JP5471609B2 - Image forming method and image forming apparatus capable of executing the method - Google Patents

Description

  The present invention relates to an image forming method using an image forming apparatus such as a copying machine using toner, and to an image forming apparatus capable of executing such an image forming method.

Conventionally, in an electrophotographic process in a copying machine or the like, an image is formed by the following steps (1) to (5).
(1) Charging, (2) Exposure (writing), (3) Toner development, (4) Toner transfer, (5) Toner fixing Examples of such inventions are known.
On the other hand, Patent Document 6 discloses an invention in which the charging step (1) is omitted in steps (1) to (5) of the above-described electrophotographic process. This is because an image carrier having a structure in which a hole transport layer containing at least a hole transport material and a charge generation layer are sequentially laminated on a conductive support, and applying a positive bias simultaneously with light irradiation, a latent image is obtained. It is characterized by forming. This eliminates the charging step that accompanies the discharge that generates ozone and NOx products.

  However, in the method disclosed in this publication, the optical writing mechanism is complicated at the same time as bias application, and there is a possibility that the area around the electrophotographic process becomes large. Also, when an external bias is applied, if a foreign substance such as toner, developer, paper dust, or the like is interposed between the image carrier and the external bias application member, the bias application to the image carrier will be uneven and density unevenness, etc. There is a risk of problems.

  The present invention provides an image forming method capable of omitting a charging step that causes generation of ozone, nitrogen oxides, and the like, and an image forming apparatus capable of forming an electrostatic latent image with a large potential contrast. It is aimed.

As a result of intensive studies, the present inventors have found that the object can be achieved by means for solving the problems shown in the following (1) to (5), and have accomplished the present invention.
(1) An image carrier having a structure in which at least a photosensitive layer, and an upper electrode having a portion covering and not covering the photosensitive layer are sequentially laminated on a conductive support, and at least a latent image forming portion; An image forming method using an image forming apparatus having a toner developing unit, a transfer unit, and a cleaning unit, wherein the latent image forming unit applies a bias to the upper electrode during irradiation of latent image forming light. Thus, a latent image is formed, and after the latent image is formed, the toner developing unit supplies toner to the surface of the image carrier and develops it, and the transfer unit transfers the developed toner image to the material to be transferred. And the cleaning unit applies a bias to the upper electrode of the image carrier to remove toner remaining on the image carrier after transfer.
(2) In the image forming method described in (1), the toner is removed by applying a DC bias to the upper electrode.
(3) In the image forming method described in (1), the toner is removed by applying an AC bias to the upper electrode of the image carrier.
(4) In the image forming method described in (1), the toner is removed by applying an AC bias superimposed on a DC bias to the upper electrode of the image carrier.
(5) An image forming apparatus capable of executing the image forming method according to any one of (1) to (4), wherein an image carrier, a latent image forming unit, a toner developing unit, a transfer unit, a cleaning unit, The image bearing member has a structure in which at least a photosensitive layer and an upper electrode having a portion covering and not covering the photosensitive layer are sequentially stacked.

  The present invention eliminates a charging process that causes generation of ozone, nitrogen oxides, etc., is small in size, has little potential unevenness even in long-term use, and performs an image forming method for forming a direct latent image with improved cleaning performance A possible image forming apparatus can be provided.

It is explanatory sectional drawing which shows an example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is explanatory sectional drawing which shows another example of a structure of the image carrier of this invention. It is a figure which shows the mechanism of electrostatic latent image formation of this invention. 1 is a schematic diagram illustrating an image forming apparatus of the present invention. It is explanatory drawing which shows the specific example of the plasma CVD apparatus used when forming the protective layer which consists of diamond-like carbon or an amorphous carbon structure.

The present invention relates to an image carrier having a structure in which at least a photosensitive layer and an upper electrode having a portion covering and not covering the photosensitive layer are sequentially laminated on a conductive support, and at least a latent image forming portion. And an image forming apparatus having a toner developing section, a transfer section, and a cleaning section, wherein the latent image forming section has a bias applied to the upper electrode when the latent image forming light is irradiated. A latent image is formed by application, and after the latent image is formed, the toner developing unit supplies the toner to the surface of the image carrier and develops it, and the transfer unit transfers the developed toner to the material to be transferred. The cleaning unit is characterized by an image forming method in which a bias is applied to the upper electrode of the image carrier to remove toner remaining on the image carrier after transfer.
By using such an image carrier as an image bearing member and an image forming process, an image for forming an electrostatic latent image with improved toner cleaning characteristics by eliminating a charging process that causes generation of ozone, nitrogen oxides, and the like. An image forming method that simplifies the process around the support can be provided.

First, a configuration example of an image carrier used in the image forming method of the present invention will be described.
FIG. 1 is a diagram showing a basic configuration example of an image carrier used in the image forming method of the present invention. 1 is a conductive support, 2 is a photosensitive layer, and 3 is an electrode. FIG. 1A is a top view of a photoconductor as an image carrier, and FIG. 1B is a cross-sectional view of its side. As shown in FIG. 1B, the image carrier used in the image forming method of the present invention has a structure in which a photosensitive layer 2 and an electrode 3 are sequentially laminated on a conductive support 1. 2A and 2B are diagrams showing a configuration example of another image carrier used in the present invention. FIG. 2A is a top view of a photoconductor as an image carrier, and FIG. 2B is a side view thereof. FIG. The configuration example of the image carrier shown in FIG. 2B has a structure in which a photosensitive layer 2, a charge holding layer 4, and an electrode 3 are sequentially laminated on a conductive support 1. 3A and 3B are diagrams showing a configuration example of another image carrier of the present invention, in which FIG. 3A is a top view of a photoconductor as an image carrier, and FIG. It is sectional drawing. In this figure, a photosensitive layer 2 and an electrode (striped electrode) 3 are sequentially laminated on a conductive support 1. FIG. 4 is a side cross-sectional view showing still another structural example of an image carrier used in the present invention. In this figure, a photosensitive layer 2, a charge holding layer 4, and an electrode (striped electrode) 3 are sequentially laminated on a conductive support 1. FIG. 5 is a side cross-sectional view showing a configuration example of still another image carrier used in the present invention. In this figure, a photosensitive layer 2 and electrodes (lattice electrodes) 3 are sequentially laminated on a conductive support 1. FIG. 6 is a side sectional view showing still another structural example of an image carrier used in the present invention. In this figure, a photosensitive layer 2, an electrode (lattice electrode) 3, and a protective layer 5 are sequentially laminated on a conductive support 1. FIG. 7 is a side cross-sectional view showing still another structural example of an image carrier used in the present invention. In this figure, a photosensitive layer 2, a charge holding layer 4, an electrode 3 and a protective layer 5 are sequentially laminated on a conductive support 1. FIG. 8 is a side cross-sectional view showing still another structural example of an image carrier used in the present invention. In this figure, a structure in which a charge transport layer 2a, a charge generation layer 2b, an electrode 3 and a protective layer 5 are sequentially laminated on a conductive support 1 is shown. FIG. 9 is a diagram showing a configuration example of still another image carrier used in the present invention. In this figure, the structure has a structure in which a charge transport layer 2a, a charge generation layer 2b, a charge retention layer 4 and an electrode 3 are sequentially laminated on a conductive support 1. FIG. 10 is a side cross-sectional view showing a configuration example of still another image carrier used in the present invention. In this figure, a charge generation layer 2b, a charge transport layer 2a, and an electrode 3 are sequentially laminated on a conductive support 1. FIG. 11 is a side cross-sectional view showing a configuration example of still another image carrier used in the present invention. In this figure, the structure has a structure in which a charge generation layer 2b, a charge transport layer 2a, a charge holding layer 4, and an electrode 3 are sequentially laminated on a conductive support 1.

FIG. 12 is a diagram showing an image forming mechanism in the image forming method.
As shown in FIG. 12A, in the present invention, optical writing is performed from the surface of the image carrier while applying a positive bias to the upper electrode of the image carrier. As shown in FIG. 12 (B), the photocarrier generated by exposure is separated into holes and electrons, and according to the electric field formed by the upper electrode, electrons are conducted to the image carrier surface side and holes are conducted. Move to the sex support. Thereafter, as shown in FIG. 12C, when the bias application to the upper electrode is stopped and the float state or the ground state is reached, electrons remain in a portion not covered with the upper electrode, and an electrostatic latent image is formed. Is done.

Next, the image forming method and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 13 is an example of a schematic diagram for explaining the image forming apparatus of the present invention.
(I) A bias is applied to the upper electrode of the image carrier 6, and optical writing is performed by the exposure unit 7. Even after optical writing, a bias is applied to the image carrier 6 to form an electrostatic latent image.
(II) Bias application to the image carrier 6 is stopped, and development is performed with toner in the developing unit (toner developing unit) 8.
(III) The toner image developed on the image carrier 6 is transferred to the transfer material P by the transfer unit 9.
(IV) The toner remaining on the surface of the image carrier 6 is biased by the cleaning unit 10 to the upper electrode of the image carrier 6, the cleaning blade and the brush are brought into contact with each other, the residual toner is removed, and the surface of the image carrier 6 Is removed by the charge removal unit 11.
At this time, a DC bias having the same polarity as that of the toner can be applied to the upper electrode. By this bias application, the toner held on the surface of the image carrier by electrostatic force is easily detached from the surface of the image carrier, and the toner cleaning property is improved.

In general, the DC bias is preferably a bias having a potential of 5 V or more and 100 V or less having the same polarity as that of the polar toner (polarity applied in the developing unit).
Furthermore, it is preferable to apply an AC bias to the upper electrode. In this case, not only the normal polarity toner remaining on the surface of the image carrier but also the slightly reverse polarity toner can be easily cleaned simultaneously. As the AC bias in this case, Vpp is preferably 100 V to 500 V, and the frequency is preferably 0.5 to 2.0 kHz.
Further, it is preferable to apply a DC bias and an AC bias in a superimposed manner. The DC bias component in this case is a bias of 5V to 100V having the same polarity as that of the normal polarity toner, and the AC bias component preferably has a Vpp of 100V to 500V and a frequency of 0.5 to 2.0 kHz.

Hereinafter, the image carrier used in the present invention will be described in detail.
The image carrier used in the present invention has a structure in which at least a photosensitive layer, an upper electrode having a portion covering the photosensitive layer and an uncoated portion, and a surface protective layer are sequentially laminated on a conductive support. Any other layer may be combined arbitrarily.

<About conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. After metal oxide is deposited or sputtered, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes that have been subjected to surface treatment such as cutting, super-finishing, and polishing can be used. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.
In addition, the conductive support dispersed in an appropriate binder resin on the support can be used as the conductive support of the present invention.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned. The binder resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as resins, urethane resins, phenol resins, and alkyd resins. Such a conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support of the present invention.

<About photosensitive layer>
Next, the photosensitive layer will be described. The photosensitive layer may have a laminated structure or a single layer structure.
In the case of a laminated structure, the photosensitive layer is composed of a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. In the case of a single layer structure, the photosensitive layer is a layer having a charge generation function and a charge transport function at the same time.
Hereinafter, each of the photosensitive layer having a laminated structure and the photosensitive layer having a single layer structure will be described.

<Single photosensitive layer>
A photosensitive layer having a single layer structure is a layer having both a charge generation function and a charge transport function. The photosensitive layer can be formed by dissolving or dispersing a charge generation material having a charge generation function, a charge transport material having a charge transport function, and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, antioxidant, a plasticizer, a leveling agent, etc. can also be added as needed.

As the charge generation material, inorganic materials and organic materials can be used.
Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, amorphous silicon, and the like. In amorphous silicon, dangling bonds terminated with hydrogen atoms or halogen atoms, or doped with boron atoms, phosphorus atoms or the like are preferably used.

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

Examples of the charge transport material include a hole transport material and an electron transport material.
Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.

Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
Moreover, antioxidant, a plasticizer, and a leveling agent can also be added as needed.

Examples of the method for producing the photosensitive layer include dip coating, spray coating, bead coating, and ring coating. The coating liquid used for these is the above-mentioned inorganic or organic charge generating material, together with a binder resin if necessary, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole. Using a solvent such as xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc., disperse with a ball mill, attritor, sand mill, bead mill, etc., and dilute the dispersion appropriately to prepare a coating solution. It can be formed by applying a liquid and drying.
The film thickness of the photosensitive layer is suitably about 5 to 50 μm, preferably about 10 to 35 μm.
The charge generation material contained in the photosensitive layer is preferably 1 to 30% by weight based on the total amount of the photosensitive layer, the binder resin contained in the photosensitive layer is 20 to 80% by weight, and the charge transport material is 10 to 70% by weight. Is used satisfactorily.

<Photosensitive layer having a laminated structure>
(Charge generation layer)
The charge generation layer is a layer mainly composed of a charge generation material having a charge generation function, and the above-described binder resin can be used in combination as necessary. As the charge generation substance, the above-described inorganic materials and organic materials can be used. Moreover, the above-mentioned plasticizer and leveling agent can be added if necessary.
As a method for forming the charge generation layer, a vacuum thin film preparation method, a dip coating method from a solution dispersion system, a spray coating, a bead coating, a ring coating method, or the like can be used.
As the vacuum thin film manufacturing method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

(Charge transport layer)
The charge transport layer is a layer mainly composed of a charge transport material having a charge transport function and a binder resin. As the charge transport material, the above-described hole transport material and electron transport material can be used, and as the binder resin, the above-described binder resin can be used. Moreover, the above-mentioned antioxidant, a plasticizer, and a leveling agent can also be added as needed.
The charge transport layer is preferably capable of transporting a bipolar charge. In this case, the hole transport material and the electron transport material are both contained in the binder resin.
As a method for forming the charge transport layer, a dip coating method, spray coating, bead coating, ring coating method, or the like can be used.
The thickness of the charge transport layer is suitably about 5 to 50 μm, preferably about 10 to 35 μm.
The charge generation layer and the charge transport layer may be laminated on the conductive support in the order of the charge generation layer and the charge transport layer, or may be laminated in the order of the charge transport layer and the charge generation layer.

<Upper electrode>
The upper electrode used in the present invention is a layer that forms an electric field on the photosensitive layer by applying a bias. The material of the upper electrode is not particularly limited as long as it is a conductive material, such as platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony, lead, tantalum, indium, aluminum, zinc, magnesium, and the like. These alloys, conductive metal oxides such as indium and tin oxide, or inorganic and organic semiconductors whose conductivity has been improved by doping, such as silicon single crystal, polysilicon, amorphous silicon, germanium, graphite, polyacetylene, Examples include polyparaphenylene, polythiophene, polypyrrole, polyaniline, polythienylene vinylene, polyparaphenylene vinylene, a complex of polyethylenedioxythiophene and polystyrene sulfonic acid, and the like.

  As a method for forming an electrode, a method of forming an electrode using a known photolithographic method or a lift-off method, using a conductive thin film formed by a method such as vapor deposition or sputtering using the above materials as a raw material, a metal such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like on a foil. Alternatively, the conductive polymer solution or dispersion, or the conductive fine particle dispersion may be directly patterned by ink jetting, or may be formed from the coating film by lithography, laser ablation, or the like. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste, or the like by a printing method such as a relief printing plate, an intaglio printing plate, a planographic printing plate or a screen printing method can also be used.

The upper electrode used in the present invention does not completely cover the surface of the photosensitive layer, but has a coated part and an uncoated part. The coverage of the part covered with respect to the whole surface area is about 5 to 80%, Preferably it is about 10 to 50%. The electrode shape covered may be an irregular shape, but is preferably a striped shape, more preferably a lattice shape. In the case of a striped electrode, the interelectrode distance is 5 μm to 100 μm, preferably 5 to 20 μm. The same applies to the case of the grid-like electrode, and the interelectrode distance between the parallel electrodes is 5 μm to 100 μm, preferably 5 to 20 μm. The film thickness of these electrodes is 0.01 μm to 5.00 μm, preferably 0.02 to 0.50 μm.
The bias can be applied to the upper electrode at the end of the image carrier, and the bias is supplied by pressing a conductive roller or conductive brush.

<Charge retention layer>
The charge holding layer provided on the photosensitive layer is provided for the purpose of efficiently holding charges when forming an electrostatic latent image. The charge holding layer mentioned here preferably has no charge transporting ability, but may have a lower charge transporting ability than the photosensitive layer and the charge transporting layer described above.
For the charge retention layer, the above-described binder resin material for the photosensitive layer can be used. Moreover, antioxidant, a plasticizer, and a leveling agent can also be added as needed.
The thickness of the charge retention layer is suitably about 0.2 to 5.0 μm, preferably about 0.5 to 2.5 μm.

<Protective layer>
The protective layer provided on the upper electrode is provided for the purpose of protecting the upper electrode. The protective layer does not directly affect electrostatic latent image formation. However, this image carrier cannot form a basic electrostatic latent image when the upper electrode disappears due to a mechanical hazard such as a developing unit, a transfer unit, or a cleaning unit. The upper electrode on the current photosensitive layer is weak against these mechanical hazards, and it is necessary to provide a protective layer for practical use.

  As the protective layer, the same binder resin material as that of the charge retention layer can be used. Preferably, a film using a three-dimensional cross-linked resin such as urethane resin or acrylic resin, a film in which a filler is dispersed in the resin, or a film having a diamond-like carbon or amorphous carbon structure is used.

In particular, a protective layer having a diamond-like carbon or amorphous carbon structure is preferable. The protective layer having a diamond-like carbon or amorphous carbon structure preferably has a C—C bond similar to diamond having SP ³ orbitals. A film having a structure similar to that of graphite having SP ² orbits or an amorphous film may be used.
The protective layer having a diamond-like carbon or amorphous carbon structure is an additive element such as nitrogen, fluorine, boron, phosphorus, chlorine, bromine, iodine for resistance control, light transmission control, mechanical property control, etc. May be contained.

When producing a protective layer having a diamond-like carbon or amorphous carbon structure, a carrier gas such as H ₂ or Ar is used with a hydrocarbon gas (methane, ethane, ethylene, acetylene, etc.) as a main material. Furthermore, any gas can be used for supplying the additive element as long as it can be vaporized under reduced pressure or can be vaporized by heating. For example, NH ₃ , N ₂ or the like is used as a gas for supplying nitrogen, C ₂ F ₆ , CH ₃ F or the like is used as a gas for supplying fluorine, B ₂ H ₆ or the like is used as a gas for supplying boron, phosphorus PH ₃ or the like is used as the gas supplying chlorine, CH ₃ Cl, CH ₂ Cl ₂ , CHCl ₃ , CCl ₄ or the like is used as the gas supplying chlorine, and CH ₃ Br or the like is used as the gas supplying bromine. As the gas for supplying iodine, CH ₃ I or the like can be used. Further, as a gas for supplying a plurality of additive elements, NF ₃ , BCl ₃ , BBr, BF ₃ , PF ₃ , PCl ₃ or the like is used. Using the gas as described above, it is formed by a plasma CVD method, a glow discharge decomposition method, a photo CVD method or the like, a sputtering method using graphite or the like as a target, or the like. Although the film forming method is not particularly limited, as a method for forming a carbon-based film having good characteristics as a protective layer, the film is formed with a sputtering effect while being a plasma CVD method. A method (Japanese Patent Laid-Open No. 58-49609) is known.

  In the method of forming a protective layer mainly composed of carbon using the plasma CVD method, it is not necessary to heat the support in particular, and a film can be formed at a low temperature of about 150 ° C. or lower. There is also an advantage that there is no problem when the protective layer is formed on the layer.

  The thickness of the protective layer having a diamond-like carbon or amorphous carbon structure is desirably 0.5 μm or more and 3.0 μm or less.

  In particular, a protective layer in which a filler is dispersed in a resin is preferable. Fillers added to the protective layer include organic and inorganic fillers.

  Examples of organic fillers include fluororesin fillers such as polytetrafluoroethylene, silicone resin fillers, fillers mainly composed of carbon, and inorganic filler materials include metals such as copper, tin, aluminum, and indium. Powder, silicon oxide, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, tin-doped metal oxide such as indium oxide, inorganic such as potassium titanate Materials. In particular, it is advantageous to use an inorganic material or a filler material mainly composed of carbon. In particular, metal oxides are good for inorganic materials, and silicon oxide, aluminum oxide, titanium oxide, and the like can be used effectively. Furthermore, diamond filler can be used effectively for fillers mainly composed of carbon.

  The higher the filler concentration of the protective layer, the better the abrasion resistance, but the better. However, the writing light transmittance is lowered, which may cause side effects. Therefore, it is approximately 50% by weight or less, preferably 30% by weight or less, based on the total solid content. The lower limit is usually 5% by weight.

  The film thickness of the protective layer in which the filler is dispersed in the resin is suitably from 0.5 μm to 10 μm, and preferably from 1.0 μm to 6.0 μm.

<Underlayer>
In the image carrier of the present invention, an undercoat layer can be provided between the conductive support and the photosensitive layer for the purpose of adhesion to the photosensitive layer and prevention of moire. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide filler such as titanium oxide, silicon oxide, aluminum oxide, zirconium oxide, tin oxide, or indium oxide may be added.

The undercoat layer can be formed using an appropriate solvent and coating method as in the above-described layers. Furthermore, in this invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, etc. can also be used as an undercoat layer. In addition, the undercoat layer is formed by anodizing Al ₂ O ₃ , organic materials such as polyparaxylylene (parylene), and inorganic materials such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, and CeO _2. Can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0.1 to 5.0 μm.

  By adopting the image forming method as described above, there is no discharge product such as NOx and ozone generated in the charging process of the conventional electrophotographic process, and there is no charging member in the charging process. It is possible to provide an image forming method excellent in long-term image stability.

  Such an image forming method may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. The process cartridge is an apparatus (part) that contains an image carrier and includes a latent image forming unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and the like.

  By using such an image forming method, it is possible to eliminate a charging step accompanied by discharge that generates ozone and NOx products, and to simplify the latent image forming step. Compared with Patent Document 6, the bias application simultaneous bias supply mechanism can be made smaller. Further, when bias is applied from the outside, bias application becomes non-uniform due to the presence of foreign matter such as toner, developer, paper dust, etc. between the image carrier and the external bias application member, resulting in density unevenness. However, in the present invention, by using the above-described image carrier, foreign matter adhesion between the electrode and the lower layers does not occur, and uniform bias application can always be performed. There is no adverse effect such as. Further, by applying a bias to the image carrier at the cleaning unit, the cleaning property of the residual toner from the image carrier is improved, and abnormal images are reduced.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is limited to these Examples, a comparative example, etc., and is not interpreted. In addition, the part described below means a weight part.
<< Production Example 1 of Image Carrier (Photoconductor) 1: Production Example 1 >>
[Substrate]
φ100mm, length 360mm aluminum drum [photosensitive layer]
A coating solution shown below was applied onto the substrate to form a photosensitive layer.
(Coating fluid)
Bisphenol Z-type polycarbonate (Panlite TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts

Oxotitanium phthalocyanine pigment 1 part Tetrahydrofuran 80 parts (film forming conditions)
Coating method: Dipping Film thickness: 30μm
Drying conditions: Heat drying (130 ° C., 20 minutes)

[Charge retention layer]
The following coating solution was applied onto the drum provided with the photosensitive layer to form a charge retention layer.
(Coating fluid)
Copolymer nylon resin (CM8000: manufactured by Toray Industries, Inc.) 4.5 parts Methyl alcohol 80 parts Isobutyl alcohol 15.5 parts (film forming conditions)
Coating method: Dipping Film thickness: 2.0μm
Drying conditions: Heat drying (100 ° C., 20 minutes)
[electrode]
The following electrodes were formed on a drum provided with a charge retention layer.
Film formation method: Vacuum deposition method (after deposition, processing with excimer laser)
Deposition source: Aluminum electrode pattern: Lattice electrode (distance between electrodes 25 μm, electrode width 20 μm)

[Protective layer: Protective layer 1]
A charge holding layer was formed by coating on a drum provided with a photosensitive layer, a charge holding layer, and an electrode using the following coating liquid material.
(Coating fluid material)
Isocyanate (Takenate D140N: made by Mitsui Takeda Chemical)
Polyol (LZR170: manufactured by Fujikura Kasei Co., Ltd.)
A mixture of the above isocyanate and polyol so that the equivalent ratio of NCO / OH is 1.0 10 parts Acetone 40 parts Cellosolve acetate 40 parts Methyl isobutyl ketone 10 parts (film forming conditions)
Coating method: Spray Film thickness: 2.0μm
Drying conditions: Heat drying (100 ° C., 20 minutes)

<< Image Carrier (Photosensitive Member) Production Example 2: Production Example 2 >>
An image carrier was produced in the same manner as in Photoconductor Production Example 1 (Production Example 1) except that the film formation conditions for the protective layer of the image carrier were changed to the film formation conditions shown below.
(Film forming conditions of protective layer 2)
The substrate was set in the plasma CVD apparatus shown in FIG. 14 to form a protective layer. In FIG. 14, reference numeral 107 denotes a vacuum chamber of a plasma CVD apparatus, which is partitioned from a load / unload spare chamber 117 by a gate valve 109. The inside of the vacuum chamber 107 is evacuated by an exhaust system 120 (comprising a pressure adjusting valve 121, a turbo molecular pump 122, and a rotary pump 123), and is kept at a constant pressure.
A reaction tank is provided in the vacuum tank 107. Reference numeral 130 denotes a gas line introduced into the reaction tank 150, to which various material gas containers are connected. Each is introduced into the reaction tank 150 from the nozzle 125 via the flow meter 129.
In the frame-like structure 102, a substrate 101 (101-1, 101-2, ..., 101-n, ...) on which the photosensitive layer is formed is disposed. Each of the supports is disposed as a third electrode as will be described later. For the electrodes 103 and 113, a pair of power sources 115 (115-1 and 115-2) for applying a first alternating voltage is prepared. The frequency of the first alternating voltage is 1 to 100 MHz. These power sources are connected to matching transformers 116-1 and 116-2, respectively. The phase in the matching transformer is adjusted by the phase adjuster 126 and can be supplied with a shift of 180 ° or 0 ° from each other. That is, it has a symmetrical or in-phase output. The one end 104 and the other end 114 of the match transformer are connected to the first and second electrodes 103 and 113, respectively. Further, the output-side midpoint 105 of the transformer is held at the ground level. Further, a second alternating voltage between the midpoint 105 and the third electrode, that is, the base 101 (101-1, 101-2,..., 101-n) or the holder 102 electrically connected thereto. A power source 119 is applied to apply. The frequency of the second alternating voltage is 1 to 500 KHz. The output of the first alternating voltage applied to the first and second electrodes is 0.1 to 1 kW at a frequency of 13.56 MHz, and the second alternating voltage applied to the third electrode, that is, the support. Is about 100 W for a frequency of 150 KHz.

A protective layer was formed under the following conditions.
C ₂ H ₄ flow rate: 90 sccm
H ₂ flow rate: 150 sccm
NF ₃ flow rate: 45sccm
Reaction pressure: 0.02 torr
First alternating voltage output: 200W 13.56 MHz
Bias voltage (DC component): -100V
Film thickness: 2.0μm

<< Evaluation equipment and conditions >>
(Machine):
Ricoh Co., Ltd. Imagio MF7070 remodeling machine (latent image forming part)
Writing light: 780 nm LD
Image carrier upper electrode applied bias: + 600V
Bias application time: 60 ms
(Development part)
Development bias: + 250V
Toner: Polyester plus polarity toner (transfer area)
Bias application with reverse polarity to machine standard conditions (cleaning part)
Method: Image carrier bias application blade contact cleaning Blade contact pressure: 20 g / cm
Angle: 78 degrees (cleaning part image carrier upper electrode bias application condition)
Bias condition 1: DC bias + 50V
Bias condition 2: AC bias Vpp 200V, frequency 1.5kHz
Bias condition 3 (superposition of DC and AC): DC bias + 70V
Superimposed AC bias Vpp 150V, frequency 1.5kHz
Bias condition 4: No bias applied (evaluation environment)
Environmental condition 1: Temperature 20 ° C, humidity 65% RH
Environmental condition 2: Temperature 10 ° C, humidity 15% RH
(Conditions for passing paper)
Image: Test chart NO. 3
Paper passing pattern: 5 prints (A3) / job

(Cleaning defect evaluation)
5K sheets (5,000 sheets) and 10K sheets (10,000 sheets) were passed through the difference in image carrier under each of the evaluation conditions of the bias conditions 1 to 4 and the environmental conditions 1 and 2 described above. After completion of the paper passing, whether or not a cleaning failure occurred was evaluated by the following four stages of ○, Δ, ×, and XX by outputting a white image and visually observing it.
◯: Good Δ: Stripe-like cleaning failure ×: Strip-like cleaning failure XX: Entire surface cleaning failure The evaluation results are shown in Table 1. As shown in Table 1, Examples 1 to 3 and Comparative Example 1 are those of Production Example 1 as image carriers, and Examples 4 to 6 and Comparative Example 2 are those of Production Example 2 as image carriers. The bias condition is changed.

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 2a Charge transport layer 2b Charge generation layer 3 Upper electrode 3a Striped electrode 3b Grid-like electrode 4 Charge holding layer 5 Protective layer 6 Image carrier 7 Exposure part 8 Development part 9 Transfer part 10 Cleaning part DESCRIPTION OF SYMBOLS 11 Static elimination part 101-1 to 101-n Support body 102 Frame-like structure 103,113 Electrode 104,114 Matching transformer edge 105 Transformer output side midpoint 107 Vacuum tank 108,118 Hood 109 Gate valve 115 Power supply 116-1 116-2 Matching transformer 117 Spare room for load / unload 119 Power supply 120 Exhaust system 121 Adjustment valve 122 Turbo molecular pump 123 Rotary pump 125 Gas introduction nozzle 126 Phase adjuster 129 Flow meter 130 Gas line 140 Alternate power supply system

Japanese Patent Laid-Open No. 06-003921 JP-A-8-76559 JP-A-9-26681 JP 2001-183853 A Japanese Patent No. 3566275 JP 2007-178816 A

Claims (5)

An image carrier having a structure in which at least a photosensitive layer, and an upper electrode having a portion covering and not covering the photosensitive layer are sequentially laminated on a conductive support, at least a latent image forming portion, and toner development An image forming method using an image forming apparatus having a section, a transfer section, and a cleaning section,
The latent image forming unit forms a latent image by applying a bias to the upper electrode during irradiation of latent image forming light. After the latent image is formed, the toner developing unit transfers toner to the surface of the image carrier. The transfer unit transfers the developed toner to a transfer material, and the cleaning unit applies a bias to the upper electrode of the image carrier to transfer the image to the image carrier. An image forming method comprising removing remaining toner.   The image forming method according to claim 1, wherein the bias applied to the upper electrode of the image carrier is a DC bias.   The image forming method according to claim 1, wherein the bias applied to the upper electrode of the image carrier is an AC bias.   2. The image forming method according to claim 1, wherein the bias applied to the upper electrode of the image carrier is a direct current bias superimposed on an alternating current bias. An image forming apparatus capable of executing the image forming method according to claim 1, comprising an image carrier, a latent image forming unit, a toner developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. ,
An image forming apparatus, wherein the image carrier has a structure in which at least a photosensitive layer and an upper electrode having a portion covering and not covering the photosensitive layer are sequentially laminated.

Images