JPH02134615A - Color image display device - Google Patents

Abstract

PURPOSE:To form a color original picture directly from the output signal from a magnetic reader, etc., by using a high-molecular cholesteric liquid crystal member alone or using the liquid crystal member and a thermosensitive member which is reversibly changed in transparency by temp. and further a coloring member in combination as a recording material. CONSTITUTION:The laminar liquid crystal member L having the high-molecular cholesteric liquid crystal material is used independently or the combination of the liquid crystal member and the thermosensitive member T which is reversibly changed in transparency dependently upon temp. is used as the thermosensitive recording material 1. Means 2 for forming images by selective impression of heat, a means 3 for erasing the images by impression of heat and the coloring member 4 to be used in combination with the above-mentioned thermosensitive recording member 1 are provided. The coloration state is formed without impairing the reversibility of the reversible thermosensitive recording material in this way and the respective functions of writing the color images onto the film which allow the formation of >=2 colors of the displayed images and erasing thereof are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image display device, particularly a layered liquid crystal member having a polymeric cholesteric liquid crystal material and/or a layered thermosensitive member whose transparency changes reversibly depending on temperature. The present invention relates to a color image display device used as a recording material.

Traditionally, CRT displays have been widely used as image display devices for personal computers, word processors, etc., but they suffer from problems such as being large, expensive, and requiring a lot of energy to display images. There were drawbacks.

Furthermore, although liquid crystal displays have recently attracted attention as display devices with low power consumption, they have low image contrast and are difficult to increase in size.

To solve these drawbacks, a display device using a thermoreversible recording material whose transparency changes reversibly with heat has been proposed (see Japanese Patent Application Laid-Open No. 57-92370, etc.). Since the recording material utilizes only the change in transparency between transparent and cloudy, it has not been possible to form a color image.

Purpose The present invention provides a method for writing and erasing color images on a recording material, which enables the formation of a colored state and the formation of display images of two or more colors without impairing the reversibility of conventional reversible thermosensitive recording materials. An object of the present invention is to provide a color image display device having various functions.

Structure The color image display device of the present invention uses, as a heat-sensitive recording material,
(a) A layered liquid crystal member having a polymeric cholesteric liquid crystal substance alone, or (b) a combination of the liquid crystal member and a heat-sensitive member whose transparency changes reversibly depending on temperature, and (i) selects heat. means for forming an image by applying
It is characterized by comprising: ii) means for erasing the image by applying heat to the entire surface or partially; and (iii) a coloring member used in combination with the heat-sensitive recording material.

The present invention provides (a) a layered liquid crystal member having a polymeric cholesteric liquid crystal substance, or (b) a heat-sensitive recording material.
It is characterized by using a combination of the liquid crystal member and a heat-sensitive member whose transparency changes reversibly depending on temperature, and further characterized by using the heat-sensitive recording material in combination with a colored member. .

By providing a liquid crystal member, when printing is performed, the liquid crystal changes color depending on the print recording temperature, and a clear color recorded image is obtained, and accordingly, the displayed image also becomes a clear colored image.

The display device of the present invention, like the conventional one, includes an optical reading device,
In addition to the function of creating an original drawing by directly forming an image from the output signal of a facsimile, personal computer, magnetic reader, etc., it also has the function of erasing and reproducing this image.

In addition, this image is maintained without applying any energy.The erase and regenerate function of the 0 image is due to the property that the color changes depending on the temperature of the polymeric cholesteric liquid crystal, and the transparency changes reversibly depending on the temperature of the heat-sensitive member. It takes advantage of this characteristic.

Here, (i) means for selectively applying heat to form an image include means such as a thermal head and electrical heating.

(ii) Means for erasing an image by applying heat entirely or partially include means for blowing hot air, means for pressing heated rollers, means for pressing with a hot plate,
Examples include means using a thermal head.

Furthermore, (iii) the color of the colored member used in combination with the heat-sensitive recording material is preferably as dark as possible, such as black, dark green, dark red, dark blue, etc. Colored parts include films, glass, metals coated with inks containing dyes and pigments of the above colors, films,
Examples include those in which dyes and pigments of the above colors are kneaded into glass.

Various forms of the combination of heat-sensitive recording material and colorant used in the present invention are shown in FIGS. 2(a) to 3(d) and 3 of the accompanying drawings.
As shown in Figures (,) to (g), B is a support, B' is a colored support, T is a heat-sensitive layer, L is a liquid crystal layer, and C is a colored layer.

FIGS. 2(a) to (d) show examples in which only a layered liquid crystal material containing a polymeric cholesteric liquid crystal substance is used as a heat-sensitive recording material, and FIGS. This is an example in which a combination of a layered heat-sensitive member T made of an organic low-molecular substance dispersed in a resin base material and whose transparency changes reversibly depending on the temperature is used as a heat-sensitive recording material.

That is, Fig. 2(a) shows a layered liquid crystal member L on one side of the support B, and a layered liquid crystal member L on the opposite side. The coloring member C is provided; FIG. 2(c) shows a structure in which the layered liquid crystal member and the coloring member C are provided on separate supports, and each is made as a separate body and used by stacking them one on top of the other. FIG. 2(d) shows a colored support B' in which the support itself is colored, and a liquid crystal member is provided thereon.

Further, FIG. 3(a) shows a structure in which a colored member C1, a layered heat-sensitive member T, and a layered liquid crystal member are sequentially laminated on a support B; FIG. 3(b) shows the structure shown in FIG. 3(a) above. 3(c) shows a structure in which the layered heat-sensitive member T and the layered liquid crystal member are replaced; FIG. Figure 3(d) shows a layered heat-sensitive member T and a layered liquid crystal member on both sides of another support B, with the coloring member C being separate; FIG. 3(e) shows the layered liquid crystal member as a separate member; FIG. 3(f) shows the layered heat-sensitive member T as a separate member; and FIG. 3(g) shows the colored member. C1 The layered liquid crystal member and the layered heat-sensitive member T are shown as separate bodies.

The cases shown in FIGS. 3(d), (e), (f), and (g) are cases in which the single-layer liquid crystal member and the layered heat-sensitive member T are heated separately by separate heating means to form an image. This is an example used in

What is shown in the above-mentioned drawings is one in which the layered liquid crystal member and the layered heat-sensitive member T are provided as separate layers.
By using a polymeric liquid crystal material instead of resin as the matrix of the layered heat-sensitive member T, both functions may be included in a single layer.

These structures may be provided with a protective layer on the outermost side, if necessary.

These heat-sensitive recording materials can take various forms such as a sheet, an endless film, or a combination thereof.

Support B is a transparent or colored material, such as a plastic film, for example a polyester film (Mylar),
Known materials such as glass plates and metal plates can be used. The thickness of the support B is preferably about 10 to 300 μm. In addition, when using electrical heating as the heating means, it is necessary to adjust the resistance value of the support by adding additives or the like.

The protective layer is preferably made of a transparent material, such as silicone rubber, silicone resin (see JP-A-63-221087), polysiloxane graft polymer (see JP-A-63-221087),
No. 152550), ultraviolet curing resin (patent application No. 152-31)
A transparent film such as No. 0969) can be used, and its thickness is preferably 10 μm or less.

The thickness of the heat sensitive layer T is 1 to 30 μm, preferably 10 to 3 μm.
Approximately 0 μm is good. When the thickness is 1 μm or less, the white turbidity decreases and the contrast decreases, and when the thickness is 30 μm or more, the thermal sensitivity decreases. The materials constituting the heat-sensitive layer will be detailed below.

The thickness of the liquid crystal layer may be approximately the same as that of the heat-sensitive layer T.

The layered liquid crystal member used in the present invention can change color to various colors depending on temperature.

After heating, the color remains fixed even when the temperature is returned to room temperature.

At least one kind of liquid crystal substance is used in this layered liquid crystal member, and the liquid crystal substance is preferably a thermotropic polymer cholesteric liquid crystal derivative. The color change of liquid crystal materials is due to the property that the helical pitch of polymeric cholesteric liquid crystal changes depending on the temperature, selectively reflecting or transmitting light of a specific wavelength corresponding to the pitch length, and circular dichroism. This is because the helical pitch is fixed by heating to a corresponding temperature and then rapidly cooling, and the coloring state due to reflection or transmission of a specific wavelength can also be stabilized.

The type of coloring and coloring temperature can be arbitrarily changed depending on the selected thermotropic polymer cholesteric liquid crystal.

The recording principle of the recording material used in the present invention utilizes changes in the transparency of the heat-sensitive MT and changes in color of the liquid crystal layer due to temperature, and this will be explained with reference to FIG. In FIG. 1, the heat-sensitive layer T is in a cloudy, opaque state at a room temperature of, for example, T0 or higher.

When heated to a temperature between T1 and T2, it becomes transparent, and even if it is returned to room temperature below T, it remains transparent and almost colorless. If this completely transparent material is further partially heated to a temperature higher than T1 using a thermal head, etc., and then rapidly cooled to room temperature lower than T0, only the heated portion will remain in the initial opaque state without becoming transparent. It becomes an opaque area according to . Then, by creating a transparent image using this heat-sensitive layer with the cloudy part as a background, and coloring the liquid crystal layer at a portion corresponding to the transparent image, a clear color image with the cloudy part as the background can be obtained. The recording material of the present invention comprises 1
A color that develops two or more colors because it reflects light of a specific wavelength corresponding to the a-rotational pitch of the thermotropic polymer liquid crystal that changes depending on the temperature by heating to two or more different temperatures of three or more. The formation of different images is also possible.

As a recording material, a liquid crystal material that can be colored in various colors by changing the heating temperature may be used alone, but by combining a liquid crystal material and a heat-sensitive material, a colored image with significantly improved contrast can be formed. Furthermore, it is possible to add a border to the colored image, and it is possible to form a display body that is easier to see than just the colored image on the liquid crystal member. Furthermore, by using these heat-sensitive recording materials in combination with a colored member, a color image display body with significantly improved contrast against the background of the colored member can be obtained.

The transparent part of the layered heat-sensitive material appears transparent because the organic low-molecular substance dispersed in the resin base material in this part is composed of large crystal particles, so light incident from one side is scattered. This is thought to be because the light passes through to the other side without any interference.

The reason why the opaque area appears white is because the organic low-molecular substance dispersed in the resin base material in this area is composed of polycrystalline particles, which are aggregates of microcrystals, and the crystal axes of the individual crystals are oriented in various directions. This is thought to be because light incident from one side is refracted and scattered many times at the interface of each crystal.

Recording and erasing on the heat-sensitive recording material as described above can be repeated at least 10 times.

The polymeric liquid crystal material used in the liquid crystal layer is preferably a thermotropic polymeric cholesteric liquid crystal derivative. In either case, it is necessary that the main chain or bent chain contains an optically active unit, and the mesogenic group having the optically active unit is
methacrylic acid ester, etc.) with or without a spacer, or poly[oxy(methylsilylene), which is obtained by bonding a reactive mesogen monomer to a polymer backbone chain. )] with a vinyl-substituted mesogen monomer added to the side chain of the 5i-H bond, or with a low-molecular-weight mesogen or cholesterol derivative added to the functional group, or with an esterification reaction to polypeptide to form a cholesteric liquid crystal, etc. Cholesteryl-ω-(4-methacryloyloxyphenylalkanoate), siloxane derivatives with cholesterol derivatives and nematic liquid crystal molecules added, siloxane derivatives or copolymers with nematic liquid crystal molecules added, benzyl ester of polyglutamic acid. A copolymer of dodecyl ester and dodecyl ester is known as a typical thermotropic polymer cholesteric liquid crystal.

(The following is a blank space) Specific examples of polymeric liquid crystal substances used in the present invention are shown below.

i) Main chain type liquid crystal polymer Polyester, polyesteramide having the following structure,
Homopolymer or copolymer such as polycarbonate or polyether, etc.;
-%CH-CH20)-n.

CH3 A: M knee + CH, -) -n, +CH, CH2O+n, -+
CH-C120+n-◎-◎-R, -0-◎-◎-R,
-@-COO-◎-R, -0-◎-COO-◎-R.

Xl.

X2 ni -Coo-, -CONH-, -0CO-, -0-, etc.

ii) Side-chain type liquid crystal polymer A homopolymer or copolymer of vinyl polymer, siloxane polymer, etc. having the following structure 〇-◎-◎-0CO
-◎-R9-■-0CO-■, -〇-R9-〇-◎-o
co-◎-@-R1-cH,-goI(-R,-goH-R
,=N-koH-◎CH□ CH3CH.

Cholesterol derivative (the umbrella represents an optically active carbon atom, R represents a substituent such as alkyl, alkoxy, halogen, nitro, cyano, branched alkyl, substituted alkyl, hydrogen atom, etc.) iii) Rigid main chain type liquid crystal polymer In addition to polypeptides having the following structures, homopolymers or copolymers of polyisocyanates and cellulose derivatives: Next, a specific structural example of a preferred cholesteric liquid crystal polymer used in the present invention will be shown.

+0-■-Coo-@-0CO+C)l,)2-koH-
CH□-C+.

OOR 0OR COOR' (R and R' represent alkyl, alkoxyalkyl, nalalkyl, aryl groups, etc.) Alternatively, the following mixed liquid crystal polymer of rigid main chain type and side chain type: R , , , , ,,,(-0-■-C=CH-◎-Co-+C
H2) 4-Co-)-, -λ.

C0OR0R (R represents an alkyl group, etc.) CH.

+CH, -C-)- cOO-@+CI(,)n-COOC27H,sCHl (-CH,-C+X C.I.

0. ,,,,,,,,,,,,(-CH,-C→-1-
S+NH-C)l-Co+x, -, ---, ---
-+NH-CH-CO+1-xCH.

(C12-C+x, , , , , , , , , .

coo(C)I2)s-◎-COO-@-■-0CR.

CH.

, , , , , *-%C)! ! -C+1-xCOO(
C) l, ), -0-◎-COO-◎-CH=N- and H-
◎CH.

CH.

+5i-0+ (CH2)m-0-◎-coo-◎-cos-koH-+
CH2)3-CH3°CH.

CH, CH.

+5i-0)x , , , , , , , , , , , ,
,,+5L-0+i-X+1 (CH,)n+-0-◎-COO-◎-OCH, (CH
2), -COOC,, H4s.

-+NH-CI(-CO+ CH, CH, -COOCH2-◎-0R(R: -C
)13. -C-Htt, -CxJlzs*-C1sHi
3. -':<2H4ri-CH,CH,-COO(CH,
), H to CH3COO.

In the heat-sensitive layer T, the organic low-molecular substance exists in a dispersed state as fine particles in the resin base material. In order to have the functions of both the heat-sensitive layer T and the liquid crystal layer in a single layer, a polymer liquid crystal substance is used instead of the resin base material in the heat-sensitive layer, and an organic low-molecular substance is added to the polymer liquid crystal substance. It is better to disperse the

On the other hand, the organic low-molecular substance may be selected as appropriate depending on the temperature T and ~T in Figure 1, and a material whose melting point or freezing point corresponds to the temperature T2 to T3 may be selected depending on the purpose. 1 For example, melting point 30-200°C, especially 50-150°C
Examples of such organic low-molecular substances, which preferably have a temperature of approximately 0.degree. Examples of such organic low molecular weight substances include alkanols; alkanediols; halogenalkanols or halogenalkanediols; alkylamines; alkanes; alkenes; alkynes; halogenalkanes; halogenalkenes, halogenalkynes; cycloalkanes; cycloalkenes; cycloalkynes ; Saturated or unsaturated mono- or dicarboxylic acids or their esters, amides, or ammonium salts; Saturated or unsaturated halogenated fatty acids or their esters, amides, or ammonium salts;
Allylcarboxylic acids or their esters, amides or ammonium salts; halogen allylcarboxylic acids or their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids or their esters;
Examples include amines or ammonium salts; carboxylic acid esters of thioalcohols. These can be used alone or in combination
Used as a mixture of more than one species. The carbon number of these compounds is 10 to 60. Preferably 10 to 38, particularly preferably 10 to 30. The alcohol group moiety in the ester may be saturated or unsaturated, and may be halogen-substituted. In any case, it is an organic low molecular substance. contains at least one of oxygen, nitrogen, sulfur and halogen in the molecule, such as -○H9COOH, -CONH, -GOOR, -NH
--NH,, -5-, -3-8-, -〇-, a compound containing halogen, etc. is preferred.

More specifically, these compounds include higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, arachidic acid, and oleic acid; methyl stearate, and tetradecyl stearate. , esters of higher fatty acids such as octadecyl stearate, octadecyl laurate, tetradecyl palmitate, tocosyl behenate; C1GI+,
, -〇-C1,H,,,C1&H22-S-C1,H,
.

C18H3'l-3-C1゜H,, C1,H,, -5
-C1□HzgC1J3s-3-C1Jzs, Cx*
Hzs-5-5-CxzHzsCH2-CH, -Coo
(CH2), -CH-CH, -CH.

CH.

There are ethers and thioethers such as

The resin base material used for the heat-sensitive layer is a material that forms a film or sheet in which a low-molecular-weight organic substance is uniformly dispersed and holds, and also influences the transparency at maximum transparency. For this reason, the resin base material is preferably a resin with good transparency, mechanical stability, and good film-forming properties. Examples of such resins include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer.
Vinyl acetate - vinyl alcohol copolymer, vinyl chloride -
Vinyl chloride copolymers such as vinyl acetate-maleic acid copolymers and vinyl chloride acrylate copolymers; polyvinylidene chloride.

Vinylidene chloride copolymers such as vinylidene chloride-vinyl chloride copolymers and vinylidene chloride-acrylonitrile copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylate-methacrylate copolymers, silicone resins, and the like. These may be used alone or in combination of two or more.

The ratio of the organic low-molecular substance to the resin base material in the heat-sensitive layer is preferably about 1:0.5 to 1:16 by weight, and about 1:1 to 1:1.
A ratio of 1:3 is more preferable. If the ratio of the resin base material is less than this, it will be difficult to form a film that retains the organic low molecular weight substance in the resin base material. On the other hand, if the ratio is higher than this, the organic low molecular weight substance Since the amount of is small, it is difficult to make it opaque.

As a method for forming a heat-sensitive MT.

(b) A method in which both the organic low-molecular substance and the resin base material are dissolved in a solvent, and when the solvent is evaporated, the organic low-molecular substance is precipitated as fine particles; (b) A method that uses a solvent that dissolves only the resin base material. or (c) heating and melting both the organic low-molecular substance and the resin base material without using a solvent. , a method of mixing and then cooling to form a heat-sensitive layer sheet.

As the solvent for forming the heat-sensitive layer, various solvents can be used depending on the type of organic low-molecular substance and high-molecular liquid crystal substance.1For example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene. , benzene, and other organic solvents.

liquid crystal! JL can be arbitrarily formed by dissolving a thermotropic polymeric cholesteric liquid crystal substance in the same solvent as used for forming the heat-sensitive layer T, and using a conventionally known coating method such as a casting method.

Hereinafter, the present invention will be explained in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 An example of a color image display device of the present invention is shown in FIG. 1
1 shows a recording material made of an endless film, and a black colored member 4 is arranged on the back side. Further, 2 is a thermal head for image formation, which is a means for forming an image by selectively applying heat, and 3 is a heat roller, which is a means for erasing an image by heating. These heating means 2 and 3 are arranged close to or in contact with the heat-sensitive recording material 1. Note that 5 is a drive circuit for the thermal head 2, and 6 is an optical reading device.

In such a display device, for example, an original drawing or manuscript (
The image (not shown) is read by an optical reader 6 placed at a remote location, and photoelectrically converted into an electrical signal. This electric signal drives the thermal head 2 by the thermal head drive circuit 5, and brings it into contact with the recording material 1, which is entirely transparent, and partially at 122°C and 128°C, respectively.
When heated to 140° C. and 140° C., the liquid crystal substance in recording material 1 changed color, and clear color images of purple, green, and red against the black background of the colored member were obtained.

The entire used image is heated to 110℃ by heating roller 3.
The material is erased by heating it to the original transparent recording material, making it reusable.

Example 2 Instead of the recording material consisting only of the layered liquid crystal member used in Example 1, a recording material combining a layered polymeric cholesteric liquid crystal member and a layered heat-sensitive member as shown in FIG. 3(c) was used. . When this recording material 1 was heated in advance at 110° C. using the same display device as used in Example 1, the heat-sensitive member became cloudy and the liquid crystal member became transparent.

When this was heated with the thermal head 2 in the same manner as in Example 1, the heated liquid crystal member changed color in the same manner as in Example 1.
The heat-sensitive member became transparent. A clear color image with a white background was obtained on the display surface of this display device.

The used image is erased by heating the entire body to 110° C. with the heating roller 3 as in Example 1, and the liquid crystal member becomes transparent again and the heat-sensitive member becomes cloudy and returns to the original recording material, making it possible to reuse it. It became a situation.

According to the above embodiments, various reversible thermosensitive display bodies as shown in FIGS. 2(a) to 3(d) and 3(a) to (g) are used, and a plurality of thermal heads are connected. It is within the scope of the present invention to easily modify the display format in various ways.

Effects As described above, the display device of the present invention uses a polymeric cholesteric liquid crystal member alone or a combination of the liquid crystal member and a heat-sensitive member whose transparency changes reversibly depending on temperature as a recording material, and further includes: By using the recording material and coloring member in combination, in addition to the original image display function, it is possible to create color originals directly from output signals from optical reading devices, facsimiles, personal computers, magnetic reading devices, etc. In addition, the image can be maintained without applying any energy, the displayed image has much improved contrast than in the conventional case, and used originals can be erased and reused.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the recording and erasing principle of the reversible thermosensitive recording material of the present invention. FIGS. 2(a) to 3(d) and 3(a) to 3(g) are explanatory diagrams showing various configuration examples of the reversible thermosensitive display body used in the color image display device of the present invention. FIG. 4 is an explanatory diagram of the color image display device of the present invention. 100. Recording materials 218. Thermal head 3016 Image erasing heating means 4108 Coloring member 500. Thermal head drive circuit 6000 image reading device B11. Support B' 100 Colored support T81. Heat sensitive layer 06. Liquid crystal layer C601 colored layer patent applicant stock

Claims (1)

[Claims] 1. A layered liquid crystal member having a polymeric cholesteric liquid crystal substance is used as a heat-sensitive recording material, (i) means for forming an image by selectively applying heat, (ii)
1.) A color image display device comprising: a means for erasing an image by applying heat entirely or partially; and (iii) a coloring member used in combination with the heat-sensitive recording material. 2. A combination of a liquid crystal member containing a polymer cholesteric liquid crystal substance and a heat-sensitive member whose transparency changes reversibly depending on the temperature is used as a heat-sensitive recording material, and (i) heat is selectively applied to form an image. (ii) means for entirely or partially applying heat to erase the image; and (iii)
) A color image display device comprising a coloring member used in combination with the heat-sensitive recording material.