JPH0480781A - Image forming device - Google Patents

Abstract

PURPOSE:To always maintain high image quality even in the case of repeatedly using over a long period by making a conductivity member always, or whenever necessary come into contact with the surface of a photosensitive body and also impressing a positive or negative voltage, or both of the positive and negative voltages on the member. CONSTITUTION:A conductive felt-like structural body 11 and a brush-like structural body 12 are brought into contact with all over the surface of the photosensitive body 1 by making them always come into contact with the surface of the photosensitive body 1, or making them intermittently come into contact with the surface of the photosensitive body 1 at a prescribed time interval whenever necessary and so forth. And the positive voltage is impressed on the conductive felt-like structural body 11 and the negative voltage is impressed on the conductive brush-like structural body 12, or the positive voltage and the negative voltage are impressed on either of the structural bodies 11 and 12. Either of a DC field and an AC field which is biased to positive or negative is good for the positive and negative voltage. By impressing the positive and negative electric fields, an ionic material provided with hydrophilic property adhering on the surface of the photosensitive body can be removed. Thus, the stable image of good quality can be obtained over a long time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrophotographic image forming apparatus, and in particular, to removing hydrophilic substances adhering to the surface of a photoreceptor to form a stable image. It depends.

(Prior Art) FIG. 6 shows a schematic configuration diagram of an electrophotographic image forming apparatus. To explain the outline of the operation of this apparatus, the drum-shaped photoreceptor l rotates in the direction of the arrow, and at this time, the charging charger 2, the surface of the photoreceptor is uniformly charged. Then, the light modulated by the image signal is subjected to imagewise exposure in the exposure section 3 to form an electrostatic latent image on the surface of the photoreceptor, and then a toner image is formed in the developing device 4.

After this toner image is transferred onto a copy paper 9 by a transfer charger 5, the copy paper is separated from the photoreceptor 1 by a separation charger 6 and fixed by a fixing device 10 to become a hard copy. On the other hand, the toner image on the photoreceptor 1 after the transfer is cleaned by a cleaning device 7, and the photoreceptor 1 is subjected to a charge removing action by a charge removal lamp 8, thereby completing a series of copying steps.

The photoreceptor 1 has Se or S on a conductive support.
e alloy (Se-As, 5e-Te, 5e-As -
Those with a photoconductive layer mainly composed of Te, etc.), those with an inorganic photoelectric material such as zinc oxide or cadmium sulfate dispersed in a binder, and those with a photoconductive layer mainly composed of poly-N-vinylcarbazole and trinitrofluorenone or azo pigments. Those using organic photoconductive materials (OPC・-Orgnjc Pho
to -Conductor) and those using amorphous silicon-based materials are generally used.

The basic characteristics required of the photoreceptor 1 are as follows: (A) Capable of being charged to an appropriate potential in the dark.

(B) Less charge dissipation in the dark.

(C) Charge can be quickly dissipated by light irradiation.

Examples include.

Furthermore, the characteristics required in use are (D) resistance to mechanical and chemical loads received in electrophotographic processes.

(Problems to be Solved by the Invention) From the viewpoint of the above-mentioned characteristics (A) to (D) imposed on the photoreceptor, for example, when looking at the amorphous silicon photoreceptor, it has high surface hardness and mechanical resistance. It has excellent durability against physical loads (contact parts of developing, transfer, and cleaning devices) and relatively high photosensitivity. However, the charging ability is relatively low,
The manufacturing cost is high, it is vulnerable to chemical loads (exposure to 05 and NOx generated by corona discharge during charging, or composite products of these and atmospheric components), and the surface resistance of the photoreceptor depends on humidity. and become smaller, resulting in so-called "image flow".
The drawback is that it may generate abnormal images.

Furthermore, the Se-based photoreceptor has excellent photosensitivity and charging ability, and has been commonly used for the longest time.

However, there are drawbacks in that scratches are likely to occur on the surface of the photoreceptor due to the mechanical load, and abnormal images such as white stripes or black stripes are likely to occur in terms of image quality.

Incidentally, in recent years, organic photoconductors (OPCs) have come into widespread use due to their low manufacturing cost, low environmental pollution, and relatively flexible photoconductor design. However, because it is an organic material, its surface hardness is low, and the photoreceptor surface is prone to wear and scratches due to the mechanical load in the electrophotographic process, resulting in a decrease in charging potential due to wear, and local streak-like abnormal images. This causes the occurrence of

In order to eliminate the above-mentioned drawbacks regarding the mechanical durability of the Se-based and OPC-based systems, a protective layer is provided on the surface of the photosensitive layer of the photoreceptor to improve the durability against mechanical loads received inside and outside the copying machine. Proposed. However, it has been found that when the photoreceptor is used for a long period of time, the same problem as with the amorphous silicon type photoreceptor described above occurs, such as blurring of images due to high humidity.

The causes of image deletion can be broadly divided into (a) repeated exposure to corona discharge in the charging charger 2 used for charging purposes, and the surface of the photoreceptor l is chemically damaged by ozone generated by the corona discharge; deteriorated to
For example, it becomes oxidized and becomes hydrophilic.

(b) Ozone caused by corona discharge and positive or negative ions react with moisture in the air, impurities such as carbon dioxide gas, and hydrophilic compounds containing, for example, nitrogen compounds, carboxyl groups, aldehydes, etc., are formed, and these Adheres to the photoreceptor surface,
As it accumulates, it becomes hydrophilic.

There are two possible causes (a) and (b) above, and in either case, water is adsorbed to the surface of the photoreceptor, which has become hydrophilic, and the resistance in the two-dimensional direction of the surface decreases, resulting in abnormal images. Occur.

Specifically, in the case of the amorphous silicon-based photoreceptor, the above cause (A) is considered to be dominant, and if a protective layer is formed on the surface of the photoreceptor, cause (A) or cause (B) is considered to be the dominant cause. In any case, the reliability of the photoreceptor is an important issue.

The present invention provides an electrophotographic image forming apparatus that solves the problem of image smearing in the various photoreceptors described above under high temperature and high humidity conditions, and that can always maintain high image quality even after repeated use over a long period of time. The purpose is to provide.

(Means for Solving the Problems) In order to solve the above-mentioned problems and achieve the objects, the present invention provides an electrophotographic image forming apparatus in which a pair of conductive members are brought into contact with the surface of a photoreceptor, and the conductive The hydrophilic substance adhering to the surface of the photoreceptor is removed by applying a positive voltage or a negative voltage to each of the pair of members, or applying a positive or negative voltage to only one of the pair. .

Further, the conductive member that contacts the surface of the photoreceptor is composed of a felt-like or brush-like structure, a magnetic brush, an elastic blade, an elastic roller, or the like.

(Function) The present invention enables a substantially conductive member to be brought into constant or occasional contact with the surface of a photoreceptor, and by applying a positive voltage, a negative voltage, or both positive and negative voltages. A hydrophilic substance adhering to the surface of a photoreceptor that effectively removes the ions that make up the majority of the ions, making it possible to obtain stable, high-quality images over a long period of time.

(Embodiment) FIG. 1 shows a first embodiment of the present invention, and the figure shows an example in which both positive and negative DC voltages are applied to a conductive felt-like structure 11 and a brush-like structure 12. , the same applies to alternating voltage. In the figure, numerals 1 to 10 indicate the same components as those shown in FIG. 6, except that the conveying direction from the copy paper 9 to the fixing device 10 is different.

The conductive felt-like structure 11 and the brush-like structure 1
2, conductive fibers are used. The second type of conductive fibers include those processed from metal itself into fibers, those whose surfaces are coated with metal by methods such as plating, vacuum evaporation, and sputtering, and those whose surfaces are covered with conductive particles (carbon, etc.). These include those formed with an organic layer in which metal powder, etc.) are dispersed, and those formed by blending or multicore composite spinning of conductive fine particle dispersed polymers, etc., and the volume resistivity is preferably 100 Ωcm or less.

In addition, the fiber thickness is generally 5 to 15 (denier/filament), the brush density is 10,000 to 100,000 (strands/inch'), and the brush length is 1 ~]0wl1 is optimal.

The conductive felt-like structure 11 is formed in the form of a sheet or block composed of the conductive fibers entangled with each other, and a method that utilizes the fullness effect like that of wool fibers;
It is created by a method of inserting other fibers into a woven fabric from the outside with a needle or the like, or by a method of creating a non-woven fabric.

In addition, the conductive brush-like structure 12 can be produced by directly fixing the fibers forming the brush on a support, or by woven brush fibers (
It is created by a method such as fixing a pile (pile) on a support using a method such as gluing. In this case, the bristles of the brush may have either cut or looped brush fibers.

If fibers with catalytic activity (adsorption ability, etc.) are used as the conductive fibers constituting the conductive felt-like structure or brush-like structure, or as constituent elements other than the conductive fibers, the interaction with voltage application may occur. This makes it possible to more efficiently remove hydrophilic substances such as ionic substances adhering to the surface of the photoreceptor. The fibers having catalytic activity may be those having catalytic activity themselves, or those having a material having catalytic activity retained on the surface of the fibers by a method such as coating. For example, metals with catalytic activity (
Ni, PL, Pd, Ag, Au, Ti, V.

Cr, Mn, Fe, Co, Sn, W, etc.) are processed into fibers, and these metal fibers are coated on the fiber surface by methods such as plating, vacuum deposition, and sputtering.

Conductive felt-like structure 11 constructed by the method described above
A positive voltage is applied to the conductive brush-like structure 12, and a negative voltage is applied to the conductive brush-like structure 12, or a positive voltage and a negative voltage are applied to only one of the structures 11 and 12. These positive and negative voltages may be either a direct current electric field or an alternating electric field biased positively or negatively, but the appropriate voltage range is about 1 to +00V, and this positive and negative electric field is applied. As a result, the ionic hydrophilic substance adhering to the surface of the photoreceptor is removed.

The conductive felt-like structure 11 and the brush-like structure 1
2 is in constant contact with the surface of the photoconductor 1 (over the entire length in the longitudinal direction), intermittently at predetermined time intervals, or in half without contacting the entire length in the longitudinal direction of the photoconductor surface. The entire surface of the photoreceptor is brought into contact with the photoreceptor by sequentially contacting the entire length in equal parts of ]/N.

Further, the positive and negative voltages applied to the conductive felt-like structure 11 and the brush-like structure 2 are applied either constantly or at predetermined time intervals when these structures are in contact with the photoreceptor. You can also do this.

Next, conductive felt-like structure 11 and brush-like structure 1
Specific examples of 2 are shown in FIGS. 2(a) and 2(b), and the experimental results will be described.

[Specific example of conductive felt-like structure 11... Fig. 2 (a
)] (a) A felt sheet (width 30 mm, thickness 6 mm) made using conductive synthetic fiber (manufactured by Toshi Co., Ltd.: 5A-7) is spirally attached to a stainless steel core (10 mm, jφ). A conductive felt roller was formed by attaching and fixing the felt roller.

(b) Concrete (a) on the same core bar as in the above concrete example (a)
It was created by blending conductive synthetic fiber equivalent to 2:1 with acrylic fiber (thickness 6 denier/filament) whose fiber surface was coated with Nj, P5 Pd, Ag, and Au respectively by sputtering method. Felt sheet (width 30mm,
A conductive felt roller was formed by spirally winding and fixing a conductive felt roller having a thickness of 61T1 m.

(Experimental results of conductive felt-like structure 11) Continuous image collection and image quality evaluation were performed using a plain paper copying machine equipped with conductive felt rollers shown in each of the above specific examples (a) and (b). The results are shown in Table (1) below.

For the evaluation of the image, the characteristic value was whether it was well resolved on the resolution chart of 5 lines/anus or on the copy paper 9.

The photoreceptor 1 used in this experiment was As-3e based (A
A protective layer of polyurethane resin containing SnO dispersed therein as a resistance control agent is formed on the photosensitive layer (containing s = 35.5 iut%).

The applied voltage was a direct current voltage or an alternating voltage in each electric field, and in the case of a direct current electric field, 20 V was applied to both the positive and negative surfaces of the photoreceptor. In the case of an alternating electric field, the frequency was 1 kHz, Vp-p was 20 V, and 20 V was applied to both positive and negative DC components.

Further, as for the field strength, a positive field was applied to the felt-like structure 11 and a negative field was applied to the push-like structure 12.

Furthermore, as a comparative example, evaluation was also conducted in the case where the felt-like structure 11 was not provided. In addition, during this experiment (a
) and (b) are rotated in the reverse direction with respect to the photoconductor to increase the contact efficiency.Table 1) ◎Very good resolution ○Good resolution △Slight resolution As is clear from Table (1) above, in the case of the comparative example, image blurring occurred in a hot and humid environment after 10,000 cycles of copying, but due to the conductive felt-like structure, In the specific examples (a) and (b) in which a positive or negative electric field was applied, no image blurring was observed even after 50,000 cycles of copying, regardless of whether the electric field was DC or alternating, and stable images (two ) was obtained.

(Conductive brush-like structure) Specific example of 2...Figure 2 (b
)) (c) Using conductive synthetic fiber (manufactured by Toshi Co., Ltd.: 5A-7) on a stainless steel core (10 mmφ), fiber (thickness 6 denier/filament), density (5 pieces/inch') A conductive brush roller with a length of 9 bristles (6M) and a loop-shaped bristles was formed.

(d) Specific example (c) on the same core metal as the above specific example (c)
Created by blending conductive synthetic fiber equivalent to 2:1 with acrylic fiber (thickness 6 denier/filament) whose fiber surface is coated with Ni, Pt, Pd, Ag, and Au by sputtering at a ratio of 2:1. The resulting pile was fixed to create a conductive brush roller having the same density, bristles length, and bristle tip shape as in Example (c).

(Experimental results of the conductive brush-like structure 12) The photoreceptor, applied voltage, and evaluation criteria used in the experiment were as described in the specific example (a).
Same as b). This experimental example is based on each of the above specific examples (c) and (
Using a plain paper copying machine equipped with a conductive brush roller shown in d), continuous image acquisition and image quality evaluation were performed, and the results were the same as those shown in the table (]) above. As a comparative example in this case, evaluation was also conducted in the case where the conductive brush-like structure 12 was not provided.

Next, various examples of removing the hydrophilic substance adhering to the surface of the photoreceptor described above will be described with reference to FIGS. 3 to 5.

FIG. 3 shows a second embodiment of magnetic brushes 13, 14 to which a negative voltage (direct current or alternating current) is applied.

As the magnetic particles for forming the magnetic brushes 13 and 14, any commonly used magnetic particles such as N1 powder, Fe powder, ferrite powder, magnetite powder, etc. can be used. Further, a structure in which the above-mentioned magnetic particles, conductive filler, etc. are dispersed in a resin can be used.

Furthermore, when the above-mentioned N powder is used as the magnetic particles for forming the magnetic brushes 13 and 14, for example, the Ni particles not only have magnetism by themselves, but also have catalytic activity (adsorption ability, etc.). Therefore, hydrophilic substances such as ionic substances attached to the surface of the photoreceptor due to interaction with voltage application can be removed more efficiently.

Furthermore, even metals that do not have magnetism and cannot form a magnetic brush by themselves, but have high catalytic activity, can be used by coating at least a portion of the surface of the magnetic particles as described above. Similar to powder, it has a high hydrophilic substance removal effect. In addition to N1, metals having such catalytic activity include Pt, Pd, Ag, Au, and the like.

In addition, methods for coating at least a part of the surface of the magnetic particles with metals such as N include plating, vacuum evaporation,
Coating may be performed using a method such as sputtering. In addition, the size of magnetic particles is 50 to 300 μm.
m is optimal.

The method of applying voltage to the magnetic brushes 13 and 14 and the method of bringing the magnetic brushes into contact with the photoreceptor are the same as in the specific example of the first embodiment shown in FIG. 2, so their explanation will be omitted.

(Specific example of magnetic brush 13.14) (e) Ferrite powder or N1 with an average particle size of 100 μm
Magnetic brush unit 13A with 500 g of powder each.

14A and magnetic brushes 13 and 14 were configured to be stirred by sleeve rollers 13R and 14R.

(f) Approximately 2 times each of Nj, Pt, Pd, Ag, and Au are applied to the surface of ferrite powder with an average particle size of 100 μm by sputtering.
000 g each of the coated material was put into the magnetic brush units 13A and 14A, and the sleeve roller 1
A magnetic brush for stirring was constructed with 3R and 14R.

(Experimental results for magnetic brushes 13 and 14) The photoreceptor, applied voltage, and evaluation criteria used in the experiment were the same as those in the specific examples (a) and (b). In this experimental example, continuous image acquisition and image quality evaluation were performed using a plain paper copying machine equipped with the magnetic brush shown in each of the specific examples (e) and (f) above.The results were the same as those in Table (1) above. was gotten. Note that, as a comparative example, evaluation was also conducted in the case where the magnetic brushes 13 and 14 were not arranged.

FIG. 4 shows a third embodiment of a conductive elastic blade 15, 16 to which positive and negative voltages (direct or alternating) are applied.

The constituent materials of this conductive elastic blade include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-vinyl acetate polymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and Ebiglol. Conductive materials such as hydrin rubber, nitrile rubber, nitrile/isoprene rubber, acrylic rubber, urethane rubber, polysulfide rubber, silicone rubber, fluororubber, foams thereof, and various metal powders, metal oxide powders, carbon powders, etc. A conductive elastic material containing a dispersed filler is used.

In addition, if particles with catalytic activity (adsorption ability, etc.) are used as a conductive filler added to the elastic blade or as an additive other than the conductive filler, particles that have catalytic activity (adsorption ability, etc.) may adhere to the surface of the photoreceptor due to interaction with the applied electric field. Hydrophilic substances such as ionic substances can be removed more efficiently.

The material with high catalytic activity is preferably activated carbon, which is a porous carbonaceous material with a large specific surface area and adsorption capacity. i.e. wood, saw shavings, coconut shells, lignite,
It is obtained by carbonizing a raw material such as lignite, peat, coal, etc., and then performing an activation process using a chemical such as zinc chloride or magnesium chloride, or an activation method using a gas such as steam or carbon dioxide scum.

Typical physical properties of activated carbon include a specific surface area of 800~
1200n (7g, pore volume 0.2-2 cnJ/g
, pore diameter of 1 to 4M, etc. Furthermore, the chemical composition of activated carbon is mainly composed of carbon, and also contains trace amounts of impurities such as hydrogen, oxygen, nitrogen, sulfur, and inorganic components (silicon, aluminum, iron, etc.).

Activated carbon can be uniformly dispersed in conductive elastic blades or
If necessary, the concentration distribution may be such that a large amount is contained near the surface of the elastic blade (the surface in contact with the photoreceptor).

and a method of applying voltage to the elastic blade 15.16;
The method of bringing the elastic blade into contact with the photoreceptor is the same as the specific example of the first embodiment shown in FIG. 2, so the explanation will be omitted.

(Specific example of conductive elastic blade) (g) A mixture consisting of the following forming components of the conductive elastic blade was kneaded in two rolls in a 30 x 3] 8 x 3 (mm) sheet mold, and then 100 parts by weight of the mixture was mixed. On the other hand,
Crosslinking agent (2,4-dimethyl-2,4-di-tertiary)
Butyl peroxyhexane: RC- manufactured by Toray Silicon Co., Ltd.
4) was added in an amount of 1.5 parts by weight, and primary vulcanization was performed at 170°C and 710°C
minute (120kg/cil), secondary vulcanization at 200
The holding member 15 is press-molded under the conditions of 0C and 74 hours.
A, conductive elastic blade held fixed at 16A 15.1
6 was formed.

Methylvinylpolysiloxane 100 parts by weight Carbon (Ketchen Black EC) 8 1/Activated carbon powder IQ //Pry silica (
Aerosilicity: R972) 15 II Quartz
20〃(h) In a sheet mold similar to the above (g), a mixture consisting of the following components for forming a conductive elastic blade was kneaded with two rolls, and then aged for about 4 hours at 150°C for 710 minutes. Press molded under the conditions of
It was fixed and held by holding members +5A and 16A to form conductive blades 15 and 16.

Miracene E-34 (TSEIC: USA) 10
0 parts by weight Zinc stearate 0.5 Dicumyl peroxide 5 Carbon black
15〃Activated carbon powder
10 (Experimental results for conductive elastic blades 15 and 16) The photoreceptor, applied voltage, and evaluation criteria used in the experiment were the same as those in the specific examples (a) and (b). In addition, in this experimental example, continuous image acquisition and image quality evaluation were performed using a plain paper copying machine equipped with the conductive elastic blade shown in each of the above specific examples (g) and (h).The results are shown in Table (2). It is as follows. Note that, as a comparative example, evaluation was also conducted in the case where the conductive elastic blades 15 and 16 were not provided.

(Table 2) ◎ Very good resolution ○ Good resolution △ Slightly poor resolution × Not resolved at all Similar to the above table (1), specific examples after 10,000 cycles ( g)
, (h), there is no image blurring in a high temperature and humid environment, but it can be seen that image blurring occurs in the case of the comparative example.

Next, as the materials with high catalytic activity, there are various metal powders, metal oxide powders, etc. formed of particles, and typical examples include N i , P t , P d , A
There are G, Au, etc. A specific example (j) using no metal powder and a specific example (j) using metal powder will be shown below.

(i) After kneading a mixture consisting of the following forming components of a conductive elastic blade using two rolls in a sheet mold of 30 x 3] 8 x 3 (mm), apply the same method as in (g) above to 100 parts by weight of the mixture. Add 1.5 parts by weight of crosslinking agent,
Press molding was carried out under the conditions of secondary vulcanization at 170° C. for 710 minutes (120 kg/d) and secondary vulcanization at 200° C. for 74 hours, and fixed and held by holding members 15A and 16A to form a conductive elastic blade.

Methyl vinyl polysiloxane 100 parts by weight Carbon (Ketcheng Black EC) 8 If dry silica (Aerosil: R972) 15 n Quartz
20〃(j) Metal powder Nj, PL, Pd as the forming component (i) of the conductive elastic blade
, Ag, or Au (10 parts by weight). As a representative example, the case of N1 powder will be shown, but since the same applies to P L -Au powder, these will be omitted.

Methylvinylpolysiloxane 100 parts by weight Carbon (Ketcheng Black EC) 8N1 powder (PL, P
d, Ag, Au powder replaces N1 powder) 10 nol Dry silica (Aerosil: R972) 15
/'Quartz 20 u(
Experimental results of conductive elastic blade mixed with metal powder) The photoreceptor, applied voltage, and evaluation criteria used in the experiment are as in the above specific example (a).
, is the same as (b). This experimental example is based on each of the above specific examples (1).
) and (J), continuous image collection and image quality evaluation were performed using plain paper copying machines equipped with conductive elastic blades, and the results were the same as those in Table (1) above. Note that, as a comparative example, evaluation was also conducted in the case where the conductive elastic blades 15 and 16 were not arranged.

FIG. 5 shows a fourth embodiment of an electrically conductive elastic roller 17, 18 to which positive and negative voltages (direct current or alternating) are applied.

The constituent materials of the conductive elastic rollers 17 and 18 are as follows:
This is similar to the conductive elastic blade described in the third embodiment shown in FIG. 4 above. Therefore, the forming components of the specific example (k) are the same as those of the specific example (g), but the forming method of the specific example (k) (1) is carried out as follows.

(k) The conductive elastic roller forming component was applied onto a stainless steel core metal (6 diameter) that had been previously coated with a conductive primer, and the primary vulcanization was performed at 170°C for 710 minutes (120 kg/cn), and the secondary vulcanization was performed at 200°C. Press molded under the conditions of ℃ / 4 hours, wall thickness 6
A conductive elastic roller of mm was formed.

(1) The same core metal as in the above specific example (k) is treated with carbon powder to make it conductive, and activated carbon powder is added in an amount of 5 parts by weight based on the total weight.
A conductive elastic roller was formed from urethane foam with a wall thickness of 6M containing

Further, the experimental results of the above specific examples (k) and (1) were similar to those of the above specific examples (g) and (h) (Table 2 above). Note that the photoreceptor, applied voltage, and evaluation criteria used in the experiment were the same as those in the specific examples (a) and (b). Furthermore, in this experimental example, continuous image collection and evaluation of image quality were performed using a plain paper copying machine equipped with a conductive roller similar to the above specific examples (k) and (1).

Next, in the fourth embodiment as well, the third embodiment (fourth embodiment)
Examples of materials with high catalytic activity shown in Fig.) include various metal powders formed from particles, metal oxide powders, etc., such as Ni, P
t, Pd, Ag, Au, etc. are used.

Specific examples include a specific example (m) having the same forming components as the above (i) in which the metal powder is not used, and the above (j) in which the metal powder is used.
) and Example (n) having the same forming components are shown in Table (1) above.

The photoreceptor, applied voltage, and evaluation criteria used in the second experiment were the same as those in the specific examples (a) and (b). In this experimental example, continuous image collection and evaluation of image quality were performed using a plain paper copying machine equipped with the conductive elastic rollers shown in the above specific examples (m) and (n). Also, as a comparative example, conductive elastic roller 17.1
At the same time, we are also evaluating the case where 8 is not placed.

(Effects of the Invention) As explained above, the present invention brings a pair of conductive members into contact with the surface of a photoreceptor, and applies a positive or negative voltage to each of the pair of conductive members, or applies a positive or negative voltage to only one of the pair. ,
Alternatively, by applying a negative voltage, the ionic hydrophilic substance adhering to the surface of the photoreceptor is removed, making it possible to maintain stable high image quality over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing a specific example of the first embodiment, and FIGS. 3 to 5 are diagrams showing a second to fourth embodiment of the present invention. FIG. 6, which is a diagram showing each specific example, is a schematic configuration diagram of an image forming apparatus using an electrophotographic method. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 2...Charging charger 3 n tip, 4...Developing device, 5...Transfer charger,
6... Separation charger 7... Cleaning device,
8. Static elimination lamp, 9. Copy paper, 10
... Fixing device, jl... Conductive felt-like structure, 12... Conductive brush-like structure, 13.14...
・Magnetic brush, +3A, 14A... Magnetic brush unit, 13R, 14R... Sleeve roller, 1
5.16...Elastic blade, +5A. 16A... Holding member, 17.18... Elastic roller. Figure 1 Figure 2 (a) Figure 2 (b) Figure 3 L Figure 4 Figure 5 Giant

Claims (2)

[Claims] (1) In an electrophotographic image forming apparatus, a pair of conductive members is brought into contact with the surface of a photoreceptor, and the pair of conductive members is applied with a positive voltage or a negative voltage, respectively, or only one of the pair is applied with a positive or negative voltage. Alternatively, an image forming apparatus characterized in that a hydrophilic substance adhering to the surface of the photoreceptor is removed by applying a negative voltage. (2) The image according to claim (1), wherein the conductive member that contacts the surface of the photoreceptor is composed of a felt-like or brush-like structure, a magnetic brush, an elastic blade, an elastic roller, etc. Forming device.