JPH10253967A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of achieving a satisfactory display without display unevenness by obtaining uniform gaps between substrates without reducing the aperture ratios of pixels while installing columnar spacers. SOLUTION: In this liquid crystal display device, protrusions 6 having heights equivalent to heights of the difference of level are provided at difference of level parts being over scanning lines 1 which are not covered with a protective film 5 or positions extremely close to TFTs being over the scanning lines 1 on a TFT array substrate and columnar spacers 7 formed on a counter substrate by laminating coloring layers of respective colors are installed in areas where the difference of level is dissolved and flattened by the protrusions 6. Moreover, the protrusion 6 is formed, for example, with at least one layer of layers constituting the TFT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, large-sized, high-definition, active matrix type liquid crystal display devices have been developed in the field of information equipment mainly for computers and video equipment mainly for televisions.

In recent years, in an active matrix type liquid crystal display device, a columnar spacer is used instead of a plastic bead as a spacer (spacer) for keeping a constant gap between an array substrate and a counter substrate. In other words, in order to eliminate the reduction in contrast due to light leakage around the plastic beads and the uneven display due to uneven scattering, a columnar spacer is formed by stacking a plurality of colored layers on the counter substrate side, and the spacer is formed. Thus, the gap between the substrates is kept constant.

[0004]

In a liquid crystal display device using such a columnar spacer, it is preferable to dispose the spacer on the scanning line in order to improve the aperture ratio of the pixel. However, there is a problem that the distance between the substrates (cell gap) cannot be controlled uniformly due to the step existing on the main surface (opposing surface) of the array substrate.

For example, in a TFT (thin film transistor) array substrate, a portion not covered with an insulating protective film exists on a scanning line to improve the yield. However, when a columnar spacer is provided in such a portion. In (2), unevenness was apt to occur in the cell gap due to the step caused by the presence or absence of the protective film, and good display was not obtained.

The present invention has been made to solve these problems. By providing a columnar spacer made of a colored layer, a uniform gap can be obtained between the substrates without reducing the aperture ratio of pixels, and display unevenness can be obtained. It is an object of the present invention to provide a liquid crystal display device capable of achieving good image quality without any display.

[0007]

According to the liquid crystal display device of the present invention, a plurality of scanning lines and a plurality of signal lines are formed on an insulating substrate so as to intersect with each other, and a switching element is provided at each intersection. A first substrate, a second substrate on which an opposing electrode is formed on an insulating substrate, and the first substrate and the second substrate.
And a liquid crystal layer sandwiched between the first substrate and the second substrate, wherein the columnar spacer of the first substrate is provided. In a liquid crystal display device having a step in a region to be
At least one protrusion having a height that reduces the step is formed at the lower part of the step, and the end surface of the columnar spacer is brought into contact with the upper surface of the protrusion and the upper surface of the high part of the step. Features.

In the present invention, a columnar spacer for keeping a gap between two substrates is usually formed on a second substrate (a counter substrate) by laminating a plurality of layers of different colors (colored layers). It is formed so as to protrude, and a counter electrode is formed thereon. By changing the thickness (height) and the stacking order of each colored layer, the height of the entire columnar spacer can be freely changed, and by making the stacking order constant, a stable height can be obtained. Columnar spacers can be formed.

In the present invention, it is desirable that the projections provided on the low-step portion of the first substrate (array substrate) be formed simultaneously with the formation of the same layer by using the same layer material. In particular, T
When an FT is provided and a projection is provided on, for example, a scanning line near the TFT, it is preferable that the projection be formed by at least one of a plurality of layers constituting the TFT.

[0010] Further, such a projection has a height necessary and sufficient to eliminate the height difference of the step and to flatten the region where the columnar spacer is provided. It is desirable to provide in the upper non-opening.

[0011] In the liquid crystal display device of the present invention, on the first substrate (array substrate) side, a protrusion having a height corresponding to the height of the step is formed on the step in the non-opening area where the columnar spacer is provided. Since the columnar spacers are formed so as to be in contact with the upper surfaces of the protrusions and the upper portions of the steps, uneven cell gaps are eliminated. Therefore, display unevenness due to cell gap unevenness is eliminated, and the yield is improved. In addition, since the step portion is flattened by the formation of such projections, the installation area of the columnar spacer can be secured without lowering the aperture ratio, and the columnar spacer can be installed at an optimum position.

[0012]

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

FIG. 1 is a plan view showing a liquid crystal cell obtained by combining a TFT array substrate and a counter substrate in an embodiment of the liquid crystal display device of the present invention as seen through from the counter substrate side. FIG. 2 is a sectional view of the columnar spacer installation portion in FIG.
FIG. 3 is a cross-sectional view taken along line A of FIG.
FIG. 4 shows a cross-sectional view of the FT section along line BB.

First, T used in the liquid crystal display device of the embodiment will be described.
The outline of the FT array substrate will be described. In this TFT array substrate, as shown in FIG. 1, a plurality of scanning lines 1 and signal lines 2 are formed on an insulating substrate so as to intersect with each other. Is formed. In each pixel, a gate electrode and a drain electrode of the TFT 3 are integrally formed so as to protrude from the scanning line 1 and the signal line 2, respectively, and a source electrode is connected to the pixel electrode 4. Further, except for a predetermined portion 1a on the scanning line 1, the scanning line 1, the signal line 2, and the TF
An insulating protective film 5 is continuously formed on T3, and a step is formed in a part 1a on the scanning line 1 not covered by such a protective film 5. Further, a projection 6 having a height corresponding to the height of the step is provided in a portion having a low step, and a columnar spacer 7 is provided in a region on the scanning line 1 including the projection 6.

The structure of such a TFT array substrate will be described in more detail.

In the TFT array substrate of the liquid crystal display device according to the embodiment, as shown in FIGS. 2 and 3, Al, Mo, W, and T are formed on a transparent insulating substrate 8 such as a glass substrate.
A scanning line 1 made of a metal such as a or Ti and a gate electrode 9 are integrally formed, and a gate insulating film 10 made of silicon oxide or the like is formed thereon. The pixel electrode 4 made of a transparent material such as indium tin oxide (ITO) is formed on the gate insulating film 10. Also, the gate insulating film 1 above the gate electrode 9
A semiconductor layer 11 such as a-Si (amorphous silicon), a low-resistance semiconductor layer (contact layer) 12, and an etching protection film 13 made of silicon nitride or the like are provided in this order on the semiconductor substrate 11. A drain electrode 14 and an island-shaped source electrode 15 connected to the layer 12 are respectively formed in the same layer as the signal line 2, and a channel protection type TF
T3 is formed. On a predetermined portion 1a on the scanning line 1, a semiconductor layer 11 constituting the TFT 3 and an etching protection film 13 are laminated in an island shape, and have a small size (for example,
μm × 15 μm) are formed. Except for the area around the projection 6, an insulating protective film 5 is formed on the scanning line 1, the signal line 2, and the TFT 3 so as to cover it. (Not shown) is applied, and an alignment process by rubbing is performed.

On the other hand, on the counter substrate side, a light shielding layer (black matrix) 16 is formed on a transparent insulating substrate 8 such as a glass substrate, and R (red), G (green),
A color filter (not shown) is formed by forming each colored layer of B (blue) in a predetermined pattern. In forming a color filter, the red coloring layer 17R, the green coloring layer 17G, and the blue coloring layer 17B are formed.
Are sequentially laminated at predetermined positions on the light shielding layer 16, thereby forming a columnar spacer 7 of, for example, 15 μm × 30 μm.

Here, the formation of the light shielding layer 16 and the color filters, and the formation of the columnar spacers 7 are performed, for example, by the following method. First, a photosensitive black resin is applied on the insulating substrate 8, and a light-shielding layer 16 is formed by sequentially performing exposure, development, and baking, and then an ultraviolet-curable acrylic resin resist in which a red pigment is dispersed is applied. Then, exposure, development, and baking are sequentially performed to form a red colored layer. At this time, a red coloring layer 17R is formed at a predetermined position on the light-shielding layer 16 by the same method, and a red spacer portion is formed.
Next, a green colored layer is formed in the same manner using an ultraviolet-curable acrylic resin resist in which a green pigment is dispersed, and at the same time, a green colored layer 17G is also laminated on the previously formed red spacer portion. Forming a red-green laminated spacer portion, and further forming a blue colored layer with an ultraviolet curable acrylic resin resist in which a blue pigment is dispersed, and simultaneously forming a blue-colored layer on the previously formed red-green laminated spacer portion. Also, a blue colored layer 17B is laminated, and red-green-
A columnar spacer 7 in which three colored layers of blue are sequentially stacked is formed.

Further, a counter electrode (not shown) made of ITO is formed on the color filter thus formed, and an alignment film (not shown) made of polyimide is further applied thereon. Alignment treatment by rubbing is performed. The opposing substrate and the above-described TFT array substrate have the surface on which the alignment film is formed on the inside, and the columnar spacer 7 protrudingly formed on the opposing substrate side is formed with the protrusion 6 on the TFT array substrate side. The liquid crystal composition 1 such as a TN liquid crystal is disposed between the substrates so as to face each other so as to be set in a step region on the scanning line 1.
8 are pinched.

In the liquid crystal display device of the embodiment constructed as described above, the projection 6 is formed at the lower part of the step on the scanning line 1 of the TFT array substrate, and the columnar spacer is formed in the area flattened by the projection 6. Since 7 is provided, a uniform gap between the substrates can be obtained. Therefore, display unevenness is eliminated, and display with good image quality can be achieved. Further, the area where the columnar spacer 7 can be installed without lowering the aperture ratio is expanded.

Next, another embodiment of the liquid crystal display device of the present invention will be described with reference to FIGS. Note that, in these figures, the same parts as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted.

In the liquid crystal display device of this embodiment, the scanning line 1 very close to the TFT 3 is formed on the TFT array substrate.
At the upper position, a semiconductor layer 11 made of a-Si, an etching protection film 13, and a metal layer 19, which is the same as the signal line 2, are sequentially stacked in an island shape, and a projection 6 having a size of, for example, 15 μm × 20 μm is formed. And an insulating protective film 5 thereon.
Is coated.

On the other hand, on the counter substrate side, a red coloring layer 17R, a green coloring layer 17G, and a blue coloring layer 17B are formed on the light shielding layer 16 formed on the insulating substrate 8 in the same manner as in the above embodiment.
Are sequentially laminated, for example, 20 μm × 40
A columnar spacer 7 having a size of μm is formed. Then, the columnar spacer 7 formed on the counter substrate side such that the counter substrate and the above-described TFT array substrate are connected to each other by the TFT
The TFTs 3 and the projections 6 formed on the scanning lines 1 on the array substrate side are disposed so as to face each other so as to be installed in a stepped area. That is, the opposing substrate and the TFT array substrate are disposed so as to face each other such that the tip end surface of the columnar spacer 7 is in contact with the upper surface of the TFT 3 and the upper surface of the protrusion 6 via the protective film 5. A liquid crystal composition 18 such as a liquid crystal is sandwiched.

In the liquid crystal display device of this embodiment, since the step in the region including the TFT 3 where the columnar spacer 7 is provided is flattened by the projection 6, a uniform gap can be obtained between the substrates. Thus, it is possible to obtain a good display without display unevenness. Also, as compared with the above-described embodiment, the TFT 3 and the step region on the scanning line 1 adjacent thereto have a larger size (cross-sectional area) without lowering the aperture ratio.
Since the columnar spacer 7 can be provided, the strength of the panel can be further improved. In the second embodiment, the projection 6 is formed on the scanning line 1 adjacent to the TFT 3, but the projection 6 is formed on the signal line 2 adjacent to the TFT 3, and the step including the projection 6 and the TFT 3 is formed. The same effect can be obtained by providing the columnar spacer 7 in the region.

[0025]

As is apparent from the above description, in the liquid crystal display device of the present invention, a projection corresponding to the height of the step is formed at the step in the non-opening area where the columnar spacer of the array substrate is installed. Since it is provided, the step is eliminated and the surface is flattened, a uniform cell gap can be obtained without lowering the aperture ratio. Therefore, display unevenness due to cell gap unevenness is eliminated, and high-brightness and good display can be obtained.

Further, the flat area where the columnar spacer can be placed is expanded, and the degree of freedom of design is expanded. Therefore, a high-performance, low-cost liquid crystal display device can be obtained by optimal design.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal display device according to an embodiment of the present invention, in which a liquid crystal cell is seen through from a counter substrate side.

FIG. 2 is a cross-sectional view of the columnar spacer installation section in FIG. 1 taken along line AA.

FIG. 3 is a cross-sectional view of the TFT section in FIG. 1 along the line BB.

FIG. 4 shows another embodiment of the liquid crystal display device of the present invention.
FIG. 3 is a plan view of the liquid crystal cell seen through from a counter substrate side.

FIG. 5 is a cross-sectional view of the columnar spacer installation section in FIG. 4 taken along line AA.

FIG. 6 is a cross-sectional view of the TFT section in FIG. 4 along the line BB.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Scanning line 2 ... Signal line 3 ... TF4 4 ... Pixel electrode 5 ... Insulating protective film 6 ... Protrusion 7 ... Column spacer 8 ... Insulating substrate 9 ... ... Gate electrode 10 Gate insulating film 11 Semiconductor layer 12 Low-resistance semiconductor layer 13 Etching protective film layer 14 Drain electrode 15 Source electrode 16 … Light-shielding layer 17R… red coloring layer 17G… green coloring layer 17B… blue coloring layer 18… liquid crystal composition 19… metal layer

Claims (3)

[Claims] 1. A first substrate having a plurality of scanning lines and a plurality of signal lines formed on an insulating substrate so as to intersect with each other, and a switching element provided at each of the intersections; A second substrate on which a counter electrode is formed, a columnar spacer provided to maintain a gap between the first substrate and the second substrate, and a second spacer between the first substrate and the second substrate. A liquid crystal display device having a sandwiched liquid crystal layer, and a step in a region of the first substrate where the columnar spacer is provided, wherein at least a low portion of the step has a height to reduce the step. A liquid crystal display device, wherein one projection is formed, and an end surface of the columnar spacer is in contact with an upper surface of the projection and an upper surface of a high portion of the step. 2. The method according to claim 1, wherein the first spacer on which the columnar spacer is installed is provided.
2. The liquid crystal display device according to claim 1, wherein a region of the substrate is a region including the switching element, and the projection is formed on the scanning line adjacent to the switching element. 3. The liquid crystal display device according to claim 2, wherein said switching element is a thin film transistor, and said projection is formed by at least one layer constituting said thin film transistor.