JP2661418B2 - Charging device and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and a charging method. In particular, the present invention relates to a contact charging device and a method for charging a latent image holding member of an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, as a charging device for a latent image holding member used in an electrophotographic apparatus such as a plain paper copier or a laser printer, an LED printer, a liquid crystal printer, etc., a corona discharge device is generally used and widely used. Have been done. However, the corona discharge device has the following problems. 1) A high voltage power supply is required to generate electric discharge
V or more is required. Therefore, the cost of the power supply increases,
Since a high-voltage cable is required for wiring and the like, and an electric high-voltage insulating material must be used, the cost is further increased. 2) Ozone generation is inevitable due to air discharge. In recent years, due to environmental problems, the generation of ozone, which is undesirable for the human body, must be avoided as much as possible. 3) Charging tends to be uneven. That is, in order to cause a discharge phenomenon, generally, a wire and a shield case are arranged around the wire, and a high voltage is applied between them. Deposition and unstable discharge. Therefore, the charging of the latent image holding member becomes non-uniform, and unevenness occurs on the image. In particular, at the time of negative corona discharge, this product becomes a stain on the wire and makes the discharge extremely unstable. Therefore, regular wire cleaning becomes indispensable, and maintenance is troublesome. In order to improve the drawbacks of these corona discharge devices, it has been proposed to use a contact charging device to provide a compact charging device that generates less ozone with a low-voltage power supply (see, for example, JP-A-63-149669). ).

As for the latent image holding member which is the core of the electrophotographic technique, inorganic photoconductive substances such as selenium, arsenic-selenium alloy, cadmium sulfide, zinc oxide and amorphous silicon have been used as the photoconductive material. Although they have been used, recently, various organic photoconductive substances which are non-polluting and have advantageous film-forming properties and productivity have been developed. Among the organic latent image holding members, a so-called function-separation type laminated latent image holding member in which a charge generation layer and a charge transport layer are stacked has been widely used in practice because of its high sensitivity and long life.

[0004]

However, when a charging device and method for charging by contacting the latent image holding member are used, (1) the photoconductive layer of the latent image holding member is generally provided on a conductive substrate. However, since the charging member directly contacts the photoconductive layer, if there is a defect in the photoconductive layer, current leakage from the charging member concentrates, the latent image holding member is unevenly charged, and a band-shaped image defect occurs. . At this time, the charging member itself is damaged by the leak current and cannot be used. (2) When defects such as adhesion of foreign matter, dirt, and fine holes are present on the surface of the base, image defects caused by the defects may appear on the copy. (3) In the case of the reversal development method, image defects such as minute black spots and background fog may appear on a copy. In particular, under high humidity environmental conditions, ground fog is remarkable and is not practical.

In the reversal developing method, a dark potential portion becomes a white background and a bright potential portion becomes a black background (image area). However, in this system, if there is a local charging failure due to a defect or the like on the latent image holding member. If there are a large number of black spots on a white background, development such as background fogging will occur, resulting in a remarkable image defect. Even if such a local charging defect does not cause any problem when used in regular development, it is easy to cause an image defect in reversal development, and the conventionally obtained multilayer latent image holding It was found that the members had problems with black spots and fogging to varying degrees.

Although various causes can be considered as the cause of this problem, that is, local charging failure, there is a case where charge is locally injected between the conductive substrate as an electrode and the photoconductive layer and the charging potential does not rise. it is conceivable that. The present inventors have conducted various studies to solve these problems, and as a result, by using a specific latent image holding member in an apparatus and a method for charging the charging member by directly contacting the charging member with the latent image holding member. As a result, the present inventor has learned that a charging device and a method which are less likely to cause image defects can be obtained, and arrived at the present invention.

[0007]

That is, the gist of the present invention is to provide a charging device comprising a latent image holding member and a charging member for charging the latent image holding member by contacting the latent image holding member. A charging device and method comprising a photoconductive layer provided on an aluminum substrate having a surface anodized.

Hereinafter, the present invention will be described in detail. In general, materials used as the base of the holding member for the latent image include aluminum, iron, stainless steel, copper, zinc, nickel, plasticized plastic, glass, and the like. Aluminum, which has good properties and does not impair the electrical characteristics, is widely used.

Usually, when aluminum is used as a drum-shaped substrate, the aluminum buret is processed into an extruded tube by a porthole method, a mandrel method, or the like, and then is drawn to form a drum having a predetermined thickness and outer dimensions. It can be made by performing processing, impact processing, ironing, and the like. However, for example, extrusion processing is usually performed under high temperature and high pressure, so that the surface of the aluminum drum is rough, and the precipitation of dissimilar metals occurs during cooling,
In this state, various defects are formed on the drum surface, and it is difficult to produce a satisfactory product. For this reason, the surface is further cut or, in some cases, another conductive layer is provided on the drum surface and used, but it still has a uniform enough surface for practical use. It can not be said.

The aluminum substrate used in the present invention can be obtained in a desired shape by a process such as drawing, impact, or ironing as described above. Further, mirror finishing by cutting is performed as necessary. The aluminum substrate is preferably subjected to a degreasing treatment by various degreasing methods such as an acid, an alkali, an organic solvent, a surfactant, an emulsion, and electrolysis before the anodizing treatment is performed.

The anodizing treatment is usually carried out, for example, with chromic acid,
It is carried out in an acidic bath such as sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the best results. In the case of anodic oxidation in sulfuric acid,
Sulfuric acid concentration is 50-400g / l, dissolved aluminum concentration is 2-
20 g / l, liquid temperature 10 to 40 ° C., electrolysis voltage 5 to 30
V and the current density are preferably set in the range of 0.5 to ² A / dm ² .

The average thickness of the anodic oxide coating is 0.1 to
Preferably, it is formed to have a thickness of 20 μm. More preferably, it is 1 to 10 μm. In order to enhance the stability of the anodic oxide film formed in this way, for example, a low-temperature sealing treatment in which it is immersed in an aqueous solution containing nickel fluoride as a main component, or, for example, contains nickel acetate as a main component It is preferable to perform high-temperature sealing treatment immersed in an aqueous solution and other sealing treatments such as steam sealing and boiling water sealing.

The concentration of the aqueous nickel fluoride solution used in the case of the low-temperature sealing treatment can be appropriately selected, but is most effective when used in the range of 2 to 10 g / l. In order to smoothly proceed with the sealing process, the processing temperature is set to 15
-40 ° C, preferably 25-35 ° C, and the pH of the aqueous nickel fluoride solution is 4.5-6.5, preferably 5.5-5.5.
It is better to process within the range of 6.0. In this case, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia or the like can be used as the pH adjuster. The processing time is preferably within a range of 1 to 3 minutes per 1 μm of the film thickness. In order to further improve the film properties, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant and the like may be added to the nickel fluoride aqueous solution. Next, it is washed with water and dried to complete the low-temperature sealing treatment.

As the sealing agent in the case of the high-temperature sealing treatment, an aqueous solution of a metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel-cobalt acetate, barium nitrate and the like can be used. In particular, nickel acetate is used. Is preferred. The concentration when using an aqueous nickel acetate solution is 3 to 20.
It is preferably used within the range of g / l. Processing temperature is 6
The treatment is preferably performed at 5 to 100 ° C., preferably 80 to 98 ° C., and the pH of the aqueous nickel acetate solution is in the range of 5.0 to 6.5. Here, ammonia water, sodium acetate, or the like can be used as the pH adjuster.

The processing time is 10 minutes or more, preferably 20 minutes or more. Also in this case, sodium acetate, an organic carboxylate and an anionic or nonionic surfactant may be added to the nickel acetate aqueous solution in order to improve the physical properties of the film. Then, after washing with water and drying, the high-temperature sealing treatment is completed. The photoconductive layer is provided on the anodic oxide film formed as described above, but a known undercoat may be provided between the anodic oxide film and the photoconductive layer. Examples of the undercoat material include polyvinyl alcohol, casein, casein sodium, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, and phenol resin. The thickness of the undercoat layer is preferably 5 μm or less, particularly preferably 2 μm or less.

As the photoconductive layer provided on the substrate formed as described above, various inorganic or organic photoconductive layers can be used, and a laminated photoconductive layer comprising a charge generation layer and a charge transfer layer is used. The use of layers is very useful. As the photoconductor used for the charge generation layer, selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide and other inorganic photoconductors, phthalocyanine, azo, quinacridone, polycyclic quinone, perylene, indigo, benzimidazole and the like Various organic pigments can be used. Among them, azo pigments such as monoazo, bisazo, trisazo, and borazos; metal-free phthalocyanines; coordination of metals such as copper, indium chloride, gallium chloride, tin, oxytitanium, zinc, and vanadium, or oxides and chlorides thereof. Phthalocyanines are preferred.

The charge generation layer is formed as a uniform layer of these substances or in a state where fine particles are dispersed in a binder. Examples of the binder resin used here include polyvinyl butyral, phenoxy resin, epoxy resin, polyester resin, acrylic resin, methacrylic resin, polyvinyl acetate, polyvinyl chloride, methyl cellulose, and polycarbonate resin. Binder resin 100
It is preferable that the photoconductor is contained in an amount of 20 to 300 parts by weight, more preferably 30 to 150 parts by weight. The thickness of such a charge generation layer is usually 5 μm or less, preferably 0.01 to 1 μm, more preferably 0.15 to
0.6 μm is appropriate.

As the charge transfer material used in the charge transfer layer, various materials can be used. For example, hydrazone derivatives,
Examples include pyrazoline derivatives, heterocyclic derivatives such as carbazole, indole, and oxadiazole, derivatives of arylamines such as triphenylamine, stilbene derivatives, and high molecular compounds having the above compound in the side chain or main chain. Among them, hydrazone derivatives, arylamines and stilbene derivatives are more preferred charge transfer materials. A binder resin is blended with these charge transfer materials as needed.

Preferred binder resins include vinyl polymers such as polymethyl methacrylate, polystyrene and polyvinyl chloride and copolymers thereof, polyarylate resins, urethane, urea, melamine polycarbonate, polyester, polysulfone, phenoxy resins, epoxy resins, and the like. Examples thereof include silicone resins, and partially crosslinked and cured products thereof. The charge transfer material is preferably contained in an amount of 30 to 200 parts by weight, particularly 50 to 150 parts by weight, per 100 parts by weight of the binder resin.

The charge transfer layer may contain various additives such as an antioxidant and a sensitizer, if necessary. The thickness of the charge transfer layer is usually 10 to 40 μm, preferably 10 to 40 μm.
Used with a thickness of ２５25 μm. As another example of the photoconductive layer, there is a dispersion-type conductive layer in which the above-described photoconductor particles are dispersed in a binder made of a binder resin and the above-described charge transfer material. In this case, the total content of the photoconductor and the charge transfer material is preferably 20 to 200 parts by weight, and particularly preferably 40 to 200 parts by weight based on 100 parts by weight of the binder resin.
150 parts by weight are preferred.

The shape of the charging member for charging the latent image holding member is not limited as long as it comes into contact with the latent image holding member, such as a brush, a blade, or a roller. preferable. When the charging device is in the form of a roller, it usually comprises a core material and a charging member that covers the core material. As the charging member, a conductive or semiconductive elastic body having relatively low hardness is preferable because it needs to be brought into close contact with the latent image holding member. For example, conductive particles such as carbon or other semiconductive particles in a rubber material are preferable. And a conductive rubber containing the same.

Further, the charging member is divided into a supporting member and a surface member, and the supporting member has an appropriate hardness to maintain an appropriate electric resistance by the surface member while maintaining the adhesion to the latent image holding member. A function-separated charging member can also be used. Hereinafter, a roller-shaped charging member will be described with reference to FIG. 1 showing an example of the charging device of the present invention.

In FIG. 1, reference numeral 1 denotes a latent image holding member of the present invention. It is an inorganic and organic latent image holding member, and any shape such as a drum shape or a sheet shape can be used according to the purpose. In the figure, reference numeral 2 denotes a core material supporting the charging member. Both ends of the core material are held by bearings supported by a suitable pressure applying device, for example, a metal spring or the like, for bringing the charging member into contact with the latent image holding member. A bias potential is then applied using the core bearing or other electrical contact means. Any material may be used as the material of the core as long as it has conductivity, and usually, metal is often used. Examples of metals include iron, copper, brass,
Stainless steel, aluminum, etc. are available. In addition, a resin molded product in which a conductive organic material such as carbon is kneaded can be used.

In the drawing, reference numeral 3 denotes a roller-shaped support member, which comes into close contact with the latent image holding member and rotates. The driving force for rotation may be applied from the outside, or may be freely rotated by contact friction with the latent image holding member. Any material may be used as the material of the support member as long as it has conductivity or semi-conductivity. Usually, a rubber material that is an elastic body having a relatively low surface hardness because it is necessary to bring the latent image holding member into close contact with the rubber member, for example,
NBR, EPDM, silicon, neoprene, or natural rubber materials, and conductive rubber obtained by kneading conductive particles such as carbon or semiconductive particles into these rubbers are used. Of course, a material other than an elastic material such as rubber may be used as long as it has a surface that is precisely processed so as to maintain good adhesion. However, when such a contact charging device is used, uniformity of charging becomes a problem, and if the electrical conductivity of the charging member is too large, uneven charging of the latent image holding member occurs. At the time of non-uniformity and reversal development, an image defect becomes fog of a white portion. Conversely, if the electric conductivity is too small, poor charging occurs, and the image carrier is not sufficiently charged.
Therefore, the resistivity of the support member is 10 ² -10 ¹⁵ Ω.
cm, particularly preferably 10 ⁴ -10 ¹² Ωcm.

Reference numeral 4 in the figure is provided when a function-separating type charging member is used as the surface member. As a material, a polyamide resin, a fluorine resin, a vinyl chloride resin, an acrylic resin, other various polyester resins, and the like are used as main components. The resistivity of the surface member is 10 ³ -10 ¹⁴ Ωcm
, And particularly preferably 10 ⁵ -10 ¹² Ωcm. The thickness of the surface member is preferably thicker in consideration of the durability due to wear as a charging member. However, if the thickness is too large, the charging ability of the latent image holding member deteriorates.
00μ, preferably 0.1μ-500μ. As a method of manufacturing the surface member, the surface member is formed on the support member by a dipping method, a spray method, a vacuum deposition method, a plasma coating method, etc. In these methods, the dip method is advantageous in terms of a manufacturing process. .

In order to charge the latent image holding member, only a DC voltage may be applied to the charging member, that is, the core material, or AC may be superimposed on DC. Any alternating voltage may be used as long as it varies periodically. The range of the voltage is positive or negative 100 to 4000 V, preferably 300 to 3000 V in the case of a DC voltage. As the superimposed AC voltage, the peak-to-peak voltage is 100 to 4000 V, preferably 30 to 40 V.
0-3000V.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples without departing from the scope of the invention.

Embodiment 1 FIG. An aluminum cylinder having a wall thickness of 0.75 mm, an outer diameter of 30 mm, and a length of 246 mm was produced by ironing the aluminum extrusion tube. The maximum surface roughness of this aluminum cylinder was measured.
It was 5 μm. This aluminum cylinder was degreased and washed in a 30 g / l aqueous solution of a degreasing agent NG- # 30 (manufactured by Kizai Co., Ltd.) at 60 ° C. for 5 minutes. Subsequently, after washing with water, it was immersed in 7% nitric acid at 25 ° C. for 1 minute. After further washing with water, anodic oxidation was carried out in a 180 g / l sulfuric acid electrolytic solution (dissolved aluminum concentration: 7 g / l) at a current density of 1.0 A / dm ² to form an anodic oxide film having an average film thickness of 6 μm. Then, after washing with water, a high-temperature sealing agent top seal DX-500 containing nickel acetate as a main component (Okuno Pharmaceutical Co., Ltd.)
Was immersed in a 10 g / l aqueous solution at 90 ° C. for 20 minutes for sealing. Subsequently, after washing with water, it was immersed in a hot water bath of 95 ° C. for 10 minutes, taken out and dried.

On the other hand, oxytitanium phthalocyanine 1
0 parts by weight, polyvinyl butyral (Sekisui Chemical Co., Ltd.
To 5 parts by weight of Esrec BH-3) was added 500 parts by weight of 1,2-dimethoxyethane, and the mixture was pulverized and dispersed by a sand grind mill. An aluminum cylinder provided with the previously formed anodic oxide film was dip-coated on this dispersion, and a charge generation layer was provided so that the film thickness after drying was 0.4 μm.

Next, this aluminum cylinder was mixed with 56 parts by weight of a hydrazone compound shown below.

[0031]

Embedded image

14 parts by weight of the following hydrazone compound

[0033]

Embedded image

1.5 parts by weight of the following cyano compound

[0035]

Embedded image

Para-3,5-di (tert-butyl)
8 parts by weight of hydroxytoluene and polycarbonate resin (NOPAREX (registered trademark) 702, manufactured by Mitsubishi Chemical Corporation)
5A) Dip-coating in a solution in which 100 parts by weight of 1,4-dioxane was dissolved in 1000 parts by weight, and the film thickness after drying was 17
The charge transfer layer was provided to have a thickness of μm.

The latent image holding member 1 was manufactured as described above. Next, a stainless steel rod having a diameter of 6 mm is used as the core material 2, and a conductive EPD having a resistance of 10 ⁸ Ωcm is used as the support member 3.
A charging member using a 12 mm diameter roller using M rubber was produced. Then, instead of the latent image holding member and the corona charger of a commercially available printer (PR406LM manufactured by NEC Corporation), the latent image holding member and the charging member prepared above are used, and the charging member is brought into contact with the latent image holding member. As a result, the image was evaluated by applying DC-1200 V to the core material as a power source bias. As a result, good images were obtained for white background, black background, and halftone images.

Further, no black band-like image defect, which is generated when electric charge is leaked, occurs even for a defect such as a local concave portion of the photoconductive layer.

Embodiment 2 FIG. The images were evaluated in the same manner as in Example 1 except that the supporting member was made of a conductive EPDM rubber having a resistance of 10 ⁴ Ωcm. As a result, good images were obtained for white, black, and halftone images. In addition, black band-like image defects generated when electric charge leaked did not occur even for defects such as local concave portions of the photoconductive layer.

Embodiment 3 FIG. Power supply bias DC-700V
The image was evaluated in the same manner as in Example 1 except that an alternating current having a peak-to-peak voltage of 1400 V was superimposed on the image.
Good images were obtained for both halftone images. In addition, black band-like image defects generated when electric charge leaked did not occur even for defects such as local concave portions of the photoconductive layer.

Embodiment 4 FIG. The resistance of the supporting member is 10 ⁴ Ωcm
As a result of evaluating the image in the same manner as in Example 3 except that the image quality was changed to, good images were obtained for white, black, and halftone images. In addition, black band-like image defects generated when electric charge leaked did not occur even for defects such as local concave portions of the photoconductive layer.

Embodiments 5 to 8 The surface is cut and mirror finished to a thickness of 1.0 mm, an outer diameter of 30 mm, and a length of 24
The images were evaluated in the same manner as in Examples 1 to 4, except that a 6 mm aluminum cylinder was used. As a result, good images were obtained for all of the white, black, and halftone images. In addition, no black band-like image defects generated when electric charge leaked were generated for defects such as local concave portions of the photoconductive layer.

Embodiment 9 FIG. As a support member, resistivity 10 ⁸
Ωcm conductive EPDM rubber and resistivity 10
Surface member made of polyamide resin of ¹⁰ Ωcm (film pressure 1
The image was evaluated in the same manner as in Example 1 except that a charging member using a roller having a diameter of 12 mm provided with a .mu.m) was used. As a result, good images were obtained for white, black, and halftone images. In addition, black band-like image defects generated when electric charge leaked did not occur even for defects such as local concave portions of the photoconductive layer.

Embodiment 10 FIG. As a supporting member, a resistivity of 10
^Using a conductive EPDM rubber of ⁸ Ωcm and a resistivity of 1
An image was evaluated in the same manner as in Example 5 except that a charging member using a roller having a diameter of 12 mm provided with a surface member (thickness: 1 μm) made of a polyamide resin of 0 ¹⁰ Ωcm was evaluated. Good images were obtained for both halftone images. In addition, black band-like image defects generated when electric charge leaked did not occur even for defects such as local concave portions of the photoconductive layer.

Comparative Example 1 An aluminum cylinder was produced in the same manner as in Example 1, and instead of not providing an anodic oxide film, degreasing and washing were performed with trichlorene. As in Example 1, a charge generation layer and a charge transfer layer were sequentially formed. Next, the same charging member as in Example 1 was produced. As in Example 1, as a result of evaluating the image, many image defects were observed especially in the halftone image, and the fog was large.

Comparative Example 2 The image was evaluated in the same manner as in Comparative Example 1 except that the supporting member was made of a conductive EPDM rubber having a resistance of 10 ⁴ Ωcm. As a result, many image defects were observed particularly in a halftone image, and fog was large. In addition, black band-like image defects generated when electric charge leaked also occurred for defects such as local concave portions of the photoconductive layer.

Comparative Example 3 Power supply bias DC-700V
The image was evaluated in the same manner as in Comparative Example 1 except that an alternating current having a peak-to-peak voltage of 1400 V was superimposed.

Comparative Example 4 The resistance of the supporting member is 10 ⁴ Ωcm
As a result of evaluating the image in the same manner as in Comparative Example 3 except that the image quality was changed, many image defects were observed especially in the halftone image, and the fog was large. In addition, black band-like image defects generated when electric charge leaked also occurred for defects such as local concave portions of the photoconductive layer.

Comparative Example 5 The surface is cut to a mirror finish with a thickness of 1.0 mm, an outer diameter of 30 mm, and a length of 246 m.
The image was evaluated in the same manner as in Comparative Example 1 except that an aluminum cylinder having a m of m was used. As a result, many image defects were observed especially in the halftone image, and the fog was large.

Comparative Example 6 The resistance of the supporting member is 10 ⁴ Ωcm
As a result of evaluating the image in the same manner as in Comparative Example 5 except that the image quality was changed, many image defects were observed particularly in the halftone image.
There were many fog. In addition, black band-like image defects generated when electric charge leaked also occurred for defects such as local concave portions of the photoconductive layer.

Comparative Example 7 Power supply bias DC-700V
The image was evaluated in the same manner as in Comparative Example 5 except that an alternating current having a peak-to-peak voltage of 1400 V was superimposed. As a result, many image defects were observed particularly in the halftone image, and the fog was large.

Comparative Example 8 The resistance of the supporting member is 10 ⁴ Ωcm
As a result of evaluating the image in the same manner as in Comparative Example 7 except that the image quality was changed, many image defects were observed particularly in the halftone image.
There were many fog. In addition, black band-like image defects generated when electric charge leaked also occurred for defects such as local concave portions of the photoconductive layer.

[0053]

According to the charging device and method obtained by the present invention, an aluminum substrate which cannot be used as a latent image holding member, which has many dirt, projections, scratches, dents and the like on its surface as it is, can be anodized. By performing the treatment, those defects can be removed. As a result, it is possible to provide a good charging device and method which are less susceptible to image defects caused by image defects and defects such as local dents in the photoconductive layer, which occur when the contact charging device and method are used.

Further, even if the charging device and method obtained by the present invention are used in a commercially available copying machine or in an electrophotographic system including a reversal developing system process in which a defect of a substrate is more severe and an image is more likely to appear, Under a wide range of environmental conditions including wet conditions, a good image with very little fog and other image defects can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of an example of a charging device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Latent image holding member 2 Core material 3 Support member 4 Surface member

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-242264 (JP, A) JP-A-63-298250 (JP, A) JP-A-63-267952 (JP, A) JP-A 64-64 44964 (JP, A)

Claims (2)

(57) [Claims] 1. A charging device comprising: a latent image holding member; and a charging member that contacts and charges the latent image holding member.
A charging device, wherein the latent image holding member has a photoconductive layer provided on an aluminum substrate whose surface is anodized. 2. A charging method for charging a charging member by bringing the charging member into contact with a latent image holding member, wherein the latent image holding member is provided with a photoconductive layer on an aluminum substrate whose surface is anodized. A charging method comprising: