JP2856188B2 - Active matrix liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display panel which can be easily manufactured, has a wide view angle and a high speed response, and causes hard to generate gradation reversal. SOLUTION: A picture element electrode 3 is formed on one glass substrate 6, and a counter electrode 2 is formed on the other glass substrate 6. A liquid crystal layer having a positive dielectric anisotropy in provided between both substrates 6. The counter electrode 2 and the picture electrode 3 are not regularly located but alternately located. A polarizing light boards 4 and 10 are arranged outside of both substrates 2, an optical compensation layer 5 having a negative single axis refractive index anisotropy is inserted between the polarizing plate 4 and the glass substrate 6, and the anisotropy axis is vertical to the substrate 2. When an electric field is diagonally impressed between both electrodes 2 and 3, the liquid crystal molecules in the sections A, B fall in the opposite directions, and white is displayed with a wide field of view. When no voltage is impressed, retardation by the liquid crystal is compensated by the optical compensation layer 5 and stable black is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix liquid crystal display panel having a structure in which a liquid crystal is sandwiched between transparent substrates.

[0002]

2. Description of the Related Art An active matrix liquid crystal display panel using a thin film field effect transistor (hereinafter, referred to as "TFT") as a switching element (active element) of a pixel can provide high-quality image quality. Or recently, it has been widely used as a monitor for a space-saving desktop computer.

A liquid crystal display panel of a twisted nematic mode (hereinafter referred to as "TN"), which has been generally used in the past, uses a liquid crystal having a positive dielectric anisotropy so that liquid crystal molecules are twisted by 90 degrees between both substrates. Is subjected to an orientation treatment. Then, when an electric field is applied, the liquid crystal molecules rise three-dimensionally from the liquid crystal layer surface, cancel the twist and become perpendicular to both substrates, thereby controlling transmitted light.

In recent years, a so-called in-plane switching mode (hereinafter referred to as “IPS”) using a lateral electric field has been proposed to improve the viewing angle characteristics in order to further improve the image quality of a liquid crystal display. An adopted active matrix liquid crystal display panel has been proposed. An example of this was announced at “Asia Display '95” held October 16-18, 1995, and the paper “Principles and Characteristics
f Electro-Optical Behavior with In-Plane Switchin
g Mode ". In this liquid crystal display panel, as shown in FIG. 11, a liquid crystal layer having a positive dielectric anisotropy is formed on one of a pair of substrates 30 by forming a linear pixel electrode 31 and a counter electrode 32 parallel to each other. In this configuration, no electrode is formed on the other substrate. A polarizing plate 33 is provided outside each of the two substrates, and both polarizing plates 30 are provided.
Are orthogonal to each other. That is,
Both polarizing plates 30 are in a crossed Nicols positional relationship. When a voltage is applied between the pixel electrode 31 and the counter electrode 32 to generate a parallel horizontal electric field in the liquid crystal layer plane, the direction of the director of the liquid crystal molecules 36 is changed, thereby controlling the transmitted light. Things.

Further, a liquid crystal display panel having a configuration in which liquid crystals are vertically aligned has been proposed. In one example, as shown in FIG. 12, a liquid crystal layer 37 having a negative dielectric anisotropy is formed between a pair of substrates 38. Then, an electric field 46 perpendicular to the substrate 38 is applied between the transparent electrodes 39 and 40 formed on the inner surfaces of both substrates 38, respectively, so that the liquid crystal molecules 41 are tilted and transmitted light is controlled. The transparent electrode 3
Alignment films 42 are formed inside 9 and 40, respectively, and the liquid crystal is aligned so as to be perpendicular to the substrate surface in the state where no voltage is applied. The polarizers 4 are provided on the outside of the substrate 38, respectively.
3 are provided.

Another example is disclosed in JP-A-56-88179. In this configuration, a linear counter electrode and a pixel electrode that are parallel to each other are formed on separate substrates, and the two electrodes are arranged so as not to be at the opposing positions but to be staggered. Then, an electric field in an oblique direction that is neither parallel nor perpendicular to the substrate is applied.

[0007]

The above four types of conventional active matrix liquid crystal display systems have the following problems which are unique to each of them.

In the case of the TN mode liquid crystal display panel, the liquid crystal molecules rise three-dimensionally from the surface of the liquid crystal layer. Therefore, when viewed from the direction parallel to the director of the raised liquid crystal molecules, and from the normal direction of the liquid crystal layer. The appearance changes when you look at it. Then, when the liquid crystal display panel is viewed from an oblique direction, there is a problem that the relationship between the applied voltage and the transmittance greatly differs. Specifically, as shown in FIG. 13, the voltage-transmittance characteristics of a TN mode liquid crystal display panel viewed from the front show that the transmittance becomes lower as the applied voltage increases from about 2V. While it is a monotonous decreasing curve, when viewed obliquely,
The transmittance temporarily decreases with an increase in the applied voltage, becomes zero at a voltage of about 2 V, then increases again as the voltage increases, and decreases when the voltage exceeds 3 V. Thus, it becomes a complicated curve with extreme values. Therefore, when the drive voltage is set based on the voltage-transmittance characteristic when viewed from the front, when the display is viewed from an oblique direction, the grayscale inversion occurs such that the white display portion becomes black or the black display portion becomes whitish. May occur. As a result, the display is normally visually recognized and usable only within a viewing angle range of about 40 degrees left, right, 15 degrees, and 5 degrees below the TN mode liquid crystal display panel. Of course, the up, down, left, and right directions can be changed depending on the method of installing the liquid crystal display panel.

On the other hand, in the case of the IPS mode shown in FIG. 11, the liquid crystal molecules 36 move only in the direction substantially parallel to the liquid crystal layer surface (two-dimensionally). There is an advantage that almost similar images can be obtained. Specifically, it can be used in a range of a viewing angle of about 40 degrees up, down, left, and right. However, the IPS method mainly uses the twist deformation of the liquid crystal to control transmitted light, and this twist deformation has a considerably slower response speed than other deformation modes (bend deformation, splay deformation, etc.), There is a problem that the image when is displayed is not very good.

The structure in which the liquid crystal having negative dielectric anisotropy shown in FIG. 12 is vertically aligned is oblique from the direction in which the liquid crystal falls, that is, from the direction parallel to the director of the liquid crystal molecules 41 that fall. When viewed, there is a possibility that so-called gradation inversion in which white display and black display are reversed may occur. In order to prevent this, the direction in which the liquid crystal molecules 41 fall is not made uniform, and is divided into a section 44 in which the liquid crystal molecules fall in one direction and a section 45 in which the liquid crystal molecules fall in a different direction (a direction symmetric to the one direction, etc.). There is a liquid crystal display panel. However, such a division requires a special process such as orientation division, which has resulted in an increase in the number of manufacturing steps and an increase in complexity. Further, in order to defeat the liquid crystal oriented perpendicular to the substrate surface by applying an electric field 46 perpendicular to the substrate surface, it is necessary to use a liquid crystal having a negative dielectric anisotropy. But,
Liquid crystal materials having negative dielectric anisotropy are limited, and there are few suitable liquid crystal materials satisfying conditions such as reliability and operating temperature range, and there is a problem that the degree of freedom in material selection is low.

The configuration disclosed in Japanese Patent Application Laid-Open No. 56-88179 solves the problem of the configuration shown in FIG. 13. When no electric field is applied, the liquid crystal molecules are perpendicular to the substrate. The directions of the axes are all perpendicular to the substrate, the transmittance for vertically incident light is almost 0, and black display is performed. However, with respect to the incident light from the oblique direction, the light passing through the incident-side polarizing plate becomes elliptically polarized in the liquid crystal layer, and cannot be absorbed by the emitting-side polarizing plate, resulting in a whitish display. Thus, there is a problem that gradation inversion occurs due to retardation in the liquid crystal layer.

As described above, the conventional active matrix liquid crystal display panel has problems of viewing angle, response speed, manufacturing process, liquid crystal material, gradation inversion, and the like.
Each display method has its own problems.

It is an object of the present invention to provide a wide viewing angle, a high response speed, and a simple process.
An object of the present invention is to provide an active matrix liquid crystal display panel in which gradation inversion hardly occurs.

[0014]

In order to achieve the above-mentioned object, the present invention provides a plurality of transparent insulating substrates provided on one of a pair of transparent insulating substrates so as to intersect each other and form a lattice. Scanning lines and a plurality of signal lines, a plurality of active elements provided near each intersection of the scanning lines and the signal lines, and a plurality of parallel linear pixel electrodes connected to the active elements. The other transparent insulating substrate is provided with a plurality of parallel linear opposing electrodes provided corresponding to each pixel electrode and applied with a voltage between the pixel electrode and the transparent insulating substrate. In an active matrix liquid crystal display panel in which a liquid crystal layer is provided between the substrates and a polarizing plate is provided outside each of the transparent insulating substrates, the pixel electrode and the counter electrode face each other. Avoid and arrange to be staggered The liquid crystal layer has a positive dielectric anisotropy, and the director of the liquid crystal molecules is substantially perpendicular to the transparent insulating substrate when the voltage between the pixel electrode and the counter electrode is zero. The optical compensation layer having a negative uniaxial refractive index anisotropy is disposed between at least one transparent insulating substrate and the polarizing plate, and the direction of the anisotropic axis of the optical compensation layer is It is substantially perpendicular to the transparent insulating substrate. With such a configuration, the liquid crystal display panel can be easily divided into a plurality of sections in which liquid crystal molecules fall in different directions when a voltage is applied. The effect of retardation can be canceled.

The optical compensation layer may have a multilayer structure, and a plurality of layers having a uniaxial refractive index anisotropy may be superposed to have a substantially negative uniaxial refractive index anisotropy.

The polarization axes of both polarizers are orthogonal to each other, and the angles formed by the longitudinal directions of the pixel electrode and the counter electrode are each 45 degrees.
It is also possible to adopt a configuration having a certain degree.

Further, a configuration may be employed in which a color filter is provided on the transparent insulating substrate on which the counter electrode is formed, and the counter electrode and the black matrix are formed in the same layer.

Preferably, the counter electrode and the black matrix are located closer to the liquid crystal layer than the color filters.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the active matrix liquid crystal display panel of the present invention, and FIG. 2 is a plan view showing only a main part in a simplified manner. First, the active matrix substrate X (incident side in this embodiment) will be described. A scanning line 14 is formed on a glass substrate (transparent insulating substrate) 6, and a gate insulating film 9 is formed so as to cover the scanning line 14.
Are formed. Furthermore, an island-shaped amorphous silicon 13 forming a part of a thin film transistor (hereinafter, referred to as a “TFT”) as an active element, and a pixel electrode 3 forming a pixel are further provided thereon.
And the signal line 1 are formed, and each pixel electrode 3 and the signal line 1 are parallel to each other. Then, a protective insulating film 8 and an alignment film 11 are formed by lamination. The source electrode of the TFT is connected to the pixel electrode 3, the drain electrode is connected to the signal line 1, and the scanning line 14 is the gate electrode of the TFT. Then, a portion of the two adjacent scanning lines 14 where the scanning line that does not drive the TFT overlaps the pixel electrode 3 is the storage capacitor 12.

On the color filter substrate Y (in the present embodiment, the emission side), a color layer 18 forming a color filter is provided on one surface of a glass substrate (transparent insulating substrate) 6, and the pixel electrode 3 is formed thereon. And a grid-like black matrix 15 are formed. A constant potential is externally supplied to the counter electrode 2 via the black matrix 15. Further, the same alignment film 20 as that on the active matrix substrate side is further provided thereon. The details of the manufacturing method will be described later.

The active matrix substrate X and the color filter substrate Y are arranged so that the alignment films face each other, and the liquid crystal layer 7 is provided between the alignment films 11 and 20 of both substrates.
Is provided. The liquid crystal material has a positive dielectric anisotropy and is aligned substantially perpendicular to the substrate by both alignment films 11 and 20.

The opposing electrode 2 and the pixel electrode 3 are not at positions facing each other, but are arranged alternately. Polarizing plates 4 and 10 are provided outside the two glass substrates 6, and the polarizing axis directions 16 and 17 of the polarizing plates are set to be perpendicular to each other and at 45 ° to the longitudinal direction of the pixel electrode 3. It is. An optical compensation layer 5 having a negative uniaxial refractive index anisotropy is inserted between the emission side polarizing plate 4 and the glass substrate 6. The refractive index anisotropic axis of the optical compensation layer 5 is a direction perpendicular to the substrate.

Next, the display operation of the active matrix liquid crystal display panel having this configuration will be described with reference to FIG. In addition, a color filter (color layer) 18 and the like are not shown for simplification.

When no electric field is applied and the potential difference between the pixel electrode 3 and the counter electrode 2 is 0, the liquid crystal molecules 19 having a positive dielectric anisotropy are in the initial alignment state as shown in FIG. As it is, it is oriented vertically to the substrate. Therefore,
The directions of the optically anisotropic axes are all perpendicular to the substrate, and the transmittance for vertically incident light is almost equal to 0, and black display is realized.

For incident light from an oblique direction, particularly incident light from a direction forming an azimuth angle of 45 degrees with respect to the polarization axis of the polarizing plate, the linearly polarized light after passing through the incident-side polarizing plate 10 becomes a liquid crystal. When the light passes through the layer, it becomes elliptically polarized light due to the influence of retardation. If there is no optical compensation layer, the light cannot be absorbed by the exit-side polarizing plate 4 and the transmittance becomes considerably large, resulting in a whitish display. Therefore, in the present embodiment, the optical compensation layer 5 having negative uniaxial refractive index anisotropy is disposed between the glass substrate 6 on the color filter side and the polarizing plate 4. The optical compensation layer 5 compensates for the polarization plane distorted by the retardation when passing through the liquid crystal layer, and approaches the polarization state (linearly polarized light) immediately after passing through the incident-side polarizing plate 10. As a result, the light after passing through the optical compensation layer 5 is considerably absorbed by the exit-side polarizing plate 4, and the transmittance is small and black display is performed. That is,
A stable black level can be obtained in a wide viewing angle range.

Next, a case where white display is performed by applying an electric field to the liquid crystal display panel will be described. In the present embodiment, the counter electrode 2 and the pixel electrode 3 are not provided at positions facing each other, but are provided at positions shifted alternately. Therefore, when an electric field is applied between the pixel electrode 3 and the counter electrode 2 which are alternately formed on different substrates, as shown in FIG. 3B, elliptical equipotential lines centering on each electrode are obtained. And the direction 23 of the electric field is not perpendicular to the liquid crystal layer but oblique. A torque acts on the liquid crystal molecules 19 in such a manner that the liquid crystal molecules 19 tilt in a direction to reduce the angle formed with the electric field. The inclination of the electric field is divided into two directions depending on the positional relationship between the counter electrode 2 and the pixel electrode 3.

For example, when an electric field is applied from the opposing electrode 2 to the pixel electrode 3, as shown in FIG. 3B, the electric field is applied from the opposing electrode 2 to the pixel electrode 3a and to the pixel electrode 3b. An electric field is generated. Therefore, as described with reference to FIG. 3B, oblique electric fields having different directions are generated alternately from left to right, such as downward leftward and downward rightward. That is, the direction 23 of the electric field is alternately different for each section (the section A and the section B) divided by the counter electrode 2 and the pixel electrode 3. Therefore, the direction in which the liquid crystal molecules 19 fall under the torque is alternately left and right in each section. Conventionally, by performing a special treatment such as alignment division, sections having different directions in which liquid crystal molecules fall are formed. However, according to the present invention, the positions of the counter electrode and the pixel electrode alternate on different substrates. Just provide
Sections having different directions in which liquid crystal molecules fall can be easily formed without requiring special treatment.

As described above, when the liquid crystal molecules 19 are tilted, retardation occurs in a direction at an angle of 45 degrees with the polarizing plate (a direction perpendicular to the longitudinal direction of the electrode). can get. As described above, in the present embodiment, the direction in which the liquid crystal molecules 19 fall between the section A and the section B is different. When viewed from the front, the same effect is obtained in the section A and the section B. However, when viewed from an oblique direction, the two sections A and B compensate each other. Can be seen. Therefore, a wide viewing angle characteristic can be obtained even when a white display including a halftone is viewed obliquely.

The liquid crystal molecules 19 undergo bend deformation and splay deformation due to the torque generated by the electric field. The response speed of the bend deformation and the splay deformation is considerably higher than that of the twist deformation, so that the response speed is much faster than the conventional method (IPS system) using the twist deformation by the lateral electric field.

FIG. 4 is a graph showing the relationship between the applied voltage and the transmittance in each pixel of the active matrix liquid crystal display panel prepared as described above. It can be seen that particularly good characteristics are exhibited in the range of 0 to 8 V.

FIG. 5 is a plot of the relationship between the inclination angle from the substrate normal and the transmittance when the substrate is viewed obliquely at an azimuth of 90 degrees with respect to the longitudinal direction of the scanning line 14 in FIG. It is the graph which did. FIG. 6 is a graph plotting the relationship between the inclination angle and the transmittance when the substrate is viewed obliquely in the direction of the azimuth angle of 0 °.

When viewed from the azimuth angle of 90 degrees, good display characteristics can be obtained in a wide viewing angle range. Further, the black level is stable even in the azimuth direction of 0 °, and the contrast with the white level is maintained at 5: 1 or more in a wide viewing angle range.

As described above, as a result of the compensation effect between the optical compensation layer 5 having a negative refractive index anisotropy and the regions A and B, a wide viewing angle characteristic was obtained.

The response speed is more than twice that of the IPS system which obtains a wide viewing angle characteristic by using a lateral electric field.
Good images were also obtained when displaying moving images. Specifically, the time from when the electric field is applied to when the liquid crystal molecules move to stop the application of the electric field and when the liquid crystal molecules return to the original position is 60 ms under a normal condition in the conventional IPS mode liquid crystal display panel. Although about time was required, the liquid crystal display panel of this embodiment requires only about 25 ms.

An example of the method for manufacturing the liquid crystal display panel of the present embodiment will be described in detail below.

First, the active matrix substrate X
The manufacturing method of the above will be described.

On a glass substrate (transparent insulating substrate) 6, a 150 nm Cr film is laminated as a metal layer serving as the scanning line 14 and patterned. Further, a silicon nitride film having a thickness of 400 nm, a non-doped amorphous silicon film having a thickness of 350 nm, and an n-type amorphous silicon film having a thickness of 30 nm are sequentially laminated as the gate insulating film 9.
Thereafter, an n-type amorphous silicon layer and a non-doped amorphous silicon layer are patterned to form the island-shaped amorphous silicon 1.
3 is formed. Then, a 150 nm Cr film is laminated and patterned as a metal layer to be the signal line 1 and the pixel electrode 3. Further, a protective insulating film 8 is formed, and in the peripheral terminal portion, the protective insulating film 8 and the gate insulating film 9 are formed.
Is removed to complete the TFT.

Next, a method of manufacturing the color filter substrate Y will be described.

First, a color filter (color layer) 18 is formed on a glass substrate (transparent insulating substrate) 6. Color layer 18
Is formed as follows. A photosensitive polymer containing a red pigment is formed on the substrate, and a portion other than the red filter forming region is removed by a photolithography technique to form a red filter. Next, by performing similar steps, a green filter and a blue filter are sequentially formed. Further, a Cr film is laminated to a thickness of 150 nm as a metal layer serving as the black matrix 15 and the counter electrode 2,
It is patterned. A chromium oxide layer for preventing reflection may be formed below the Cr layer. Note that the width of the pixel electrode 3 and the counter electrode 2 is 5 μm, and the interval between the electrodes is 10 μm.

The alignment films 11 and 26 are respectively applied to the active matrix substrate X and the color filter substrate Y manufactured as described above. Both alignment films 11, 26
Is vertically aligned so that the liquid crystal molecules stand perpendicular to the substrate in the initial alignment state. And both alignment films 1
After the substrates are arranged so that the substrates 1 and 26 face each other and the outer peripheral portions are fixed to each other with a sealing material (not shown), a liquid crystal material having a positive dielectric anisotropy is provided in a gap between the alignment films. The liquid crystal layer 7 is provided by being injected and sealed. The refractive index of the injected liquid crystal with respect to ordinary light is n _O = 1.476, the refractive index anisotropy is Δn = 0.077, and the cell gap is 5.5.
μm.

Although not shown, the electrodes connected to the black matrix 15 and the counter electrode 2 are connected to the terminals on the active matrix substrate side outside the display area, and the transfer for supplying the potential is performed using silver paste. It is configured.

Further, a plastic film as the optical compensation layer 5 is attached to the outside of the glass substrate 6 on the color filter side. The optical compensation layer 5 has a negative uniaxial refractive index anisotropy, and the anisotropic axis is perpendicular to the substrate. Product △ n _F · d _F of the refractive index anisotropy △ n _F and the layer thickness d _F of the optical compensation layer was 165 nm.

Two polarizing plates 4, 10 are sandwiched between the active matrix substrate X and the color filter substrate Y.
Is affixed. The directions 16 and 17 of the polarization axes are orthogonal to each other, and are set to directions that make 45 degrees with the pixel electrode 3 (see FIG. 2).

In the active matrix liquid crystal display panel manufactured as described above, good display characteristics can be obtained in a wide viewing angle range by the optical compensation layer, and the liquid crystal drive division can be smoothly performed and a high-speed response can be obtained. Was completed.

In this embodiment, since the counter electrode 2 is provided on the liquid crystal layer 7 side of the color filter (color layer) 18, the voltage applied to the liquid crystal layer 7 is substantially reduced by the effect of the dielectric constant of the color filter 18. Of the liquid crystal layer 7 due to impurities in the color filter 18 and the like.

When it is difficult to make the liquid crystal molecules completely perpendicular to the substrate surface when no electric field is applied, the liquid crystal is oriented so as to be slightly inclined with respect to the normal direction of the substrate. . Specifically, the pixel electrode 3 and the counter electrode 2
In the plane including the longitudinal direction of the glass substrate 6 and the normal line of the glass substrate 6. When the liquid crystal molecules are aligned in this way, the tilt direction does not vary, so that the alignment state and operation of the liquid crystal can be stabilized.

Although not shown, the optical compensation layer 5 has a multilayer structure, and for example, a plurality of layers having a positive uniaxial refractive index anisotropy are superimposed to form a substantially negative uniaxial refractive index anisotropy in a laminated state. May be provided. To explain this, the refractive index ellipsoid of the layer having a positive uniaxial refractive index anisotropy has an elliptical shape in a plane parallel to the substrate surface, but has an elliptical shape with its longitudinal direction shifted. When a plurality of bodies overlap, the shape becomes substantially close to a circle when viewed from above the substrate surface, and works in the same way as a negative uniaxial refractive index anisotropic refractive index ellipsoid that forms a circle in a plane parallel to the substrate surface. Can be. In the configuration of the present embodiment, the liquid crystal layer 7 having a positive uniaxial refractive index anisotropy and the optical compensation layer 5 having a negative uniaxial refractive index anisotropy overlap each other to form a refractive index ellipsoid of both. The combination has a substantially spherical shape, and the effect of the refractive index anisotropy is negated in any direction. Therefore, optical compensation is performed by the configuration of the present embodiment,
It is possible to prevent gradation inversion in which the black display portion becomes whitish.

Next, a second embodiment of the present invention will be described.
This will be described with reference to the drawings.

FIG. 7 is a plan view showing an active matrix according to the second embodiment of the present invention. The structure and manufacturing method of each layer are almost the same as those of the first embodiment shown in FIGS. As in the first embodiment, the liquid crystal layer 7 is oriented perpendicular to the substrate, and the optical compensation layer 5 having a negative uniaxial refractive index anisotropy is provided. The direction of the anisotropic axis is perpendicular to the substrate. is there. The directions 16 and 17 of the polarization axes of the polarizers are perpendicular to each other and form 45 degrees with respect to each of the signal line 1 and the scanning line 2. The used liquid crystal, its alignment state, and the optical compensation layer were the same as in the first embodiment.

In the present embodiment, sections A and B in which the longitudinal direction of the pixel electrode 21 is parallel to the signal line 1 and sections C and D in which the pixel electrode 21 is perpendicular to the signal line 1 are provided. The counter electrode 22 on the color filter substrate Y is also provided with one that is parallel to the signal line 1 and one that is perpendicular to the signal line 1.

As in the case of the first embodiment, in the state where no voltage is applied, the liquid crystal is maintained in a vertical alignment, and the optical compensation layer 5 having a negative refractive index anisotropy has a wide viewing angle range. A stable black display is obtained. Pixel electrode 21 and counter electrode 22
When a potential difference is applied between the liquid crystal molecules and the liquid crystal molecules shown in FIG.
As in the case of, it falls in the direction perpendicular to the pixel electrode 21. As a result, retardation occurs in a direction at an angle of 45 degrees with the polarizing plate, so that the transmittance increases and a white display is obtained.

In the case of this embodiment, the liquid crystal molecules in the sections A and B are perpendicular to the signal line 1 and fall in opposite directions to each other, and in the sections C and D, the liquid crystal molecules are parallel to the signal line 1 and opposite to each other. To fall. Thus, four types of different domains (regions) of sections A to D having different falling directions are formed in one pixel. These four types of domains compensate each other, and the viewing angle characteristics are further improved.

At this time, in each of the sections A to D, the distance between the pixel electrode and the counter electrode and the area of each section can be arbitrarily set. It is desirable to make the electrode spacing and area as equal as possible. Here, the width of the pixel electrode is 5 μm.
m, the electrode interval was 10 μm, and the sum of the areas of the sections A to D was all equal.

The distortion of the director of the liquid crystal molecules when a voltage is applied is almost the same as in the first embodiment, and is due to the splay deformation and the bend deformation, and a high-speed response is obtained.

The relationship between the applied voltage and the transmittance in each pixel of the active matrix liquid crystal display panel prepared as described above is almost the same as in FIG. 6, and shows good characteristics in the range of 0 to 8V.

Further, the relationship between the inclination angle from the substrate normal and the transmittance was plotted when the substrate was viewed obliquely in the direction at an azimuth of 90 degrees with respect to the longitudinal direction of the scanning line 14 in FIG. The graph is shown in FIG. When the substrate is viewed obliquely at the azimuth angle of 0 °, the viewing angle characteristics are almost the same as when the substrate is viewed at the azimuth angle of 90 °. Compared with the example based on the first embodiment, the present embodiment can obtain very good display characteristics in a wider viewing angle range. This is the compensation effect of the two types of sections A and B in the first embodiment, whereas the four types of sections A to D compensated in the second embodiment. The effect is.

Also, as in the case of the first embodiment, the response speed is such that a wide viewing angle characteristic is obtained by using a lateral electric field.
As compared with the S method, the image was twice or more, and a good image was obtained even when a moving image was displayed.

As described above, in the two embodiments, the optical compensation layer is sandwiched between the output side polarizing plate 4 and the glass substrate 6, but as shown in FIG. The optical compensation layer 25 perpendicular to the substrate 6 can be configured to be sandwiched between the incident side polarizing plate 10 and the glass substrate 6, and almost the same effects as those of the two embodiments can be obtained. .

As shown in FIG. 10, the optical compensation layers 26 and 27 whose anisotropic axes are perpendicular to the glass substrate 6 are provided between the exit-side polarizing plate 4 and the glass substrate 6 and between the exit-side polarizing plate 10 and the entrance-side polarizing plate 10. It is also possible to adopt a configuration provided on both sides of the glass substrate 6.

[0061]

As described above, the present invention has the following effects.

1) An active matrix liquid crystal display panel according to a first aspect of the present invention uses a liquid crystal having a positive dielectric anisotropy at a high speed and a wide viewing angle without significantly complicating the manufacturing process. A display panel can be realized, and furthermore, a grayscale inversion phenomenon in which a black display portion looks whitish can be suppressed.

2) According to the third aspect of the invention, the light use efficiency at the time of white display can be maximized.

3) According to the fourth aspect of the invention, the manufacturing process can be simplified.

4) According to the fifth aspect of the invention, the voltage drop due to the color filter can be prevented, and the electric field applied to the liquid crystal layer can be effectively formed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a plan view of a main part of the first embodiment.

FIG. 3 is a cross-sectional view illustrating an operation of the first embodiment.

FIG. 4 is a diagram illustrating a relationship between an applied voltage and transmittance according to the first embodiment.

FIG. 5 is a diagram illustrating a relationship between an inclination angle and a transmittance at an azimuth angle of 90 degrees in the first embodiment.

FIG. 6 is a diagram illustrating the relationship between the inclination angle and the transmittance when the azimuth angle is 0 degrees in the first embodiment.

FIG. 7 is a plan view of a main part of the second embodiment.

FIG. 8 is a diagram illustrating a relationship between a tilt angle and a transmittance at an azimuth angle of 90 degrees in the second embodiment.

FIG. 9 is a cross-sectional view of a third embodiment of the present invention.

FIG. 10 is a sectional view of a fourth embodiment of the present invention.

FIG. 11 is a perspective view of a conventional IPS type liquid crystal display panel.

FIG. 12 is a cross-sectional view of a conventional vertically aligned liquid crystal display panel.

FIG. 13 is a diagram showing the relationship between voltage and transmittance in a conventional TN mode liquid crystal display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal line 2, 22 Counter electrode 3, 3a, 3b, 21 Pixel electrode 4, 10 Polarizer 5, 25, 26, 27 Optical compensation layer 6 Glass substrate (transparent insulating substrate) 7 Liquid crystal layer 8 Protective insulating film 9 Gate Insulating film 11, 20 Alignment film 12 Storage capacitor 13 Island-shaped amorphous silicon 14 Scan line 15 Black matrix 16, 17 Polarization axis direction 18 Color filter (color layer) 19 Liquid crystal molecule 23 Direction of electric field

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1335 510 G02F 1/136 500

Claims (5)

(57) [Claims] 1. A plurality of scanning lines and a plurality of signal lines, which are arranged on one of a pair of transparent insulating substrates so as to cross each other to form a grid, and the scanning lines and the signals A plurality of active elements provided in the vicinity of each intersection of the lines, and a plurality of parallel linear pixel electrodes connected to the active elements are provided, and the other transparent insulating substrate includes A plurality of parallel linear opposing electrodes are provided corresponding to the pixel electrodes and a voltage is applied between the pixel electrodes, and a liquid crystal layer is provided between the two transparent insulating substrates. In an active matrix liquid crystal display panel in which a polarizing plate is disposed outside each of the transparent insulating substrates, the pixel electrode and the counter electrode alternate with each other avoiding a position facing each other. Are arranged as follows, The liquid crystal layer has a positive dielectric anisotropy, and the director of liquid crystal molecules is substantially perpendicular to the transparent insulating substrate when the voltage between the pixel electrode and the counter electrode is 0. An optical compensation layer having a negative uniaxial refractive index anisotropy is disposed between at least one of the transparent insulating substrate and the polarizing plate, and the optical compensation layer is anisotropically oriented. An active matrix liquid crystal display panel, wherein the direction of the axis is substantially perpendicular to the transparent insulating substrate. 2. The optical compensation layer according to claim 1, wherein the optical compensation layer has a multilayer structure, and a plurality of layers having a uniaxial refractive index anisotropy are superposed to have a substantially negative uniaxial refractive index anisotropy.
4. The active matrix liquid crystal display panel according to 1. 3. The active matrix liquid crystal display panel according to claim 1, wherein the polarization axes of the two polarizing plates are orthogonal to each other, and an angle between each of the pixel electrodes and the opposite electrode is 45 degrees. . 4. The color filter according to claim 1, wherein the transparent insulating substrate on which the counter electrode is formed is provided with a color filter, and the counter electrode and the black matrix are formed in the same layer. 2. The active matrix liquid crystal display panel according to claim 1. 5. The active matrix liquid crystal display panel according to claim 4, wherein said counter electrode and said black matrix are located closer to said liquid crystal layer than said color filters.