JP2006084724A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and a process cartridge which is capable of suppressing a charging sound up to a level of causing no problem in a practical use without using a means of raising a cost as the means for suppressing the charging sound generated when a charging member subjects an electrophotographic photoreceptor to application charging by superposing an alternating voltage to a direct voltage, has an excellent output image and facilitates the recycling of the mounted electrophotographic photoreceptor. <P>SOLUTION: The image forming apparatus is provided with the electrophotographic photoreceptor, a charging means, an image exposure means, a developing means, a transfer means and a cleaning means. The charging member of the charging means is composed of a main body part made of resin comprising a shaft part and conductive agent, is disposed oppositely in noncontact with the electrophotographic photoreceptor and subjects the electrophotographic photoreceptor to application charging in the noncontact state by superposing an alternating voltage to a direct voltage. When the gap between the charging member and the electrophotographic photoreceptor is G (μm) and the accuracy of outer diameter deviation upon the rotation by means of the center shaft of the electrophotographic photoreceptor is set to be A (μm), the image forming apparatus satisfies the relation; 10μm≤G-A≤90μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser printer, and a facsimile, and a process cartridge for an image forming apparatus including a charging unit and an electrophotographic photosensitive member disposed in the image forming apparatus.

In an image forming apparatus that forms an image using indirect electrophotography, such as a facsimile, a laser beam printer, a copying machine, etc., charging is mainly performed on an electrophotographic photosensitive member (hereinafter also simply referred to as “photosensitive member”). Each means such as image exposure, development, transfer, separation, cleaning, and charge removal is disposed, and image formation is performed on the photosensitive member in such a manner that each means operates in order.
First, the photosensitive member is charged (charged) at −400 to −800 volts by charging means. There are two methods for applying a voltage to the charging means: a case where a DC voltage is applied and a case where a DC voltage superimposed with an AC voltage is applied. Usually, it is possible to create an image with no problem in practice using only a DC voltage, but by superimposing an AC voltage on the DC voltage, it becomes less susceptible to environmental conditions, and charging that occurs when using the contact charging method. It is possible to reduce potential unevenness caused by unevenness of the member, the photosensitive member, minute unevenness of the member, and the like.
On the other hand, a charging method that is generally employed at present is that a high voltage of about −4000 to −6000 V is applied to a metal wire such as a tungsten wire or a nickel wire having a diameter of 40 to 80 μm that is built in a shield case. A corona charging method for charging a photosensitive member. A DC voltage of -1200 to -2000 V or a DC voltage of -500 to -900 V is applied to a charging member such as a roller shape or a brush shape having a resistance of about 10 ² to 10 ⁸ Ω · cm. In addition, a contact charging method in which the photosensitive member is charged while applying an alternating voltage of 1000 to 2500 V / 500 to 4500 Hz, or the charging member and the photosensitive member are arranged close to each other at a distance of about 30 to 250 μm. There is a non-contact charging method in which the voltage is applied to charge the photoreceptor.

Since a high voltage is applied in the corona charging method, ozone with a high concentration of around 10 ppm is generated. Therefore, there is an environmental problem due to ozone odor. Therefore, in recent years, a contact charging method capable of charging with a low applied voltage has been performed, and the generation of ozone is extremely low at 0.1 ppm or less. Therefore, in recent years, there are an increasing number of image forming apparatuses that use a contact charging method that generates a small amount of ozone and applies an alternating voltage superimposed DC voltage to the charging member.
However, when applied to a charging means in which an AC voltage is superimposed on a DC voltage, there is a noise problem that an irritating charging sound is generated during charging, in addition to the generation of ozone and nitrogen oxides that cause image quality degradation. There is. This charging sound is hardly a problem with a DC voltage, and is a phenomenon peculiar to alternating current because it is said to be an oscillating current. The larger the amplitude and the more easily the material that the support of the photoconductor resonates, the more the charging sound growing. Therefore, it is desirable to set the conditions as low as possible. However, if the charging stability is increased, the conditions become inevitably severe and the charging noise increases, so it is essential to take measures.
As means for improving this phenomenon, methods such as increasing the thickness of the support of the photosensitive member, inserting a damping material (filler) inside the drum-shaped photosensitive member, and improving the charging member side have been proposed. . These methods are aimed at suppressing the resonance of the photosensitive member and shifting the resonance frequency to a direction where it is difficult for the ears to be felt, and the following examples have been proposed.

For example, as a method for improving the generation of a charging sound (high frequency sound) during charging by inserting a damping material inside the drum-shaped photoconductor, a buffer material is press-fitted into the photosensitive drum (for example, Patent Document 1). See), filling the inside of the photoconductor with a viscoelastic material (for example, see Patent Document 2), and inserting a rigid body with a density of 2.0 g / cm ³ or more into the inside of the photoconductor (for example, see Patent Document 3) Inserting a member composed of two or more elastic bodies (O-rings) and a cylindrical member [a plastic having a specific gravity of 1.5 or more (polybutylene terephthalate resin containing 20% or more of glass fibers) into the photoreceptor. (For example, refer to Patent Document 4), a resin-made cylindrical member with a built-in metal spring is inserted, and fixed to the photosensitive body wall with a pressing force (for example, refer to Patent Document 5).
Further, as a method for increasing the thickness of the photoreceptor substrate to enhance the vibration damping effect, the vibration damping effect is obtained by setting the substrate of the photoreceptor body to have an inlay and the thickness other than the inlay to be 1.9 mm or more. (For example, see Patent Document 6), and obtaining a vibration damping effect by setting the volume density of the photoreceptor to 0.6 g / cm ³ or more and 2.0 g / cm ³ or less (for example, see Patent Document 7). Proposed.
Furthermore, as a method for achieving suppression of charging noise from the charging member, a coating layer is provided on the surface of the hollow charging member (roller), an elastic body is inserted into the charging member, and the cored bar is supported via the elastic body. It has been proposed to improve charging sound by adopting a structure (see, for example, Patent Document 8). The countermeasure method for charging noise differs depending on whether the vibration frequency of the photosensitive member is shifted to an audible range that does not cause an irritating effect or whether the vibration itself is suppressed.

  Each of the above methods has a greater or lesser effect. However, even if it is improved by the contact charging method, it may be difficult to obtain the effect by the non-contact charging method in which the charging member is disposed in close proximity to the photosensitive member. For example, it is difficult to obtain a sufficient effect only by a method of suppressing charging noise with a charging member or by simply increasing the thickness of the support of the photoreceptor. The method of increasing the weight by inserting a filler inside the photoconductor support and suppressing the sound (squeal) is effective, but even if it is simply inserted, there is a gap between the support and the insert When the weight is small, it is difficult to obtain the expected effect. In addition, the effect may be reduced when it is composed of a single member. Furthermore, in recent years, there is an environmental problem that needs to be recycled, reused, etc., so this point needs to be considered.

JP-A 63-60481 (pages 2 to 3) Japanese Patent Laid-Open No. 3-105348 (pages 2 to 5) JP-A-5-197321 (Claims, pages 8 to 10) JP 11-184308 A (claims, pages 2 to 3) JP 2000-321929 A (pages 2 to 4) JP 2000-19761 A (pages 2 to 3) JP 2000-155500 A (pages 2 to 3) JP-A-9-230671 (Claims, pages 3 to 10)

  An object of the present invention is to mount a damping material inside the photosensitive member as a means for suppressing charging noise generated when the charging member superimposes an alternating current voltage on a direct current voltage to apply and charge the electrophotographic photosensitive member. An image forming apparatus that can suppress charging noise to a level that does not cause a problem in practice without using a means that increases costs, has an excellent output image, and facilitates recycling of the mounted electrophotographic photosensitive member, and To provide a process cartridge that can be attached to and detached from the image forming apparatus.

As a result of intensive studies on the above problems, the present inventors have found that the above problems are solved by the following inventions 1) to 24) (hereinafter referred to as the present inventions 1 to 24).
1) At least an electrophotographic photosensitive member, a charging unit that uniformly charges the electrophotographic photosensitive member, an image exposing unit that forms an electrostatic latent image by performing image exposure after uniform charging, and a toner on the electrostatic latent image An image forming apparatus comprising: a developing unit for developing; a unit for transferring a developed image; and a cleaning unit for cleaning a transfer residual toner of the electrophotographic photosensitive member, wherein the charging member used in the charging unit is an electrophotographic photosensitive member The charging member is arranged to face and charge the electrophotographic photosensitive member in a non-contact manner by superimposing an alternating current voltage on a direct current voltage, and covering the shaft portion and the shaft portion. The main body is made of resin containing a conductive agent, and the size of the gap formed between the charging member and the electrophotographic photosensitive member is G (μm), and rotates around the central axis of the electrophotographic photosensitive member. Outer diameter runout when letting The when the A ([mu] m), the image forming apparatus G and A and satisfies the following relationship.
10 (μm) ≦ GA ≦ 90 (μm)
2) The image forming apparatus according to 1), wherein a size G of the gap satisfies a relationship of 20 (μm) ≦ G ≦ 100 (μm).
3) The image forming apparatus according to 1) or 2), wherein the outer diameter deflection accuracy A satisfies a relationship of 10 (μm) ≦ A ≦ 50 (μm).
4) The charging member is characterized in that a gap member is formed between the charging member and the image bearing member by providing a spacer member in a main body portion that contacts the outside of the image forming area of the electrophotographic photosensitive member disposed to face the charging member. The image forming apparatus according to any one of 1) to 3).
5) The image forming apparatus according to any one of 1) to 4), wherein an AC voltage frequency supplied by the charging member to charge the electrophotographic photosensitive member is 100 Hz to 2.5 kHz.
6) The vibration amplitude (Vpp) of the AC voltage frequency supplied to charge the electrophotographic photosensitive member by the charging member is 1.0 to 3.0 kV, any one of 1) to 5) The image forming apparatus described in 1.
7) The image forming apparatus according to any one of 1) to 6), wherein the volume resistivity of the main body is 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm.
8) The electrophotographic photosensitive member has a photosensitive layer, a charge transport layer as an outermost surface layer, and the charge transport layer has a thickness of 10 to 35 μm. An image forming apparatus according to claim 1.
9) The image forming apparatus according to any one of 1) to 8), wherein the electrophotographic photosensitive member is provided with bearing members in openings at both ends, and includes a shaft penetrating the inside of the photosensitive member.
10) Any of 1) to 9), wherein the electrophotographic photosensitive member operates with the charging member during operation, and the electrophotographic photosensitive member rotates and charges at 200 rpm or less when applied by the charging member. An image forming apparatus according to claim 1.
11) The image forming apparatus according to any one of 1) to 10), wherein the toner used in the developing unit contains inorganic fine particles having an average particle diameter of 70 to 300 nm.
12) At least a charging unit that uniformly charges the electrophotographic photosensitive member, an image exposure unit that forms an electrostatic latent image by performing image exposure after being uniformly charged, a developing unit that develops toner on the electrostatic latent image, One or more means including a charging means among developed image transfer means and an electrophotographic photosensitive member, and a charging member used in the charging means is opposed to the electrophotographic photosensitive member in a non-contact manner. The charging member is configured to superimpose an AC voltage on a DC voltage to apply and charge the electrophotographic photosensitive member in a non-contact manner, and includes a shaft portion and a body portion covering the shaft portion. It is made of a resin containing a conductive agent, and the size of the gap formed between the charging member and the electrophotographic photosensitive member is G (μm), and the outer diameter shake accuracy when rotated around the central axis of the electrophotographic photosensitive member is When A (μm), G and A satisfy the relationship of the following formula Free process cartridge detachable to an image forming apparatus according to claim and.
10 (μm) ≦ GA ≦ 90 (μm)
13) The process cartridge according to 12), wherein the size G of the gap satisfies a relationship of 20 (μm) ≦ G ≦ 100 (μm).
14) The process cartridge according to 12) or 13), wherein the outer diameter deflection accuracy A satisfies a relationship of 10 (μm) ≦ A ≦ 50 (μm).
15) The charging member is provided with a spacer member in a main body portion that contacts the outside of the image forming area of the electrophotographic photosensitive member arranged opposite to each other, thereby forming a gap between the charging member and the electrophotographic photosensitive member. The process cartridge according to any one of 12) to 14).
16) The process cartridge according to any one of 12) to 15), wherein an AC voltage frequency supplied for charging the electrophotographic photosensitive member by the charging member is 100 Hz to 2.5 kHz.
17) The vibration amplitude (Vpp) of the AC voltage frequency supplied to charge the electrophotographic photosensitive member by the charging member is 1.0 to 3.0 kV, any of 12) to 16) Process cartridge according to.
18) The process cartridge according to any one of 12) to 17), wherein the volume resistivity of the main body is 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm.
19) Any of 12) to 18), wherein the electrophotographic photosensitive member has a photosensitive layer, a charge transport layer as an outermost surface layer, and the charge transport layer has a thickness of 10 to 35 μm. The process cartridge according to the above.
20) The process cartridge according to any one of 12) to 19), wherein the electrophotographic photosensitive member includes a shaft having a bearing member attached to openings at both ends and penetrating through the inside of the photosensitive member.
21) Any of 12) to 20), wherein the electrophotographic photosensitive member operates with the charging member during operation, and the electrophotographic photosensitive member rotates and charges at 200 rpm or less when applied by the charging member. The process cartridge according to the above.
22) The process cartridge according to any one of 12) to 21), wherein the toner used in the developing unit contains inorganic fine particles having an average particle diameter of 70 to 300 nm.
23) An image forming apparatus comprising a plurality of process cartridges according to any one of 12) to 22).
24) An image forming apparatus having an intermediate transfer unit that primarily transfers a toner image developed on the electrophotographic photosensitive member onto an intermediate transfer member and then secondary-transfers the toner image on the intermediate transfer member onto a recording material. The image forming apparatus according to any one of 1) to 11) and 23), wherein toner images of a plurality of colors can be secondarily transferred onto a recording material at once.

Hereinafter, the present invention will be described in detail.
In the image forming apparatus or the process cartridge of the present invention, the charged sound can be suppressed to a level that does not cause a problem in practice, and the mounted electrophotographic photosensitive member does not include a vibration damping material inside, and thus can be easily recycled. is there. Further, the process cartridge needs to include at least a charging unit having the characteristics of the present invention and an electrophotographic photosensitive member.
The reason why the charging noise can be suppressed is not clarified, but the main body part of the charging member is formed of a resin containing a conductive agent, so that the formation accuracy of the main body part is higher than that of a charging member formed of rubber. As a result, the outer diameter deflection accuracy is improved, and the size of the gap between the electrophotographic photosensitive member and the charging member is hardly changed. Further, since the resin charging member is harder to be deformed than the rubber charging member, it is difficult to cause deformation during operation in the image forming apparatus, and the size of the gap between the electrophotographic photosensitive member and the charging member is less likely to change. Therefore, since the resin charging member can stably charge the electrophotographic photosensitive member in a non-contact manner, it is presumed that the charging sound will be smaller than that of the rubber charging member.

Hereinafter, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view for explaining an image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 1, 11 is an electrophotographic photosensitive member that satisfies the requirements of the present invention.
The photoconductor 11 has a drum shape, but may have a sheet shape or an endless belt shape. A charging roller is used as the charging member 12. The charging member 12 is disposed to face the photoconductor 11 with a minute gap G therebetween. The gap G is adjusted by providing a spacer member having a certain thickness in the non-image forming area of the charging member 12.
As the transfer means 16, the above charging roller can be generally used, but a combination of a transfer charger and a separation charger is effective.

Further, as a light source used for the exposure means 13, the static elimination means 1A, etc., a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), etc. Listed are all luminescent materials. In order to irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used.
The toner 15 developed on the photoconductor by the developing means 14 is transferred to the image receiving medium 18, but not all is transferred, and some toner remains on the photoconductor. Such toner is removed from the photoreceptor by the cleaning means 17. As the cleaning means, a rubber cleaning blade, a brush such as a fur brush, a mag fur brush, or the like can be used.

The toner used in the developing means can output a high-quality image by containing inorganic fine particles having an average particle diameter of 70 to 300 nm.
When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with toner of negative (positive) polarity (electrodetection fine particles), a positive image can be obtained, and if developed with toner of positive (negative) polarity, a negative image can be obtained. A known method is applied to such a developing unit, and a known method is also used for the charge eliminating unit.
The above electrophotographic process exemplifies an embodiment of the present invention, and other embodiments are of course possible.
Further, the image forming means as described above may be fixedly incorporated in a copying machine, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is an apparatus (part) that contains an electrophotographic photosensitive member and includes at least one of charging means, exposure means, developing means, transfer means, cleaning means, and static elimination means. The process cartridge has various shapes and the like, and a typical example is shown in FIG.

FIG. 3 shows another example of the image forming apparatus of the present invention. In this electrophotographic apparatus, a charging member 12, which is a charging means, an exposure means 13, a black (Bk), a cyan (C), a magenta (M), and a yellow (Y) toner for each color toner is developed around the photoconductor 11. Means (14Bk, 14C, 14M, 14Y), an intermediate transfer belt 1F as an intermediate transfer member, and a cleaning means 17 are arranged in this order. Here, the subscripts Bk, C, M, and Y shown in the drawing correspond to the color of the toner described above, and may be added or omitted as appropriate.
Each color developing means 14Bk, 14C, 14M, 14Y can be controlled independently, and only the color developing means for image formation is driven. The toner image formed on the photoreceptor 11 is transferred onto the intermediate transfer belt 1F by the first transfer unit 1D disposed inside the intermediate transfer belt 1F. The first transfer unit 1D is disposed so as to be able to come into contact with and separate from the photoconductor 11, and the intermediate transfer belt 1F is brought into contact with the photoconductor 11 only during the transfer operation. The respective color images are sequentially formed, and the toner images superimposed on the intermediate transfer belt 1F are collectively transferred to the image receiving medium 18 by the second transfer unit 1E and then fixed by the fixing unit 19 to form an image. . The second transfer unit 1E is also arranged so as to be able to contact and separate from the intermediate transfer belt 1F, and contacts the intermediate transfer belt 1F only during the transfer operation.

In the transfer drum type image forming apparatus, since the toner images of the respective colors are sequentially transferred onto the transfer material electrostatically attracted to the transfer drum, there is a restriction on the transfer material that cannot be printed on thick paper, as shown in FIG. Such an intermediate transfer type electrophotographic apparatus is characterized in that the toner images of the respective colors are superposed on the intermediate transfer belt 1F, so that the transfer material is not limited. Such an intermediate transfer method is not limited to the apparatus shown in FIG. 3, but can be applied to the image forming apparatus and the process cartridge shown in FIGS.
FIG. 4 is a cross-sectional view in the radial direction of a charging member used for the charging means. The charging member 12 has a structure in which a shaft portion 12a made of a metal core is formed at the center and a main body portion 12b is formed on the outside thereof. The shaft portion 12a is made of, for example, a metal having high rigidity and conductivity, such as stainless steel or aluminum having a diameter of 8 to 20 mm, or 1 × 10 ³ Ω · cm or less, preferably 1 × 10 ² Ω · cm or less. It is comprised with the conductive resin etc. which have rigidity. The main body 12b preferably has a volume resistivity of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm and a thickness of about 1 to 2 mm. If the volume resistivity of the main body portion 12b exceeds 1 × 10 ¹⁰ Ω · cm, the discharge becomes insufficient and the surface of the photoconductor 11 may not be sufficiently charged. Conversely, the volume resistivity is 1 ×. If it is less than 10 ⁵ Ω · cm, if the photosensitive layer of the photoconductor 11 has a defect such as a pinhole, the discharge current concentrates on the pinhole, causing an abnormal discharge, and the overcurrent expands the pinhole. The photosensitive layer is destroyed and an abnormal image is output.

Although FIG. 4 shows the case of the single layer structure as the main body portion 12b, the main body portion 12b is not particularly limited to this structure, and may be composed of two or more layers of conductive resin or the like. Conventionally, rubber such as hydrin rubber has been used for the main body portion 12b, but here, a resin having a lower expansion coefficient than that of rubber is used to mix a conductive agent to adjust electric resistance. Usually, the linear expansion coefficient of resin is about 1/2 or less than that of rubber, and the volume expansion coefficient of resin is about 1/6 or less of rubber when isotropic. When rubber is used as in the prior art, the gap G fluctuates due to a large change in the dimensional accuracy of the rubber due to heat and humidity. Therefore, when the gap G between the charging member 12 and the photoconductor 11 is small,
10 (μm) ≦ GA
In other words, the charging member and the electrophotographic photosensitive member may come into contact with each other, which may increase the charging noise or cause uneven charging due to abnormal discharge. On the other hand, when the gap G between the charging member 12 and the photoconductor 11 is sufficiently large and the outer diameter deflection accuracy A is sufficiently small,
G-A ≦ 90 (μm)
In other words, the image quality of the output image may be deteriorated, for example, the charged potential on the surface of the photoconductor 11 is lowered and the background of the output image is likely to be stained.

Examples of the resin used for the main body portion 12b include olefin resins such as polyethylene and polypropylene, styrene resins such as polystyrene and copolymers thereof, and acrylic resins such as polymethyl methacrylate.
Examples of the conductive agent mixed in the resin include alkali metal salts such as lithium peroxide, perchlorates such as sodium perchlorate, quaternary ammonium salts such as tetrabutylammonium salts, and ionic conductive agents such as polymer conductive agents. Further, metal powder such as carbon black, silver powder and copper powder, and ceramic powder such as ITO can be used.
In order to improve the strength and dimensional accuracy in addition to the conductive agent, the resin can be mixed with ceramics such as carbon fiber, glass fiber, carbide, boride and the like to reduce the expansion coefficient.

FIG. 5 is a schematic view of a charging member used in the image forming apparatus of the present invention. The charging member is provided with spacer members 30 at both ends of the main body. The gap G between the charging member 12 and the photoconductor 11 is set to 100 μm or less, particularly 20 to 50 μm, by the spacer member. This can suppress the formation of abnormal images when the charging device is in operation. When the gap G exceeds 100 μm, the image quality of the output image may be deteriorated, for example, the background potential of the surface of the photoconductor 11 is lowered and the output image is easily soiled. If the gap G is smaller than 20 μm, the deposit on the surface of the photosensitive member that has not been removed by the cleaning member comes into contact with the charging member, so that a part of the adhered material is transferred to the charging member, and charging unevenness when the photosensitive member is charged is It can be a cause.
The spacer member 30 may be made of an olefin resin such as polyethylene or polyolefin, a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, or a fluorine resin such as polytetrafluoroethylene.

  The spacer member 30 can be made of elastic metal or rubber. As the metal, aluminum, iron, copper, titanium, or an alloy mainly composed of these can be used. Furthermore, it is preferable to coat these surfaces with an oxide to make them electrically insulating. Since the metallic spacer member 30 is harder than the photosensitive layer made of the resin of the photoreceptor 11, it is preferable to coat the surface with the resin. As a result, the hardness of the photosensitive layer of the photoconductor 11 can be made lower and the wear of the photoconductor 11 can be reduced. As the rubber, natural rubber, polyurethane rubber, chloroprene rubber, nitrile-butadiene rubber, silicone rubber, and fluorine rubber can be used. JIS-A: The rubber hardness is preferably 70 Hs or more, and more preferably one obtained by adding silica, alumina, glass fiber or the like and curing. Thereby, the fluctuation | variation of the gap | interval G can be prevented.

When charging the photosensitive member with the charging member 12 disposed opposite to the photosensitive member 11, the voltage applied to the charging member 12 is sufficient when the photosensitive member 11 and the charging member 12 are in contact with each other only with a DC voltage. Therefore, it is possible to provide a high level of practicality, and there is no charging noise at a level that causes a practical problem. However, in the case of non-contact, when charging is performed only with a DC voltage, uneven charging tends to occur significantly. Therefore, it is necessary to suppress the occurrence of charging unevenness by superimposing the AC voltage on the DC voltage and compensating with the AC voltage.
The AC voltage is preferably a sine wave, and the frequency is preferably set to 100 Hz to 2.5 kHz. If the frequency is less than 100 Hz, the AC voltage does not sufficiently act on the photosensitive member, so that uneven charging tends to occur and abnormal images are likely to occur. If the frequency exceeds 2.5 kHz, abnormal discharge is likely to occur, and the charges trapped in the photosensitive layer of the photosensitive member lower the charging potential, destabilizing the repeated characteristics of the charging potential, thereby causing background stains. cause.
The frequency of the alternating voltage applied to the charging member varies in a suitable value depending on the linear velocity of the photosensitive member, but if set to 800 Hz to 2 kHz, there is no practical problem.

The vibration amplitude (Vpp) of the AC voltage frequency is preferably 1.0 to 3.0 kV. Within this range, a stable photosensitive member charging potential can be obtained, and an increase in the residual potential of the photosensitive member due to repeated use can be moderately suppressed. However, as Vpp increases, the charging noise increases, so that 2.5 kV or less. Is more desirable. If it is less than 1.3 kV, the photosensitive member may be partially insufficiently charged, resulting in uneven charging and an abnormal image.
It is desirable to increase the AC voltage frequency and Vpp in order to uniformly charge the target potential without uneven charging as the rotational speed at the time of charging of the photoreceptor increases. However, since there are suitable ranges for the AC voltage frequency and Vpp as described above, it is desirable to rotate and charge the photosensitive member at 200 rpm or less.
The outer diameter deflection accuracy A of the photoconductor 11 is set to 10 to 50 μm. As the outer diameter shake accuracy increases, color misregistration is likely to occur, and the image quality of the output image may be degraded. When the thickness is less than 10 μm, the manufacturing cost is significantly increased as compared with a thickness of 10 μm or more, and it is not possible to achieve the problem of suppressing the charged sound to a level that does not cause a practical problem without using a means for increasing the cost. In order to improve the outer diameter deflection accuracy A, bearing members may be attached to the openings at both ends of the photoconductor 11 to provide shafts that penetrate the photoconductor. For example, the outer diameter deflection accuracy A can be improved by providing a resin precision bearing member with a metal precision shaft penetrating the inside of the photoreceptor.

  FIG. 6 is a structural example (schematic cross-sectional view) of an electrophotographic photoreceptor provided in the image forming apparatus of the present invention, and shows an electrophotographic photoreceptor having a construction in which a photosensitive layer is provided on a conductive support. . 7 and 8 each show a configuration example (schematic cross-sectional view) of another electrophotographic photosensitive member provided in the image forming apparatus of the present invention. FIG. 7 shows a function-separated type electrophotographic photoreceptor in which the photosensitive layer is composed of a charge generation layer (CGL) and a charge transport layer (CTL). FIG. 8 shows a conductive support and a function-separated type electrophotographic photoreceptor. An electrophotographic photosensitive member is shown in which an undercoat layer is inserted between CGL and CTL of the photosensitive layer. The electrophotographic photoreceptor used in the present invention may have other layers other than the above as long as it has at least a photosensitive layer on a conductive support and the outermost surface layer is a charge transport layer. Absent.

As the conductive support used in the electrophotographic photosensitive member in the present invention, a conductor or an insulator subjected to a conductive treatment, for example, a metal such as Al, Ni, Fe, Cu, Au, or an alloy thereof, polyester, A thin film of a metal such as Al, Ag or Au or a conductive material such as In ₂ O ₃ or SnO ₂ on an insulating substrate such as polycarbonate, polyimide or glass, carbon black, graphite or metal powder in the resin (Aluminum, copper, nickel, etc.), conductive glass powder or the like is uniformly dispersed, and a resin substrate in which conductivity is imparted to the resin, paper subjected to conductive treatment, or the like can be used. The shape of the conductive support is not particularly limited, and any of a plate shape, a drum shape, and a belt shape can be used. However, when a belt-like support is used, it is necessary to provide a driving roller and a driven roller inside. While the equipment becomes complicated and large, there are advantages such as increased flexibility in layout. However, when forming a protective layer, there is a possibility that cracks called cracks may occur on the surface due to insufficient flexibility of the protective layer, which may cause granular background stains. It is done. For this reason, a drum having a high rigidity is preferably used as the support.

An undercoat layer may be provided between the conductive support and the photosensitive layer as necessary. The undercoat layer is provided for the purpose of improving adhesiveness, preventing moire, improving the coatability of the upper layer, and reducing the residual potential. The undercoat layer generally contains a resin as a main component, but these resins are resins having a high solubility resistance to general organic solvents in consideration of applying a photosensitive layer thereon using a solvent. It is desirable to be. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resins, alkyd-melamine resins, and epoxy resins. Examples thereof include curable resins that form a three-dimensional network structure. Further, fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like, or metal sulfides and metal nitrides may be added. These undercoat layers can be formed by a common coating method using an appropriate solvent.
Furthermore, a metal oxide layer formed by using, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful as the undercoat layer. In addition, as an undercoat layer, an anodized layer of Al ₂ O ₃ , an organic material such as polyparaxylylene (parylene), or an inorganic material such as SnO ₂ , TiO ₂ , ITO, or CeO ₂ is vacuumed. You may provide by a thin film preparation method.
The thickness of the undercoat layer is suitably about 0.1 to 5 μm.

The charge generation layer is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. As the charge generation material, inorganic materials and organic materials can be used.
Examples of inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, and selenium-arsenic compounds.
On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments.
These charge generation materials can be used alone or as a mixture of two or more.

As a binder resin used as necessary for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, Examples include polyacrylamide. These binder resins can be used alone or as a mixture of two or more.
Moreover, you may add a charge transport substance as needed. In addition to the binder resin described above, a polymer charge transporting material is also preferably used as the binder resin for the charge generation layer.
As a method for forming the charge generation layer, a vacuum thin film preparation method and a casting method from a solution dispersion system can be largely mentioned.
Examples of the vacuum thin film preparation method include a glow discharge polymerization method, a vacuum deposition method, a CVD method, a sputtering method, a reactive sputtering method, an ion plating method, and an accelerated ion injection method. In this method, the above-described inorganic material or organic material can be favorably formed.
Further, in order to provide the charge generation layer by the casting method, a ball mill, an attritor or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone together with the above-described inorganic or organic charge generation material, if necessary, with a binder resin. It can be formed by dispersing with a sand mill or the like, and applying the solution after diluting the dispersion appropriately. The application can be performed using a commonly used method such as a dip coating method, spray coating, or bead coating.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

The charge transport layer is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer by exposure to the charged charge that has been held. In order to achieve the purpose of holding the charged charge, it is required that the electric resistance is high. Further, in order to achieve the purpose of obtaining a high surface potential with the charged charge that has been held, it is required that the dielectric constant is small and the charge mobility is good.
The charge transport layer for satisfying these requirements is composed of a charge transport material and a binder resin used as required, and the charge transport material and the binder resin are dissolved or dispersed in an appropriate solvent and coated. It can be formed by drying. If necessary, additives such as a plasticizer, an antioxidant, a leveling agent and the like can be added to the charge transport layer in addition to the charge transport material and the binder resin.

Examples of the charge transport material include a hole transport material and an electron transport material.
Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more.
As the hole transport material, an electron donating material is preferably used. Examples of electron donating substances include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane , Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like.
These hole transport materials can be used alone or as a mixture of two or more.

Further, the polymer charge transporting material may have the following structure.
(A) Polymer having carbazole ring For example, poly-N-vinylcarbazole, JP-A-50-82056, JP-A-54-9632, JP-A-54-11737, JP-A-4-175337 And the compounds described in JP-A-4-183719 and JP-A-6-234841.
(B) Polymer having a hydrazone structure For example, JP-A-57-78402, JP-A-61-20953, JP-A-61-296358, JP-A-1-134456, JP-A-1-134456 179164, JP-A-3-180851, JP-A-3-180852, JP-A-3-50555, JP-A-5-310904, JP-A-6-234840, and the like. Is done.
(C) Polysilylene polymer For example, JP-A-63-285552, JP-A-1-88461, JP-A-4-264130, JP-A-4-264131, JP-A-4-264132, Examples thereof include compounds described in Kaihei 4-264133 and JP-A-4-289867.
(D) Polymer having a triarylamine structure For example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-134457, JP-A-2-282264, JP-A-2- Examples include compounds described in JP-A-304456, JP-A-4-133605, JP-A-4-133066, JP-A-5-40350, and JP-A-5-202135.
(E) Other polymers For example, formaldehyde condensation polymer of nitropyrene, JP-A-51-73888, JP-A-56-150749, JP-A-6-234836, JP-A-6-234837 The described compounds and the like are exemplified.

The polymer having an electron donating group used in the present invention is not limited to the above-mentioned polymer, but also a copolymer of a known monomer, a block polymer, a graft polymer, a star polymer, It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-109406.
Further, examples of polycarbonates, polyurethanes, polyesters, and polyethers having a triarylamine structure that are further useful as the polymer charge transporting material used in the present invention include, for example, JP-A 64-1728 and JP-A 64- 13061, JP 64-19049, JP 4-11627, JP 4-225014, JP 4-230767, JP 4-320420, JP 5-232727 JP, 7-56374, JP 9-127713, JP 9-222740, JP 9-265197, JP 9-211877, JP 9-304956. And the like.
Furthermore, as a binder resin that can be used in combination with the charge transport layer, for example, polycarbonate, polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenol resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, Silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyacrylate, polyacrylamide, phenoxy resin, and the like are used. These binder resins can be used alone or as a mixture of two or more.

The thickness of the charge transport layer is suitably about 5 to 100 μm. However, due to the recent demand for higher image quality, the charge transport layer has been made thinner, in order to achieve higher image quality of 1200 dpi or more. Is more preferably about 10 to 35 μm.
In the charge transport layer in the present invention, additives such as other antioxidants and plasticizers used for rubbers, plastics, oils and the like may be added.
Furthermore, a leveling agent may be added to the charge transport layer. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 100 parts by weight of binder resin. 0 to 1 part by weight is appropriate.
As the coating method, a conventional method such as a dip coating method, spray coating, or bead coating method can be used.

  According to the present invention, as a means for suppressing charging noise generated when the charging member superimposes an AC voltage on a DC voltage to apply and charge the electrophotographic photosensitive member, a damping material is mounted inside the photosensitive member. An image forming apparatus that can suppress charging noise to a level that does not cause a problem in practice without using a means that increases costs, has an excellent output image, and facilitates recycling of the mounted electrophotographic photosensitive member, and A process cartridge that can be attached to and detached from the image forming apparatus can be provided. In addition, since the mounted electrophotographic photosensitive member does not include a vibration damping material, it can be easily recycled.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these Examples.

次に、テトラヒドロフラン１００重量部に、ビスフェノールＺ型ポリカーボネート樹脂１０重量部、シリコーンオイル〔ＫＦ−５０（信越化学工業社製）〕０．００２重量部を溶解し、これに下記構造式〔化２〕の電荷輸送物質１０重量部を加えて電荷輸送層用塗工液を作製した。こうして得られた電荷輸送層用塗工液を電荷発生層上に浸漬塗工法によって塗工し、その後１１０℃で２０分間乾燥して、厚み３１μｍの電荷輸送層を形成した。

電子写真感光体の帯電条件等は、画像部電位−４０Ｖ、非画像部電位−５００Ｖ、感光体の線速１５５ｍｍ／ｓｅｃとした。
感光体には両端の開口部に軸受け部材が装着され、感光体内部を貫通する軸を具備しており、外径振れ精度を２５μｍとした。
＜帯電部材＞
ステンレススチール製の芯軸（φ８ｍｍ導電性支持体）を本体部として樹脂で被覆した図４に示す構造の帯電ローラを製作した。樹脂材料としては、ＡＢＳ樹脂１００重量部に導電剤としてエーテルアミド０．５重量部を配合し、体積抵抗率が１×１０^８Ω・ｃｍ〜１×１０^９Ω・ｃｍとなるよう調整した組成物を用い、この材料を押出成形機により成形して芯軸を被覆し、φ１１ｍｍの帯電ローラを得た。スペーサ部材には熱収縮性フッ素樹脂を用いた。加えた電圧条件は交流電圧周波数１．１ｋＨｚ、Ｖｐｐ ２．０ｋＶ、直流電圧−４５０Ｖであり、電子写真感光体と帯電部材の間隙Ｇは５０μｍとした。 Example 1
The following were mounted as the electrophotographic photosensitive member 11 and the charging member 12 on a modified Ricoh Ipsio Color 8100. The toner used contained at least inorganic fine particles having an average particle diameter of 70 to 300 nm and an average particle diameter of 5.9 μm.
Print a mixed image of rectangular patches and characters with an image density of 5%, measure the volume at 30 cm in front of the modified Ipsio Color 8100, average the magnitude of 1 to 4 overtones of the charged sound, did. This volume includes sounds other than charged noise such as background noise. In addition, the presence or absence of soiling was evaluated as the image quality.
<Electrophotographic photoreceptor>
15 parts by weight of alkyd resin [Beckolite M6401-50 (manufactured by Dainippon Ink & Chemicals)], 10 parts by weight of melamine resin [Super Becamine G-821-60 (manufactured by Dainippon Ink & Chemicals)], 150 parts by weight of methyl ethyl ketone 90 parts by weight of titanium oxide powder [TAIPALE CR-EL (manufactured by Ishihara Sangyo Co., Ltd.)] was added thereto and dispersed in a ball mill for 12 hours to prepare an undercoat layer coating solution.
This was coated on a cylindrical aluminum substrate having a diameter of 30 mm by a dip coating method and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 4.5 μm.
Next, 4 parts by weight of polyvinyl butyral resin [XYHL (manufactured by UCC)] is dissolved in 150 parts by weight of cyclohexanone, 10 parts by weight of a bisazo pigment of the following structural formula [Chemical Formula 1] is added thereto, and dispersed for 48 hours by a ball mill. Further, 210 parts by weight of cyclohexanone was added and dispersed for 3 hours. This was transferred to a container and diluted with cyclohexanone so that the solid content was 1.5% by weight. The charge generation layer coating solution thus obtained was applied onto the intermediate layer and dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.2 μm.

Next, in 100 parts by weight of tetrahydrofuran, 10 parts by weight of bisphenol Z-type polycarbonate resin and 0.002 parts by weight of silicone oil [KF-50 (manufactured by Shin-Etsu Chemical Co., Ltd.)] are dissolved. 10 parts by weight of the charge transport material was added to prepare a charge transport layer coating solution. The charge transport layer coating solution thus obtained was applied onto the charge generation layer by dip coating, and then dried at 110 ° C. for 20 minutes to form a charge transport layer having a thickness of 31 μm.

The charging conditions of the electrophotographic photosensitive member were an image portion potential of −40 V, a non-image portion potential of −500 V, and a photosensitive member linear velocity of 155 mm / sec.
The photoconductor is provided with bearing members in the openings at both ends, and has a shaft that penetrates the inside of the photoconductor, and the outer diameter deflection accuracy is 25 μm.
<Charging member>
A charging roller having a structure shown in FIG. 4 in which a stainless steel core shaft (φ8 mm conductive support) was coated with a resin as a main body was manufactured. As a resin material, a composition prepared by blending 0.5 parts by weight of ether amide as a conductive agent with 100 parts by weight of ABS resin and adjusting the volume resistivity to 1 × 10 ⁸ Ω · cm to 1 × 10 ⁹ Ω · cm. This material was molded by an extruder and the core shaft was covered to obtain a charging roller having a diameter of 11 mm. A heat-shrinkable fluororesin was used for the spacer member. The applied voltage conditions were AC voltage frequency 1.1 kHz, Vpp 2.0 kV, DC voltage −450 V, and the gap G between the electrophotographic photosensitive member and the charging member was 50 μm.

Examples 2-7
Evaluation was performed in the same manner as in Example 1 except that the gap G and the outer diameter deflection accuracy A were changed as shown in Table 1.

Examples 8-9
Evaluation was performed in the same manner as in Example 1 except that the gap G and the outer diameter deflection accuracy A were changed as shown in Table 1 and Vpp was set to 1.7 kV or 2.5 kV.

Example 10
Evaluation was performed in the same manner as in Example 1 except that the thickness of the charge transport layer (CTL) of the photoreceptor was 20 μm.

Example 11
Evaluation was performed in the same manner as in Example 1 except that the linear velocity of the photoreceptor was 77.5 mm / sec.

Comparative Example 1
Evaluation was performed in the same manner as in Example 1 except that the electrophotographic photosensitive member and the charging member were brought into contact with each other because the spacer member was not provided.

Comparative Examples 2-4
Evaluation was performed in the same manner as in Example 1 except that the gap G and the outer diameter deflection accuracy A were changed as shown in Table 1.

Comparative Example 5
Evaluation was performed in the same manner as in Example 1 except that only the DC voltage was applied to the charging member.

Comparative Example 6
Evaluation was performed in the same manner as in Example 1 except that the charging member was changed to the following.
Charging member A charging roller having a structure shown in FIG. 4 was manufactured by coating a stainless steel core shaft (φ8 mm conductive support) with a semiconductive elastic layer as a main body. 100 parts by weight of a thermoplastic elastomer containing a polyester component as an elastic material is blended with 0.5 parts by weight of lithium perchlorate so that the volume resistivity is 1 × 10 ⁸ Ω · cm to 1 × 10 ⁹ Ω · cm. Using this composition, the material was molded by an extruder and the core shaft was covered to obtain a charging roller having a diameter of 11 mm.

表１から分るように、本発明の構成要件を満たす実施例では、帯電音の音量が低減し、帯電不良による地汚れが見られない極めて高画質な画像を得られることが確認された。一方、本発明の要件を満たしていない比較例では、何れも帯電音の音量の増大、又は帯電不良による地汚れが見られ異常画像が発生した。 The evaluation results of Examples 1 to 11 and Comparative Examples 1 to 6 are summarized in Table 1.

As can be seen from Table 1, it was confirmed that in the examples satisfying the constitutional requirements of the present invention, the sound volume of the charged sound was reduced, and an extremely high quality image with no background stain due to poor charging could be obtained. On the other hand, in all of the comparative examples not satisfying the requirements of the present invention, an abnormal image was generated due to an increase in the volume of the charging sound or scumming due to poor charging.

1 is a schematic diagram for explaining an image forming apparatus of the present invention. The figure which shows the example of a general shape of a process cartridge. FIG. 6 is a diagram showing another example of the image forming apparatus of the present invention. Sectional drawing of the radial direction of the charging member used for a charging means. FIG. 2 is a schematic diagram of a charging member used in the image forming apparatus of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration example of an electrophotographic photosensitive member included in the image forming apparatus of the present invention. FIG. 6 is a schematic cross-sectional view showing another configuration example of the electrophotographic photosensitive member provided in the image forming apparatus of the present invention. FIG. 6 is a schematic cross-sectional view showing another configuration example of the electrophotographic photosensitive member provided in the image forming apparatus of the present invention.

Explanation of symbols

11 Electrophotographic photoreceptor (photoreceptor)
DESCRIPTION OF SYMBOLS 12 Charging member 13 Exposure means 14 Developing means 15 Toner 16 Transfer means 17 Cleaning means 18 Image receiving medium 19 Fixing means 1A Charge eliminating means 1D First transfer means 1E Second transfer means 1F Intermediate transfer belt 12a Charging member shaft 12b Charging 14Bk Black developing means 14C Cyan developing means 14M Magenta developing means 14Y Yellow developing means 30 Spacer member G Size of gap formed between charging member and electrophotographic photosensitive member

Claims (24)

At least an electrophotographic photosensitive member, a charging unit that uniformly charges the electrophotographic photosensitive member, an image exposure unit that forms an electrostatic latent image by performing image exposure after uniform charging, and a toner on the electrostatic latent image An image forming apparatus comprising: a developing unit for developing; a unit for transferring a developed image; and a cleaning unit for cleaning a transfer residual toner of the electrophotographic photosensitive member, wherein the charging member used in the charging unit is an electrophotographic photosensitive member The charging member is arranged to face and charge the electrophotographic photosensitive member in a non-contact manner by superimposing an alternating current voltage on a direct current voltage, and covering the shaft portion and the shaft portion. The main body is made of resin containing a conductive agent, and the size of the gap formed between the charging member and the electrophotographic photosensitive member is G (μm), and rotates around the central axis of the electrophotographic photosensitive member. Outer diameter runout When degrees were the A ([mu] m), the image forming apparatus G and A and satisfies the following relationship.
10 (μm) ≦ GA ≦ 90 (μm)   The image forming apparatus according to claim 1, wherein the size G of the gap satisfies a relationship of 20 (μm) ≦ G ≦ 100 (μm).   The image forming apparatus according to claim 1, wherein the outer diameter deflection accuracy A satisfies a relationship of 10 (μm) ≦ A ≦ 50 (μm).   The charging member includes a spacer member in a main body portion that is located outside an image forming region of the electrophotographic photosensitive member disposed to face the charging member, thereby forming a gap between the charging member and the electrophotographic photosensitive member. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein an AC voltage frequency supplied by the charging member to charge the electrophotographic photosensitive member is 100 Hz to 2.5 kHz.   6. The vibration amplitude (Vpp) of the AC voltage frequency supplied for charging the electrophotographic photosensitive member by the charging member is 1.0 to 3.0 kV. Image forming apparatus. The image forming apparatus according to claim 1, wherein the main body has a volume resistivity of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm.   The electrophotographic photosensitive member has a photosensitive layer, and has a charge transport layer as an outermost surface layer, and the thickness of the charge transport layer is 10 to 35 μm. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the electrophotographic photosensitive member includes a shaft having bearing members attached to openings at both ends and penetrating through the inside of the photosensitive member.   10. The electrophotographic photosensitive member operates in association with a charging member during operation, and the electrophotographic photosensitive member rotates at 200 rpm or less to be charged during application charging by the charging member. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the toner used in the developing unit contains inorganic fine particles having an average particle diameter of 70 to 300 nm. At least charging means for uniformly charging the electrophotographic photosensitive member, image exposing means for performing image exposure after uniform charging to form an electrostatic latent image, developing means for developing toner on the electrostatic latent image, development One or more means including a charging means of the transferred image transfer means and an electrophotographic photosensitive member, and a charging member used in the charging means is disposed so as to face the electrophotographic photosensitive member in a non-contact manner. The charging member superimposes an AC voltage on a DC voltage to apply and charge the electrophotographic photosensitive member in a non-contact manner, and is composed of a shaft portion and a body portion covering the shaft portion. G (μm) is the size of the gap formed between the charging member and the electrophotographic photosensitive member, and the outer diameter shake accuracy when rotated about the central axis of the electrophotographic photosensitive member is A. (Μm) that G and A satisfy the following relationship: A process cartridge that is detachable from an image forming apparatus.
10 (μm) ≦ GA ≦ 90 (μm)   The process cartridge according to claim 12, wherein the size G of the gap satisfies a relationship of 20 (μm) ≦ G ≦ 100 (μm).   14. The process cartridge according to claim 12, wherein the outer diameter deflection accuracy A satisfies a relationship of 10 (μm) ≦ A ≦ 50 (μm).   The charging member includes a spacer member in a main body portion that contacts an outside of an image forming area of the electrophotographic photosensitive member disposed to face the charging member, thereby forming a gap between the charging member and the electrophotographic photosensitive member. The process cartridge according to claim 12.   The process cartridge according to any one of claims 12 to 15, wherein an AC voltage frequency supplied by the charging member to charge the electrophotographic photosensitive member is 100 Hz to 2.5 kHz.   17. The vibration amplitude (Vpp) of the AC voltage frequency supplied for charging the electrophotographic photosensitive member by the charging member is 1.0 to 3.0 kV. Process cartridge. 18. The process cartridge according to claim 12, wherein the volume resistivity of the main body is 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm.   The electrophotographic photoreceptor has a photosensitive layer, a charge transport layer as an outermost surface layer, and the charge transport layer has a thickness of 10 to 35 μm. The described process cartridge.   The process cartridge according to any one of claims 12 to 19, wherein the electrophotographic photosensitive member includes a shaft having bearing members attached to openings at both ends and penetrating through the inside of the photosensitive member.   21. The electrophotographic photosensitive member operates in association with a charging member during operation, and the electrophotographic photosensitive member rotates at 200 rpm or less to be charged when applied by the charging member. The described process cartridge.   The process cartridge according to any one of claims 12 to 21, wherein the toner used in the developing unit contains inorganic fine particles having an average particle diameter of 70 to 300 nm.   An image forming apparatus comprising a plurality of process cartridges according to any one of claims 12 to 22. An image forming apparatus comprising an intermediate transfer unit that primarily transfers a toner image developed on the electrophotographic photosensitive member onto an intermediate transfer member and then secondary-transfers the toner image on the intermediate transfer member onto a recording material. The image forming apparatus according to claim 1, wherein toner images of a plurality of colors can be collectively transferred onto a recording material at a time.

Images