JPS63309930A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain display whose display definition is not damaged even when a temperature changes remarkably, by performing the integral wiring of a heat conductor <=50kOMEGA on at least the inner wall plane of a substrate on one side extending over the inside and the outside of a sealing member, and arranging a temperature sensor by adhering closely on the outside part of the sealing member. CONSTITUTION:In a cell structure body 100, a pair of substrates 101 and 101' consisting of glass plates or plastic plates are held with a spacer 104 keeping a prescribed interval, and in a liquid crystal device, the heat conductor 106 is arranged in the cell in a stripe shape, and the temperature sensor 107 is adhered closely and connected to the outside part of the sealing member 105. Furthermore, resin 108 with a low heat conductivity coating the temperature sensor 107 is coated. Also, the resistance of the heat conductor 106 is set at the resistance <=50kOMEGA generally, or at <=30kOMEGA preferably. In such a way, it is possible always to display a numeral or an image pattern, etc. at constant contrast, and to stabilize visual recognition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal device, and more particularly to a ferroelectric liquid crystal liquid crystal device with improved temperature compensation during driving.

[Prior art]

Conventionally, liquid crystal display elements are well known in which a scanning electrode group and a signal electrode group are configured in a matrix, and a liquid crystal compound is filled between the electrodes to form a large number of pixels to display images or information. . This liquid crystal display element has a characteristic that the response speed becomes slower as the temperature becomes lower. Furthermore, it has the property of transitioning from liquid crystal to liquid at temperatures above the liquid crystal transition point temperature. In order to use such a liquid crystal display element in a wide temperature range, a voltage control means is required to detect the temperature of the liquid crystal element and increase the drive voltage to a high voltage when the temperature is low, and to a low voltage when the temperature is high. Frequency control means have been used to vary the driving frequency depending on the temperature and temperature. In addition, measures have been taken to maintain the liquid crystal element at a predetermined temperature using a heater or fan.

However, because conventional temperature sensors are mounted on the glass substrate of the liquid crystal element, it cannot be said that they accurately detect the temperature of the liquid crystal material itself, and image quality may deteriorate if there is a large temperature change. There was a problem. In particular, in the case of liquid crystal devices using ferroelectric liquid crystals, the threshold characteristics of the ferroelectric liquid crystals vary greatly depending on temperature changes, and when the temperature changes rapidly, display unevenness appears due to poor switching. there were.

[Summary of the invention]

Therefore, an object of the present invention is to provide a liquid crystal device that can provide a display that does not deteriorate the display quality even when the temperature fluctuates greatly. The purpose is to provide a liquid crystal device using a ferroelectric liquid crystal.

That is, the present invention provides a liquid crystal device having a first substrate, a second substrate, a liquid crystal disposed between the first substrate and the second substrate, and a sealing member for sealing the liquid crystal. A liquid crystal display in which a thermal conductor of less than 50 Ω is integrally wired on the inner wall surface of at least one of the second substrates over the inside and outside of the sealing member, and a temperature sensor is placed in close contact with the outside of the sealing member. The device has features. [Detailed Description of Embodiments of the Invention] The present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show an embodiment of the liquid crystal device of the present invention. FIG. 1(A) is a plan view of a liquid crystal device of the present invention, and FIG. 1(B) is a cross-sectional view taken along line AA'.

In the cell structure 100 shown in FIG. 1, a pair of substrates 101 and 101' made of glass plates or plastic plates are held at a predetermined distance by spacers 104, and an adhesive is used to seal the pair of substrates. Furthermore, on the substrate 101, a plurality of transparent electrodes made of ITO (Indium thin 0x
ide) 102 (for example, an electrode group for applying a scanning voltage in a matrix electrode structure) is formed in a predetermined pattern such as a strip pattern, and the substrate 101'
An electrode group (for example, a signal voltage application electrode group in a matrix electrode structure) is formed on the transparent electrode 102 and a plurality of transparent electrodes 102' intersecting with each other. Further, crossed Nicol polarizing plates 109 and 109' are arranged on both sides of the cell structure 100.

In this liquid crystal device, a thermal conductor 106 is arranged in the cell in the form of a stripe, and a temperature sensor 107 is closely connected to the outer side of the sealing member 105 of the thermal conductor 106. Further, a resin 108 with low thermal conductivity (for example, an epoxy adhesive cured under predetermined curing conditions) is applied to cover the temperature sensor 107 .

The substrate 101' provided with such a transparent electrode 102' includes, for example, silicon oxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide,
Inorganic insulating materials such as cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene , 0 cellulose resin, melamine resin,
The alignment control film 110 may be formed using an organic insulating material such as area resin or acrylic resin.

This orientation control film 110 is obtained by forming a film of an inorganic insulating material or an organic insulating material as described above, and then rubbing the surface of the film in one direction with velvet, cloth, or paper.

The resistance of the thermal conductor 106 used in the present invention is generally 50K.
It can be set to Ω or less, preferably 30 Ω or less. Particularly, when indium tin oxide (I To) similar to the transparent electrode 102 (or 102') is used as the thermal conductor 106 (i.e., a sheet of the thermal conductor 106 and the transparent electrode 102 (or 102') The resistance was approximately the same), the film thickness was 100λ to 10μ, preferably about 500 to 5000, the length was several meters or less,
Preferably, the width is 50 cm or less, and the width is 50 μ to imm.
More preferably, the thickness is about 100μ to 500μ. At this time, the sheet resistance of the thermal conductor 106 is preferably set to 15'Ω/hole or less, preferably 10<3 >Ω/hole or less. In addition, the sheet resistance is ASTM D-257 (A
n American National 5t
and andard). The width of the thermal conductor 106 is preferably about 1.5 to 5 times wider than the transparent electrode 102 (or 102').

Further, in the present invention, the thermal conductor 106 can be formed of metal (for example, silver, copper, aluminum, chromium, etc.) or an alloy thereof, and in this case, the thermal conductor 106
The resistance can be set to less than 20Ω, preferably less than IOKΩ. In addition, in the present invention, metal oxides such as SnO2, MgO, ZnO, AI, 03, etc. can be used as the thermal conductor.

In the present invention, a resistance temperature detector (RTD) is mounted as a temperature sensor 10 on the above-mentioned thermal conductor 106 on the outside of the sealing member 105.
Chromel alumel thermocouple (JIS Type K, coated with JIS Pt1OO, manufactured by Rika Kogyo Co., Ltd.)
R: manufactured by Rika Kogyo Co., Ltd.) was brought into close contact. Further, in the present invention, an epoxy adhesive cured by heat is used as the resin 108 having low thermal conductivity, and the temperature sensor 10 is covered with this. In addition, it is also possible to use insulating polymer materials such as polystyrene, polyester, nylon, polyacrylate, etc. as the resin with low thermal conductivity.

Further, in the present invention, it is also possible to provide the above-described thermal conductor 106 and temperature sensor 107 on both side substrates.

The output from the temperature sensor 10 described above is input to the temperature compensation circuit 202 shown in FIG.
The driving voltage and driving frequency of 01 can be modulated according to the temperature.

FIG. 2 shows a block diagram of the liquid crystal device of the present invention.

The panel 201 in FIG. 2 includes a scanning line 202 and a data line 2.
03 are wired to cross each other, and a ferroelectric liquid crystal 13 is arranged between the scanning line 202 and the data line 203 at the intersection. In addition, in FIG. 2, 204 is a scanning circuit;
05 is a scanning side drive circuit, 206 is a signal side drive voltage generation circuit, 207 is a line memory, and 208 is a shift register. Furthermore, the device shown in FIG. 2 is provided with a voltage control circuit 209, a frequency control circuit 210, and a temperature control circuit 211 that control the drive voltage and drive frequency based on the temperature measurement data input to the temperature compensation circuit 202. .

The ferroelectric liquid crystal 13 used in the present invention is most preferably a chiral smectic liquid crystal having ferroelectricity, among which chiral smectic C phase (SmC*) or H phase (
SmH*) liquid crystal is suitable. This ferroelectric liquid crystal is described in “Le Journal de Physic”.
letter”) Volume 36 (L-69), 1975 “
Ferroelectric Liquid Crystals J
(rFerrOelectric Liquid
“Crystals”); “Applied Physics Letters”
Letters”) Volume 36 (1x-1, 1980 “Submicron Second Bistiple Electro-Optic Switching in Liquid Crystal” (rsubmicro 5econd B
15table Electrooptic Sw
Itching in Liquid Crys
taISJ); “Solid State Physics 16 (141) 198
1 "Liquid Crystal" and the like, and the ferroelectric liquid crystal disclosed in these can be used in the present invention.

More specifically, examples of ferroelectric liquid crystal compounds used in the present invention include decyloxybenzylidene-P'-amino-2-methylbutylcinnamate CD, OBAMB
C), hexyloxybenzylidene-P'-amino-2
-Chloropropyl cinnamate (HOBACPC) and 4-o-(2-methyl)-butyl resorcylide”J
In addition to +-4'-octylaniline (MBRA8), etc., U.S. Patent No. 4,589,996, U.S. Patent No. 4
, 576.732, U.S. Patent No. 4,592,85
No. 8, U.S. Patent No. 4,596,667, U.S. Patent No. 4613209, U.S. Patent No. 461460
Ferroelectric liquid crystals described in US Pat. No. 9, US Pat. No. 4,622,165, US Pat. No. 4,639,089, etc. can be used. In particular, in the present invention, the thickness of the chiral smectic liquid crystal is preferably set to such a value that the helical structure inherent in the chiral smectic liquid crystal disappears in the absence of an electric field. In addition, in the present invention, instead of such ferroelectric liquid crystal, TN liquid crystal or Japanese Patent Application Laid-open No. 58-16809
A cholesteric-nematic bistable liquid crystal disclosed in Publication No. 3 and the like can also be used.

As an example, let's take a temperature increase rate x('
The change in the contrast of the panel was measured when the contrast ratio was increased (e/m1n). The measurement results are shown in Figure 3. The vertical axis in Figure 3 is the contrast of the panel at 27℃ (C, R27℃)
It is a value obtained by normalizing the contrast (C, Rx) after one minute when the ambient temperature of the panel is raised at a certain rate of temperature increase with reference to , and the horizontal axis is the rate of temperature increase around the panel.

Experiments were conducted for cases in which the temperature sensor was placed in close contact with an ITO electrode and a glass substrate (Si20).

As is clear from Figure 3, the temperature sensor is connected to the glass substrate (
s i02), the temperature rise rate is large due to the low thermal conductivity of the glass substrate, and a difference occurs between the temperature on the glass substrate and the temperature of the liquid crystal material, causing the driving conditions to change. The camera could not be set to the optimum condition, resulting in poor contrast and image quality. However, when the temperature sensor according to the present invention is closely attached to an ITO electrode and covered with an adhesive with low thermal conductivity (Eboxy adhesive), the ITO electrode reflects the temperature inside the panel and also has low thermal conductivity. Since the temperature sensor is coated with a low-temperature adhesive, it is not affected by the outside temperature and can accurately detect the temperature inside the panel, so even if the temperature rises rapidly, the contrast does not deteriorate and the quality is always high. The image quality was maintained.

〔Effect of the invention〕

According to the present invention, since the thermal conductor for temperature detection with high thermal conductivity is spread inside the panel, the temperature of the liquid crystal material can be detected with high accuracy, and the temperature sensor can be used with adhesives with low thermal conductivity. Since it is coated with resin, it is not affected by the ambient temperature.By eliminating the drawbacks of conventional temperature detectors, numbers or image patterns can be displayed with a constant contrast. , there are advantages such as stabilization of visibility.

[Brief explanation of drawings]

FIG. 1(A) is a plan view of a liquid crystal device of the present invention, and FIG. 1(CB) is a sectional view taken along line AA'. - FIG. 2 is a block diagram of the ferroelectric liquid crystal device used in the present invention. FIG. 3 is a characteristic diagram showing the change in contrast when the temperature is increased from 27° C. at a certain temperature increase rate.

Claims (10)

[Claims] (1) In a liquid crystal device having a first substrate, a second substrate, a liquid crystal disposed between the first substrate and the second substrate, and a sealing member for sealing the liquid crystal, the first substrate and the second substrate facing each other are provided. A thermal conductor of 50KΩ or less is integrally wired on the inner wall surface of at least one of the substrates across the inside and outside of the sealing member, and a temperature sensor is disposed in close contact with the outside of the sealing member. liquid crystal device. (2) A liquid crystal device according to claim 1, wherein driving electrodes are wired to the first substrate and the second substrate, and sheet resistances of the driving electrodes and the thermal conductor are substantially the same. . (3) Both the driving electrode and the thermal conductor are indium-
3. The liquid crystal device according to claim 2, wherein the liquid crystal device is made of tin oxide (ITO). (4) The liquid crystal device according to claim 1, wherein the temperature sensor is coated with a resin having low thermal conductivity. (5) The liquid crystal device according to claim 4, wherein the resin is a hardened adhesive. (6) The liquid crystal device according to claim 1, wherein the thermal conductor is made of metal or an alloy thereof. (7) The liquid crystal device according to claim 1, wherein the thermal conductor is formed of a metal oxide. (8) The liquid crystal device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal. (9) The liquid crystal device according to claim 8, wherein the ferroelectric liquid crystal is a chiral smectic liquid crystal. (10) The liquid crystal device according to claim 9, wherein the film thickness of the chiral smectic liquid crystal is set to be thin enough to eliminate the helical structure inherent in the chiral smectic liquid crystal when no electric field is applied.