JPH09101517A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which does not cause decrease in the contrast ratio or change in the background color in a wide temp. range. SOLUTION: This liquid crystal display device is a film-compensation type STN liquid crystal display device consisting of a STN liquid crystal cell in which liquid crystal molecules are arranged in a twisted state with 100-300 deg. twisted angle between two substrates, a pair of polarizing plates disposed on both sides of the liquid crystal cell and at least one or plural sheets of film-type optical phase difference plates disposed at least one side of the liquid crystal cell between the cell and the polarizing plate. The film-type optical phase difference plate is produced by dispersing a side-chain polymer liquid crystal in another polymer film. The change rate of retardation with temp. of the optical phase difference plate is smaller than that of the liquid crystal cell and it decreases at high temp.

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 device using an optical retardation plate, and more particularly to a liquid crystal display device using a film optical phase plate suitable as a color compensating plate for an STN liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been widely adopted as display devices for automobile instruments, personal computers, word processors, data terminals and the like. Many of them use a super twist nematic (hereinafter sometimes referred to as STN) mode in order to prevent reduction in contrast and narrowing of viewing angle characteristics because a large capacity display is performed. However, STN has a drawback that it displays in color because it utilizes the birefringence effect.

Therefore, a polymer film compensation type liquid crystal display device for compensating for coloring due to birefringence and performing black and white display has been developed. The compensating polymer film contains a specific polymer component, and is made to have anisotropy in refractive index by stretching and orientation.

However, the display element has a difference in temperature characteristic between Δn of the polymer component of the film optical phase plate and Δn of the liquid crystal in the liquid crystal display device. The compensation performance deteriorates due to the difference in the retardation temperature change, and there is a drawback that the contrast, the transmittance, the viewing angle characteristics are deteriorated, and the background color is changed. That is, in general, a polymer component having a refractive index anisotropy Δn has a remarkably small temperature change of birefringence as compared with a liquid crystal used in a liquid crystal display device, and the difference in the characteristics deteriorates the compensation performance at a high temperature or a low temperature. There is a defect that the contrast and transmittance of the display element, the viewing angle characteristics are deteriorated, and the background color is changed. That is, a liquid crystal display device that performs black-and-white display using a film optical phase difference plate has a difference in temperature characteristic of Δn between a polymer component of the film optical phase plate and liquid crystal in the liquid crystal display device, and therefore, the liquid crystal display element and the film optical phase difference. Since the retardation plate has different retardation temperature changes, there is a problem that the contrast ratio, the transmittance, the viewing angle characteristics are deteriorated, and the background color is changed depending on the temperature.

As a method for solving these problems, conventionally, an acrylic film (polymethylmethacrylate, P
Those using MMA are known (Japanese Patent Laid-Open No. 6-2
7433). However, the retardation plate using PMMA has limited temperature characteristics of retardation in terms of material, the film optical retardation plate becomes thicker due to the small birefringence of the polymer itself, and the wavelength dispersion due to the different molecular structure from liquid crystal. However, there was a problem that the contrast was lowered due to the influence of. Further, JP-A-5-257013 describes that a retardation film is obtained by dispersing liquid crystal molecules in a polymer film and stretching the polymer film together. However, there is no description of specifically what kind of characteristics the liquid crystal compound and the polymer have in combination when an excellent effect is obtained. In addition, there is no description of what characteristics the polymer-liquid crystal molecular dispersion film having not been mounted on the liquid crystal display device can bring about an excellent effect when combined with a liquid crystal cell.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves such a problem and adjusts the temperature change of the birefringence of the film optical retardation plate and the liquid crystal display element to an optimum value to obtain a wavelength similar to that of the liquid crystal. An object of the present invention is to provide a liquid crystal display device capable of substantial temperature compensation in a wide temperature range by using a film optical retardation plate that requires dispersion. In particular, it is an object of the present invention to provide a liquid crystal display device having higher display quality in a wide range of temperatures by providing a film optical retardation plate with temperature characteristics and wavelength dispersion extremely similar to those of liquid crystal. Another object of the present invention is to provide a practical liquid crystal display device in which the film optical retardation plate has a wide stable temperature range as a film and a wide range of temperature conditions. Further, another object of the present invention is to provide a liquid crystal display device having an increased practical value by providing a practical optical retardation plate that is easy to mold as a film optical retardation plate.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a film optical retardation plate for compensating for coloring in a film compensation type liquid crystal display device to perform black and white display. Retardation (Δn
A film in which a side chain type polymer liquid crystal having a temperature characteristic equivalent to that of the liquid crystal composition in the liquid crystal display element is dispersed in a film of another polymer (hereinafter, referred to as a polymer liquid crystal dispersion film) The present invention provides a liquid crystal display device characterized by obtaining good display at high and low temperatures.

That is, the present invention is the invention described below. [1] Liquid crystal molecules between 100 ° to 300 ° between both substrates
STN liquid crystal cell which is twisted at the twist angle of
In a film compensation type STN liquid crystal display device in which a pair of polarizing plates arranged on both sides of the liquid crystal cell and one or a plurality of film optical retarders are arranged on at least one side between the liquid crystal cell and the polarizing plate, A liquid crystal display device, wherein the phase difference plate is a film in which a side chain type polymer liquid crystal is dispersed in a film of another polymer.

[2] The liquid crystal display device as described in [1], wherein the temperature change rate of the retardation of the film optical retardation plate is less than that of the liquid crystal cell and decreases at high temperature.

[3] The rate of change R _80/25 of the retardation at 80 ° C. with respect to the retardation at 25 ° C. of the film optical retardation plate is as follows with respect to Tc (clearing point, unit ° C.) of the liquid crystal in the liquid crystal cell. The liquid crystal display device according to [2], which satisfies the relationship.

[Formula 3] 0.005Tc + 0.06 ≦ R _80/25 ≦ 0.0
05Tc + 0.46 and R _80/25 <1 [4] The rate of change R _80/25 of retardation at 80 ° C. relative to the retardation of the film optical retardation plate at 25 ° C. is Tc of the liquid crystal in the liquid crystal cell (clearing point, unit ° C. ), The liquid crystal display device according to [2] is characterized by satisfying the following relationship.

[Formula 4] 0.005Tc + 0.15 ≦ R _80/25 ≦ 0.0
05Tc + 0.33 and R _80/25 <1

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The liquid crystal layer used in the liquid crystal display element of the present invention is a super twisted nematic liquid crystal display element. In this case, specifically, a nematic liquid crystal having a positive dielectric constant anisotropy containing an optical rotatory substance is sandwiched between a pair of transparent electrode substrates arranged substantially in parallel, and twisting of liquid crystal molecules between both electrodes is caused. The angle may be 100 ° to 300 °. This is 100 °
If it is less than 300 ° C., there is little improvement in the contrast ratio when performing time-division driving at high duty, which requires a sharp change in transmittance, and conversely, if it exceeds 300 °, hysteresis or a domain that scatters light is likely to occur. .

Further, the retardation of the liquid crystal layer is particularly 0.
It is preferably 4 μm to 1.5 μm. When a black and white display is made by adding an interference color compensation layer, if the retardation is less than 0.4 μm, the transmittance at ON is low, and a bluish display color is likely to occur, and if it exceeds 1.5 μm, the hue at ON is displayed. Is changed from yellow to red, and it is difficult to display in black and white. Particularly, in applications where achromatic display colors are strictly required, the retardation is 0.5 μm to 1.0 μm.
It is preferably set to μm.

Basic structure of liquid crystal cell sandwiching the liquid crystal layer
Is as follows. For substrates such as plastic and glass
ITO patterned on the surface in a desired pattern
(In _TwoO_Three-SnO_Two), SnO_TwoTransparent electrodes such as
The substrate with the electrodes is removed. The electrode layer is
May be patterned accordingly and used as a common electrode
When it can be used, it may be a solid electrode. Electrode layer
The method of forming the is not particularly limited to this,
From the viewpoint of making the layer thickness uniform, vapor deposition method, sputtering method, etc.
It is preferably used.

In the present invention, an insulating film such as SiO ₂ , TiO ₂ or the like, a retardation film, a polarizing film, a reflecting film, a photoconductive film or the like may be formed on or under the electrode, if necessary. .
A typical example of the transparent electrode shape is 64
0 stripe-shaped electrodes are formed, and 400 stripe-shaped electrodes are formed on the other substrate so as to be orthogonal thereto, and a display like 640 × 400 dots is made. Further, it is also possible to display 640 × 400 dots in full color by arranging the 640 striped electrodes as a set of three to form 1920 striped electrodes and disposing RGB color filters.

The surface of the substrate with this electrode has a rabbi surface.
Film such as polyimide, polyamide, etc.
An alignment control film made of a film of SiO or the like is formed. table
Depending on the display mode, it may be necessary to apply a vertical alignment agent.
In some cases. The above-mentioned liquid crystal is prepared by preparing the two substrates described above.
It is designed to sandwich the layers. At this time, the electrodes and orientation control
TiO for preventing short circuit between substrates with the control film_Two, SiO
_Two, Al_TwoO_ThreeInsulating film such as
l, Cr, Ti and other low resistance lead electrodes,
A color filter may be laminated on or under the electrodes.

Usually, a polarizing plate is arranged on at least one of the outer sides of this substrate. The polarizing plate itself is generally placed outside the substrate that constitutes the cell, but if the performance permits, the substrate itself may be constituted by a polarizing plate or provided as a polarizing layer between the substrate and the electrode. Good.

In the present invention, either a transmission type or a reflection type can be used, and its application range is wide. When used as a transmissive type, it is preferable to arrange a light source on the back side. Further, a light guide and a color filter may be used in combination with the light source. Furthermore, in the case of using the transmissive type, the background portion other than the pixels can be covered with a light shielding film by printing or the like. Further, it is also possible to use the light-shielding film and perform the opposite driving so that the selected waveform is applied to a portion which is not desired to be displayed.

Furthermore, in the present invention, it is possible to use a color filter together. This color filter is
By forming it on the inner surface of the cell, a more accurate color display can be performed without causing a shift due to the viewing angle. Specifically, it may be formed below the electrode, or may be formed above the electrode. Further, a color filter or a color polarizing plate for color correction may be used, a dye may be added to the liquid crystal, or illumination having a specific wavelength distribution may be used. In the present invention, driving is performed by connecting driving means for applying a voltage to the electrodes of the liquid crystal cell having such a configuration. In addition to the above, the present invention can be applied to various techniques used in a normal super twist nematic liquid crystal display device within a range that does not impair the effects of the present invention.

FIG. 1 shows a basic structure of a liquid crystal display device according to the present invention.
A cross-sectional view of an example is shown. In the figure, 1 and 2 are a pair of polarizing plates,
Reference numeral 3 is a liquid crystal cell that performs a specific display by applying a voltage.
You. Here, as the liquid crystal preferably used for the liquid crystal cell,
Suitable for temperature characteristics of polymer dispersed film and retardation
A liquid crystal with a relatively high Tc (clearing point) is often used for
Specifically, a liquid crystal having Tc in the range of 80 ° C to 130 ° C is preferable.
No. Reference numeral 4 denotes a film optical phase plate. 5 and 6 are liquids
Glass substrates that make up the crystal cells, 7 and 8 are formed on the inner surface
ITO (In_TwoO_Three-SnO_Two), SnO_TwoEtc.
Transparent electrodes, 9 and 10 are films of polyimide, polyamide, etc.
Formed by rubbing or obliquely evaporating SiO, etc.
Orientation control film, 11 and 12 are a transparent electrode and an orientation control film.
Ti, which is provided as necessary to prevent short circuit between substrates
O_Two, SiO _Two, Al_TwoO_ThreeInsulating film such as 13 and these are
Sealing material for sealing around the two substrates 1 and 2,
Reference numeral 14 indicates a liquid crystal layer.

Conventionally, a film compensation type liquid crystal display device uses a polymer having a rigid molecule in the main chain such as polycarbonate for the film optical phase plate, and therefore the liquid crystal in the liquid crystal display element and the component of the film optical phase plate. Due to the difference in the temperature characteristics of Δn with the polymer, the difference in the amount of change in retardation at a high temperature causes a decrease in contrast and the like. Therefore, in the present invention, in order to solve these problems, a film optical retardation plate in which a side chain type polymer liquid crystal is dispersed in another polymer film was prepared. It is known that the side chain type polymer liquid crystal has a mesogenic group showing liquid crystallinity in the side chain, and the thermal behavior of the side chain is almost the same as that of the liquid crystal in the cell.

However, when a film optical retardation plate is prepared from a side chain type polymer liquid crystal alone, there are problems in the reliability and film forming property of the film optical retardation plate due to the characteristics of the polymer. There were problems such as having to be caught. Therefore, in the present invention, the side chain type polymer liquid crystal is further formed into a film or dispersed in another polymer having stable reliability to enhance the reliability of the film optical retardation plate, improve the film forming property, and support it. A retardation plate that can obtain stable retardation even if the body is lost was created. At this time, the retardation can be adjusted by stretching the film without aligning the molecules by an alignment control film or a magnetic field method because the film optical retardation plate itself has a certain strength. Further, by using these methods and changing the polymer liquid crystal, it is possible to easily prepare film retardation plates having different temperature characteristics of retardation.

The polymer film used in the present invention is preferably a polymer that does not change its optical properties or shape depending on the temperature range of use of the liquid crystal display device or the temperature of the step of laminating with the liquid crystal cell. For a thermoplastic engineering polymer having a somewhat high temperature or a polymer to which a plasticizer is added, a polymer having a somewhat high flow temperature is preferably used. The glass transition temperature or softening temperature required for the matrix is preferably 80 ° C to 250 ° C, and 90 ° C.
-200 degreeC is more preferable.

Examples of polymers satisfying these conditions are polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, ethylene vinyl alcohol copolymer, polyethylene terephthalate and polyethylene naphthalate. Preferably polycarbonate, polysulfone, 3
Cellulose acetate and polyethylene terephthalate are exemplified. The polymer liquid crystal used in the present invention has good dispersion state and refractive index anisotropy in the polymer film.
A side chain type polymer liquid crystal having a mesogen group in its side chain is preferably used. The degree of polymerization of these polymer liquid crystals is preferably 4 to 30, and more preferably 5 to 20.

The polymer liquid crystal used in the present invention has a main chain structure of methacrylate type, acrylate type,
The polysiloxane type is exemplified, but the polysiloxane type is preferable. As the mesogen group used in the present invention, a known one can be used, and it is bonded to the main chain of the polymer liquid crystal by an alkylene group having 1 to 10 carbon atoms called a spacer or an alkylene ether. Examples of the method for synthesizing a polymer liquid crystal having a mesogen group in its side chain include a method of polymerizing a monomer having a mesogen group and a method of adding a mesogen group to a polymer. Further, these side chain type polymer liquid crystals may be used alone or as a mixture. The side chain group of the side chain type polymer liquid crystal does not have to be a single side chain group, and may be a copolymer having different side chains.

Next, a method for producing a polymer film in which a polymer liquid crystal is dispersed will be described. The method for mixing the polymer liquid crystal and the polymer is not particularly limited, but it is preferable to mix them in a solution state from the viewpoint of uniformity. Specifically, there is a method in which a polymer is dissolved in a solvent and a polymer liquid crystal is dissolved and mixed therein. The solvent used preferably has a high solubility in the polymer or polymer liquid crystal. The polymer film is formed by solvent casting method in which it is cast from a solution, extrusion molding method in which it is kneaded in a solid state and extruded into a film from a die, calendering method in which it is kneaded in a solid state and then formed into a film by a calendar roll, and press. A press molding method for forming a film is exemplified. Among these, the solvent casting method, which is excellent in film thickness accuracy, is preferable.

Examples of the stretching method for stretching the film after film formation while heating include a tenter stretching method, a roll stretching method, and a roll compression stretching method. The tenter stretching method and the inter-roll stretching method are preferable from the viewpoint of uniformity of the film surface. The method of heating the film is not particularly limited. The heating temperature is appropriately selected depending on the matrix polymer used, the transition temperature of the liquid crystal, and the temperature change rate of the retardation of the obtained polymer liquid crystal dispersion film, but 90 ° C. or higher is preferable.

The reason why birefringence can be compensated reliably in a wide temperature range by the present invention is considered as follows. In the present invention, first of all, in order to eliminate the drawback of different temperature changes in retardation of the liquid crystal display element and the film optical retardation plate, a film optical retardation plate for compensating for coloring and performing black and white display is a polymer liquid crystal dispersion film. With this, a film optical retardation plate having a temperature characteristic of Δn similar to the temperature characteristic of retardation in a liquid crystal display device can be obtained. In this way, the retardation difference between the liquid crystal display element and the film optical retardation plate does not change at high and low temperatures, and it becomes possible to prevent changes in the contrast ratio and background color. In particular, from the viewpoint of precise temperature compensation, it is preferable to set the width of the rate of temperature change of the retardation of the film optical retardation plate according to the clearing point of the liquid crystal. It is preferable to set such that the relationship [] is established. Further, it is preferable that the rate of temperature change of retardation of the film optical retardation plate does not exceed that of the liquid crystal cell in terms of contrast ratio at high temperature. In addition, 2 to 5 film optical retardation plates can be stacked and used. By doing this,
(1) Optical compensation is better when two or more films are used than when using one film type, and (2) high reliability is obtained by combining with other highly reliable films.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples.
However, the present invention is not limited to these. Comparative Example 1 As a first substrate, an ITO transparent film provided in a glass substrate shape was used.
By patterning the bright electrode into a stripe pattern and using the transfer method
SiO_TwoForm an insulating film to prevent short circuit
Spin the overdubber of the card and rub it
A substrate on which an orientation control film was formed was prepared. Second substrate
The ITO transparent electrode provided on the glass substrate as
Patterned in stripes so that it is orthogonal to the substrate 1
SiO _TwoThe insulating film is formed and the polyimide overcoat is
-The crossing angle 6 with the rubbing direction of the first substrate
A substrate on which an alignment control film is formed by rubbing so that the angle becomes 0 °.
I made a board.

A liquid crystal cell in which the periphery of these two substrates is sealed with a sealing material is formed, and a nematic liquid crystal (T _c = 110 ° C.) having a positive dielectric anisotropy is injected into the liquid crystal cell. 2
The inlet was sealed so that the liquid crystal layer was a left-handed helix with a twist of 40 °. The retardation of the liquid crystal layer in this example is 2
It was 880 nm (measurement wavelength: 590 nm) at 5 ° C. Polycarbonate (made by Teijin, brand name Panlite C140
0) is dissolved in methylene chloride to 20 wt%,
A film was obtained by casting from an applicator with a gap of 500 μm. When the obtained film was stretched 1.2 times at 180 ° C, the retardation at 25 ° C was 397n.
m film optical retardation plate was obtained. The retardation did not change even when the obtained film optical retardation plate was heated to 80 ° C. FIG. 1 is a diagram schematically showing the liquid crystal display element used this time. Reference numerals 1 and 2 are a pair of polarizing plates, 3 is a liquid crystal cell, and 4 is a film optical retardation plate. (A) of FIG. 2,
(B) is the polarization axis direction of the upper polarizing plate as viewed from above, the optical axis direction of the film optical phase plate and the long axis direction of liquid crystal molecules on the upper side of the liquid crystal layer, and the polarization axis direction of the lower polarizing plate and the liquid crystal layer. FIG. 3 is a plan view showing relative positions in the long axis direction of liquid crystal molecules on the lower side.

Here, θ ₁ is the counterclockwise direction of the polarization axis 16 of the upper polarizing plate as viewed from the long axis direction of the liquid crystal molecules 15 on the upper side of the liquid crystal layer, and _{1 is} the liquid crystal molecule 1 on the upper side of the liquid crystal layer.
The optical axis direction 17 of the birefringent plate viewed from the long axis direction of 5 is measured counterclockwise as θ ₂ , and 1 of the liquid crystal molecules on the lower side of the liquid crystal layer.
The direction of the polarization axis 19 of the lower polarizing plate viewed from the long axis direction of 8 is measured clockwise, and the direction of the lower polarizing plate of the liquid crystal molecule of the lower side of the θ ₃ liquid crystal layer viewed from the long axis direction of 18 Birefringent plate 20
Let θ ₄ be the clockwise direction of. Comparative Example 1
Θ ₁ , θ ₂ , θ ₃ , and θ ₄ are 130 ° and 10
They are 0 °, 40 ° and 100 °.

Example 1 In the liquid crystal display device of Comparative Example 1, a film optical retardation plate obtained by dispersing a side chain type polymer liquid crystal in a polymer film was used in place of the polycarbonate film optical retardation plate. The film optical retardation plate was obtained as follows. A linear ratio of a linear siloxane liquid crystal oligomer having a mesogenic group in its side chain (showing a nematic phase and a nematic / isotropic phase transition temperature of 66 ° C.) and a polycarbonate (manufactured by Teijin: trade name Panlite C1400) are in a weight ratio. No. 7:93, and the mixture was dissolved in methylene chloride to 20 wt%. The resulting solution is 50
A film was obtained by casting from an applicator having a 0 μm gap. The obtained film was stretched 1.6 times at 180 ° C. to obtain a polymer liquid crystal dispersed film having retardations at 25 ° C. and 80 ° C. of 397 nm and 327 nm, respectively.

This film optical retardation plate was used in the same manner as in Comparative Example 1, where θ ₁ , θ ₂ , θ ₃ and θ ₄ were 130 ° and 10 °, respectively.
When the same measurement as in Comparative Example 1 was performed at 0 °, 40 ° and 100 °, the results shown in Table 1 were obtained. Further, even at a low temperature, changes in contrast ratio and background color were smaller than those of the conventional film compensation type liquid crystal display device. Further, here, the driving condition was 1/32 Duty-1 / 7 Bias.

[0033]

[Table 1]

[0034]

The present invention eliminates the disadvantages of the conventional film type liquid crystal display device, such as the decrease of the contrast ratio at high temperature and the change of the background color, thereby reducing the contrast ratio and the background color in a wide temperature range. It has an excellent effect that a liquid crystal display device which does not change can be obtained. In addition to this, it is also considered to be effective for viewing angle characteristics at high temperatures.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a liquid crystal display element according to the present invention.

FIG. 2 is a plan view showing relative positions in the long axis direction of the upper and lower liquid crystal molecules when viewed from above, the polarization axis direction of the polarizing plate, and the optical axis direction of the film phase plate.

[Explanation of symbols] 1 Polarizing plate 2 Polarizing plate 3 Liquid crystal cell 4 Film optical retarder 5 Glass substrate 6 Glass substrate 7 Transparent electrode 8 Transparent electrode 9 Orientation control film 10 Orientation control film 11 Insulation film 12 Insulation film 13 Sealant 14 Liquid crystal layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Kuwahara 6 Kitahara, Tsukuba-shi, Ibaraki Sumitomo Chemical Co., Ltd.

Claims (4)

[Claims] 1. Liquid crystal molecules between 100 ° to 3 between both substrates.
STN liquid crystal cells twist-aligned at a twist angle of 00 °, and a pair of polarizing plates arranged on both sides of the liquid crystal cell,
A film compensation type ST in which one or more film optical retardation plates are arranged on at least one side between a liquid crystal cell and a polarizing plate.
In the N liquid crystal display device, the film optical retardation plate is a film in which a side chain type polymer liquid crystal is dispersed in a film of another polymer, which is a liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the temperature change rate of the retardation of the film optical retardation plate is less than that of the liquid crystal cell and decreases at high temperature. 3. The retardation change rate R _{80/25 at} 80 ° C. relative to the retardation at 25 ° C. of the film optical retardation plate is Tc (clearing point,
The liquid crystal display device according to claim 2, wherein the following relationship is satisfied with respect to a unit of ° C. [Formula 1] 0.005Tc + 0.06 ≤ R _80/25 ≤ 0.0
05Tc + 0.46 and R _80/25 <1 4. The rate of change R _80/25 in retardation at 80 ° C. relative to the retardation at 25 ° C. of a film optical retardation plate is Tc (clearing point,
The liquid crystal display device according to claim 2, wherein the following relationship is satisfied with respect to a unit of ° C. [Formula 2] 0.005Tc + 0.15 ≦ R _80/25 ≦ 0.0
05Tc + 0.33 and R _80/25 <1