JPH07294900A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display element which is fast in response speed and can display a full-color image of high color purity. CONSTITUTION:A couple of substrates 1 and 2 on which orientation films are formed are arranged in opposite to each other and liquid crystal 11 is charged between them to form a liquid crystal cell 17. The DELTAn.n of the liquid crystal 11 is 0.7-1.1mum. The orientation processing direction of one orientation film 8 and the orientation processing direction of the other orientation film 9 cross each other at 90 deg. and liquid crystal molecules are twisted and oriented at 90 deg.. A couple of polarizing plates 13 and 14 are arranged across the liquid crystal cell 17, the axis of transmission of one polarizing plate 13 crosses the orientation processing direction of one orientation film 8 at 140 deg., and the axis of transmission of the other polarizing plate 14 crosses the orientation processing direction of one orientation film 8 at 70 deg.. A phase difference plate 16 is arranged between the other substrate 2 and the other polarizing plate 14, and the axis of elongation crosses the orientation processing direction of one orientation film 8 at 70 deg.. The phase difference plate 16 is a two-axial phase difference plate whose Nz value is 0.3.

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. This STN liquid crystal display element can display substantially two colors of black and yellow, or blue and white. Japanese Patent Laid-Open No. 2-201422 discloses a nematic liquid crystal molecule having a twist angle of 180 ° as a multicolor display using such an STN type liquid crystal display element.
To 360 °, and Δn · d of the liquid crystal layer is 1.1μ.
An STN type liquid crystal display device capable of full color display by setting the thickness to m or more is disclosed.

[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 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 is set to 5 ° or more, and the manufacturing of the alignment film becomes difficult. further,
Liquid crystals with a large elastic constant ratio K33 / K11 are difficult to align, so liquid crystals with a small elastic constant ratio must be selected.
There is a problem that the range of liquid crystal selection becomes narrow.

Further, since the liquid crystal layer has a large Δn · d, it is necessary to thicken the liquid crystal layer or use a liquid crystal material having a large Δn, which narrows the viewing angle and thickens the liquid crystal layer. Since the electric field strength is weakened accordingly, there is a problem that the response speed becomes slow. Further, since Δn · 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 is changed due to the variation in the liquid crystal layer thickness or the variation in the voltage applied to each part of the liquid crystal layer. It causes unevenness. 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 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 first substrate, and its transmission axis is the first axis. Substantially 140 ° to the orientation direction
The first polarizing plates arranged so as to intersect each other at ˜165 ° and the direction in which the refractive index is maximized, which is arranged outside the second substrate, is substantially 130 with respect to the first alignment treatment direction.
And a retardation plate disposed to intersect at 60 ° to 80 ° and a transmission axis disposed outside the retardation plate, the transmission axis of which is substantially the same as the transmission axis of the first polarizing plate. 10 °
It is characterized in that it is composed of a second polarizing plate arranged to intersect each other at -20 °. The product Δn · d of the optical anisotropy Δn of the liquid crystal and the layer thickness d is, for example, 0.7 μm.
The above is less than 1.1 μm.

[0008]

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 in which the product of the optical anisotropy Δn and the thickness d is 0.7 or more and less than 1.1 μm, full-color display with high color purity can be performed.
The twist angle of the liquid crystal molecules is as small as 90 °, the Δn · d of the liquid crystal is as small as less than 1.1 μm, and the liquid crystal layer thickness d can be made small. The device is obtained.

[0009]

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. FIG. 1 is a sectional view of the liquid crystal display device of this embodiment, FIG. 2 is a plan view of a substrate on which pixel electrodes and TFTs (thin film transistors) are formed, and FIGS. A plan view showing the positional relationship between the axis and the stretching axis of the retardation plate,
4 (A) to 4 (D) are perspective views showing the positional relationship between the alignment treatment direction, the optics of the polarizing plate, the optical axis of the polarizing plate, and the direction in which the refractive index of the retardation plate is maximum (stretching axis). is there.

This liquid crystal display device is of an active matrix type, and of a pair of transparent substrates (eg, glass substrates) 1 and 2, the first substrate (hereinafter, lower substrate) 1 on the lower side in FIG. Transparent pixel electrode 3 and pixel electrode 3
And thin film transistors (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 the rows of the pixel electrodes 3, and data lines (color signal lines) are arranged between the columns of the 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, a second upper 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 adhered to each other at their outer peripheral edges via a frame-shaped 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 set to a constant value by the gap material 12 arranged in a scattered state in the liquid crystal enclosing region. Retained.

A liquid crystal 11 is enclosed in a region surrounded by the lower substrate 1, the upper substrate 2 and the sealing material 10. The liquid crystal 11 is
For example, it is made of a nematic liquid crystal to which a chiral liquid crystal 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 to 1.05 μm, and more preferably 0. It is set to 95 μm to 1.03 μm.

Under the lower substrate 1, a first polarizing plate (hereinafter, lower polarizing plate) 13 is arranged. Phase difference plate 16 on the upper substrate 2
Are placed. The retardation plate 16 is produced, for example, by stretching a polycarbonate resin, is composed of a biaxial retardation plate having a retardation in the thickness direction, and has a retardation ((nx-ny) · d) of For example, 370 nm ±
30 nm, Nz coefficient value (nx-nz) / (nx-ny)
Is 0.2 to 0.8. Here, 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 direction of nx on the plane of the retardation plate, and nz is the direction of nx and The refractive index in the direction orthogonal to the ny direction is shown. A second polarizing plate (hereinafter, upper polarizing plate) 14 is arranged on the retardation plate 16. The optical axes of the upper and lower polarizing plates 14 and 13 and the retardation plate 16 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 17 indicates a liquid crystal cell.

As shown in FIGS. 3C and 4C, 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 with the alignment treatment direction 8a of the lower alignment film 8 at 170 °. As shown in FIGS. 3D and 4D, the transmission axis 13 a 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 °.

The retardation plate 16 has its stretching axis 16a (the axis having the largest refractive index on the plane) 16a intersecting the alignment treatment direction 8a of the lower alignment film 8 at 150 ° (that is, the lower polarizing plate 13). Is arranged so as to be parallel to the transmission axis 13a.

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. Along with the change in the alignment state of the liquid crystal molecules, the synthetic retardation of the liquid crystal layer and the retardation plate 16 also changes, and different birefringence occurs for each wavelength. Therefore, the upper polarizing plate 1 may be changed according to the change of the applied voltage.
The peak wavelength of the light emitted from 4 changes, and the display color changes. That is, the display color (hue) can be controlled by controlling the voltage applied between the pixel electrode 3 and the counter electrode 7. The change in the retardation of the liquid crystal depends on the magnitude of Δn · d. Therefore, if Δn · d is too large, the display color changes rapidly with respect to the change in applied voltage, and if Δn · d is too small, the display color hardly changes even if the applied voltage is changed.

In the present embodiment, by adopting the liquid crystal 11 having Δn · d of 0.7 μm or more and less than 1.1 μm, the biaxial phase plate 16, and the optical arrangement shown in FIGS. 3 and 4, red,
Green, blue, black, and white can be displayed, and so-called full-color display can be performed. In addition, the contrast is high and the color purity is excellent.

Further, 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 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 wide. Further, since Δn · d is 0.7 μm or more and 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 display color due to a variation in power supply voltage, and the like are less likely to occur. The color image of can be displayed stably. Also, the viewing angle can be widened.

Specific examples and comparative examples of the liquid crystal display element 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. Polarizing plate 1
The unit transmittance of 3 and 14 is 47%, the polarization degree is 95%,
As the reflecting plate 15, a lower polarizing plate 13 having a lower surface on which aluminum was vapor-deposited was used. As the retardation plate 16, one having a retardation ((nx-ny) · d) of 370 nm and an Nz coefficient value of 0.3 was used. Furthermore, the upper polarizing plate 14
Of the transmission axis 14a of the lower alignment film 8 and the alignment treatment direction 8a of the lower alignment film 8 is 170 °, and the intersection angle of the alignment treatment direction 9a of the upper alignment film 9 and the alignment treatment direction 8a of the lower alignment film 8 is 90 ° (liquid crystal 11 has a twist angle of 90 °, the crossing 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 150 °, the transmission axis 16a of the retardation plate 16 and the alignment of the lower alignment film 8 The angle of intersection with the processing direction 8a 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 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 The liquid crystal 11 has a trade name BDH-TL205 manufactured by Merck & Co., Inc.
(Hereinafter, liquid crystal 2) was used. The NI point of this liquid crystal is 8
At 7 ° C., Δn was 0.218, viscosity was 45 cp, and pitch P was 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 configurations were the same as those in Example 1. 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. The average response was 125 ms and the contrast was 3.8, which was inferior to that of Example 1, but was excellent in response speed and a color image with high contrast could be displayed.

Comparative Example 1 Different from the arrangement shown in FIG.
Between the lower substrate 1 and the lower substrate 1, and the transmission axis 14a of the upper polarizing plate 14
And the crossing angle of the alignment treatment direction 8a of the lower alignment film 8 is 170
The crossing 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 150 °, and the crossing angle between the transmission axis 16a of the retardation plate 16 and the alignment treatment direction 8a of the lower alignment film 8 Were set to 170 °. The other configurations are the same as those of the first specific example. In the liquid crystal display device having this structure, the display color changed from dark red to dark green to light green with an increase in applied voltage, and color display was not possible.

Comparative Example 2 The liquid crystal 2 was used as the liquid crystal 11, and the liquid crystal layer thickness d was adjusted so that Δn · d was 1.13.
It has the same configuration as. In the liquid crystal display device having this configuration, although a plurality of colors can be displayed, the display colors are uneven and the display colors are unstable with respect to the applied voltage, making it difficult to perform a practical full-color display.

Comparative Example 3 The above-mentioned 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 structure, full-color display was not possible.

As is clear from the above specific examples, according to this example, a liquid crystal having Δn · d of 0.7 μm or more and less than 1.1 μm is used, and further shown in FIGS. Since it uses an optical arrangement, it has high-speed response.
A liquid crystal display device capable of displaying a full-color image with high color purity can be obtained. Further, since the biaxial retardation plate is used, the viewing angle is also improved.

(Second Embodiment) Next, a color liquid crystal display device according to 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 is the alignment treatment direction 8a of the lower alignment film 8.
Crosses at 140 ° with respect to the transmission axis 13a of the lower polarizing plate 13.
Crosses the alignment treatment direction 8a of the lower alignment film 8 at 155 °, and the stretching axis 16a of the retardation plate 16 intersects the alignment treatment direction 8a of the lower alignment film 8 at 70 °. , 13 and the phase difference plate 16 are arranged.

Orientation processing directions 8a and 9a, transmission axis 13
a, 14a, and the stretching axis 16a are arranged as described above, the liquid crystal 11 described above is used as the liquid crystal 11, and the reflectance with respect to the applied voltage when other configurations are the same as those of the specific example 1 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 was 83 ms and the contrast was 5.4.
Therefore, it is possible to display an image with high response speed and high contrast.

(Third Embodiment) Next, a color liquid crystal display device according to a third 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 is the alignment treatment direction 8a of the lower alignment film 8.
Crosses at 130 ° with respect to the transmission axis 13a of the lower polarizing plate 13.
Crosses the alignment treatment direction 8a of the lower alignment film 8 at 150 °, and the stretching axis 16a of the retardation plate 16 intersects the alignment treatment direction 8a of the lower alignment film 8 at 140 °. , 13 and the retardation plate 16 are arranged, and the retardation value of the retardation plate 16 is 570 nm.

Orientation processing directions 8a and 9a, transmission axis 13
a, 14a, and the stretching axis 16a are arranged as described above, the liquid crystal 11 described above is used as the liquid crystal 11, and the reflectance with respect to the applied voltage when other configurations are the same as those of the specific example 1 of the first embodiment. The change in color is shown in FIG. 9, and the chromaticity diagram thereof is shown in FIG. As is clear from FIGS. 9 and 10, even in this configuration, red, green, blue, white, and black with high color purity can be displayed,
Full color display is possible. Furthermore, the average response at this time is 83 ms, the contrast is 3.2, and the response speed is fast and an image with high contrast can be displayed.

The crossing angles of the alignment treatment directions 8a and 9a, the transmission axes 13a and 14a, and the stretching axis 16a shown in the first to third embodiments do not need to be exactly these values, but these values are substantially the same. Any value will do. For example, each intersection angle is ± 6 °
It does not matter if they are slightly different. However, it is desirable to suppress the deviation by about ± 3 °.

The arrangements of the alignment treatment directions 8a and 9a, the transmission axes 13a and 14a, and the stretching axis 16a shown in the first to third embodiments are the most suitable for achieving the present invention.
However, the present invention is not limited to 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 13a of the lower polarizing plate 13 is
Is substantially 140 with respect to the alignment treatment direction 8a of the lower alignment film 8.
Are arranged so as to intersect with each other at an angle of from ° to 165 °, and the stretching axis 16a of the retardation plate 16 substantially intersects with the alignment treatment direction 8a of the lower alignment film 8 at an angle of from 130 ° to 160 ° or from 60 ° to 80 °. However, the transmission axis 14a of the upper polarizing plate 14 and the transmission axis 13a of the lower polarizing plate 13 may be disposed so as to intersect each other at substantially 10 ° to 20 °, and a desired effect can be obtained.

(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 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. 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.

Since the liquid crystal display element 41 has the structure described in the first embodiment and has a high response speed, it can display a moving image with a smooth motion.

In the above embodiments, 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 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-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.

[0043]

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 and the positions of the transmission axes of the upper and lower polarizing plates.

FIG. 4 is a perspective view for explaining the alignment treatment direction of the upper and lower alignment films and the positions of the transmission axes of the upper and lower polarizing plates.

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 second 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 ... Retardation plate, 17 ... Liquid crystal cell, 21 ...
Row driver, 22 ... Column driver, 41 ... Liquid crystal display element, 42 ... Image memory, 43 ... CPU, 44 ... Read circuit, 45 ... Drive voltage generation circuit, 46 ...・ Timing 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 display disposed outside the first substrate, the transmission axis of which crosses the first alignment treatment direction at substantially 140 ° to 165 °. The polarizing plate is disposed outside the second substrate, and the direction in which the refractive index is maximum is substantially 13 with respect to the first alignment treatment direction.
A retardation plate arranged so as to intersect at 0 ° to 160 ° or 60 ° to 80 °, and a transmission axis disposed outside the retardation plate, the transmission axis of which is the first
And a second polarizing plate arranged so as to substantially intersect with the transmission axis of the polarizing plate at 10 ° to 20 °. 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 °. Is disposed outside the second substrate, and the direction in which the refractive index is maximum is substantially 15 with respect to the first alignment treatment direction.
A retardation plate disposed so as to intersect at 0 °, and a transmission axis disposed outside the retardation plate and having the transmission axis of the first retardation plate.
2. A liquid crystal display device, comprising: a second polarizing plate disposed so as to substantially intersect with the alignment treatment direction at 170 °. 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; 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
° 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. Is disposed outside the second substrate, and the direction in which the refractive index is maximum is substantially 70 with respect to the first alignment treatment direction.
And a retardation plate that is disposed outside the retardation plate and that has a transmission axis that is the first transmission axis.
2. A liquid crystal display device, comprising: a second polarizing plate disposed so as to substantially intersect with the alignment treatment direction of 140 °. 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; 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 °. Is disposed outside the second substrate, and the direction having the largest refractive index is substantially 14 with respect to the first alignment treatment direction.
A retardation plate disposed so as to intersect at 0 °, and a transmission axis disposed outside the retardation plate and having the transmission axis of the first retardation plate.
2. A liquid crystal display device, comprising: a second polarizing plate arranged so as to substantially intersect with the alignment treatment direction at 130 °. 5. The product Δ of the optical anisotropy Δn of the liquid crystal and the layer thickness d.
5. The liquid crystal display element according to claim 1, wherein n · d is 0.7 μm or more and less than 1.1 μm. 6. The liquid crystal display element according to claim 1, wherein the retardation plate is a biaxial retardation plate having a retardation also in the thickness direction.