JPH04285917A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obviate the orientation disorder of a liquid crystal molecule generated in one picture element, and to obtain the display of a high picture quality, in the liquid crystal display device having plural picture elements. CONSTITUTION:In a shape of a picture element electrode 2 formed on the lower substrate, chamfering R consisting of a straight line or a circular arc is performed to at least one corner part. As a result, an electric field concentration generated in the corner part in the case a voltage is applied to the picture element electrode 2 can be relieved, and also, the picture element electrode 2 is separated from a step difference of a source wiring 12 and a gate wiring 13, and an orientation failure part by a rubbing method comes not to be positioned on the picture element electrode 2, therefore, generation of an orientation disorder of a liquid crystal molecule by a horizontal electric field and an orientation failure can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition, high-quality liquid crystal display device that utilizes electro-optic effects.

0002

[Background Art] In recent years, liquid crystal display devices that utilize the electrical and optical anisotropy of liquid crystals have been widely used as flat displays in portable computers, pocket TVs, etc., and demand will continue to increase in the future. is expected.

FIG. 9 shows a cross-sectional view of a portion of a typical active matrix twisted nematic type liquid crystal display device.

[0004] This liquid crystal display device is mainly formed from two glass substrates and a liquid crystal layer between them. On the lower substrate 7b, a thin film transistor 3 is provided for controlling the voltage applied to the pixel electrode 2 for each of a plurality of pixels provided in a matrix.
The upper substrate 7a includes a color filter 9 consisting of red, green, and blue, and a thin film transistor 3 that separates each color.
and a black mask 6 for shielding the wiring portion from light, and
A counter electrode 5 is provided. A liquid crystal layer 1 having a twist angle of 90 degrees in the molecular direction is provided between them.

[0005] An alignment film 4 made of polyimide is provided on the inner surfaces of the upper and lower substrates in order to align liquid crystal molecules, and an alignment treatment is performed by a rubbing method. Further, polarizing plates 10 are arranged on the outside of the upper and lower substrates, respectively.
Their polarization axes are orthogonal, and the display is in a normally white mode, with a bright display when no voltage is applied and a dark display when a voltage is applied.

FIG. 10 is an electrode configuration diagram showing the pixel electrode 2 and the thin film transistor 3 of the lower substrate 7b of the liquid crystal display device, the wiring for applying voltage to the thin film transistor 3, and the like.

As shown in the figure, the source wiring 12 for supplying a signal voltage and the gate wiring 13 for supplying a scanning voltage are orthogonal to each other, and the pixel electrode 2 connected to the drain terminal 14 of the thin film transistor 3 crosses at right angles. The shape is almost rectangular. Further, the orientation treatment direction is from diagonally upper right to diagonally lower left, as shown by the arrow in the figure.

The operation of the liquid crystal display device configured as described above will be explained below with reference to FIG. 11. FIG. 11 shows a lower substrate 7b of a liquid crystal display device having a plurality of pixels.
3 is a signal waveform diagram showing the voltage state of a wiring connected to one thin film transistor 3 formed above. FIG.

Among the pixel parts arranged in a matrix,
A source signal 16, which is a rectangular wave AC voltage of several volts, is applied to the source wiring 12 connected to the thin film transistor 3 installed in a specific pixel, and a pulse-like voltage that is sufficiently shorter than the AC period of the source is applied. The gate signal 17 is
When is applied to the gate wiring, charge flows into the pixel electrode 2 portion during that time, and a pixel electrode voltage 18 is generated.

[0010] Therefore, a potential difference is generated between the counter electrode 5 across the liquid crystal layer 1 and the selected pixel electrode 2 portion. As a result, due to the dielectric anisotropy of the liquid crystal molecules, a force is generated in the liquid crystal molecules located between them that causes the long axis of the molecules to align with the direction of the electric field, and the twisted arrangement of the liquid crystal molecules is resolved, causing light to be emitted. The rotational property is lost, and the light is blocked by the polarizing plate whose polarization axes are orthogonally arranged, resulting in a dark display in the pixel area.

[0011]

However, the above conventional configuration has the following problems.

FIG. 12 is an enlarged view of a portion of the conventional liquid crystal display device in a display state, and corresponds to FIG. 10 in terms of vertical and horizontal relationships.

As shown in FIG. 12, when no voltage is applied or when displaying halftones, there is a part in the upper right corner of each pixel 20 where the brightness is different from other parts, and the brightness is even greater at the boundary part. A change in brightness can be seen.

[0014] Such uneven brightness leads to deterioration of contrast and display quality, and becomes a major defect in the display device. This defect is more likely to occur in devices with high pixel density, and is a serious problem in high-definition, high-quality liquid crystal display devices. This luminance unevenness within a pixel is caused by disordered alignment of liquid crystal molecules, and is caused by a combination of several factors listed below.

The first factor is that the alignment regulating force is non-uniform. In the above structure, the inner surfaces of the upper and lower substrates are subjected to alignment treatment to orient the liquid crystal molecules.

FIG. 13(a) shows a schematic diagram of this orientation method.
FIG. 13(b) shows an enlarged cross-sectional view of the alignment treatment state on the substrate unevenness. As a method for this orientation, a rubbing method in which the polyimide film applied to the surface of the substrate 7 is rubbed in one direction with a raised non-twisted cloth 21 is generally used, and is also excellent in mass production.

However, as shown in FIG. 13(b), due to irregularities on the substrate such as the source wiring 12 and gate wiring, a defective alignment portion A is generated where the tips of the bristles of the rubbing cloth 21 do not touch. The alignment regulating force of liquid crystal molecules in this part is weak and becomes an unstable part.

On the other hand, in a 90 degree twisted nematic liquid crystal display device, the alignment direction is set obliquely to the end surface of the substrate in order to obtain bilaterally symmetrical viewing angle characteristics. Although the orientation direction with respect to the lower substrate 7b is shown in FIG. 10 shown above, each pixel 20 is naturally rubbed with the rubbing cloth 21 from an oblique direction to undergo an orientation treatment.

Here, the gate wiring 13 and the source wiring 12
The pixel electrode 2 has a large film thickness and is made of ITO.
There is a difference in level of about 0.5 to 1.0 μm from the part. Therefore, for the reason mentioned above, the pixel electrode 2 near the wiring part
The alignment regulating force is weak around the corner E1 shown in FIG. 2, in particular.

The second factor is that the electric field strength applied to the liquid crystal layer 1 is non-uniform. When a voltage is applied to the pixel electrode 2, an electric field is concentrated at the edges of the pixel electrode 2, particularly at the corners, and a larger electric field acts on the liquid crystal molecules in that area than in other areas.

The third factor is due to non-uniformity in the direction of electric lines of force and resulting non-uniformity in the rising direction of liquid crystal molecules when voltage is applied.

According to the liquid crystal alignment method using the above-mentioned rubbing method, the liquid crystal molecules aligned thereby stand up in a specific direction from the substrate surface. This rising angle is called a tilt angle, and in particular, the tilt angle when no voltage is applied is called a pretilt angle. In the case of a 90 degree twisted nematic, this pretilt angle is about 2 degrees.

FIG. 14(a) is a diagram showing the relationship between the orientation treatment direction by rubbing on the substrate surface and the rising direction of the liquid crystal molecules 24, and FIG. 3 is a diagram illustrating the relationship between lines of electric force generated between the two and the direction in which liquid crystal molecules 24 rise due to voltage application. FIG.

The direction of the electric lines of force differs between the ends and the center of the pixel electrode 2, and the liquid crystal molecules 24
It can be seen that the liquid crystal molecules 24 rise in the opposite direction to the other parts in relation to the pretilt angle.

Furthermore, the fourth factor is that the alignment of the liquid crystal molecules 24 is disturbed by the electric field generated between the wiring sections. At time A shown in FIG. 11, the source signal 16 is at a positive potential and the gate signal 17 is at a negative potential, resulting in a large potential difference. Therefore, a planar electric field (hereinafter, this electric field will be referred to as a transverse electric field) exists at the intersection of the source wiring 12 and gate wiring 13 shown in FIG. 10 and its surroundings.
occurs.

Since the corner of the pixel electrode 2 is located at the intersection of the source line 12 and the gate line 13, an electric field other than the electric field between the electrodes facing each other via the liquid crystal layer 1 is generated in this area. It can be seen that it works.

The present invention solves the above-mentioned conventional problems, and aims to provide a liquid crystal display device that is free from alignment defects of liquid crystal molecules, has no uneven brightness, and can obtain high contrast and good image quality. purpose.

[0028]

[Means for Solving the Problems] In order to achieve this object, the liquid crystal display device of the present invention has the shape of the electrode of each pixel for applying a voltage to the liquid crystal layer to a circular arc, a substantially circular arc, or a straight line at the corner. It has a chamfered shape.

Alternatively, the planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is a polygon with each corner formed at an obtuse angle.

Alternatively, the cross-sectional shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is a shape in which corners are chamfered with circular arcs, substantially circular arcs, or straight lines.

Alternatively, the shape of the pixel is such that at least one side of the pixel is approximately perpendicular to the direction of alignment treatment of the substrate having the pixel electrode.

Alternatively, at least one corner of the intersection of the source wiring and gate wiring to the switching element provided in each pixel is provided with a surface that intersects with the two wirings at an obtuse angle.

[0033]

[Operations] The above-mentioned configurations produce the following effects, and it is possible to obtain a liquid crystal display device that is free from alignment defects of liquid crystal molecules, has no uneven brightness, and can obtain good image quality.

First, the planar shape of the electrode of each pixel for applying voltage to the liquid crystal layer is chamfered with circular arcs, approximately circular arcs, or straight lines at the corners, thereby reducing the concentration of electric field generated at the corners. can be relaxed, and the voltage applied to the liquid crystal molecules can be made uniform. Further, the distance of the pixel electrode can be increased from the wiring step portion where the alignment regulating force is unstable, and furthermore, the pixel electrode can be distanced from the intersection of the source wiring and the gate wiring where a transverse electric field is generated. Because of this, it becomes possible to prevent alignment disorder of liquid crystal molecules on the pixel electrode.

[0035] The same effect as above can also be obtained by making the planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer polygonal with obtuse angles. .

On the other hand, the cross-sectional shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is chamfered with a circular arc, a substantially circular arc, or a straight line at the corner, so that the end of the pixel electrode at the corner is It is possible to alleviate the electric field concentration that occurs in some areas, to make the voltage applied to the liquid crystal molecules uniform, and to prevent the arrangement of liquid crystal molecules on the pixel electrode from being disordered.

Furthermore, by forming a pixel shape in which at least one side of the pixel is substantially perpendicular to the direction of alignment processing on the substrate having the pixel electrode, the direction of the electric force lines at the corners of the pixel electrode where the electric field is concentrated and the direction of the liquid crystal This prevents the rising direction of molecules from the substrate surface from being reversed, and it becomes possible to prevent disordered alignment of liquid crystal molecules on the pixel electrode.

Furthermore, by providing a surface that intersects at an obtuse angle with respect to both wiring lines at at least one corner of the intersection of the source wiring and gate wiring to the switching element provided in each pixel, the source wiring and the gate wiring can be easily connected. Since the transverse electric field generated at the intersection can be relaxed, it is possible to prevent the alignment of liquid crystal molecules on the pixel electrode from being disordered.

[0039]

[Example] (Example 1) Below, regarding the first example,
This will be explained with reference to the drawings.

FIG. 1 is a plan view showing the structure of electrodes such as pixel electrodes, thin film transistors, and wiring on the lower substrate in a first embodiment of the liquid crystal display device of the present invention. This is an active matrix normally white mode twisted nematic type liquid crystal display device.

In FIG. 1, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal.

Furthermore, the panel configuration of this embodiment is almost the same as the cross-sectional view of the conventional example shown in FIG. 9, and the signal waveform indicating the voltage state for one thin film transistor 3 is the same as the signal waveform of the conventional example shown in FIG. is the same as

In this embodiment, as shown in FIG.
For each pixel electrode 2 arranged in a matrix on b,
A chamfer C consisting of a straight line is applied to the convex corner. The pixel pitch is 80 μm in the horizontal direction and 100 μm in the vertical direction, and the size of the chamfer is about 5 μm.

[0044] By forming the pixel electrode in such a shape, electric field concentration occurring at the corners can be alleviated, and the voltage applied to the liquid crystal molecules can be made uniform. Furthermore, the pixel electrode 2 can be spaced apart from the wiring step portion where the alignment regulating force is unstable, and furthermore, it can be spaced away from the intersection between the source wiring 12 and the gate wiring 13 where a transverse electric field is generated. For this reason, it is possible to prevent the arrangement of liquid crystal molecules on the pixel electrode 2 from being disordered.

In addition, the shape of the opening of the black mask provided on the upper substrate 7a is chamfered in the same manner as the shape of the pixel electrode 2.

With the above-described configuration, the liquid crystal display device of this example was able to eliminate the brightness unevenness shown in FIG. 14 and obtain high contrast and good image quality.

(Embodiment 2) A second embodiment will be described below with reference to the drawings.

FIG. 2 is an electrode configuration diagram showing the pixel electrodes, thin film transistors, wiring, etc. on the lower substrate of the second embodiment of the device of the present invention. This is a twisted nematic type liquid crystal display device in Maliblack mode.

In FIG. 2, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal.

Furthermore, the panel configuration of this embodiment is almost the same as the cross-sectional view of the conventional example shown in FIG. 9, and the signal waveform indicating the voltage state for one thin film transistor 3 is the same as the signal waveform of the conventional example shown in FIG. is the same as

In this embodiment, as shown in FIG.
The shape of each pixel electrode 2 arranged in a matrix with 1/2 pixel shifted every line on b is octagonal. The pixel pitch is 85 μm in the horizontal direction and 80 μm in the vertical direction.

By forming the pixel electrode in such a shape, all the corners become obtuse angles, which makes it possible to alleviate electric field concentration occurring at the corners, and to equalize the voltage applied to the liquid crystal molecules. Furthermore, the pixel electrode 2 can also be seen from the intersection where the source wiring 12 and the gate wiring 13 intersect at an acute angle, where a horizontal electric field is generated.
The configuration is such that they are separated from each other. For this reason, it is possible to prevent the arrangement of liquid crystal molecules on the pixel electrode 2 from being disordered.

Due to the above-described effects, the liquid crystal display device of this example was able to obtain good image quality without uneven brightness.

(Embodiment 3) A third embodiment will be described below with reference to the drawings.

FIG. 3(a) is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. on the lower substrate of a liquid crystal display device showing a third embodiment of the present invention, and FIG. 3(b) is an electrode configuration diagram showing the pixel electrode, thin film transistor, wiring, etc.
It is a figure which shows the cross-sectional shape of the AA part in (a). This is an active matrix normally black mode twisted nematic type liquid crystal display device in which each pixel has one thin film transistor.

In FIG. 3, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal, and 7b is a lower substrate.

In this embodiment, as shown in FIG. 3(a), for each pixel electrode 2 arranged in a matrix on the lower substrate 7b, a straight line is formed at the convex corner as in the first embodiment. As shown in FIG. 3(b), even in the cross-sectional shape, the corner portion facing the liquid crystal layer 1 is chamfered with a straight line C1. Chamfer C1 for this cross-sectional shape
The size is approximately 0.1 μm.

By adopting such a shape of the pixel electrode, electric field concentration can be further relaxed than in the first embodiment, and the voltage applied to the liquid crystal molecules can be made uniform. For this reason, it becomes possible to more effectively prevent the arrangement of liquid crystal molecules on the pixel electrode 2 from being disordered.

Due to the above-mentioned effects, the liquid crystal display device of this example was able to obtain good image quality without uneven brightness.

(Embodiment 4) A fourth embodiment will be described below with reference to the drawings.

FIG. 4 is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. on the lower substrate of a device according to a fourth embodiment of the present invention. This is a twisted nematic type liquid crystal display device in Mariwhite mode.

In FIG. 4, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal.

In this embodiment, as shown in FIG.
For each pixel electrode 2 arranged in a matrix on b,
Chamfering R consisting of an arc is applied only to the corner of the protruding portion in the orientation direction indicated by the arrow in the figure. The pixel pitch is 80 μm in the horizontal direction and 100 μm in the vertical direction, and the radius of the chamfer is about 10 μm.

In this example, the corner portion is where electric field concentration occurs, and is likely to become a defective portion due to the orientation treatment by the rubbing method as shown in FIG. 13(b) of the conventional example.
The liquid crystal molecules on the pixel electrode 2 shown in 4(a) and 4(b) are chamfered only at the part where the rising direction of the liquid crystal molecules 24 is likely to be reversed, which is caused by the combination of poor alignment and electric field concentration. This makes it possible to prevent the arrangement of 24 items from being disordered.

In addition, the shape of the opening of the black mask provided on the upper substrate 7a is such that only one corner is chamfered, similar to the shape of the pixel electrode 2. For this reason, this embodiment can ensure the same pixel electrode and pixel aperture area as the conventional example, and can provide a bright display with a high aperture ratio, which is particularly effective for high-density liquid crystal display devices. Ru.

Due to the above-mentioned effects, the liquid crystal display device of this example was able to obtain good image quality without uneven brightness.

(Embodiment 5) A fifth embodiment of the apparatus will be described below with reference to the drawings.

FIG. 5 is an electrode configuration diagram showing the pixel electrodes, thin film transistors, wiring, etc. on the lower substrate of the fifth embodiment of the device of the present invention. This is a normally white mode twisted nematic type liquid crystal display device.

In FIG. 5, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal.

In this embodiment, as shown in FIG. 5, the square pixel electrode 2 has a structure in which its vertices are located at the top, bottom, left and right, and one side of the square pixel electrode 2 is located in a direction perpendicular to the alignment direction by the rubbing method. ing.

By adopting such a configuration, the direction of the electric field lines between the pixel electrode and the counter electrode 5 due to electric field concentration generated at the two corners of the pixel electrode, and the liquid crystal molecules shown in FIGS. 14(a) and 14(b) This means that the direction in which the liquid crystal molecules 24 rise is shifted by about 45 degrees, making it possible to prevent disordered alignment of the liquid crystal molecules 24 on the pixel electrode 2, which is caused by a combination of defective factors causing the liquid crystal molecules 24 to rise in the opposite direction and defective factors due to electric field concentration. Become.

Due to the above-mentioned effects, the liquid crystal display device of this example was able to obtain good image quality without uneven brightness.

(Embodiment 6) A sixth embodiment will be described below with reference to the drawings.

FIG. 6 is a sectional view showing a schematic configuration of a device according to a sixth embodiment of the present invention, which has a mixed layer of nematic liquid crystal and high polymer between upper and lower electrodes, and displays by switching between scattering and transmission of light. This is a liquid crystal display device that performs

Further, the lower substrate 7 of the liquid crystal display device of this embodiment
The electrode structure showing the pixel electrode 2, thin film transistor 3, wiring, etc. in b is the same as in FIG. 1 shown in Example 1.

In a liquid crystal display device such as this embodiment in which nematic liquid crystal 26 is dispersed in polymer 25 and display is switched by diffusion and transmission of light, the electric field is generally concentrated at the corner of pixel electrode 2. This caused uneven brightness within one pixel.

In contrast, in this embodiment, by chamfering the corners of the pixel electrode 2, electric field concentration is alleviated, and uneven brightness within one pixel can be eliminated.

Furthermore, by chamfering the cross-sectional shape of the pixel electrode 2 as shown in FIG. 3, even greater effects can be obtained by eliminating uneven brightness.

As described above, in the liquid crystal display device of this example, good image quality without uneven brightness could be obtained.

(Embodiment 7) A seventh embodiment will be described below with reference to the drawings.

FIG. 7(a) is a sectional view showing a schematic configuration of a device according to a seventh embodiment of the present invention, in which alignment films 4 for vertical alignment are formed on the inner surfaces of the upper and lower substrates, and a liquid crystal layer 1 is formed on the inner surfaces of the upper and lower substrates. is filled with liquid crystal with negative dielectric anisotropy.

FIG. 7(b) is a conceptual diagram showing the arrangement of liquid crystal molecules in the liquid crystal display device of this embodiment. When no voltage is applied, the liquid crystal molecules 24 are arranged perpendicularly to the substrate, that is, homeotropically arranged. However, when voltage is applied, liquid crystal molecules 2
4 are arranged parallel to the substrate.

Further, the lower substrate 7 of the liquid crystal display device of this embodiment
The electrode structure showing the pixel electrode 2, thin film transistor 3, wiring, etc. in b is the same as in FIG. 1 shown in Example 1.

Even in the homeotropically aligned liquid crystal display device as in this embodiment, electric field concentration occurs at the corners of the pixel electrode 2, and furthermore, the direction of the lines of electric force between it and the counter electrode 5 differs at the four corners. The directions in which the liquid crystal molecules 24 fall are also partially different, resulting in uneven brightness and uneven viewing angle characteristics.

In contrast, in this embodiment, by chamfering the corners of the pixel electrode 2, electric field concentration is alleviated, and unevenness in brightness and viewing angle characteristics can be eliminated.

Furthermore, by chamfering the cross-sectional shape of the pixel electrode 2 as shown in FIG. 3, even greater effects can be obtained by eliminating uneven brightness.

As described above, the liquid crystal display device of this example was able to provide good image quality without uneven brightness or uneven viewing angle characteristics.

(Embodiment 8) An eighth embodiment will be described below with reference to the drawings.

FIG. 8 is an electrode configuration diagram showing the pixel electrodes, thin film transistors, wiring, etc. on the lower substrate of the eighth embodiment of the device of the present invention. This is a twisted nematic type liquid crystal display device in Maliblack mode.

In FIG. 8, 2 is a pixel electrode, 3 is a thin film transistor, 12 is a source wiring, 13 is a gate wiring, 1
4 is a drain terminal.

Furthermore, the panel configuration of this embodiment is almost the same as the cross-sectional view of the conventional example shown in FIG. 9, and the signal waveform indicating the voltage state for one thin film transistor 3 is the same as the signal waveform of the conventional example shown in FIG. is the same as

In this embodiment, as shown in FIG. 8, a protrusion formed by the source line 12 in the 45-degree direction is provided at the intersection of the source line 12 and the gate line 13, corresponding to the upper right corner of the pixel electrode. It intersects with the gate wiring 13 at 45 degrees.

[0093] By adopting such a wiring configuration, it is possible to alleviate the generation of a transverse electric field that occurs when the polarities of the voltages applied to the source wiring 12 and the gate wiring 13 are different, which disturbs the arrangement of liquid crystal molecules. The cause can be eliminated.

This embodiment is a normally black mode, and in order to prevent alignment disorder of liquid crystal molecules over the entire surface, the opening of the black mask provided on the upper substrate 7a is larger than the pixel electrode 2, and the shape is chamfered. Since the aperture ratio is not required, the aperture ratio can be increased and a bright display can be easily obtained.

Due to the above-mentioned effects, the liquid crystal display device of this example was able to provide a good image quality with high contrast and no uneven brightness.

In this embodiment, the protrusion of the source wiring 12 is provided only at the upper right part of the pixel electrode 2, where the alignment of the liquid crystal is most likely to occur in terms of the alignment direction by the rubbing method, but it may be provided at all interconnection intersections. It is also effective to configure the gate wiring 13 in a similar shape.

In the embodiment described above, three
Although only the case with a terminal switching element is shown,
Of course, a two-terminal switching element may be used, and a simple matrix liquid crystal display device without a switching element is also effective.

Further, in the embodiment described above, an example was shown in which the pixel electrode 2 was chamfered, but it is also possible to pattern the counter electrode 5 corresponding to each pixel and chamfer the corners. A similar effect can be obtained by the same method, and an even greater effect can be obtained by performing this together with the chamfering of the pixel electrode 2.

As described above, the present invention is an effective method for improving the contrast and image quality of a wide variety of liquid crystal display devices, and furthermore, the present invention is an effective method for improving the contrast and image quality of a wide variety of liquid crystal display devices. This is a particularly effective method for increasing the pixel density and image quality of display devices.

[0100]

As described above, in the liquid crystal display device of the present invention, the planar shape of the electrode of each pixel for applying voltage to the liquid crystal layer is chamfered at the corners with circular arcs, approximately circular arcs, or straight lines. Shape.

Alternatively, the planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is a polygon with each corner formed at an obtuse angle.

Alternatively, the cross-sectional shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is a shape in which corners are chamfered with circular arcs, approximately circular arcs, or straight lines.

Alternatively, the shape of the pixel is such that at least one side of the pixel is approximately perpendicular to the direction of alignment treatment of the substrate having the pixel electrode.

Alternatively, at least one corner of the intersection of the source wiring and gate wiring to the switching element provided in each pixel is provided with a surface that intersects with the two wirings at an obtuse angle.

With these configurations, it is possible to obtain a liquid crystal display device that does not cause orientation defects of liquid crystal molecules, has no uneven brightness, and can obtain good image quality.

[Brief explanation of the drawing]

FIG. 1 is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of a lower substrate showing a first embodiment of a liquid crystal display device of the present invention.

FIG. 2 is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of the lower substrate in the second embodiment of the device of the present invention.

FIG. 3(a) is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of the lower substrate in a device according to a third embodiment of the present invention; FIG. 3(b) is a cross-sectional view taken along line A-A in FIG. 3(a);

[Figure 4
] Electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of the lower substrate in the fourth embodiment of the present invention.

FIG. 5 is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of a lower substrate in a fifth embodiment device of the present invention;

FIG. 6 is a sectional view showing a schematic configuration of a liquid crystal display device in a sixth embodiment of the present invention.

FIG. 7(a) is a sectional view showing a schematic configuration of a device according to a seventh embodiment of the present invention; FIG. 7(b) is a conceptual diagram showing an arrangement of liquid crystal molecules in a liquid crystal display device of this embodiment;

FIG. 8 is an electrode configuration diagram showing pixel electrodes, thin film transistors, wiring, etc. of the lower substrate in the eighth embodiment of the device of the present invention;

[Figure 9] Partial cross-sectional view of a conventional active matrix twisted nematic type liquid crystal display device

FIG. 10 is an electrode configuration diagram showing a pixel electrode, a thin film transistor, wiring for applying voltage to the thin film transistor, etc. on a lower substrate of a conventional liquid crystal display device.

FIG. 11: 1 formed on the lower substrate 7b of the liquid crystal display device.
A signal waveform diagram showing the voltage state of the wiring connected to two thin film transistors 3

[Fig. 12] Enlarged diagram showing the display state of a conventional liquid crystal display device.

FIG. 13 (a) is a schematic diagram of the orientation method (b) is an enlarged cross-sectional view of the alignment treatment state on the substrate unevenness.

[Figure 1
4] (a) is a diagram showing the relationship between the direction of alignment treatment on the substrate surface by the rubbing method and the rising direction of liquid crystal molecules. Relationship diagram of rising direction

[Explanation of symbols]

1 Liquid crystal layer 2 Pixel electrode 3 Thin film transistor 4 Alignment film 5 Counter electrode 7a Upper board 7b Lower board 12 Source wiring 13 Gate wiring 24 Liquid crystal molecules

Claims (11)

[Claims] 1. The planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is characterized in that at least one corner is chamfered with a circular arc, a substantially circular arc, or a straight line. A liquid crystal display device with multiple pixels. 2. A liquid crystal display device having a plurality of pixels, characterized in that the planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is a polygon with each corner formed at an obtuse angle. . 3. The cross-sectional shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is characterized in that at least one corner is chamfered with a circular arc, a substantially circular arc, or a straight line. A liquid crystal display device with multiple pixels. Claim 4: The liquid crystal is of a twisted nematic type in which the liquid crystal molecules are arranged in a twisted manner when no voltage is applied.
3. The liquid crystal display device according to 2 or 3. 5. The liquid crystal display device according to claim 4, wherein the planar shape of the electrode of each pixel for applying a voltage to the liquid crystal layer is chamfered only at the corners of the part entering the alignment process. . 6. As the planar shape of the electrode of each pixel for applying voltage to the liquid crystal layer, only the corners located in the opposite direction from the rising side of the liquid crystal molecules near the substrate having the pixel electrode from the substrate are chamfered. 5. The liquid crystal display device according to claim 4, wherein: 7. A twisted nematic liquid crystal display device, characterized in that at least one side of the pixel is substantially perpendicular to the direction in which a substrate having a pixel electrode is aligned. 8. Claims 1 and 2 characterized in that a liquid crystal layer comprising a liquid crystal and a polymer is provided between the upper and lower electrodes.
or the liquid crystal display device according to 3. 9. The liquid crystal display device according to claim 1, wherein the liquid crystal molecules are homeotropically aligned substantially perpendicular to at least one of the substrates when no voltage is applied. 10. The liquid crystal display device according to claim 1, wherein each pixel includes at least one switching element. 11. At least one corner of an intersection between a source wiring and a gate wiring for at least one switching element provided in each pixel is provided with a surface that intersects at an obtuse angle with respect to both wirings. A liquid crystal display device with multiple pixels.