JPH11125835A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device with an excellent visual angular characteristic and excellent contrast and without gradation inversion and a color shift by making an electric field distribution formed by a liquid crystal drive electrode and a common electrode opposite to the liquid crystal drive electrode so as to become the distribution making a center of a pixel a line symmetry axis. SOLUTION: This device is constituted so that the liquid crystal drive electrode 4 and the common electrode 3 opposite to the liquid crystal drive electrode 4 are bent to an alignment direction of a liquid crystal molecule, and respective electrodes are projected in the projection part direction of a bend in a bend part of a pixel central part, and respective electrodes are bent in the recessed part direction of the bend. Then, the electric field distribution formed with the liquid crystal drive electrode 4 and the common electrode 3 opposite to the liquid crystal electrode 4 is made so as to become the distribution making the center of the pixel the line symmetry axis. In such a manner, when a horizontal electric field is applied in a pixel electrode, the liquid crystal molecule is rotation moved in two ways of left rotation and right rotation in the pixel electrode inside. Thus, the color shift and the gradation inversion hardly occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-screen active-matrix liquid crystal display device having a wide viewing angle and high image quality.

[0002]

2. Description of the Related Art A method of applying an electric field to a liquid crystal composition layer using a pair of comb-like electrodes formed on one substrate of a conventional active matrix type liquid crystal display device is disclosed in, for example, JP-A-7-36058 or It is proposed in JP-A-7-159786, JP-A-6-160878 and JP-A-7-191336. Hereinafter, a display method in which the main electric field direction applied to the liquid crystal composition layer is substantially parallel to the substrate interface is referred to as a horizontal electric field method. 1 and 3 show examples of the conventional in-plane switching method. The liquid crystal drive electrode and the common electrode, which are comb-shaped pixel electrodes, are linearly arranged in parallel. The shape of the liquid crystal driving electrode and the common electrode is formed such that the electric field distribution in the pixel electrode at the center of the pixel and at the periphery of the pixel is rotationally symmetric with respect to the center of the pixel. As shown in FIG. 2 and FIG. 4, the rotational movement direction of the liquid crystal molecules is only one direction inside one pixel.

[0003]

In a horizontal electric field type liquid crystal panel in which the pixel electrodes are linear and the rotational movement direction of liquid crystal molecules is only one direction, a color shift in which the left and right colors look different when viewed from the lateral direction. There is a problem. Further, when the pretilt angle of the liquid crystal increases by 3 degrees or more, the viewing angle characteristic deteriorates, and a grayscale inversion phenomenon in a halftone region occurs, resulting in an extremely unnatural image display.

A liquid crystal panel of a horizontal electric field type in which a pixel electrode is bent has been proposed, but disclination defects occur frequently due to dripping of the bent portion and the electric field around the pixel, so that the black level is remarkably deteriorated. As a result, the screen becomes uneven.

On the side of the lateral electric field type active matrix substrate, the area of the intersection between the common electrode and the liquid crystal drive electrode is large, and if there is a defect such as a pinhole in the insulating film, it is likely to cause a short circuit and a pixel defect. In order to reduce the process cost, a method of simultaneously forming the scanning signal wiring and the common electrode has been used. In this process,
When there is a pattern failure due to a large number of regions where the scanning signal wiring and the common electrode are close to each other, a short circuit between the scanning signal wiring and the common electrode cannot be avoided, and the yield is very poor.

In a horizontal electric field type liquid crystal display device, the liquid crystal driving voltage tends to be higher than that in a conventional vertical electric field type TN liquid crystal display device. There was a problem.

In a horizontal electric field type liquid crystal display device, the electric field of the liquid crystal driving electrode and the common electrode enters the glass substrate and the color filter layer on the color filter side, so that the mobile ionic liquid contained in the glass substrate and the color filter layer is contained. The substance passes through the overcoat layer and elutes in the alignment film or the liquid crystal. These mobile ionic substances cause afterimages and abnormal pretilt angles, resulting in unevenness and markedly degrading image quality.

Further, unlike a conventional TN liquid crystal display device of the vertical electric field type, the color filter substrate of the horizontal electric field type is susceptible to static electricity because there is no transparent conductive film on the entire surface, and thus has been charged up. In such a case, there is a problem that poor alignment is caused.

The present invention has been made to solve these problems, and an object of the present invention is to provide a liquid crystal display device which is free from gradation inversion, has good viewing angle characteristics, and has good contrast without color shift. It is in. Furthermore, low-voltage driving ICs can be used, improving the yield of the liquid crystal process,
It is to lower the cost.

[0010]

Means for Solving the Problems In order to solve the above problems and achieve the above object, the present invention uses the following means. A scanning signal wiring and a video signal wiring on a substrate; a thin film transistor formed at each intersection of the scanning signal wiring and the video signal wiring; a liquid crystal driving electrode connected to the thin film transistor; A liquid crystal display device comprising: an active matrix substrate having a common electrode formed to face a drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In [Means 1], the liquid crystal driving electrode and the common electrode facing the liquid crystal driving electrode are bent in the alignment direction of the liquid crystal molecules, and the bent portion at the center of the pixel is bent in the bent direction. Each electrode sticks out, and in the periphery of the pixel, each electrode bends in the direction of the bent concave part, and the liquid crystal drive electrode and the liquid crystal drive The distribution of the electric field formed between the common electrode facing the electrode and the common electrode is set to be a distribution having the center of the pixel as a line-symmetric axis.

[Means 2] The liquid crystal driving electrode and the common electrode facing the liquid crystal driving electrode are bent at a pixel period with respect to the alignment direction of the liquid crystal molecules, and each of the pixels in each pixel is bent in the convex direction. The peripheral electrode is bent, and the electric field distribution formed by the liquid crystal driving electrode and the common electrode facing the liquid crystal driving electrode is a distribution with the scanning signal wiring as a line symmetric axis, or
The distribution was such that the video signal wiring was a line symmetric axis.

[Means 3] The liquid crystal does not contain a chiral dopant material so that the liquid crystal molecules can be rotated by the same rotational force in both the left rotation and the right rotation.

[Means 4] In the means 1 and 2, a part of the liquid crystal drive electrode is sandwiched by interposing an insulating film between the scanning signal wiring and the common electrode.

[Means 5] In a horizontal electric field type liquid crystal display device, a structure is adopted in which a common electrode and a liquid crystal drive electrode are separated by two or more insulating films.

[Means 6] In a horizontal electric field type liquid crystal display device, a structure is adopted in which a common electrode is arranged to bend over two rows so as to intersect with the scanning signal wiring.

[Means 7] In the means 6, the common electrodes intersecting the scanning signal wiring and being bent over two rows are separated into an odd group and an even group, and each of them is connected for driving an odd number common electrode. The electrodes were connected to the even-numbered common electrode driving connection electrodes.

[Means 8] In the means 7, the common electrodes are separated into an odd-numbered group and an even-numbered group, and each is connected to an odd-numbered common electrode driving connection electrode and an even-numbered common electrode driving connection electrode, respectively. To the liquid crystal drive electrodes facing the odd and even groups of common electrodes, respectively, and apply a video signal voltage waveform of the opposite phase to the common electrodes. Drive method.

[Means 9] In the means 6, the common electrodes arranged to bend over two rows intersecting with the scanning signal wiring are separately separated from each other.

[Means 10] In the means 9, common electrodes which are arranged to bend over two rows intersecting with the scanning signal wiring are separately separated from each other. A signal voltage is applied at an integral multiple of the frequency, the applied voltage polarity is changed for each field cycle, and the liquid crystal drive electrode facing the bent common electrode has a video signal voltage waveform in the opposite phase to the common electrode. Are applied to the driving method.

[Means 11] In a horizontal electric field type liquid crystal display device, thin film transistors are alternately connected to a liquid crystal drive electrode over two rows before and after one scanning signal line, and are opposed to the liquid crystal drive electrode. Some common electrodes have a structure arrangement that is separated and independent for each row.

[Means 12] In the means 11, a signal voltage is applied to a common electrode separated and independent for each row at a frequency which is an integral multiple of 1/2 of the field frequency, and the applied voltage polarity is changed for each field cycle. The driving method is such that a video signal voltage waveform having a phase opposite to that of the common electrode is applied to the liquid crystal driving electrode which is changed and opposed to the common electrode.

[Means 13] In the means 9 or 11, the three kinds of electrodes of the scanning signal wiring, the video signal wiring, and the common electrode are connected to the connecting electrodes for static electricity countermeasure on the outer periphery by the non-linear element for static electricity countermeasures. Structure.

[Means 14] In an active matrix substrate liquid crystal display device, the scanning signal wiring is formed of two layers of aluminum and a high melting point metal, and the high melting point metal is overlaid on the aluminum and the high melting point metal is covered. Aluminum oxide was formed on the unexposed side wall and on the portion where the aluminum near the side wall was exposed.

[Means 15] In a horizontal electric field type liquid crystal display device, after a passivation film such as a silicon nitride film, a silicon oxide film, or an aluminum oxide film is formed on the color filter layer, a flattening film is formed. A counter substrate having a structure in which an overcoat layer was formed on a passivation film was used.

[Means 16] In the means 15, a conductive electrode is formed in a mesh shape or a stripe shape on the overcoat layer formed on the passivation film,
This potential can be set near the intermediate value of the video signal voltage on the TFT substrate side.

[Means 17] In the means 15, the pattern width of the conductive electrodes formed in a mesh or stripe on the overcoat layer is made smaller than the width of the underlying BM (black mask).

[Means 18] In the means 1 or 2, the distance between the liquid crystal drive electrode and the common electrode is set to 1
Each pixel is not uniform, and is constituted by a combination of two or more kinds of distances between electrodes.

[0028]

When a horizontal electric field is applied within the pixel electrode (part of the liquid crystal driving electrode and the common electrode) as shown in FIGS. 31 and 32 by the above means 1 and 3, the liquid crystal molecules are removed inside the pixel electrode. It makes two kinds of rotational movements, left rotation and right rotation. As shown in FIGS. 2 and 4, in the conventional in-plane switching method, since only one rotation is performed, a color shift occurs in which the color changes depending on the viewing direction. Further, when the pretilt angle of the liquid crystal is large, the viewing angle characteristic is deviated, and the gray scale inversion in the halftone region is apt to occur. If two kinds of rotational movements, that is, left rotation and right rotation, become possible within one pixel, all of the above problems will be solved. However, if the rotational forces of the left rotation and the right rotation are not made equal, the movement of the liquid crystal is distorted at the central bent portion of the pixel electrode, causing a large disclination defect. Further, even in a portion where only the electric field in the peripheral portion of the pixel is deviated, the rotation of the liquid crystal becomes abnormal, and a disclination defect occurs. These alignment defects of the liquid crystal remain at the portion where the response speed is generated once at a minimum. This may be seen as an afterimage. The disclination defect portion leaks light even during black display, and significantly lowers the contrast. The use of the means 1 and 3 makes it possible to align the electric field around the pixel center and the periphery of the pixel in the direction of rotation of the liquid crystal, so that the occurrence of disclination defects can be completely suppressed and the decrease in contrast can be prevented. The afterimage due to the disclination defect does not completely occur.

By using the above means 2 and 3, even if the rotation direction of the liquid crystal molecules in one pixel is one direction, the rotation direction of the liquid crystal molecules in the entire screen is two kinds of rotations, left rotation and right rotation. Can be created. Due to this effect, the problem of color shift, the problem of grayscale inversion in the halftone area,
The problem of deviation of the viewing angle characteristics can all be solved. By aligning the electric field around the pixel in the rotation direction of the liquid crystal, it is possible to prevent the occurrence of a disclination defect. Therefore, it is possible to completely prevent the decrease in contrast and the occurrence of an afterimage.

By using the above-mentioned means 1, 2, 4, the storage capacity of the liquid crystal drive electrode can be increased, and the storage capacity is reduced even if the area of the common electrode and the liquid crystal drive electrode around the pixel is reduced. Problem can be solved. As a result, the aperture ratio of the pixel can be increased, and the light use efficiency can be improved.

By using the means 5, the short circuit at the overlapping portion of the common electrode and the liquid crystal drive electrode is drastically reduced, and the yield is remarkably improved. Defects due to dust and the like cannot be reduced to zero if only one insulating film is used for interlayer separation. Defects rarely overlap with each other in interlayer separation using two insulating films. Further, since the insulating film becomes thicker, the dielectric breakdown voltage at the step portion of the electrode becomes higher, so that a short circuit due to static electricity is drastically reduced. Since the overlapping portion between the common electrode and the liquid crystal driving electrode can be freely designed, the shape of the electric field distribution can be made so that the disclination of the liquid crystal does not occur. Therefore, light loss at the black level can be prevented, and an image with high contrast can be obtained.

By using the means 6, 7, and 8, it is possible to reduce the video signal voltage of the dot inversion driving method to less than half even in the liquid crystal display device of the horizontal electric field method. 5V
Since a driving video signal driving IC can be used,
The cost of the IC can be reduced. By reducing the video signal drive voltage to less than half the conventional voltage, the power consumption of the IC can be significantly reduced. Further, since the amplitude of the video signal voltage is less than half that of the related art, the driving capability of the thin film transistor hardly causes a difference between the even field and the odd field.
This makes it difficult for a DC bias to be applied to the liquid crystal, so that an afterimage does not occur. Because of the dot inversion drive, horizontal crosstalk, vertical crosstalk, and flicker do not occur.

By using the means 6, 9 and 10, the same effect as when the means 6, 7 and 8 are used can be obtained.
By separately separating the common electrodes and applying different drive voltage waveforms, the degree of freedom of the timing of changing the voltage waveform with respect to the scan signal voltage waveform is greatly expanded. Thus, even if the resistance value of the common electrode is increased by a factor of 10 or more, the problem of the drive timing does not occur. The degree of freedom of the material of the common electrode is increased, and the thickness of the electrode can be made very thin. Since the step of the common electrode is also reduced, a defect of the insulating film that covers the step is not generated, and the occurrence of short-circuit is reduced.

By using the above means 11, 12, the same effect as when using the above means 6, 9, 10 can be obtained.
In this case, since the common electrode does not cross the scanning signal line, the capacitance of the scanning signal line is reduced, and the resistance value of the scanning signal line can be slightly increased. Since there is no intersection, short-circuit between the common electrode and the scanning signal line does not occur. It is possible to improve the yield.

By using the above means 9, 11, and 13,
Even if the common electrodes are separated from each other, the charging time due to static electricity can be shortened, so that dielectric breakdown is less likely to occur, adhesion of dust during process work is reduced, and the yield can be greatly improved.

By using the means 14, even if inexpensive and low-resistance aluminum is used for the scanning signal wiring, side lock does not occur and the yield can be improved.

The provision of the above means 15, 16, 17 can prevent a mobile ionic substance such as sodium contained in the glass substrate from being eluted into the liquid crystal through the overcoat layer, and the afterimage problem can be prevented. Can be suppressed. Since a decrease in the specific resistance of the liquid crystal can be prevented, a highly reliable liquid crystal panel having a high charge retention rate can be manufactured. Since uniformity and lowering of contrast can be prevented, uniform and good halftone display is possible. Static electricity can also be prevented, and adhesion of dust is reduced.

By using the above means 1, 2, and 18, even if the alignment of the photomask is slightly deviated, it is possible to prevent the grayscale inversion, and to obtain a good image which has no viewing angle characteristic and is less likely to cause color shift. Obtainable.

[0039]

【Example】

[Embodiment 1] FIGS. 5, 6, 7, 8, 9, 10,
11 and 12 are a plan view and a sectional view of a unit pixel according to the present invention. The sectional views of FIGS. 5, 6, and 9 are shown in FIG. 11, and the sectional views of FIGS. 7, 8, and 10 are shown in FIG. The scan signal wiring is preferably made of an anodizable metal such as Al, but may be a pure metal or alloy such as Cr, Mo, Ti, W, Ta and Nb. A super-large display device has a two-layer structure or a three-layer structure using Cu or Al having a low electric resistance as a main material and the refractory metal or an alloy of the refractory metal. FIG.
In the case of FIGS. 6 and 9, the scanning signal wiring and the common electrode can be formed simultaneously in the same layer. However, since the scanning signal wiring and the common electrode are frequently short-circuited due to a pattern defect, FIGS. The scanning signal wiring and the common electrode were separated into different layers as shown in FIG. As a result, even if a pattern defect occurs, a short circuit does not occur, and the yield can be greatly improved. 7, 8,
In the case of FIG. 10, similarly, the video signal wiring and the common electrode are separated into different layers, so that even if a pattern defect occurs, a short circuit does not occur, so that the yield is improved. An amorphous silicon film layer (12) is formed on the scanning signal wiring after a gate insulating film (45) is formed, which is used as an active active layer of a transistor. A polysilicon film layer may be used instead of the amorphous silicon film. The same applies to a composite laminated film of a polysilicon film and an amorphous film. An n ⁺ amorphous silicon layer doped with an impurity such as phosphorus is formed on the active active layer. Next, a video signal wiring and a drain electrode are formed so as to overlap a part of the active active layer. FIG. 5, FIG. 6, FIG. 7, FIG.
In the case of FIGS. 9 and 10, the drain electrode and the liquid crystal drive electrode are formed simultaneously with the same metal material. As shown in FIG. 34, it is also possible to form a passivation film after the formation of the drain electrode and then form a drain through hole to electrically connect the drain electrode and the liquid crystal drive electrode. After forming the passivation film, in FIG. 11, an alignment film (14) made of polyimide is formed, and the surface is subjected to a rubbing treatment. Similarly, a rod-like liquid crystal molecule or a liquid crystal molecule (10) is provided between the opposing substrate (47) having an alignment film (43) having a rubbed surface formed on the surface thereof and the active matrix substrate.
The liquid crystal composition including ▼ is sealed, and a polarizing plate is arranged on the outer surfaces of the two substrates to complete the liquid crystal cell in the horizontal electric field direction.

FIG. 31 and FIG. 32 are basic conceptual diagrams of the present invention. FIG. 31 shows the layout of the liquid crystal drive electrodes and the common electrode when a positive dielectric anisotropic liquid crystal is used, and the relationship between the rubbing alignment axis direction and the electrodes. FIG. 32 shows the layout of the liquid crystal drive electrodes and the common electrode when a negative dielectric anisotropy liquid crystal (10) is used, and the relationship of the rubbing alignment axis direction to these electrodes. The conventional electrode shape arrangement has an electrode shape in which the center of the pixel is rotationally symmetric as shown in FIGS. 1 and 3, but in the case of the present invention, the electrode shape in which the central axis of the pixel is a line-symmetric axis. It becomes. In the bent portion at the center of the pixel, each electrode sticks out in the direction of the convex portion of the bend, and in the peripheral portion of the pixel, each electrode is bent in the direction of the concave portion of the bend. The number of bends may be one bend or two or more bends in one pixel as shown in FIGS. The orientation method may not be the rubbing method. An alignment method using a UV alignment film may be used. In the case of the present invention, color rotation does not occur in principle because the rotation direction of liquid crystal molecules exists in two directions in one pixel in the left and right directions. For this reason, in the conventional unidirectional rotating horizontal electric field type liquid crystal panel, the color shift could not be reduced without using a liquid crystal having a small refractive index anisotropy Δn. However, by using the electrode of the present invention, the value of Δn can be reduced. It can be set freely. Since Δn can be increased, the drive voltage can be reduced. The alignment film can also be selected without being influenced by the pretilt angle.

[Embodiment 2] FIGS. 33 and 34 show that the liquid crystal driving electrode and the common electrode are bent at the pixel period with respect to the alignment direction of the liquid crystal molecules, and the peripheral portion in each pixel is bent in the convex direction. The electrode is bent, and the electric field distribution formed by the liquid crystal driving electrode and the common electrode facing the liquid crystal driving electrode becomes a distribution with the scanning signal wiring as a line symmetric axis or a distribution with a video signal wiring as a line symmetric axis. FIG. 5 is a plan view of a unit pixel when the pixel is in the state. The same function as the unit pixel of the first embodiment is expressed by a set of two adjacent pixels. Although the electrode structure of Example 1 is necessary as a display for a computer, the electrode structures of FIGS. 33 and 34 are sufficient for displaying a moving image such as a television. FIGS. 33 and 34 show a structure in which the common electrode is arranged in parallel without intersecting with the scanning signal wiring.
This is the same arrangement as in FIGS. 5, 6, and 9 in the first embodiment. As shown in FIG. 7, FIG. 8, and FIG. 10, it is possible to have a structure arranged in parallel without intersecting the video signal wiring. Since the liquid crystal drive electrode and the common electrode in one pixel in FIG. 33 are not bent in one pixel, unlike FIGS. 5 and 6, the light transmittance can be increased.

[Embodiment 3] As described in Embodiments 1 and 2, when the rotational motion direction of the liquid crystal molecules in the horizontal electric field type liquid crystal display panel is simultaneously rotated in two directions, left and right, It is better not to include a chiral dopant material in the liquid crystal. When there is a difference between the left and right rotational driving forces, in a structure in which disclination occurs at the bent portion of the electrode as shown in FIGS. 5 and 7, the disclination grows in a region in the direction where the rotational force is weak. Image quality will be degraded. As the area of the disclination is enlarged, a decrease in contrast and an afterimage phenomenon are observed. Figure 6
As shown in FIG. 8, disclination can be prevented by designing the liquid crystal drive electrode and the common electrode so that they intersect even at a slight angle at the bent portion.

[Embodiment 4] FIGS. 7, 8, 10, and 3
6, FIG. 12 is a plan view and a cross-sectional view of a structure in which a part of a liquid crystal drive electrode is sandwiched between a scanning signal wiring and a common electrode through an insulating film. With this structure, the storage capacity of the liquid crystal drive electrode can be increased, so that the area of the common electrode and the liquid crystal drive electrode in the effective pixel can be reduced. As a result, the aperture ratio of the pixel can be increased. In the case of FIG. 36, the video signal wiring and the common electrode intersect each other through the passivation film 46, so that the passivation film 46 is 1.5 times as large as those of the structures of FIGS. Needs to be about twice as thick. By forming a passivation film of about 4000 to 6000 degrees twice using a plasma CVD apparatus, a short circuit due to a pinhole can be drastically reduced.

Embodiment 5 FIGS. 5, 6, 9, and 11
3A and 3B are a plan view and a cross-sectional view of a structure in which a common electrode and a liquid crystal drive electrode are separated by two or more insulating films. Glass substrate ▲ 1
First, a common electrode is formed on 1), and then a base insulating film 44 is deposited using a plasma CVD apparatus. Next, a scanning signal wiring is formed, and a gate insulating film
After depositing, a semiconductor layer １２12 ’and an n ⁺ amorphous silicon layer doped with impurities are continuously formed. The liquid crystal drive electrode and the video signal wiring are formed simultaneously using the same metal material. Passivation film on these 4
After depositing 6), a liquid crystal alignment film 14) is formed by flexographic printing. As can be seen from the cross-sectional view of FIG. 11, the common electrode and the liquid crystal drive electrode are separated from each other by two insulating films. This structure can be applied to the conventional electrode structure plan views FIGS. In the conventional case, since the scanning signal wiring and the common electrode are simultaneously formed on the same layer, the probability that the scanning signal wiring and the common electrode are short-circuited when a pattern defect due to dust or foreign matter occurs is extremely high, thereby reducing the yield. I was Further, since the common electrode and the liquid crystal driving electrode are insulated and separated only by the gate insulating film (45), if a pinhole is present, a short circuit occurs and this pixel becomes a point defect. According to the present invention, since the layers are separated by the two insulating films, the short circuit between the common electrode and the liquid crystal driving electrode is drastically reduced, the short circuit between the scanning signal wiring and the common electrode is drastically reduced, and a large improvement in the yield can be realized. .

[Embodiment 6] FIGS. 13 and 15 are plan views of a structure in which a common electrode is arranged to bend over two rows crossing a scanning signal wiring. Although they intersect in units of one pixel, they may intersect in units of two or more pixels. When the ideal dot inversion driving method is adopted, FIGS.
The arrangement is as shown in FIG. FIGS. 19 and 20 show opposite-phase voltage signal waveforms applied to the common electrodes separated into an odd-numbered group and an even-numbered group in accordance with the period of a scanning signal, and opposite to the odd-numbered and even-numbered common electrodes. Liquid crystal drive electrode
The common electrode is a drive voltage waveform diagram for applying video signal waveforms of opposite phases. In this driving method, horizontal crosstalk does not occur and a good image can be obtained. By applying a voltage having a phase opposite to that of the video signal waveform to the common electrode, a large voltage can be applied to the liquid crystal phase, so that the amplitude of the video signal drive is smaller than that of the conventional dot inversion drive in which the common electrode potential is fixed. / 2 or less. As a result, an inexpensive IC driven at 5 V can be used.
own is possible.

[Embodiment 7] FIGS. 14 and 16 are plan views of a structure in which the common electrodes intersecting the scanning signal wiring and being bent over two rows are separately separated.
Three types of electrodes, a common electrode separately separated from the scanning signal wiring and the video signal wiring, are connected to the static electricity countermeasure connection electrodes on the outer peripheral portion by static electricity non-linear elements. FIG.
FIG. 22 shows an image signal voltage waveform having a phase opposite to that of the common electrode applied to the liquid crystal drive electrode facing the bent common electrode by changing the applied voltage polarity to the separately separated common electrode for each field period. FIG. 7 is a diagram of driving voltage waveforms respectively applied. By separately separating the common electrodes and applying a unique voltage waveform as in the present invention, the condition regarding the timing of the polarity change of the common electrode becomes very gentle. Before the scanning signal wiring is turned on, the polarity may be changed in accordance with the scanning signal wiring several lines before. The switching voltage waveform may change slowly, and the degree of freedom in selecting the metal material for the common electrode is greatly expanded. This eliminates the problem of the wiring resistance of the common electrode. FIGS. 21 and 22 show the most basic driving waveforms of the common electrode. If the polarity of the potential of the common electrode changes every field period, the driving waveform is sufficient. The voltage waveform until the next field polarity change occurs is completely free and the frequency is not limited.

[Embodiment 8] FIG. 17 shows that the common electrode is divided into an odd group and an even group, and voltage signal waveforms having opposite phases are applied in accordance with the scanning signal period. A video signal waveform having a phase opposite to that of the common electrode is applied to the liquid crystal drive electrode facing the electrode. Unlike the sixth embodiment, the driving method is such that two scanning signal lines are simultaneously turned on. Even in this structure, odd-numbered and even-numbered video signal wirings apply video signal voltages having different polarities.
Images without crosstalk can be realized. Since a delta arrangement can be realized as the arrangement of the colors of the color filters, an image with good color mixture can be obtained.

Ninth Embodiment FIG. 18 is a plan view of a structure in which common electrodes are separately separated. 3 of common electrodes separately separated from the scanning signal wiring and the video signal wiring, respectively.
The kinds of electrodes are connected to the connection electrodes for static electricity countermeasures on the outer periphery by non-linear elements for static electricity countermeasures. In the case of the structure shown in FIG. 18, unlike the seventh embodiment, two scanning signal lines are simultaneously turned on.
Drive system. The operation principle can be almost the same as that of the seventh embodiment.

[Embodiment 10] FIGS. 28 and 35 show that thin film transistors are alternately connected to a liquid crystal drive electrode over two rows before and after one scanning signal line, and face the liquid crystal drive electrode. FIG. 4 is a plan view of a structure in which common electrodes are separated and independent for each row. 29 and 30
Applies a signal voltage to the common electrode separated and independent for each row at a period twice as long as the field period, changes the applied voltage polarity every field period, and faces the liquid crystal driving electrode facing the common electrode. FIG. 3 is a drive voltage waveform diagram for applying a video signal voltage waveform having a phase opposite to that of the common electrode. The operation principle is the same as in the seventh embodiment.

[Embodiment 11] FIG. 23 is a sectional view when a conventional aluminum electrode is used as a scanning signal wiring. High melting point metal to prevent hillock of aluminum (29)
Is used as a cap metal. When the length of the inclined surface of the aluminum side wall is increased by 1 μm or more, hillocks are generated from the side wall. In order to prevent this, there is a method of mixing a metal such as neodymium in an amount of about 1 to 2 atomic percent. However, it is very difficult to make an aluminum alloy target over a large area and it is almost impossible to make a uniform composition. The use of pure aluminum as the scanning signal wiring is very important in producing a large-screen liquid crystal display panel. In the present invention, in order to prevent side hillocks of pure aluminum, aluminum oxide is formed on the side walls of aluminum by using a high-temperature steam oxidation method. FIG. 24 is a sectional view thereof. As another method, side hillocks can be prevented by ion-implanting oxygen ions, nitrogen ions, phosphorus ions, and the like into the side walls of the refractory metal and aluminum using ion implantation technology.

[Embodiment 12] FIG. 25 is a cross-sectional view of a color filter substrate of an in-plane switching mode liquid crystal display device. A BM (black mask) is formed on a glass substrate, and then a color filter layer is formed. 0.1 ~ for glass substrate
About 1.0% of alkali metal oxides are mixed.
Furthermore, pigments and dyes in the color filter layer contain many impurities, and these mobile ionic substances have a property of moving in the direction of an electric field when an electric field is present. As the overcoat layer (41) for flattening, an organic material is mainly used, but this film has no ability to prevent the electric field movement of mobile ions. As a film often used as a passivation film for mobile ions,
There are a silicon nitride film, a silicon oxynitride film, and an aluminum oxide film. In the present invention, as shown in FIG. 25, these passivation films are formed on a color filter layer using a plasma CVD technique or a sputtering technique to prevent mobile ions from moving to the liquid crystal layer or the alignment film surface. doing. With this structure, even if a horizontal electric field acts on the color filter layer or the glass substrate, the outflow of mobile ions can be prevented by the passivation film (40). This eliminates the problem of poor alignment of the alignment film and the problem of afterimage.

[Embodiment 13] FIGS. 26 and 27 are a sectional view and a plan view of a color filter substrate of a liquid crystal display device of an in-plane switching mode. During the rubbing process in the liquid crystal cell process, static electricity is generated on the alignment film, causing various troubles. In the invention, the overcoat layer # 41
▼ Conductive electrodes are formed in a mesh or stripe shape on the top and this potential is set near the middle value of the video signal voltage on the TFT substrate side, so that the influence of the external static electric field is cut off. Yes. By making the width of the conductive electrode on the overcoat layer smaller than the BM width, even if the alignment accuracy of the color filter substrate and the TFT substrate is poor, the liquid crystal drive electrode of the TFT substrate is not adversely affected. I have.

[Embodiment 14] As shown in FIG. 5, the distance between the liquid crystal drive electrode and the common electrode is not uniform in one pixel, but is formed by a combination of two or more types of electrode distance. By increasing the distance between the electrodes closest to the video signal wiring, the influence of the video signal wiring can be reduced, and the vertical stroke can be reduced. When combined with the bent electrode structure of the present invention, the best image with no color shift and no crosstalk can be obtained.

[0054]

According to the present invention, firstly, it is possible to obtain an image having good viewing angle characteristics, in which there is no grayscale inversion of the image and no color shift occurs when viewed from anywhere. Secondly, it is possible to produce a highly reliable and high-contrast image display device in which disclination does not occur and afterimages do not occur. Third,
Since an inexpensive 5 VIC can be used as the video signal driving IC and a conventional liquid crystal member can be used, an image display device with low cost and high productivity can be provided. Fifth, it is possible to realize a super large large screen liquid crystal display device using a conventional metal material.

[Brief description of the drawings]

FIG. 1 is a plan view of a conventional electrode structure for preventing occurrence of disclination.

FIG. 2 is an alignment diagram of a conventional linear pixel electrode and a positive dielectric anisotropic liquid crystal.

FIG. 3 is a plan view of a conventional electrode structure for preventing occurrence of disclination.

FIG. 4 is an orientation diagram of a conventional linear pixel electrode and a negative dielectric anisotropic liquid crystal.

FIG. 5 is a plan view of a unit pixel of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 6 is a plan view of a unit pixel of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 7 is a plan view of a unit pixel of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 8 is a plan view of a unit pixel of a thin film semiconductor substrate of an in-plane switching type according to the present invention.

FIG. 9 is a plan view of a unit pixel of a thin film semiconductor substrate of an in-plane switching method according to the present invention.

FIG. 10 is a plan view of a unit pixel of a thin film semiconductor substrate of an in-plane switching type according to the present invention;

FIG. 11 is a cross-sectional view of a unit pixel of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 12 is a sectional view of a unit pixel of a thin film semiconductor substrate of an in-plane switching type according to the present invention;

FIG. 13 is a plan view of a pixel array of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 14 is a plan view of a pixel array of a thin film semiconductor substrate of an in-plane switching type according to the present invention.

FIG. 15 is a plan view of a pixel array of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 16 is a plan view of a pixel array of the in-plane switching semiconductor substrate of the present invention.

FIG. 17 is a plan view of a pixel array of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 18 is a plan view of a pixel array of a thin film semiconductor substrate of an in-plane switching type according to the present invention.

FIG. 19 is a drive voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 20 is a driving voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 21 is a driving voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 22 is a driving voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 23 is a sectional view of a conventional scanning signal wiring.

FIG. 24 is a sectional view of a conventional scanning signal line.

FIG. 25 is a sectional view of a color filter for an in-plane switching mode liquid crystal display device according to the present invention.

FIG. 26 is a sectional view of a color filter for an in-plane switching mode liquid crystal display device according to the present invention.

FIG. 27 is a plan view of a color filter for an in-plane switching mode liquid crystal display device according to the present invention.

FIG. 28 is a plan view of a pixel array of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 29 is a drive voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 30 is a driving voltage waveform diagram of the in-plane switching mode liquid crystal display device of the present invention.

FIG. 31 is a plan view of the structure of the electrode for preventing the occurrence of disclination according to the present invention and the orientation diagram of the positive dielectric anisotropic liquid crystal.

FIG. 32 is a plan view of the structure of the electrode for preventing disclination occurrence according to the present invention and the orientation diagram of the negative dielectric anisotropic liquid crystal.

FIG. 33 is a plan view of a unit pixel of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 34 is a plan view of a unit pixel of a thin film semiconductor substrate of an in-plane switching type according to the present invention;

FIG. 35 is a plan view of a pixel array of a lateral electric field type thin film semiconductor substrate of the present invention.

FIG. 36 is a plan view of a unit pixel of a thin film semiconductor substrate of an in-plane switching type according to the present invention;

[Explanation of symbols]

1—scanning signal wiring 2—video signal wiring 3—common electrode 4—liquid crystal drive electrode 5—thin film transistor (TFT) element 6—liquid crystal alignment axis on TFT substrate 7—positive dielectric anisotropy Angle at which liquid crystal molecules (P-type liquid crystal molecules) intersect with pixel electrodes (common electrode and liquid crystal drive electrode) 8- Negative dielectric anisotropy liquid crystal molecules (N-type liquid crystal molecules) and pixel electrodes (common electrode and liquid crystal drive electrode) Angle at which the electrodes intersect 9—Positive dielectric anisotropic liquid crystal molecules (P-type liquid crystal molecules) 10—Negative dielectric constant anisotropic liquid crystal molecules (N-type liquid crystal molecules) 11—TFT side glass substrate 12 --Semiconductor layer 13--N ⁺ -amorphous silicon layer doped with impurities 14--Alignment film 15--Odd-numbered common electrode driving connection electrode 16--Even-numbered common electrode driving connection electrode 17--Electrostatic countermeasure Element 18—scan signal wiring lead-out terminal 19—Video signal wiring lead terminal 20—Common electrode lead terminal 21—Electrostatic countermeasure connection electrode 22—Nth scan signal wiring drive waveform 23—Odd number common electrode drive waveform 24—Odd number video signal waveform 25- (n + 1) -th scan signal wiring drive waveform 26-even-number video signal waveform 27-even-number common electrode drive waveform 28-aluminum (or aluminum alloy) scan signal wiring 29-high melting point metal (or high) Melting point metal silicide compound, high melting point metal compound) 30—side wall aluminum oxide 31— (n−1) th scan signal wiring drive waveform 32—mth common electrode drive waveform (linear connection type) 33—mth Common electrode drive waveform 34-(m + 1) common electrode drive waveform (straight connection type) 35-Electrostatic discharge connection electrode lead terminal 36-(m-1) common electrode Driving waveform 37-(m + 1) th common electrode driving waveform 38-Black mask 39-Color filter layer 40-Color filter passivation film 41-Flattening film 42-Electrostatic measures conductive film (or semiconductor) Film—43—Color filter-side liquid crystal alignment film 44—Base insulating film 45—Gate insulating film 46—TFT passivation film 47—Color filter-side glass substrate 48—Drain through hole

Claims (18)

[Claims] A scanning signal line and a video signal line on a substrate;
A thin film transistor formed at each intersection of the scanning signal wiring and the video signal wiring; a liquid crystal drive electrode connected to the thin film transistor; and a common electrode formed at least partially facing the liquid crystal drive electrode. A liquid crystal display device comprising: an active matrix substrate having: a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. The opposing common electrode is bent with respect to the alignment direction of the liquid crystal molecules, each electrode sticks out in the bent convex direction at the central portion of the pixel, and each electrode protrudes in the pixel peripheral portion. The electric field distribution formed by the liquid crystal driving electrode and the common electrode facing the liquid crystal driving electrode, in which the electrode bends in the direction of the concave portion of the bend. A liquid crystal display device, characterized in that has a distribution in which the center pixel line-symmetric axis. 2. A scanning signal wiring and a video signal wiring on a substrate,
A thin film transistor formed at each intersection of the scanning signal wiring and the video signal wiring; a liquid crystal drive electrode connected to the thin film transistor; and a common electrode formed at least partially facing the liquid crystal drive electrode. A liquid crystal display device comprising: an active matrix substrate having: a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. The common electrode is bent at the pixel period with respect to the orientation direction of the liquid crystal molecules, and the peripheral electrodes in each pixel are bent in the convex direction of the bend, facing the liquid crystal drive electrode and the liquid crystal drive electrode. The distribution of the electric field formed by the common electrode is the distribution with the scanning signal wiring as the axis of symmetry, or the distribution of the video signal wiring with the axis of symmetry. The liquid crystal display device, characterized in that it has become the distribution. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal layer sandwiched between the active matrix substrate and the opposing substrate does not contain a chiral topant material. 4. A liquid crystal display device according to claim 1, wherein a part of the liquid crystal driving electrode is sandwiched between the scanning signal wiring and the common electrode via an insulating film. 5. A thin film transistor formed on a substrate at each intersection of a scanning signal wiring, a video signal wiring, the scanning signal wiring and the video signal wiring, a liquid crystal drive electrode connected to the thin film transistor, and at least a part thereof. Comprises an active matrix substrate having a common electrode formed so as to face the liquid crystal driving electrode, a counter substrate facing the active matrix substrate, and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. A liquid crystal display device having a structure in which a common electrode and a liquid crystal drive electrode are separated by two or more insulating films. 6. A thin film transistor formed on a substrate at each intersection of a scanning signal wiring, a video signal wiring, the scanning signal wiring and the video signal wiring, and a liquid crystal drive electrode connected to the thin film transistor; A liquid crystal comprising: an active matrix substrate having a common electrode formed to face the liquid crystal drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. 2. A liquid crystal display device according to claim 1, wherein the common electrode intersects the scanning signal wiring and is bent over two rows. 7. A common electrode according to claim 6, wherein the common electrodes intersecting the scanning signal wiring and bent over two rows are separated into an odd group and an even group, and each is divided into an odd number common electrode. A liquid crystal display device characterized in that it is connected to a driving connection electrode and an even-numbered common electrode driving connection electrode. 8. The method according to claim 7, wherein the common electrodes are divided into an odd group and an even group, and each is connected to an odd-numbered common electrode driving connection electrode and an even-numbered common electrode driving connection electrode. A signal electrode of opposite phase is applied to each of the two electrode groups at a scanning line signal drive period, and a video signal of opposite phase to the common electrode is applied to the liquid crystal drive electrodes facing the common electrodes of the odd and even groups. A liquid crystal display device characterized by applying voltage waveforms. 9. A liquid crystal display device according to claim 6, wherein the common electrodes intersecting the scanning signal wiring and being bent over two rows are separately separated from each other. 10. The common electrode according to claim 9, wherein common electrodes intersecting the scanning signal wiring and bent over two rows are separately separated from each other, and separated into independent common electrodes. The signal voltage is applied at twice the cycle, the applied voltage polarity is changed every field cycle, and the liquid crystal drive electrode facing the bent common electrode is connected to the video signal voltage of the opposite phase with the common electrode. A liquid crystal display device to which a waveform is applied. 11. A thin film transistor formed on a substrate at each intersection of a scanning signal wiring, a video signal wiring, the scanning signal wiring and the video signal wiring, a liquid crystal driving electrode connected to the thin film transistor, and at least a part thereof. A liquid crystal comprising: an active matrix substrate having a common electrode formed to face the liquid crystal drive electrode; a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In the display device, before and after the one scanning signal line
A liquid crystal display device characterized by a structure in which thin film transistors are alternately connected to liquid crystal drive electrodes over rows, and common electrodes facing the liquid crystal drive electrodes are separated and independent for each row. 12. A method according to claim 11, wherein a signal voltage is applied to a common electrode separated and independent for each row at a period twice as long as a field period, and the applied voltage polarity is changed for each field period. A liquid crystal display device wherein a video signal voltage waveform having a phase opposite to that of a common electrode is applied to a liquid crystal drive electrode which is changed and opposed to the common electrode. 13. The method according to claim 9, wherein the scanning signal wiring, the video signal wiring, and the common electrode are connected to each other.
A liquid crystal display device comprising a structure in which different kinds of electrodes are connected to a connection electrode for static electricity countermeasures on an outer peripheral portion by a non-linear element for static electricity countermeasures. 14. An active matrix substrate on which a thin film transistor is formed, a counter substrate facing the active matrix substrate, and a liquid crystal display device sandwiched between the active matrix substrate and the counter substrate, wherein the scanning signal wiring is made of aluminum and high. Formed from two layers of melting point metal, aluminum oxide was formed on the side walls where aluminum is covered with high melting point metal and where high melting point metal is not covered or where aluminum near the side walls is exposed A liquid crystal display device characterized by the above-mentioned. 15. A scanning signal wiring and a video signal wiring on a substrate; a thin film transistor formed at each intersection of the scanning signal wiring and the video signal wiring; and a liquid crystal drive electrode connected to the thin film transistor; Comprises an active matrix substrate having a common electrode formed so as to face the liquid crystal driving electrode, a counter substrate facing the active matrix substrate, and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. In a liquid crystal display device, a passivation film such as a silicon nitride film, a silicon oxynitride film, or an aluminum oxide film is formed on a color filter layer formed on the counter substrate, and then an overcoat layer for planarization is formed on the passivation film. A liquid crystal display device characterized by the structure formed above. 16. A method according to claim 15, wherein a conductive electrode is formed in a mesh shape or a stripe shape on the overcoat layer formed on the passivation film, and this potential is applied to the TFT substrate side. A liquid crystal display device characterized by being set near an intermediate value of a video signal voltage. 17. A pattern according to claim 15, wherein the pattern width of the conductive electrode formed in a mesh or stripe on the overcoat layer is smaller than the width of the underlying BM (black mask). A liquid crystal display device characterized by the above-mentioned. 18. The liquid crystal display according to claim 1, wherein the distance between the liquid crystal driving electrode and the common electrode is not uniform within one pixel, and the distance between two or more kinds of electrodes is not uniform within one pixel. A liquid crystal display device characterized by being formed in combination.