JPS61160719A - Liquid crystal display panel - Google Patents

Abstract

PURPOSE:To maintain the specified spacing on a substrate side even if the transparent substrates themselves have some non-flatness owing to waving ruggedness by using the resilient substrate for one of the transparent substrates. CONSTITUTION:The hard glass substrate 1 is used for one of the two light transparent substrates, for example, glass substrates 1, 1' and a glass plate or org. resin 1' which is semi-hard to the extent of permitting bending when the spacing between the substrates is evacuated is used for the other. Prescribed electrodes for a liquid crystal are formed of light transparent conductive films 2, 2', for example, ITO or SnO2 on one side of the respective substrates. Polyimide resins 3, 3' are thinly formed atop said films and are subjected to an orientation treatment by a known rubbing treatment.

Description

Detailed Description of the Invention Field of Application of the Invention The present invention relates to a liquid crystal display panel or an active matrix type liquid crystal display panel, and the present invention relates to a liquid crystal display panel or an active matrix type liquid crystal display panel, which is used to reduce the thickness of a display unit of a microcomputer, word processor, television, etc. Regarding equipment.

rPrior art j Regarding a conventional liquid crystal display device, a transparent conductive film and an alignment film are provided on the inside of two transparent substrates, and liquid crystal is filled between the two transparent substrates to determine whether or not a voltage is applied between the two electrodes. ``On'' and ``Off'' were controlled by This display displays characters, graphs, or pictures.

However, the distance between these two transparent electrodes is only about 10 microns, and recently this thinness has been required to be about 5 microns or less. It has been extremely difficult to construct large-area electrodes or a large number of dotted active matrix electrodes without any electrical short-circuits, separated by such a small gap.

For this reason, spacers were devised to control this gap. That is, the spacer is generally a spherical particle of organic resin, for example, Microvar 5P-210 (average particle size 1).
0.0±0.5μ) is used. These micropearls are divinylbenzene-based crosslinked polymers and are transparent pearl particles.

That is, FIG. 1 shows a vertical cross-sectional view of a conventional liquid crystal display device. In the drawing, two transparent substrates (1
), (1"), a sealing material (6) made of a mixture of resin and spacer (7) is placed around the area to prevent the liquid crystal from leaking to the outside.
is stored to keep the distance between the two substrates constant at the periphery. However, the display part (lO), that is, the liquid crystal (5)
In the region filled with , the two transparent electrodes tend to be short-circuited or come close to each other due to external mechanical stress on the transparent substrate or due to the flatness of the substrate. As a result, the liquid crystal loses its translucency or becomes partially black, which tends to cause defects. For this reason, other spacers (4) are also scattered around the liquid crystal section to keep the respective electrodes at a constant distance so as not to short-circuit.

``The problem that the invention aims to solve'' However, when trying to actually make a liquid crystal display device, after sealing the two substrates with a sealant except for a part of the periphery, the inside of the substrate is kept in a vacuum, and the capillary This phenomenon is used to charge the liquid crystal. However, it was observed that this filling was not always uniform. In particular, even if the spacers were to be randomly and uniformly scattered, they tend to aggregate because they are extremely small, and in reality they are unevenly distributed in some areas. Further, when the temperature of the display device increases after sealing, the substrate tends to swell due to thermal expansion of the liquid crystal itself, making it impossible to maintain a constant distance between the two electrodes. For this reason, a phenomenon has been observed in which the contrast of the display differs between the center and the periphery. Particularly when the display device was in the form of a large panel measuring 20 cm x 30 cm, defects were likely to occur.

Therefore, in the present invention, the spacer does not have a spherical shape, but has a rectangular shape (preferably a dice-shaped cube), and the contact between the spacer and the alignment film is controlled by the spherical spacer. Instead of point contact, we used square spacer surface contact. Furthermore, when the liquid crystal is in the form of a sphere, the occurrence of local defects due to unfilling in the vicinity of the alignment film is prevented.

In addition, the surface of this spacer is covered with a polyimide resin made of the same material as the alignment film, and the spacer, upper alignment film, and lower alignment film are adhered to each other (including welding or adhesion) using the same polyimide. .

``Operation'' By doing this, even if the two substrates themselves have some unevenness due to undulations in the initial stage, when the peripheral parts are sealed with the sealing material and then vacuumed, each The gap on the substrate side can be made constant by increasing the size and height of the spacer. In this state, the spacer and the opposing alignment film are brought into close contact with each other by the resin coating the spacer, and the gap therebetween is solidified.

For this reason, even if the vacuum is removed afterwards, the respective substrates are substantially in close contact with each other due to the spacers, so they do not return to their original non-flat state, and the gap between the electrodes becomes constant, resulting in the final state. , there will be no problems such as parts of the panel being too wide. In addition, because the substrates are brought into close contact with each other using spacers, the mechanical strength of the display panel itself is not as strong as that of only one panel, but is similar to that of laminated glass, making it possible to have a mechanical strength that is essentially equivalent to the strength of two panels. It became.

The present invention will be described below according to examples.

Example 1 FIG. 2 is a vertical cross-sectional view of a liquid crystal display device of the present invention, and FIG. 3 is a vertical cross-sectional view showing the manufacturing process thereof.

In the drawing, two transparent substrates, e.g. glass substrates (
1), (1') One was a hard glass substrate (1), and the other was a semi-hard glass plate or organic resin (1°) that could be bent when the gap was evacuated.

A predetermined liquid crystal electrode was formed on one surface of each of the substrates using a transparent conductive film (2) (2°) of, for example, TTO or SnO□. Polyimide resin (3) on this top surface
.

(3゛) was formed into a thin film, and the orientation treatment was removed by a known rubbing treatment. Next, as shown in FIG. 3(A), an ultraviolet curable polyimide solution (15) in which porous rectangular spacers are dispersed is applied to the upper surface of one side using a spinner, roll coater, spray method, or screen printing method. do.

This polyimide solution is a wholly aromatic polyimide precursor solution, and as an example, Photonice sold by Toshi Co., Ltd. was used.

Further, CaSnO2 was used as the rectangular spacer. This compound has a porous rectangular tetragonal crystal type, and the size of the side thereof can be made arbitrarily within the range of 1 to 10 μm. For example, it was set to 5μ±0.5μ.

Impregnation of polyimide into the pores of this spacer is as follows. That is, a spacer was placed in the container, and the container was evacuated. Then, the gas inside the pores was degassed. Further, while maintaining this vacuum, the polyimide solution described above was mixed into the container so that a portion of the polyimide was impregnated into the pores.

After this, the container was brought to atmospheric pressure and impregnated.

Furthermore, after applying the polyimide solution mixed with this spacer as shown in FIG. 3(A), prebaking was performed at 80'C.
It lasted 60 minutes.

By diluting this precursor solution, it is possible to save on the amount of polyimide solution needed to fix the spacer.

Furthermore, after this prebaking, as shown in FIG. 3(B),
A mask (16) was used. This mask has light-transmitting windows (17) of about 100 μm at regular intervals, for example, every 30 μm. Thereafter, ultraviolet light (20) was exposed through this mask (10 mW/cmz light for about 30 seconds). The mask may be applied from below as shown in the drawings or from above the substrate.

Then, the electrode of one liquid crystal of the active element is 400μ
If it is a mouth, it is an area without active elements,
It becomes possible to arrange approximately 1 to 4 rectangular spacers in an area of 30 μO provided on each electrode.

That is, it becomes possible to arrange the spacers in a scattered manner with substantially a predetermined interval between the spacers.

Further, with this mask, in the case of an active type liquid crystal panel, areas where wiring, non-linear elements, or switching elements are present can be intentionally avoided. That is, the spacer can prevent the possibility that the leads will break due to mechanical stress or the like, or that the element will become inoperable during subsequent use.

After this, development was carried out by an ultrasonic development method at 25° C. for 25 minutes using a specified DV-140. Furthermore, ultralong wave rinsing was performed with isoparonol at 25° C. for 15 seconds.

Thus, as shown in FIG. 3(C), the transparent substrate (1)
A rectangular spacer (14) with the polyimide resin (18) remaining in close contact with the upper translucent conductive film and the polyimide alignment film (3) thereon can be disposed at approximately a predetermined position. Ta.

Next, as shown in Figure 2, a transparent electrode (2"), an alignment film (
After coating the periphery of the opposed translucent glass (1") with a glass plate (3") provided on the inside, a sealing material was applied, and the gap was evacuated at the same time as the pressing. In this state, post-bake 2 times.
The temperature was 00 to 300°C. Then, the polyimide remaining on the surface of the spacer came into close contact with the polyimide alignment film of the opposing glass, making it possible to bond the two glasses together.

In this case, if the opposing glass is semi-hard, the other glass will be aligned with the distortion of the glass itself and will be fixed together using the spacer, causing the glass substrate itself to become distorted (smooth Even if the electrodes have irregularities (concavities and convexities), the electrode gaps can be kept constant regardless of the irregularities, and the opposing glasses can be substantially bonded to each other.

In the embodiment of the present invention, the gap held by the spacer was then filled with liquid crystal (5) by a known method.

Effect j As described above, in the present invention, in order to make the gap between two opposing electrodes constant, the upper and lower alignment films are brought into close contact with each other using spacers of the same size.As a result,
The distance between the two alignment films could be kept constant within the range of a predetermined thickness ±0.5μ. In particular, 20c+ has an active matrix structure and has a dot count of 400 x 1920.
In a liquid crystal panel with a large area of m x 30 cm, it was possible to prevent the central part from expanding more than necessary or the two electrodes from coming close to each other.

For this reason, in the past, if a liquid crystal was manufactured using large-area substrates, each substrate had to be polished extremely precisely. However, the present invention has another feature in that there is no processing step that is 2 to 5 times as expensive as the price of such a glass substrate.

In addition, since one to several spacers are provided at a distance of approximately 400 μm, the liquid crystal panel can now be handled as an extremely strong substrate similar to so-called laminated glass.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal sectional view of a conventionally known liquid crystal display device. FIG. 2 shows a longitudinal sectional view of the liquid crystal display device of the present invention. FIG. 3 shows the manufacturing process of the liquid crystal display device of the present invention.

Claims (1)

[Claims] 1. A liquid crystal display panel comprising two transparent substrates each having a transparent electrode and an alignment film on the inside, interposing a spacer between two opposing transparent substrates, and filling liquid crystal between the substrates, A liquid crystal display panel characterized in that one of the transparent substrates has flexibility. 2. The liquid crystal display panel according to claim 1, wherein one of the light-transmitting substrates is flexible.