JPH04362916A - Information recording medium and method for recording and reproducing electrostatic information - Google Patents

Abstract

PURPOSE:To obtain a reutilizable information recording medium capable of recording and storing electrostatic information as visible information and capable of reproducing recorded information after the lapse of an arbitrary time. CONSTITUTION:An information recording layer made of resin 11 contg. a dispersed and fixed liq. crystal phase 12 is formed on an electrode layer 13 to obtain an information recording medium. The refractive index of the resin 11 is nearly equal to that of the liq. crystal oriented by an electric field.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an information recording medium in which electrostatic information can be recorded and stored as visible information using a resin body in which a liquid crystal phase is dispersed and fixed, and can be reproduced at any time, and an information recording and reproduction method thereof. Regarding.

0002

2. Description of the Related Art Liquid crystal display elements have come to be used in displays for office automation equipment such as word processors and laptop computers. These devices have a liquid crystal layer sandwiched between transparent substrates such as glass or plastic substrates provided with transparent electrode films, and use a single matrix or an active matrix to display information such as images by applying a voltage between both electrodes. It is to be displayed. Examples of this method include the typical TN type and STN type, a dynamic scattering type that operates by the current effect, a type that utilizes cholesteric-nematic phase transition, and a more recent type that uses a composite of polymer and liquid crystal. Elements in which nematic liquid crystals are dispersed and fixed in a polymer resin body can be manufactured by applying a voltage and aligning the orientation of the liquid crystal substance in the direction of voltage application by matching the ordinary refractive index of the liquid crystal substance and the refractive index of the polymer resin body. When no voltage is applied, the alignment of the liquid crystal material becomes irregular and light is scattered at the interface between the liquid crystal material and the polymer resin, or within the dispersed and fixed liquid crystal phase, resulting in an opaque state. , which is displayed by being opaque. As a liquid crystal display element with nematic liquid crystal dispersed and fixed in a polymer resin body, the area can be increased, and the response time, especially the fall time, is short.
Due to its features such as high light utilization efficiency without the need for polarizing plates, wide and uniform viewing angle, and flexibility, its use in window light control sheets and projection displays has been reported in recent years. .

[0003] As a projection type display or computer display, etc., the fall time is 1 to 3.
The most commonly used TN type or S type, which is as short as 0ms.
It has the advantage of being shorter than a TN type display.

[0004] Normally, a liquid crystal display element in which nematic liquid crystal is dispersed and fixed in a polymer resin body is sandwiched between electrodes and an alternating current voltage is applied thereto, and display and erasure are performed by turning the voltage ON and OFF. At this time, there are reports that a slight hysteresis occurs in the voltage vs. light transmittance, and there is a difference in transmittance when the applied AC voltage increases and decreases. Then, it returns to its initial transmittance, that is, its opaque state.

[0005] A common method for displaying information such as images is to display them by sandwiching them between matrix electrodes and turning each pixel on and off. When forming a composite film of molecules and liquid crystal, for example, there is a method that uses an ultraviolet curing polymer material and irradiates ultraviolet rays in the form of an image, but all of them flash fixed information.

On the other hand, as materials with memory properties,
There is a method using cholesteric-nematic phase transition, but this method requires a sandwich structure in which a vertical alignment film is sandwiched between transparent electrodes formed on the electrodes. Therefore, in this case, an electrode structure is required.

[0007]

[Problems to be Solved by the Invention] The present invention uses a resin body in which a liquid crystal phase is dispersed and fixed on an electrode layer to record and store electrostatic information as visible information, which can be reproduced at any time and reused. The object of the present invention is to provide a possible information recording medium and an information recording/reproducing method thereof.

[0008]

[Means for Solving the Problems] The information recording medium of the present invention is an information recording medium in which an information recording layer is provided on an electrode layer, and the information recording layer is a resin body in which a liquid crystal phase is dispersed and fixed,
It is characterized in that the optical refractive index of the resin body is selected so that the optical refractive index of the liquid crystal substance in a state where it is oriented by an electric field is almost the same.

Further, the information recording medium of the present invention has the above-mentioned information recording layer provided on the electrode layer via a charge injection prevention layer,
and/or a charge retention layer is provided on the information recording layer.

[0010] Furthermore, the electrostatic information recording and reproducing method of the present invention includes:
An information recording layer, which is a resin body in which a liquid crystal phase is dispersed and fixed, and is selected so that the optical refractive index of the resin body and the optical refractive index in a state in which the liquid crystal substance is oriented by an electric field is approximately matched, is placed on the electrode layer. The provided information recording medium and a photoreceptor having a photoconductive layer provided on an electrode layer are placed facing each other, and a voltage is applied between both electrodes while exposing the photoreceptor or the information recording medium to electrostatic information recording. The electrostatic information is recorded and saved as visible information, and can be reproduced at any time.

FIG. 1 is a diagram for schematically explaining the cross section of the information recording medium of the present invention, in which (a) is a schematic diagram before information is recorded, and (b) is a schematic diagram after information is recorded. A diagram for explaining the state of information recording and reproduction on a recording medium, and FIG. 10(c) is a diagram showing another example of the information recording medium of the present invention, in which 3 is an information recording medium, 11 is a resin body, 12 is a liquid crystal phase, 13 is an electrode layer, 14 is a charge retention layer, 15 is a support, and 16 is a charge injection prevention layer.

As shown in FIG. 1(a), the information recording layer includes:
A low-molecular liquid crystal material 12 is dispersed and fixed in a resin body 11, and nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or a mixture thereof can be used as the liquid crystal material. For example, the following nematic materials can be used.

[0013]

[Chemical formula 1]

[0014]

[Case 2]

[0015]

[Chemical formula 3]

[0016]

embedded image Furthermore, by mixing these nematic liquid crystals with smectic liquid crystals or cholesteric liquid crystals, memory properties can be improved.

[0017] When selecting a liquid crystal material, it is preferable to use a material with a large anisotropy of refractive index because it provides better contrast.

Further, as the resin body, solvent-soluble resins that are compatible with the same solvent as that of the liquid crystal material, such as methacrylic resin, polyester resin, polystyrene resin, etc., and copolymers mainly composed of these resins are used. , or radiation-curable resins that are compatible with the liquid crystal material in the form of monomers or oligomers, such as acrylic esters and methacrylic esters, or thermosetting resins such as epoxy resins,
Silicone resin or the like can be used. Additionally, a mixture of polyvinyl alcohol and a liquid crystal material and microcapsules may also be used.

The information recording layer of the present invention must be selected so that the optical refractive index of the resin body and the optical refractive index of the oriented liquid crystal are approximately equal. Reflection and scattering occur at the interface between the recording material and the resin body, making it impossible to obtain a transparent state during recording.

The mixing ratio of the liquid crystal material and the resin body is preferably such that the content of the liquid crystal material is 10% to 80% by weight, preferably 30% to 60% by weight, and less than 10% by weight. If it exceeds 80% by weight, the transparency is high when unrecorded and the contrast is low even when the liquid crystal phase is oriented after information is recorded, and if it exceeds 80% by weight, phenomena such as bleeding of the liquid crystal occur, which is not preferable.

In the case of a solvent-soluble type, the information recording layer is formed by dissolving the resin body and liquid crystal material in a solvent, and applying the solution onto the electrode layer using a general method such as a blade coater, roll coater, or spin coater. It is thought that when the solvent is dried, the liquid crystal material solidifies and the liquid crystal material undergoes phase separation, and is dispersed and fixed as a liquid crystal phase with a particle size of about sub-μm. The thickness of the information recording layer is preferably 1 μm to 40 μm after drying.

[0022] When a solvent-soluble type or a thermosetting type resin is used, it is necessary to heat the liquid crystal material at a temperature below the temperature at which it changes to a so-called isotropic phase, which is a random state. If the resin is dried and solidified in a state that has transitioned to an isotropic phase, liquid crystallinity will not be obtained and the electro-optical effect will not be exhibited. This is thought to be because if the temperature is high at the time of drying, a sufficient phase separation state cannot be obtained, and the resin body and liquid crystal are dried in a state in which they are mutually dissolved.

The material of the electrode layer 13 has a specific resistance value of 106
It is not limited as long as it is Ω·cm or less, and examples include metal conductive films, inorganic metal oxide conductive films, and organic conductive films such as quaternary ammonium salts. Such electrodes are formed on a support by methods such as vapor deposition, sputtering, CVD, coating, plating, dipping, and electrolytic polymerization. In addition, the film thickness needs to be changed depending on the electrical properties of the material constituting the electrode and the applied voltage during information recording. For example, ITO
The film has a thickness of about 100 to 3000 Å, and is formed on the entire surface between the information recording layer or in accordance with the formation pattern of the information recording layer.

Information is recorded on the information recording medium of the present invention formed in this manner, as shown in FIG. 1(b), when information charges are applied to the surface of the information recording layer, there is This is done by aligning the liquid crystal layer present in the information recording area in the direction of the electric field due to the electric field formed in the information recording area. Since they have the same optical refractive index, light A is transmitted, whereas light B is scattered in areas where no information is recorded, providing contrast with the information recording area.

The support 15 supports the information recording medium with strength, and does not need to be provided when the information recording layer has support properties, but it has a certain degree of strength that can support the information recording layer. As long as it has, there are no particular restrictions on its material and thickness; for example, a flexible plastic film, or a rigid body such as glass or a plastic sheet can be used. Specifically, when the information recording medium takes the form of a flexible film, tape, disk, or card, a flexible plastic film is used; when strength is required, a rigid sheet, glass, etc. Inorganic materials etc. are used.

In the case of reproduction by transmission, a layer having an anti-reflection effect may be laminated on the other side of the support, if necessary, or the support may be coated to a thickness that can exhibit an anti-reflection effect. Antireflection properties may be imparted by adjusting the above or by combining the two.

The information recording medium of the present invention is one in which a resin body in which a liquid crystal substance is dispersed and fixed is laminated on an electrode layer, and electrostatic information is recorded and stored in a visualized state by the orientation of the liquid crystal. In conventional TN-type and STN-type liquid crystal cells in which liquid crystal is sandwiched between electrodes, or in cells in which a liquid crystal phase is dispersed and fixed in a polymer resin, the cell returns to its original state when the voltage is removed, and has no memory properties.

In the information recording medium of the present invention, information is electrostatically recorded on one surface of the information recording layer that does not have an electrode layer opposite to the electrode layer, thereby providing information with gradation. It can be recorded and saved. In addition, once recorded visible information is not erased even if the electrostatic charge is removed,
When information with gradation is recorded, the gradation reproducibility changes, but it has memory properties. The reason for this is unknown, but when the information recording medium of the present invention is sandwiched between electrodes and a DC voltage is applied, it does not exhibit memory properties and operates the moment a voltage is applied, just like a conventional liquid crystal cell. Due to dielectric relaxation, the transmittance returns to almost its initial state in a short time. Also, the moment the voltage is removed, it responds again, but returns to its initial state again. Therefore, the information recording medium in the present invention has an electrode layer on only one side. Therefore, the recording method in the present invention includes corona charging, which allows electrostatic recording on the surface of an information recording medium that does not have an electrode layer, and applying a voltage between both electrodes while facing the electrodes through an air gap. It can be recorded using air discharge or field emission based on Paschen's law. Among these, a method is preferred in which simultaneous exposure is performed while applying a voltage while the photoreceptor having a photoconductive layer is placed opposite to the photoreceptor through an air gap, and an image with gradation is recorded depending on the intensity of optical information.

This memory property can be improved by heating during recording. The heating temperature needs to be above room temperature and below the temperature at which the liquid crystal substance transitions to an isotropic phase. When heated above the isotropic phase, the information recording medium becomes transparent and the liquid crystal material does not exhibit liquid crystallinity. An appropriate heating temperature is preferably a temperature at which once a recorded medium is heated, it becomes cloudy and the recorded information returns to its original initial state. Although the details of this are unknown, it is thought that the memory property is expressed by the interaction between the phase-separated liquid crystal phase and the resin body interface, and the temperature at which the interfacial interaction disappears, that is, the critical temperature at which the interfacial interaction changes significantly. It is best to heat the sample to a temperature slightly lower than this temperature and then record the data while the interfacial interaction is large. Therefore, the heating temperature is appropriately set depending on the composition, composition ratio, etc. This interfacial interaction persists even after cooling and leaving for a while.

Furthermore, when recording is performed using the information recording medium of the present invention by applying a voltage through an air gap and an electrode on which a conductive layer is formed in a pattern, a line of the conductive layer of 6 μm and a line of a space of 6 μm is recorded. It was confirmed that resolution was achieved in the parts where the images were arranged alternately. The resolution and the film thickness of the information recording medium are closely related, but in the information recording medium of the present invention, the accuracy of the film thickness is precisely controlled during the coating of the information recording layer, so it is difficult to sandwich between the electrodes. It does not require a spacer to control the gap unlike traditional lamination or encapsulation methods, and no defects occur even when high-resolution information is recorded.

Furthermore, the visualized information once recorded is erased by heating it above a critical temperature at which the interaction between the polymer resin body and the dispersed and fixed liquid crystal phase changes significantly.
Can be reused.

The visualized information can also be erased by heating above the isotropic phase transition temperature of the liquid crystal phase, but in this case, it becomes transparent once, and when cooled it returns to its original opaque state.

[0033] Furthermore, in the information recording medium of the present invention,
By providing a charge retention layer on the surface of the information recording layer as shown in FIG. This makes it possible to electrically reproduce electrostatic information stored in the retention layer.

[0034] Such a charge retention layer is made of a highly insulating resin in order to suppress the movement of static charges, and is required to have insulating properties and transparency with a specific resistance of 1014 Ω·cm or more. As such resins, fluororesins such as polytetrafluoroethylene, fluorinated ethylene propylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, polyimide resins, polyether ether ketone resins, polyparaxylylene, etc. are used. A layer can be formed on the information recording layer by vapor deposition, sputtering, etc., or by dissolving it in a solvent and coating or dipping it. Alternatively, a layer may be formed by attaching a film of the above polymer via an adhesive or the like. The film thickness is preferably 1 μm to 40 μm.

[0035] Furthermore, a charge injection prevention layer may be provided between the electrode layer and the information recording layer.

The charge injection prevention layer prevents the injection of charges from the electrode layer, and has the effect of suppressing the injection of opposite charges on the electrode side and maintaining the electric field. This charge injection prevention layer can be made of the same material as the charge retention layer forming material, and is preferably laminated to a thickness that does not cause the charge tunneling phenomenon, at least 1000 Å or more.

Further, photoconductive fine particles or conductive fine particles may be contained in the charge retaining layer and/or the charge injection preventing layer.

Next, a method for recording and reproducing information on an information recording medium according to the present invention will be explained.

FIG. 2 is a diagram for explaining the information recording method, in which 1 is a photoreceptor, 5 is a photoconductive layer support, 7 is a photoreceptor electrode, 9 is a photoconductive layer, and 17 is a power source.

First, a layer of indium tin oxide (ITO) with a thickness of 1000 Å is placed on the photoconductive layer support 5 made of glass with a thickness of 1 mm.
), and a photoconductive layer 9 of about 10 μm is formed thereon to constitute the photoreceptor 1.

As shown in FIG. 1A, an information recording medium 3 is placed with respect to the photoreceptor 1 with a gap of about 10 μm in between.

Next, as shown in FIG. 3B, a voltage is applied between the electrodes 7 and 13 by the power source 17. In a dark place, the photoconductive layer 9 is a high resistance material.

In this state, when light 18 is incident from the photoreceptor 1 side, the photoconductive layer 9 in the area where the light is incident becomes conductive and becomes a low resistance material, and information charges are accumulated in the information recording layer. Orientation of the liquid crystal occurs at the charge accumulation site in the information recording layer. Furthermore, even if there is a uniform fog charge in advance, more charge accumulates in the area where the light is incident, so
Information can be recorded based on the contrast with the unexposed area.

[0044] Furthermore, as described above, when forming information charges, some liquid crystals operate at a low voltage, so when setting the applied voltage, the voltage distribution between the photoreceptor, air gap, and information recording medium must be adjusted. By appropriately setting the voltage distribution applied to the information recording layer, it is preferable to set the voltage distribution to the operating voltage range.

[0045] When recording on this information recording medium,
The memory properties of the information recording medium can be further improved by heating the information recording medium, for example, by passing an electric current through the electrode layer.

[0046] This information recording method enables planar analog recording and obtains alignment at the level of liquid crystal particles, so high resolution can be obtained similar to silver salt photography, and the exposure pattern is determined by the alignment of the liquid crystal phase. Visualized and retained.

Methods for inputting information to the information recording medium of the present invention include a method using a high-resolution electrostatic camera and a recording method using a laser.

The information light may be incident from the photoreceptor side or may be incident from the information recording medium side. First, a high-resolution electrostatic camera uses a photoreceptor 1 and an information recording medium 3 as a recording member instead of the photographic film used in a normal camera, and can also use a mechanical shutter. Electric shutters could also be used.

In addition, the optical information is separated into R, G, and B light components using a prism and a color filter, and is taken out as parallel light. Three sets of information recording media separated into R, G, and B can be used in one set.
Color photography can also be performed by forming frames or by arranging R, G, and B images on one plane so that one set constitutes one frame.

[0050] In the recording method using a laser, the light source is an argon laser (514.488 nm);
A helium-neon laser (633 nm) or a semiconductor laser (780 nm, 810 nm, etc.) can be used, and a voltage is applied to the photoreceptor and the information recording medium by bringing the surfaces of the photoreceptor and information recording medium into close contact with each other, or by facing each other at a fixed interval. In this state, laser exposure corresponding to image signals, character signals, code 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 recording such as characters, codes, and line drawings is performed by ON/OFF control of the laser light. Further, halftone dots are formed in an image by subjecting laser light to dot generator ON/OFF control. Note that the spectral characteristics of the photoconductive layer in the photoreceptor do not need to be panchromatic, but only need to be sensitive to the wavelength of the laser light source.

Information can be recorded on the information recording medium of the present invention not only by using a photoreceptor as described above, but also by corona charging, a pin electrode, an ion current head, an electron beam, or ion implantation. Information charges may be directly applied to the surface of the information recording layer during writing.

Information recorded by the alignment of liquid crystals is visible information that can be read visually, can be enlarged and read using a reflective projector, and can also be read by laser scanning or CCD. Information can be read with high precision by reading with reflected light or transmitted light.

[0053]

[Operations and Effects of the Invention] The information recording medium of the present invention has a recording layer in which liquid crystal is dispersed in a polymer, so that it can hold a low-molecular liquid crystal and easily obtain an electro-optic effect. Analog information can be recorded and stored in memory. Further, since the liquid crystal phase dispersed in the resin body is not oriented in the initial state, recorded information can be read by the contrast between scattered light and transmitted light without using a polarizing plate.

Further, in the information recording medium of the present invention, since the information recording layer can be made uniformly thin by coating technology, the gap between the information charge and the conductive layer can be made uniformly small, making it possible to produce a large area information recording medium. It is possible to record and reproduce high-resolution images. In addition, when no electric field is applied due to information charges, it is opaque due to light scattering, and when an electric field is applied, the liquid crystal phase is oriented, and by keeping its optical refractive index and the optical refractive index of the resin body almost the same, it is possible to record information. It is possible to make the part transparent, a polarizing plate is not required when reproducing information, and the optical system for reading can be simplified.

In the present invention, it has been discovered that memory properties can be obtained by dispersing and fixing a liquid crystal phase in a resin, but also a charge retention layer, a conductive layer and an information recording layer are provided on the surface of an information recording medium. By providing a charge injection prevention layer between them, the orientation of the liquid crystal phase in the information recording layer--the storage stability of visible information can be improved, and the permanence of information recording can be improved.

Furthermore, by providing a charge retention layer, it is possible to improve the retention of information charges themselves, and since electrostatic information can be reproduced electrically, information can also be reproduced optically and electrically. It is something that can be used.

Examples will be explained below.

[0058]

[Example 1] Cyanobiphenyl liquid crystal (manufactured by BDH)
E44, Δn=0.262, N-I transition 100℃)
0.2g and PMMA (manufactured by Mitsubishi Rayon Co., Ltd., BR
-80) 0.3 g in 1,2-dichloroethane to prepare a 10 wt% solution, and this solution was sputtered onto a 1 mm thick glass substrate to form an indium tin oxide (ITO) electrode into a 1000 Å film. Coat with a blade coater on the electrode of the glass substrate formed by laminating thick layers, and
It was dried in an oven maintained at 0° C. for 1 hour to produce an information recording medium of the present invention. The information recording layer was white and opaque, and had a thickness of 8 μm.

Similarly, an information recording layer with a thickness of 40 μm was formed, and when the cross section of the information recording layer from which the liquid crystal was extracted with a solvent was observed using an electron microscope (1000x magnification), as shown in FIG. The liquid crystal hole (the part that looks like a hole)
It was confirmed that there was phase separation.

[0060] The surface of the information recording medium thus produced was charged to +30V to +160V by corona charging,
FIG. 4 shows the results of measuring the optical density of the charged portion with respect to the amount of charge using a microdensitometer (manufactured by Konica). The vertical axis is the value of the difference from the optical density of the ITO-coated glass used.

As described above, it has been confirmed that the liquid crystal layer in the recording layer of the information recording medium of the present invention is oriented due to the surface charge, and that the orientation differs depending on the intensity of the electric field. I understand that it can be expressed.

When the information recording medium on which information was recorded was immersed in water or left at room temperature, the surface charge disappeared;
Even when the surface charge disappears, the transmittance shown in FIG. 4 is preserved, and it can be confirmed that the information stored in the information recording medium of the present invention has memory properties even in the absence of an electric field.
It was confirmed that the records themselves are permanent.

[0063] In addition, the information recording medium on which information is recorded is
When heated to ℃, transparency in the information recording area disappeared and it became white and opaque.

[0064]

[Example 2] The recording medium as produced in Example 1 and the recording medium were heated on a hot plate for about 70 minutes.
Two types of samples heated to 0.degree. C. were each charged to +150 V by corona charging.

The optical density of the charged part immediately after charging and after the information recording medium was soaked in water to remove the surface charge was measured using a microdensitometer, and the effect of heating before corona charging was investigated. . The measurement results are shown in the table below.

[0066]

[Table 1] Optical density: difference from the optical density of ITO glass. The optical density when OFF is 0.45. As can be seen from the table, heating the information recording medium before recording improves the memory performance. Ta. The heating temperature is preferably 60° C. or higher, and the effect is maintained for a while after heating and cooling to room temperature. Further, when the recording medium on which information was recorded was heated to 70° C., the information recording portion lost its transparency and became white and opaque. When the optical density at this time was measured, it was 0.45. This is equivalent to the optical density of this recording medium when it is not charged.

[0067]

[Example 3] (Production of photoreceptor) 15 parts by weight of p-diethylaminobenzaldehyde-N-phenyl-benzylhydrazone and 10 parts by weight of polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: Iupilon S-100) were used as charge transport materials. , dichloromethane:1,1,2-trichloroethane=4:6
A solution with a solid content of 17.8% was prepared using a mixed solvent of Apply with a gap thickness blade coater,
It was dried at 80° C. for 2 hours to form a charge transport layer with a thickness of 10 μm.

Next, the charge generating material is expressed by the following formula:

[0069]

[Chemical formula 5] 3 parts by weight of bisazo pigment and 1 part by weight of polyvinyl acetal resin
A solution was prepared by adjusting the solid content to 2% with a mixed solvent of dioxane: cyclohexane = 1:1, and coated on the charge transport layer using a blade coater with a 2 mil gap, and heated at 100°C. A charge generation layer of 0.3 μm was formed by drying for 1 hour to prepare a photoreceptor.

As shown in FIG. 2, this photoreceptor and the information recording medium produced in Example 1 were placed facing each other with a gap of 9 μm interposed therebetween, and a voltage of 750 V was applied between the electrodes of the photoreceptor and the information recording medium.
A gray scale was projected and exposed for 0.1 seconds, and the exposure amount and optical density of the information recording medium were measured in the same manner as in Example 1. The results are shown in FIG.

[0071] Thus, it was confirmed that the information recording medium of the present invention can similarly record information according to the exposure amount by electrostatic information recording opposed to the photoreceptor.

In addition, when a negative image of a silver halide photograph was projected and exposed instead of a gray scale, and the obtained information recording medium was read using a film scanner (manufactured by Nikon Corporation) and printed on a printer, a silver halide photograph was obtained. It was possible to reproduce a positive image with tonality corresponding to the negative image.

[0073]

[Example 4] A recording medium prepared in the same manner as in Example 1 was heated to about 70°C using a hot plate, and then a gray scale was projected and exposed in the same manner as in Example 3. The optical density of the recording medium was The measurement results are shown in FIG. 6 by circles. The result of measuring the optical density after immersing this recording medium in water to remove the surface charge is indicated by a black mark. Due to surface charge dissipation,
Although the transmittance decreases, the gradation according to the exposure amount (charge amount) is maintained.

[0074]

[Example 5] A recording medium prepared in the same manner as in Example 1 was heated to approximately 70°C using a hot plate, and then charged to +200V by corona charging. 7. If the storage temperature of the recording medium is 23℃, mark ○, if the storage temperature is 33℃, mark 3.
The case where the temperature is 8°C is indicated by a □ mark. When the horizontal axis was plotted as a logarithm, straight lines with different slopes were obtained at each temperature.

In the figure, the optical density (R) on the vertical axis is Ct - C
off /Co −Coff × 100, and C
t is the optical density at time t, Co is the optical density immediately after charging, and Coff is the optical density when the voltage is OFF.

[0076]

Example 6 Gold was deposited on the surface of a recording medium prepared in the same manner as in Example 1 to form an electrode. A DC voltage of 200 V was applied for 0.1 sec to both ends of this medium, and a He-Ne laser (
633 nm) was detected by a photodiode. The measurement results are shown in FIG. The vertical axis of the figure is the electromotive force (V) of the photodiode, and the horizontal axis is time (sec).

The transmittance of the recording medium increases when a voltage is applied (t=0), but since the resistance of the liquid crystal part is lower than that of the binder resin, the effective voltage applied to the liquid crystal decreases with the passage of time. The transmittance of the medium decreases (0≦t≦0.1
). When the DC voltage is OFF (t = 0.1), the voltage applied to the binder resin is redistributed to the liquid crystal part, and the transmittance increases momentarily, but the transmittance immediately decreases, and the transmittance remains the same as before voltage application. Return to In this way, when the recording medium shown in Example 1 has electrodes on both sides and a DC voltage is applied, the transmittance decreases due to dielectric relaxation inside the medium even when voltage is applied, and the transmittance decreases as soon as the voltage is turned off. , the state returned to the same state as before the voltage was applied.

[0078]

[Example 7] A recording medium produced in the same manner as in Example 1 was placed facing a patterned electrode in which 6 μm lines were arranged with a 6 μm space between them on glass, and both ends of the recording medium electrode and the pattern electrode were placed facing each other. When a DC voltage of 750 V and 0.1 sec was applied to the recording medium, it was confirmed that lines and spaces of 6 μm were resolved on the recording medium. Also,
It was confirmed that the resolution was maintained even after the recording medium was immersed in water to remove the electric charge.

[0079]

[Example 8] On the information recording layer formed in the same manner as in Example 1, a 5% fluorine-based solution of fluororesin (trade name: CYTOP, manufactured by Asahi Glass Co., Ltd.) was spin-coated (1500 rpm:
After applying it for 30 seconds) and leaving it at room temperature for 1 day,
Drying in a vacuum oven at 0°C reduces the film thickness to approximately 0.5μ.
A charge retention layer of m was formed to produce an information recording medium of the present invention.

When electrostatic information was recorded on this information recording medium in the same manner as in Example 3, it was confirmed that it could be recorded in the same manner as in Example 3.

Even after this information recording medium was left at room temperature for 20 days, a visible image was maintained, and information charges could also be read with a surface electrometer.

[0082]

[Example 9] On the information recording layer formed in the same manner as in Example 1, a 20% hexane solution of rosin ester resin (manufactured by Rika Hercules Co., Ltd., Stevelite Ester 10) was applied by spin coating (2000 rpm, 30 seconds). After drying in an oven at 60℃ for 2 hours, the film thickness was about 0.7μ.
A charge retention layer of m was formed. Next, a-Se fine particles were deposited on the surface of the charge retention layer using a vacuum deposition machine (VPC-410, Shinku Kiko Co., Ltd.) under the following conditions.

First, the above-mentioned medium was fixed to a heating substrate holder in a vacuum chamber so that its glass surface was in contact with the medium, and the substrate holder was heated to 70° C. under a vacuum of 6 torr, and a-Se was heated by resistance heating. was provided in the form of fine particles near the surface of the charge retention layer to produce an information recording medium of the present invention.

Next, when electrostatic information was recorded on this information recording medium in the same manner as in Example 3, the same recording as in Example 3 could be performed.

It was also found that even after this information recording medium was left at room temperature for 20 days, the visible image was maintained and the surface potential could be reproduced using a surface electrometer and was maintained.

[0086]

[Example 10] A fluororesin (product name: Cytop, Asahi Glass Co., Ltd. Co., Ltd.'s 5% fluorine-based solution was applied by spin coating (1500 rpm: 30 seconds), left at room temperature for 1 day, and then dried in an oven at 150°C for 3 hours to achieve a film thickness of approximately 0. A layer of 5 μm thick is formed, the surface thereof is subjected to plasma treatment, and then a cyanobiphenyl liquid crystal (E44 manufactured by BDH, Δn=0.262, N-I transition 100
°C) 0.2g and PMMA (manufactured by Mitsubishi Rayon Co., Ltd., B
A solution prepared by dissolving 0.3 g of R-80) in 1,2-dichloroethane to prepare a 10% by weight solution was coated with a blade coater, and dried in an oven kept at 80°C for 1 hour to give a white opaque color. An information recording medium layer having a film thickness of 8 μm was formed to produce an information recording medium of the present invention.

When electrostatic information was recorded on this information recording medium in the same manner as in Example 3, it was confirmed that it could be recorded in the same manner as in Example 3.

[0088] Further, a 5% fluorine-based solution of fluororesin (product name: CYTOP, manufactured by Asahi Glass Co., Ltd.) was spin-coated (1500 rpm:
After applying it for 30 seconds) and leaving it at room temperature for 1 day,
Drying in a vacuum oven at 0°C reduces the film thickness to approximately 0.5μ.
An information recording medium of the present invention was prepared by forming a charge retention layer of m, and electrostatic information was recorded in the same manner as in Example 3, and it was confirmed that it could be recorded in the same manner as in Example 3.

It was also found that even after this information recording medium was left at room temperature for 20 days, the visible image was maintained and the surface potential could be reproduced using a surface electrometer and was maintained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the information recording medium of the present invention, FIG. 1(a) is a schematic diagram before information recording, and FIG. 1(b) illustrates the state of information recording and reproduction of the information recording medium after information recording. FIG. 1(c) is a diagram showing another example of the information recording medium of the present invention.

[Figure 2] Diagram for explaining an information recording method using a photoreceptor,

FIG. 3: Electron micrograph showing the particle structure of the liquid crystal phase in the cross section of the information recording layer of the information recording medium of the present invention;

[Figure 4
] A diagram for explaining the relationship between the charging potential on the information recording medium of the present invention and the optical density in the information recording part,

[Figure 5]
A diagram for explaining the relationship between the exposure amount and the optical density in the information recording section by electrostatic information recording using a photoreceptor,

FIG. 6 is a diagram for explaining the record retention property due to heating operation before information recording on the information recording medium of the present invention, and the influence on the record retention property depending on the presence or absence of surface charge in the information recording part,

FIG. 7 is a diagram illustrating the influence of the storage temperature of the information recording medium on the record retention property due to the heating operation before recording information on the information recording medium of the present invention;

FIG. 8 is a diagram illustrating the results of a study on the information recording properties of an information recording medium of the present invention in which an electrode layer is provided on the surface of the information recording layer.

[Explanation of symbols]

1 is a photoreceptor, 3 is an information recording medium, 5 is a photoconductive layer support,
7 is a photoreceptor electrode, 9 is a photoconductive layer, 11 is a resin body, 12 is a liquid crystal phase, 13 is an electrode layer, 14 is a charge retention layer, 15 is a support, 16 is a charge injection prevention layer, 17 is a power source, 18 is pattern exposure light, A is transmitted light, and B is reflected light.

Claims (5)

[Claims] [Claim 1] Consisting of a resin body in which a liquid crystal phase is dispersed and fixed on an electrode layer, the resin body is selected so that the optical refractive index of the resin body and the optical refractive index of the liquid crystal substance in a state where it is oriented by an electric field almost match. An information recording medium characterized in that information recording layers are laminated. 2. The information recording medium according to claim 1, wherein the information recording layer is provided on the electrode layer via a charge injection prevention layer, and/or a charge retention layer is provided on the information recording layer. 3. An information recording layer which is a resin body in which a liquid crystal phase is dispersed and fixed, and which is selected so that the optical refractive index of the resin body and the optical refractive index in a state where the liquid crystal material is oriented by an electric field almost match. An information recording medium having a photoconductive layer provided on an electrode layer and a photoreceptor having a photoconductive layer provided on the electrode layer are placed facing each other, and a voltage is applied between both electrodes while exposing the photoreceptor or information recording medium to light. An electrostatic information recording and reproducing method characterized by recording electrostatic information, recording and storing the electrostatic information as visible information, and reproducing it at an arbitrary time. 4. Electrostatic information recording according to claim 3, characterized in that before electrostatic information is recorded on the information recording medium, the information recording medium is heated to a temperature above room temperature and below the isotropic phase transition temperature of the liquid crystal substance. How to play. 5. The electrostatic information recording and reproducing method according to claim 3, wherein the visible information is reproduced by transmitted light or reflected light.