JPH10246882A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the space between two substrates constant and to prevent production of concentric interference fringes by forming a recess part which constitutes the space to seal a liquid crystal on at least one of the surfaces of the first and second substrates facing each other. SOLUTION: A recess part 100 to constitute a space to seal a liquid crystal 209 is formed on the counter surface of a second substrate 120, and a color filter 204 and a common electrode 214 are formed in the recess part 100. Thereby, by laminating the two substrates with an adhesive 115, a container to seal a liquid crystal is obtd. In this case, a mask is formed on a glass substrate to form openings in the processed part and the substrate is etched to form the recess part 100. This etching may be carried out by wet etching using a photoresist as a mask and a hydrofluoric acid soln., or by dry etching using a metal such as aluminum as a mask and sulfur hexafluoride gas.

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 having minute pixels, and more particularly, to a liquid crystal display device having a driving circuit on a TFT (Thin Film Transisitor), that is, a thin film transistor (TFT) type substrate comprising polysilicon transistors. The present invention relates to a technology effective when applied to a projection type liquid crystal display device.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device, pixels formed by intersection regions of stripe-shaped XY electrodes provided on respective opposing surfaces of upper and lower substrates so as to intersect with each other when viewed from the vertical direction. , And an active matrix type liquid crystal display device having an active element for each pixel and performing a switching operation of the active element.

An active matrix type liquid crystal display device is characterized in that a liquid crystal driving voltage (gradation voltage) is applied to a pixel electrode through an active element such as a thin film transistor, so that there is no crosstalk between pixels, and a simple matrix type liquid crystal display device. Unlike a liquid crystal display device, there is no need to use a special driving method for preventing crosstalk, and multi-gradation display is possible.

One of the active matrix type liquid crystal display devices is a TFT type active matrix type liquid crystal display device using an amorphous silicon transistor or a poly silicon transistor (polycrystalline silicon transistor) as a thin film transistor. It has been known.

Hereinafter, in this specification, an amorphous silicon transistor is referred to as an a-SiTr,
P-SiTr as a silicon transistor, a-SiTFT liquid crystal display using a TFT type liquid crystal display using amorphous silicon transistors, and p-SiTFT liquid crystal display using a TFT type liquid crystal display using poly-silicon transistors. It is called a device.

[0006] The a-Si TFT liquid crystal display device is widely used as a display device of a personal computer or a television.

However, in an a-Si TFT liquid crystal display device, a driving circuit for driving liquid crystal is provided on a liquid crystal display panel (ie, a liquid crystal display element, an LCD (Liquid Crysta)).
l Display)).

On the other hand, in recent years, a TFT liquid crystal display device using p-SiTr has been developed and commercialized.

A liquid crystal display panel of a p-SiTFT liquid crystal display device (hereinafter referred to as a p-SiTFT liquid crystal display panel) is similar to a liquid crystal display panel of an a-SiTFT liquid crystal display device (hereinafter referred to as an a-SiTFT liquid crystal display panel). A p-SiTr is arranged and formed in a matrix on a quartz or glass substrate.

Furthermore, the operating speed of the p-SiTr is aS
Since it is faster than iTr, in a p-SiTFT liquid crystal display panel, its peripheral circuits can be formed on the same substrate.

FIG. 8 is a schematic sectional view of a main part of a conventional p-Si TFT liquid crystal display panel. 8, 210 is a first glass substrate, 220 is a second glass substrate, 203
Is a light shielding film, 204 is a color filter, 205 is a protective film,
214 is a common electrode, 206 is an alignment film, 207 is a sealing material, 209 is liquid crystal, 208 is a spacer, 116 is a pixel electrode (pixel region), and 211 is a polarizing film.

As shown in FIG. 8, a first glass substrate 21
A large number of fine spherical (or cylindrical) spacers 208 made of glass, alumina, silica, polymer, or the like are provided between the first glass substrate 220 and the second glass substrate 220 in order to secure a gap for holding the liquid crystal 209 therebetween. It is provided in a liquid crystal 209.

In a conventional method of assembling a liquid crystal display panel, a sealing material 207 made of a thermosetting epoxy resin material or the like is formed in a frame shape (a square shape) around a second glass substrate 220. Spacers 208 such as beads and fibers are dispersed on the opposing surface of the glass substrate 220, and the first glass substrate 210 and the second glass substrate 220 are combined, and the outer surfaces of both substrates are pressed. Heat and seal material 2
07 is cured, and the two substrates are bonded at regular intervals.

FIG. 9 shows the conventional p-SiTF shown in FIG.
FIG. 3 is a schematic plan view of a first glass substrate 210 of the T liquid crystal display panel.

In FIG. 9, a display area (display section) 221 is shown.
On the liquid crystal side surface of the first glass substrate 210 (the surface facing the second substrate 220 in FIG. 8), for example, the first glass substrate 210 extends in the horizontal direction with respect to the first glass substrate 210 and in the vertical direction. Are formed in parallel with each other, and a drain signal line 223 which is insulated by these gate signal lines 222 and extends in the vertical direction and is arranged in the horizontal direction. A pixel region is formed near the intersection of each of these signal lines. The plurality of pixel regions are arranged in a matrix and form a display region 221. In FIG. 9, only one pixel region (upper left) is shown by an equivalent circuit for simplification,
Others are not shown. 224 is a thin film transistor, 2
25 is a liquid crystal capacity, and 226 is a storage capacity. The thin film transistor 224 is turned on / off by a scanning signal from the gate signal line 222, and a video signal from the drain signal line 223 is transmitted to the pixel electrode 116 through the thin film transistor 224.
Is written and held as a liquid crystal drive voltage (grayscale voltage). The pixel electrode 116 forms one electrode of the liquid crystal capacitor 225, and the common electrode 214 forms the other electrode (FIG. 8).
reference). Reference numeral 227 denotes a connection terminal group for connecting to an external circuit. The vertical scanning circuit 228 and the horizontal scanning circuit 229 are driving circuits for supplying various signals for driving the thin film transistor 224.

[0016]

In a conventional liquid crystal display device, as shown in FIG.
The seal member 207 provided between the substrates 20 is heated while being pressed from the outside, and is bonded by curing and assembling. In order to keep the distance between the two substrates constant, a large number of spacers 208 and the like are provided in the display area 221 (FIG. 9). Was provided in a dispersed manner. However,
It is not easy to keep the distance between the two substrates constant, and there has been a problem such as display failure due to uneven distance. Further, in the projection type liquid crystal display device, since the shadow of the spacer is projected at the time of enlarged projection, the spacer or the like cannot be used, and it is more difficult to keep the distance between the two substrates constant.

Further, even if beads or fibers are put in the sealing material to keep the distance between the two glass substrates constant, the distance is maintained only around the display section, and the center of the display section is bent. On the screen, this deflection was seen as concentric interference fringes (referred to as Newton rings) due to the interference of light, and the image quality was degraded.

Further, the distance between the two glass substrates is maintained by pressing an elastic spacer such as a bead or a fiber, and the adjustment of the conditions such as the pressing condition and the width of the sealing material is delicate. It was difficult to form a predetermined distance between the glass substrates.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a liquid crystal display device having a structure in which a distance between two substrates can be kept constant.

It is another object of the present invention to provide a liquid crystal display device having a structure in which a shadow of a spacer is not projected during enlarged projection.

[0021]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application. That is, (1) a first substrate, a second substrate, and a liquid crystal sandwiched between the first substrate and the second substrate, wherein the first substrate and the second substrate A liquid crystal display device is provided in which at least one of the opposing surfaces of the substrate is provided with a concave portion forming a gap for enclosing the liquid crystal.

(2) It has a first substrate, a second substrate, and a liquid crystal sandwiched between the first substrate and the second substrate, and the first substrate and the second substrate A liquid crystal display device is provided in which at least one of the opposing surfaces of the two substrates is provided with a recess forming a gap for enclosing the liquid crystal.

(3) It has a first substrate, a second substrate, and a liquid crystal sandwiched between the first substrate and the second substrate, and the first substrate and the second substrate A gap forming layer (that is, a spacer film) is provided between the two substrates, and the gap forming layer is processed to provide a gap for enclosing the liquid crystal.

In the liquid crystal display device configured as described above,
A spacer forming a gap for enclosing liquid crystal between the first substrate and the second substrate can be provided integrally with the substrate on at least one of the first substrate and the second substrate. Can be kept constant.

[0025]

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

In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

[First Embodiment] FIG. 1 is a schematic sectional view of a main part of a liquid crystal display panel according to a first embodiment of the present invention.

In FIG. 1, reference numeral 110 denotes a first substrate;
0 is the second substrate, 100 is the concave portion of the second substrate 120, 1
16 is a pixel electrode, 115 is an adhesive, 214 is a common electrode,
203 is a light shielding film, 204 is a color filter, 206 is an alignment film, and 209 is a liquid crystal.

The liquid crystal 20 is provided on the opposing surface of the second substrate 120.
A concave portion (concave) 100 forming a gap for enclosing 9
The color filter 204 and the common electrode 214 are formed in the recess 100. In addition, illustration of a polarizing plate etc. is omitted for simplification.

In the first embodiment, as compared with the conventional method in which the sealing material is cured to surround the periphery of the display portion and form a container in which the liquid crystal is sealed with the two substrates and the sealing material.
It is possible to form a container for enclosing a liquid crystal by bonding two substrates with an adhesive 115.

FIGS. 2A and 2B are process cross-sectional views showing a method for forming a concave portion in a glass substrate by etching. As shown in FIG. 2A, a mask 311 is formed on a glass substrate 310 so as to open an opening in a processed portion.
As shown in (b), etching is performed to form the recess 100. Etching is performed by using a photoresist or the like as the mask 311 and wet etching using a hydrofluoric acid-based solution or the like, or using dry etching using a metal such as aluminum and a sulfur hexafluoride gas as the mask 311. You may. Further, the concave portion 100 may be formed by using a sand blast method.

[Second Embodiment] FIG. 3 is a schematic sectional view of a main part of a liquid crystal display panel according to a second embodiment of the present invention.

In the second embodiment, the concave portion 100 forming a gap for enclosing the liquid crystal 209 is formed on both the opposing surfaces of the second substrate 120 and the first substrate 110. When the concave portion 100 is formed in this manner, the depth of the concave portion 100 provided on one substrate can be reduced to half, and when the alignment film 206 is rubbed, a step between the peripheral portion and the display portion (for example, 4 ６6 μm) is divided into two substrates (2 to 3 μm), and the problem that rubbing due to a step cannot be sufficiently performed can be solved.

Third Embodiment FIG. 4 is a schematic sectional view of a main part of a liquid crystal display panel according to a third embodiment of the present invention.

In the third embodiment, a concave portion 100 forming a gap for enclosing the liquid crystal 209 is formed on the opposing surface of the second substrate 120, and a drive circuit (see FIG. 9) is provided separately from the concave portion 100. 4, only the vertical scanning circuit 228 is shown. The same applies to the horizontal scanning circuit 229 in FIG. 9). By providing the driving circuit so as not to be in contact with the liquid crystal 209 by using the concave portion 400 provided in the substrate 120 in this manner, problems such as electrolysis of the liquid crystal caused by the potential of the driving circuit can be prevented.

[Embodiment 4] FIG. 5A is a schematic sectional view showing a main part of a liquid crystal display panel according to Embodiment 4 of the present invention.
FIG. 5B is a schematic plan view of a main part of the second substrate 120 of FIG.

In the fourth embodiment, the concave portion 100 forming a gap for enclosing the liquid crystal 209 on the opposing surface of the second substrate 120 is processed along the drain signal line 223 shown in FIG. Color filter 20 for every 100
4. The common electrode 117 and the alignment film 206 are formed. With such a structure in which the wall of the substrate 120 exists between the drain signal lines, it is possible to make the substrates 110 and 120 more resistant to bending. In addition, if the same color filter 204 is formed for each recess 100, there is no need to provide a boundary for each color, and a light-shielding film (reference numeral 203 in FIGS. 1, 3, and 4)
Can be deleted.

As described above, the recess 100 is provided for each drain signal line.
Is provided, the gap for enclosing the liquid crystal 209 can be kept constant, the gap can be made smaller, and the problem of rubbing failure due to a step can be solved. In the fourth embodiment, the recess 100 is formed for each drain signal line. However, although not shown, the recess 100 is formed for each gate signal line (see reference numeral 222 in FIG. 9) or for each pixel. It may be formed. If the concave portion 100 is formed for each pixel, the structure becomes stronger against the deflection of the substrate.

Further, as shown in FIG.
Reference numeral 0 is connected to the other recess 100 at one end by an inflow path 114, and has a shape such that the liquid crystal 209 flowing from the sealing port 113 of the liquid crystal 209 can flow into each recess 100.

[Embodiment 5] FIG. 6 is a schematic sectional view of a main part of a liquid crystal display panel according to Embodiment 5 of the present invention.
(A)-(c) is sectional drawing of the manufacturing process of the 2nd board | substrate of FIG.

In the fifth embodiment, a spacer film (gap forming layer) 108 for previously forming a gap for enclosing liquid crystal is formed on the facing surface of the second substrate 120, and thereafter, the spacer film 108 is illustrated. By processing like
A gap for enclosing the liquid crystal 209 is formed.

Next, a method of manufacturing the second substrate 120 used in the liquid crystal display panel of the fifth embodiment shown in FIG. 6 will be described step by step with reference to FIGS. .

Step 1. (FIG. 7A) On the surface of the second substrate 120, a light shielding film 203, a color filter 204, a common electrode 214, an alignment film 206, and a processing protection film 109 are formed.

Step 2. (FIG. 7B) Next, a spacer film 108 made of glass paste or the like and a resist layer 10
7 is formed, and a pattern for processing the spacer film 108 is formed on the resist layer 107 by photolithography.

Step 3. (FIG. 7C) Next, using the patterned resist layer 107 as a mask,
The spacer film 108 is processed as shown by using a sand blast method or the like. After that, the resist layer 107 and the processing protection film 109 (for protecting the alignment film 206) at the processing bottom of the spacer film 108 are removed.

Thereafter, the second substrate 120 and the first substrate 110 on which the pixel electrodes 116 and the alignment film 206 shown in FIG. 6 are formed are bonded with an adhesive 115 to form a liquid crystal display panel. .

The effects of the above embodiment are described as follows.

(1) Even in a large-area liquid crystal display panel, the distance between the two substrates can be kept constant without providing a conventional dispersing spacer or the like in the pixel region. Therefore, the present invention is particularly effective when applied to a projection-type liquid crystal display device in which a display screen is enlarged.

(2) It is possible to prevent concentric interference fringes from occurring on the screen without bending the center of the display section.

(3) As compared with a conventional liquid crystal display panel in which the outer surfaces of both substrates are pressed through an elastic spacer such as a bead or a fiber to maintain the distance between the substrates, the pressing conditions, the width of the sealing material, There is no need to finely adjust the condition elements such as the method of applying the sealing material, and the gap can be controlled by using FIGS.
In the fourth and fifth embodiments, depending on the etching time of the glass substrate, and in the embodiment of FIG.
The distance between the two substrates can be controlled to a predetermined value. As a result, the manufacturing cost can be suppressed and the quality can be improved.

As described above, the present invention has been specifically described based on the embodiments. However, it is needless to say that the present invention is not limited to the above-described embodiments and can be variously modified without departing from the gist thereof. No. For example, in FIGS. 1, 3, 4, and 5, in order to form the concave portion 100 in the substrate 120 or 110, depending on the material of the substrate, the concave portion 100 may be integrally formed at the time of manufacturing, instead of being processed by etching or sandblasting. Needless to say, this may be done. Also,
In FIG. 5, in addition to the liquid crystal charging port 113, a port through which air in the gap for liquid crystal charging is drawn using a vacuum pump is provided on the substrate 120.
And a configuration in which the liquid crystal 209 can be easily injected. 1, 3, 4, and 5, the surface of the substrate 120 on the side opposite to the side where the concave portion 100 is provided is processed into a lens shape for each pixel region, and the irradiated light is collected in the pixel portion. May be adopted. Further, the present invention can be applied to a simple matrix type liquid crystal display device, a vertical electric field type or horizontal electric field type active matrix type liquid crystal display device, or a COG (chip-on-glass) type liquid crystal display device. Needless to say.

[0052]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) The distance between the two substrates can be kept constant without providing a spacer or the like in the pixel region.

(2) Concentric interference fringes generated on the screen can be prevented without bending the center of the display section.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a liquid crystal display panel according to Embodiment 1 of the present invention.

FIGS. 2A and 2B are process cross-sectional views illustrating a method of forming a concave portion in a glass substrate by etching.

FIG. 3 is a schematic sectional view of a main part of a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a main part of a liquid crystal display panel according to a third embodiment of the present invention.

5A is a schematic cross-sectional view of a main part of a liquid crystal display panel according to a fourth embodiment of the present invention, and FIG. 5B is a schematic plan view of a main part of a second substrate 120 of FIG. .

FIG. 6 is a schematic cross-sectional view of a main part of a liquid crystal display panel according to Embodiment 5 of the present invention.

7 (a) to 7 (c) are cross-sectional views illustrating manufacturing steps of a second substrate of the liquid crystal display panel of FIG.

FIG. 8 is a schematic sectional view of a main part of a conventional p-Si TFT liquid crystal display panel.

9 is a schematic plan view of a first glass substrate 210 of the conventional p-Si TFT liquid crystal display panel shown in FIG.

[Explanation of symbols]

Reference numeral 100: concave portion, 107: resist layer, 108: spacer film, 109: protective film for processing, 110: first substrate, 11
5 adhesive, 116 pixel electrode, 120 second substrate,
203: light shielding film, 204: color filter, 205: protective film, 206: alignment film, 207: sealing material, 208: spacer, 209: liquid crystal, 210: first glass substrate, 2
11: polarizing plate, 214: common electrode, 220: second glass substrate, 221: display area, 222: gate signal line, 2
23: drain signal line, 224: thin film transistor, 2
25: liquid crystal capacitor, 226: holding capacitor, 227: connection terminal group, 228: vertical scanning circuit, 229: horizontal scanning circuit, 3
10: glass substrate, 311: mask, 400: recess.

Claims (6)

[Claims] A first substrate, a second substrate, and a liquid crystal interposed between the first substrate and the second substrate, wherein the first substrate and the second substrate are connected to each other. A liquid crystal display device provided with a concave portion forming a gap for enclosing the liquid crystal in at least one of the opposing surfaces of the substrate. 2. A semiconductor device comprising: a first substrate; a second substrate; and a liquid crystal sandwiched between the first substrate and the second substrate. A liquid crystal display device, wherein at least one of the opposing surfaces of the substrate is provided with a concave portion forming a gap for enclosing the liquid crystal. 3. The liquid crystal display device according to claim 2, wherein said substrate is a glass substrate. 4. A semiconductor device comprising: a first substrate; a second substrate; and a liquid crystal sandwiched between the first substrate and the second substrate. A liquid crystal display device comprising: a gap forming layer provided between the substrate and the substrate; and a gap for enclosing the liquid crystal is provided by processing the gap forming layer. 5. A liquid crystal display device according to claim 2, wherein said processing is etching or sandblasting. 6. The liquid crystal display device according to claim 1, wherein said gap is provided for each signal line or each pixel.