JPS61198123A - Image recording device - Google Patents

Abstract

PURPOSE:To easily save and rewrite image information by cooling a liquid- crystal element for a time long enough to orient the liquid crystal in the liquid- crystal element vertically in orientation processing. CONSTITUTION:Surfaces of a glass substrate 1 of 50mum in thickness and a substrate 3 of 1mm are oriented vertically, the upper and lower substrates are spaced at an internal of 20mum, and liquid crystal 2 which has a smectic A phase at room temperatures and an orienting material are charged between those two substrates to obtain the liquid-crystal element 4. In a heating process, the liquid-crystal 4 is sent by a belt 6 and heated into an isotropic liquid phase by a power source 12 and a resistance line or a heating lamp 5. In a cooling process, the liquid-crystal element 4 is conveyed by a belt 8 under a heater 7 which has a temperature gradient and then the liquid-crystal layer is cooled gradually to have phase transition in the order of the isotropic liquid phase, nematic phase, and smectic phase. The image surface of the liquid-crystal ele ment 4 becomes transparent through said two processes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording device, and particularly to a simple image recording device using a rewritable medium.

In recent years, there has been an increase in demand for the use of writable media for image recording, but the conventional technology had several problems in practical use.1 For example, display devices are often used to make offices paperless. However, with display devices such as CRTs, it is difficult to display texts in high definition, and there is a problem in that images cannot be stored as images for a long period of time. Furthermore, since hard copy images produced by so-called printers cannot be rewritten, there is a problem in that the amount of paper used increases. On the other hand, although cash cards and credit cards are widely used, there is also a demand for recording amounts and other information on these cards. Although it is possible to meet these demands by using a flat display device, for example, the device has disadvantages such as requiring a power source and having a complicated structure.

The present invention was made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a rewritable medium and an image recording device for reading and rewriting images.

[F-stage for solving the problem] The present invention makes the surface of the liquid crystal element transparent by heating the entire liquid crystal element and cooling the liquid crystal element which is sandwiched between substrates, and which exhibits a thermo-optical effect. Next, image information is written by locally heating means, and in particular, in the t stage where the liquid crystal element is vertically aligned and cooled, the liquid crystal in the liquid crystal element is vertically aligned according to the alignment process. This method is characterized by cooling with sufficient time.

The liquid crystal used in the present invention is preferably a mixed liquid crystal of nematic liquid crystal and cholesteric liquid crystal, or a smectic liquid crystal having a nematic phase.

[Sakukawa] Explains the principle of operation when using a smectic liquid crystal as a liquid crystal that exhibits a thermo-optic effect.

When the liquid crystal layer is heated, the orientation state of the liquid crystal layer t becomes an isotropic liquid phase state. Thereafter, during the cooling process, the liquid crystal layer changes from an isotropic liquid phase state to a nematic phase and a smectic A phase, and its alignment state is stabilized in the smectic A phase.

If the substrates sandwiching the liquid crystal layer are made of soil that has been vertically aligned in advance, and the state inside the liquid crystal layer passes through the nematic phase, if it is cooled for a sufficient period of time, the liquid crystal layer will gradually cool down, and the substrate wall surface will Due to the alignment effect, the molecules within the liquid crystal layer become vertically aligned, resulting in an optically transparent state. On the other hand, if the liquid crystal layer is rapidly cooled, the molecules within the liquid crystal layer are rapidly cooled while remaining in a random state of an isotropic liquid phase, resulting in an optically cloudy state.

[Embodiment 1] An embodiment of the image recording method of the present invention will be described below with reference to FIGS. 1 and 2.

Figure 1 is a block diagram showing one embodiment of a liquid crystal element used in the present invention. In Figure 1, 1 and 3 are glass plate substrates. In this embodiment, the thickness of the substrate 1 is 50Bm, and the thickness of the substrate 3 is The thickness of the two substrates was 1 mm, each inner surface was vertically aligned, and the space thickness between the upper and lower substrates was 20 $L-. Between these two substrates, a liquid crystal 2 (8
Company 08, product name: rs-s J) and F as an alignment material.
Liquid crystal element 4 by enclosing J-150 (Dainippon Printing III)
I got it.

A method of recording an image on this liquid crystal element 4 will be explained next. Second
Each recording process on the liquid crystal element 4 is shown in FIGS.

FIG. 2(a) is a diagram showing the heating process, in which the liquid crystal element 4 is sent in the direction of the arrow by a belt 6, and the liquid crystal layer f4 is heated to an isotropic liquid phase by a power source 12 and a resistance wire or heating lamp 5. do.

FIG. 2(b) is a diagram showing the cooling process. When the liquid crystal element 4 is conveyed by the belt 8 in the direction of the arrow under the heater 7 which has a temperature gradient, the liquid crystal layer C is slowly cooled from an isotropic liquid phase to a nematic phase to a smectic phase. Here, it is desirable that the heater 7 has a temperature gradient from a temperature higher than the isotropic phase-nematic phase transition temperature of the liquid crystal layer to a temperature near room temperature in accordance with the traveling direction of the liquid crystal element.
,). The material for the belt 8 is preferably a heat insulating material, and in this embodiment, a rubber belt is used.

By going through these two processes, the liquid crystal element 4
The image display surface becomes transparent.

FIG. 2(c) is a diagram showing the thermal writing process. At 21A (c), the liquid crystal element 4 that has come into contact with the thermal head 9 is sent in the direction of the arrow by the platen roller 10. At this time, the thermal head 9 controlled by the signal source 11 locally generates heat in accordance with the image information, and the liquid E'a12 is heated from the smectic phase to the isotropic liquid phase in accordance with this heat generation number. However, in this process, since no electric field is applied, the liquid crystal 2 is exposed to the thermal head 9.
After passing through, the breath cools and becomes cloudy. That is,
The selected surface portion of the liquid crystal element 4 is exposed to a thermal head 9.
The area is locally heated and becomes cloudy, creating an optical density difference between the area and the unheated area, and one image information is recorded.

In this embodiment, the heater 7 has a temperature gradient of 230°C to 150"O, and the belt 8 is set so that the liquid crystal element 4 passes under the heater 7 in less than 1 minute, preferably about 1 to 3 seconds. When I adjusted the moving speed and let it pass, the liquid crystal element 4
After the display surface became transparent, pulsed heat application of about 2 J/CM2 was performed using the thermal head 9, and as a result, a good white cloudy image could be obtained.

The cloudy image thus obtained had good memory even at room temperature, and the memory did not change even with changes in temperature or body temperature when handled by hand.

In the above embodiment, if the heat from the thermal head 9 is diffused by the substrate 1 on one side of the liquid crystal element 4, the image will be distorted, so it is desirable that the thickness of the substrate 1 on one side be several hundred lure or less.

[Application example] By mixing a dye into the liquid crystal 2, it was possible to obtain not only two types of display, "transparent" and "cloudy", but also color recording. Furthermore, as another application example, a flexible recording medium could be obtained by using a substrate such as PET (polyethylene terephthalate) instead of a glass substrate.

[Effects of the Invention] In the present invention, a liquid crystal exhibiting a thermo-optic effect is used as an image information recording medium, and an image is recorded by the thermo-optic effect, which saves image information more easily than conventional methods. , rewriting can be done easily.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of a liquid crystal element used in the present invention, and FIGS. 2(a) to (C) are explanatory diagrams of each recording process in an embodiment of the image recording method according to the present invention. be. 1.3...Rim plate, 2...Liquid crystal, 4...Liquid crystal element. 5... Heat lamp, 6, 8... Belt, 7... Heater +, 9... 4j-full head, 10... Platen roller, 11... Signal source, 12... Power supply.

Claims (1)

[Scope of Claims] 1) A liquid crystal element comprising a liquid crystal exhibiting a thermo-optic effect sandwiched between upper and lower substrates, and a means for heating the liquid crystal element from the outside, a means for cooling the liquid crystal element, and a means for locally heating the liquid crystal element. An image recording apparatus characterized in that image information is recorded by sequentially applying these means to the liquid crystal element. 2) The image recording apparatus according to claim 1, wherein the means for locally heating is a thermal head. 3) The liquid crystal element is subjected to vertical alignment treatment, and the cooling means is characterized in that the cooling is performed for a sufficient time for the liquid crystal in the liquid crystal element to be vertically aligned according to the alignment treatment. An image recording apparatus according to claim 1.