JPH07294901A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the color liquid crystal display element having a high response speed by providing oriented films, liquid crystal, and polarizing plates and specifying their constitution. CONSTITUTION:A transparent counter electrode 7 facing each picture element electrode 3 of a lower substrate 1 is formed on an upper substrate 2. A first oriented film 8 is provided on the electrode forming face of a lower substrate 1, and a second oriented film 9 is formed on the electrode forming face of the upper substrate 2. Liquid crystal 11 is charged in the area surrounded with the lower substrate 1, the upper substrate 2, and a seal material 10. The crossing angle between an axis 14a of transmission of an upper polarizing plate 14 and the direction of orientation treatment 8a of the lower oriented film 9 is set to 130 deg. or 40 deg., and that between the direction of orientation treatment 9a of the upper oriented film 9 and the direction 8a is set to 90 deg. (the twisting angle of liquid crystal 11 is 90 deg.), and that between an axis 13a of transmission of a lower polarizing plate 13 and the direction 8a is set to 150 deg. or 155 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device for displaying a color image by controlling the birefringence of liquid crystal.
In particular, the present invention relates to a color liquid crystal display device having a fast response speed, stable operation, and a wide viewing angle.

[0002]

2. Description of the Related Art Super twisted nematic (ST
The N) type liquid crystal display element has, for example, a twist angle of liquid crystal molecules of 180 ° or more, a product Δn · d of optical anisotropy Δn and a liquid crystal layer thickness d of about 0.7 μm to 1.1 μm, and Coloring due to refraction occurs. In this STN type liquid crystal display element, substantially two-color display of black and yellow or blue and white is possible. Japanese Patent Application Laid-Open No. 2-20142 discloses a multi-color display using such an STN type liquid crystal display element.
2, the twist angle of the liquid crystal molecules of nematic liquid crystal is 18
The range of 0 ° to 360 ° is set, and Δn · d of the liquid crystal layer is 1.
An STN type liquid crystal display element capable of full color display by setting the thickness to 1 μm or more is disclosed.

[0003]

However, in the STN type liquid crystal display element disclosed in the above publication, the response angle is slow because the twist angle of the liquid crystal molecules is as large as 180 ° to 360 °. However, there is a problem in that the response speed is insufficient to achieve. Further, since the twist angle of the liquid crystal is large, the alignment state of the liquid crystal molecules is likely to be unstable, and the material of the alignment film is limited, for example, the pretilt angle needs to be 5 ° or more, which makes the manufacturing difficult. Become. Further, since a liquid crystal having a large elastic constant ratio K33 / K11 is difficult to be aligned, it is necessary to select a liquid crystal having a small elastic constant ratio, and there is a problem that the selection range of the liquid crystal becomes narrow.

Further, since the liquid crystal layer has a large Δn · d, it is inevitably necessary to thicken the liquid crystal layer or use a liquid crystal material having a large Δn, resulting in a narrow viewing angle.
Further, since the electric field strength becomes weaker as the liquid crystal layer becomes thicker, the response speed becomes slower. Also, Δn
Since d is large, the change in the retardation with respect to the change in the applied voltage or the change in the liquid crystal layer thickness becomes large, and the display color becomes uneven due to the variation in the liquid crystal layer thickness and the variation in the voltage applied to each part of the liquid crystal layer. I will end up. On the other hand, it is difficult to keep the thickness of the liquid crystal layer constant in the manufacturing process, and it is also difficult to eliminate subtle fluctuations in the power supply voltage, so that there is a problem that a desired color cannot be stably displayed.

There is a liquid crystal display element using a color filter as a liquid crystal display element for displaying a color image, but a color filter for three primary colors is required, and the number of dots is tripled (3
There is a problem in that the manufacturing process is complicated such that one pixel is required for each dot and the light is attenuated by the filter, so that the display becomes dark.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a color liquid crystal display device having a high response speed. Another object of the present invention is to provide a liquid crystal display device capable of stably displaying a desired color. Another object of the present invention is to provide a liquid crystal display device having a wide viewing angle. Another object of the present invention is to improve a liquid crystal display device that controls a birefringence to display a color image.

[0007]

In order to achieve the above object, a liquid crystal display element of the present invention is provided with a first and a second substrate arranged to face each other, and a facing surface of the first and the second substrate. A first alignment film formed on the first substrate and a first alignment film formed on the first substrate and having an alignment treatment in a first direction; Second electrode and the second
Formed on the substrate of substantially 9 with respect to the first direction.
The second alignment film, which has been subjected to the alignment treatment in the second direction intersecting at 0 °, is disposed between the alignment films, and is substantially 90 due to the alignment regulating force of the first and second alignment films. ° Twist-aligned liquid crystal and an optical axis disposed outside the first substrate, the optical axis of which is substantially 15 with respect to the first alignment treatment direction.
A first polarizing plate arranged to intersect at 0 ° or 155 °, and arranged outside the second substrate, and its optical axis is substantially 130 ° with respect to the first alignment treatment direction; It is characterized by comprising a second polarizing plate arranged so as to intersect at 40 °.

The liquid crystal has, for example, an optical anisotropy Δn.
And the thickness d is 0.7 μm or more and less than 1.1 μm. Further, a retardation plate for improving the viewing angle may be arranged between the first and second polarizing plates.

[0009]

According to the above construction, by controlling the voltage applied between the electrodes facing each other, the alignment state of the liquid crystal molecules is controlled, the birefringence of the liquid crystal is controlled, and an arbitrary display color can be obtained. it can. In particular, the product of optical anisotropy Δn and thickness d Δn ·
By using a liquid crystal having d of 0.7 or more, full color display is possible. The twist angle of liquid crystal molecules is as small as 90 °, and Δn · d of liquid crystal is 1.1 μm.
Since the liquid crystal layer thickness d is small, the response speed is fast and a liquid crystal display device suitable for displaying moving images can be obtained. Further, the use of the retardation plate can widen the viewing angle.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) First, the structure of a liquid crystal display element according to the first embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view of the liquid crystal display element of this embodiment, FIG. 2 is a plan view of a substrate on which pixel electrodes and thin film transistors are formed, and FIG.
4A to 4C are plan views showing the relationship between the alignment treatment direction and the optical axis of the polarizing plate, and FIGS. 4A to 4C show the relationship between the alignment treatment direction and the optical axis of the polarizing plate. FIG.

This liquid crystal display element is of an active matrix type, and of a pair of transparent substrates (for example, glass substrates) 1 and 2, the lower first substrate (hereinafter, lower substrate) 1 in FIG. Transparent pixel electrode 3 and pixel electrode 3
And thin film transistors (hereinafter referred to as TFTs) 4 connected to each other are arranged in a matrix.

As shown in FIG. 2, on the lower substrate 1, gate lines (scanning lines) 5 are arranged between rows of pixel electrodes 3 and data lines (color signal lines) are arranged between columns of pixel electrodes 3.
6 is wired. The gate electrode of each TFT 4 is connected to the corresponding gate line 5, and the drain electrode is connected to the corresponding data line 6. The gate line 5 is covered with the gate insulating film (transparent film) of the TFT 4 except for the terminal portion 5a, and the data line 6 is formed on the gate insulating film. The pixel electrode 3 is formed on the gate insulating film, and one end of the pixel electrode 3 is connected to the source electrode of the TFT 4. The gate line 5 is connected to a row driver (gate driver) 21, and the data line 6 is connected to a column driver (data driver) 22.

In FIG. 1, the upper second substrate (hereinafter, referred to as
A transparent counter electrode 7 facing each pixel electrode 3 of the lower substrate 1 is formed on the upper substrate 2. The counter electrode 7 is composed of one electrode having an area over the entire display area, and a constant reference voltage is applied. A first alignment film (hereinafter, lower alignment film) 8 is provided on the electrode formation surface of the lower substrate 1. Further, a second alignment film (hereinafter, upper alignment film) 9 is provided on the electrode formation surface of the upper substrate 2. The upper and lower alignment films 9 and 8 are made of, for example, an organic polymer compound such as polyimide, and their facing surfaces are subjected to an alignment treatment by rubbing.

The lower substrate 1 and the upper substrate 2 are bonded to each other at their outer peripheral edges with a frame-shaped sealing material 10 interposed therebetween. Liquid crystal 11 is enclosed in a region surrounded by the lower substrate 1, the upper substrate 2, and the sealing material 10. The gap between the lower substrate 1 and the upper substrate 2 (more accurately, the gap between the alignment films 8 and 9 = the liquid crystal layer thickness d) is a gap material 1 arranged in a scattered state in the liquid crystal enclosing region.
It is held at a constant value by 2. A first polarizing plate (hereinafter, lower polarizing plate) 13 is arranged under the lower substrate 1, and a second polarizing plate (hereinafter, upper polarizing plate) 14 is arranged on the upper substrate 2. The optical axes of the polarizing plates 13 and 14 are set with reference to the alignment treatment direction of the alignment film 8. A reflection plate 15 is arranged below the lower polarization plate 13. In FIG. 1, reference numeral 16 indicates a liquid crystal cell.

The liquid crystal 11 is composed of, for example, a nematic liquid crystal to which a chiral liquid crystal for twist alignment is added. The product of optical anisotropy Δn of liquid crystal 11 and layer thickness d Δn ·
If d is too large, the viewing angle becomes narrow and the response speed becomes slow. Furthermore, the display color changes abruptly due to a slight change in the applied voltage, which is not preferable. If Δn · d is too small, full-color display becomes difficult. Therefore, in this embodiment, the optical anisotropy Δn of the liquid crystal 11 is 0.1.
9 to 0.25, the liquid crystal layer thickness d is 4 to 5 μm, and the product Δn · d is 0.7 μm or more and less than 1.1 μm, preferably 0.85 μm or more and less than 1.05 μm, and more preferably 0. It is set to 95 μm or more and less than 1.03 μm.

As shown in FIGS. 3B and 4B, the alignment treatment direction 9a of the upper alignment film 9 intersects the alignment treatment direction 8a of the lower alignment film 8 counterclockwise at 90 °. ing. As a result, the liquid crystal molecules are in an aligned state in which they are twisted by 90 ° from the lower substrate 1 side toward the upper substrate 2.

Further, as shown in FIGS. 3A and 4A, the transmission axis 14a of the upper polarizing plate 14 intersects the alignment treatment direction 8a of the lower alignment film 8 at 130 °. further,
As shown in FIGS. 3C and 4C, the transmission axis 13a of the lower polarizing plate 13 intersects the alignment treatment direction 8a of the lower alignment film 8 at 150 °. Therefore, the transmission axis 13a of the lower polarizing plate 13 and the transmission axis 14a of the upper polarizing plate 14 intersect at approximately 20 °.

According to the liquid crystal display device having such a structure,
By controlling the voltage applied between the pixel electrode 3 and the counter electrode 7, the alignment state of liquid crystal molecules is changed. The retardation of the liquid crystal layer also changes with the change of the alignment state of the liquid crystal molecules, and different birefringence occurs for each wavelength. Therefore, the peak wavelength of the light emitted from the upper polarizing plate 14 changes according to the change of the applied voltage, and the display color changes. That is, the display color (hue) can be controlled by controlling the applied voltage.

The change in the liquid crystal retardation is Δnd
Depends on the size of. Therefore, if Δn · d is too large, the display color changes abruptly in response to changes in applied voltage, and Δn · d
If is too small, the display color hardly changes even if the applied voltage is changed. In this embodiment, by adopting the liquid crystal 11 having Δn · d of 0.7 μm or more and less than 1.1 μm and the optical arrangement shown in FIGS. 3 and 4, it is possible to display red, green, blue, black and white. The so-called full-color display is possible. In addition, the contrast is high and the color purity is excellent. Moreover, since the twist angle of the liquid crystal molecules is as small as about 90 °, the response speed is fast and a moving image or the like can be displayed. Twisting the liquid crystal 11 by about 90 ° is possible with almost all liquid crystal materials, and the selection range of the liquid crystal material and the material of the alignment film is widened. Further, Δn · d is 0.7 μm or more and 1.1.
Since it is relatively small (less than μm), the viewing angle is wide, and it is unlikely that the display color will fluctuate due to subtle fluctuations in the thickness d of the liquid crystal layer due to manufacturing process fluctuations, fluctuations in power supply voltage, etc. Can be displayed

Specific examples and comparative examples of the liquid crystal display device based on the first embodiment will be described below. Specific Example 1 In Specific Example 1, the liquid crystal 11 is BDH manufactured by Merck & Co., Inc.
-TL205 (hereinafter referred to as liquid crystal 1) was used. The liquid crystal has an NI point of 87 ° C., Δn of 0.218, and a viscosity of 45 c.
The p and the pitch P were 69 μm. The liquid crystal layer thickness d was set to 4.63 μm, and Δn · d was set to 1.01 μm. Further, the single transmittances of the polarizing plates 13 and 14 are 44%, the polarization degree is 99.5%, and the lower polarizing plate 13 is used as the reflecting plate 15.
The bottom surface of aluminum was vapor-deposited with aluminum. Furthermore, as described above, the crossing angle between the transmission axis 14a of the upper polarizing plate 14 and the alignment treatment direction 8a of the lower alignment film 8 is 130 °, the alignment treatment direction 9a of the upper alignment film 9 and the alignment treatment of the lower alignment film 8 are performed. The intersection angle with the direction 8a was set to 90 ° (the twist angle of the liquid crystal 11 was 90 °), and the intersection angle between the transmission axis 13a of the lower polarizing plate 13 and the alignment treatment direction 8a of the lower alignment film 8 was set to 150 °.

FIG. 5 shows the relationship between the applied voltage, the reflectance and the display color in this case, and FIG. 6 shows the CIE (x, y) chromaticity diagram. As shown in FIGS. 5 and 6, the display color changed in the order of red → green → blue → black → white as the applied voltage increased, and full-color display was possible. The average response is 12
5 ms, average reflectance 13.6%, contrast 5.3
It was possible to display a bright, high-contrast color image with excellent response speed.

Concrete Example 2 In Concrete Example 2, the liquid crystal 11 is BDH manufactured by Merck & Co., Inc.
-TL215 (hereinafter referred to as liquid crystal 2) was used. The liquid crystal has an NI point of 83 ° C., Δn of 0.204, and a viscosity of 44 c.
The p and the pitch P were 73 μm. The liquid crystal layer thickness d was set to 4.63 μm, and Δn · d was set to 0.945 μm. The other configurations were the same as those in Example 1. Also in this case, the display color changes from red → green → blue → as the applied voltage rises.
It changed from black to white, and full-color display was possible. The average response is 83 ms and the average reflectance is 16.7.
%, The contrast was 7.9, and the response speed was superior to that of Example 1, and a bright and high-contrast color image could be displayed.

Concrete Example 3 As the upper and lower polarizing plates, the single transmittance is 47% and the polarization degree is 95.
%, And the other configurations were the same as those in Example 2. Also in this case, the display color changed in the order of red → green → blue → black → white with the increase of the applied voltage, and full-color display was possible. Further, the average response was 83 ms, the average reflectance was 17.4%, and the contrast was 5.4. The response speed was excellent, and bright and high-contrast color images could be displayed.

Concrete Example 4 The upper polarizing plate 14 has a single transmittance of 45% and a polarization degree of 9
The lower polarizing plate 13 is 9.5% and has a non-reflection treatment, and has a single transmittance of 47% and a polarization degree of 95%.
Other than the above, other configurations were the same as those of the specific example 2. Also in this case, the display color changed in the order of red → green → blue → black → white with the increase of the applied voltage, and full-color display was possible. The average response was 83 ms, the average reflectance was 15.8%, and the contrast was 6.3. The response speed was excellent, and bright and high-contrast color images could be displayed.

Example 5 As the reflection plate, an aluminum foil adhered to the lower surface of the lower polarizing plate 13 was used, and the other structures were the same as in Example 3.
Also in this case, the display color changed in the order of red → green → blue → black → white with the increase of the applied voltage, and full-color display was possible. The average response is 83 ms, and the average reflectance is 2
The contrast was 8.2% and the contrast was 7.0. The response speed was excellent, and a bright, high-contrast color image could be displayed.

Comparative Example 1 Unlike the arrangements shown in FIGS. 3 and 4, the crossing angle between the transmission axis 14a of the upper polarizing plate 14 and the alignment treatment direction 8a of the lower alignment film 8 is 45 °, and the alignment treatment of the upper alignment film 9 is performed. The intersection angle between the direction 9a and the alignment treatment direction 8a of the lower alignment film 8 is 90 ° (twist angle is 90 °), and the intersection angle between the transmission axis 13a of the lower polarizing plate 13 and the alignment treatment direction 8a of the lower alignment film 8 is Each was set to 45 °. That is, the structure is substantially the same as that of a normal TN liquid crystal display element. The other configurations were the same as those in Example 1. In the liquid crystal display device having this configuration, the display color changed in the order of red → green → blue → white with the increase of the applied voltage, black could not be displayed, and full color could not be displayed.

Comparative Example 2 The above-mentioned liquid crystal 1 was used as the liquid crystal 11, the liquid crystal layer thickness d was adjusted so that Δn · d was 1.13, and the other structures were the same as those of the specific example 1. In the liquid crystal display device having this structure, although it is possible to display a plurality of colors, the display colors are uneven, and the display colors are unstable with respect to the applied voltage, which makes practical full-color display difficult.

Comparative Example 3 The above liquid crystal 1 was used as the liquid crystal 11, the liquid crystal layer thickness d was adjusted so that Δn · d was 0.67, and the other structures were the same as those of the specific example 1. With the liquid crystal display device having this structure, it is difficult to display a plurality of colors, and full-color display cannot be performed.

As is clear from the above specific examples and comparative examples, according to this example, it is possible to obtain a liquid crystal display device having a high-speed response and capable of displaying a full-color image.

The present invention is not limited to this embodiment. For example, the transmission axis 14a of the upper polarizing plate 14 intersects the alignment treatment direction 8a of the lower alignment film 8 at 40 °, 13a is 15 with respect to the alignment treatment direction 8a of the lower alignment film 8.
The upper and lower polarizing plates 14 and 13 may be arranged so as to intersect at 5 °.

FIG. 7 shows changes in reflectance and display color with respect to an applied voltage when the respective optical axes are arranged in this way and the other configurations are the same as those of the concrete example 3, and the CIE thereof is shown. The chromaticity diagram is as shown in FIG. As is apparent from FIGS. 7 and 8, in this configuration, the display color changes from green → blue → red → white → black as the applied voltage increases, and a full-color image can be displayed. The average response speed is 83 ms and the contrast is 5.9, the response speed is fast and the contrast is high.

(Second Embodiment) Next, a second embodiment in which the viewing angle of the color liquid crystal display element of the first embodiment is improved will be described. FIG. 9 shows a cross-sectional structure of a liquid crystal display element according to the second embodiment, except that the first and second retardation plates 31 and 32 are arranged between the upper polarizing plate 14 and the upper substrate 2. The configuration is the same as that shown in FIG.

The first and second retardation plates 31 and 32 are made, for example, by stretching a polycarbonate resin and are biaxial with a retardation in the thickness direction. Retardation ((nx-ny) · d) is 450
The Nz coefficient value (nx-nz) / (nx-ny) in nm is about 0.2 to 0.8. Where nx is the refractive index in the direction in which the refractive index is maximum on the plane of the retardation plate, ny
Is the refractive index in the direction orthogonal to the nx direction on the plane of the retardation plate, and nz is the refractive index in the directions orthogonal to the nx direction and the ny direction. 10 (B), (C)
As shown in FIGS. 11B and 11C, in the first retardation plate 31, the stretching axis (the axis having the largest refractive index on the plane) 31 a is oriented in the alignment treatment direction 8 a of the lower alignment film 8. Against 1
The second retardation plate 32 is arranged so as to intersect at 35 °.
Indicates that the stretching axis 32a is the alignment treatment direction 8a of the lower alignment film 8.
It is placed so that it intersects at 45 °. Figure 10
(A), (C), (D) and FIGS. 11 (A), (C),
As shown in (D), the positions of the transmission axes of the upper and lower polarizing plates 14 and 13 and the twist angle of the liquid crystal are the same as in the first embodiment.

According to the liquid crystal display element having this structure, the display color changes in the order of red → green → blue → black → white as the applied voltage rises, similarly to the liquid crystal display element of the first embodiment, and a full color display is obtained. Can be displayed. Also, the response speed is fast. Further, due to the action of the phase difference plates 31 and 32, the viewing angle becomes wider than that of the liquid crystal display element of the first embodiment.

Next, a specific example of the liquid crystal display element of the second embodiment will be described. Specific Example 1 As the first and second retardation plates 31 and 32, Δn · d is 4
A 50 nm, Nz value of 0.3 was used, and other configurations were the same as those of the specific example 1 of the first embodiment. In this case, as in Example 1 of the first embodiment, the display color changed in the order of red → green → blue → black → white as the applied voltage increased, and full-color display was possible. The average response is 125m
s, the average reflectance is 14.8%, the contrast is 4.1,
Therefore, it was possible to display a bright, high-contrast image with excellent response speed. Further, the viewing angle is widened as a whole as compared with the first specific example of the first embodiment.
The viewing angle for red and green has been greatly improved.

Concrete Example 2 As the first and second retardation plates 31 and 32, Δn · d is 4
50 nm and an Nz coefficient value of 0.3 were used, and other configurations were the same as those of the concrete example 2 of the first embodiment. Also in this case, the display color changed in the order of red → green → blue → black → white with the increase of the applied voltage, and full-color display was possible. Further, the average response was 83 ms, the average reflectance was 16.5%, and the contrast was 6.1, and the response speed was excellent, and bright, high-contrast images could be displayed. Furthermore, the first
The viewing angle was widened as a whole as compared with Example 2 of the example.

As is clear from the above specific example, the second
According to the embodiment, it is possible to increase the viewing angle while ensuring the optical characteristics almost the same as those of the first embodiment.

The present invention is not limited to the above embodiment, and for example, the transmission axis 14a of the upper polarizing plate 14 intersects the alignment treatment direction 8a of the lower alignment film 8 at 40, and the first retardation plate 31 is stretched. The axis 31a is 1 with respect to the alignment treatment direction 8a of the lower alignment film 8.
35, the stretching axis 32a of the second retardation plate 32 intersects with the alignment treatment direction 8a of the lower alignment film 8 at 45, and the transmission axis 13a of the lower polarization plate 13 aligns with the alignment treatment direction of the lower alignment film 8. 8
The polarizing plates 13 and 14 and the retardation plates 31 and 32 may be arranged so as to intersect with a at 155. Also in this case,
A full-color image can be displayed and a wide viewing angle is secured.

The crossing angles shown in the first and second embodiments do not have to be exactly these values, but may be substantially these values, even if they deviate by about ± 6 °. Good. However, it is desirable to suppress the deviation by about ± 3 °. Further, the transmission axes 14a and 13 of the upper and lower polarizing plates 14 and 13 are
It is desirable that the intersection angle of a is substantially 115 ° or 20 °.

(Third Embodiment) As described above, the first embodiment
Also, according to the second embodiment, a color liquid crystal display device having a high response speed can be provided. Therefore, the liquid crystal display elements of the first and second embodiments are suitable as a liquid crystal display element for displaying a color moving image. Therefore, in the third embodiment, a moving picture display device for displaying a color moving picture using the liquid crystal display element of the above embodiment will be described with reference to FIG.

In FIG. 12, a liquid crystal display element 41 is a liquid crystal display element having the structure shown in the first or second embodiment, to which the row driver 21 and the column driver 22 shown in FIG. 2 are connected. The image memory 42 is a memory that stores image data that defines the display color of each pixel of the liquid crystal display element, and is composed of a dual port memory. A CPU (Central Processing Unit) 43 is connected to the first port of the image memory 42. The CPU 43 appropriately writes the image data of the moving image to be displayed in the image memory 42 via the first port.

A read circuit 44 is connected to the second port of the image memory 42. The read circuit 44 responds to a timing signal from a timing circuit 46 described later,
The image data is sequentially read from the image memory 42 row by row and supplied to the column driver 22. The column driver 22 responds to the timing signal from the timing circuit 46 and sequentially captures image data for one line. The column driver 22 is further generated by the drive voltage generation circuit 45,
For example, 16 levels of voltages V0 to V15 are supplied. The column driver 22 selects a voltage corresponding to the image data captured in the previous horizontal scanning period from the voltages V0 to V15 and applies it to the corresponding data line (reference numeral 6 in FIG. 2) of the liquid crystal display element 41. .

In response to the timing signal from the timing circuit 46, the row driver 21 sequentially applies a gate pulse to the gate line (reference numeral 5 in FIG. 2) of the liquid crystal display element 41, and the TFT in the corresponding row (in FIG. 2). Reference numeral 4) is turned on, and the signal on the data line is applied to the pixel electrode (reference numeral 3 in FIG. 2). The drive voltage generation circuit 45 applies voltages V0 to V applied to the pixel electrodes to display an arbitrary color.
15 and the voltage for the gate pulse is generated. The timing circuit 46 includes a read circuit 44, a row driver 21,
A timing control signal is supplied to the column driver 22.

Next, the operation of the moving picture display device having the structure shown in FIG. 12 will be described. The CPU 43 generates image data according to the image creating program, or outputs image data of a moving image supplied from the outside via the first port to the image memory 4
Write sequentially to 2. The read circuit 44 is responsive to the timing signal from the timing circuit 46 to read the image memory 42.
The image data stored in 1 is sequentially read out for each row through the second port and is supplied to the column driver 22. The column driver 22 sequentially takes in the supplied image data. In response to the timing signal, the column driver 22 applies the voltages V0 to V15 corresponding to the image data captured in the previous horizontal scanning period to the corresponding data line in each horizontal scanning period. The row driver 21 sequentially switches the gate line of the liquid crystal display element 41 and applies a gate pulse for each horizontal scanning period according to the timing signal. The TFT connected to the gate line to which the gate pulse is applied is turned on,
The voltage applied to the data line is applied to the pixel electrode via the current path of the TFT.

After that, when the gate pulse is turned off, TF
T is also turned off, the voltage applied to the pixel electrode is maintained as it is, the voltage between the pixel electrode and the counter electrode is applied to the liquid crystal until the next writing period, and a color corresponding to the applied voltage is displayed.

The liquid crystal display element 41 has the structure described in the first or second embodiment and has a high response speed, so that a moving image can be displayed in a smooth motion.

In the above embodiment, the active matrix type liquid crystal display element using the TFT (thin film transistor) as the active element has been described.
An active matrix type liquid crystal display element using M (Metal Insulator Metal) or the like as an active element,
It is also applicable to a simple matrix liquid crystal display element.

In the second embodiment, an example in which two retardation plates are arranged between the upper polarizing plate and the upper substrate has been shown. However, for example, two retardation plates are disposed between the lower polarizing plate and the lower substrate. Placed in between, or one retardation plate between the upper polarizing plate and the upper substrate,
Another one retardation plate may be arranged between the lower polarizing plate and the lower substrate. Further, in the above embodiment, the arrangement of the polarizing plates is set based on the crossing angle of the transmission axes, but the absorption axis may be set to the same angle. Which optical axis is used is arbitrary. Further, in the above embodiment, the reflection plate 15
Although the reflective liquid crystal display device having the above has been described, the present invention is also applicable to a transmissive liquid crystal display device.

[0049]

As described above, according to the liquid crystal display device of the present invention, the response speed is fast and the image can be displayed in full color. Further, by using the retardation plate, the viewing angle can be widened.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid crystal display element according to a first embodiment of the present invention.

FIG. 2 is a plan view of a substrate on which pixel electrodes and TFTs are formed.

FIG. 3 is a plan view for explaining the alignment processing direction of the vertical alignment film and the position of the transmission axis of the upper and lower polarizing plates of the liquid crystal display element according to the first embodiment of the present invention.

FIG. 4 is a perspective view for explaining the alignment processing direction of the vertical alignment film and the position of the transmission axis of the upper and lower polarizing plates of the liquid crystal display element according to the first embodiment of the present invention.

5 is a graph showing the relationship between applied voltage, reflectance and display color in Specific Example 1 of the liquid crystal display element shown in FIG.

6 is a chromaticity diagram of display colors in a specific example 1 of the liquid crystal display element shown in FIG.

7 is a graph showing the relationship between applied voltage, reflectance and display color in a modification of the liquid crystal display element shown in FIG.

8 is a chromaticity diagram of display colors in a modification of the liquid crystal display element shown in FIG.

FIG. 9 is a sectional view of a liquid crystal display element according to a second embodiment of the present invention.

FIG. 10 is a positional relationship between the alignment treatment directions of the vertical alignment films of the liquid crystal display device according to the second embodiment of the present invention, the transmission axes of the upper and lower polarizing plates, and the stretching axes of the first and second retardation plates. It is a top view for explaining.

FIG. 11 is a positional relationship between the alignment treatment directions of the vertical alignment films of the liquid crystal display element according to the second embodiment of the present invention, the transmission axes of the upper and lower polarizing plates, and the stretching axes of the first and second retardation plates. It is a perspective view for explaining.

FIG. 12 is a block diagram showing a configuration of a moving picture display device according to a third embodiment of the present invention.

[Explanation of symbols]

1 ... Lower substrate, 2 ... Upper substrate, 3 ... Pixel electrode, 4 ... TF
T (thin film transistor), 5 ... Gate line, 6 ... Data line, 7 ... Counter electrode, 8 ... Lower alignment film, 9 ... Upper alignment film, 10 ... Sealing material, 11 ... Liquid crystal, 12 ... Gap material, 13 ... Lower polarizing plate, 14 ... Upper polarizing plate, 15 ...
Reflector, 16 ... Liquid crystal cell, 21 ... Row driver, 22 ...
・ Column driver, 31 ... Retardation plate, 32 ... Retardation plate, 4
1 ... Liquid crystal display element, 42 ... Image memory, 43 ... CP
U, 44 ... Readout circuit, 45 ... Drive voltage generation circuit,
46 ... Timing circuit

Claims (8)

[Claims] 1. A first substrate and a second substrate which are arranged to face each other, a first electrode and a second electrode which are respectively formed on opposing faces of the first substrate and the second substrate, and the first electrode. And a first alignment film formed on the first substrate and subjected to an alignment treatment in a first direction, the second electrode and the second alignment film formed on the second substrate, and the first direction A second alignment film that has been subjected to an alignment treatment in a second direction substantially intersecting at 90 °, a liquid crystal that is disposed between the alignment films and is substantially 90 ° twist-aligned, A first substrate, the optical axis of which is substantially 150 ° or 155 ° with respect to the first alignment treatment direction.
And a first polarizing plate disposed so as to intersect with each other, and an optical axis of the first polarizing plate disposed outside the second substrate intersects with the first alignment treatment direction at substantially 130 ° or 40 °. And a second polarizing plate arranged as described above, and a liquid crystal display element. 2. A first and a second substrate which are arranged to face each other, a first and a second electrode which are respectively formed on opposing faces of the first and the second substrate, and the first electrode. And a first alignment film formed on the first substrate and subjected to an alignment treatment in a first direction, the second electrode and the second alignment film formed on the second substrate, and the first direction And a second alignment film that has been subjected to an alignment treatment in a second direction substantially intersecting at 90 ° with respect to the first alignment film and the second alignment film. A liquid crystal that is substantially 90 ° twist-aligned, and an optical axis of which is disposed outside the first substrate and is substantially 150 ° or 155 ° with respect to the second alignment treatment direction.
A first polarizing plate that is inclined and is arranged outside the second substrate, and its optical axis is substantially 20 ° or 1 with respect to the direction of the optical axis of the first polarizing plate.
A liquid crystal display device comprising a second polarizing plate arranged at an angle of 15 °. 3. The liquid crystal has an optical anisotropy Δn and a thickness d.
The liquid crystal display element according to claim 1 or 2, wherein the product is 0.7 μm or more and less than 1.1 μm. 4. The liquid crystal display device according to claim 1, further comprising a retardation plate for improving a viewing angle between the first and second polarizing plates. 5. The liquid crystal display element according to claim 4, wherein the retardation plate is a biaxial retardation plate having a retardation also in the thickness direction. 6. The retardation plate comprises: a first retardation plate arranged such that a direction in which the refractive index is maximum intersects the first alignment treatment direction at substantially 135 °; 6. The liquid crystal according to claim 4 or 5, further comprising: a second retardation plate arranged such that a direction in which is maximum intersects with the second alignment treatment direction at substantially 45 °. Display element. 7. A pair of substrates provided with electrodes and an alignment film and facing each other, and substantially 90 ° between the pair of substrates.
A liquid crystal cell that is encapsulated in a twist orientation and has a product of optical anisotropy Δn and its layer thickness d of 0.7 μm or more and less than 1.1 μm; The birefringence of the liquid crystal is controlled by controlling the voltage applied between the opposing electrodes, which is composed of the first and second polarizing plates whose optical axes substantially intersect at 20 ° or 115 °. A color liquid crystal display device which displays an arbitrary color. 8. A retardation plate for improving a viewing angle is provided between one of the first polarizing plate and the second polarizing plate and the liquid crystal cell, and the retardation plate is provided. Color liquid crystal display device.