface height component as a threshold value and frequency analysis, the charging member has an integrated value of a period in the range of 25 μm or more and 200 μm or less of 1600 or less .

The invention according to claim 2
The charging member according to claim 1, wherein an integral value of the period is 1100 or more.

The invention according to claim 3
The charging member according to claim 1, wherein an integral value of the period is 1200 or more and 1400 or less.

The invention according to claim 4
The charging member according to claim 1, wherein the conductive surface layer contains polyamide particles, carbon black, and dimethylpolysiloxane.

According to the invention of claim 5,
A charging device having the charging member according to claim 1.

The invention according to claim 6
An electrophotographic photoreceptor;
A charging device comprising the charging member according to any one of claims 1 to 4, and charging the surface of the electrophotographic photosensitive member by a contact charging method in which only a DC voltage is applied to the charging member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device that forms a toner image by developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner;
A transfer device for transferring the toner image to the surface of a recording medium;
An image forming apparatus comprising:

The invention according to claim 7 provides:
The image forming apparatus according to claim 6, wherein the total thickness of the surface layer having charge transportability of the electrophotographic photoreceptor is 20 μm or more and 50 μm or less.

The invention according to claim 8 provides:
The image forming apparatus according to claim 6, wherein the image forming apparatus does not have a static eliminating device that neutralizes residual charges on the surface of the electrophotographic photosensitive member.

The invention according to claim 9 is:
A charging device comprising the charging member according to any one of claims 1 to 4 and charging the surface of the electrophotographic photosensitive member by a contact charging method in which only a DC voltage is applied to the charging member.
A process cartridge that can be attached to and detached from an image forming apparatus.

According to the invention which concerns on Claim 1 or 4, it has an electroconductive base material, the electroconductive elastic layer arrange | positioned on an electroconductive base material, and the electroconductive surface layer arrange | positioned on an electroconductive elastic layer In the charging member, when the surface height component of the conductive surface layer is binarized with the average value of the surface height component as a threshold value and frequency analysis is performed, the integral value of the cycle in the range of 25 μm or more and 200 μm or less exceeds 1600. Compared to the case, there is provided a charging member that suppresses the generation of minute color lines over time, which occurs when charged by a DC contact charging method.
According to the invention which concerns on Claim 2, compared with the case where the integral value of the said period is less than 1100, the charging member which suppresses the rotation failure of a charging member is provided.
According to the invention of claim 3, the charging member that suppresses the generation of minute color lines over time, which occurs when charging by the DC contact charging method, as compared with the case where the integral value of the period is less than 1200 or exceeds 1400. Is provided.

  According to the invention which concerns on Claim 5, it has an electroconductive base material, the electroconductive elastic layer arrange | positioned on an electroconductive base material, and the electroconductive surface layer arrange | positioned on an electroconductive elastic layer, When the surface height component of the conductive surface layer is binarized using the average value of the surface height component as a threshold value and frequency analysis is performed, a charging member having a cycle integral value in the range of 25 μm or more and 200 μm or less exceeding 1600 is provided. Compared to the above, a charging device that suppresses generation of minute color lines with time is provided.

  According to the invention of claim 6, a DC contact charging type charging device includes a conductive base material, a conductive elastic layer disposed on the conductive base material, and a conductive material disposed on the conductive elastic layer. The integrated value of the period in the range of 25 μm or more and 200 μm or less when the surface height component of the conductive surface layer is binarized with the average value of the surface height component as a threshold value. Is provided with an image forming apparatus that suppresses the generation of minute color lines over time as compared to a case where the charging member has a charging member exceeding 1600.

  According to the invention of claim 7, a DC contact charging type charging device includes a conductive substrate, a conductive elastic layer disposed on the conductive substrate, and a conductive layer disposed on the conductive elastic layer. The integrated value of the period in the range of 25 μm or more and 200 μm or less when the surface height component of the conductive surface layer is binarized with the average value of the surface height component as a threshold value. Compared with the case where the charging member has a charge transporting property of more than 1600, an image that suppresses the generation of minute color lines over time even if the electrophotographic photosensitive member having a total thickness of the charge transporting surface layer of 20 μm to 50 μm A forming apparatus is provided.

  According to the eighth aspect of the present invention, a DC contact charging type charging device includes a conductive base material, a conductive elastic layer disposed on the conductive base material, and a conductive material disposed on the conductive elastic layer. The integrated value of the period in the range of 25 μm or more and 200 μm or less when the surface height component of the conductive surface layer is binarized with the average value of the surface height component as a threshold value. Is provided with an image forming apparatus that suppresses the generation of minute color lines over time even without a charge eliminating device that eliminates residual charges on the surface of the electrophotographic photosensitive member, compared with a case where the charging member has a charging member exceeding 1600. .

  According to the ninth aspect of the present invention, a DC contact charging type charging device includes a conductive base material, a conductive elastic layer disposed on the conductive base material, and a conductive material disposed on the conductive elastic layer. The integrated value of the period in the range of 25 μm or more and 200 μm or less when the surface height component of the conductive surface layer is binarized with the average value of the surface height component as a threshold value. Compared to a case where the charging member has more than 1600, a process cartridge that suppresses generation of minute color lines with time is provided.

It is the schematic which shows an example of a structure of the charging member which concerns on this embodiment. 1 is a schematic diagram illustrating an example of a basic configuration of an image forming apparatus according to an exemplary embodiment. It is the schematic which shows the other example of the basic composition of the image forming apparatus which concerns on this embodiment. It is a schematic diagram showing an example of a basic configuration of a process cartridge according to the present embodiment. It is a schematic diagram for demonstrating the presumed effect | action which suppresses generation | occurrence | production of the fine color line | wire over time. It is the schematic diagram which graphed the frequency component obtained when binarizing about the surface height component of an electroconductive surface layer, and binarizing by making the average value of the said surface height component into a threshold value. It is a schematic diagram for demonstrating the presumed effect | action which a minute color line generate | occur | produces with time.

  Hereinafter, embodiments will be described in detail. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted.

[Charging member]
The charging member according to the present embodiment includes a conductive substrate, a conductive elastic layer disposed on the conductive substrate, and a conductive surface layer disposed on the conductive elastic layer. When the surface height component of the conductive surface layer is binarized by using the average value of the surface height components as a threshold value and frequency analysis, the integrated value of the period in the range of 25 μm to 200 μm is 1600 or less.

  In the charging member according to the present embodiment, the above configuration suppresses the generation of minute color lines over time. The reason is presumed as follows.

In the current field of electrophotographic technology, a long-life and inexpensive apparatus is required. For example, a DC contact charging method (contact charging method in which only a direct current voltage is applied) is used. However, when a charging device of a DC contact charging method (contact charging method in which only a direct current voltage is applied) is employed, minute color lines may be generated over time as image defects.
The generation of minute color lines is caused by the frequency of the discharge phenomenon (post discharge) that occurs immediately after the contact portion between the electrophotographic photosensitive member (hereinafter also referred to as “photosensitive member”) and the charging member (hereinafter referred to as “discharge frequency”). It is thought to be caused. In the case of a charging method that applies only direct current, the frequency of discharge immediately after the contact portion between the photosensitive member and the charging member tends to decrease, and a region that is not sufficiently charged may appear irregularly, resulting in the appearance of minute color lines. .

  The generation of minute color lines is often further increased due to the influence of contaminating components contained in the developer and the like that adhere to the surface of the charging member, particularly when the charging member continues to be used in the image forming apparatus. This phenomenon is considered to be because the contamination state of the surface of the charging member changes greatly with time. Specifically, it is estimated as follows. First, in the initial stage of contamination, only the convex top portion of the surface of the charging member is contaminated, and there are few contaminated regions and many uncontaminated regions (see FIG. 7A). After that, as the contamination progresses, the contaminated area gradually increases, so that the contamination state of the surface of the charging member greatly changes with time (see FIG. 7B). This large change in the contamination state is considered to cause a decrease in “the frequency of discharge immediately after the contact portion between the photosensitive member and the charging member”, which causes generation of minute color lines.

  Therefore, when the surface height component of the conductive surface layer is binarized using the average value of the surface height component as a threshold value and frequency analysis, the integrated value of the period in the range of 25 μm to 200 μm is set to 1600 or less. This state indicates that the surface of the conductive surface layer has convex portions having a nearly uniform height at fine intervals. When the charging member having the conductive surface layer having such a surface roughness is contaminated only at the top of the convex portion at the initial stage of contamination, the charging member has a large number of already contaminated regions (FIG. 5A). )reference). Thereafter, even if contamination progresses, the contamination state on the surface of the charging member hardly changes over time (see FIG. 5B). For this reason, the decrease in “the discharge frequency immediately after the contact portion between the photosensitive member and the charging member” that causes the generation of minute color lines is less likely to occur over time, and the generation of minute color lines over time can be suppressed.

  From the above, it is presumed that the charging member according to the present embodiment suppresses the generation of minute color lines over time due to the above configuration.

  In the charging member according to the present embodiment, when the surface height component of the conductive surface layer is binarized using the average value of the surface height component as a threshold value and frequency analysis is performed, the integrated value of the period in the range of 25 μm to 200 μm (Hereinafter may be abbreviated as “integrated value of a specific period”) is 1600 or less, but is preferably 1200 or more and 1400 or less from the viewpoint of suppressing generation of minute color lines over time. On the other hand, the integral value of the specific period is preferably 1100 or more, and more preferably 1200 or more, from the viewpoint of suppressing the rotation failure (for example, driven rotation failure) of the charging member.

  The frequency analysis of the surface height component of the conductive surface layer and the calculation of the integration value of the specific period are described in [Example] [Measurement of the surface height component and frequency analysis, and the integration value of the specific period. The method described in the column “Calculation of” is performed.

In addition, as a method for controlling the integral value of the specific period within the above range, unevenness-providing particles (other particles other than conductive particles: for example, polyamide resin particles, polyimide resin particles, polyacrylic) blended in the conductive surface layer Resin particles such as acid resin particles, polymethacrylic resin particles, polystyrene resin particles, fluororesin particles, and silicone resin particles; carbon particles, metal particles, metal oxide particles obtained by sintering carbon black, graphite, phenol resin, etc. The method of adjusting the particle diameter, shape, and content of (inorganic particles).
Specifically, for example, the number average particle diameter of the unevenness imparting particles is 1.0 μm to 10.0 μm (preferably 2.0 μm to 6.0 μm), and the circularity is 0.60 to 0.99 (preferably Is 0.80 or more and 0.90 or less), and the content (content with respect to the conductive surface layer) is 5 mass% or more and 40 mass% or less (preferably 15 mass% or more and 25 mass% or less).

Here, the number average particle diameter (D50p) of the unevenness imparting particles (other particles other than the conductive particles) is a value measured by the following method.
First, a measurement sample is cut out from the conductive surface layer of the charging member. Then, the cross section of the measurement sample is observed with an SEM (Scanning Electron Microscope) and image analysis is performed. The longest diameter and the shortest diameter of the primary particles of the unevenness-imparting particles obtained by image analysis are measured, and the sphere equivalent diameter is measured from this intermediate value. The measurement of the equivalent sphere diameter is performed on 100 primary particles having irregularities. The 50% diameter (D50p) in the cumulative frequency on the basis of the number of sphere equivalent diameters of primary particles of the obtained unevenness imparting particles is determined as the number average particle size of the unevenness imparting particles.
The number average particle diameter of the unevenness-imparting particles may be obtained by collecting the unevenness-imparting particles and directly observing the particles.

Moreover, the circularity of the unevenness imparting particles is a value measured by the following method.
A measurement sample is cut out from the conductive surface layer of the charging member. Then, the cross section of the measurement sample is observed with an SEM (Scanning Electron Microscope) and image analysis is performed. The circularity of the primary particles of the unevenness imparting particles obtained by image analysis is calculated by an equation. The calculation of the degree of circularity is performed for 100 primary particles having irregularities.
Formula: Circularity (100 / SF2) = 4π × (A / I ² )
[In formula, I shows the perimeter length of the primary particle of the uneven | corrugated particle | grains on an image, and A represents the projection area of the primary particle of an uneven | corrugated particle | grain. SF2 represents a shape factor. ]
The irregularity-providing particles may be collected and directly observed to determine the circularity of the irregularity-providing particles.

  In addition, as a method of controlling the integral value of the specific period within the above range, a method of adjusting the amount of the additive (for example, dimethylpolysiloxane) of the conductive surface layer is also exemplified.

Hereinafter, the details of the charging member according to the present embodiment will be described.
FIG. 1 shows an example of the configuration of the charging member according to the present embodiment. The charging member shown in FIG. 1 includes a conductive base material 30 made of a cylindrical or columnar rod-shaped member (shaft), a conductive elastic layer 31 disposed on the outer peripheral surface of the shaft 30, and a conductive elastic layer 31. And a conductive surface layer 32 disposed on the outer peripheral surface of the charging roll 208. The shaft 30 and the conductive elastic layer 31 are bonded by, for example, an adhesive layer (not shown).

  The shape of the charging member according to the present embodiment is not particularly limited, and examples thereof include a roll shape, a brush shape, a belt (tube) shape, and a blade shape. Among these, a roll-shaped charging member described in the present embodiment is preferable, that is, a so-called charging roll is preferable. Hereinafter, as an example of the charging member according to the present embodiment, a roll-shaped charging member (hereinafter sometimes referred to as a charging roll) will be mainly described.

In this specification, the term “conductive” means that the volume resistivity at 20 ° C. is less than 1 × 10 Ωcm, and the term “semiconductive” means that the volume resistivity at 20 ° C. is 1 × 10 Ωcm or more and 1 × 10 ^10. It means that it is below Ωcm. Further, the volume resistivity in this specification is a value measured by a TREK volume resistance meter MODEL 152-1 or the like.

  Next, each component of the charging member according to the present embodiment will be described. In the following description, “conductive substrate” may be referred to as “substrate”, “conductive elastic layer” may be referred to as “elastic layer”, and “conductive surface layer” may be referred to as “surface layer”.

(Base material)
The base material 30 functions as an electrode and a supporting member of the charging roll. For example, the material is a metal or alloy such as iron (free cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel; chromium And iron plated with nickel or the like; conductive materials such as conductive resin.
The base material 30 is a conductive rod-like member, and examples thereof include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. .
The substrate 30 may be a hollow member (tubular member) or a non-hollow member.

(Elastic layer)
The elastic layer 31 is disposed in a roll shape on the outer peripheral surface of the conductive substrate (shaft) 30.
The elastic layer 31 includes, for example, an elastic material, a conductive agent, and other additives as necessary.

  Elastic materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide- Examples include allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blend rubbers thereof. Among these, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blended rubbers thereof are desirably used. These elastic materials may be foamed or non-foamed.

Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent.
Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide And various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution;
Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; alkaline earth metal perchlorates and chlorates; Can be mentioned.
A conductive agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The carbon black specifically includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, and “Special Black” manufactured by Orion Engineered Carbons. 4 ”,“ Special Black 4A ”,“ Special Black 550 ”,“ Special Black 6 ”,“ Color Black FW200 ”,“ Color Black FW2 ”,“ Color Black FW2V ”,“ MONARCH1000 ”manufactured by Cabot Corporation "MONARCH1300" manufactured by Cabot Corporation, "MONARCH1400" manufactured by Cabot Corporation, "MOGUL-L", "REGAL400R", and the like.

  The average particle size of the conductive agent is preferably 1 nm or more and 200 nm or less. In addition, an average particle diameter is made into an average particle diameter by observing a conductive agent with an electron microscope, measuring 100 diameters of a conductive agent, and taking the average.

The addition amount of the conductive agent in the elastic layer 31 is not particularly limited, but in the case of an electronic conductive agent, it is preferably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the elastic material, and 15 parts by mass. It is more desirable that the range be 25 parts by mass or less.
On the other hand, in the case of an ionic conductive agent, it is desirable that the amount be in the range of 0.1 parts by weight or more and 5.0 parts by weight or less, with respect to 100 parts by weight of the elastic material. It is more desirable to be in the range.

  Examples of other additives blended in the elastic layer 31 include a softener, a plasticizer, a curing agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, a coupling agent, and a filler (silica, Examples thereof include materials that can be added to a known elastic layer such as calcium carbonate).

  When the elastic layer 31 is formed, the mixing method and order of the conductive agent, elastic material, and other components (components such as a vulcanizing agent and a foaming agent added as necessary) constituting the elastic layer 31 are particularly Although not limited, a general method includes a method in which all components are mixed in advance with a tumbler or a V-blender, and are melt-mixed with an extruder and extruded.

The thickness of the elastic layer 31 is preferably about 1 mm to 10 mm, and more preferably about 2 mm to 5 mm.
Further, the volume resistivity of the elastic layer 31 is desirably 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less.

(Surface layer)
The surface layer 32 is a layer formed mainly for preventing contamination by toner or the like, and is formed by dispersing particles in a binder resin.

  Examples of the binder resin used for the surface layer 32 include polyamide resin, urethane resin, polyester resin, phenol resin, acrylic resin, epoxy resin, and cellulose. Among these, polyamide resin is preferable. Examples of the polyamide resin include polyamide resins described in the polyamide resin handbook, Osamu Fukumoto (Nikkan Kogyo Shimbun). Among these, in particular, the polyamide resin is preferably an alcohol-soluble polyamide from the viewpoint of suppressing the contamination of the conductive outermost layer 32 and facilitating the generation of fine color streaks, and an alkoxymethylated polyamide (alkoxymethylated nylon). Is more preferable, and methoxymethylated polyamide (methoxymethylated nylon) is still more preferable.

  The particles contained in the surface layer 32 are subjected to resistance control by using a conductive material, reduce environmental fluctuations in the resistance value of the surface layer 32, obtain stable charging characteristics, and control unevenness of the roll surface. Thus, it is used for the purpose of lowering the coefficient of friction with the photoreceptor and improving the abrasion resistance between the photoreceptors. In addition, an additive or the like can be used for the purpose of improving adhesion with the lower layer (for example, the elastic layer 31) or controlling the dispersion of particles in the binder resin.

The conductive particles are preferably those having a particle size of 3 μm or less and a volume resistivity of 10 ⁹ Ωcm or less. For example, particles made of metal oxides such as tin oxide, titanium oxide, zinc oxide, or alloys thereof, or carbon black can be used.
As other particles, fluorine-based or silicone-based, alumina, silica, and polyamide-based particles can be used, and those having a particle size of 3 μm to 10 μm are desirable.

  In particular, the conductive particles contained in the surface layer 32 affect the volume resistivity of the charging roll, and the type and content of the particles may be selected according to the target volume resistivity. Usually, conductive particles are blended in the range of 2 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the surface layer 32.

The surface layer 32 preferably contains carbon black and polyamide particles as particles and dimethylpolysiloxane as an additive from the viewpoint of suppressing generation of minute color lines.
Examples of the polyamide particles include polyamide resin particles described in the polyamide resin handbook, Osamu Fukumoto, 8400, (Nikkan Kogyo Shimbun). Among these, particularly as the polyamide resin, alcohol-soluble polyamide particles are preferable, alkoxymethylated polyamide particles (alkoxymethylated nylon particles) are more preferable, and methoxymethylated polyamide particles (methoxymethylated nylon particles) are still more preferable.

The surface layer 32 is formed by applying a coating liquid (surface layer forming coating liquid) containing the above binder resin and particles, and an additive added as necessary, onto the conductive elastic layer.
As a coating method of the surface layer forming coating solution, a usual method such as a roll coating method, a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, etc. Can be used.

  After applying the surface layer forming coating solution, the surface layer is formed by drying. Drying temperature is 80 degreeC or more and 200 degrees C or less, for example.

The thickness of the surface layer 32 is desirably about 5 μm to 20 μm, and more desirably about 7 μm to 13 μm.
Further, the volume resistivity of the surface layer is preferably 1 × 10 ³ Ωcm or more and 1 × 10 ¹⁴ Ωcm or less.

[Image forming apparatus (and process cartridge)]
The image forming apparatus according to this embodiment includes the electrophotographic photosensitive member and the charging member according to the present embodiment, and the surface of the electrophotographic photosensitive member is contacted by a contact charging method in which only a DC voltage is applied to the charging member. An electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member, and a developer formed on the surface of the electrophotographic photosensitive member by a developer containing toner. A developing device that develops the electrostatic latent image to form a toner image; and a transfer device that transfers the toner image to the surface of the recording medium.

  An image forming apparatus according to the present embodiment includes a fixing device that fixes a toner image transferred to the surface of a recording medium; direct transfer that directly transfers a toner image formed on the surface of an electrophotographic photosensitive member to a recording medium Type apparatus; intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred onto the surface of the intermediate transfer member, and the toner image transferred onto the surface of the intermediate transfer member is secondarily transferred onto the surface of the recording medium. System apparatus; an apparatus having a cleaning device for cleaning the surface of an electrophotographic photosensitive member after transfer of a toner image and before charging; an electrophotographic photosensitive member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature A known image forming apparatus such as an apparatus provided with a heating member is applied.

  In the case of an intermediate transfer type device, the transfer device includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. A configuration including an apparatus and a secondary transfer apparatus that secondary-transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium is applied.

  The image forming apparatus according to the present embodiment may be either a dry developing type image forming apparatus or a wet developing type (developing type using a liquid developer).

  Note that in the image forming apparatus according to the present embodiment, for example, the portion including the charging member according to the present embodiment may be a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including the charging member according to the present embodiment is preferably used. In addition to the charging member according to the present embodiment, the process cartridge may include at least one selected from the group consisting of an electrophotographic photosensitive member, an electrostatic latent image forming device, a developing device, and a transfer device, for example. Good.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

<First Embodiment>
FIG. 2 schematically shows the basic configuration of the image forming apparatus according to the first embodiment. An image forming apparatus 200 shown in FIG. 2 is connected to an electrophotographic photosensitive member 1, a power source 209, a DC contact charging type charging device that charges the electrophotographic photosensitive member 1, and an electrophotographic photosensitive member charged by the charging device. An exposure apparatus 210 (an example of an electrostatic latent image type apparatus) that exposes 1 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure apparatus 210 is developed with a developer containing toner. A developing device 211 for forming a toner image, a transfer device 212 for transferring the toner image formed on the surface of the electrophotographic photosensitive member 1 to the recording medium 500, and a toner remaining on the surface of the electrophotographic photosensitive member 1 after transfer. A toner removing device 213 for removing the toner image, and a fixing device 215 for fixing the toner image transferred to the recording medium 500 to the recording medium 500.

  Note that the image forming apparatus 200 shown in FIG. 2 does not include an erase-less type image that does not include a charge eliminating device that removes charges remaining on the surface of the electrophotographic photosensitive member 1 after the toner image on the surface of the electrophotographic photosensitive member 1 is transferred. Forming device. When a static eliminator that removes charges remaining on the surface of the electrophotographic photosensitive member 1 is not provided, minute color lines are likely to be generated in an image. This is because the surface of the electrophotographic photoreceptor 1 that has not undergone static elimination has a variation in charge, and it is considered that the discharge frequency immediately after the contact portion between the electrophotographic photoreceptor 1 and the charging roll 208 is likely to decrease. . However, since the image forming apparatus 200 (that is, the image forming apparatus according to the present embodiment) includes the charging member according to the present embodiment as the charging roll 208, generation of minute color lines is suppressed even without the charge eliminating device. Is done.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor 1 is not particularly limited, and a known electrophotographic photoreceptor can be used. For example, an undercoat layer, a charge generation layer, and a charge transport layer are laminated in this order on a conductive substrate, and a function-separated type photosensitive layer in which the charge generation layer and the charge transport layer are separately provided is provided. Examples include a photoreceptor. Further, it may be a function-integrated type photoreceptor having a photosensitive layer in which a charge generation layer and a charge transport layer are integrally formed.
Further, the photoreceptor 1 may not include an undercoat layer, an intermediate layer may be provided between the undercoat layer and the photosensitive layer, or a protective layer containing a charge transport material may be provided on the photosensitive layer. It may be provided.

  The electrophotographic photoreceptor 1 preferably has a total thickness of the surface layer having charge transportability of 20 μm or more and 50 μm or less, more preferably 24 μm or more and 50 μm or less, from the viewpoint of extending the life, and 28 μm. More preferably, it is 38 μm or less.

For example, in an image forming apparatus equipped with a DC contact charging device, when a function-separated type photoreceptor having a charge transport layer as the outermost surface layer is used, the longer the life of the charge transport layer, the longer the life can be achieved. , Minute color lines are likely to occur. The first charge transport layer and the second charge transport layer may also be provided on the first charge transport layer when the second charge transport layer that is less worn than the first charge transport layer is provided as a protective layer. The longer the total thickness of the (protective layer), the longer the life can be achieved, while the fine color lines are more likely to occur.
That is, in the case of a function-integrated type photoconductor as well, the longer the total thickness of the surface layer having charge transportability, the longer the life can be achieved, but fine color lines are more likely to occur. This is because the larger the total thickness of the surface layer having charge transportability, the lower the electrical responsiveness of the surface layer, and the frequency of discharge immediately after the contact portion between the electrophotographic photoreceptor 1 and the charging roll 208 tends to decrease. This is because it is considered to be.

  However, if the charging member according to this embodiment is used as the charging roll 208, even if the total thickness of the surface layer having charge transportability of the electrophotographic photosensitive member 1 is 20 μm or more and 50 μm or less, the generation of minute color lines is suppressed. In addition, the service life can be extended. In the present embodiment, the surface layer having charge transportability of the electrophotographic photoreceptor 1 is a charge transport layer and a protective layer when a protective layer containing a charge transport material is provided on the function-separated type photosensitive layer. When the protective layer containing the charge transport material is provided on the function-integrated type photosensitive layer, the total thickness of the photosensitive layer and the protective layer.

(Charging device)
The charging device is a DC contact charging type charging device that has the charging member according to the present embodiment as the charging roll 208 and charges the surface of the electrophotographic photosensitive member 1 by applying a DC voltage. Examples of the voltage to be applied include positive or negative DC voltage of 50 V or more and 2000 V or less, depending on the required photosensitive member charging potential.

  In addition, examples of the pressure at which the charging roll 208 contacts the electrophotographic photosensitive member 1 include a range of 250 mgf to 600 mgf.

  By bringing the charging roll 208 into contact with the surface of the photosensitive member 1, the charging device rotates following the photosensitive member 1 even when the charging device does not have a driving device. It may be rotated at a different peripheral speed.

(Exposure equipment)
As the exposure apparatus 210, a known exposure apparatus is used. Specifically, for example, an optical system device that performs exposure with a light source such as a semiconductor laser, an LED (Light Emitting Diode), or a liquid crystal shutter is used. The amount of time writing, for example, range from 0.5 mJ / ^{m 2} or more 5.0mJ / ^{m 2} and the like on the photosensitive member surface.

(Developer)
As the developing device 211, for example, a two-component developing type developing device that develops a developing brush (developer holding body) to which a developer composed of a carrier and a toner adheres is brought into contact with the electrophotographic photosensitive member 1, or conductive rubber elasticity. Examples thereof include a contact type one-component development type developing device that attaches toner onto a body conveyance roll (developer holding body) and develops the toner on an electrophotographic photosensitive member.
The toner is not particularly limited as long as it is a known toner. Specifically, for example, the toner may include at least a binder resin and, if necessary, a colorant, a release agent, and the like.

  The method for producing the toner is not particularly limited. For example, a known pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, emulsion polymerization aggregation method and the like are known. Examples thereof include a toner production method using a polymerization method.

  When the developer is a two-component developer composed of a toner and a carrier, the carrier is not particularly limited. For example, a core material such as a magnetic metal such as iron oxide, nickel or cobalt, or a magnetic oxide such as ferrite or magnetite. And a carrier coated with a resin layer on the surface of the core material (non-coated carrier). In the two-component developer, for example, the mixing ratio (mass ratio) of the toner and the carrier is in the range of toner: carrier = 1: 100 to 30: 100, and even in the range of 3: 100 to 20: 100. Good.

(Transfer device)
Examples of the transfer device 212 include a roll-type contact charging member, a contact transfer charger using a belt, a film, a rubber blade, or the like, or a scorotron transfer charger or a corotron transfer charger using corona discharge. Can be mentioned.

(Toner removal device)
The toner removing device 213 is for removing residual toner adhering to the surface of the electrophotographic photosensitive member 1 after the transfer process, and the electrophotographic photosensitive member 1 thus cleaned is repeatedly subjected to the above image forming process. Provided. As the toner removing device 213, a foreign matter removing member (cleaning blade), brush cleaning, roll cleaning, and the like are used. Among these, it is desirable to use a cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.
Note that the toner removing device 213 need not be provided when residual toner is not a problem, for example, when the toner hardly remains on the surface of the photoreceptor 1.

A basic image forming process of the image forming apparatus 200 will be described.
First, the charging device charges the surface of the photoreceptor 1 to a predetermined potential. Next, the surface of the charged photoreceptor 1 is exposed by the exposure device 210 based on the image signal to form an electrostatic latent image.
Next, the developer is held on the developer holding member of the developing device 211, the held developer is conveyed to the photosensitive member 1, and the developer holding member and the photosensitive member 1 are in proximity (or contact). It is supplied to the electrostatic latent image. As a result, the electrostatic latent image is visualized and becomes a toner image.
The developed toner image is conveyed to the position of the transfer device 212 and transferred directly to the recording medium 500 by the transfer device 212.
Next, the recording medium 500 to which the toner image is transferred is conveyed to the fixing device 215, and the toner image is fixed to the recording medium 500 by the fixing device 215. Examples of the fixing temperature include 100 ° C. or higher and 180 ° C. or lower.
On the other hand, after the toner image is transferred to the recording medium 500, the toner particles that are not transferred and remain on the photoreceptor 1 are conveyed to a contact position with the toner removing device 213 and are collected by the toner removing device 213.
As described above, image formation by the image forming apparatus 200 is performed. When the next image formation is performed, the next image formation process is performed without going through the step of removing the charge on the surface of the photoreceptor 1.

Second Embodiment
FIG. 3 schematically shows the basic configuration of the image forming apparatus according to the second embodiment. An image forming apparatus 220 shown in FIG. 3 is an intermediate transfer type image forming apparatus. In the housing 400, four electrophotographic photosensitive members 1a, 1b, 1c, and 1d are arranged in parallel along the intermediate transfer belt 409. ing. For example, an image is formed in which the photoreceptor 1a is yellow, the photoreceptor 1b is magenta, the photoreceptor 1c is cyan, and the photoreceptor 1d is black.
The image forming apparatus 220 shown in FIG. 3 is also an eraseless image forming apparatus that does not include a charge eliminating device that removes the charge remaining on the surface of the photoconductor after the toner image on the surface of the photoconductor is transferred.

  Each of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d rotates in one direction (counterclockwise on the paper surface), and charging rolls 402a, 402b, 402c, and 402d, and developing devices 404a, 404b, and 404c, 404d, primary transfer rolls 410a, 410b, 410c, 410d and cleaning blades 415a, 415b, 415c, 415d are arranged. Each of the charging rolls 402a, 402b, 402c, and 402d is a charging roll according to the above-described embodiment, and employs a contact charging method that applies only a DC voltage.

  The developing devices 404a, 404b, 404c, and 404d supply toners of four colors, black, yellow, magenta, and cyan, stored in toner cartridges 405a, 405b, 405c, and 405d, respectively, and primary transfer rolls 410a, 410b, 410c and 410d are in contact with the electrophotographic photoreceptors 1a, 1b, 1c and 1d through the intermediate transfer belt 409, respectively.

A laser light source (exposure device) 403 is disposed in the housing 400, and irradiates the surfaces of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d after charging with laser light emitted from the laser light source 403.
As a result, in the rotation process of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d, charging, exposure, development, primary transfer, and cleaning (removal of foreign matters such as toner) are sequentially performed, and the toner images of each color are intermediate The image is transferred onto the transfer belt 409 in an overlapping manner. The electrophotographic photoreceptors 1a, 1b, 1c, and 1d after the toner image is transferred onto the intermediate transfer belt 409 are subjected to the next image forming process without passing through the process of removing the surface charge.

  The intermediate transfer belt 409 is supported with tension by a drive roll 406, a back roll 408, and a support roll 407, and rotates without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to be in contact with the back roll 408 through the intermediate transfer belt 409. The intermediate transfer belt 409 that has passed through the position sandwiched between the back roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed facing the drive roll 406, and then forms the next image. Used repeatedly in the process.

  In addition, a container 411 for storing a recording medium is provided in the housing 400, and the recording medium 500 such as paper in the container 411 is sandwiched between the intermediate transfer belt 409 and the secondary transfer roll 413 by the transfer roll 412. After being sequentially transferred to a position, and further to a position sandwiched between two fixing rolls 414 that are in contact with each other, the sheet is discharged to the outside of the housing 400.

  In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. Good. In the case of a belt shape, a known resin is used as the resin material constituting the base material of the intermediate transfer member. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyether ether ketone and polyamide, and resin materials using these as main raw materials. Further, a resin material and an elastic material may be blended and used.

  The recording medium according to the above embodiment is not particularly limited as long as it is a medium that transfers a toner image formed on an electrophotographic photosensitive member.

<Process cartridge>
The process cartridge according to the present embodiment includes the charging member according to the present embodiment, and charges the surface of the electrophotographic photosensitive member by a contact charging method (DC contact charging method) in which only a DC voltage is applied to the charging member. And is configured to be attached to and detached from the image forming apparatus.
FIG. 4 schematically shows a basic configuration of an example of the process cartridge according to the present embodiment. In addition to the electrophotographic photosensitive member 1 and a DC contact charging type charging device that charges the surface of the electrophotographic photosensitive member 1 by applying a DC voltage to the charging roll, the process cartridge 300 is exposed to the electrophotographic photosensitive member 1 by exposure. A developing device 211 for developing the electrostatic latent image formed thereon with a developer containing toner to form a toner image; a toner removing device 213 for removing toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer; In addition, an opening 218 for exposure is combined and integrated using a mounting rail 216.

The process cartridge 300 includes a transfer device 212 that transfers the toner image formed on the surface of the electrophotographic photosensitive member 1 to the recording medium 500, and a fixing that fixes the toner image transferred to the recording medium 500 to the recording medium 500. The apparatus 215 is detachable from the main body of the image forming apparatus including other components (not shown), and constitutes the image forming apparatus together with the main body of the image forming apparatus.
The process cartridge 300 of the present embodiment exposes the surface of the electrophotographic photosensitive member 1 in addition to the electrophotographic photosensitive member 1, the charging device, the developing device 211, the toner removing device 213, and the opening 218 for exposure. An apparatus (not shown) may be provided.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Preparation of polyamide resin particles PA1 to PA2>
Polyamide resin particles (nylon 12 particles) were obtained by the following operation.
About 30 minutes until nylon 12 is completely dissolved at 190 ° C. in a mixing vessel equipped with a stirrer in which propylene glycol is mixed with 5% by mass of a nylon 12 pellet-like resin with carbon dioxide. Stir. The resulting solution was cooled at a rate of 5 ° C./min. In this cooling process, about 80% of the whole was granulated as monospherical nylon 12, but the remaining about 20% was precipitated as a lump. Bulky precipitates in this mixture were removed, the solvent was roughly separated by centrifugation, and dried to obtain nylon 12 particles. When the obtained nylon 12 particles were observed with a microscope, most of the particles were 10 μm or less, and other spherical particles in the range of 30 μm to 40 μm were confirmed. Moreover, as a result of confirming the particle size and distribution of the obtained nylon 12 particles with a particle size distribution measuring instrument, the number average particle size of the nylon 12 particles was 20 μm. Further, the obtained nylon 12 particles were treated with a ball mill for 30 minutes to obtain nylon 12 particles having a number average particle diameter of 10 μm. Next, the obtained nylon 12 particles (polyamide resin particles) were classified to obtain a particle size. A plurality of nylon 12 particle classified products having different circularity were obtained. Then, a plurality of nylon 12 particle classified products were combined and blended to obtain polyamide resin particles PA1 to PA2. Table 1 shows the number average particle diameter (D50p) and circularity of each polyamide resin particle.

<Example 1>
[Preparation of charging roll]
-Formation of conductive elastic layer-
Epichlorohydrin rubber (3106, manufactured by Nippon Zeon Co., Ltd.): 100 parts by mass Carbon black (Asahi # 60, manufactured by Asahi Carbon Co., Ltd.): 6 parts by mass Calcium carbonate (Whiteon SB, manufactured by Shiraishi Calcium Co.): 20 parts by mass Parts / ionic conductive agent (BTEAC, manufactured by Lion): 5 parts by massVulcanization accelerator: stearic acid (manufactured by NOF Corporation): 1 part by mass, vulcanizing agent: sulfur (Palnock R, manufactured by Ouchi Shinsei Chemical Co., Ltd.) ): 1 part by mass / Vulcanization accelerator: Zinc oxide: 1.5 parts by mass A conductive base material (metal shaft) having a diameter of 8 mm formed by SUS303 by kneading the mixture having the composition shown above with an open roll. A roll having a diameter of 15 mm was formed on the surface using a press molding machine through an adhesive layer, and then a conductive elastic roll having a diameter of 14 mm was obtained by polishing.

-Formation of conductive surface layer-
Binder resin: N-methoxymethylated nylon 1 (trade name F30K, manufactured by Nagase ChemteX Corporation) 100 parts by mass Particle A: Carbon black (trade name: MONAHRCH1000, manufactured by Cabot Corporation) 15 parts by mass Particle B: Polyamide Particle PA1 20 parts by mass Additive: Dimethylpolysiloxane (BYK-307, manufactured by Altana Co.) 1 part by mass A mixture of the above composition was diluted with methanol and dispersed in a bead mill. After dip-coating on the surface of the roll, it was dried by heating at 130 ° C. for 30 minutes to form a conductive surface layer having a thickness of 7 μm. Thus, the charging member (charging roll 1) of Example 1 was obtained.

<Example 2>
In the formation of the conductive surface layer, a charging roll of Example 2 was obtained in the same manner as in Example 1 except that the particles B were changed to polyamide particles PA2.

<Example 3>
In the formation of the conductive surface layer, a charging roll of Example 3 was obtained in the same manner as in Example 1 except that the additive was changed to 0 part by mass.

<Example 4>
In the formation of the conductive surface layer, a charging roll of Example 3 was obtained in the same manner as in Example 1 except that the polyamide particle PA1 was changed to 30 parts by mass.

<Example 5>
In the formation of the conductive surface layer, a charging roll of Comparative Example 1 was obtained in the same manner as in Example 1 except that the particle B was changed to 30 parts by mass of polyamide particle PB (polyamide 12, manufactured by Arkema).
<Comparative Example 1>
In the formation of the conductive surface layer, a charging roll of Comparative Example 1 was obtained in the same manner as in Example 1 except that the particle B was changed to 10 parts by mass of the polyamide particle PB (polyamide 12, manufactured by Arkema).
<Comparative example 2>
In the formation of the conductive elastic layer, the charging roll of Comparative Example 2 was obtained in the same manner as in Example 1 except that the molding method was extrusion molding to obtain a conductive elastic roll having a diameter of 14 mm.

<Measurement / Evaluation>
The following various measurements and evaluations were performed on the charging rolls obtained in the above examples and comparative examples. The results are shown in Tables 1 and 2.

[Measurement of surface height component and frequency analysis, and calculation of integral value of specific period]
-Measurement method-
The height component of the charging roll (conductive surface layer) was measured as follows. Using a laser microscope VK-8500 (manufactured by Keyence), measure the charging roll (conductive surface layer) with a 20x objective lens with a Dispense of 50 μm and a Pitch of 0.05 μm, and correct the curved surface to a median 3 × 3 image. The correction process was performed once. Thereby, the height component of the charging roll (conductive surface layer) was measured.
And the frequency analysis of the obtained surface height component was implemented as follows. Information on the obtained surface height component was digitized, and binarization processing was performed using the average value of the surface height component as a threshold value. The two-dimensional information subjected to the binarization process was subjected to a two-dimensional Fourier transform to calculate a frequency component. Based on this frequency component, integration was performed in the range of 25 μm or more and 200 μm or less of the cycle (reciprocal of frequency), and an integrated value (integration value of 25 to 200 μm cycle) of the range of 25 μm or more and 200 μm or less was calculated.

[Evaluation of minute color lines]
Equipped with a photoconductor with a total thickness of 28 μm of the surface layer having charge transporting property of the image forming apparatus “DocuCentre 505a (manufactured by Fuji Xerox)” having a contact charging device in which only a DC voltage is applied to the charging device In addition, the charging roll obtained in the above-described Examples and Comparative Examples was incorporated into an erase-less modified machine that does not include a static eliminator. Using this modified machine, 5000 full-tone images with an image density of 30% are output on A4 paper under high temperature and high humidity conditions, and then an entire halftone image with an image density of 30% is printed on an A4 paper. Output. The number of minute color lines generated in an area of 94 mm length and 200 mm width from the upper left of the output image was evaluated according to the following evaluation criteria. Here, the high temperature and high humidity is a surrounding environment of 28 ° C. and 85 RH%.
The evaluation of this minute color line was “Evaluation 1”. In Evaluation 1, except that the total thickness of the surface layer having charge transportability in the photoconductor mounted on the modified machine was changed to 16 μm, which is thin, Evaluation 2 was carried out in the same manner.
In Evaluation 1, Evaluation 3 was performed in the same manner as Evaluation 1 except that the static eliminator was mounted on the modified machine.
In addition, other failures (such as defective rotation of the charging roll) were also evaluated.

-Evaluation criteria for minute color lines-
G0: No generation of minute color lines G1: Generation of minute color lines of 1 to 3 points G2: Generation of minute color lines of 4 to 10 points G3: Generation of minute color lines of 11 to 20 points G4: 21 points Generation of fine color lines

  The details and evaluation results of each example and comparative example are listed in Tables 1 and 2 below.

From the above results, it can be seen that in the charging roll of this example, generation of minute color lines over time is suppressed as compared with the charging roll of the comparative example. However, in the charging roll of Example 5 in which the integrated value of the period in the range of 25 μm or more and 200 μm or less was too low, a driven rotation failure occurred.
Further, from the comparison between the evaluation 1 of the fine color line when the total thickness of the surface layer having the charge transporting property on the photoconductor mounted on the remodeling machine is 28 μm and the evaluation 2 of the fine color line when the thickness is as thin as 16 μm. In the case of evaluation 1 of the fine color line, the fine color line is more likely to be generated (see the comparative example), and it can be seen that this fine color line is suppressed in this example.
Furthermore, from the comparison of the micro color line evaluation 1 when the static eliminator is not mounted on the modified machine and the micro color line evaluation 3 when mounted, the micro color line evaluation 1 is the micro color line. It is easy to occur (see the comparative example), and it can be seen that this minute color line is suppressed in this embodiment.

1, 1a, 1b, 1c, 1d Electrophotographic photoreceptor, 30 conductive substrate, 31 conductive elastic layer, 32 conductive surface layer, 200 image forming apparatus, 208 charging roll, 210 exposure apparatus, 211 developing apparatus, 212 Transfer device, 213 Toner removal device, 215 fixing device, 220 Image forming device, 300 Process cartridge, 402a, 402b, 402c, 402d Charging roll, 404a, 404b, 404c, 404d Developing device, 500 Recording medium

Claims (9)

A conductive substrate, a conductive elastic layer disposed on the conductive substrate, and a conductive surface layer disposed on the conductive elastic layer;
When the surface height component of the conductive surface layer is binarized by using the average value of the surface height component as a threshold value and frequency analysis, the charging member has an integrated value of a period in the range of 25 μm or more and 200 μm or less of 1600 or less .   The charging member according to claim 1, wherein an integral value of the period is 1100 or more.   The charging member according to claim 1, wherein an integral value of the period is 1200 or more and 1400 or less.   The charging member according to claim 1, wherein the conductive surface layer contains polyamide particles, carbon black, and dimethylpolysiloxane.   A charging device having the charging member according to claim 1. An electrophotographic photoreceptor;
A charging device comprising the charging member according to any one of claims 1 to 4, and charging the surface of the electrophotographic photosensitive member by a contact charging method in which only a DC voltage is applied to the charging member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device that forms a toner image by developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner;
A transfer device for transferring the toner image to the surface of a recording medium;
An image forming apparatus comprising:   The image forming apparatus according to claim 6, wherein the total thickness of the surface layer having charge transportability of the electrophotographic photoreceptor is 20 μm or more and 50 μm or less.   The image forming apparatus according to claim 6, wherein the image forming apparatus does not have a static eliminating device that neutralizes residual charges on the surface of the electrophotographic photosensitive member. A charging device comprising the charging member according to any one of claims 1 to 4 and charging the surface of the electrophotographic photosensitive member by a contact charging method in which only a DC voltage is applied to the charging member.
A process cartridge that can be attached to and detached from an image forming apparatus.