JPH0634945A - Liquid crystal display panel - Google Patents

Abstract

(57) [Summary] [Structure] The liquid crystal composition 1 is sandwiched between the substrates 2 and 3 provided with a self-temperature control function having at least one of electrical conductivity and heat conductivity on the back surface side of the liquid crystal display panel. In addition, the reflection plate or the support plate 5 is arranged, and the protection plate 4 having at least one of electric conductivity and heat conductivity is arranged on the surface side of the liquid crystal display panel. [Effect] The temperature of the liquid crystal display panel can be kept constant at a low cost without requiring complicated control.
As a result, excellent display performance can always be obtained regardless of the usage environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel capable of maintaining a constant temperature.

[0002]

2. Description of the Related Art A liquid crystal display panel is used in a usage environment (for example,
The display performance such as the response time changes significantly depending on the ambient temperature. In other words, when used in a relatively good environment such as the display section of a 0A device, there is no problem, but when used in the display section of an automobile or the display section of various instruments, the operating environment is bad. However, the display environment may have a large influence on the display performance.

Therefore, a technique for improving display performance such as response time has been proposed. Among them, as a technique corresponding to the driving condition side, there is a technique of detecting the temperature of the liquid crystal panel forming the display unit and performing so-called temperature compensation for adjusting the driving conditions such as the driving voltage and the frequency. However, this technique has a problem that the size of the device increases and the cost increases due to the addition of the compensation function.

As another technique, there is a technique for keeping the temperature of the liquid crystal display panel constant.
An example is shown in No. 27237. This JP-A-57
The liquid crystal display cell in No. 27237 has a structure in which transparent electrodes (conductive films) are formed on both surfaces of one or both substrates that constitute the liquid crystal display cell, and the transparent electrode formed on one surface is used for heat generation. ing.

[0005]

However, since ITO, NESA, etc., which are usually used as transparent electrodes, are expensive, both surfaces of a substrate constituting a liquid crystal display cell, as in JP-A-57-27237, are not used. If the transparent electrodes are formed on the transparent electrodes, a total of four transparent electrodes are required, which causes a problem that the liquid crystal display cell becomes very expensive.

The present invention has been made in view of the above-mentioned problems, and by arranging a sheet heating element having a self-temperature adjusting function on the back surface side of a liquid crystal display panel, inexpensive and complicated control is required. An object of the present invention is to provide a liquid crystal display panel that can maintain the temperature at a constant level.

[0007]

In order to achieve the above object, a liquid crystal display panel of the present invention has an electric conductivity and a heat transfer property on the back surface side of a liquid crystal display panel in which a liquid crystal composition is sandwiched between substrates with electrodes. The sheet heating element having at least one of the above is disposed, and the sheet heating element has a self-temperature adjusting function as required, and the sheet heating element includes a supporting plate, a reflecting plate, and a protective plate. It is also configured to be used as.

Next, a specific example of the present invention will be described with reference to FIG. In this specific example, the liquid crystal composition 1 is sandwiched between a pair of substrates 2 and 3 having electrodes, a protective plate 4 is arranged on the front surface side of the substrate, and a reflection plate or a support plate 5 is arranged on the rear surface side. It is as a configuration.

The liquid crystal composition may be a ferroelectric liquid crystal composition, a nematic liquid crystal composition or the like. Examples of the ferroelectric liquid crystal composition include a ferroelectric low-molecular liquid crystal, a ferroelectric polymer liquid crystal, and a mixture thereof. Examples of the ferroelectric low-molecular liquid crystal include, for example, a ferroelectric low-molecular liquid crystal of one or more kinds, and a ferroelectric low-molecular liquid crystal of one or more kinds and a mixture of other low-molecular liquid crystals. Examples thereof include low molecular liquid crystals. Examples of the ferroelectric polymer liquid crystal include, for example, one or two or more ferroelectric polymer liquid crystals, one or two or more ferroelectric low-molecular liquid crystals, and one or two or more ferroelectric polymers. Examples thereof include ferroelectric polymer liquid crystal composed of liquid crystal, ferroelectric polymer liquid crystal composed of one or more kinds of ferroelectric low molecular liquid crystal, and one or more kinds of other polymer liquid crystal. That is, as the ferroelectric polymer liquid crystal, a ferroelectric polymer liquid crystal (a homopolymer or a copolymer or a mixture thereof) in which the polymer molecule itself exhibits ferroelectric liquid crystal characteristics, a ferroelectric polymer liquid crystal and other Mixture of high molecular liquid crystal and / or ordinary polymer, mixture of ferroelectric high molecular liquid crystal and ferroelectric low molecular liquid crystal, ferroelectric high molecular liquid crystal, ferroelectric low molecular liquid crystal and high molecular liquid crystal and / or Polymeric liquid crystals exhibiting all ferroelectric properties can be used, such as mixtures with common polymers or mixtures of these with normal low-molecular liquid crystals. Among the ferroelectric polymer liquid crystals, for example, a side chain type ferroelectric polymer liquid crystal having a chiral smectic C phase is preferably used.

Examples of the ferroelectric liquid crystal compound include desiloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC), hexyloxybenzylidene-P'-amino-2-chloropropylcinnamate (HOBACPC). And 4-o- (2-methyl)-
Butyl resorcylidene-4'-octylaniline (MB
RA8) etc. are mentioned. When a device is formed using these materials, the liquid crystal compound is SmC ^* phase or SmH
^* Use in a temperature condition that causes a phase. I phase, J phase, G
It is also possible to use a ferroelectric liquid crystal that appears in the phase or K phase. Further, the ferroelectric liquid crystal composition may contain an adhesive, a viscosity reducer, a non-liquid crystal chiral compound, a dye, etc., if necessary.

Examples of the flexible electrode substrate with electrodes include crystalline polymers such as uniaxially or biaxially oriented polyethylene terephthalate, amorphous polymers such as polysulfone and polyethersulfone, polyolefins such as polyethylene and polypropylene, and polycarbonate. Examples thereof include polyamides such as nylon. Among these, uniaxially or biaxially stretched polyethylene terephthalate and polyether sulfone are particularly preferable. In the present invention, the two substrates may be made of the same material as each other or may be made of different materials, but usually at least one of the two substrates is It is optically transparent and is used with a transparent electrode.

The material for forming the liquid crystal driving electrode group formed on the flexible substrate is not particularly limited as long as it is a material having conductivity, but at least one of the electrodes has both conductivity and transparency. It is preferable to use a material having properties. Specifically, for example, ITO (IndiumTin) made of indium oxide or a mixture of indium oxide and tin oxide is used.
A transparent electrode such as an Oxide) film or a NESA film is preferably used. The method for forming the liquid crystal driving electrode on the flexible substrate is not particularly limited, and it is formed by a conventionally known method such as vapor deposition or sputtering. The method for holding the ferroelectric liquid crystal material is not particularly limited. Also, the holding method is not particularly limited in the case of a nematic liquid crystal material. Normal T
N, STN cells or polymer dispersion type may be used.

As the protective plate 4 arranged on the front surface side of the substrate 2, a material having at least one of electric conductivity and heat conductivity, such as ordinary ITO, NESA, or a multimetal film, is used. In the case of having a polarizing plate, the position of the polarizing plate is
It may be on either the upper surface or the lower surface of the protective plate 4, and may be arranged on the liquid crystal display panel side.

As the reflection plate or the support plate 4 arranged on the back surface side of the substrate 3, a planar heating element having at least one of electrical conductivity and heat conductivity is used. As a method of providing the sheet heating element with electric conductivity and / or heat conductivity, there are methods of using Al, plating, and using a conductive paint. In the case of using Al, the planar heating element is formed by vapor deposition of Al, stacking of Al foil, and the like, but by using Al, it can be used also as a reflection plate. In the case of the plating method, CuNi plating or Cr plating is performed by chemical plating or a combination of chemical plating and electroplating.

In the case of the method using a conductive paint, a paint in which a conductive filler is dispersed is used. here,
As the conductive filler, metal, nonmetal, metal oxide,
Polymeric inorganic fillers, composite fillers composed of inorganic-inorganic and inorganic-organic compounds, surfactants, polymer electrolytes, conductive polymers, organic conductor organic fillers are used. It is also possible to use carbon as the conductive filler and use conductive rubber (plastic) containing this carbon filler in rubber (plastic). By doing so, it is possible to easily obtain a temperature of about 40 ° C. by energizing a sheet having a specific resistance of about 4 Ω · cm, and to form a sheet heating element that generates heat by itself.

Next, an example of a sheet heating element having a self-temperature adjusting function will be described. In the planar heating element formed of the conductive rubber (plastic) described above, when not conductive, the carbon fillers contained in the rubber (plastic) are in contact with each other to form a conduction path. Therefore, when electricity is applied, Joule heat is generated and the conductive rubber functions as a heating element. However, since the conductive rubber heats up and expands with heat generation, when the temperature exceeds a certain temperature, the contact between the contained carbon fillers is released and the current-carrying path is cut off. As a result, the conductive rubber stops generating heat and cools down and contracts.
The carbon fillers contact again. The conductive rubber keeps the temperature constant by repeating the switching operation as described above. That is, the sheet heating element made of conductive rubber (plastic) has a self-temperature adjusting function. By disposing such a sheet heating element on the back surface of the liquid crystal display panel, it becomes possible to keep the temperature of the liquid crystal display panel constant. The switching temperature, that is, the temperature of the liquid crystal display panel, is rubber (plastic).
It can be arbitrarily adjusted depending on the amount of the conductive filler and the degree of polymerization of the matrix polymer. Also,
When the above-mentioned Al foil is laminated on such a conductive rubber or a conductive paint is applied to give a metallic luster, it can be used as a reflector.

As the sheet heating element, in addition to those having rubber or plastic as a matrix, a metal including a heat transfer tube, an electric heating foil, an electric heating wire, and an electric heating fiber (conductive metal fiber, metal composite fiber, metal coating fiber) Product-based products, electrothermal powder molded products, inorganic product-based products consisting of electrothermal fibers (composite fiber, coating fiber), electrothermal paint, electrothermal sheet (conductive plastic sheet, composite plastic sheet), electrothermal fiber (conductive plastic) Polymer products such as fibers, conductive filler composite plastic fibers, metal mixed woven plastic fibers) can be used.

[0018]

EXAMPLES The liquid crystal display panel of the present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Example

[0019]

[Chemical 1]

The above liquid crystal composition was patterned into stripes as a 25% by weight dichloromethane solution.
A coating film is formed on the electrode surface of a polyether sulfone (PES) substrate with a TO electrode using a microgravure coater,
After evaporation of the solvent, a dot-matrix type liquid crystal display panel was produced by laminating the substrate of the same type on which nothing was applied. The liquid crystal display panel has a 5.08 mm pitch (electrode width 4.88 mm).
mm, gap 0.20 mm), a dot matrix type with 24 scanning lines and 72 signal electrodes. The size of the liquid crystal display panel is about 150 mm × 400 mm. Response time t of the liquid crystal device with respect to the measured temperature (° C)
_{When 10-90} was measured, the results shown in Table 1 below were obtained. [Table 1] ───────────────────────────────── Measurement temperature (℃) 10 20 30 40 ──── ───────────────────────────── Response time t _10-90 12ms 3.1ms 700μs 280μs ───────── ──────────────────────── As shown in the results in Table 1, the temperature dependence is large. The response time t _10-90 is the time required for the change in the light transmittance to change from 10% to 90% when the liquid crystal element is arranged under crossed Nicols and a driving voltage of ± 10 V is applied. Defined as

The sheet heating element was manufactured as follows.
Ethylene-ethyl acrylate copolymer (EEA resin,
Made by Nippon Unicar Co., Ltd. (Product name: DPDS6182) 65
25% by weight of carbon black (manufactured by Mitsubishi Kasei Co., Ltd., trade name: Diamond Black E, average particle size 48 nm)
Was kneaded for 20 minutes at a temperature of 125 ° C. using a pressure kneader (manufactured by Moriyama Seisakusho Co., Ltd., 3 liter volume),
Formed into a sheet with a thickness of 0.5 mm, 15 cm x 100 c
Cut out to m. Attach electrodes and lead wires of tin flattened copper net wire (0.5 mm ² ) to both ends of the long side of this sheet, and laminate PET adhesive film (silicone adhesive is applied on only one surface) on both sides. Thus, a sheet heating element (element) was manufactured. In addition, 9 is provided on one surface of the sheet heating element.
An initial resistance value at the time of energization was 50Ω, which was provided with a μmAl foil and had a function of a reflection plate.

This sheet heating element was laminated on a dot matrix panel to obtain a desired liquid crystal display panel. When the liquid crystal display panel configured as described above is used indoors,
A response of 00 μs was obtained. 6 even when the outside temperature is 0 ° C
A response of 00 μa was obtained. Contrast is 1 each
It was 1 and 10.

[0023]

As described above, according to the present invention, the temperature of the liquid crystal display panel can be kept constant without requiring complicated control at a low cost. As a result, excellent display performance can always be obtained regardless of the usage environment.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of an embodiment of a liquid crystal display panel according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal composition 2, 3 ... Substrate with electrodes 4 ... Protective plate 5 ... Reflector or support plate

Claims (5)

[Claims] 1. A liquid crystal display characterized in that a planar heating element having at least one of electrical conductivity and thermal conductivity is disposed on the back surface side of a liquid crystal display panel in which a liquid crystal composition is sandwiched between substrates with electrodes. panel. 2. The liquid crystal display panel according to claim 1, wherein a protective plate having at least one of electrical conductivity and heat conductivity is arranged on the front surface side of the liquid crystal display panel in which the liquid crystal composition is sandwiched between substrates with electrodes. 3. The liquid crystal display panel according to claim 1, wherein the sheet heating element arranged on the back surface side of the liquid crystal display panel has a self-temperature adjusting function. 4. The liquid crystal display panel according to claim 1, wherein a supporting plate, a reflecting plate, a protective plate or the like is used as the planar heating element. 5. The liquid crystal display panel according to claim 1, 2, 3 or 4, wherein the liquid crystal composition is a ferroelectric liquid crystal composition.