JPH07294907A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the color liquid crystal display element which has a high response speed and stably displays a desired color. CONSTITUTION:Two phase difference plates 16 and 17 are arranged on a liquid crystal cell 18 and are interposed between a pair of polarizing plates 13 and 14, and a reflection plate 15 is arranged under the lower polarizing plate 13. The twist angle of liquid crystal 11 is set to 90 deg., and the upper polarizing plate 14 is so arranged that its axis of transmission crosses the direction of orientation treatment of a lower oriented film 8 at 110 to 185 deg., and the upper phase difference plate 17 is so arranged that its axis of stretching crosses the direction of orientation treatment of the lower oriented film 8 at 40 to 80 deg., and the lower phase difference plate 16 is so arranged that its axis of stretching crosses the direction of orientation treatment of the lower oriented film 8 at 130 to 160 deg., and the lower polarizing plate 13 is so arranged that its axis of transmission crosses that of the upper polarizing plate 14 at 10 to 40 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 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.
It has been disclosed that full-color display is possible by setting the thickness to 1 μm or more.

[0003]

However, in the STN type liquid crystal display device disclosed in the above publication, the response speed is slow because the twist angle of the liquid crystal molecules is as large as 180 ° to 360 °, and for example, a moving image is displayed. However, there is a problem that an insufficient frame frequency can be obtained. Further, since the twist angle of the liquid crystal is large, there is a problem that the alignment state of liquid crystal molecules is likely to be unstable. The alignment film plays a large role in stably twisting the liquid crystal molecules. For example, it is difficult to manufacture the alignment film because the pretilt angle needs to be 5 ° or more, and the material of the alignment film is limited. There is. 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 necessary to thicken the liquid crystal layer or to use a liquid crystal material having a large Δn, so that the viewing angle becomes narrow and the liquid crystal layer becomes thick. Since the applied electric field becomes weak, there is a problem that the response speed becomes slow. In addition, since Δn · d of the liquid crystal layer 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 variation in the liquid crystal layer thickness and the variation in the voltage applied to each part of the liquid crystal layer may cause The display color becomes uneven. On the other hand, it is difficult in the manufacturing process to keep the liquid crystal layer thickness constant.
Since it is difficult to eliminate subtle fluctuations in power supply voltage,
There is a problem that a desired color cannot be displayed stably. Further, there is a problem that the viewing angle is narrow.

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 display is dark because the light is attenuated by the filter.

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. First and second electrodes formed respectively on the first and second electrodes, a first alignment film formed on the first electrode and the first substrate and subjected to an alignment treatment in a first alignment treatment direction, A second alignment formed on the second electrode and the second substrate and subjected to an alignment treatment in a second alignment treatment direction that intersects the first alignment treatment direction at substantially 90 °. A film, a liquid crystal that is sealed between the first and second alignment films, and is substantially 90 ° twist-aligned, and is disposed outside the second substrate, and its transmission axis is the first axis. Substantially 140 ° to the orientation direction
A first polarizing plate arranged to intersect at ~ 160 °, and a transmission axis arranged on the outside of the first substrate.
A second polarizing plate disposed substantially intersecting the transmission axis of the second polarizing plate at 10 ° to 40 °, and disposed between the second substrate and the second polarizing plate to have a maximum refractive index. Is substantially 130 ° to the first alignment treatment direction.
A first retardation plate arranged to intersect at 160 ° and a direction in which the refractive index is maximized is arranged between the second substrate and the second polarizing plate with respect to the first alignment treatment direction. The second retardation plate is arranged so as to substantially intersect at 40 ° to 80 °.

The retardation plate is a biaxial retardation plate having a retardation also in the thickness direction. The product Δn · d of the optical anisotropy Δn of the liquid crystal and the layer thickness d is, for example, 0.7 μm or more and less than 1.1 μm.

[0009]

According to the above structure, an arbitrary display color can be obtained by controlling the alignment state of the liquid crystal molecules by the voltage applied between the opposing electrodes and controlling the birefringence of the liquid crystal. In particular, by using a liquid crystal having a product of optical anisotropy Δn and a thickness d of 0.7 or more and less than 1.1 μm, and further using a biaxial retardation plate,
Full-color display with high color purity is possible. Also, the viewing angle becomes wider. Since the twist angle of the liquid crystal molecules is as small as 90 °, and the Δn · d of the liquid crystal is as small as less than 1.1 μm, the liquid crystal layer thickness d can be made small, resulting in a high response speed
A liquid crystal display device suitable for displaying moving images can be obtained.

[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.
FIGS. 4A to 4D are plan views showing the positional relationship between the alignment treatment direction, the optical axis of the polarizing plate, and the stretching axis of the retardation plate.
(A) ~ (D) is a perspective view showing the alignment treatment direction, the optics of the polarizing plate, the optical axis of the polarizing plate and the positional relationship of the stretching axis of the retardation plate.

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. A constant reference voltage is applied to the counter electrode 7. A first alignment film (hereinafter, lower alignment film) 8 is provided on the electrode formation surface of the lower substrate 1. A second alignment film (upper alignment film) 9 is provided on the electrode formation surface of the upper substrate 2. Vertical alignment films 9 and 8
Is made of, for example, an organic polymer compound such as polyimide, and its facing surface is 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, a first retardation plate (hereinafter, lower retardation plate) 16 is arranged on the upper substrate 2, and a first retardation plate 16 is arranged thereon. Second retardation plate (hereinafter, upper retardation plate) 17
Is disposed on the second polarizing plate (hereinafter referred to as the upper polarizing plate)
14 are arranged. The polarizing plates 13 and 14 and the phase difference plate 16,
The optical axis with respect to 17 is 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 18 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 Δn · d of the optical anisotropy Δn of the liquid crystal 11 and the layer thickness d
If 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 0.19.
˜0.25, the liquid crystal layer thickness d is 4 to 5 μm, and the product Δ
n · d is 0.7 μm or more and less than 1.1 μm, preferably,
0.85 to 1.05 μm, more preferably 0.95
˜1.03 μm. The phase difference plates 16 and 17 are
For example, it is manufactured by stretching a polycarbonate resin, is composed of a biaxial retardation plate having a retardation in the thickness direction, and has an Nz coefficient value (nx-nz) / (nx-ny).
Is about 0.2 to 0.8. In addition, the phase difference plate 1
The retardations ((nx-ny) · d) of 6 and 17 are
For example, 370 nm ± 30 nm, 400 nm ± 30 n
m, 570 nm ± 30 nm and the like. 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, nz is the refractive index in the directions orthogonal to the nx direction and the ny direction, and d is the thickness.

As shown in FIGS. 3D and 4D, 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.

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 165 °. As shown in FIGS. 3 (E) and 4 (E), the transmission axis 13a of the lower polarizing plate 13
Intersects with the alignment treatment direction 8a of the lower alignment film 8 at 150 °. That is, 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 °.

As shown in FIGS. 3 (B) and 4 (B), in the upper retardation plate 17, the axis (stretching axis) 17a having the largest refractive index on the plane is in the alignment treatment direction 8a of the lower alignment film 8. 75 against
It is arranged to intersect at °. 3C and FIG.
As shown in (C), in the lower retardation plate 16, the axis (stretching axis) 16a having the largest refractive index on the plane intersects the alignment treatment direction 8a of the lower alignment film 8 at 150 ° (that is,
It is arranged so as to be parallel to the transmission axis 13a of the lower polarizing plate 13.

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 total birefringence effect of the retardation plates 16 and 17 and the liquid crystal layer changes with the change of the alignment state of the liquid crystal molecules, and the light of each wavelength has a different polarization state depending on the retardation of each wavelength. Becomes Therefore, the upper polarizing plate 14 is changed according to the change of the applied voltage.
The peak wavelength of the light emitted from the device changes, and the display color changes. That is, the display color can be controlled by controlling the birefringence by the applied voltage.

The change in the retardation of the liquid crystal 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. 90
Twisting is possible for almost all liquid crystal materials, and the range of selection of the liquid crystal material and the material of the alignment film is wide. Further, the retardation plates 16 and 17 widen the viewing angle of the liquid crystal display cell. In addition, since Δn · d is less than 1.1 μm, which is relatively small, a slight variation in the liquid crystal layer thickness d due to variations in the manufacturing process, a variation in the display color due to a variation in the power supply voltage, etc. are less likely to occur, and a desired color image can be displayed It can be displayed stably. Also, the viewing angle can be widened.

Specific examples and comparative examples of the liquid crystal display device based on the first embodiment will be described below. Example 1 As liquid crystal 11, trade name BDH-TL215 manufactured by Merck & Co., Inc.
(Hereinafter, liquid crystal 1) was used. The NI point of this liquid crystal is 8
At 3 ° C., Δn was 0.204, viscosity was 44 cp, and pitch P was 73 μm. The liquid crystal layer thickness d was set to 4.63 μm, and Δn · d was set to 0.945 μm. Further, the polarizing plates 13 and 14 had a single transmittance of 47% and a polarization degree of 95%, and the reflection plate 15 was formed by vapor-depositing aluminum on the lower surface of the lower polarizing plate 13. As the lower retardation plate 16,
The one having Δn · d of 370 nm and Nz value of 0.3 was used. As the upper retardation plate 17, Δn · d is 370 nm, N
A z value of 0.3 was used.

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 changes in the order of red → green → blue → black → white as the applied voltage increases, and full-color display is possible. Moreover, as shown in FIG. 6, the purity of each color was also excellent. Further, the average response is 83 ms and the contrast is 4.2, which is excellent in response speed and can display a color image with high contrast.

Concrete Example 2 As the liquid crystal 11, the liquid crystal 11 has a trade name BD of Merck & Co., Inc.
H-TL205 (hereinafter referred to as liquid crystal 2) 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. The other configuration was the same as that of the first specific example. Also in this case, 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 color purity was also excellent. Average response is 1
The contrast was 25 ms and the contrast was 3.8, the response speed was excellent, and a high-contrast color image could be displayed.

Comparative Example 1 The liquid crystal 1 was used as the liquid crystal 11, the thickness d of the liquid crystal layer was adjusted so that Δn · d was 1.131, and the other structures were the same as those of the specific example 1. In the liquid crystal display element with this configuration,
Although it is possible to display a plurality of colors, uneven display colors are generated, and the display colors are unstable with respect to the applied voltage, which makes practical full-color display difficult.

Comparative Example 2 The liquid crystal 1 was used as the liquid crystal 11, Δn · d was set to 0.67, and the other configurations were the same as those of the specific example 1. With the liquid crystal display device having this configuration, it is difficult to display a plurality of colors,
Full-color display was not possible.

As is clear from the above specific examples and comparative examples, according to this example, the Δn · d of the liquid crystal is 0.7 to 0.7.
1.1, a biaxial retardation plate is used as the retardation plate, and the optical arrangements shown in FIGS. 3 and 4 are adopted,
It is possible to obtain a liquid crystal display device having a high-speed response and capable of displaying a full-color image with high color purity.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The basic structure of the liquid crystal display element of this embodiment is the same as that of the liquid crystal display element of the first embodiment shown in FIGS. However, the transmission axis 14a of the upper polarizing plate 14 intersects the alignment treatment direction 8a of the lower alignment film 8 at 120 °,
The stretching axis 17a of the upper retardation plate 17 intersects the alignment treatment direction 8a of the lower alignment film 8 at 50 °, and the stretching axis 16a of the lower retardation plate 16 is 140 ° with respect to the alignment treatment direction 8a of the lower alignment film 8.
And the transmission axis 13a of the lower polarizing plate 13 intersects at a lower alignment film 8
To intersect with the alignment treatment direction 8a of
It is different from the first embodiment in that the upper and lower polarizing plates 14 and 13 and the upper and lower retardation films 17 and 16 are arranged.

As described above, the upper and lower polarizing plates 14 and 13 and the upper and lower retardation films 17 and 16 are arranged, and other configurations are the same as those of the first specific example of the first embodiment. The change in color is shown in FIG. 7, and the chromaticity diagram thereof is shown in FIG. As is clear from FIGS. 7 and 8, even in such a configuration, red, green, blue, white, and black can be displayed, and full-color display is possible. Also, the color purity of each color is high. The average response at this time is 83 ms, and the contrast is 3.
1, the response speed is fast and an image with high contrast can be displayed.

(Third Embodiment) Next, a third embodiment of the present invention will be described. The basic constitution of the liquid crystal display element of this embodiment is the same as the constitution of the liquid crystal display elements of the first and second embodiments shown in FIGS. However, the transmission axis 1 of the upper polarizing plate 14
4a intersects with the alignment treatment direction 8a of the lower alignment film 8 at 175 °, and the stretching axis 17a of the upper retardation plate 17 intersects with the alignment treatment direction 8a of the lower alignment film 8 at 75 °.
The stretching axis 16a of 6 intersects the alignment treatment direction 8a of the lower alignment film 8 at 155 °, and the transmission axis 13a of the lower polarizing plate 13 intersects the alignment treatment direction 8a of the lower alignment film 8 at 155 °. , Upper and lower polarization plates 14 and 13, upper and lower retardation plates 17 and 1
6 is different from the first and second embodiments.

In this embodiment, the upper and lower polarizing plates 14 and 13 and the upper and lower retardation films 17 and 16 are arranged in the same manner as in Embodiment 1 of the first embodiment, and the reflectance and color with respect to the applied voltage. 9 and the chromaticity diagram thereof are shown in FIG. As is clear from FIGS. 9 and 10, even in such a configuration, red, green, blue, white and black can be displayed, and full color display is possible. Also, the color purity of each color is high. The average response at this time is 83 ms, the contrast is 3.1, the response speed is fast, and an image with high contrast can be displayed.

The crossing angles of the respective axes (alignment direction, transmission axis, stretching axis) in the first to third embodiments may be substantially these values, for example, each angle is about ± 6 °. It doesn't matter if they are out of alignment. However, it is desirable to suppress the deviation by about ± 3 °.

The optical arrangements shown in the first to third embodiments are
This is the most suitable for achieving the present invention. However, the optical arrangement of the present invention is not limited to the optical arrangements of the first to third embodiments. That is, according to the present invention, the liquid crystal 11 is substantially 90 ° twist-aligned, and the transmission axis 1 of the lower polarizing plate 13 is
3a is substantially 1 with respect to the alignment treatment direction 8a of the lower alignment film 8.
The stretching axis 17a of the upper retardation plate 17 is inclined by 50 ° ± 10 °, and the stretching axis 17a of the upper retardation plate 17 is substantially inclined by 145 ° ± 15 ° with respect to the alignment treatment direction 8a of the lower alignment film 8. 16a is disposed at an angle of substantially 60 ° ± 20 ° with respect to the alignment treatment direction 8a of the lower alignment film 8, and the transmission axis 14a of the upper polarization plate 14 of the upper polarization plate 14 is aligned with the alignment treatment direction 8 of the lower alignment film 8.
It can be realized by arranging it at substantially 110 ° to 185 ° with respect to a, and the same effect can be obtained. In this case, the transmission axis 13a of the lower polarizing plate 13
The inclination angle of the transmission axis 14a of the upper polarizing plate 14 with respect to is substantially in the range of 20 ° ± 20 °. The upper and lower retardation plate 1
The positions of 7 and 16 may be interchanged.

(Fourth Embodiment) As described above, the first embodiment
According to the third embodiment, it is possible to provide a color liquid crystal display device having a high response speed. Therefore, the liquid crystal display elements of the first to third embodiments are suitable as a liquid crystal display element that displays a color moving image. Therefore, in the fourth 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. 11, a liquid crystal display element 41 is a liquid crystal display element having the structure shown in the first to third embodiments, and 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 of 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 liquid crystal display device having the structure shown in FIG. 11 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 is displayed according to the applied voltage.

The liquid crystal display element 41 has the structure described in the first to fourth embodiments and has a high response speed, so that a moving image can be displayed with 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. Further, in the above-mentioned embodiment, the reflective liquid crystal display element provided with the reflection plate 15 has been described, but the present invention is also applicable to a transmissive liquid crystal display element.

[0041]

As described above, according to the liquid crystal display device of the present invention, the response speed is fast and a full color image can be displayed. 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 treatment direction of the upper and lower alignment films, the position of the transmission axis of the upper and lower polarizing plates, and the position of the stretching axis of the retardation plate.

FIG. 4 is a perspective view for explaining the alignment treatment direction of the upper and lower alignment films, the positions of the transmission axes of the upper and lower polarizing plates, and the position of the stretching axis of the retardation plate.

FIG. 5 is a graph showing the relationship between applied voltage, reflectance and display color in the liquid crystal display element according to the first example of the present invention.

FIG. 6 is a chromaticity diagram of display colors of the liquid crystal display element according to the first example.

FIG. 7 is a graph showing the relationship between the applied voltage, the reflectance, and the display color in the liquid crystal display element according to the second embodiment of the present invention.

FIG. 8 is a chromaticity diagram of display colors of the liquid crystal display element according to the second example.

FIG. 9 is a graph showing a relationship between an applied voltage, a reflectance and a display color in the liquid crystal display element according to the third embodiment of the present invention.

FIG. 10 is a chromaticity diagram of display colors of the liquid crystal display element according to the third example.

FIG. 11 is a block diagram showing a configuration of a moving image display device according to a fourth example of the present invention.

[Explanation of symbols]

1 ... Lower substrate, 2 ... Upper substrate, 3 ... Pixel electrode, 4 ... Thin film transistor (TFT), 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 Polarizer, 15 ...
Reflector, 16 ... Lower retardation plate, 17 ... Upper retardation plate, 18
... Liquid crystal cell, 21 ... Row driver, 22 ... Column driver, 41 ... Liquid crystal display element, 42 ... Image memory, 43 ...
・ CPU, 44 ... Readout circuit, 45 ... Drive voltage generation circuit

Claims (6)

[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. A first alignment film formed on the first substrate and subjected to an alignment treatment in a first alignment treatment direction; formed on the second electrode and the second substrate; Second which intersects substantially 90 ° with the orientation treatment direction of
And a second alignment film that has been subjected to an alignment treatment in the alignment treatment direction, and is sealed between the first and second alignment films, and is substantially 90
A twisted liquid crystal and a first liquid crystal disposed outside the second substrate, the transmission axis of which intersects with the first alignment treatment direction at substantially 140 ° to 160 °. A polarizing plate and a second polarizing plate disposed outside the first substrate, the transmission axis of which intersects the transmission axis of the first polarizing plate at substantially 10 ° to 40 °. And disposed between the second substrate and the second polarizing plate such that the direction in which the refractive index is maximum intersects the first alignment treatment direction substantially at 130 ° to 160 °. The first retardation plate is disposed between the second substrate and the second polarizing plate, and the direction in which the refractive index is maximized is substantially 40 ° to 80 ° with respect to the first alignment treatment direction. A color liquid crystal display characterized by comprising a second retardation plate arranged to intersect with each other. 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. A first alignment film formed on the first substrate and subjected to an alignment treatment in a first alignment treatment direction; formed on the second electrode and the second substrate; Second which intersects substantially 90 ° with the orientation treatment direction of
And a second alignment film that has been subjected to an alignment treatment in the alignment treatment direction, and is sealed between the first and second alignment films, and is substantially 90
A twist-aligned liquid crystal, and a first polarizing plate disposed outside the first substrate, the transmission axis of which intersects the first alignment treatment direction at substantially 150 °. A second polarizing plate disposed outside the second substrate, the transmission axis of which crosses the first alignment treatment direction at substantially 165 °, and the second substrate. A first retardation plate disposed between the second polarizing plates, the first retardation plate being disposed such that a direction having a maximum refractive index intersects the first alignment treatment direction at substantially 150 °; A second retardation plate which is arranged between the substrate and the second polarizing plate, and which is arranged such that the direction in which the refractive index is maximum intersects the first alignment treatment direction at substantially 75 °. A color liquid crystal display device comprising: 3. 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. A first alignment film formed on the first substrate and subjected to an alignment treatment in a first alignment treatment direction; formed on the second electrode and the second substrate; The second intersecting with the alignment treatment direction of
And a second alignment film that has been subjected to an alignment treatment in the alignment treatment direction, and is sealed between the first and second alignment films, and is substantially 90
A twist-aligned liquid crystal, and a first polarizing plate disposed outside the first substrate, the transmission axis of which intersects the first alignment treatment direction at substantially 150 °. A second polarizing plate disposed outside the second substrate, the transmission axis of which intersects the first alignment treatment direction at substantially 120 °, and the second substrate. A first retardation plate disposed between the second polarizing plates, the first retardation plate being disposed such that a direction having a maximum refractive index intersects the first alignment treatment direction at substantially 140 °; A second retardation plate which is arranged between the substrate and the second polarizing plate, and is arranged such that the direction in which the refractive index is maximum intersects the first alignment treatment direction at substantially 50 °. A color liquid crystal display device comprising: 4. 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. A first alignment film formed on the first substrate and subjected to an alignment treatment in a first alignment treatment direction; formed on the second electrode and the second substrate; And a second alignment film that has been subjected to an alignment treatment in a second alignment treatment direction substantially intersecting the alignment treatment direction of 90 °, and is sealed between the first and second alignment films. , Substantially 90
° twist-aligned liquid crystal, and a first polarizing plate disposed outside the first substrate and having a transmission axis thereof intersecting substantially 155 ° with the first alignment treatment direction. A second polarizing plate disposed outside the second substrate, the transmission axis of which crosses the first alignment treatment direction at substantially 175 °, and the second substrate. A first retardation plate disposed between the second polarizing plates, the first retardation plate being disposed such that a direction having a maximum refractive index intersects with the first alignment treatment direction by substantially 155 °; A second retardation plate which is arranged between the substrate and the second polarizing plate, and which is arranged such that the direction in which the refractive index is maximum intersects the first alignment treatment direction at substantially 75 °. A color liquid crystal display device comprising: 5. The first and second retardation plates are biaxial retardation plates having a retardation in a plane direction and a thickness direction, according to any one of claims 1 to 4. The color liquid crystal display device described in 1. 6. The product Δ of the optical anisotropy Δn of the liquid crystal and the layer thickness d.
6. The color liquid crystal display element according to claim 1, wherein n · d is 0.7 μm or more and less than 1.1 μm.