JPH0277780A - Latent image erasing method for charge holding medium - Google Patents

Abstract

PURPOSE:To easily and securely erase a latent image on the charge holding medium and to use the medium repeatedly by performing exposure by reverse voltage application. CONSTITUTION:A specific voltage is applied between a photosensitive body 1 and the charge holding medium from a power source 17 to perform the exposure. Consequently, minus charges are trapped and held on the insulating layer 1 of the medium 3. Then the polarity of the power source 17 is inverted and exposure is carried out with a specific exposure pattern to record charges with the opposite polarity on the insulating layer 11. Consequently, the latent image formed by the exposure is canceled and the potential on the insulating layer 11 becomes zero, so that the latent image is erased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for erasing a latent image on a charge-retaining medium that is disposed facing a photoreceptor and forms and records an electrostatic latent image by applying a voltage and exposing it to light. .

[Prior Art] The applicant has already developed high-quality, high-resolution technology for silver halide photography, electrophotography, television photography, television photography using solid-state image sensors (CCD), etc. C. The processing process is simple and long-term storage is possible, and the stored characters, line drawings, images, and luminous intensity (1, O) information can be stored in 1iji according to the purpose.
We are proposing recording and reproducing using a charge-holding medium that can be reproduced arbitrarily and repeatedly with high quality (patent application 1986-
No. 121592).

[Problem to be solved by the invention]

By the way, although such a charge retention medium is capable of recording an electrostatic latent image for a long time, it is not easy to erase the latent image because of its high insulating properties. Furthermore, unless this latent image can be easily erased, the advantage of repeatedly using it for recording and reproduction cannot be taken advantage of.

The present invention is intended to solve the above-mentioned problems, and provides a method for erasing latent images on a charge-retaining medium that easily and reliably erases latent images on a charge-retaining medium and enables repeated use of the charge-retaining medium. Aim for Goshichi.

[Means to solve the problem]

The present invention provides a method for erasing a latent image on a charge-retaining medium, which is disposed facing a photoreceptor and has an electrostatic latent image formed thereon by voltage application exposure, and includes reverse voltage application exposure, uniform exposure, corona charging, heating,
Uniform irradiation means that the latent image is erased by means such as ultraviolet irradiation, surface scanning of a conductive member, and steam blowing.

[Function] The present invention provides a method for erasing a charge-retaining medium that is disposed opposite to a photoreceptor and has an electrostatic latent image recorded thereon by applying a voltage and exposing the charge-retaining medium. Uniform exposure by applying a voltage, exposure in a pattern opposite to that used during recording, leakage of charge due to heating of the charge holding medium, erasure of patterns due to charges generated by ultraviolet irradiation, removal of charges by spraying with a current collecting member or conductive vapor, etc. The latent image on the charge holding medium is erased using leakage, and the latent image can be easily and reliably erased and reused.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 shows the electrostatic image recording and reproducing method of the present invention. 1
This is a diagram for explaining the force method. In the diagram, 1 is a photoconductor, 3 is a charge holding medium, 5 is a photoconductive layer support, 7 is a photoconductor electrode, and 9
is a photoconductive layer, 11 is an insulating layer, 13 is a charge retention medium electrode,
15 is an insulating layer support, and 17 is a power source.

In FIG. 1, exposure is performed from the photoreceptor 1 side, and first a photoconductive layer support 5 made of glass with a thickness of 1 mm is exposed.
Above is a transparent photoreceptor electrode 7 made of IT○ with a thickness of 1000
A photoconductive layer 9 having a thickness of about 10 μm is formed on this layer to form a photoreceptor 1. A charge holding medium 3 is placed with respect to the photoreceptor 1 with a gap of about 10 μm in between. The charge retention medium 3 is formed by depositing a layer of 1000 mm thick on an insulating layer support 15 made of glass with a thickness of 1! The electrode I3 is formed by vapor deposition, and the insulating layer 11 with a thickness of 10 μm is formed on the electrode 13'.

First, as shown in FIG. 1(A), 1
The charge retention medium 3 is set through a gap of about 0 μm,
As shown in FIG. 1 (b), the electrodes 7.13 are
A voltage is applied between them. In a dark place, since the photoconductive layer 9 is a high-resistance material, no change occurs between the electrodes. When light is incident from the photoreceptor 1 side, the photoconductive layer 9 at the portion where the light is incident exhibits conductivity, a discharge occurs between the photoconductive layer 9 and the insulating layer 11, and charges are accumulated in the insulating layer 11.

When the exposure is finished and 7 seconds have passed, Figure 1 (ha)! The formation of the electrostatic latent image is completed by turning off the voltage as shown, and then taking out the charge holding medium 3 as shown in FIG. 1(d).

Note that the photoreceptor 1 and the charge holding medium 3 may be in contact rather than in non-contact as described in -1-. In the case of contact, the photoreceptor 1 and the charge holding medium 3 may be connected directly from the photoreceptor electrode 7 side to the exposed portion of the photoconductive layer 9. Alternatively, a negative charge is injected, this charge is attracted to the electrode 13 of the three charge holding media, passes through the photoconductive layer 9, and when it reaches the surface of the insulating layer 11, the charge movement stops and is injected into that part. Charge is accumulated. Then, when the photoreceptor 1 and the charge retention medium 3 are separated,
The insulating layer 11 is separated while still storing charge.

This recording method is used for planar analog recording.
The surface charge on the formed insulating layer]1 is exposed to the air environment, but since air has good insulating properties, it can be used in both bright and dark places. Regardless, it will be stored for a long time without discharging.

The charge storage period on the insulating layer 11 is determined by the properties of the insulator, and is affected by the charge trapping properties of the insulator in addition to the insulating properties of air. In the above explanation, charge is explained as a surface charge, but injected charge may simply accumulate on the surface, or it may microscopically penetrate into the interior near the surface of an insulator, creating electrons or In some cases, holes may be trapped, resulting in long-term storage. Further, the surface of the insulating layer 11 may be covered with an insulating film or the like for storage in order to prevent physical damage to the charge holding medium and discharge when the humidity is high.

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

The material and thickness of the photoconductive layer support 5 are not particularly limited as long as they have a certain level of strength to support the photoreceptor, such as flexible plastic film, metal foil, and paper. , or glass, plastic sheet,
A rigid body such as metal +Fj (which can also serve as an electrode) is used. However, if it is used in a device that records information by entering light from the photoconductor side, it will naturally need to have the property of transmitting that light. For example, if it is used in a camera that uses natural light as incident light and enters from the photoconductor side. A transparent glass plate or a plastic film or sheet with a thickness of about 1 mm is used for this purpose.

The photoreceptor electrode 7 is formed on the photoconductive layer support 5 except when metal is used for the photoconductive layer support 5, and the material thereof is limited as long as the specific resistance value is 10 6 Ω·cm or less. Rather, they are inorganic metal conductive films, inorganic metal oxide conductive films, etc. Such a photoreceptor electrode 7 is placed on the photoconductive layer support 5,
It is formed by vapor deposition, sputtering, CVD, coating, plating, dipping, electrolytic polymerization, etc. Further, the thickness needs to be changed depending on the electrical properties of the material constituting the photoreceptor electrode 7 and the applied voltage when recording information.
Approximately 0 people. The photoreceptor electrode 7 and the photoconductive layer support 5
Similarly, if it is necessary to input information light,
The optical properties described in 1 are required, for example, when information light is visible light (
400 to 700 nm), I To (InzO
3-3n02), sputtering S n 02, etc.
Transparent electrodes coated by vapor deposition or by making ink with their fine powders together with a binder, Au, A
A translucent electrode made by vapor deposition or sputtering of I, Ag, Ni, Cr, etc., tetracyanoquinodimethane (T
CNQ), an organic transparent electrode coated with polyacetylene, etc. is used.

The above electrode materials can also be used when the information light is infrared light (700 nm or more), but in some cases, colored visible light absorbing electrodes can also be used to cut visible light.

Furthermore, when the information light is ultraviolet light (400 Ωm or less), the above electrode materials can basically be used, but electrode substrate materials that absorb ultraviolet light (organic polymer materials, soda glass, etc.) are not preferable. A material that transmits ultraviolet light, such as quartz glass, is preferred.

The photoconductive layer 9 is a conductive layer in which photocarriers (electrons, holes) are generated in the irradiated area when irradiated with light, and these carriers can move across the layer width, especially when an electric field is present. This is the layer where the effect is noticeable in some cases. The materials include inorganic photoconductive materials, organic photoconductive materials, organic-inorganic composite photoconductive materials, and the like.

Below, these photoconductive materials and methods of forming the photoconductive layer will be explained.

(A) Inorganic photoreceptor (photoconductor) Inorganic photoreceptor materials include amorphous silicon, amorphous selenium, cadmium sulfide, zinc oxide, and the like.

(a) Amorphous silicon photoreceptor As an amorphous silicon photoreceptor, ■Hydrogenated amorphous silicon (a-3i:) I) ■Fluorinated amorphous silicon (a-3t:F)・These are not doped with impurities・B ,, AI, Ga, In, Tf, etc. are made into P type (hole transport type) by doping, P,, Ag,, S
There is one in which B, B, etc. are made into N type (electron transport type) by doping.

The method for forming the photoreceptor layer is to introduce silane gas and impurity gas together with hydrogen gas into a low vacuum.
I Torr), the film can be formed by depositing it on an electrode substrate heated or not heated by glow discharge, it can be formed by a thermochemical reaction on a heated electrode substrate, or it can be formed by vapor deposition or sputtering of a solid raw material. It can be used as a single layer or in a laminated form. The film thickness is 1 to 50 μm.

Further, in order to prevent charge from being injected from the transparent electrode 7 and charging as if it were exposed to light even though it was not exposed, a charge injection prevention layer can be provided on the surface of the photoreceptor electrode 7. As this charge injection prevention layer, a-5iN layer, a-5iN layer, a-5i
It is preferable to provide an insulating layer such as a C layer, a 5iOz layer, an Affi layer, an O layer, or the like. If this insulating layer is made too thick, no current will flow when exposed to light, so it needs to be at least 1000 Å or less, and considering ease of fabrication, it should be 400 to 50 Å.
A culm density of 0 is desirable.

In addition, as a charge injection prevention layer, it is preferable to provide a charge transport layer on the electrode substrate element that has a charge transport ability of opposite polarity to the polarity of the electrode substrate by utilizing a rectifying effect.If the electrode is negative, a hole transport layer, an electrode If is positive, an electron transport layer is provided. For example, a-3i in which Si is doped with boron:
I(n) improves the hole transport properties, provides a rectifying effect, and functions as a charge injection prevention layer.

(b) Amorphous selenium photoreceptor The amorphous selenium photoreceptor includes: ■Amorphous selenium (a-5e) ■Amorphous selenium tellurium (a-5e-Fe) ■Amorphous arsenic selenium compound (a-ASzSe+)■
There is an amorphous arsenic selenium compound +Te.

This photoreceptor was fabricated by thin evaporation and sputtering, and a charge injection layer of SiOZ, 8(!20+,
A 5iC1SiN layer is provided on the electrode substrate by vapor deposition, sputtering, glow discharge method, or the like. In addition, a laminated type photoreceptor may be produced by combining and (1) to (2). The thickness of the photoreceptor layer is similar to that of an amorphous silicon photoreceptor.

(c) Cadmium sulfide (CdS) This photoreceptor is manufactured by coating, vapor deposition, and sputtering methods. In the case of vapor deposition, solid particles of CdS are placed on a tungsten board and vapor deposited by resistance heating, or by E
This is done by B (electron beam) evaporation. In the case of sputtering, a CdS target is used to deposit on the substrate in argon plasma. In this case, CdS is usually deposited in an amorphous state, but a crystalline oriented film (oriented in the film thickness direction) can also be obtained by selecting sputtering conditions. For coating, C
It is preferable to disperse dS particles (particle size 1 to 100 μm) in a binder, add a solvent, and coat on the substrate. .

(d) Zinc oxide (Zn 2 O) This photoreceptor is produced by a coating method or a CVD method. As a coating method, ZnS particles (particle size 1~
100 μm) in a binder, add a solvent, and coat on a substrate. Also CVD
The method involves mixing organic metals such as diethylzinc and dimethylzinc with oxygen gas in a low vacuum (10-2 to ITorr), and causing a chemical reaction on a heated electrode substrate (150 to 400°C) to form zinc oxide. Deposit as a film. In this case as well, a film oriented in the film thickness direction can be obtained.

(B) Organic photoreceptor Organic photoreceptors include single-layer photoreceptors and functionally separated photoreceptors.

(a) Single-layer photoreceptor A single-layer photoreceptor is made of a mixture of a charge-generating material and a charge-transporting material.

<Charge-generating substances> Substances that easily generate charges by absorbing light, such as ab-based pigments, disazo-based pigments, trisazo-based pigments, phthalocyanine-based pigments, perishin-based pigments, pyrylium dyes,
Cyanine dyes and methine dyes are used.

Charge transport material system> A material with good transport properties for ionized charges, such as hydrazone-based, pyrazoline-based, polyvinylcarbazole-based,
There are carbazole-based, stilbene-based, anthracene-based, naphthalene-based, I-ridiphenylmethane-based, azine-based, amine-based, aromatic amine-based, etc.

Alternatively, a charge-transfer complex may be formed by forming a complex with a charge-generating substance and a charge-transporting substance.

Normally, photoreceptors have photosensitive properties determined by the light absorption properties of the charge generating substance, but when a charge generating substance and a charge transporting substance are mixed to form a complex, the light absorption properties change. It is only felt in the ultraviolet region, and trinitrofluoro/y (TNF) is not felt around the wavelength of 400 nm, but P V K T NF 89
The body becomes sensitive to wavelengths up to 650 nm.

The thickness of such a single-layer photoreceptor is preferably 10 to 5 μm.

(b) Functionally separated photoreceptor Charge generating materials easily absorb light but have the property of trapping light, while charge transporting materials have good charge transport properties but poor light absorption properties. Therefore, it is a type in which a charge generation layer and a charge transport layer are laminated in order to separate the two and fully exhibit their respective characteristics.

(Charge generation layer) Examples of substances forming the charge generation layer include azo, disazo, trisazo, phthalocyanine, acidic xanthene dye, cyanine, styryl dye, pyrylium dye, perylene, methine, a-3e,,a-3
t, azulenium salt type, squalium base yarn, etc.

Charge Transport Layer> Examples of substances forming the charge transport layer include hydrazone, birapurin, PVK, carbazole, oxazole, triazole, aromatic amine, amine, triphenylmethane, and polycyclic aromatics. There are group compounds, etc.

The method for manufacturing a functionally separated photoreceptor is to first dissolve a charge generating substance in a solvent and apply it to the electrode, then dissolve the charge transport layer in a solvent and apply it to the charge transport layer, and then remove the charge generating layer from zero.
．． The thickness of the charge transport layer is preferably 1 to 10 μm, and the thickness of the charge transport layer is 10 to 50 μm.

In addition, in the case of either a single-layer photoconductor or a functionally separated photoconductor, silicone resin, styrene-butadiene copolymer resin, epoxy resin, acrylic resin, saturated or unsaturated polyester resin, polycarbonate resin, polyvinyl is used as a binder. Add 0.1 to 10 parts of acetal Hli, phenol resin, polymethyl methacrylate (PMMA) resin, melamine resin, polyimide resin, etc. to each part of the charge generation material and charge generation material to make it easier to adhere. . As the coating method, a dipping method, a vapor deposition method, a sputtering method, etc. can be used.

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

The charge injection prevention layer prevents dark current (
This can be provided to prevent charge injection from the electrode), that is, a phenomenon in which charges move in the photosensitive layer as if it had been exposed even though it had not been exposed.

There are two types of charge injection prevention layers: a layer that utilizes a so-called tunneling effect and a layer that utilizes a rectification effect. First, in a device that utilizes the so-called tunneling effect, when only a voltage is applied, current does not flow to the photoconductive layer or the surface of the insulating layer due to this charge injection prevention layer, but when light is incident, the current does not flow to the surface of the photoconductive layer or the insulating layer. Since one of the charges (electrons or holes) generated in the photoconductive layer is present in the charge injection prevention layer, a high electric field is applied, causing a tunnel effect and current flowing through the charge injection prevention layer. . Such a charge injection prevention layer is formed of a single layer such as an inorganic insulating film, an organic insulating polymer film, an insulating monomolecular film, or a stack of these. Examples of the inorganic insulating film include As2O3, B2O3, etc. , RizOz , CdS , C
aO,, Ce0z, Cr2O3, Coo, Ge0z,
]9 HfO,, Fe2O3, La2's, MgO, Mn
O2, Nd2O,, Nb2O! ,PbO,,5bz
03. 5t02, Sea□, Taz05, TiO
2, ho3, V2O,, Y2O5, Y2O3, Zr
O□, BaTiO3, 81203, BaTiO3, Ca
O-3rO, Ca0-Y2O3, Cr-3iO11,1
Ta03, PbTi0a, PbZr0. , Zr02-C
o,,Zr(12-5ing,AIN,B
N,,NbN,,5is)L4,TaN
iN,,VN,ZrN.

It is formed of SiC, TiC, WC, Al4C3, etc. by glow discharge, vapor deposition, sputtering, or the like. The thickness of this layer is determined depending on the material used, taking into account the insulating properties to prevent charge injection and the tunnel effect. Next, the charge injection prevention layer utilizing a rectifying effect is provided with a charge transporting layer having a charge transporting ability of opposite polarity to the polarity of the electrode substrate using a rectifying effect. That is, such a charge injection prevention layer is formed of an inorganic photoconductive layer, an organic photoconductive layer, and an organic-inorganic composite photoconductive layer, and has a thickness of about 0.1 to 10 μm. Specifically, when the electrode is negative, B, , A1 . ,
Amorphous silicon photoconductive layer doped with Ga, In, etc., amorphous selenium, or oxadiazole, birapurin, polyvinylcarbazole, stilthen, anthracene, naphthalene, tridiphenylmethane, triphenylmethane, azine, amine, aromatic amine, etc. in the resin. When the electrode is positive, an amorphous silicon photoconductive layer doped with P, N, AsXSb, Bi, etc., a ZnO photoconductive layer, etc. are formed by glow discharge, vapor deposition, sputtering, etc. It is formed by a method such as CVD or coating.

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

The charge retention medium 3 is used together with the photoreceptor 1 to record information as a distribution of electrostatic charges on the surface or inside of the insulating layer 11 constituting the charge retention medium 3.
The charge retention medium itself is used as a recording medium. Therefore, the shape of this charge retention medium can take various shapes depending on the information to be recorded or the recording method. For example, when used in an electrostatic camera, it takes the form of a general film (single frame or continuous frame) or a disk, and when recording digital or analog information using a laser, etc., it takes the form of a tape or a disk. , or a curved shape.

The insulating layer support 15 strongly supports the charge holding medium 3 as described above, and 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 retention medium 3 takes the form of a flexible film, tape, or disk, a flexible plastic film is used; when strength is required, a rigid sheet, glass, etc. is used. Inorganic materials etc. are used.

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

Since the insulating layer 11 records information as a distribution of static charges on its surface or inside, it needs to have high insulation properties to suppress the movement of charges, and has a specific resistance of 10'4.
It is required to have an insulation property of Ω·cm or less. Such an insulating layer 11 can be formed by dissolving resin or rubber in a solvent and coating or dipping it, or by vapor deposition or sputtering.

Here, examples of the resins and rubbers include polyethylene, polypropylene, vinyl resin, styrene resin, acrylic resin, nylon 66, nylon 6, polycarbonate, acetal homopolymer difluororesin, cellulose resin, and phenol resin.

Urea resin, polyester resin, epoxy resin, flexible epoxy resin, melamine resin, silicone resin, phenoxy resin, aromatic polyimide, PPO polysulfone, etc.
Also polyisoprene, polybutadiene, polychloroprene, isobutylene.

Extremely high nitrile 2 polyacrylic rubber, chlorosulfonated polyethylene, ethylene/propylene rubber.

Fluororubber, silicone rubber, polysulfide synthetic rubber.

A single rubber such as urethane rubber or a mixture thereof is used.

In addition, silicone film, polyester film, polyimide film, fluorine-containing film, polyethidine film, polypropylene film, polyparabanic acid film,
A layer may be formed by pasting polycarbonate I film, polyamide film, etc. on the charge holding medium electrode 13 via adhesive, or thermoplastic resin, thermosetting resin, ultraviolet curable resin, electron beam curing. The layer may be formed by adding necessary curing agents, solvents, etc. to a rubber or the like, and coating or dipping the mixture.

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

Further, a charge retention reinforcing layer can be provided between these insulating layers 11 and the electrode surface or on the insulating layer 11. The charge retention enhancement layer is a strong electric field (104V/cm or more)
is applied, charge is injected, but at a low electric field (10'
V/cm or less), this refers to a layer in which no charge is injected.

As the charge retention reinforcing layer, for example, 5i02, old zo, 3
, SiC, SiN, etc. can be used, and as the organic material, for example, a polyethylene vapor deposited film or a polyvaraxylene vapor deposited film can be used.

In addition, in order to hold static charge more stably, the insulating layer 11
It is preferable to add a substance having electron-donating properties (donor material) or a substance having electron-accepting properties (acceptor material) to the material. Donor materials include styrene, pyrene,
There are naphthalene-based, anthracene-based, pyridine-based, and azine-based compounds, specifically tetrathiofulvalene (TT
F), polyvinylpyridine, polyvinylnaphthalene, polyvinylanthracene, voriazine, polyvinyl vinyl
Polystyrene, polystyrene, etc. are used singly or as a mixture. In addition, acceptor materials include halogen compounds, cyanide compounds, nitro compounds, etc. Specifically, tetracyanoquinodimethane (TCNQ) and linitrofluorenone (TNF) are used, and they can be used singly or in combination. reactor. The donor material and acceptor material are
It is used by adding about 0.001 to 10% to resin etc.

Furthermore, in order to stably retain the charge, elementally suspended fine particles can be added to the charge retaining medium. Elements in group TA (alkali metals) of the periodic table and group IB (
Copper group), IIA group (alkaline earth metals), 17B group (zinc group), mA group (aluminum group), IB group (
Rare earths), Group B (titanium group), Group VB (vanadium group), VTB group (chromium group), Group Group B (manganese group), Group II (iron group, platinum group), and The IVA group (carbon group) includes silicon, germanium, tin, lead, and the VA group (carbon group).
The nitrogen group) includes antimony, bismuth, and the VIA group (nitrogen group).
Sulfur, selenium, and tellurium are used in fine powder form as oxygen group). Further, metals among the elements listed in item 1 can be used in the form of metal ions, fine powder alloys, organic metals, and complexes.

Furthermore, element L can be used in the form of an oxide, phosphorus oxide, sulfide, or halide. These additives need only be added in a very small amount to the charge retention medium such as the resin or rubber mentioned above, and the amount added is 0.0% relative to the charge retention medium.
It may be about 1 to 10% by weight. In addition, the insulating layer 11 needs to have a thickness of at least 2 mm (at most 1000 m (011 m) or more) from the viewpoint of insulation, and from the viewpoint of flexibility, it needs to have a thickness of 10 m
It is preferably 0 μm or less.

A protective film can be provided on the surface of the insulating layer 11 formed in this manner to prevent damage or discharge of information charges on the surface. The protective film may be formed into a film of sticky rubber such as silicone rubber or resin such as polyterpene resin and adhered to the surface of the insulating layer 11, or a plastic film may be used with an adhesive such as silicone oil. It is best to attach it with a specific resistance of 1014Ω.
It is sufficient as long as it is less than -1 cm, and the film thickness is 0.5 to 30 cm.
The thickness of the protective film is on the order of μm, and if the information on the insulating layer 11 needs to have high resolution, the thinner the protective film is, the better. This protective layer is
When reproducing information, the information can be reproduced from the protective film (,
Furthermore, the information on the insulating layer can be reproduced by peeling off the protective film.

In addition to the so-called free charge retention method that accumulates surface charges as described above, there are other methods for retaining static charge, such as the electret/node method that generates charge distribution and polarization inside the insulating medium. This figure shows the electrostatic charge holding method used, and the same numbers as in FIG. 1 indicate the same contents. In addition, in the figure, 19 is a transparent electrode.

As shown in FIG. 2(a), an electrode 13 is formed on a support 15 such as a film, and the electrode plate 1 is coated with ZnS.

One layer of CdS and ZnO is formed with a thickness of 1 to 5 Htm by vapor deposition, CVD, D-ting method, or the like. Then, a transparent electrode 19 is placed on the surface of this photosensitive layer in contact or non-contact,
When exposed with a voltage applied (Figure 2 (b)), charges are generated by the light in the exposed area, polarized by the electric field, and the charges are trapped at that position even if the electric field is removed (Figure 2 (b)). Ha)). In this way, an electret corresponding to the exposure amount is obtained. Note that the charge retention medium shown in FIG. 2 has the advantage of not requiring a separate photoreceptor.

5. FIG. 3 is a diagram showing a method of retaining an electrostatic charge using thermal ellets, and the same numbers as in FIG. 1 have the same contents.

Examples of thermal electret materials include polyvinylidene fluoride (PVDF), poly(VDF/fftri)soethylene), poly(VDF/tetrafluoroethylene), polyvinyl fluoride, and polyvinylidene chloride.

Polyacrylonitrile, poly-α-chloroacrylonitrile, poly(acrylonitrile/vinyl chloride), polyamide 11. Polyamide 3. Poly m-F-L nylene isophthalamide, polycarbonate 2 poly(vinylidene cyanide vinyl acetate).

Made of PVDF/PZT composite etc., which is used as an electrode substrate]
3 is provided with a layer of 1 to 50 μm, or two types of base layers are laminated.

Then, before exposure, the medium is heated to the glass transition group of the medium material described in 1. by resistance heating or the like, and in this state, voltage is applied and exposure is performed (FIG. 3 (b)). At high temperatures, the mobility of ions increases, and a high electric field is applied to the insulating layer in the exposed area, and among the thermally activated ions, negative charges are transferred to positive ones.
Positive charges gather at the negative electrode to form space charges, resulting in polarization. Thereafter, when the medium is cooled, the generated charges are trapped at that position even when the electric field is removed, producing electrets corresponding to the exposure amount (FIG. 3 (c)).

Next, methods for inputting information to the insulating layer 11 include a method using a high-resolution electrostatic camera and a recording method using a laser. First, the high-resolution electrostatic camera used in the present invention consists of a photoreceptor 1 consisting of a photoconductive layer 9 with a photoreceptor electrode 7 provided on the front surface, and a photoreceptor 1, instead of the photographic film used in ordinary cameras. 1 and a charge retention medium consisting of an insulating layer 11 with a charge retention medium electrode 13 provided on the rear surface, and a recording member is constituted by applying a voltage to the picture electrode to make the photoconductive layer conductive in accordance with incident light. This method forms an electrostatic latent image of an incident optical image on a charge storage medium by accumulating charges on an insulating layer according to the amount of incident light.A mechanical shutter can also be used, and an electric shutter can also be used. It is easy to use, and the electrostatic latent image can be retained for a long time regardless of whether it is in a bright or dark place. In addition, a prism separates the optical information into R, G, and B light components, and a color filter is used to extract them as parallel light, and one frame is formed with three sets of charge-holding media separated into R, G, and B, or one Color photography can also be performed by arranging R, G, and B images on a thousand planes, making one set one frame.

For recording methods using lasers, the light sources include argon laser (514,488 nm), helium-neon laser (633 nm), and semiconductor laser (780 nm).
(nm, 810 nm, etc.), and a voltage is applied to the photoreceptor and the charge holding medium with their surfaces brought into close contact with each other or facing each other at a fixed interval. In this case, it is preferable to set the photoreceptor electrode to the same polarity as the carrier of the photoreceptor.

In this state, laser exposure corresponding to image signals, character signals, coat signals, and line drawing signals is performed by scanning. Analog recording such as images is performed by modulating the light intensity of the laser, and digital travel such as characters, codes, and line drawings is performed by ON-OFF control of the laser light. Further, halftone dots in an image are formed by applying dot generator ON-OFF control to laser light. Note that the spectral characteristics of the photoconductive layer in the photoreceptor do not necessarily have to be panchromatic ink;
It only needs to be sensitive 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), a photoreceptor 1 and a charge holding medium 3
When a predetermined voltage is applied by the power supply 17 between the charge holding medium 3 and exposure is performed in this state, negative charges are trapped and held on the insulating layer 11 of the charge holding medium 3, and a latent image is formed. To erase this latent image, as shown in FIG. 4(b), the polarity of the power source 17 is reversed and the insulating layer 1 of the charge retention medium 3 is exposed using the same exposure pattern as shown in FIG. 4(a).
Charges of opposite polarity to those in FIG. 4(a) are recorded on the insulating layer 11, and therefore the latent image formed by the exposure in FIG. 4(a) is canceled, and the potential on the insulating layer 11 becomes O. The latent image is erased.

In addition, as shown in Figure 4 (C), if a voltage of the same polarity as in the exposure in Figure 4 (A) is applied and exposure is performed in the opposite pattern to that in Figure 4 (A), the insulating layer Each time a negative charge is uniformly recorded on the surface of the photosensitive drum 11, the latent image is erased. In the case of FIG. 4(c), since the insulating layer 11 is held at a predetermined constant potential, rerecording is possible by reversing the polarity of the power supply voltage and performing exposure.

FIG. 5 is a diagram showing another embodiment of the present invention, in which a charge holding medium on which a latent image is formed is uniformly exposed to light.
The latent image is erased.

Part 5 (a) is a diagram showing an example of uniform exposure by applying a voltage of the same polarity as during voltage application exposure. If the exposure continues, it will quickly become saturated, and if the exposure continues even in areas where no latent image has been formed, the amount of charge on those areas will become saturated. By performing exposure for a certain period of time, the surface of the insulating image 11 reaches a saturation voltage, and the latent image is erased. In this state, if the power supply voltage is reversed in polarity and exposure is performed, rewriting is possible.

Figure 5 (b) shows an example of uniform exposure using an applied voltage of opposite polarity to the exposure shown in figure 4 (a).
In step (a), the unexposed areas are first saturated with positive charge, and then the exposed areas on which the latent image is formed are saturated and become uniformly charged over the entire surface, erasing the latent image. In this case as well, rewriting can be performed by changing the voltage to the opposite polarity.

FIG. 6 is a diagram showing an embodiment in which latent images are erased by performing uniform charging by corona discharge.

In this embodiment, for example, AC corona discharge is performed, and the insulating layer 11
The latent image is erased by uniformly charging the upper surface with positive or negative charges. Of course, it is also possible to discharge by direct current instead of alternating current.

Next, a method of erasing a latent image by heating is shown in FIGS. 7 to 10.

FIG. 7 is a diagram showing a method of erasing a latent image by infrared heating, in which insulating layer 11 is heated by irradiating infrared rays to a charge holding medium on which a latent image has been formed, and as a result, the conductivity of insulating layer 11 is increased. The charge forming the latent image leaks and the latent image is erased.

FIG. 8 is a diagram showing an embodiment in which latent images are erased by resistive heating by applying current to electrodes of a charge holding medium.

The electrodes of the charge retention medium are made of a material that exhibits a resistance of 106 Ω・cm or less, and have a certain resistance, so they generate heat when electricity is applied to them, and the charge retention medium itself is extremely thin and has a small heat capacity, so it is short-lived. It is heated over time, and the charge that forms the latent image leaks out, erasing the latent image.

Figure 9 shows the erasure of a latent image by microwave heating.Due to dielectric loss in the insulating layer 11, the insulating layer itself generates heat and temperature rises, conductivity increases, charge leaks, and the latent image is erased. It will be done.

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 retention medium using a thermal head.
The thermal head 22 is heated to heat the insulating layer 11 with or without contact, thereby leaking the charge forming the latent image and erasing the latent image.

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

FIG. 11(a) shows an example in which ultraviolet light is irradiated in the same pattern as the exposure pattern on which the latent image is formed, and electron and hole carriers are generated in the insulating layer 11 by the ultraviolet irradiation.
In the area where the latent image is formed, an electric field is generated due to the charges forming the latent image, so carriers of the opposite polarity to the charges are attracted and neutralized, and the charges of 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.

Figure 1I (b) shows an example in which ultraviolet rays are uniformly irradiated onto the surface of a charge-retaining medium, where the charge is neutralized in the area where the latent image is formed, as in Figure 11 (a), and in other areas. Since no electric field is generated, the generated carriers immediately recombine 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 diagram showing an embodiment in which charges on the insulating layer 11 are leaked by a current collecting member. In the figure, 31 is a conductive member, which has a brush 32. By scanning the surface of the charge holding medium with the brush 32, the charge can be leaked and the 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 LJ conductivity to leak the charge, and the charge leaks through this conductive gas, making it possible to erase the latent image.

〔Effect of the invention〕

As described above, according to the present invention, a latent image on a charge-retaining medium that is highly insulating and difficult to erase can be erased extremely easily and reliably, so that the charge-retaining medium can be repeatedly reused. becomes.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the recording method in the electrostatic image recording and reproducing method of the present invention, FIG. 2 is a diagram showing an electrostatic charge holding method using a photoelectret, and FIG. 4 is a diagram showing an embodiment of the latent image erasing method of the present invention; FIG. 5 is a diagram showing another embodiment of the latent image erasing method by uniform exposure of the present invention; Figure 6 shows an example of erasing a latent image by uniformly charging it with corona discharge, Figure 7 shows a method of erasing a latent image by infrared heating, and Figure 8 shows how electricity is applied to the electrodes of the charge retention medium. FIG. 9 shows an embodiment in which latent images are erased by resistance heating.
The figure shows an example of erasing a latent image by microwave heating, Figure 10 shows an example of erasing a latent image using a thermal head, and Figure 11 shows an example of erasing a latent image by irradiating ultraviolet rays. FIG. 12 is a diagram showing an embodiment in which a latent image is erased by leaking charges by a current collecting member, and FIG. 13 is a diagram showing an embodiment in which a latent image is erased by spraying steam. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 3... Charge retention medium, 5... Photoconductive layer support, 7... Photoreceptor electrode, 9... Photoconductive layer,
11... Insulating layer, 13... Charge retention medium electrode, 15
... Insulating layer support, 17... Power supply. Applicant Dai Nippon Printing Co., Ltd. Agent Patent attorney Masanobu Hirukawa (4 others)
Castle Thief ■ 9 Castle

Claims (12)

[Claims] (1) A method for erasing a latent image of a charge-retaining medium, which is disposed facing a photoreceptor and has an electrostatic latent image formed thereon by voltage application exposure, the method comprising performing reverse voltage application exposure. Image deletion method. (2) The method for erasing a latent image on a charge retention medium according to claim 1, wherein the exposure pattern during exposure by applying a reverse voltage is the same as the exposure pattern during latent image formation. (3) The method of erasing a latent image on a charge retention medium according to claim 1, wherein the exposure pattern during exposure by applying a reverse voltage is a pattern opposite to the exposure pattern during latent image formation. (4) A method for erasing a latent image on a charge-retaining medium that is disposed opposite to a photoreceptor and has an electrostatic latent image formed by voltage application exposure, in which uniform exposure is performed by applying voltages of the same polarity or different polarity. A method for erasing a latent image on a charge retention medium, characterized by: (5) A method for erasing a latent image of a charge-retaining medium disposed facing a photoreceptor and having an electrostatic latent image formed thereon by voltage application exposure, the charge-retaining medium being uniformly charged by corona discharge. Latent image removal method. (6) A method for erasing a latent image of a charge-retaining medium, which is disposed facing a photoconductor and has an electrostatic latent image formed thereon by voltage application exposure, the method comprising heating the charge-retaining medium. Image deletion method. (7) A method for erasing a latent image of a charge-retaining medium disposed facing a photoconductor and having an electrostatic latent image formed thereon by voltage application exposure, the heating means including infrared heating, resistance heating, microwave heating,
7. The method of erasing a latent image on a charge holding medium according to claim 6, wherein heating is performed using a thermal head. (8) A method for erasing a latent image of a charge-retaining medium, which is disposed facing a photoconductor and has an electrostatic latent image formed thereon by voltage application exposure, the method comprising irradiating the charge-retaining medium with ultraviolet rays. How to remove latent images. (9) The method of erasing a latent image on a charge retention medium according to claim 8, wherein the ultraviolet rays have the same pattern as that during voltage application exposure. (10) The method for erasing a latent image on a charge retention medium according to claim 9, wherein the surface of the charge retention medium is uniformly irradiated with ultraviolet rays. (11) A method for erasing a latent image of a charge-holding medium placed opposite to a photoreceptor and on which an electrostatic latent image has been formed by voltage application exposure, the method comprising: bringing a conductive member into contact with the surface of the charge-holding medium and scanning the surface; A method for erasing a latent image on a charge retention medium, characterized by: (12) A charge retention method for erasing a latent image of a charge retention medium disposed facing a photoconductor and on which an electrostatic latent image has been formed by voltage application exposure, the method comprising spraying vapor onto the surface of the charge retention medium. Method for erasing latent images on media.