JP3034256B2 - High resolution electrostatic camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-resolution electrostatic camera which is arranged to face a photoconductor and forms and records an electrostatic latent image by voltage application exposure.

[Conventional technology]

The applicant has already obtained high quality and high resolution for silver halide photography, electrophotography, television photography, television photography using solid-state imaging device (CCD), etc. and the processing steps are simple and long. We propose a recording / reproducing method using a charge storage medium that can store time, and can repeatedly and repeatedly reproduce stored characters, line drawings, images, and luminous intensity (1,0) information with image quality according to the purpose. Yes (Japanese Patent Application No. 63-121592)
issue).

[Problems to be solved by the invention]

By the way, such a charge storage medium can record an electrostatic latent image for a long time, but since the insulating property is high, the latent image cannot be easily erased. Further, if the latent image cannot be easily erased, the advantage of repeatedly using the image for recording / reproduction cannot be utilized.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-resolution electrostatic camera capable of simply and reliably erasing a latent image on a charge storage medium and enabling repeated use of the charge storage medium. And

[Means for solving the problem]

The present invention provides a high-resolution electrostatic camera including a photoreceptor, a charge holding medium disposed opposite to the photoreceptor, means for applying a voltage between the photoreceptor and the charge holding medium, and means for exposing through the photoreceptor. Wherein the latent image is erased by means such as reverse voltage application exposure, uniform exposure, corona charging, heating, ultraviolet irradiation, scanning on the surface of the conductive member, and spraying steam.

[Action]

The present invention relates to a high-resolution electrostatic camera including a photoreceptor, a charge holding medium disposed opposite to the photoreceptor, means for applying a voltage between the photoreceptor and the charge holding medium, and means for exposing through the photoreceptor. Exposure to a charge holding medium by applying a reverse voltage, uniform exposure by applying a voltage of the same or different polarity, exposure of a pattern opposite to that during recording, charge leakage due to heating of the charge holding medium, and charge generated by ultraviolet irradiation This is to erase the latent image on the charge holding medium by utilizing the charge erasure caused by the pattern erasure and the charge leak caused by spraying the current collecting member or conductive vapor. It can be used.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a view for explaining a recording method in the electrostatic image recording / reproducing method of the present invention, wherein 1 is a photosensitive member, 3 is a charge holding medium, 5 is a photoconductive layer support, and 7 is a photosensitive member. Electrode, 9
Denotes a photoconductive layer, 11 denotes an insulating layer, 13 denotes a charge holding medium electrode, 15 denotes an insulating layer support, and 17 denotes a power supply.

FIG. 1 shows an embodiment in which exposure is performed from the photoreceptor 1 side. First, a transparent photoreceptor electrode 7 made of ITO having a thickness of 1000 mm is formed on a photoconductive layer support 5 made of 1 mm thick glass. The photoconductor 1 is formed by forming a photoconductive layer 9 of about 10 μm thereon. The charge holding medium 3 is arranged on the photoconductor 1 with a gap of about 10 μm. The charge holding medium 3 is placed on an insulating layer support 15 made of glass having a thickness of 1 mm.
An Al electrode 13 having a thickness of 0 mm is formed by evaporation, and
In this case, an insulating layer 11 having a thickness of 0 μm is formed.

First, as shown in FIG.
The charge holding medium 3 is set through a gap of about 10 μm,
As shown in FIG. 1 (b), a voltage is applied between the electrodes 7 and 13 by the power supply 17. In a dark place, since the photoconductive layer 9 is a high-resistance body, no change occurs between the electrodes. When light is incident from the photoreceptor 1 side, the photoconductive layer 9 in the portion where the light is incident shows conductivity, and a discharge occurs between the photoconductive layer 9 and the insulating layer 11.
The electric charge is accumulated.

When the exposure is completed, a voltage is applied as shown in FIG.
Turn off, and then take out the charge holding medium 3 as shown in FIG. 1 (d) to complete the formation of the electrostatic latent image.

The photoconductor 1 and the charge holding medium 3 may be of a contact type instead of a non-contact type as described above. In the case of the contact type, a positive or negative charge is applied to the exposed portion of the photoconductive layer 9 from the photoconductor electrode 7 side. Charges are injected, and the charges are drawn by the electrode 13 on the charge holding medium 3 side, pass through the photoconductive layer 9, and stop moving when reaching the surface of the insulating layer 11. Is done. Then, when the photoconductor 1 and the charge holding medium 3 are separated, the insulating layer
11 are separated while keeping the charge.

When this recording method is a planar analog recording, high resolution can be obtained in the same manner as the silver halide photography, and an insulating layer to be formed is formed.
Although the surface charge on 11 is exposed to the air environment, the air has a good insulating performance, so it is stored for a long time without discharging regardless of the light place and the dark place.

The charge storage period on the insulating layer 11 is determined by the properties of the insulator, and is affected by the charge trapping characteristics of the insulator in addition to the insulating properties of air. In the above description, charges are described as surface charges.Injected charges may simply accumulate on the surface, and microscopically penetrate into the vicinity of the insulator surface, and electrons or electrons enter the structure of the substance. Since the holes may be trapped, long-term storage is performed. Further, the surface of the insulating layer 11 may be covered with an insulating film or the like and stored in order to prevent physical damage to the charge holding medium or discharge when the humidity is high.

Hereinafter, constituent materials of the photoreceptor and the charge holding medium used in the present invention will be described.

The material and thickness of the photoconductive layer support 5 are not particularly limited as long as the photoconductive layer support 5 has a certain strength capable of supporting the photoreceptor. For example, a flexible plastic film, metal foil, paper, or the like may be used. Alternatively, a rigid body such as a glass, a plastic sheet, or a metal plate (which can also serve as an electrode) is used. However, when used in a device that records information by irradiating light from the photoconductor side, it is naturally necessary to have the property of transmitting that light.For example, when using natural light as incident light and using it in a camera that enters from the photoconductor side Has a thickness of 1m
A transparent glass plate of about m or a plastic film or sheet is used.

The photoreceptor electrode 7 is formed on the photoconductive layer support 5 except when a metal is used for the photoconductive layer support 5, and the material thereof is as long as the specific resistance value is 10 ⁶ Ω · cm or less. There is no limitation, and an inorganic metal conductive film, an inorganic metal oxide conductive film, or the like can be used.
Such a photoconductor electrode 7 is formed on the photoconductive layer support 5 by vapor deposition, sputtering, CVD, coating, plating, dipping, electrolytic polymerization, or the like. The thickness of the electrode must be changed depending on the electrical characteristics of the material constituting the photoreceptor electrode 7 and the applied voltage when recording information. For example, in the case of aluminum, the thickness is about 100 to 3000 °. This photoconductor electrode 7 is also similar to the photoconductive layer support 5,
When the information light needs to be incident, the above-mentioned optical characteristics are required, and for example, the information light is a visible light (400 to 700 nm).
A transparent electrode such as ITO (In ₂ O ₃ —SnO ₂ ), SnO ₂ , or the like, which is formed by sputtering, vapor deposition, or coating a fine powder thereof by ink with a binder, Au, A
Translucent electrode made of l, Ag, Ni, Cr, etc. by evaporation or sputtering, tetracyanoquinodimethane (TCNQ),
An organic transparent electrode or the like with a coating of polyacetylene or the like is used.

When the information light is infrared (700 nm or more) light, the above electrode material can be used. In some cases, a colored visible light absorbing electrode can also be used to cut off visible light.

Further, when the information light is ultraviolet light (400 nm or less), the above-mentioned electrode materials can be basically used, but those in which the electrode substrate material absorbs ultraviolet light (organic polymer materials, soda glass, etc.) are not preferable. A material that transmits ultraviolet light, such as quartz glass, is preferable.

The photoconductive layer 9 is a conductive layer in which photocarriers (electrons and holes) are generated in the irradiated portion when light is irradiated, and the carriers can move in a layer width. In particular, an electric field exists. In this case, the effect is remarkable. The material is composed of an inorganic photoconductive material, an organic photoconductive material, an organic-inorganic hybrid type photoconductive material, or the like.

Hereinafter, a method for forming the photoconductive material and the photoconductive layer will be described.

(A) Inorganic Photoreceptor (Photoconductor) Examples of inorganic photoreceptor materials include amorphous silicon, amorphous selenium, cadmium sulfide, and zinc oxide.

(A) Amorphous silicon photoreceptor As an amorphous silicon photoreceptor, hydrogenated amorphous silicon (a-Si: H) fluorinated amorphous silicon (a-Si: F) Ga, In, Tl, etc. made P-type (hole transport type) by doping. ・ P, Ag, Sb, Bi, etc. made N-type (electron transport type) by doping.

As a method of forming the photoreceptor layer, a silane gas and an impurity gas are introduced into a low vacuum together with a hydrogen gas (10 ^{-2 to 1} Torr).
r), a film is formed by pre-stacking on an electrode substrate heated or not heated by glow discharge, or a thermochemical reaction is formed on a heated electrode substrate, or a solid material is formed by vapor deposition and sputtering. Used as a film, a single layer or a laminate. The film thickness is 1 to 50 μm.

Further, a charge injection preventing layer can be provided on the surface of the photoreceptor electrode 7 in order to prevent charge from being injected from the transparent electrode 7 and being exposed as if it were not exposed. As the charge injection preventing layer, an a-SiN layer, a-SiC layer is formed on one or both of the electrode substrate and the uppermost layer (surface layer) of the photoreceptor by glow discharge, vapor deposition, sputtering or the like.
It is preferable to provide an insulating layer such as a layer, a SiO ₂ layer, and an Al ₂ O ₃ layer. If the insulating layer is too thick, no current will flow when exposed, so it must be at least 1000 ° or less, and preferably about 400-500 ° in consideration of ease of fabrication.

Further, as the charge injection preventing layer, it is preferable to provide a charge transporting layer having a charge transporting ability of a polarity opposite to the polarity of the electrode substrate on the electrode substrate by utilizing a rectifying effect. Is positive, an electron transport layer is provided. For example, a-Si: H doped with boron in Si
(N ⁺ ) enhances the hole transporting property, provides a rectifying effect, and functions as a charge injection preventing layer.

(B) Amorphous selenium photoconductor Amorphous selenium photoconductor includes amorphous selenium (a-Se) amorphous selenium tellurium (a-Se-Fe) amorphous arsenic selenium compound (a-AS ₂ Se ₃ ) amorphous arsenic selenium compound + Te .

This photoreceptor is prepared by vapor deposition and sputtering, and a SiO ₂ , Al ₂ O ₃ , SiC, SiN layer as a charge injection blocking layer is provided on the electrode substrate by vapor deposition, sputtering, glow discharge or the like. Further, the above-mentioned may be combined to form a laminated photoreceptor. The thickness of the photoconductor layer is the same as that of the amorphous silicon photoconductor.

(C) Cadmium sulfide (CdS) This photoreceptor is prepared by coating, vapor deposition, and sputtering. In the case of vapor deposition, solid particles of CdS are placed on a tungsten board and vapor-deposited by resistance heating, or EB
(Electron beam) This is performed by vapor deposition. In the case of sputtering, deposition is performed on a substrate in argon plasma using a CdS target. In this case, CdS is usually deposited in an amorphous state, but a crystalline alignment film (oriented in the film thickness direction) can be obtained by selecting sputtering conditions.
You can also get In the case of coating, CdS particles (particle diameter: 1 to 100 μm) may be dispersed in a binder, and a solvent may be added to coat on a substrate. .

(D) Zinc oxide (Zn O) This photoreceptor is manufactured by a coating method or a CVD method. As the coating method, ZnS particles (particle size 1 to 100
μm) is dispersed in a binder, a solvent is added, and coating is performed on a substrate. In the CVD method, an organic metal such as diethyl zinc or dimethyl zinc and oxygen gas are mixed in a low vacuum (10 ^{-2 to 1} Torr), and a chemical reaction is performed on a heated electrode substrate (150 to 400 ° C.) to oxidize. Deposited as a zinc film. Also in this case, a film oriented in the film thickness direction can be obtained.

(B) Organic Photoreceptor The organic photoreceptor includes a single-layer type photoreceptor and a function-separated type photoreceptor.

(A) Single-layer photoconductor The single-layer photoconductor is composed of a mixture of a charge generating substance and a charge transport substance.

<Charge-generating substance type> It is a substance that absorbs light and easily generates an electric charge.For example, azo pigments, disazo pigments, trisazo pigments, phthalocyanine pigments, perylene pigments, pyrylium dyes,
Cyanine dyes and methine dyes are used.

<Charge transporting substance system> A substance having a good ionized charge transporting property, for example, hydrazone type, pyrazoline type, polyvinyl carbazole type, carbazole type, stilbene type, anthracene type,
There are naphthalene type, tridiphenylmethane type, azine type, amine type, aromatic amine type and the like.

Further, a charge transfer complex may be formed by forming a complex between the charge generation material and the charge transport material.

Normally, a photoreceptor has photosensitivity determined by the light absorption characteristics of a charge generating substance. However, if a charge generating substance and a charge transporting substance are mixed together to form a complex, the light absorption properties change. For example, polyvinyl carbazole (PVK) is an ultraviolet light. Only in the region, trinitrofluorenone (TNF) only feels around 400nm wavelength, but PVK-TNF complex feels up to 650nm wavelength region.

The thickness of such a single-layer type photoreceptor is preferably 10 to 50 μm.

(B) Function-separated type photoreceptor Although the charge generating material easily absorbs light, it has the property of trapping light, and the charge transporting material has good charge transporting properties.
Light absorption characteristics are not good. Therefore, the two are separated so as to sufficiently exhibit their respective characteristics, and the charge generation layer and the charge transport layer are stacked.

<Charge Generating Layer> Examples of the material for forming the charge generating layer include azo-based materials,
Disad, trisazo, phthalocyanine, acid xansen dyes, cyanine, styryl dyes, pyrylium dyes, perylenes, methines, a-Se, a-Si, azurenium salts, squarium salts, and the like.

<Charge transport layer> Examples of the material forming the charge transport layer include hydrazone, pyrazoline, PVK, carbazole, oxazole, triazole, aromatic amine, amine, triphenylmethane, and polycyclic aromatic compounds. Group compounds.

As a method for producing a function-separated type photoreceptor, a charge generating substance is first dissolved in a solvent and applied on an electrode, and then the charge transport layer is dissolved in a solvent and applied to the charge transport layer.
It is preferable that the thickness of the charge transport layer be 0.1 to 10 μm and the thickness of the charge transport layer be 10 to 50 μm.

In addition, in any case of the single-layer type photoreceptor and the function separation type photoreceptor, as a binder, a silicone resin, a styrene-butadiene copolymer resin, an epoxy resin, an acrylic resin,
Saturated or unsaturated polyester resin, polycarbonate resin, polyvinyl acetal resin, phenol resin, polymethyl methacrylate (PMMA) resin, melamine resin,
0.1 to 10 parts of a polyimide resin or the like is added to 1 part of each of the charge generating material and the charge transport material so that the resin can be easily attached. As a coating method, a dipping method, an evaporation method, a sputtering method, or the like can be used.

 Next, the charge injection preventing layer will be described in detail.

The charge injection preventing layer is provided on at least one of both surfaces of the photoconductive layer 9 or on both surfaces, even though the dark current (charge injection from the electrode) when the voltage of the photoconductive layer 9 is applied, that is, not exposed. It can be provided to prevent a phenomenon that charges move in the photosensitive layer as if exposed.

The charge injection preventing layer includes two types, a layer using a so-called tunneling effect and a layer using a rectifying effect. First, in a device utilizing the so-called tunneling effect, current does not flow to the photoconductive layer or the insulating layer surface due to the charge injection preventing layer only by applying a voltage, but when light is incident, it corresponds to an incident portion. In the charge injection preventing layer, a high electric field is applied due to the presence of one of the charges (electrons or holes) generated in the photoconductive layer, causing a tunnel effect and causing a current to flow through the charge injection preventing layer. . Such a charge injection preventing layer is formed of a single layer such as an inorganic insulating film, an organic insulating polymer film, an insulating monomolecular film, or the like, or a single layer thereof. As the inorganic insulating film, for example, As ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , CdS, CaO, CeO ₂ , Cr ₂ O ₃ , CoO,
GeO ₂ , HfO ₂ , Fe ₂ O ₃ , La ₂ O ₃ , MgO, MnO ₂ , Nd ₂ O ₃ , Nb
₂ O ₅ , PbO, Sb ₂ O ₃ , SiO ₂ , SeO ₂ , Ta ₂ O ₅ , TiO ₂ , WO ₃ , V ₂ O
_{5, Y 2 O 5, Y} 2 O 3, ZrO 2, BaTiO 3, Al 2 O 3, Bi 2 TiO 5, CaO-
_{SrO, CaO-Y 2 O 3} , Cr-SiO, LiTaO 3, PbTiO 3, PbZrO 3, Z
rO ₂ -Co, ZrO ₂ -SiO ₂ , AlN, BN, NbN, Si ₃ N ₄ , TaN, Ti
N, VN, ZrN, SiC, TiC, WC, Al ₄ O _{3 and the} like are formed by glow discharge, vapor deposition, sputtering and the like. The thickness of this layer is determined for each material used in consideration of the insulating property for preventing charge injection and the tunnel effect. Next, as the charge injection preventing layer utilizing the rectifying effect, a charge transporting layer having a charge transporting ability having a polarity opposite to the polarity of the electrode substrate is provided using the rectifying effect. That is, such a charge injection preventing layer is formed of an inorganic photoconductive layer, an organic photoconductive layer, and an organic-inorganic hybrid type photoconductive layer, and has a thickness of about 0.1 to 10 μm. Specifically, when the electrode is negative, B, Al, Ga, amorphous silicon photoconductive layer doped with In, etc., amorphous selenium, or oxadiazole, pyrazoline, polyvinylcarbazole, stilbene, anthracene, naphthalene, tridiphenylmethane, Organic photoconductive layer formed by dispersing triphenylmethane, azine, amine, aromatic amine, etc. in a resin. If the electrode is positive, P, N, As,
Amorphous silicon photoconductive layer doped with Sb, Bi, etc.,
Glow discharge, vapor deposition, sputtering, C
It is formed by a method such as VD or coating.

Next, a charge holding medium material and a method for manufacturing the charge holding medium will be described.

The charge holding medium 3 is used together with the photoreceptor 1 to record information as a distribution of electrostatic charges on the surface of the insulating layer 11 constituting the charge holding medium 3 or inside thereof.
The charge holding medium itself is used as a recording medium. Therefore, the shape of the charge holding medium can take various shapes depending on the information to be recorded or the recording method. For example, when used for an electrostatic camera, it becomes a general film (for single frame or continuous frame) shape or disk shape. When digital information or analog information is recorded by a laser or the like, a tape shape or a disk shape is used. Or, it has a sword shape.

The insulating layer support 15 strongly supports the charge holding medium 3 as described above, but is basically made of the same material as the photoconductive layer support 5 and has the same light transmittance. May be required. Specifically, when the charge holding medium 3 takes the shape of a flexible film, tape, or disk, a flexible plastic film is used, and when strength is required, a rigid sheet, glass, or the like is used. An inorganic material or the like is used.

The charge storage medium electrode 13 may be basically the same as the photoreceptor electrode 7, and is formed on the insulating layer support 15 by the same forming method as the photoreceptor electrode 7 described above.

Since the insulating layer 11 records information on the surface or inside thereof as a distribution of static charges, high insulating properties are required to suppress the movement of charges, and the specific resistance is 10 ¹⁴ Ω ·
It is required to have insulation properties of not less than cm. Such an insulating layer 11 can be formed by dissolving a resin or rubber in a solvent and coating or dipping, or by vapor deposition or sputtering.

Here, examples of the above resin and rubber include polyethylene, polypropylene, vinyl resin, styrene resin, acrylic resin, nylon 66, nylon 6, polycarbonate, acetal homopolymer, fluorine resin, cellulose resin, phenol resin, urea resin, and polyester resin. ,
Epoxy resin, flexible epoxy resin, melamine resin, silicone resin, phenoxy resin, aromatic polyimide, PP
O, polysulfone, etc., polyisoprene, polybutadiene, polychloroprene, isobutylene, extra high nitrile,
Rubber alone such as polyacryl rubber, chlorosulfonated polyethylene, ethylene / propylene rubber, fluorine rubber, silicon rubber, polysulfide synthetic rubber, urethane rubber,
Alternatively, a mixture is used.

Further, a layer is formed by attaching a silicon film, a polyester film, a polyimide film, a fluorine-containing film, a polyethylene film, a polypropylene film, a polyparabanic acid film, a polycarbonate film, a polyamide film or the like to the charge holding medium electrode 13 via an adhesive or the like. Even if the layer is formed by coating or dipping a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, a curing agent necessary for a rubber or the like, a solvent, etc. Good.

Further, as the insulating layer 11, a monomolecular film formed by a Langmuir-Blodget method or a monomolecular cumulative film can also be used.

In addition, a charge retention enhancing layer can be provided between the insulating layer 11 and the electrode surface or on the insulating layer 11. The charge retention enhancing layer refers to a layer into which electric charge is injected when a strong electric field (10 ⁴ V / cm or more) is applied, but which is not injected at a low electric field (10 ⁴ V / cm or less). As the charge retention enhancing layer, for example, SiO ₂ , Al ₂ O ₃ , SiC, SiN or the like can be used, and as the organic substance, for example, a polyethylene deposited film or a polyparaxylene deposited film can be used.

In order to more stably hold the electrostatic charge, the insulating layer 11
In addition, a substance having an electron-donating property (donor material) or a substance having an electron-accepting property (acceptor material) may be added. Donor materials include styrene, pyrene,
There are naphthalene-based, anthracene-based, pyridine-based, and azine-based compounds. Specifically, tetrathiofulvalene (TT
F), polyvinyl pyridine, polyvinyl naphthalene, polyvinyl anthracene, polyazine, polyvinyl pyrene, polystyrene and the like are used, and one kind or a mixture is used. As the acceptor material, there are a halogen compound, a cyan compound, a nitro compound and the like, and specifically, tetracyanoquinodimethane (TCNQ) trinitrofluorenone (TNF) and the like are used, and one kind or a mixture is used. The donor material and the acceptor material are used by adding about 0.001 to 10% to the resin or the like.

Further, in order to stably hold the charge, elemental element fine particles can be added to the charge holding medium. Elemental elements include the following elements in the periodic table: Group IA (alkali metal), Group IB (copper group), Group IIA (alkaline earth metal), Group IIB (zinc group), Group IIIA (aluminum group) ), IIIB (rare earth), IVB (titanium), VB (vanadium), VIB (chromium), VIB (manganese), VIII (iron) Group, platinum group) or IV group A (carbon group) as silicon, germanium, tin, lead, V
Antimony, bismuth, and VIA
As the group (oxygen group), sulfur, selenium, and tellurium are used in the form of fine powder. Metals among the above elemental elements can be used in the form of metal ions, fine powdery alloys, organic metals, and complexes. Further, the above element simple substance can be used in the form of an oxide, a phosphate, a sulfate, or a halide. These additives may be added to the charge holding medium such as the above-mentioned resins and rubbers in a very small amount, and may be added in an amount of about 0.01 to 10% by weight based on the charge holding medium. The insulating layer 11 is at least 1000 mm (0.1 μm) from the point of view of the insulating layer.
m) or more, and the thickness is preferably 100 μm or less from the viewpoint of flexibility.

The insulating layer 11 thus formed can be provided with a protective film on its surface in order to prevent damage or discharge of information charges on its surface. As the protective film, a rubber such as silicone rubber having adhesiveness, a resin such as polyterpene resin is formed into a film, and the film is adhered to the surface of the insulating layer 11, or a plastic film is formed using an adhesive such as silicone oil. It is good if the specific resistance is 10 ¹⁴ Ωcm or more, the film thickness is about 0.5 to 30 μm,
When the information of the insulating layer 11 needs to have high resolution, the thinner the protective film, the better. This protective layer may reproduce information from above the protective film at the time of reproducing information, or may reproduce the information of the insulating layer by peeling off the protective film.

As an electrostatic charge holding method, there is an electret that causes distribution and polarization of charges inside an insulating medium, other than the so-called free charge holding method of accumulating surface charges as described above.

FIG. 2 is a diagram showing a method for holding electrostatic charges using an optical electret, and the same numbers as those in FIG. 1 indicate the same contents.
In the figure, reference numeral 19 denotes a transparent electrode.

As shown in FIG. 2 (a), an electrode 13 is formed on a support 15 such as a film, and ZnS, CdS, and ZnO are formed on the electrode plate in a thickness of 1 to 5 μm by vapor deposition sputtering, CVD, coating method, or the like. I do. Then, when a transparent electrode 19 is superposed on the surface of the photosensitive layer in a contact or non-contact manner, and exposed under a voltage applied state (FIG. 2 (b)), charges are generated by light in the exposed portion and polarized by an electric field. Is trapped at that position (FIG. 2 (c)). Thus, an electret corresponding to the exposure amount is obtained. In the case of the charge holding medium shown in FIG. 2, there is an advantage that a separate photoconductor is not required.

FIG. 3 is a view showing an electrostatic holding method using a thermal electret, and the same reference numerals as those in FIG. 1 denote the same contents.

Examples of the heat electret material include polyvinylidene fluoride (PVDF), poly (VDF / ethylene trifluoride), poly (VDF / ethylene tetrafluoride), polyvinyl fluoride, polyvinylidene chloride, polyacrylonitrile, and poly-α-. The electrode substrate 13 is made of chloroacrylonitrile, poly (acrylonitrile / vinyl chloride), polyamide 11, polyamide 3, poly-m-phenylene isophthalamide, polycarbonate, poly (vinylidene cyanide vinyl acetate), PVDF / PZT composite, etc. A single layer of 1 to 50 μm is provided thereon, or two or more layers are laminated.

Then, before exposure, the medium is heated above the glass transition of the medium material by resistance heating or the like, and voltage application exposure is performed in that state (FIG. 3 (b)). At high temperatures, the mobility of ions is large, and in the exposed area, a high electric field is applied to the insulating layer,
Of the thermally activated ions, the negative charge collects on the positive electrode and the positive charge collects on the negative electrode to form a space charge, causing polarization. Thereafter, when the medium is cooled, the generated charges are trapped at the position even after the electric field is removed, and an electret corresponding to the exposure amount is generated (FIG. 3 (c)).

Next, as a method of inputting information to the insulating layer 11, there is a method using a high-resolution electrostatic camera or a recording method using a laser. First, the high-resolution electrostatic camera used in the present invention comprises a photoconductor 1 comprising a photoconductive layer 9 provided with a photoconductor electrode 7 on the front, instead of a photographic film used in a normal camera, A recording member is constituted by a charge holding medium comprising an insulating layer 11 having a charge holding medium electrode 13 provided on the rear surface thereof, and a voltage is applied to both electrodes so that the photoconductive layer becomes conductive according to incident light. An electrostatic latent image of an incident optical image is formed on a charge storage medium by accumulating electric charges on an insulating layer in accordance with the amount of incident light, and a mechanical shutter can be used. It can be used, and the electrostatic latent image can be held for a long period of time irrespective of a bright place or a dark place. In addition, a color filter that separates optical information into R, G, and B light components by a prism and takes out as parallel light is used, and one frame is formed with three sets of R, G, and B charge-retaining media, or By arranging the R, G, and B images on a plane to form one frame in one set, color photography can also be performed.

As a recording method using a laser, an argon laser (514.488 nm), a helium-neon laser (633 nm), a semiconductor laser (780 nm, 810 nm, etc.) are used as a light source.
A voltage is applied by bringing the photoreceptor and the charge holding medium into a planar shape and bringing the surfaces into close contact or facing each other at a certain interval. In this case, the photoconductor electrode may be set to the same polarity as the carrier of the photoconductor. In this state, laser exposure corresponding to the image signal, character signal, code signal, and line drawing signal is performed by scanning. Analog recording such as images is performed by modulating the laser light intensity, and digital recording such as characters, codes, and line drawings is performed by ON-OFF control of laser light. In the case where halftone dots are formed in an image, the halftone dots are formed by applying dot generator ON / OFF control to laser light.
Note that the spectral characteristics of the photoconductive layer in the photoreceptor need not be panchromatic, but may be any as long as they have sensitivity to the wavelength of the laser light source.

FIG. 4 is a diagram showing an embodiment of the latent image erasing method of the present invention.

As shown in FIG. 4 (a), when a predetermined voltage is applied between the photoreceptor 1 and the charge holding medium 3 by the power supply 17 and exposure is performed in this state, the insulating layer 11 of the charge holding medium 3 is exposed. , A negative charge is trapped and held, and a latent image is formed. To erase this latent image, as shown in FIG. 4 (b), when the polarity of the power supply 17 is reversed and the exposure is performed with the same exposure pattern as in FIG. The electric charge of the opposite polarity to that of FIG. 4 (a) is recorded on the upper part, so that the latent image formed by the exposure according to FIG. 4 (a) is cancelled, and the potential on the insulating layer 11 becomes 0 and the latent image becomes zero. The image is erased.

Further, as shown in FIG. 4 (c), if a voltage having the same polarity as that at the time of exposure in FIG. 4 (a) is applied and exposure is performed in a pattern opposite to that of FIG. Negative charges are uniformly charged and recorded on 11, and the latent image is erased. In the case of FIG. 4 (c), since the insulating layer 11 is maintained at a predetermined constant potential, if the exposure is performed with the polarity of the power supply voltage reversed, re-recording becomes possible.

FIG. 5 is a view showing another embodiment of the present invention, in which the latent image is erased by performing uniform exposure on the charge holding medium on which the latent image is formed.

FIG. 5 (a) is a diagram showing an example in which uniform exposure is performed by applying a voltage having the same polarity as that at the time of voltage application exposure. Since a portion where a latent image is formed is further charged by exposure, exposure is performed. When the exposure is continued, the charge is quickly saturated. Further, by continuing the exposure in a portion where the latent image is not formed, the charge amount on the portion is saturated. By performing the exposure for a certain time in this manner, the surface of the insulating image 11 reaches the saturation voltage, and the latent image is erased. In this state, rewriting can be performed by performing exposure with the power supply voltage having the opposite polarity.

FIG. 5 (b) shows an example in which uniform exposure is performed with an applied voltage having a polarity opposite to that at the time of exposure in FIG. 4 (a). In this case, the portions not exposed in FIG. The portion is saturated by charging, and then the portion where the latent image is formed by exposure is saturated to be uniformly charged over the entire surface, and the latent image is erased.
Also in this case, rewriting can be performed by setting the voltage to the opposite polarity.

FIG. 6 is a view showing an embodiment in which a latent image is erased by performing uniform charging by corona discharge.

In the present embodiment, for example, AC corona discharge is performed, and the insulating layer 11
The upper portion is uniformly charged with a positive or negative charge to erase the latent image. Of course, it is also possible to use a DC discharge instead of an AC discharge.

Next, a latent image erasing method by heating will be described with reference to FIGS.

FIG. 7 is a view showing a method of erasing a latent image by infrared heating, in which the insulating layer 11 is heated by irradiating the charge holding medium on which the latent image is formed with infrared light, and as a result, the conductivity of the insulating layer 11 increases. Then, the charge forming the latent image leaks and the latent image is erased.

FIG. 8 is a diagram showing an embodiment in which the latent image is erased by heating the resistance of the electrode of the charge holding medium by applying a current. The electrode of the charge holding medium is formed of a material having a resistance of 10 ⁶ Ωcm or less, and has a predetermined resistance, so that when electricity is supplied, heat is generated, and the charge holding medium itself is extremely thin and has a small heat capacity. Thus, the latent image is heated in a short time, the charge for forming the latent image leaks, and the latent image is erased.

FIG. 9 is a diagram showing the elimination of a latent image by microwave heating.
Due to the dielectric loss of the insulating layer 11, the insulating layer itself generates heat and rises in temperature, the conductivity increases, charges leak, and the latent image is erased.

FIG. 10 is a diagram showing an example of erasing a latent image by heating the surface of the insulating layer 11 of the charge holding medium using a thermal head.The thermal head 22 is heated, and the insulating layer 11 is heated in a contact or non-contact manner. Then, the charge forming the latent image is leaked to erase the latent image.

FIG. 11 is a view showing an embodiment in which a latent image is erased by irradiating ultraviolet rays.

FIG. 11 (a) shows an example in which ultraviolet light having the same pattern as the exposure pattern on which the latent image is formed is irradiated, and irradiation of ultraviolet rays generates carriers of electrons and holes in the insulating layer 11 to form a latent image. Since an electric field is generated in the portion where the latent image is formed, carriers having the opposite polarity to the charges are attracted and neutralized, and the charges having the opposite polarity flow to the ground side. As a result, the charges forming the latent image are neutralized and the latent image is erased.

FIG. 11 (b) shows an example in which the ultraviolet rays are uniformly irradiated on the surface of the charge holding medium, and the portion where the latent image is formed is neutralized as in FIG. Since no electric field is generated, the generated carriers are immediately recombined and disappear, so that no charge is accumulated on the insulating layer 11 as a whole and the latent image can be erased.

FIG. 12 is a view showing an embodiment in which the electric charge on the insulating layer 11 is leaked by the current collecting member. In the figure, reference numeral 31 denotes a conductive member, which has a brush 32. By scanning the surface of the charge holding medium with the brush 32, a charge is leaked and a latent image can be erased.

FIG. 13 is a diagram showing an example in which water vapor is sprayed onto a charge holding medium to impart conductivity, thereby leaking charges. Electric charges leak through this conductive gas, and a latent image can be erased.

〔The invention's effect〕

As described above, according to the present invention, a latent image on a charge holding medium having high insulation properties and which is difficult to erase can be erased very easily and reliably, so that the charge holding medium can be reused repeatedly. Becomes

[Brief description of the drawings]

FIG. 1 is a view for explaining a recording method in the electrostatic image recording / reproducing method of the present invention, FIG. 2 is a view showing an electrostatic charge holding method using an optical electret, and FIG. 3 is a view using a thermal electret. FIG. 4 is a view showing an electrostatic charge holding method, FIG. 4 is a view showing an embodiment of a latent image erasing method of the present invention, FIG. 5 is a view showing another embodiment of erasing a latent image by uniform exposure of the present invention, FIG. 6 is a view showing an embodiment in which a latent image is erased by performing uniform charging by corona discharge, FIG. 7 is a view showing a method of erasing a latent image by infrared heating, and FIG. FIG. 9 is a diagram showing an embodiment in which a latent image is erased by resistance heating by applying a current, FIG.
The figure shows a latent image erased by microwave heating, FIG. 10 shows an embodiment of erasing a latent image using a thermal head, and FIG. 11 shows an embodiment of erasing a latent image by irradiating ultraviolet rays. FIG. 12 is a diagram showing an embodiment in which electric charges are leaked by a current collecting member to erase a latent image, and FIG. 13 is a diagram showing an embodiment in which steam is blown to erase a latent image. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 3 ... Charge holding medium, 5 ... Photoconductive layer support, 7 ... Photoconductor electrode, 9 ... Photoconductive layer, 11 ... Insulating layer, 13 ... Charge holding medium electrode, 15 ... insulating layer support, 17
……Power supply.

Continuation of the front page (56) References JP-A-55-130543 (JP, A) JP-A-60-115960 (JP, A) JP-A-1-155375 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G03G 13/04-13/05 G03G 15/04-15/05 G03G 21/06-21/08 H04N 5/76 H04N 5/80-5/907

Claims (1)

(57) [Claims] A high-resolution electrostatic device comprising: a photoreceptor; a charge holding medium disposed opposite to the photoreceptor; means for applying a voltage between the photoreceptor and the charge holding medium; and means for exposing through the photoreceptor. A camera, on the charge holding medium on which the electrostatic latent image has been formed by the voltage application exposure, performing voltage application exposure with the same polarity as the latent image formation, and with the opposite exposure pattern, so that the charge holding medium is uniformly charged. A high-resolution electrostatic camera characterized in that a latent image on a charge holding medium is erased by forming charges.