JPH0128378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method, and more particularly to an image forming method for forming a polarization pattern using a difference in voltage distribution between variable resistance layers of a photoconductive layer.

Conventionally, an electrophotographic photoreceptor has been used as an image forming member using an electrical method. A typical configuration of a photoreceptor used in the most common electrophotographic process, that is, a process in which an electrostatic image is formed by charging and imagewise exposure, is one in which a photoconductive layer is formed on a support. It is. An electrostatic image is generally formed by charging the surface of a photoreceptor by corona discharge, and then selectively dissipating the charges in the exposed areas by imagewise exposure. This electrostatic image is developed with toner charged with a polarity opposite to that of the electrostatic image, and is transferred onto transfer paper. It has been pointed out that this type of electrophotographic process requires wires and shield cases to perform corona charging, as well as high voltage to generate corona discharge, making it difficult to make the equipment more compact. .

On the other hand, conventionally known electrophotographic photoreceptors that can be easily made compact have also been proposed. As a representative example, JP-A No. 48-68238
Publication No. 150342, Japanese Patent Publication No. 150342, Japanese Patent Publication No. 1983-1503-
Examples include photoreceptors disclosed in JP-A No. 1027, JP-A-54-61534, and JP-A-54-61537. These photoreceptors do not require corona charging and are capable of forming potential images that can be produced by charged toner. Image exposure is performed by applying a voltage to the photoconductive layer on which electrodes are provided, and a potential image is created by creating a difference in distributed voltage between exposed and unexposed areas with respect to the applied voltage. It forms the However, in the process of forming this potential image, a change in the resistance of the photoconductive layer causes a voltage change on the surface of the photoreceptor, thereby forming a developable potential image. , it is necessary to apply voltage to the photoreceptor, image exposure, and development processing at the same time, which entails restrictions in terms of process or equipment.

The main object of the present invention is to provide an image forming method that is free from such restrictions, that is, image exposure and development can be performed sequentially.

Another object of the present invention is to provide a method for forming a storable polarization pattern corresponding to an original image.

The image forming method according to the present invention has a photoconductive layer provided with a patterned electrode, a patterned insulating layer covering the patterned electrode, and a patterned opaque layer on a conductive layer, and a polarized layer is provided on the photoconductive layer. A large number of discontinuous isolated conductors are provided on the polarized layer, and a patterned electrode, a patterned insulating layer, and a patterned opaque layer are arranged corresponding to the isolated conductors, and the polarized layer A patterned electrode and a photoconductive layer are provided below in contact with each other, and the patterned electrode is covered with a patterned opaque layer provided on the conductive layer side, while an isolated conductor is covered with the patterned opaque layer. Image exposure is performed from the conductive layer side with a voltage applied to the patterned electrode and the conductive layer for the image forming member whose portion is not covered, and the polarization state in the exposed area and the non-exposed area is made different to form a polarization image with respect to the original image. After image exposure, a voltage is applied to the patterned electrode and the conductive layer to form a potential image corresponding to the polarization image on the surface of the isolated conductor.

A typical configuration of an image forming member used in the image forming method according to the present invention is shown in FIG. In the image forming member shown in FIG. 1, a transparent conductive layer 2 is laminated on a transparent support 1, and a patterned opaque layer 3 is further formed, on which a photoconductive layer 4 and a patterned insulating layer 6 are formed.
and a patterned electrode 5, on which a polarized layer 7 having discontinuous isolated conductors 8 on its surface is formed. The transparent support is formed from a synthetic resin film or sheet, glass, ceramic, or the like. For example, the transparent conductive layer is
If the support is glass, its surface is conductive treated with In ₂ O ₃ or SnO ₂ , or if the support is a synthetic resin film such as polyimide film, Al,
Ag, Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb,
It is formed using metals such as Ta, V, Ti, Pt, etc. by vacuum evaporation, electron beam evaporation, sputtering, etc. The patterned opaque layer is provided to prevent the transparent conductive layer and the patterned electrode from being connected to each other in the exposed portion of the image forming member during image exposure by the photoconductive layer in a low resistance state, It is formed at a position corresponding to the pattern electrode. The patterned opaque layer is made of, for example, C,
It is formed using materials such as Cr, Ag, Au, Al, Ni, Fe, or gelatin mixed with black pigment by photo etching, mask vapor deposition, etc. The photoconductive layer is made of S, Se, Si, PbO,
It is formed by vacuum deposition of an inorganic photoconductive material such as an alloy or intermetallic compound containing S, Se, Te, As, Sb, etc. In addition, when using the sputtering method, Si,
A photoconductive layer can also be formed by depositing a high melting point photoconductive substance such as ZnO, OdS, CdSe, TiO ₂ on the support. In addition, when forming a photoconductive layer by coating,
Organic photoconductive materials such as polyvinylcarbazole, anthracene, and phthalocyanine, dye-sensitized or Lewis acid-sensitized versions of these materials, and mixtures thereof with insulating binders can be used. Also
Mixtures of inorganic photoconductors such as ZnO, CdS, TiO ₂ , PbO, etc. with insulating binders are also suitable. Note that various resins are used as the insulating binder.
FIG. 2 shows an isolated conductor 8 from the image holding member of FIG.
2 is a plan view of the image holding member with the polarized layer 7 removed, showing the shape of the patterned electrode 5. FIG.
That is, the pattern electrode 5 has a stripe shape, and the photoconductive layer 4 is also exposed in a stripe shape. Further, the patterned insulating layer 6 also has a striped shape sandwiching the patterned electrode 5. The pattern electrode is made of, for example, Cr, Ni, Fe, Al, Au, Ag,
It is formed from Pd, C, etc. The insulation layer is
For example, it is formed from epoxy resin, vinyl chloride resin, silicone resin, vinyl acetate resin, polyparaxylylene resin, polyethylene resin, urethane resin, acrylic resin, etc. A polarized layer is a ferroelectric material whose polarization direction is not the same under normal conditions but is microscopically polarized, or which is not polarized under normal conditions but becomes polarized by applying an electric field or an electric field and light. It is formed from a persistently polarizable material that maintains its polarized state even after the electric field or electric field and light are removed. As a ferroelectric material,
BaTiO ₃ , PLZT (PbxLa _1-x ) (Zry Ti _1-y ) O ₃ (Ox, y1), Borasite compound
Me _{3 B 7 O 13 X , Me : Divalent} metal lithium acid
LiTaO ₃ , potassium thallate KTaO ₃ and the like are used. As persistent polarizable substances, ZnS,
CdS, ZnO, ZnxCd _1-x S (however, 0<x<1),
CdSe, etc. are used. An isolated conductor is a discontinuous island-shaped conductor, and is an important conductor that becomes a pixel of an image to be formed. The shape of the isolated electrode is
As shown in the plan view of the figure, it is an isolated rectangle. The isolated conductor can be formed by various methods, but the typical manufacturing method is vapor deposition and chemical etching using photoresist. In this method, a material that forms an isolated conductor on the surface of the spontaneously polarized layer, such as In ₂ O ₃ ,
Metal oxides such as SnO ₂ , Al, Ag, Pb, Zn, Ni,
Various metals such as Au, Cr, Mo, In, Nb, Ta, U, Ti, and Pt are formed into layers on the spontaneous polarization layer by evaporation, electron beam evaporation, sputtering evaporation, or the like. Next, an island-shaped masking pattern is formed using a photoresist, and then a layer such as In ₂ O ₃ is selectively etched away using a predetermined etching solution such as acid or alkali, and then the masking pattern of the photoresist is removed. can form an isolated conductor. As the photoresist, any conventionally commonly used materials can be used. For example, as a commercially available product, product name: KPR (Kodak photo resist,
Manufactured by Kodak...Developer: methylene chloride, trichlene, etc.), product name: KMER (Kodak Metal
Etch Resist, made by Kodatsuku...Developer: xylene,
Triclean, etc.), Product name: TPR (manufactured by Tokyo Ohka...
Developer: xylene, trichlene, etc.), Product name: Situpre AZ1300 (manufactured by Situpre...Developer: alkaline aqueous solution), Product name: KTFR (Kodak Thin
Film Resist, manufactured by Kodatsu...Developer: xylene, trichlene, etc.), Product name: FNRR (Fuji Pharmaceutical...Developer: Chlorocene), Product name: FPER
(Fuji Photo Etching Resist, manufactured by Fuji Photo Film...Developer: Triclean), Product name: TESH
DOOL (manufactured by Okamoto Chemical Co., Ltd., developer: water), and product name: Fujiresist 7 (manufactured by Fuji Pharmaceutical Co., Ltd., developer: water). After use, the mask can be removed using triclene, methylene chloride, AZ Remover (trade name, manufactured by Shippray), sulfuric acid, or the like.

The isolated conductor can also be formed by depositing an isolated conductor-forming material on the polarized layer through a mask having an island-shaped opening, and then removing the mask.

The size of each component of the image forming member is determined as appropriate, but is generally as follows. The thickness of the photoconductive layer is 1μ to 100μ, the stripe width of the pattern electrode is 1μ to 50μ, the thickness of the polarization layer is 5 to 500μ,
The area of one isolated conductor is suitably 1 μ ² to 0.1 mm ² .

A typical method of forming an image using the imaging member shown in FIG. 1 is illustrated in FIGS. 4-6. First, as shown in FIG. 4, a voltage 9 is applied between the transparent conductive layer 2 and the patterned electrode 5.
The magnitude of this voltage is set to a value that does not change the polarization state of the polarization layer 7 in a dark place, that is, in a state where the photoconductive layer does not have a low resistance. Under such voltage application conditions, image exposure is performed as shown in FIG. The original image 10 has a dark area 11 and a bright area 12, and by performing light irradiation 13, the light that has passed through the bright area 12 is transmitted between the patterned opaque layers 3 14, and the photoconductive layer in this area is 4 to lower resistance. As a result, in the exposed area, most of the voltage 9 is applied to the polarized layer, which exceeds the coercive electric field of the polarized layer and the polarized state becomes directional as shown by arrows 15 and 16. , a polarization image corresponding to the original image is formed. Next, as shown in FIG. 6, a voltage 17 smaller than the coercive electric field of the spontaneously polarized layer (the minimum electric field necessary to change the direction of polarization) is applied. Here, the voltage applied on the polarized layer is E,
If the charge density applied to the polarized layer is D, the dielectric constant of the polarized layer is ε, and the magnitude of polarization is P, then in the non-exposed area D=εE and in the exposed area D=εE+P. Therefore, the amount of charge on the isolated conductor differs by P between the exposed portion and the non-exposed portion. Further, the effective capacitance C _F of the polarized layer at this time is expressed as C _F = ∂D/∂V. V is the magnitude of voltage 17. D
Since the exposed part is larger, the capacitance C _FD of the non-exposed part of the polarized layer and the capacitance C _FL of the exposed part are C _FD <C _FL .

Further, when the potential of the isolated conductor is V _O and the capacitance of the photoconductive layer is C _P , V _O is given by V _O =C _F /C _F +C _P V . By the way, since C _FD < C _FL ,
The potential V _OD in the non-exposed part of the isolated conductor and the potential V _OL in the exposed part satisfy V _OD <V _OL , and a potential image corresponding to the original image is formed. Therefore, by applying an ordinary electrophotographic developer in the state shown in FIG. The developer adheres to form a visible image, which is transferred and fixed onto transfer paper or the like as required. After image exposure as shown in Figure 5, the image is stored as a change in the polarization state of the polarized layer, and as shown in Figure 6, a voltage is applied to form a potential image. The processing for developing can be carried out after an arbitrary period of time (for example, 24 hours) after image exposure.

The typical process of the image forming method according to the present invention has been described above, but other embodiments are also possible. For example, the polarity of the voltage applied to the image holding member can be arbitrarily selected.
In particular, the polarity and magnitude of the voltage during development shown in FIG. 6 may be determined as appropriate so as to produce the necessary difference in potential between the exposed and non-exposed areas in the isolated conductor. .

The image forming member according to the present invention may also have other configurations in addition to the configuration shown in FIG. 1. Note that both the patterned insulating layer 6 and the patterned opaque layer in FIG. This is a pattern member for preventing this. Further, the shape of the isolated conductor can be arbitrarily determined, such as circular or triangular. Furthermore, the patterned electrodes, patterned insulating layer, patterned opaque layer, etc. can also be formed into arbitrary shapes such as dots, meshes, and combs. Furthermore, when image exposure is performed from the side of the isolated conductor, the transparent support and the transparent conductive layer do not need to be transparent. The support may be omitted if necessary.

EXAMPLE In ₂ O ₃ is electron beam evaporated to a thickness of about 1000 Å on a transparent glass substrate, and then heat treated in an oxygen gas atmosphere to form a transparent conductive layer. A mask was placed on top of the layer and Cr was evaporated to a thickness of about 500 Å using an electron beam to form a band-shaped opaque layer with a width of 30 μm and an interval of 10 μm. On top of this, an amorphous Si film with a thickness of about 5 μm was formed as a photoconductive layer by high-frequency glow discharge at 1 MHz in a H ₂ gas atmosphere of 0.1 Torr.
On top of that, UV-curable urethane/acrylic resin is applied to a thickness of approximately 5 μm, and only the resin layer corresponding to the patterned opaque layer is irradiated with UV rays and cured using a masking method, and the unexposed areas are cured. was removed using methyl ethyl ketone solvent to form a patterned insulating layer. Using a mask, band-shaped patterned electrodes as shown in FIG. 2 with a width of about 10 .mu.m and an interval of 30 .mu.m as shown in FIG. 2 are formed thereon to a thickness of 500 .ANG. by vacuum evaporation of Al using a resistance heating method. On top of this, a polarized layer of about 10 μm thick was formed using BaTiO ₃ powder by electron beam heating and vacuum evaporation. A mask with a pattern structure as shown in Fig. 3 is placed on top of the mask, and Al is vacuum-deposited by resistance heating to form an isolated Al conductor with a thickness of approximately 1500 Å (area a x a = 30 μ x 30 μ, b = 10 μ). was formed.

An imaging member was thus formed. Approximately
An AC voltage of 600V was applied, and the voltage was gradually reduced. As a result, the polarizations of the polarized layers completely canceled each other out. After this, about 300V in the opposite direction.
Apply voltage. At this strength, polarization does not reverse. This is because the resistance of the photoconductive layer is sufficiently high in the dark, so about half of the applied voltage is absorbed by the photoconductive layer, so the electric field necessary for polarization reversal is not built up in the polarized layer. by. Here, when an image is exposed from the transparent conductive layer side as shown in Fig. 5, the resistance of the photoconductive layer becomes small in the exposed area, and most of the voltage is applied to the polarization layer, so the polarization electric field required by the polarization layer (i.e. (coercive electric field) and polarization reversal occurs. On the other hand, since there is no change in the non-exposed area, polarization reversal does not occur. Therefore, corresponding to the bright and dark areas of the image, in the bright areas, the direction of polarization is aligned with the direction of the electric field, and in the dark areas, the polarizations cancel each other out. This state does not change even if the electric field is removed or image exposure is stopped.

When an electric field below the polarization reversal is again applied to a state where the polarization directions are arranged in different directions according to the polarization image, the potential on the isolated conductor will differ depending on the polarization state. Actually, as shown in Figure 6
When a voltage of 200V is applied between the transparent conductor and the patterned electrode, approximately
A potential image of 80V and approximately 180V in the bright area was obtained. In this state, when a liquid developer containing positively charged toner was sprinkled onto the isolated conductor, a good image was formed. When the image was transferred onto paper from this state, an image was formed on the paper. Further, residual toner on the isolated conductor was removed and left as it was for one day. After that, when a voltage of 200V was applied again as described above, a similar potential contrast was obtained. When liquid developer was sprinkled over it again, a good image was formed again. Even after repeating this process over 100 times, the same image was obtained each time. In order to use this photoreceptor again, return to the method shown in Figure 4, apply an alternating current electric field, gradually reduce the voltage, and heat the photoreceptor to above the Kyuri point of the polarization layer (i.e., above 120°C in this case). By heating and then cooling, the polarization is aligned in all directions and the effect is not radiated.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the imaging member used in the present invention. 2 is a plan view of the patterned electrode surface of the imaging member of FIG. 1; FIG. 3 is a plan view of the surface of the imaging member of FIG. 1; FIG. 4 to 6 show one embodiment of the image forming method according to the present invention,
FIG. 4 shows a voltage application step, FIG. 5 shows an image exposure step, and FIG. 6 shows a potential image forming step. DESCRIPTION OF SYMBOLS 1... Transparent support, 2... Transparent conductive layer, 3... Patterned opaque layer, 4... Photoconductive layer, 5... Patterned electrode, 6... Patterned insulating layer, 7... Polarized layer, 8... Isolated conductor.

Claims (1)

[Claims] 1. A photoconductive layer having a patterned electrode, a patterned insulating layer covering the patterned electrode, and a patterned opaque layer on the conductive layer, and a polarization layer on the photoconductive layer. A large number of discontinuous isolated conductors are provided on the polarized layer, and a patterned electrode, a patterned insulating layer, and a patterned opaque layer are arranged corresponding to the isolated conductors. A patterned electrode and a photoconductive layer are provided below in contact with each other, and the patterned electrode is covered by a patterned opaque layer provided on the conductive layer side, while an isolated conductor is partially covered by the patterned opaque layer. For the uncovered image forming member, image exposure is performed from the conductive layer side with a voltage applied to the pattern electrode and the conductive layer, and the polarization state in the exposed area and the non-exposed area is made different to form a polarization image with respect to the original image. Then, after image exposure,
An image forming method characterized by applying a voltage to a patterned electrode and a conductive layer to form a potential image corresponding to a polarization image on an isolated conductor surface. 2. The image forming method according to claim 1, which develops a potential image.