JPH02199427A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To assure the uniformity of a gap even with the large-area liquid crystal display device and to improve display quality and productivity by providing adhesive bodies in the contact parts of spacers and the inside surface of at least one plane substrate of two sheets of the plane substrates. CONSTITUTION:The spacers 104 are applied and formed by a spin coating method on the surface of a liquid crystal oriented film 103 and the adhesive bodies 109 are formed by a roll coating method only in the top parts of the spacers 104. The material of the adhesive bodies is a thermosetting resin of an epoxy system. The two substrates 101, 105 are press-welded and while a peripheral sealant as well as the spacers 104 and the adhesive bodies 109 are held crushed, the adhesive bodies are cured by heating at the time of sticking the substrates. The adhesive bodies 109 are partly extruded from between the upper substrate 105 and the spacers 104 and are solidified. The spacers 104 are previously disposed between adjacent horizontal electrodes and between adjacent vertical electrodes and to not exist in the regions where picture elements are formed. The thickness (gap) of the liquid crystal layer 108 is uniform in conformity with the size of the spacers 104.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a spacer for controlling the gap of a liquid crystal display in a large-area, high-definition liquid crystal display.

[Prior art] In recent years, a great deal of effort has been devoted to the technological development of liquid crystal display devices, and C.
It has become possible to realize a liquid crystal display device with screen size, resolution, and image quality comparable to RT. However, there are still some issues to be solved before this liquid crystal display device can be produced industrially and efficiently. One of these is the issue of gap control. Gap unevenness in liquid crystal display devices has a large effect on display quality. For example, in the case of a TN-type liquid crystal display device, if the gap becomes non-uniform, a portion of the screen may become discolored due to the effect of retardation, and display quality may deteriorate, such as a reduction in contrast. This effect is ST
This is particularly noticeable in liquid crystal display devices with a large twist angle, such as N-type. Furthermore, the larger the screen size, the more difficult it is to make the gaps uniform, and the higher the resolution, the more noticeable the reduction in contrast due to uneven gaps becomes.

By the way, the gap control technology of conventional liquid crystal display devices is
As shown in Figure 3, spacers made of glass fiber or microbar are spread between two flat substrates, and the periphery of the flat substrates is adhesively fixed with a sealant containing spacers to form a liquid crystal layer. The thickness was controlled.

[Problems to be Solved by the Invention] However, the above-mentioned prior art has important problems as listed below. In other words, (1) because the sealant is formed only on the periphery of the flat substrate for bonding, a gap bulges in the center of the flat substrate due to the difference in the coefficient of thermal expansion of the flat substrate, making it difficult to seal the liquid crystal. Later, unevenness of gatsu appears on the periphery and center.

(2) The above-mentioned spacer in the bulge in the center is swept away by the fluidity of the liquid crystal when it is sealed, and the density of the spacer partially changes, resulting in unevenness of the gap.

(3) When the area of a flat substrate is increased to form a large-screen liquid crystal display device, unevenness in the gap occurs due to the surface waviness of the normally existing flat substrate.

etc.

Therefore, the present invention is intended to solve the problems of the prior art, and its purpose is to maintain gap uniformity even in large-area liquid crystal display devices, thereby improving display quality. The purpose is to provide a liquid crystal display device with excellent productivity.

[Means for Solving the Problems 1] The liquid crystal display device of the present invention includes two planar substrates that face each other, and a spacer that is inserted between the two planar substrates and holds the inner surfaces of the two planar substrates in parallel. , Previous iiiE! In a liquid crystal display device having at least a component of a liquid crystal sealed between two flat substrates, an adhesive is provided at a contact portion between the spacer and an inner surface of at least one of the two flat substrates. It is characterized by

[Example] The present invention will be explained in more detail based on examples.

Embodiment 1 FIG. 1 is a schematic cross-sectional view of a TN simple matrix liquid crystal display device for explaining a first embodiment of the present invention. The structure of this liquid crystal display device includes a transparent flat glass substrate 101, strip-shaped horizontal electrodes 102 made of an ITO thin film formed on the surface thereof, and formed on the exposed surface of the flat glass substrate 101 and the surfaces of the horizontal electrodes 102. a lower substrate consisting of a liquid crystal alignment film 103 and a spacer 104 formed on the surface of the liquid crystal alignment film; and a transparent flat glass substrate 10.
5. A striped vertical electrode 106 made of an ITO thin film formed on its surface and an upper substrate made of a liquid crystal alignment film 107 formed on these surfaces are bonded together, and a sealing agent is formed around these parts. and spacer 104
It has a structure in which a liquid crystal 108 is sealed in a liquid crystal cell by adhesively fixing it with an adhesive body 109 formed at the top of the liquid crystal cell.

A method for forming the liquid crystal alignment film 103, spacers 104, and adhesive body 109 that are previously formed on the lower substrate will be described. First, the liquid crystal alignment film 103 is formed by coating the alignment film raw material JIB-29 (manufactured by Japan Synthetic Rubber) on the surface of the flat glass substrate 101 on which the horizontal electrodes 102 are formed using a spin code method.
It is formed by curing at 200°C for 1 hour. The spacer 104 is made of photosensitive polyimide raw material PI-410 (manufactured by Ube Industries) by spin coating on the surface of the liquid crystal alignment film 103 mentioned above.
After coating, prescribed prebaking, exposure, and development are performed, and finally, curing is performed at 200° C. for 1 hour to form the film. The height of the spacer 104 is 5.8 μm. Also,
The adhesive body 109 is formed only on the top portion of the spacer 104 described above by a roll coating method. The material of the adhesive body is an epoxy thermosetting resin, and the film thickness on the roll is about 1 μm. However, the material and film thickness of the adhesive body need not be limited to these, for example, a photocurable resin may be used, and the film thickness may be within the height of the spacer.

When the upper and lower substrates are bonded together, both substrates are pressure-bonded and the sealant and adhesive are heated and cured while being crushed, so a portion of the adhesive 109 is pushed out from between the upper substrate and the spacer, causing the first As shown in Figure 1, it solidifies near the contact area between the spacer and the upper substrate. In addition, the spacer is pre-arranged between adjacent horizontal electrodes and between adjacent vertical electrodes, and it hardly invades the area that will actually become a pixel, and the area where the adhesive body 109 is formed is also in the initial stage of the adhesive body. Since it is the same if the volume of is selected, the present invention does not cause a decrease in pixel area.

The liquid crystal display device manufactured in this way has a display area of 1 inch diagonally, is an STN type, has a gap unevenness of 58 μm±01 μm, and has a contrast of 1.1 μm.
5, which was extremely good. This reflects the fact that at each spacer, the upper and lower substrates are adhesively fixed while maintaining a gap determined by the height of the spacer, so the gap is uniform throughout the liquid crystal cell. .

Although this embodiment has been described with respect to a TN type simple matrix type liquid crystal display device, it is of course applicable to a type other than the TN type or an active matrix type.

<Example-2> Figure 2 is for explaining the second example of the present invention, and is a schematic cross-sectional view of a cholesteric-nematic phase change type or capsule type liquid crystal display device that does not require alignment treatment. It is. On the surface of the transparent flat glass substrate 201,
Striped horizontal electrodes 202 and transparent adhesive 203
a lower substrate formed with a striped vertical electrode 205 and a transparent adhesive 2 on the surface of a transparent flat glass substrate 204.
06 is bonded to the upper substrate with a spacer 207 and a liquid crystal 208 interposed therebetween.

At this time, the adhesive bodies formed on the surfaces of the upper and lower substrates and the spacer are adhesively fixed, and the thickness (gap) of the liquid crystal layer is made uniform according to the size of the spacer. The adhesive is formed on the surfaces of the upper and lower substrates by a coating method, and is solidified by pressing the two substrates together with a spacer in between.

This liquid crystal display device is suitable for a phase change type because it is difficult to perform alignment treatment such as rubbing on the surface of the adhesive.

[Effect of the invention] The present invention has the effects of the invention listed below.

(11) Even in a liquid crystal display device using a large-area flat substrate, a uniform gap can be obtained, and the liquid crystal display device has excellent display characteristics and productivity.

(2) Even if the raw material flat substrate has some waviness, a uniform gap can be obtained, so using an inexpensive raw material substrate,
A high quality liquid crystal display device can be obtained.

(3) It is a highly reliable liquid crystal display device with little change in gap uniformity due to heat or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a liquid crystal display device for explaining a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a liquid crystal display device for explaining a second embodiment of the present invention. FIG. 3 is a schematic diagram of a conventional liquid crystal display device. 108 ・ 109 ・ 201. 202 ・203. 205 ・ 207 ・ 208 ・ Vertical electrode liquid crystal adhesive flat glass substrate Horizontal electrode adhesive vertical electrode spacer Liquid crystal Applicant Seiko Epson Corporation Agent Patent attorney Homare Kamiyanagi (1 person) 101.1
05... Flat glass substrate 102... Horizontal electrode 103.107... Liquid crystal alignment film 104... Spacer Fig. 3

Claims (1)

[Claims] Consists of at least two opposing planar substrates, a spacer inserted between the two planar substrates to hold the inner surfaces of the two planar substrates in parallel, and a liquid crystal sealed in the middle of the two planar substrates. A liquid crystal display device as an element, characterized in that an adhesive is provided at a contact portion between the spacer and an inner surface of at least one of the two planar substrates.