JPH112808A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the liquid crystal display device which eliminates the need to form another structure as a spacer and has superior display performance by making the height of crossing lattices of a black structure forming a black matrix equal to the cell interval of liquid crystal in one direction and less in the other direction. SOLUTION: Two substrates 1 having an electrode 4 and an orientation film 5 formed are stuck together having a certain interval, and liquid crystal is injected into the part between them to form a liquid crystal layer 6. Here, the substrate 1 where the black matrix consisting of the black structure so that the height of the crossing lattices 7 and 8 in one direction is equal to the liquid crystal cell interval and the height in the other direction is less than it is formed and the counter substrate are stuck together. Further, the height of the crossing lattices 7 and 8 in one direction is make >=1 μm less than the height in the other direction. The light shield property of the lattice type structure forming the black matrix is preferably larger than an OD value 2.

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 widely used for a light control device and a display device.

[0002]

2. Description of the Related Art A thin film transistor type liquid crystal display (TFT-L), which is the center of a color liquid crystal display, will be described below.
The flow of the manufacturing process of CD) will be briefly described.

First, a TFT substrate and a color filter (C
An alignment film is formed on each of F). This alignment film, after washing each substrate, usually produces a polymer film such as polyimide on the substrate by a flexographic printing step and a subsequent curing step, and rubs the film in one direction with a cloth such as rayon, The formation is completed by a so-called rubbing treatment.

[0004] Further, after each substrate is washed, a spacer such as a glass fiber equal to a desired liquid crystal cell interval is sprayed on one of the substrates, and a spacer such as a glass fiber is used as a sealing material on the other substrate. A predetermined amount is uniformly mixed and applied in a predetermined pattern. The sealing material pattern is a rectangle with a liquid crystal inlet,
A pattern frame having the same width is formed by a screen printing method.

[0005] Then, the TFT substrate and the color filter substrate are bonded together. The bonding step is a step of bonding the TFT substrate and the color filter substrate accurately using the alignment mark, and then baking under pressure to cure the sealing material while maintaining the gap between the substrates. .

The subsequent liquid crystal injection step is a step of injecting liquid crystal into the completed empty panel by a vacuum injection method, sealing the injection port with an adhesive, and completing the liquid crystal panel.
For vacuum injection, first, the injection tank is evacuated to about 10 ^-3 Torr, then the empty panel is immersed in the liquid crystal reservoir installed in the tank, and the inside of the tank is gradually leaked to inject the liquid crystal into the empty panel. In principle, the principle is the use of capillary action due to pressure differences. The sealing of the injection port is performed by applying an ultraviolet curing resin to the injection port and irradiating the portion with ultraviolet light to cure the resin.

The above process flow is a manufacturing process of a TFT-LCD, which is a general method of manufacturing a color liquid crystal display device.

The cell interval of the liquid crystal display device, that is, the interval between the two substrates has an optimum value corresponding to the anisotropy Δn of the refractive index of the liquid crystal to be used, and the TN used for the TFT type liquid crystal display device. In the case of a liquid crystal of the type, it is set to 4 to 6 μm. In order to maintain such cell spacing, spacers made of glass beads are sprayed on the substrate, and then the periphery of the substrate is fixed with a sealant. It is only fixed by the seal part, and the cell gap fluctuates even under the application of a weak pressure such as pressing with a finger.Therefore, in applications where the substrate surface is pressed such as a touch panel, It was necessary to separately stack a touch panel substrate on the liquid crystal display device.

Further, in the method of spraying spacers made of glass beads, the spacers are scattered non-uniformly, and light is leaked because the liquid crystal does not exist in the spacer portion, thus causing a decrease in contrast.

On the other hand, a method has been considered in which a columnar structure is formed on one of the substrates as a spacer at a desired cell-interval height, and this is used as a spacer to bond two substrates. In this method, the columnar structure is installed so as to overlap the position of the black matrix of the color filter so as not to lower the aperture ratio of the display pixel. However, if the same lattice pattern as that of the black matrix is completely formed, each pixel is partitioned by the columnar structure, so that liquid crystal cannot be injected.

Therefore, the spacer of this type must be formed in a stripe shape or a dot shape, and a black matrix is separately formed on a substrate, and the process becomes complicated, so that it has not been put to practical use.

[0012]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems.
Without using expensive glass fiber or other particle-based spacers,
It is an object of the present invention to provide an inexpensive and high-quality liquid crystal display device having a simple and accurate thickness designed in a free range according to the characteristics and driving method of a liquid crystal to be used.

[0013]

According to the present invention, there is provided a liquid crystal display device in which two substrates having electrodes and an alignment film formed thereon are adhered at a predetermined interval, and liquid crystal is injected into the substrates. In the liquid crystal display device, a black matrix composed of a black structure was formed such that the height of one of the intersecting gratings in one direction was equal to the desired liquid crystal cell interval and the height in the other direction was lower than that. A liquid crystal display device comprising a substrate and a counter substrate bonded to the substrate.

Further, according to the present invention, in the liquid crystal display device according to the first aspect, the height in one direction of the grid intersecting the black matrix is 1 μm or lower than the height in the other direction. It is.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid crystal display device of the present invention is mainly composed of upper and lower substrates (in the case of a thin film transistor type liquid crystal display device TFT-LCD, upper substrate: color filter, lower substrate: TFT (A substrate) is coated with a polymer orientation film such as polyimide, and then rubbed in one direction by rubbing it with a cloth of fiber such as rayon. It is produced by a process of bonding through a liquid crystal panel and a process of injecting and sealing a liquid crystal into the formed empty panel.

In the case of the present invention, in the bonding step, instead of using a particle-based spacer, a resin lattice-like structure formed by patterning and curing is used. The control of the thickness of the panel, which has been limited by the type of the particle size, can be performed more easily.

That is, first, a transparent electrode is formed, and a black photosensitive resin is applied on the substrate on which the alignment film is applied so as to have a desired thickness between cells. Next, exposure and development are performed according to a standard method to form a stripe pattern in only one direction of a lattice of a black matrix. Next, a black photosensitive resin is applied again. In this case, the coating film thickness is made thinner by 1 μm or more than a desired cell interval. The lower limit of the film thickness may be a thickness at which a required black OD value can be obtained, and may be determined according to the light-shielding property of the black photosensitive resin so as to obtain an OD value of 2 or more. The substrate is again exposed and developed to form the remaining pattern of the black matrix. Further, a rubbing process is performed on this substrate, the substrate is bonded to a counter substrate coated with a sealant around the periphery, baked while applying pressure, and the sealant is cured to form an empty panel.
Liquid crystal is injected into the empty panel, and the injection port is sealed to complete the liquid crystal display device.

The black matrix used in the liquid crystal display device of the present invention can be manufactured by the following method in addition to the above method. First, a transparent electrode is formed, and a negative type black photosensitive resin is applied to the substrate on which the alignment film is applied so as to have a thickness of a desired cell interval. Next, according to a standard method, only one direction of the lattice of the black matrix is exposed. Next, the remaining pattern of the black matrix is exposed with a reduced exposure amount so that the film thickness after development is 1 μm or more smaller than a desired cell interval. If development is performed thereafter, the black matrix of the present invention can be formed by one coating and development.

It is also possible to first form a black matrix with a thickness equal to the cell interval, and then etch only one direction of the lattice by 1 μm or more using a method such as etching to complete the black matrix. is there.

Since a black structure used as a black matrix is in contact with liquid crystal, it is necessary that ionic substances and the like do not elute into the liquid crystal. However, it is usually used as a black matrix for a color filter. If such a black photosensitive resin is used, such a problem does not occur.

In the liquid crystal display device of the present invention, the height in one direction of the intersecting lattice of the black structure forming the black matrix is equal to the cell interval of the liquid crystal, and the other is lower than that. Therefore, when an empty panel is formed, the liquid crystal can be easily injected by vacuum injection through the gap between the counter substrate and the black matrix as in the related art, and the cell interval does not fluctuate. The height of the intersecting grid in one direction is 1 more than the height in the other direction
It is necessary to lower the height by at least μm.

Further, by providing the grid-like structure with a light-shielding property, the step of forming a black matrix on the color filter can be omitted, and the bonding accuracy between the color filter substrate and the TFT substrate can be improved.
The light-shielding property of the lattice structure is preferably 2 or more in OD value.
As described above, according to the present invention, an inexpensive and high-quality color liquid crystal display device can be realized.

Further, in the liquid crystal display device of the present invention, since the cell spacing is maintained by the columnar structure of the black matrix, the cell spacing does not change even when the panel is pressed.

[0024]

Embodiments of the present invention will be described below. First, a TFT substrate and a color filter were prepared, and they were subjected to ultrasonic cleaning while being immersed in acetone, ethanol, and pure water in this order for several minutes. Next, a polyimide film (LQ-T120 manufactured by Hitachi Chemical Co., Ltd.) was formed on those substrates with a thickness of 0.1 μm. Subsequently, rubbing was performed on each substrate in a predetermined direction.

Next, the same cleaning as the previous cleaning is performed, and TF
On a T substrate, a sealing material (Struct Bond XN-21-S manufactured by Mitsui Toatsu Chemicals Co., Ltd.) is applied and formed (0.3 mm in width) by a screen printing method using a predetermined plate pattern.
On the other hand, 142 parts by weight of ethyl cellosolve as a black photosensitive resin and a binder resin (butyl methacrylate / methacrylic acid / acrylic acid =
50:30:20 copolymer) 30 parts by weight, black pigment (carbon black) 10 parts by weight, monomer (Toagosei Co., Alonix M-310) 15 parts by weight, initiator (Ciba Geigy Co., Irgacure 907) 3 The black photosensitive resin composition in parts by weight was coated to a thickness of 4.5 μm by spin coating.
And using two predetermined masks
Double exposure was performed and development was performed to form a black matrix having a height of 4.5 μm in one direction of the intersecting grid and 3.0 μm in the other direction.

Then, the color filter substrate and the TFT substrate are attached to each other, and are pressed while using a predetermined jig.
After baking at 0 ° C. for 1 hour and slow cooling, the completed empty panel was taken out, and liquid crystal (Merck ZLI-4792) was injected under vacuum.
-2110) to complete a good color liquid crystal display device having a thickness of 4.5 μm, which is uniformly controlled and has no display unevenness. Even when the device was pressed with a finger, no display unevenness due to a change in cell interval was observed.

[0027]

As described above, according to the liquid crystal display device of the present invention, a black matrix consisting of a lattice-like structure having a predetermined pattern is formed and cured to form a spacer,
By bonding the substrates on which the sealing material is applied in a predetermined pattern to each other, a liquid crystal display device in which the cell interval does not fluctuate even when pressed, particularly on a touch panel, can be realized. Further, in the liquid crystal display device of the present invention, since the black matrix has a spacer function for maintaining the cell interval, it is not necessary to form another structure as a spacer. Further, a liquid crystal display device having excellent display performance without light leaking from the spacer portion was realized.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view showing a surface structure of a liquid crystal display device of the present invention.

FIG. 2 is a schematic explanatory view showing a sectional structure of the liquid crystal display device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Color filter substrate 2 ... Seal part 3 ... Liquid crystal injection port 4 ... Color filter substrate electrode 5 ... Alignment film 6 ... Liquid crystal layer 7 ... Resin lattice structure (black matrix spacer) 8 ... Resin lattice structure (Black matrix)

Claims (2)

[Claims] 1. A liquid crystal display device comprising two substrates on which electrodes and an alignment film are formed, which are bonded at a predetermined interval, and into which a liquid crystal is injected. A substrate on which a black matrix made of a black structure is formed, in which the height in one direction is equal to a desired liquid crystal cell interval and the height in the other direction is lower than that, and an opposing substrate is attached to the substrate. A liquid crystal display device formed together. 2. A liquid crystal display device according to claim 1, wherein the height in one direction of the grid intersecting the black matrix is lower than that in the other direction by 1 μm or more.