JPH08339114A - Electrifying member, process cartridge equipped with that electrifying member and electrophotographic device - Google Patents

Abstract

PURPOSE: To obtain a contact electrifying member in which electrification faults due to local irregularity in the resistance of an elastic layer or a rough surface layer are hardly caused, by specifying the constitution of the electrifying member. CONSTITUTION: This electrifying member is disposed in contact with a material to be charged and is used to charge the material by applying a voltage. The electrifying member consists of a base body and a surface layer containing a metal layer and a seamless tube in this order. The surface layer 2A is made of a seamless tube, while the metal tube 2B is made of an insulating hard body 2Ca and a base body 2Cb. As for the metal layer, for example, a good conductive material such as aluminum, copper, iron or an alloy containing these metals is preferably used. The metal layer is preferably a metal tube having 0.1-1.5mm thickness, and especially, an aluminum tube is preferable because the aluminum tube has extremely good surface smoothness, uniform thickness, roundness and straightness which are sufficient for the purpose and the tube is available at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member which is placed in contact with a member to be charged and which charges the member by applying a voltage.

The present invention also relates to a process cartridge having the above charging member and an electrophotographic apparatus.

[0003]

2. Description of the Related Art In recent years, a contact charging type charging means has been adopted as a charging means used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus. Contact charging is
By applying a voltage to a charging member arranged in contact with the charged body, the charged body is charged to a predetermined polarity and potential, and the voltage of the power supply can be lowered. Occurrence can be reduced,
There are advantages such as a simple structure and cost reduction.

The voltage applied to the charging member may be a system in which only a DC voltage is applied (DC application system), but a peak that is at least twice the charging start voltage of the member to be charged when a DC voltage is applied to the contact charging member. A method (AC application method) of forming an oscillating electric field having an inter-voltage (an electric field whose voltage value periodically changes with time) between the contact charging member and the charged body to charge the surface of the charged body is more preferable. It is possible and effective to carry out uniform charging.

Further, the contact charging device is a roller type charging device in which the charging member is a roller-shaped member (charging roller) depending on the shape and form of the charging member brought into contact with the member to be charged (Japanese Patent Laid-Open No. 63-63)
No. 7380 and No. 56-91253), and a blade type charging device using a blade-shaped member (charging blade) (Japanese Patent Laid-Open Nos. 64-24264 and 56-194349).
(Japanese Patent Laid-Open Publication No. 64-24264) and brush-type chargers (charging brushes) that use a brush-like member (charging brush).

The charging roller is rotatably supported by a bearing, is pressed against the body to be charged with a predetermined pressure, and is driven to rotate as the body to be charged moves.

The charging roller usually has a multi-layered structure including a cored bar centrally provided as a substrate, a conductive elastic layer provided in a roller shape around the cored bar, and a surface layer provided on the outer periphery of the cored bar. It is the body.

Of the above layers, the core metal is a rigid body for maintaining the shape of the roller, and also has a role as a power supply electrode layer.

The elastic layer is usually 10 ⁴ to 10 ⁹
Since it is required to have a volume specific resistance of Ω · cm and to have a function of ensuring uniform contact with an object to be charged by elastic deformation, rubber hardness (J
ISA) A vulcanized rubber having a flexibility of 70 degrees or less is used. The conventional charging roller includes a foaming type using a rubber foam (or a sponge-like rubber) as an elastic layer and a solid type not using a rubber foam.

Further, the surface layer improves the charging uniformity of the member to be charged, prevents the occurrence of leakage due to pinholes on the surface of the member to be charged, and prevents sticking of toner particles and paper powder. It also has a function of preventing bleeding of a softening agent such as oil or a plasticizer used for reducing the hardness of the elastic layer. The volume resistivity of the surface layer is usually 10 ⁵ to 10 ¹³ Ω · cm.
It was formed by applying a conductive paint or covering it with a seamless tube.

[0011]

However, in the case of the foaming type charging roller, it is difficult to make the size and distribution of the bubbles uniform, and in both the foaming type and the solid type, Due to reasons such as difficulty in making the degree of sulfurization uniform, local nonuniformity of the resistance value of the elastic layer is likely to occur, which may cause charging failure.

Further, in the case of the foaming type charging roller, since the skin layer formed on the surface of the elastic layer at the time of vulcanization has poor smoothness, it is necessary to remove the skin layer by a polishing treatment, but the bubble diameter can be made uniform. Since it is difficult, when large bubbles are exposed on the surface by polishing, dents are generated in the surface layer applied in the next step. If a charging roller having a dent in the surface layer is used, a charging failure occurs and a good image cannot be obtained.

An object of the present invention is to provide a contact charging member which is less likely to cause charging failure due to local unevenness of the resistance value of the elastic layer and unevenness of the surface layer.

Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the above charging member.

[0015]

That is, the present invention relates to a charging member which is disposed in contact with a member to be charged and which charges the member by applying a voltage, wherein the charging member is a substrate,
A charging member having a surface layer containing a metal layer and a seamless tube in this order.

The present invention also provides a process cartridge and an electrophotographic apparatus having the above charging member.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate in the present invention may also serve as a power feeding electrode layer, and its shape and material are not particularly limited, but it is usually a core metal of a roller. As the material of the substrate, any material having high rigidity and good conductivity such as stainless steel, aluminum or its alloy, copper or its alloy, iron or its alloy, and conductive engineering plastic can be used.

As the metal layer in the present invention, a good conductor such as aluminum, copper, iron, or an alloy containing these is preferably used, so that the resistance value of the elastic layer, which is a problem in the prior art, is locally nonuniform. Not only is it possible to prevent charging failure due to uneven charging, but also it has more excellent surface uniformity as compared with the conductive material-dispersed resin layer. From this point, the metal layer used in the present invention is preferably a metal tube having a thickness of 0.1 to 1.5 mm. Above all, it is preferable to use an aluminum tube which has extremely good surface smoothness, is sufficiently satisfactory in terms of wall thickness uniformity, roundness and straightness, and is inexpensive.

In addition to the cost, the metal layer used in the present invention is preferably a metal foil having a thickness of 5 to 100 μm in consideration of the contact property with the member to be charged and the charging sound.

Next, the surface layer used in the present invention will be described. The surface layer in the present invention is a polymer formed in advance in the form of a seamless tube, and is used by being externally fitted and closely attached to the metal layer.

Preferred polymers for use in the seamless tube of the present invention include silicone rubber and ethylene-
Propylene rubber, fluorine rubber, urethane rubber, epichlorohydrin rubber, acrylic rubber, natural rubber, isoprene rubber, putadiene rubber, 1,2-polybutadiene, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, chlorosulfonated polyethylene, polysulfide rubber And rubber such as chlorinated polyethylene; styrene-based, olefin-based, ester-based, urethane-based, isoprene-based, 1,2-butadiene-based, vinyl chloride-based, amide-based, and ionomer-based thermoplastic elastomers;
Polyethylene, various ethylene-based copolymers, polypropylene, propylene / ethylene copolymers and polyolefins such as polybutene, nylon 6, nylon 66, nylon 11, nylon 12 and other copolymerized polyamides such as nylon, polyethylene terephthalate (PE
T), saturated polyesters such as polybutylene terephthalate (PBT); polythretin, high-impact polystyrene (HIPS), acrylonitrile-butadiene-
Styrene resins such as styrene resin (ABS) and acrylonitrile-ethylene / propylene rubber-styrene resin (AES) and acrylonitrile-acrylic rubber-styrene resin (AAS); and acrylic resin, vinyl chloride resin, vinylidene chloride resin, polycarbonate, polyacetal , Polyphenylene oxide or polystyrene modified products thereof, polyimide resins, thermoplastic resins such as polyarylate and vinylidene fluoride homopolymers and copolymers, and the like.

Furthermore, a polymer alloy or polymer blend composed of two or more polymers selected from the above rubber, thermoplastic elastomer and thermoplastic resin can also be used.

The seamless tube of the present invention comprises a conductive polymer composition comprising the above various polymers and the following conductivity-imparting agent and, if necessary, other additives, extrusion molding method, injection molding method, blow molding method and the like. Can be obtained by forming a film in a tube shape. Of the various molding methods described above, the extrusion molding method is particularly suitable.

As the conductivity-imparting agent, known materials can be used, for example, carbon fine particles such as carbon black and graphite; metal fine particles such as nickel, silver, aluminum and copper; tin oxide, zinc oxide, titanium oxide, Conductive metal oxide fine particles containing aluminum oxide and silica as main components and doped with impurity ions having different valences; conductive fibers such as carbon fibers; metal fibers such as stainless fibers; carbon whiskers and potassium titanate whiskers Examples thereof include conductive whiskers such as conductive potassium titanate whiskers whose surface is subjected to a conductive treatment with metal oxide or carbon; and conductive polymer fine particles such as polyaniline and polypyrrole.

The seamless tube used in the present invention can be used by simply forming it by the above-mentioned various molding methods, but it is obtained by the above-mentioned various molding methods for the purpose of obtaining more excellent durability and environmental resistance. It is preferable to further crosslink the seamless tube to obtain a conductive crosslinked polymer. As a method of cross-linking the conductive polymer formed into a tube, sulfur depending on the type of the polymer,
A chemical cross-linking method in which a cross-linking agent such as an organic peroxide and amines is added in advance and cross-linking is generated at high temperature,
A radiation cross-linking method of cross-linking by irradiating radiation such as electron beam or γ-ray is effective. Among the above-mentioned various crosslinking methods, the electron beam crosslinking method is particularly preferable in that there is no risk of contamination of the charged body due to migration of the crosslinking agent or its decomposition product, further that high temperature treatment is not required and safety.

The resistance value of the surface layer used in the present invention is 1
It is preferably 0 ⁵ to 10 ¹³ Ω · cm, and particularly 1
It is preferably from 0 ⁶ to 10 ¹² Ω · cm.

In the present invention, by using the seamless tube as the surface layer, even if there is some unevenness on the metal layer, it is difficult for the unevenness to appear as unevenness on the surface layer, and extremely excellent charging uniformity is achieved. I was able to.

Further, in the present invention, since the metal layer, which is a good conductor, is used, it is considered that it occurs during molding.
It is possible to solve the technical problem peculiar to the tube layer, in particular, the non-uniformity of the resistance in the circumferential direction, and it is possible to obtain a charging member having an extremely uniform resistance value.

The surface layer used in the present invention can be formed into a film by various methods, but the extrusion method is preferable as described above. That is, a polymer and a conductivity-imparting agent and, if necessary, a compound in which a cross-linking agent, a stabilizer and other additives are mixed are manufactured, and the compound is extruded from a die having a ring-shaped slit by an extruder and cooled. By doing so, a seamless tube can be continuously manufactured. A heat-shrinkable tube can be obtained by expanding the tube diameter during cooling or by reheating after cooling and using a means such as air pressurization, and a non-heat-shrinkable tube without expansion treatment.

The seamless tube used in the present invention may be either a non-heat-shrinkable machine or a heat-shrinkable machine, but the method of external fitting differs depending on which one.

In the case of a non-heat-shrinkable tube, the inner diameter of the tube needs to be equal to or smaller than the outer diameter of the metal layer in order to secure the adhesion between the metal layer and the surface layer. The outer fitting process is completed by inserting a metal tube or a roller body having a metal layer in a state where the tube diameter is expanded by blowing compressed air and releasing the air pressure.

On the other hand, in the case of a heat-shrinkable tube, the inner diameter of the tube is preferably larger than the outer diameter of the metal layer. After inserting the metal tube or the roller body, the metal layer is heated in a constant temperature bath for a predetermined time. External fitting is performed by heat-shrinking the tube so as to be in close contact with.

In the present invention, it is preferable that the charging member has a supporting layer such as an elastic layer between the substrate and the metal layer.

In the prior art, it was essential that the elastic layer be a conductive elastic body that has a uniform resistance to a certain level. However, the support layer in the present invention is used in place of the conductive elastic layer used in the above-mentioned prior art, may be an insulator, and is formed uniformly in the entire length direction of the charging device. Does not necessarily need to be.

Further, the support layer in the present invention may be an elastic body having flexibility, or a hard body (or a rigid body having little flexibility) such as an insulating or conductive hard plastic. This is because, as described above, the main reason why the elastic layer is used in the prior art is to ensure a uniform contact with the body to be charged, and aluminum having sufficient roundness and straightness in the present invention. This is because when a tube or the like is used as the metal layer, even if the support layer is formed of a hard body having low flexibility, uniform contact with the charged body can be ensured.

That is, if the means for electrically connecting the power feeding electrode and the metal layer is prepared in some form, the function of the support layer may be only to support the metal layer.

Needless to say, in the present invention, it is also possible to use an elastic body having two functions of elasticity and electroconductivity used in the prior art.

In the present invention, as a means for electrically connecting the power supply electrode and the metal layer, for example, a metal spring or foil, a conductive polymer or its foam, a conductive paint or a conductive adhesive, etc. may be used. Can be used.

The specific constitution of the present invention will be described below with reference to FIGS. 1 to 4, but the present invention is not limited thereto.

In FIG. 1, 2A is a surface layer,
Seamless tubes are used. 2B is a metal tube, and 2Ca is an insulating hard body. 2Cb is a base, a cored bar, and an electrical conduction means between 2D, which is a power feeding electrode, and the metal tube 2B. A conductive rubber foam is assumed as the conducting means, but a metal spring or the like may be used. Support layer 2 with 2Ca and 2Cb combined
I will call it C.

In FIG. 2, the support layer 2C has elasticity and conductivity at the same time, and a conductive elastic body is used. In this case, since the metal layer 2B is present, there is no problem even if the resistance of the support layer 2C has local nonuniformity.

In FIG. 3, a metal foil is used as the metal layer 2B, 2Ca is an insulating elastic body, and 2Cb.
Is a conductive paint, is a base, is a core metal, and is an electrical conduction means between the power supply electrode 2D and the metal layer 2B.
2Ca and 2Cb are collectively referred to as a support layer 2C. Since the charging roller shown in FIG. 3 uses an insulating rubber as 2Ca, it is not necessary to control the resistance value in manufacturing, and a general-purpose rubber tube can be used. Therefore,
Manufacturing costs can be reduced. Further, the variation of the resistance value due to the change of the environment can be ignored, and it becomes possible to manufacture the charging roller of stable quality.

In FIG. 4, the core metal 2D is shortened and attached only to both ends. In addition, the conductive paint 2Cb is used as the electrical conduction means. This structure is easier to assemble than the structure of FIG. 1, and the manufacturing cost can be reduced.

FIG. 5 shows a schematic structure of an electrophotographic apparatus having a process cartridge having the charging member of the present invention.

In the figure, 1 is an electrophotographic photoreceptor,
It is rotationally driven in the arrow direction at a predetermined peripheral speed. Photoconductor 1
In the rotation process, the peripheral surface thereof is uniformly charged with a predetermined positive or negative potential by the charging member 2 of the present invention, and then an image from an image exposing means (not shown) such as slit exposure or laser beam scanning exposure. Receive exposure light 3. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoconductor 1.

The formed electrostatic latent image is then developed by the developing means 4.
The toner-developed image is developed by the toner, and the developed toner-developed image is transferred between the photoconductor 1 and the transfer unit 5 on a transfer material 6 fed in synchronism with the rotation of the photoconductor 1 from a paper feed unit (not shown). The images are sequentially transferred by the transfer means 5.

The transfer material 6 that has received the image transfer is separated from the surface of the photoconductor and is introduced into the image fixing means 7 to undergo image fixing and is printed out to the outside of the apparatus as a copy.

The surface of the photoconductor 1 after the image transfer is cleaned by the cleaning means 8 after the transfer residual toner is removed, and is repeatedly used for image formation.

In the present invention, among the above-mentioned electrophotographic photosensitive member 1, charging member 2, developing means 4, cleaning means 8 and the like, a plurality of components are integrally combined to form a process cartridge. The process cartridge may be detachably attached to the main body of the electrophotographic apparatus such as a copying machine or a laser beam printer. For example, the developing unit 4 and the cleaning unit 8 are integrally supported together with the photoconductor 1 and the charging member 2 to form a cartridge,
A guide means such as a rail 10 of the apparatus body can be used to form the process cartridge 9 which can be attached to and detached from the apparatus body.

Further, when the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is reflected light or transmitted light from an original, or the original is read by a sensor, converted into a signal, and the image exposure is performed according to this signal. Laser beam scanning,
It is the light emitted by driving the LED array and driving the liquid crystal shutter array.

[0051]

The present invention will be described in more detail with reference to the following examples. (Embodiment 1) This embodiment relates to the charging roller shown in FIG.

Outer diameter 12 mm, inner diameter 10 mm, length 225
mm heat pipe (made by Showa Aluminum Co., Ltd.) with an inner diameter of 16.5 mm and a wall thickness of 250 μm (Sumitomo Electric Co., Ltd., Sumitube G3), and heat-shrinked for 10 minutes in a constant temperature bath at 200 ° C. in an air atmosphere. As a result, a surface layer that was in close contact with the aluminum tube was formed.

The heat-shrinkable tube is formed by forming a film of conductive chlorinated polyethylene by an extrusion method, crosslinking it by electron beam irradiation, softening it by heating, expanding the tube diameter by air pressure, and cooling it to make it heat-shrinkable. It is a seamless tube provided. The resistance of the above tube after contraction is 1 × 1
Was 0 ⁸ Ω · cm.

Next, a core metal having a diameter of 6 mm and a length of 251 mm has a thickness of 3 mm, a width of 8 mm and a length of 100 at the center in the longitudinal direction.
Conductive urethane foam (BS
Tokai Kasei Co., Ltd., Everlite EPT-51) was spirally wound, and both ends were fixed to the core metal with adhesive tape, so that an electrical conduction path was formed between the aluminum tube and the core metal. The resistance value of the conductive urethane foam was 1 × 10 ⁵ Ω · cm.

The core metal is inserted into the aluminum tube having the above-mentioned surface layer, and a hard ring made of insulating nylon 6 having a length of 10 mm, an outer diameter of 10 mm and an inner diameter of 6 mm is pushed from both ends of the core metal, and an epoxy resin is used. After applying the adhesive,
The aluminum tube and the core metal were fixed in the arrangement as shown in FIG.

The local resistance value of the charging roller was measured by the following method. That is, as shown in FIG.
An aluminum foil 11 having a width of 10 mm was wound on the top, a direct current of 250 V was applied between the core metal and the aluminum foil from the power source 13, and the current flowing at that time was measured to calculate the resistance value between the core metal and the aluminum foil. And by moving the position of the aluminum foil,
The local variation of the resistance value of the charging roller in the longitudinal direction was measured. The local resistance value of the charging roller thus measured was (5.0 ± 0.05) × 10 ⁴ Ω, and it was found that the uniformity was extremely high.

Further, the irregularities on the surface of the charging roller were visually observed, but the irregularities were not seen as a problem.

Next, the charging roller is mounted on a cartridge (Canon, EP-L), and the cartridge is mounted on a laser beam printer (Canon, Laser S).
The image quality of the output image was visually evaluated by mounting on a hot A404). As a result, no abnormality was recognized even when 3500 images were output under the environment of 25 ° C. and 50% RH.

(Embodiment 2) This embodiment relates to the charging roller shown in FIG.

EPDM (Mitsui Petrochemical Co., EPT40
45) 100 parts by weight (hereinafter referred to as "part"), Zinc Hua No. 1 10
Parts, stearic acid 2 parts, accelerator M2 parts, accelerator BZ1
Part, sulfur 2 parts, foaming agent (Sankyo Kasei Co., Celmic C) 5 parts, foaming aid (Sankyo Kasei Co., Celton NP) 5
Parts, 20 parts of FEF carbon, 70 parts of insulating oil, and 8 parts of Ketjen Black EC were mixed and uniformly kneaded using a two-roll to obtain a conductive rubber compound.

A primer was attached to a cored bar having the same shape as in Example 1, the above rubber compound was wrapped around, and placed in a mold.
A rubber compound layer having a thickness of 1 mm was formed on the core metal by preforming at 40 ° C. and 100 kg / cm ² . This was inserted into an aluminum tube having the same shape as in Example 1, heated by steam heating (160 ° C., 30 minutes) for foaming and vulcanization, and the aluminum tube and the rubber layer were brought into close contact with each other. The roller body thus obtained was covered with the same heat-shrinkable tube as that used in Example 1, and heat-shrinked under the same conditions as in Example 1 to complete the charging roller.

When the local resistance value of the charging roller was measured by the same method as in Example 1, it was (5.2 ± 0.03).
It was × 10 ⁴ Ω, and it was found that the uniformity was extremely high. No unevenness on the charging roller surface was observed.

Further, the image quality of the output image was evaluated by the same method as in Example 1, but no abnormality was recognized even after outputting 3,500 images.

(Embodiment 3) This embodiment relates to the charging roller shown in FIG.

A commercially available natural rubber tube (inner diameter 6 mm × outer diameter 12 mm) was cut into a length of 225 mm, and the same core metal as that used in Example 1 was inserted into a rubber roller. next,
An aluminum foil with a thickness of 20 μm is evenly wound around the entire rubber part, and one end is coated with a synthetic rubber conductive adhesive (manufactured by ThreeBond Co., 3315) to form an electrical conduction path between the aluminum foil and the core metal. did.

The roller body thus obtained was covered with a heat-shrinkable tube similar to that in Example 1, and heat-shrinked under the same conditions as in Example 1.

When the local resistance value was measured by the same method as in Example 1, it was (5.8 ± 0.06) × 10 ⁴ Ω, and it was found that the uniformity was extremely high. No irregularities on the surface of the charging roller were observed.

The image quality of the output image was evaluated in the same manner as in Example 1, but no abnormalities were recognized even after outputting 3,500 images.

(Embodiment 4) This embodiment relates to the charging roller shown in FIG.

Except that a core bar having a length of 50 mm was attached to both ends so that the total length was 251 mm, and that a conductive path was formed by applying the conductive adhesive used in Example 3 to one end. A charging roller was completed in the same manner as in Example 1.

The variation in local resistance value, the surface irregularities, and the image quality of the output image were evaluated by the same method as in Example 1, and similar results were obtained.

Example 5 A thickness of 20 was used instead of the aluminum foil.
A charging roller was prepared and evaluated in the same manner as in Example 3 except that the iron foil of μm was used. The results of resistance value measurement and image quality evaluation were the same as in Example 3.

Example 6 A thickness of 20 was used instead of the aluminum foil.
A charging roller was prepared and evaluated in the same manner as in Example 3 except that a stainless foil of μm was used. The results of resistance value measurement and image quality evaluation were the same as in Example 3.

(Comparative Example 1) A roller body was prepared in the same manner as in Example 1 except that the heat-shrinkable tube (Sumitube G3 manufactured by Sumitomo Electric Industries, Ltd.) was not covered. The roller body is the same as the one without the surface layer 2A in FIG.

Next, a dispersion solution consisting of 75 g of methoxymethylated nylon (made by Teikoku Chemical Industry Co., Ltd., Toresin EF30T), 315 g of methanol, 110 g of toluene, 1.5 g of citric acid, and 1.5 g of carbon black (Ketjenblack EC). Prepared, soak the roller body in this,
By repeating the operation of drying at 70 ° C. for 15 minutes twice, the surface layer 2A was formed and used as the charging roller. The surface layer 2A had a thickness of 30 μm.

When the local variation of the resistance value was measured by the same method as in Example 1, it was (4.3 ± 0.05) × 10 ⁴ Ω.
And was equivalent to Example 1. The results of visually observing the irregularities were also the same.

Further, when the image quality was evaluated in the same manner as in Example 1, the above was confirmed after the output of 2000 images. When the cartridge was disassembled and the roller was removed and observed, the toner adhesion state on the roller surface was inhomogeneous, and there was a portion that was not in contact with the photoconductor, and the toner adhered thickly to that portion, and an image or more occurred. It turned out that I did. It was presumed that this was caused by the fact that the surface layer created in this comparative example was thin and hard, so that a sufficient nip could not be taken.

(Comparative Example 2) The aluminum tube was removed from the roller body obtained in the same manner as in Example 2 to obtain a roller body composed of only a core metal and a rubber layer.

A heat-shrinkable tube similar to that used in Example 1 was placed on the roller body, and heat-shrinked under the same conditions as in Example 1 to complete the charging roller.

When the local variation of the resistance value was measured by the same method as in Example 1, it was (25.5 ± 11.2) × 10 ^4.
It was found that the fluctuation was large. No unevenness on the surface of the charging roller was observed.

Further, when the image quality was evaluated in the same manner as in Example 1, image abnormalities occurred from 2500 sheets. A close examination of the situation revealed that fogging occurred corresponding to the high resistance portion of the charging roller.

[0082]

As described above, the contact charging device according to the present invention has excellent characteristics such as a small local nonuniform resistance value and a good surface smoothness.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a contact charging member of Example 1.

FIG. 2 is a schematic vertical sectional view of a contact charging member of Example 2.

FIG. 3 is a schematic vertical sectional view of a contact charging member of Example 3.

FIG. 4 is a schematic vertical sectional view of a contact charging member of Example 4.

FIG. 5 is a schematic configuration diagram of an electrophotographic apparatus having a process cartridge having the contact charging member of the present invention.

FIG. 6 is a diagram showing how to measure the local resistance of the charging roller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Yamashita 1888-2 Kukizaki, Kukizaki-cho, Inashiki-gun, Ibaraki Canon Inc.

Claims (22)

[Claims] 1. A charging member, which is placed in contact with a member to be charged and charges the member by applying a voltage, wherein the charging member comprises a substrate, a surface layer containing a metal layer and a seamless tube in this order. A charging member having. 2. The charging member according to claim 1, wherein the charging member has a support layer between the substrate and the metal layer. 3. The method according to claim 1, wherein the metal layer is a metal tube.
The charging member described. 4. The metal tube is an aluminum tube.
The charging member described. 5. The method according to claim 1, wherein the metal layer is a metal foil.
The charging member described. 6. The charging member according to claim 5, wherein the metal foil is an aluminum foil. 7. The charging member according to claim 1, wherein the charging member has a roller shape. 8. The charging member according to claim 1, wherein the member to be charged is an electrophotographic photosensitive member. 9. A process cartridge having an electrophotographic photosensitive member and a charging member, or an electrophotographic photosensitive member, a charging member and a developing unit or a cleaning unit, wherein the charging member is disposed in contact with the electrophotographic photosensitive member and a voltage is applied. The electrophotographic photosensitive member is charged by being subjected to the above, and has a substrate, a metal layer, and a surface layer containing a seamless tube in this order. A process cartridge, which integrally supports a cleaning unit or a cleaning unit, and is detachable from the main body of the electrophotographic apparatus. 10. The process cartridge according to claim 9, wherein the charging member has a support layer between the substrate and the metal layer. 11. The charging member according to claim 9, wherein the metal layer is a metal tube. 12. The process cartridge according to claim 11, wherein the metal tube is an aluminum tube. 13. The process cartridge according to claim 9, wherein the metal layer is a metal foil. 14. The process cartridge according to claim 13, wherein the metal foil is an aluminum foil. 15. The process cartridge according to claim 9, wherein the charging member has a roller shape. 16. An electrophotographic apparatus having an electrophotographic photosensitive member, a charging member, an exposing unit, a developing unit and a transferring unit, wherein the charging member is placed in contact with the electrophotographic photosensitive member, and a voltage is applied to the electrophotographic photosensitive member. An electrophotographic apparatus comprising an electrophotographic photosensitive member charged and having a substrate, a metal layer and a surface layer containing a seamless tube in this order. 17. The electrophotographic apparatus according to claim 16, wherein the charging member has a support layer between the substrate and the metal layer. 18. The electrophotographic apparatus according to claim 16, wherein the metal layer is a metal tube. 19. The electrophotographic apparatus according to claim 18, wherein the metal tube is an aluminum tube. 20. The electrophotographic apparatus according to claim 16, wherein the metal layer is a metal foil. 21. The electrophotographic apparatus according to claim 20, wherein the metal foil is an aluminum foil. 22. The charging member is roller-shaped.
22. The electrophotographic apparatus according to any one of 21 to 21.