JP2003215620A - Liquid crystal display and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display which can be made fast in the response of halftone display and increased in field angle. <P>SOLUTION: An IPS liquid crystal display comprises a 1st transparent substrate 1 where TFTs are formed, an opposite 2nd transparent substrate 11, and liquid crystal 17 which are held between those substrates and is characterized by that the 1st transparent substrate has gate lines 2 and data lines 6 crossing each other at right angles, TFTs 4 provided at wiring intersection parts, and pixel electrodes 7 arranged alternately along the width and a common electrode 3 and the 2nd transparent substrate 11 has a black matrix 12 having a specified opening, a color layer 13, and a flattened film 14 covering them on itself. A hollow 23 which is sectioned as specified is formed on the flattened film 14, etc., and then the gap between the opposite substrates is made different by the hollow 23 to continuously vary a threshold voltage in pixels, and thus panel transmissivity is made large and a response characteristic of halftones is improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display in a plane substantially parallel to a substrate by a voltage applied between a pixel electrode formed on a TFT substrate and a common electrode. Driven IPS (In-Plane Switchi
ng) type liquid crystal display device and a manufacturing method thereof.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device using a thin film transistor (hereinafter abbreviated as TFT) as a switching element of a pixel has a high quality image.
Widely used as a monitor for space-saving desktop computers. Generally, the operation mode of a liquid crystal display device includes a twisted nematic (TN) system in which a director of aligned liquid crystal molecules is rotated in a direction perpendicular to a glass substrate.
There is an IPS method in which the glass substrate is rotated in a direction parallel to the glass substrate.

In the IPS type liquid crystal display device, pixel electrodes and common electrodes which are parallel to each other are alternately formed on a first transparent substrate which forms a TFT, and a voltage is applied between them to make them parallel to the substrate surface. By forming a different electric field, the direction of the director of the liquid crystal is changed, thereby controlling the amount of transmitted light. Therefore, in this display method, since the director rotates in the plane of the substrate, the relationship between the amount of transmitted light and the applied voltage is large when viewed from the direction of the director and when viewed from the normal direction of the substrate as in the case of the TN method. The problem of being different does not occur, and a good image can be obtained from a very wide viewing angle.

In such an IPS system, the liquid crystal layer is homogeneously aligned, sandwiched by two polarizing plates whose polarization axes are orthogonal to each other, and one polarization axis is made equal to the alignment direction of the liquid crystal molecules, whereby a voltage is applied. Black display with no voltage applied,
In general, a liquid crystal molecule is twist-deformed in the direction of an electric field to produce white display by applying a voltage between the pixel electrode and the common electrode. With this method, the luminance during black display can be stably lowered. It is widely used because it can be done.

However, in the conventional IPS type liquid crystal display device, as shown in FIG. 15, the pixel electrode 7 and the common electrode 3 are linearly formed, and the liquid crystal molecules rotate in only one direction. There is a problem in that coloring occurs when viewed from an oblique direction. As a method for solving this problem, a method of bending the shapes of the pixel electrode 7 and the common electrode 3 in one pixel into a V shape is disclosed in Japanese Patent Laid-Open No. 9-31.
It is described in Japanese Patent No. 1334, etc.

The above technique will be described with reference to FIG. 13A and 13B are views showing the structure of a conventional IPS liquid crystal display device, in which FIG. 13A is a plan view and FIG.
It is sectional drawing in the A'line. This liquid crystal display device is
First transparent substrate 1 on which FT is formed and second transparent substrate 1 on which a color filter (Color filter: CF) is formed
1 and a liquid crystal 17 sandwiched therebetween, a gate electrode 2 and a data line 6 are formed on the first transparent substrate 1 substantially orthogonal to each other, and TFTs 4 are formed in a matrix at intersections of these.
Are arranged. Further, in each pixel, pixel electrodes 7 and common electrodes 3 which are bent in a V shape and are parallel to each other are alternately formed. In addition, on the second transparent substrate 11,
Black matrix 12 and R to block excess light
A color layer 13 for performing color display of three colors of GB and a flattening film 14 that covers these are formed.

An alignment film 18 is applied to the surfaces of the first transparent substrate 1 and the second transparent substrate 11, and a liquid crystal 17 is sandwiched between the two substrates. It is homogeneously aligned substantially parallel to the extending direction of the line 6. In addition, polarizing plates 16a and 16b are provided on the outer sides of both substrates.
Is attached, the polarization axes of both polarizing plates are orthogonal to each other, and one polarization axis is set parallel to the alignment direction of the liquid crystal. And
By writing a potential to the pixel electrode 7 through the TFT 4 and applying a lateral electric field between the pixel electrode 7 and the common electrode 3,
The liquid crystal 17 is twisted in a plane parallel to the substrate to control the display.

According to this method, when a voltage is applied between the pixel electrode 7 and the common electrode 3, as shown in FIG.
Electric fields are generated in different directions in the two regions sandwiching the bent portion of the V-shape, so that the liquid crystal molecules are twisted in two directions. Then, when viewed from the diagonal direction in the white display state, coloring of different colors occurs in the two areas, and as a result of compensating each other, coloring is reduced.

[0009]

[Patent Document 1] Japanese Unexamined Patent Publication No. 9-313334 (No. 2-
(Page 4, Figure 1)

[0010]

As described above, in the IPS type liquid crystal display device, the pixel electrode 7 and the common electrode 3 are formed in a V-shape, so that the viewing angle is considerably wide and the color is colored. However, in the IPS type liquid crystal display device, it is necessary to form the pixel electrode 7 and the common electrode 3 so as to keep the aperture ratio of the pixel region large. Therefore, both electrodes are densely formed. Cannot be done, and the interval between both electrodes cannot be narrowed. Therefore, in order to increase the electric field, the applied voltage must be increased, resulting in an increase in power consumption. On the other hand, when the applied voltage is small, the electric field becomes small, so that the response of the liquid crystal 17 cannot be accelerated. There is a problem.

As a method of solving this problem, there is a method of using a liquid crystal 17 having a low viscosity, which makes it possible to increase the response speed of white display. The electric field is small, and the response becomes about twice slower than that in white display. This problem will be described with reference to FIG. FIG. 14 is a diagram showing the correlation between the transmittance and the response of the panel with respect to the voltage applied to the liquid crystal, the broken line shows the correlation between the applied voltage and the panel transmittance, and the solid line shows the correlation between the applied voltage and the response. .

As shown in FIG. 14, the panel transmittance is such that as the voltage applied to the liquid crystal is increased, the alignment direction of the liquid crystal is twisted in the direction of the electric field so that light is easily transmitted. Each time twisted, the transmittance becomes maximum (white display state). Further, when the applied voltage is large, the liquid crystal molecules are likely to rotate, so that the response gradually becomes faster as the applied voltage increases. Here, since the voltage applied to the liquid crystal in the halftone display area is smaller than that in the white display state,
The response becomes slower than when white is displayed.

Generally, the threshold voltage Vth, which is the lowest voltage for the liquid crystal to start moving, is the distance L between the pixel electrode 7 and the common electrode 3, the effective cell gap d, the twist elastic constant K22 of the liquid crystal 17, and the liquid crystal 17. It is expressed as follows using the dielectric anisotropy Δε of

Vth = π · L / d × (K22 / ε0Δε) ^1/2 · (1)

That is, since the electric field strength decreases as the electrode spacing L increases, the threshold voltage Vth increases. On the other hand, the liquid crystal becomes easier to rotate as the cell gap d increases, and the threshold voltage Vth tends to decrease. . Therefore, in order to speed up the response of the liquid crystal, it suffices to reduce the electrode interval L and increase the cell gap d.

However, if the electrode distance L between the pixel electrode 7 and the common electrode 3 is made narrower or the cell gap is made larger uniformly, Vth becomes smaller, but the response in the halftone in the low voltage region is still accelerated. I can't
Further, if the electrode interval L is reduced, the area occupied by the electrodes in the pixel region increases, and the aperture ratio decreases.

The present invention has been made in view of the above problems, and its main purpose is to provide a liquid crystal display device and a method of manufacturing the same capable of accelerating the response of halftone display and increasing the panel transmittance. To provide.

[0018]

In order to achieve the above object, the present invention has a pair of opposed substrates and a liquid crystal sandwiched between the pair of substrates, and at least on the first substrate. Is a plurality of gate lines and a plurality of data lines that are substantially orthogonal to each other, a pixel electrode and a common electrode that are alternately formed in each pixel surrounded by the gate line and the data line, and insulation that covers each electrode. A black matrix having a predetermined opening, a color layer, and a flattening film covering the black matrix and the color layer on the second substrate,
In the IPS type liquid crystal display device, the liquid crystal oriented in the extending direction of the data line is controlled in a plane substantially parallel to the substrate by a voltage applied between the pixel electrode and the common electrode. At least one of the film and the flattening film is formed with a recess having a predetermined cross-sectional shape, and the recess forms a region having a different gap between the opposing substrates in the pixel region.

In the present invention, the recess is formed so as to extend in a direction parallel to the gate line passing through the center of the pixel, and regions having different gaps are lined with a line connecting the vertices of the recess as an axis. The recess may be formed symmetrically, or the recess may be formed so that a line connecting the vertices of the recess extends along the longitudinal direction of the pixel electrode or the common electrode.

Further, the present invention has a pair of opposed substrates and a liquid crystal sandwiched between the pair of substrates, and one of the pair of substrates has a black matrix having a predetermined opening and a color matrix. A layer, a plurality of gate lines and a plurality of data lines substantially orthogonal to each other, a pixel electrode and a common electrode alternately formed in each pixel surrounded by the gate line and the data line, the black matrix and the At least an interlayer film covering the color layer and an insulating film covering each of the electrodes,
In an IPS type liquid crystal display device, the liquid crystal oriented in the extending direction of the data line is controlled in a plane substantially parallel to the substrate by a voltage applied between the pixel electrode and the common electrode, A recess having a predetermined cross-sectional shape is formed in the interlayer film or the insulating film, and a region having a different gap between the opposing substrates is formed in the pixel region by the recess.

In the present invention, the color layer is divided and formed in the pixel, and the pixel electrode and the common electrode are formed in the same layer as the color layer so as to fill the space between the divided color layers. The recess may be formed in the interlayer film or the insulating film due to a difference in film thickness between the color electrode and the pixel electrode and the common electrode.

Further, in the present invention, the alignment film formed on the liquid crystal holding surface side of the pair of substrates is a film formed by offset printing using a material having a viscosity of 30 cp or more. You can also

Further, the present invention is a method for manufacturing the above-mentioned liquid crystal display device, wherein the flattening film or the interlayer film is formed by using an ultraviolet curable material as the flattening film or the interlayer film. After that, by locally irradiating with ultraviolet rays, a recess having a predetermined cross-sectional shape is formed.

In the present invention, an ultraviolet curable resin made of resist or polyimide may be used as the ultraviolet curable material, and ultraviolet rays may be locally irradiated by an ultraviolet cut filter.

As described above, according to the present invention, the region having a small threshold voltage of the liquid crystal and the region having a large threshold voltage of the liquid crystal can be continuously formed in one pixel, and the voltage applied to the liquid crystal can be formed in the region having the small threshold voltage. Even in a low halftone, the panel transmittance can be increased and the response can be speeded up.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] In the first embodiment of the present invention, a first transparent substrate on which a TFT is formed is opposed to a second transparent substrate, and a second transparent substrate is sandwiched between those substrates. And a pixel electrode formed by alternately arranging in a width direction on the first transparent substrate, the gate line and the data line extending orthogonally to each other, the TFT provided at the wiring intersection, And a common electrode, and an insulating film covering these electrodes,
The second transparent substrate includes a black matrix that blocks light other than the pixel region, a color layer that performs color display, and a flattening film that covers the black layer, and the first transparent substrate is provided in a portion corresponding to the pixel region.
The insulating film of the transparent substrate or the flattening film of the second transparent substrate is provided with a recess having a predetermined shape, and the width of the cell gap between the first and second transparent substrates is set within the pixel. By lowering Vth in a wide area, the response characteristic in the halftone is improved.

[Embodiment 2] In the fourth embodiment of the present invention, the second transparent substrate facing the first transparent substrate on which the TFT is formed and the second transparent substrate sandwiched between them. The first transparent substrate, which is made of liquid crystal, has a black matrix that blocks light other than the pixel region, a color layer that performs color display, and gate lines and data lines that extend orthogonally to each other.
A first portion of a portion corresponding to a pixel region, which includes a TFT provided at a wiring intersection, a pixel electrode and a common electrode alternately arranged in the width direction, and an insulating film covering these electrodes or a color layer, is provided. By providing a recess of a predetermined shape in the insulating film of the transparent substrate, the width of the cell gap between the first and second transparent substrates is provided in the pixel, and the Vth of the portion having the wide cell gap is lowered, the intermediate tone is reduced. It improves the response characteristics.

[0028]

EXAMPLES Examples of the present invention will be described with reference to the drawings in order to describe the above-described embodiments of the present invention in more detail.

[Embodiment 1] First, an IPS type liquid crystal display device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. 1 and 2 are views showing the structure of the liquid crystal display device according to the first embodiment, where (a) is a plan view and (b) is a cross-sectional view taken along line BB ′ of (a). . Further, FIG. 3 is a diagram for explaining the effect of this embodiment, and is a diagram showing the correlation between the voltage applied to the liquid crystal and the panel transmittance and response. Moreover, FIG. 4 is a process cross-sectional view showing a method of forming a depression. In this embodiment, as a method of speeding up the response of the liquid crystal in the halftone, the cell gap is widened instead of changing the electrode interval.

First, the structure of the IPS liquid crystal display device of this embodiment will be described with reference to FIG. 1. On the first transparent substrate 1 side, a gate electrode 2 and a data line 6 are formed substantially orthogonal to each other. The TFTs 4 are arranged in a matrix at these intersections to form one pixel. A pixel electrode 7 and a common electrode 3 are formed in each pixel, and the pixel electrode 7 is T
It is connected to FT4. Here, both electrodes may have a linear shape or a shape having a bending point as shown in the prior art.

Further, on the second transparent substrate 11, a black matrix 12 for blocking extra light on the gate electrodes 2, the data lines 6 and between these and the pixel display portion,
Although the color layer 13 for performing color display of three colors of RGB and the flattening film 14 are formed so as to cover the color layer 13, in this embodiment, a part of the flattening film 14 has a predetermined shape. The feature is that the depression 23 is formed. That is, the recess 23 is formed in the central portion of the pixel so as to extend in the direction of the gate electrode 2, and the depth of the recess 23 is changed within one pixel, whereby the first transparent substrate 1 and the second transparent substrate 11 are formed. The cell gap with is changing.

Considering the relationship between the cell gap and the response of the liquid crystal, the threshold voltage Vth, which is the lowest voltage for driving the liquid crystal, is inversely proportional to the cell gap d, as shown in Equation 1, and the cell gap d Becomes larger, the liquid crystal molecules tend to rotate, and the threshold voltage Vth becomes smaller.
The decrease in the threshold voltage Vth means that the liquid crystal rotates with a small voltage, and the response in the halftone becomes faster. That is, the response can be improved also by changing the cell gap, similarly to the case where the distance between the pixel electrode 7 and the common electrode 3 is changed. In this embodiment, a region 19a having a large cell gap is formed so as to extend in the direction of the gate electrode 2 through the central portion of the pixel, and the cell gap becomes gradually smaller as it gets closer to the gate electrode 2 (see 20a in the figure). ), The depression 23 is formed.

Next, a method of forming the depression 23 in the second transparent substrate 11 will be described with reference to FIG. First, as shown in FIG. 4A, after forming the black matrix 12 and the color layer 13 in a predetermined region of the second transparent substrate 11, a resist is formed so as to cover the black matrix 12 and the color layer 13. UV-curable flattening film 14 such as polyimide
Is applied in a predetermined film thickness. Next, as shown in FIG. 4B, a mask 21 such as an ultraviolet ray cut filter is arranged so that the ultraviolet ray 22 does not hit the portion where the depression 23 is formed, and then the entire surface of the substrate is irradiated with the ultraviolet ray 22.

Then, the flattening film 14 is hardened in the portion where the ultraviolet rays 22 hit, and the flattening film 14 is not hardened in the portion where the mask 21 is arranged. Therefore, when the flattening film 14 is etched with a predetermined developing solution or the like, FIG. As shown in (), the flattening film 14 in the mask 21 portion is etched deeper to form a recess 23 having a predetermined shape. The shape of the depression 23 can be controlled by optimizing the irradiation conditions of the ultraviolet rays 22, the developing / etching conditions, and the like, and the depression 23 having a V-shaped cross section as shown in FIG. 2 may be formed. it can.

The effect of this depression will be described with reference to FIG. 3. In the portion where the cell gap is small, the relationship between the applied voltage of the liquid crystal and the panel transmittance is as shown by the alternate long and short dash line, but the depression 23 is formed. Since the liquid crystal is likely to rotate in the portion where the cell gap is large, the peak of the panel transmittance is shifted to the low voltage side as indicated by the chain double-dashed line. Therefore, the whole pixel is shown by the broken line, and the panel transmittance can be increased even in the low voltage region. Regarding the response, since the liquid crystal is likely to rotate in the portion where the cell gap is large, the response can be speeded up in the low voltage region, and the halftone response can be improved.

As described above, according to the structure of the liquid crystal display device of the present embodiment, by forming the depression 23 having a predetermined shape in the flattening film 14 of the second transparent substrate 11, the cell gap within one pixel is increased. A wide part and a narrow part can be formed. Therefore, since the threshold voltage Vth of the liquid crystal can be continuously changed within the pixel according to the equation 1, the response of the liquid crystal can be accelerated even in the halftone display in which the voltage applied to the liquid crystal is small.

In the present embodiment, an example in which the depression 23 has a semicircular or V-shaped cross section is described, but the present invention is not limited to the above-mentioned embodiment, and the cell gap is within the pixel. It is obvious that the depression 23 can be changed, and for example, the depression may have a U-shaped, trapezoidal, or rectangular cross-sectional shape. In addition, in this embodiment,
Since the alignment film 18 is formed on the uneven surface in which the depressions 23 are formed, the alignment film material may accumulate inside the depressions 23 when the viscosity of the alignment film material is low. Therefore, as the alignment film 18, it is preferable to form a material having a viscosity of 30 cp or more by offset printing.

[Second Embodiment] Next, an IPS type liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIGS. 5 and 6 are views showing the structure of the liquid crystal display device according to the second embodiment, wherein (a) is a plan view and (b) is a cross-sectional view taken along the line AA ′ of (a). . The difference between the first embodiment and this embodiment is that the formation direction of the depression is the data line direction,
The structure of other parts is similar to that of the first embodiment.

That is, the black matrix 12, the color layer 13, and the flattening film 1 having a predetermined thickness are formed on the second transparent substrate 11.
4 is formed, and the flattening film 14 has a semicircular cross section or V
A V-shaped recess 23 is provided, the recess 23 extends in the direction of the data line 6, and the apex region of the recess having the maximum cell gap is the pixel electrode 7 or the common electrode 3 (in the configuration of the present embodiment, the It is formed along the common electrode 3). Then, by changing the depth of the depression 23 in the pixel, the first
The cell gap between the transparent substrate 1 and the second transparent substrate 11 is changed, and the threshold voltage V
It lowers th and makes the response faster.

Therefore, a region 19b having a large cell gap is formed in a portion along the common electrode 3 at the center of the pixel, and a recess 23 is formed so that the cell gap becomes smaller as the data line 6 is approached. In the area on the data line 6 side where the cell gap is small, the relationship between the applied voltage of the liquid crystal and the panel transmittance is the same as when the electrode interval is wide, but the liquid crystal rotates because the cell gap is wide in the central portion of the depression 23. Since the peak of the panel transmittance shifts to the low voltage side, the panel transmittance of the entire pixel can be increased even in the low voltage region. Regarding the response, the liquid crystal is likely to rotate in a portion where the cell gap is wide, the response can be accelerated in the low voltage region, and the response in the halftone can be improved.

In the present embodiment, the pixel electrode 7 and the common electrode 3 may have a linear shape or a shape having a bending point, and the recess 23 may have a U-shaped, trapezoidal, or rectangular cross-sectional shape. The same as in the first embodiment described above.

[Embodiment 3] Next, an IPS type liquid crystal display device according to a third embodiment of the present invention will be described with reference to FIGS. 7 and 8 are views showing the structure of the liquid crystal display device according to the third embodiment, where (a) is a plan view and (b) is a cross-sectional view taken along the line AA ′ of (a). . The difference between the second embodiment and the present embodiment is that a plurality of recesses are formed, and the structure of other portions is the same as that of the second embodiment.

That is, a plurality of depressions 23 having a V-shaped, semicircular, U-shaped, trapezoidal or rectangular cross section are provided in the flattening film 14 on the second transparent substrate 11, and these depressions 23 are in the data line 6 direction. Are formed so as to extend in parallel with the pixel electrode 7 or the common electrode 3. Then, by changing the depth of the depression 23 in the pixel, the cell gap between the first transparent substrate 1 and the second transparent substrate 11 is changed, and the threshold voltage Vth is lowered in a portion where this cell gap is wide, and the response is increased. Can be fast.

Specifically, in this embodiment, the apex 2 of the depression is
3a is arranged between the pixel electrode 7 and the common electrodes 3 on both sides thereof so that the cell gap becomes maximum in the vicinity of the apex 23a of the depression, and the cell gap becomes narrower as approaching the inner side or the data line 6 from that region. It is set. Due to the depression 23, a region having a large cell gap can be formed, and the liquid crystal is easily rotated. Therefore, in the entire pixel, the panel transmittance can be increased in the low voltage region, and the response can be speeded up. Can be achieved.

In this embodiment, the V-shaped depression 2 has a cross section.
Although the example in which two three are provided is described, the number of the depressions 23 is arbitrary, and for example, three depressions are provided as shown in FIG. 8, and the vertices of each depression are parallel to the common electrode 3 and the pixel electrode 7. The same effect can be obtained by forming
The depth and sectional shape of the depression 23 can be changed in each depression.

[Embodiment 4] Next, an IPS type liquid crystal display device according to a fourth embodiment of the present invention will be described with reference to FIGS. 9 to 10. 9 and 10 are views showing the structure of the liquid crystal display device according to the fourth embodiment.
Is a plan view and (b) is a sectional view taken along line BB ′ of (a). Note that this embodiment is different from the above-described first to third embodiments in that a recess for changing the size of the cell gap is provided on the first transparent substrate side.

The structure of the IPS liquid crystal display device of this embodiment will be described below.
The gate electrodes 2 and the data lines 6 are formed substantially orthogonal to each other, and TFTs 4 are arranged in a matrix at the intersections thereof to form one pixel. A pixel electrode 7 and a common electrode 3 are formed in each pixel, and the common electrode 3 is the gate electrode 2
The pixel electrode 7 is formed in the same layer as the data line 6 via the interlayer insulating film 5. Then, a passivation film 10 is formed on the data lines 6 and the pixel electrodes 7. Here, in this embodiment, the inter-layer insulating film 5 and the passivation film 10 in the pixel are provided with the depressions 23 to form a wide and narrow cell gap.

Here, a method of forming the depression 23 on the first transparent substrate 1 side will be described. After forming the gate electrode 2 and the common electrode 3 on the first transparent substrate 1, the interlayer insulating film 5 is formed. The interlayer insulating film 5 in the pixel region is deposited and a resist pattern or the like having a predetermined shape is formed thereon and dry etching or wet etching is performed using this as a mask.
Are selectively removed by etching. Next, after the data line 6 and the pixel electrode 7 are formed, a passivation film 10 is deposited, and the passivation film 10 in the region where the interlayer insulating film 5 is removed is similarly removed by dry etching or wet etching to form a pixel. The depression 23 is formed. Then, the alignment film 18 is formed to form the first transparent substrate 1. In this way, the cell gap between the first transparent substrate 1 and the second transparent substrate 11 is changed by changing the depth of the depression 23 in the pixel, and the threshold voltage Vth is lowered in the portion where the cell gap is wide, The response can be quick.

That is, by forming a recess 23 extending in parallel with the gate electrode 2 through the center of the pixel region and increasing the cell gap in that region, the liquid crystal is easily rotated, and the panel transmittance has a peak low voltage. Can be shifted to the side. Therefore, in the entire pixel, the panel transmittance can be increased in the low voltage region, the response can be made faster, and the halftone display can be improved.

In this embodiment, both the interlayer insulating film 5 and the passivation film 10 are removed and the first transparent substrate 1 is removed.
The depression 23 is formed on the first transparent substrate 1, but the depression 23 is formed on the first transparent substrate 1.
10 may be formed, for example, as shown in FIG. 10, only the passivation film 10 is removed to form the depression 23, or after the passivation film 10 is deposited, the passivation film 10 and the interlayer insulating film are deposited. The film 5 is removed at the same time, or only the interlayer insulating film 5 is removed so that the step difference is reflected in the passivation film 10 to form the depression 2
3 can also be formed.

[Embodiment 5] Next, an IPS type liquid crystal display device according to a fifth embodiment of the present invention will be described with reference to FIG. 11A and 11B are views showing the structure of the liquid crystal display device according to the fifth embodiment, where FIG. 11A is a plan view and FIG.
FIG. 7A is a sectional view taken along line AA ′ in FIG. In the present embodiment, unlike the first to fourth embodiments described above,
A feature is that a black matrix and a color layer are provided on the first transparent substrate 1 side, and a recess is formed on the first transparent substrate 1 side.

Explaining the structure of the IPS liquid crystal display device of the present embodiment, first, on the first transparent substrate 1, the surplus light between the gate electrode 2, the data line 6 and these and the pixel display portion is provided. Black matrix 12 for shading,
After forming the color layer 13 for performing color display of RGB three colors, the organic interlayer film 24 having a predetermined thickness is deposited. next,
In this embodiment, the organic interlayer film 24 in the pixel region is etched under predetermined conditions to form the depression 23. Then, after the pixel electrode 7 and the common electrode 3 are formed on the organic interlayer film 24, the data line 6 is formed via the interlayer insulating film 5, and the passivation film 10 is deposited thereon. Then, the alignment film 18 is formed to form the first transparent substrate 1.

On the other hand, the alignment film 1 is formed on the second transparent substrate 11 side.
8 is formed, and the liquid crystal 17 is sandwiched between both substrates. In the liquid crystal display device having such a structure, since the black matrix 12 is formed on the side of the first transparent substrate 1 on which the electrodes are formed, the black matrix 12 and the gate electrode 2, the data line 6 and the common electrode 3 are formed. The positional relationship can be maintained more accurately. Therefore, these can be arranged with a reduced design margin, and the aperture ratio can be further increased.

As described above, in the present embodiment, the cell gap is increased by forming the depression 23 along the common electrode 3 in the center of the pixel region, and the cell gap is reduced as the data line 6 is approached. Since the liquid crystal easily rotates in a large portion, the panel transmittance can be increased in the low voltage region, the response can be made faster, and the halftone display can be improved. Further, since the black matrix 12 and each electrode are formed on the same substrate, their positional accuracy can be improved and the aperture ratio can be increased.

[Embodiment 6] Next, an IPS type liquid crystal display device according to a sixth embodiment of the present invention will be described with reference to FIG. 12A and 12B are views showing the structure of the liquid crystal display device according to the sixth embodiment, where FIG. 12A is a plan view and FIG.
FIG. 7A is a sectional view taken along line AA ′ in FIG. In this embodiment, as in the case of the above-described eighth embodiment, in the liquid crystal display device having the structure in which the black matrix and the color layer are provided on the first transparent substrate side, the depression is provided on the first transparent substrate side. However, the method of forming the pixel electrode, the shape of the recess, and the method of forming the pixel electrode are different from those of the fifth embodiment.

The structure of the IPS liquid crystal display device of the present embodiment will be described. First, the black matrix 12 for blocking excess light on the first transparent substrate 1,
A color layer 13 for performing color display of RGB three colors is formed. Next, as shown in FIG. 12B, the color layer 1 in the pixel is
The pixel electrode 7 and the common electrode 3 of 3 are removed, and the pixel electrode 7 and the common electrode 3 are formed so as to be embedded therein.

Thereafter, the organic interlayer film 24 having a predetermined thickness is deposited. At this time, the pixel electrode 7 is formed with respect to the thickness of the color layer 13.
Further, since the common electrode 3 has a small film thickness, a step is formed between the two, and the step is reflected in the organic interlayer film 24, and a depression corresponding to the step is formed on the surface of the organic interlayer film 24.
Next, the gate electrode 2 and the common electrode 3 outside the pixel are formed, the data line 6 is formed on the common electrode 3 via the interlayer insulating film 5, and then the passivation film 10 is deposited. Then, the depressions 23 corresponding to the steps are sequentially formed in the interlayer insulating film 5 and the passivation film 10. After that, the alignment film 1
8 is formed to form the first transparent substrate 1. Meanwhile, the second
Only the alignment film 18 is formed on the transparent substrate 11 side, and the liquid crystal 17 is sandwiched between both substrates.

In the liquid crystal display device having such a structure, since the black matrix 12 and the color layer 13 are formed on the side of the first transparent substrate 1 on which the electrodes are formed, the black matrix 12 and the color layer 13 are formed in the same manner as in the eighth embodiment. Since the positional relationship between the matrix 12 and the color layer 13 and the gate electrode 2, the data line 6, the pixel electrode 7 and the common electrode 3 can be maintained more accurately, these can be arranged with a reduced design margin.
The aperture ratio can be increased. Further, since the cell gap is automatically formed along the step between the pixel electrode 7 and the common electrode 3, the positional relationship between the depression 23 and the pixel electrode 7 and the common electrode 3 can be controlled more accurately.

Also in this embodiment, the cell gap increases along the pixel electrode 7 and the common electrode 3 in the pixel region,
Since the cell gap becomes smaller in other parts of the pixel, the panel transmittance can be increased and the response can be made faster even in the low voltage region, and the halftone display can be improved as in the case where the electrode interval is wide. be able to.

In this embodiment, the case where the step between the color layer 13 and the pixel electrode 7 and the common electrode 3 is reflected in the organic interlayer film 24, the interlayer insulating film 5 and the passivation film 10 has been described. Apart from this, it is obvious that a recess may be formed in the organic interlayer film 24, or a recess may be formed in the interlayer insulating film 5 and the passivation film 10.

[0061]

As described above, according to the structure of the IPS liquid crystal display device of the present invention and the method of manufacturing the same, the depressions are formed in the substrate on which the TFT is formed and the counter substrate, and the cell gap between the two substrates is widened. By providing a region where the threshold voltage of the liquid crystal is small in one pixel, the panel transmittance is large even in the portion where the voltage applied to the liquid crystal is low, the response is fast, and the halftone display characteristics are improved. Can be improved.

[Brief description of drawings]

1A and 1B are views showing a structure of a liquid crystal display device according to a first embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line BB ′ of FIG. .

2A and 2B are views showing the structure of the liquid crystal display device according to the first embodiment of the present invention, FIG. 2A is a plan view, and FIG. 2B is a sectional view taken along line BB ′ in FIG. 2A. .

FIG. 3 is a diagram showing a correlation between an applied voltage, a panel transmittance and a response of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a process cross-sectional view showing the method of manufacturing the liquid crystal display device according to the first embodiment of the present invention.

5A and 5B are views showing a structure of a liquid crystal display device according to a second embodiment of the present invention, in which FIG. 5A is a plan view and FIG. 5B is a sectional view taken along line AA ′ in FIG. .

6A and 6B are views showing a structure of a liquid crystal display device according to a second embodiment of the present invention, in which FIG. 6A is a plan view and FIG. 6B is a sectional view taken along line AA ′ in FIG. .

7A and 7B are diagrams showing a structure of a liquid crystal display device according to a third embodiment of the present invention, in which FIG. 7A is a plan view and FIG. 7B is a sectional view taken along line AA ′ in FIG. .

FIG. 8 is a sectional view showing a structure of a liquid crystal display device according to a third embodiment of the present invention.

9A and 9B are views showing a structure of a liquid crystal display device according to a fourth embodiment of the present invention, FIG. 9A is a plan view, and FIG. 9B is a sectional view taken along line BB ′ of FIG. 9A. .

10A and 10B are diagrams showing a structure of a liquid crystal display device according to a fourth embodiment of the present invention, in which FIG. 10A is a plan view and FIG.
3 is a cross-sectional view taken along line BB ′ of FIG.

11A and 11B are diagrams showing a structure of a liquid crystal display device according to a fifth embodiment of the present invention, in which FIG. 11A is a plan view and FIG.
3 is a cross-sectional view taken along the line AA ′ of FIG.

12A and 12B are views showing a structure of a liquid crystal display device according to a sixth embodiment of the present invention, in which FIG. 12A is a plan view and FIG.
3 is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 13 is a diagram showing a structure of a conventional liquid crystal display device,
(A) is a plan view and (b) is a sectional view taken along the line AA 'of (a).

FIG. 14 is a diagram showing a correlation between a voltage applied to a conventional liquid crystal display device, a panel transmittance, and a response.

FIG. 15 is a diagram showing an electric field direction of a conventional liquid crystal display device.

FIG. 16 is a diagram showing an electric field direction of a conventional liquid crystal display device.

[Explanation of symbols]

1 First transparent substrate 2 Gate electrode 3 common electrode 4 TFT 5 Interlayer insulation film 6 data lines 7 pixel electrode 8 Source electrode 9 Drain electrode 10 Passivation film 11 Second transparent substrate 12 Black matrix 13 color layers 14 Flattening film 15 Conductive film 16a, 16b Polarizing film 17 LCD 18 Alignment film 19a, 19b Region with large cell gap 20a, 20b Region with small cell gap 21 mask 22 UV 23 hollow 23a The top of the depression 24 Organic interlayer film

Continued front page    F-term (reference) 2H090 HA01 HA02 HD03 JA02 KA03                       LA01 MA02 MA07                 2H092 GA14 GA17 NA05 NA07 NA26                       QA05

Claims (11)

[Claims] 1. A plurality of gate lines and a plurality of data lines, which have a pair of opposing substrates and a liquid crystal sandwiched between the pair of substrates, and are substantially orthogonal to each other on at least a first substrate. A pixel electrode and a common electrode that are alternately formed in each pixel surrounded by the gate line and the data line, and an insulating film that covers each electrode. A black matrix having openings, a color layer, and a flattening film covering the black matrix and the color layer. The voltage applied between the pixel electrode and the common electrode extends the data line. In an IPS type liquid crystal display device for controlling a liquid crystal oriented in a direction in a plane substantially parallel to the substrate, a recess having a predetermined cross-sectional shape is formed in at least one of the insulating film and the flattening film, Opposed by the depression The liquid crystal display device, characterized in that different regions of the gap between the plates is formed in the pixel region. 2. The recess is formed so as to extend in a direction parallel to the gate line, passing through the center of the pixel, and regions having different gaps are formed line-symmetrically with respect to a line connecting the vertices of the recess as an axis. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided. 3. The liquid crystal display according to claim 1, wherein the recess is formed so that a line connecting the vertices of the recess extends along the longitudinal direction of the pixel electrode or the common electrode. apparatus. 4. A pair of opposing substrates and a liquid crystal sandwiched between the pair of substrates, wherein one of the pair of substrates comprises:
A black matrix having a predetermined opening, a color layer, a plurality of gate lines and a plurality of data lines substantially orthogonal to each other,
A pixel electrode and a common electrode alternately formed in each pixel surrounded by the gate line and the data line; an interlayer film covering the black matrix and the color layer; and an insulating film covering each electrode. An IPS liquid crystal display that has at least the liquid crystal oriented in the extending direction of the data line in a plane substantially parallel to the substrate by a voltage applied between the pixel electrode and the common electrode. In the device, a liquid crystal is characterized in that a recess having a predetermined cross-sectional shape is formed in the interlayer film or the insulating film, and regions having different gaps between the opposed substrates are formed in the pixel region by the recess. Display device. 5. The color layer is divided and formed in the pixel, and the pixel electrode and the common electrode are formed in the same layer as the color layer so as to fill a space between the divided color layers. The liquid crystal display device according to claim 4, wherein the recess is formed in the interlayer film or the insulating film due to a difference in film thickness between the pixel electrode and the common electrode and the color layer. 6. The depression is formed so that a line connecting the vertices of the depression extends along the longitudinal direction of the pixel electrode or the common electrode.
The liquid crystal display device according to item 1. 7. The liquid crystal display device according to claim 1, wherein a plurality of the recesses are arranged in parallel with each other. 8. The cross section in the direction orthogonal to the extending direction of the depression is any one of a semicircle, a U-shape, a V-shape, a trapezoid or a rectangle. The liquid crystal display device according to 1. 9. The alignment film formed on the liquid crystal holding surface side of the pair of substrates is a film formed by offset printing using a material having a viscosity of 30 cp or more. 8. The liquid crystal display device according to any one of 8. 10. The method for manufacturing the liquid crystal display device according to claim 1, wherein an ultraviolet curable material is used as the flattening film or the interlayer film, and the flattening film or A method for manufacturing a liquid crystal display device, characterized in that after forming the interlayer film, ultraviolet rays are locally irradiated to form depressions having a predetermined cross-sectional shape. 11. The method of manufacturing a liquid crystal display device according to claim 10, wherein an ultraviolet curable resin made of resist or polyimide is used as the ultraviolet curable material, and ultraviolet rays are locally irradiated by an ultraviolet cut filter.