JP2006154581A - Electrifying device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the fluctuation in a gap between a photoreceptor and a charging roller even when the external diameter of the electrifying roller is fluctuated by swelling and to prevent an abnormal image from being produced due to the occurrence of a flaw in the photoreceptor by contact of the photoreceptor and an electrifying portion of the charging roller and the consequent appearance of the trace of the flaw on the image, and to prevent the occurrence of the abnormal image of the charging defect of a non-contact portion caused by the flow of a current from the contact portion. <P>SOLUTION: The external diameter at both ends of a resistance layer is reduced by machining or polishing and annular rollers are inserted into the recessed portions. The annular rollers are preferably fixed by adhesives to the resistance layer. By employing such configuration, the resistance layer in the stepped portions of the spacer part are bulged by swelling even when the resistance layer swells and since the inserted roller swells integrally therewith, the gap is consequently maintained at nearly the same size as that before the swelling. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus used for a copying machine, a facsimile, a printer, and the like, and more particularly to an image carrier and a non-contact charging device.

In recent years, the contact charging method, which generates less discharge generation materials and can achieve lower power than the corona charging method, is becoming the mainstream of the charging method. However, since the charging member comes into contact with the member to be charged, the foreign matter adhering to the surface of the member to be charged easily attaches to the charging member via the contact position. Examples of the substance that transfers and adheres to the charging member include residual toner after transfer and paper powder that adheres to the surface of the photoreceptor. When these foreign substances transfer and adhere to the charging member, it may be difficult to maintain the initial function of the charging member, and the charging performance may be deteriorated.
In addition, when the driving of the apparatus is stopped while the charging member is in contact with the member to be charged, a material such as a plasticizer contained in the elastic layer of the charging member oozes out to the surface of the member to be charged. In some cases, the surface could be contaminated.

Therefore, in order to prevent the charging performance from being deteriorated due to foreign matter adhering to the charging member and contamination of the surface of the object to be charged by the material exuding from the charging member, a small gap is provided between the charging member and the object to be charged. A non-contact charging method has been proposed (see Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). These non-contact charging methods can suppress the generation of discharge generation materials, and the charging member and the member to be charged are opposed to each other with a minute gap, so that foreign substances are not easily transferred and attached to the charging member. Therefore, it is possible to maintain the charging performance. Further, since the charging member is separated from the member to be charged when the driving of the apparatus is stopped, it is possible to avoid contamination of the surface of the member to be charged with a substance that exudes from the charging member.

Thus, although it is a highly useful non-contact charging method, its market performance is few at present. One of the causes is that the gap between the charging member and the member to be charged has to be formed with a minute and high accuracy, and it is difficult to maintain the gap. According to Patent Document 3, the size of the minute gap is preferably 300 μm or less, more preferably 100 μm or less, and further preferably 80 μm or less. As one method for forming such a minute gap, in Patent Document 3, a “ring-shaped” gap holding member formed with a larger diameter than the charged elastic layer by the size of the gap is used as a roller-shaped charging member. It has been proposed to use a so-called butting roller system in parallel with the body elastic layer. However, with this method, the precision of the minute gap is the sum of the tolerance of the elastic layer thickness, the tolerance of the inner diameter of the ring-shaped gap holding member, and the tolerance of the outer diameter. Is difficult to hold.

In addition, as another method for forming a minute gap, Patent Documents 3 and 4 propose a method in which a film-like tape is attached to a charged body elastic layer. This method improves the gap accuracy inaccuracy of a plurality of tolerances as described above, but has a drawback of being vulnerable to external factors. For example, inadvertently hooking and peeling off the end of the tape, oil, moisture, dust, toner, etc. may enter the sticking surface from the end of the tape, and the gap cannot be stably maintained, It may be easy to peel off. For this reason, it is still difficult to maintain the gap.

In Patent Document 5, a proposal for maintaining a minute gap between a charging member and a member to be charged is made. One is a method in which a gap holding member made of a shrink material is placed around the base, and then contracted, and the gap holding member is brought into close contact with the outer peripheral surface of the base by the contraction force. The other is a structure in which a gap holding member made of a shrinkable material is placed around a resistance layer provided on the outer periphery of the substrate, and this is shrunk so as to be in close contact with the resistance layer.
These proposals make it possible to strongly attach the gap holding member to the base body or the charging member by contraction force. And according to this proposal, it prevents over a long period that the gap holding member which may be produced in the structure of the said patent document 3 and the patent document 4 peels off from charging member main bodies, such as a base | substrate and a resistance layer. be able to. Therefore, the gap between the charging member and the member to be charged can be stably held.

  Patent Document 6 proposes a means for achieving the gap between the charging member and the member to be charged more stably than the proposal of Patent Document 5 and achieving it more inexpensively and easily. However, in any of the above configurations, the following problem that the resin portion, which is the charging portion of the charging roller, swells in a high temperature and high humidity environment and the gap becomes narrow cannot be effectively prevented.

Our non-contact resin charging roller (H-NCR), a unique technology of our company (Ricoh), will swell when stored in a high-temperature and high-humidity environment. Due to the difference, the gap between the photoconductor and the charging roller is narrowed, and in the worst case, contact may occur.
When the photosensitive member and the charging portion of the charging roller come into contact with each other, a scratch is generated on the photosensitive member, and the scar appears on the image to become an abnormal image. Further, the contact causes a current to flow from the contact portion even if the photoconductor is not damaged, so that a current shortage in the non-contact portion occurs, and an abnormal image with poor charging occurs.
In particular, in an image forming apparatus in which Mars is applied to a photoconductor, if the gap is small, the charging roller may become dirty, and thus there is a high demand for gap accuracy between the charging roller and the member to be charged.

JP 58-76851 A Japanese Patent Laid-Open No. 2-148059 JP-A-4-360167 JP 2001-194868 A JP 2003-207996 A JP 2004-219444 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide an image forming apparatus that suppresses gap fluctuation between a photosensitive member and a charging roller and does not generate an abnormal image even when the outer diameter of the charging roller varies due to swelling. To do.

As means for solving the above problems, the present invention has the following features.
The charging device according to claim 1, wherein the charging device includes a charging member disposed so as to face the charged body, and applies a voltage to the charging member to charge the charged body. The charging member includes: A substrate, a resistance layer on an outer periphery of the substrate, and a spacer portion that contacts the member to be charged; the spacer portion contacts the member to be charged, so that at least a part of the resistor layer is in contact with the surface of the member to be charged. In the charging device configured to form the gap, the spacer portion is installed in a recess having a reduced outer shape at both ends of the resistance layer.
In the charging device according to a second aspect of the present invention, the spacer portion is configured by inserting a ring-shaped roller into the concave portion.
The charging device according to a third aspect is further characterized in that the concave portion is formed by cutting or polishing the resistance layer.
According to a fourth aspect of the present invention, the ring-shaped roller inserted into the recess is fixed to the resistance layer with an adhesive.

In the charging device according to claim 5, the material of the ring-shaped roller is a high-density polyethylene resin.
The charging device according to claim 6 is characterized in that the resistance layer is formed of a resin composition containing carbon and a polymer ion conductive material.
The charging device according to claim 7 is characterized in that the resin is a thermoplastic resin.
The charging device according to claim 8 is characterized in that the ion conductive material is a polymer compound containing a polyether ester amide component.

The charging device according to claim 9 is the charging device according to any one of claims 1 to 8, wherein the outer diameter of the recess is in the range of "87 to 97"% with respect to the outer diameter of the resistance layer. It is characterized by that.
The charging device according to claim 10 is characterized in that the predetermined gap between the resistance layer and the surface of the member to be charged is in the range of 10 to 50 μm.
In the charging device according to claim 11, the thickness of the ring-shaped roller is in a range of 2 to 6% with respect to the outer shape of the resistance layer.
13. The process cartridge according to claim 12, wherein the image carrier and at least one of a charging device, a developing device, and a cleaning device are integrally configured to be detachable from the image forming apparatus main body. The process cartridge includes the charging device according to any one of claims 1 to 11.
An image forming apparatus according to a thirteenth aspect includes the process cartridge according to the twelfth aspect.
An image forming apparatus according to a fourteenth aspect includes the charging device according to any one of the first to eleventh aspects.

As described above, according to the means for solving the above problem, the charging device of the present invention can suppress the gap fluctuation between the charging roller and the photoconductor even in a high-temperature and high-humidity environment, and an abnormal image is generated due to a charging failure. Can provide images without.

FIG. 1 is an axial sectional view of a charging roller according to the present embodiment.
In the present invention, when a roller attached to a conventional rotating shaft is provided with a recess in the resistance layer and directly inserted into the recess, the roller expands at the same time when the resistance layer swells and the outer diameter changes. As a result, the gap between the photosensitive member and the charging roller is maintained.

The charging device according to the present invention is characterized in that the spacer portion is installed in a recess having a reduced outer diameter at both ends of the resistance layer. When the resistance layer swells as described above with the conventional configuration (see FIG. 6), the spacer portion does not swell and has the same dimensions, and as a result, the gap decreases, and as a result, the resistance layer and the charged body It was a situation where the surface contacted.
In order to solve this problem, in the present invention, the spacer portion is configured as follows to prevent the gap from being reduced when the resistance layer swells. That is, as shown in FIG. 1, the outer diameter of both ends of the resistance layer is reduced by cutting or polishing, and a ring-shaped roller is inserted into the recessed portion. This ring-shaped roller is preferably fixed to the resistance layer with an adhesive.
With such a configuration, even when the resistance layer swells, the resistance layer in the portion of the spacer portion also swells and expands, and at the same time, the inserted roller also expands integrally. Therefore, as a result, the gap is maintained at almost the same size as before the swelling.

As a material of the roller of the present invention, a high density polyethylene resin is preferable. This is because it is important to select a material that is resistant to wear because it is in contact with the photoconductor in a pressurized state and high durability is required. In this example, Novatec PP-HY540 (manufactured by Nippon Polychem) was used.
Next, the material of the charging unit will be described.
The electric resistance adjusting layer is formed of a thermoplastic resin composition containing carbon and a polymer type ion conductive material. As the polymer ion conductive material, a polymer compound containing a polyether ester amide component is used. Polyether ester amide is an ion conductive polymer material, and is characterized in that it does not easily leak to the photoreceptor and bleed out to the surface.

The volume resistivity of the electrical resistance adjusting layer is preferably 10 ⁶ to 10 ⁹ Ωcm. If it exceeds 10 ⁹ Ωcm, a sufficient charge potential for obtaining a uniform image cannot be obtained due to insufficient charge amount. When it is lower than 10 ⁶ Ωcm, voltage concentration (leakage) and abnormal discharge occur on the photosensitive member defect portion.
For this purpose, it may be blended with an insulating thermoplastic resin at a predetermined ratio. The thermoplastic resin is not particularly limited, and examples thereof include general-purpose resins such as polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and copolymers thereof, and engineering plastics such as polycarbonate and polyacetal. Regarding the blending amount, the thickness of the electric resistance adjusting layer capable of obtaining a desired volume resistivity by setting the polymer type ion conductive material to 30 to 100% by weight with respect to 0 to 70% by weight of the thermoplastic resin is as follows. If it is too thin, abnormal discharge due to leakage occurs, and if it is too thick, it is difficult to maintain surface accuracy. Preferably they are 100 micrometers or more and 500 micrometers or less.

There is no restriction | limiting in particular in the manufacturing method of a thermoplastic resin composition, It can manufacture easily by melt-kneading the mixture of each material with a biaxial kneader, a kneader, etc. The step of forming the electrical resistance adjusting layer on the peripheral surface portion of the conductive support can be easily performed by covering the conductive support with the thermoplastic resin composition by means of extrusion molding or injection molding. .
If only the resistance adjusting layer is formed on the conductive support to constitute the conductive member, toner or the like may adhere to the resistance adjusting layer and the performance may be deteriorated. Such a problem can be eliminated by forming a surface layer on the resistance adjustment layer.

The resistance value of the surface layer is formed so as to be larger than that of the resistance adjusting layer, thereby avoiding voltage concentration and abnormal discharge (leakage) to the defective portion of the photoreceptor. However, if the resistance value of the surface layer is too high, the charging ability and the transfer ability will be insufficient. Therefore, the difference in resistance value between the surface layer and the resistance adjusting layer is preferably 10 ³ Ωcm or less.
As the material for forming the surface layer, a thermoplastic resin composition is preferable in that the film-forming property is good. As the resin material, fluorine resin, silicone resin, polyamide resin, polyester resin and the like are excellent in non-adhesiveness, and are preferable in terms of preventing toner sticking. Since the resin material is electrically insulating, the resistance of the surface layer is adjusted by dispersing various conductive materials in the resin.
The surface layer is formed on the resistance adjusting layer by dispersing the surface layer constituting material in an organic solvent to prepare a coating material, and coating it by spray coating, dipping or the like. About a film thickness, about 10-30 micrometers is desirable.

In FIG. 1, the outer diameter A is the outer diameter of the charging roller resistance layer, and the outer diameter B is the outer diameter of the charging roller recess.
FIG. 2 is a graph of experimental results showing the relationship between the thickness of the roller and the gap after being left in a high temperature and high humidity environment for 80 hours. From this result, the thickness of the roller is preferably 0.2 mm to 0.6 mm, and the outer diameter A is 11.17 mm. Therefore, B / A is in the following range.
That is, when B / A is calculated by the following method from the dimensions of each part in the embodiment in FIG.
1) When the difference between the outer diameter A and the outer diameter B is the largest Roller thickness max 0.7mm
Photoconductor gap min 0.01mm
Outer diameter A 11.17mm
Outer diameter B 9.79mm
{B = 11.17- (0.7-0.01) × 2 = 9.79}
Outer diameter ratio = B / A = 0.876 = 87.6%
2) When difference between outer diameter A and outer diameter B is minimum, roller thickness min 0.2mm
Photoconductor gap max 0.05mm
Outer diameter A 11.17mm
Outer diameter B 10.87mm
{B = 11.17- (0.2-0.05) × 2 = 10.87}
Outer diameter ratio = B / A = 0.973 = 97.3%
Therefore, the range of the outer diameter ratio is 87 to 97%.

In the present invention, as described above, the outer diameter (B / A) of the concave portion with respect to the outer diameter of the resistance layer is in the range of 87 to 97%. If it is less than 87%, the difference in expansion dimension due to swelling between the resistance layer portion and the roller outer diameter of the spacer portion becomes large, and a sufficient gap cannot be maintained. This is because the expansion force due to the swelling of the spacer portion becomes weak, whereas the thickness of the roller increases, so that the roller becomes difficult to expand.
On the contrary, if the outer diameter of the concave portion is larger than 97%, the thickness of the roller becomes small and the strength becomes insufficient, and the manufacture of the roller itself becomes difficult.

  In the present invention, the predetermined gap between the resistance layer and the surface of the member to be charged is in the range of 10 to 50 μm. If the gap is 10 μm or less, the gap holding effect of the present invention is not sufficiently obtained due to adhesion of foreign matters, and if the gap is 50 μm or more, the roller thickness is large and the roller is difficult to expand, so it is difficult to hold the gap. It is because it becomes.

In the present invention, the thickness of the roller is in the range of 2 to 6% with respect to the outer diameter of the resistance layer.
In FIG. 1, the value calculated from the ratio of the outer diameter A = 11.17 when the roller thickness is 0.2 to 0.6 mm is used as a reference. If it is 2% or less, problems such as insufficient strength of the rollers and difficulty in production occur. On the contrary, if it is 6% or more, the strength of the roller becomes so large that it is difficult to expand and the gap cannot be maintained.

Hereinafter, an embodiment in which the charging device of the present invention is applied to an image forming apparatus will be described.
FIG. 3 is a schematic configuration diagram showing the image forming apparatus. In FIG. 3, an image forming apparatus includes a photosensitive drum 1 as an image carrier, a charging device 2, a developing device 3 as a developing unit, a cleaning device 4 for cleaning the photosensitive drum 1, and electrostatic on the photosensitive drum 1. An image forming unit 100 including an optical writing unit 6 for writing a latent image is provided.

As the optical writing unit 6, for example, an optical signal corresponding to image information read by a scanner or the like is emitted from a semiconductor laser, and the laser beam is scanned by a polygon mirror that is rotationally driven. The optical signal 6a corresponding to the color-separated image information is written on the photosensitive drum 1 through a converging lens and a lens for correcting the tilting of the polygon mirror, a mirror for deflecting the laser beam, and the like. Can be used.

A paper feed unit 200 is provided below the image forming unit 100. The paper feed unit 200 includes a paper feed cassette 7 and a paper feed roller 9. The paper feed cassette 7 stores therein transfer paper 8 as a transfer material. The paper feed roller 9 is for separating and feeding the transfer paper 8 in the paper feed cassette 7 one by one. The transfer paper 8 fed by the paper feed roller 9 is temporarily kept in front of the photosensitive drum 1, and the leading edge of the image formed on the photosensitive drum 1 and the leading edge of the transfer paper 8 are the photosensitive member. The sheet is fed in synchronism with the rotation of the photosensitive drum 1 at a timing when the nip portion between the drum 1 and the transfer roller 10 reaches almost the same time. Further, a registration roller pair 11 is provided as a transfer material conveying means for refeeding the transfer paper 8.

Further, above the image forming unit 100, a fixing unit having a fixing roller 14 and a press roller 15 having a built-in heater rotatably disposed so as to be pressed against each other across the conveyance path T <b> 2 of the transfer paper 8. A fixing device 16 is provided. On the downstream side of the fixing device 16 in the conveyance direction of the transfer paper, the transfer paper 8 that has passed through the fixing nip between the fixing roller 14 and the press roller 15 is discharged on the upper portion of the main body case 100 a of the image forming unit 100. A paper discharge roller 18 for discharging to a stacker unit 17 as a tray is provided.

Further, a reading unit 300 is provided further above the image forming unit 100. The reading unit 300 includes a document illumination light source and a reading traveling body 32 including a mirror in order to perform scanning scanning of a document (not shown) placed on the contact glass 31. The image information scanned by the reading traveling body 32 is read as an image signal into the CCD 34 installed behind the lens 33, and the read image signal is digitized and subjected to image processing. Based on the image-processed signal, an electrostatic latent image is formed on the surface of the photosensitive member 1 by light emission of a laser diode (not shown) of the exposure device 6. The optical signal from the laser diode reaches the photosensitive member via a known polygon mirror or lens.

In the image forming apparatus having such a configuration, first, the photosensitive drum 1 is uniformly charged by the charging device 2 during rotation. Next, the optical writing unit 6 is driven based on image information read from the outside, whereby an electrostatic latent image is formed in the charging area (image forming area) of the photosensitive drum 1. The electrostatic latent image is developed by a developer (toner) supplied from the developing roller 3a of the developing unit 3 to become a visible toner image.

On the other hand, while the toner image is being formed on the photosensitive drum 1, the transfer paper 8 is pulled out from the paper feed cassette 7 by the paper feed roller 9, and the leading end thereof is brought into contact with the nip portion of the registration roller 11. Wait in contact. The transfer paper 8 is sent out to a transfer nip T1 formed by the photosensitive drum 1 and the transfer roller 10 when the registration roller 11 starts rotating at the timing when the toner image is superimposed on the photosensitive drum 1. It is. Then, after the toner image on the photosensitive drum 1 is transferred at the transfer nip T1, it is discharged by contact with a discharging brush (not shown). The discharged transfer paper 8 is mechanically separated from the photosensitive drum 1 and then sent to the fixing device 16.

The fixing device 16 sandwiches the transfer paper 8 between the fixing roller 14 and the press roller 15 to heat and pressurize the transfer paper 8 to fix the toner image on the transfer paper 8. The transfer paper 8 on which the toner image is fixed in this manner is discharged onto the stacker unit 17 by the paper discharge roller 18.

Residual toner remaining on the surface of the photosensitive drum 1 after passing through the transfer nip T1 is removed from the photosensitive drum 1 by the cleaning blade of the cleaning device 4 and collected.

In this image forming apparatus, the transfer paper transport path passing through the nip formed by the registration roller pair 11, the transfer nip T <b> 1, and the fixing nip T <b> 2 is transported substantially vertically from below to above. . In this way, the transfer paper 8 can be vertically conveyed to achieve downsizing and shortening of the first print time.

FIG. 4 is a partially enlarged view of the photoconductor and the vicinity thereof. In the image forming apparatus of the present embodiment, the photosensitive drum 1, the charging device 2, and the developing device are integrally configured as a process cartridge 110, and can be attached to and detached from the image forming apparatus main body. In the process cartridge 110, a photosensitive drum 1, a charging device 2, a developing device, and a cleaning device are provided in a layout as shown in the figure. The transfer roller 10 shown in FIG. 4 is provided in the image forming apparatus independently of the process cartridge 110, and is shown as a reference for layout.
As described above, a plurality of members including the charging device 2 and the photosensitive drum 1 are integrally configured as the process cartridge 110 and can be attached to and detached from the image forming apparatus main body.

An outline of the charging device 2 used in the image forming apparatus will be described.
FIG. 5 is an explanatory diagram of the charging device 2. The charging device 2 includes a charging roller 21 as a charging member, a sliding bearing 22, a spring 23 attached to the sliding bearing, and a power source (not shown). The charging roller includes a charging unit 21a and a journal unit 21b. Among these, the charging unit has a function of charging the surface of the photoconductor facing the photoconductor drum 1. The two journal parts are each supported by a slide bearing 22. A spring 23 is attached to the slide bearing 22 for pressing the charging roller toward the member to be charged. In the charging device 2 of the present embodiment, the charging roller is provided with a spacer portion which is a gap holding portion so that the charging portion 21a on the surface of the charging roller is opposed to the surface of the photoreceptor with a small gap.

The configuration of the spacer portion is as described above. One of the two sliding bearings 22 is made of a conductive material and is connected to a power source via a spring. As a result, a direct current (DC) bias from the power source or a superimposed bias in which an alternating current (AC) bias is superimposed on a direct current (DC) bias is applied to the charging portion of the charging roller via the spring → the conductive sliding bearing → the journal portion. It is to be applied.
In the present embodiment, the member to be charged by the charging device 2 is the photosensitive drum 1, but the charging device 2 shown in FIG. 5 may be used for charging another member to be charged such as transfer paper. Is possible.

It is an axial sectional view of the charging roller according to the present embodiment. It is a graph of the experimental result which shows the relationship between roller thickness and a gap. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a partially enlarged view of a photoconductor according to the present embodiment and its vicinity. 1 is a schematic configuration diagram of a charging device according to an embodiment. It is an axial sectional view of a charging roller according to a conventional embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Developing device 4 Cleaning device 8 Transfer paper 10 Transfer roller 11 Registration roller pair 12 Transfer paper conveyance path 14 Fixing roller 15 Press roller 16 Fixing device 21 Charging roller 21a Charging portion 21b Journal portion 22 Bearing 23 Spring 25 Base 26 Resistance layer 27 Convex forming member 100 Image forming unit 110 Process cartridge 200 Paper feed unit 300 Reading unit S Spacer T1 Transfer nip T2 Fixing nip

Claims (14)

A charging device having a charging member disposed opposite to a member to be charged and applying a voltage to the charging member to charge the member to be charged,
The charging member has a base, a resistance layer on the outer periphery of the base, and a spacer portion that comes into contact with the member to be charged,
In the charging device configured such that at least a part of the resistance layer forms a predetermined gap with the surface of the object to be charged by the spacer portion coming into contact with the object to be charged.
The charging device according to claim 1, wherein the spacer portion is installed in a recess having a reduced outer shape at both ends of the resistance layer. The charging device according to claim 1,
The said spacer part is comprised by inserting a ring-shaped roller in the said recessed part. The charging device characterized by the above-mentioned. The charging device according to claim 1 or 2,
The said recessed part is formed by cutting or grind | polishing a resistance layer. The charging device characterized by the above-mentioned. The charging device according to any one of claims 1 to 3,
The charging device, wherein the ring-shaped roller inserted into the concave portion is fixed to the resistance layer with an adhesive. The charging device according to claim 4,
The charging device according to claim 1, wherein the ring-shaped roller is made of a high-density polyethylene resin. The charging device according to any one of claims 1 to 5,
The charging device is characterized in that the resistance layer is formed of a resin composition containing carbon and a polymer type ion conductive material. The charging device according to claim 6,
The charging device, wherein the resin is a thermoplastic resin. The charging device according to claim 6,
The charging device, wherein the ion conductive material is a polymer compound containing a polyether ester amide component. The charging device according to any one of claims 1 to 8,
The charging device according to claim 1, wherein an outer diameter of the concave portion is in a range of "87 to 97"% with respect to an outer diameter of the resistance layer. The charging device according to any one of claims 1 to 9,
The charging device according to claim 1, wherein the predetermined gap between the resistance layer and the surface of the member to be charged is in the range of 10 to 50 μm. The charging device according to any one of claims 1 to 10,
The charging device according to claim 1, wherein a thickness of the ring-shaped roller is in a range of 2 to 6% with respect to an outer diameter of the resistance layer. In a process cartridge that is configured integrally with an image carrier and at least one of a charging device, a developing device, and a cleaning device, and is detachably formed on the image forming apparatus main body.
The process cartridge includes the charging device according to claim 1. An image forming apparatus comprising the process cartridge according to claim 12. An image forming apparatus comprising the charging device according to claim 1.

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