JPH05281773A - Image carrier drum, image forming device and process cartridge - Google Patents

Abstract

PURPOSE:To prevent or reduce a generated electrification sound by inserting a gas cell structure consisting of an assembled body of the subdivided gas cells into an image carrier drum and imparting an vibration proof function in the image carrier drum. CONSTITUTION:The gas cell assembled structure 1c which is inserted into the image carried drum 1c uses a packing buffer material which is formed many independent air cells 1f between the materials which are formed of two soft plastic sheets 1d, 1e, and the material is wound up to make a roll and is inserted and arranged in the photosensitive drum 1. Even in the case that the image carrier drum 1 is performed an electrification treatment by an AC impression system by inserting and arranging the gas cell assembled structure 1c consisting of the assembly the subdivided gas cells in the image carrier drum 1 or by arranging while a gas cell assembled structure layer consisting of the assembly of subdivided gas cells is pressed by a pressure means to an inside wall surface of the image carrier drum 1 and is adhered closely with each other, the generating electrification sound (noise) be restrained to such a degree that does not practically pose any problems.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier drum, an image forming apparatus, and a process cartridge.

[0002]

2. Description of the Related Art Electrophotographic devices (copiers, printers, etc.)
In an image forming apparatus such as an electrostatic recording device, an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric is charged (including static elimination)
A corona discharger, which is a non-contact type charging means, has been mainly used as a means.

Although the corona discharger has an advantage of being uniformly charged, it requires an expensive high voltage power source, requires a space such as itself and a shield space for the high voltage power source, and generates corona products such as ozone. However, there is a problem that an additional means / mechanism is required to deal with the problem, which is a factor for increasing the size and cost of the device.

Therefore, recently, instead of the corona discharger having many problems as described above, a contact type charging means is being adopted. The contact charging is to charge the surface of the body to be charged to a predetermined polarity and potential by bringing a charging member (conductive member) to which a voltage is applied into contact with the body to be charged, which can lower the power supply and generate corona such as ozone. There are advantages such as less material generation, simple structure, and cost reduction.

A roller charging type using a roller body as a contact charging member (JP-A-56-91253) and a blade charging type using a blade body (JP-A-56-194349).
JP-A-56-1), a charging / cleaning combined type (JP-A-56-1).
No. 65166) has been devised.

The voltage applied to the charging member may be only a DC voltage (DC application method), but an oscillating voltage, for example, a superimposed voltage of a DC voltage component and an alternating voltage component, preferably, the applicant of the present invention has previously proposed (Japanese Patent Laid-Open Publication No. Sho. 63-149669, etc.), the DC voltage component (DC voltage having a potential corresponding to the target charging potential) and twice or more the charging start voltage of the member to be charged when the DC voltage is applied to the contact charging member. The method (AC application method) of applying the superimposed voltage of the alternating voltage (the voltage whose voltage value changes periodically with time) having the peak-to-peak voltage (V _PP ; PEAK TO PEAK) ,
It is possible and effective to carry out uniform charging treatment.

The oscillating voltage is an alternating voltage component (AC component) or a superimposed voltage of an AC component and a DC voltage component (DC component), and the waveform of the AC component may be a sine wave, a rectangular wave, a triangular wave or the like. It may be a rectangular wave voltage formed by periodically turning on and off a DC power supply.

FIG. 6 shows a schematic structure of an example of an image forming apparatus which employs the above-mentioned AC application type contact charging means as the charging means of the image carrier. The image forming apparatus of this example is a copying machine or a laser printer using an electrophotographic process.

Reference numeral 10 denotes a photosensitive drum as an image bearing drum, which is rotationally driven in a clockwise direction indicated by an arrow A at a predetermined peripheral speed. Reference numeral 12 is a conductive drum base as a base layer of the image bearing drum, for example, a grounded aluminum drum. Reference numeral 11 is a photosensitive layer formed on the outer peripheral surface of the drum substrate.

Reference numeral 2 is a charging roller as a contact charging member. The charging roller 2 of this example is made of a metal cored bar 21, a low resistance layer 22 such as a conductive rubber formed concentrically on the outer circumference of the cored bar, and a nylon formed on the outside thereof such as resin. The high resistance layer 23 is provided.

The charging roller 2 is arranged substantially parallel to the photosensitive drum 1 so that both ends of the cored bar 21 are held by bearing members (not shown), and a pressing spring 24 presses and urges the photosensitive drum 1 toward the photosensitive drum 1. It is pressed against the photosensitive drum 1 surface with a predetermined pressing force,
In the case of this example, the photosensitive drum 1 is driven to rotate as it rotates.

The charging roller 2 is supplied from the power source 3 to the mandrel 2
An AC component having a peak-to-peak voltage that is at least twice the charging start voltage of the photoconductor, via the sliding electrode 25 that is in contact with 1.
An oscillating voltage (V _ac + V _dc ) superposed with a DC component of a potential corresponding to the target charging potential is applied. As a result, the peripheral surface of the rotary photosensitive drum 1 is uniformly contact-charged by the AC application method.

Next, the charged surface of the rotary photosensitive drum 10 is subjected to image exposure 4 by image information exposure means (an analog exposure means for original image, a digital scanning exposure means for image information, etc.) not shown. An electrostatic latent image corresponding to the image information is formed.

The latent image is visualized (developed) as a toner image by the developing sleeve 5 of the developing device, and the toner image is
The recording material (transfer material) 7 is sequentially transferred from a paper feeding portion (not shown) to a pressure contact nip portion (transfer portion) between the photosensitive drum 10 and the transfer roller 6 at a predetermined timing.

The recording material 7 which has received the toner image transfer is separated from the surface of the photosensitive drum 10 and conveyed to a fixing means (not shown).
The toner image is fixed and output as an image formed product.

After the recording material is separated, the surface of the rotary photosensitive drum 10 is cleaned by a cleaning blade 8 of a cleaning device to remove residual adhered substances such as transfer residual toner, and is repeatedly used for image formation.

[0017]

By the way, as a problem of the AC charging type contact charging means, generation of a vibration sound called "charging sound" due to the AC component of the vibration voltage applied to the contact charging member can be mentioned.

The mechanism of generation of this charging sound will be described with reference to the model diagram of FIG.

.. Since the oscillating voltage (V _ac + V _dc ) is applied to the charging member (charging roller) 2, the AC component of the oscillating voltage causes the charging roller to sandwich the photosensitive layer 11 of the photosensitive drum 10 at a certain moment as shown in (a). Positive charges are induced on the second side and negative charges are induced on the base layer 12 side of the photosensitive drum 10.

[0020]. Since these positive and negative charges attract each other, the surface of the charging roller 2 is the photosensitive drum 1.
It is attracted to the 0 side against elasticity and moves from the position indicated by the solid line to the position indicated by the broken line as shown in (a) ((a) → (b)).

[0021]. Then, when the AC electric field starts reversing, the positive charge on the charging roller 2 side and the base layer 1 of the photosensitive drum 10
The negative charges on the 2 side start to be canceled by the charges of the opposite polarities that have respectively been induced.

When the AC electric field just changes from positive to negative, the positive charge on the charging roller 2 side and the negative charge on the base layer 12 side of the photosensitive drum 10 disappear.

.. As a result, the surface of the charging roller 2 is returned from the position indicated by the solid line to the position indicated by the broken line by the elastic return force by releasing the attractive force against the elasticity ((b) → (A)).

[0024]. Further, when the AC electric field goes toward a negative peak, as shown in (c), the charging roller 2
A negative charge is induced on the side, and a positive charge is induced on the base layer 12 side of the photosensitive drum 10. Therefore, the surface of the charging roller 2 is again attracted to the photosensitive drum 10 side against the elasticity by the attraction force of both the negative and positive charges, and moves from the solid line position to the broken line position ((b) → ( c)).

As described above, in response to repeated positive and negative reversals of the AC electric field, the surface of the charging roller 2 is attracted to the photosensitive drum 10 side against the elasticity and moved to a position, and the attraction force is released. It is conceivable that the charging roller 2 starts to vibrate with the application of the oscillating voltage and strikes the photosensitive drum 10 due to the repeated phenomenon of the return movement motion, and as a result, "charging sound" is generated.

Assuming that the frequency of the AC electric field (voltage) is f and the vibration frequency of the charging member 2 is F, the charging member 2 vibrates twice during one cycle of the AC voltage, as is clear from the above description. Therefore, there is the following relationship between both f and F.

2f (H _Z ) = F (c / s) The charging sound is not limited to the case where the contact charging member is the charging roller, but is generated by the charging blade, the charging pad or the like by the same mechanism.

As a measure for reducing the charging noise generated in the contact charging of the AC application system, the peak-to-peak voltage V _PP of the AC component of the oscillating voltage (V _ac + V _dc ) that is the charging bias applied to the contact charging member 2 is charged to the photosensitive drum 10. If the value is smaller than twice the starting voltage, the charging noise can be improved to a considerably low level.

However, in the AC charging type contact charging,
Lowering the peak-to-peak voltage V _PP of the AC component means A
A so-called "leveling effect" that allows uniform charging by applying C component
Therefore, uniform charging cannot be obtained on the photosensitive drum, and spot-like uneven charging occurs. This is because the contact surface between the charging member 2 and the photosensitive drum 1 is microscopically uneven, and an ideal contact surface cannot be obtained.

In the image forming process of electrophotography or electrostatic recording, the spot-shaped uneven charging state of the photosensitive drum 10, which is a member to be charged, causes spot-shaped black spot image unevenness corresponding to the spot-shaped uneven charging in the output image. As a result, high quality images cannot be obtained.

Although a charging noise preventing method has been proposed in which an anti-vibration member made of rubber or the like is placed in the photosensitive drum 10, there are problems in that the photosensitive drum 10 is deformed, weighs, and the manufacturing cost is high. is not.

The present invention also aims to prevent or reduce the charging noise generated by inserting an anti-vibration member into the image carrier drum, but it involves the problems of drum deformation, weight increase and high manufacturing cost. An image carrier drum, an image forming apparatus, and a process cartridge are provided.

[0033]

SUMMARY OF THE INVENTION The present invention is an image carrier drum, an image forming apparatus, and a process cartridge characterized by the following configurations.

(1) An image carrier drum which is charged by abutting a charging member to which an oscillating voltage is applied, and is a gas cell assembly structure composed of a group of gas cells subdivided in the image carrier drum. An image carrier drum, wherein an object is inserted.

(2) An image carrier drum, which is charged by abutting of a charging member to which an oscillating voltage is applied, which is pressed into close contact with the inner wall surface of the image carrier drum by pressing means and is subdivided. An image carrier drum, wherein a gas cell assembly structure layer composed of a collection of gas cells is present.

(3) The vibration voltage applied to the charging member is
The image carrier drum according to (1) or (2), which is a superimposed voltage of a DC voltage component and an alternating voltage component.

(4) The vibration voltage applied to the charging member is
It is a superimposed voltage of a DC voltage component and an alternating voltage component having a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier drum when a DC voltage is applied to the charging member (1) or The image bearing drum according to (2).

(5) The image bearing drum is a drum in which a gas cell assembly structure consisting of a collection of subdivided gas cells is inserted, and the charging means of the drum applies an oscillating voltage. An image forming apparatus comprising contact-type charging means for bringing a charging member into contact with the drum.

(6) The image carrier drum has a gas cell assembly structure layer consisting of a collection of subdivided gas cells, which is pressed against the inner wall surface of the image carrier drum by a pressing means.
An image forming apparatus, wherein the charging means of the drum is a contact type charging means for bringing a charging member to which an oscillating voltage is applied into contact with the drum.

(7) The vibration voltage applied to the charging member is
The image forming apparatus according to (5) or (6), which is a superimposed voltage of a DC voltage component and an alternating voltage component.

(8) The vibration voltage applied to the charging member is
It is a superimposed voltage of a DC voltage component and an alternating voltage component having a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier drum when a DC voltage is applied to the charging member (5) or The image forming apparatus according to (6).

(9) An image carrier drum, and a process cartridge that includes at least one of charging means, developing means, and cleaning means for the drum and is attached to and detached from the main body of the image forming apparatus. A contact type in which a gas cell assembly structure comprising a collection of subdivided gas cells is inserted in the drum, and a charging means of the drum contacts a charging member to which an oscillating voltage is applied to the drum. A process cartridge characterized in that it is a charging means of.

(10) An image carrier drum, and a process cartridge including at least one of a charging unit, a developing unit, and a cleaning unit for the drum, which is attached to and detached from the main body of the image forming apparatus. And a gas cell assembly structure layer consisting of a collection of subdivided gas cells, which is pressed and adhered to the inner wall surface by a compression means, and the charging means of the drum applies a vibration voltage to the charging member. A process cartridge which is a contact type charging means for bringing the drum into contact with the drum.

(11) The process cartridge described in (9) or (10), wherein the vibration voltage applied to the charging member is a superimposed voltage of a DC voltage component and an alternating voltage component.

(12) The oscillating voltage applied to the charging member has a DC voltage component and an alternating voltage component having a peak-to-peak voltage which is more than twice the charging start voltage of the image carrier drum when the DC voltage is applied to the charging member. The process cartridge according to (9) or (10), which is a superimposed voltage of

[0046]

[Operation] A gas cell assembly consisting of a collection of subdivided gas cells is inserted and arranged in the image carrier drum, or a gas cell assembly consisting of a collection of subdivided gas cells on the inner wall surface of the image carrier drum. By arranging the structure layers so that they are pressed and brought into close contact with each other by the pressing means, the charging noise (noise) generated even when the image bearing drum is subjected to the charging process by the AC application method, as will be apparent from the actual measurement of the embodiment described later. ) Could be suppressed to such an extent that it does not pose a practical problem.

It is considered that this effect of suppressing the charging noise is due to the fact that the vibration of the air in the drum is suppressed by the gas cell assembly structure, which is arranged in the image carrier drum and is composed of a group of subdivided gas cells.

.. As the gas cell assembly structure including a collection of subdivided gas cells, for example, a cushioning material made of a soft plastic sheet (film) having a number of independent air cells formed therein can be used.

Since such a gas cell assembly structure is lightweight and can be obtained in large quantities at low cost, even if such a member is packed in the image carrier drum to suppress the charging noise, Deformation and weight increase of the drum are not a problem at all,
Moreover, the cost hardly increases.

As the gas cell assembly structure, it is also possible to use an independent pore or continuous pore low density plastic foam having a large expansion ratio, or a natural gas cell assembly structure such as sponge.

[0051]

【Example】

<Embodiment 1> (FIGS. 1 to 4) FIG. 1 is a partially cutaway perspective view of a photosensitive drum 1 in which a gas cell assembly structure 10 including a collection of subdivided gas cells is inserted and arranged in a drum ( FIG. 2 shows a cross-sectional model view.

The base layer (cylinder) 1b of the photosensitive drum 1 may be made of any material, but is generally aluminum.

As the photosensitive layer 1a, various known organic and inorganic photosensitive materials can be used, and the photosensitive material layer can be composed of two or more layers to form a composite layer. Also, other functional layers can be added. For example, an undercoat layer having a barrier function and an adhesive function may be provided between the metal base layer 1b of the drum and the photosensitive layer 1a, and the surface unevenness and defects of the drum base layer 1b may be covered between the metal base layer 1b and the undercoat layer of the drum. When the image input is laser light, it is possible to provide a conductive layer for the purpose of preventing interference fringes due to scattering.

In this embodiment, the gas cell assembly structure 1c inserted and arranged in the drum 1 is composed of two soft plastic sheets 1d, as shown in the sectional model view of the structure in FIG.
Using a commercially available cushioning material made of soft plastic sheet (commonly known as Airpack, Ube Industries, Sekisui Chemical, etc.) that has 1e as a material and has a number of independent air cells (air layers) 1f formed between them Then, this is wound and rolled and inserted and disposed in the photosensitive drum 1.

FIG. 4 is a schematic cross-sectional view of an example of the process cartridge 20 in which the photosensitive drum 1 is incorporated and used.

The cartridge 20 of this example is the photosensitive drum 1.
The contact charging roller 2, the developing device 21, and the cleaning device 22 can be attached to the image forming apparatus main body (not shown) at once by assembling them in the cartridge housing 23 in a predetermined arrangement relationship. It was done like this. Reference numeral 24 denotes a drum cover, which closes when the cartridge 20 is removed from the main body of the image forming apparatus to conceal and protect the externally exposed lower surface of the photosensitive drum 1.

When the cartridge 20 is mounted to the main body of the image forming apparatus in a predetermined manner, the drum cover 24 opens so that the lower surface of the photosensitive drum 1 faces the transfer roller 6 of the main body of the image forming apparatus. The exposure window cover 25 is also opened. Then, the mounted process cartridge 20 side and the image forming apparatus main body side are mechanically and electrically coupled to each other to be in an image forming operable state.

The contact charging member 2 is not limited to the roller type, but various known shapes and forms such as a blade type, a wire type and a brush type can be used.

As the image forming process means such as the developing device 21, the exposing means, the transferring means 6 and the cleaning device 22, various known ones can be used. The process cartridge 20 can be configured by including one or more desired process devices in addition to the photosensitive drum 1.

Measurement of Generated Noise (1) Preparation of Photosensitive Drum 1 Outer diameter 30 mm × as the photosensitive drum base layer (base) 1b
On the surface of an aluminum drum having a length of 260.5 mm, tin oxide coated titanium oxide; product name: Kronos ECT-62 (manufactured by Titanium Industry Co., Ltd.) phenol resin; product name: J-325 (manufactured by Dainippon Ink and Chemicals, Inc.) Apply the coating solution to the conductive layer (film thickness 20
μm) was formed.

Next, a subbing layer (film thickness: 1 μm) made of polyamide resin; trade name Amilan CM-8000 (manufactured by Toray Industries, Inc.) was provided.

Then, a disazo pigment having the following structural formula [Chemical formula 1] and a coating solution of polyvinyl butyral resin (trade name: S-REC BX-1 (manufactured by Sekisui Chemical Co., Ltd.)) are applied to form a charge generating layer. (Film thickness 0.15μ
m) is provided.

[0063]

[Chemical 1] Finally, 10 parts of a triarylamine compound represented by the following structural formula [Chemical Formula 2] and 10 parts of a styrene-methylmethacrynote copolymer resin (trade name: Estyrene MS-200 (manufactured by Nippon Steel Chemical Co., Ltd.) It was dissolved in a mixed solvent of 50 parts of benzene and 10 parts of dichloromethane to obtain a coating liquid for forming a charge transport layer.

[0064]

[Chemical 2] This coating liquid was applied onto the charge generation layer thus formed to form a charge transport layer (film thickness after drying 20 μm).

In this way, the photosensitive layer 1a (charge generation layer +
In the aluminum drum 1b on which the charge transport layer) is formed,
Each independent air cell 1f has a diameter Φ = 8 mm and a height L = 3.
A shock-absorbing material 1c (trade name: air cap # 40; manufactured by Kawakami Sangyo Co., Ltd.) made of a soft plastic sheet of mm was rolled and inserted into the photosensitive drum 1, and the photosensitive drum 1 was prepared.

(2) Process Cartridge 20 This photosensitive drum 1 was incorporated into an electrophotographic cartridge 20 (EP-S cartridge: manufactured by Canon Inc.) as shown in FIG. The contact charging member 2 was used by removing the charging roller incorporated in the Canon EP-L cartridge.

(3) Measurement of Noise Level This electrophotographic cartridge 20 is mounted on an actual machine (Laser Shot A408: manufactured by Canon Inc.), and the noise level generated by the machine at the time of image output is measured in front of the machine in an anechoic chamber. ·right side·
The measurement was performed at 1 m points on the left side surface, rear surface, and upper surface.

The charging bias applied to the contact charging roller 2 is a DC voltage component (DC component): -700 V, an alternating voltage component (AC component): V _PP = 1800 V, a frequency f = 400 H _Z, a superimposed voltage of a sine wave.

Further, the noise level was measured using an integral average type ordinary sound level meter (NL-02 type, manufactured by Rion Co.).
The measurement results are shown in [Table 1] below.

Example 2 (FIG. 5) The cushioning material 1c of the soft plastic sheet used in Example 1
Was used to prepare a cylindrical member 1g as a gas cell aggregate structure layer having an outer diameter substantially corresponding to the inner diameter of the photosensitive drum prepared in Example 1, and the cylindrical member 1g was prepared in Example 1 as a photosensitive member. A rubber tube 1h is inserted into the drum as a compression means, and the tube 1h is filled with air to form a cylindrical member (gas cell aggregate structure layer) 1g between the inner wall surface of the drum 1b and the rubber tube 1h. It was sandwiched between and held in a state of being pressed and closely attached to the inner wall surface of the drum.

FIG. 5 is a schematic cross-sectional view of the photosensitive drum 1.

Using this photosensitive drum 1, a process cartridge 20 was constructed in the same manner as in Example 1 and mounted on an actual machine to measure the generated noise level. The measurement results are shown in [Table 1].

Comparative Example The noise level generated when none of the photosensitive drums 1 was inserted was also measured. The measurement results are shown in [Table 1].

[0074]

[Table 1]

[0075]

As is apparent from [Table 1], according to the present invention, the generated noise is remarkably reduced. Further, compared to the conventional noise countermeasures, there are no adverse effects such as drum deformation and weight increase, and there is almost no increase in cost.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view (model diagram) of a photosensitive drum in which a gas cell assembly structure including a collection of subdivided gas cells is inserted and arranged in a drum.

[Figure 2] Cross-section model diagram

FIG. 3 is a schematic cross-sectional view of the structure of a gas cell assembly structure.

FIG. 4 is a cross-sectional model view of an example of a process cartridge incorporating the photosensitive drum of FIGS. 1 and 2.

FIG. 5 is a schematic cross-sectional view of a photosensitive drum of another embodiment.

FIG. 6 is a schematic configuration diagram of an example of an image forming apparatus using a contact charging device.

7 (a), (b), and (c) are explanatory views of a mechanism of generating a charging sound.

[Explanation of symbols]

 1.10. Photosensitive drum (image bearing drum) 1a.11 Photosensitive layer 1b.12 Drum substrate 1c.1g Gas cell assembly structure 1h Air-filled tube (pressing means) 2 Charging roller 3 Charging bias applying power source 5 Developing sleeve 6 Transfer Roller 8 Cleaning blade 20 Process cartridge

Front Page Continuation (72) Inventor Mitsuru Honda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. An image carrier drum, which is charged by abutting a charging member to which an oscillating voltage is applied, comprising a group of gas cells subdivided in the image carrier drum. An image carrier drum, wherein the image carrier drum is inserted. 2. An image carrier drum charged by contact of a charging member to which an oscillating voltage is applied, wherein the inner wall surface of the image carrier drum is pressed into close contact with a pressing means and is subdivided. An image carrier drum, characterized in that a gas cell assembly structure layer composed of gas cells is present. 3. The image carrier drum according to claim 1, wherein the oscillating voltage applied to the charging member is a superimposed voltage of a DC voltage component and an alternating voltage component. 4. The oscillating voltage applied to the charging member is composed of a DC voltage component and an alternating voltage component having a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier drum when the DC voltage is applied to the charging member. The image carrier drum according to claim 1 or 2, wherein the image carrier drum has a superimposed voltage. 5. An image bearing drum, wherein a gas cell assembly structure comprising a collection of subdivided gas cells is inserted into the drum, and the charging means of the drum is charged by applying an oscillating voltage. An image forming apparatus comprising contact-type charging means for bringing a member into contact with the drum. 6. An image carrier drum, wherein an inner wall surface of the drum is provided with a gas cell assembly structure layer composed of an assembly of subdivided gas cells, which is pressed and brought into close contact with a pressing means. An image forming apparatus, wherein the charging means is a contact type charging means for bringing a charging member, to which an oscillating voltage is applied, into contact with the drum. 7. The image forming apparatus according to claim 5, wherein the oscillating voltage applied to the charging member is a superimposed voltage of a DC voltage component and an alternating voltage component. 8. The oscillating voltage applied to the charging member is composed of a DC voltage component and an alternating voltage component having a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier drum when the DC voltage is applied to the charging member. The image forming apparatus according to claim 5, wherein the image forming apparatus has a superimposed voltage. 9. An image carrier drum, and a process cartridge that includes at least one of a charging unit, a developing unit, and a cleaning unit for the drum and is attached to and detached from the main body of the image forming apparatus. A gas cell assembly structure composed of a collection of subdivided gas cells is inserted in the drum, and a charging means of the drum in which a charging member to which an oscillating voltage is applied is brought into contact with the drum A process cartridge comprising a charging means. 10. An image carrier drum, and a process cartridge that includes at least one of a charging unit, a developing unit, and a cleaning unit for the drum and is attached to and detached from the main body of the image forming apparatus. There is a gas cell assembly structure layer composed of a collection of subdivided gas cells, which is pressed and adhered to the inner wall surface by a pressing means, and the charging means of the drum is a charging member to which an oscillating voltage is applied. A process cartridge characterized in that it is a contact type charging means that is brought into contact with the drum. 11. The process cartridge according to claim 9, wherein the oscillating voltage applied to the charging member is a superimposed voltage of a DC voltage component and an alternating voltage component. 12. The oscillating voltage applied to the charging member is composed of a DC voltage component and an alternating voltage component having a peak-to-peak voltage that is at least twice the charging start voltage of the image carrier drum when the DC voltage is applied to the charging member. The process cartridge according to claim 9 or 10, wherein the process cartridge has a superimposed voltage.