JPH04243229A - Liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve hermeticity by constituting sealing layers of plural sealing layer lines. CONSTITUTION:Driving electrodes 2 and oriented films 3, etc., are formed by using two sheets of glass substrates 1 and thereafter, two pieces of the sealing layers 5a, 5b are applied and formed in the regions intruding inward from the peripheral part of the one substrate 1 except the liquid crystal injection port 15. These layers are then cured by heating. An adhesive material of an epoxy resin system which is intimately mixed with spacers, for example, glass fiber pieces, is used as the sealing layer material in such a case and is automatically and successively applied by a dispenser device. Further, the sealing layer is predried after the application. The substrate is stuck to another substrate 1 sprayed separately with the spacers in the display part upon ending of predrying and the sealing layers are cured by heating in a pressurized state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid crystal display panels. Specifically, it is designed to prevent air bubbles from becoming trapped in the sealing layer of the liquid crystal display panel, and to reduce the occurrence of inspection omissions due to trapped air bubbles, thereby improving quality and yield. Related to liquid crystal display panels.

0002

BACKGROUND OF THE INVENTION In recent years, improvements and widespread use of liquid crystal display devices have been remarkable, and demands for higher definition and larger screens have become stronger. In line with this, there is a need for more sophisticated panel forming technology for liquid crystal display panels, such as a seal layer forming technology for forming a liquid crystal sealed space airtight and an easier inspection thereof.

FIG. 4 is a diagram showing an example of the configuration of a liquid crystal display panel, and is an example of a simple matrix type liquid crystal display panel.
Figure (a) is a perspective view, and figure (b) is a side sectional view. In the figure, 1 is a transparent electrode, 2 is a striped drive electrode formed on the transparent electrode 1 and made of, for example, an ITO (In2O3-SnO2) film, and 3 is an alignment film, for example, a polyimide resin film is After coating the entire surface of the transparent substrate 1 on which the electrodes 2 are formed, a rubbing treatment is performed to impart orientation to the liquid crystal molecules. 4 is a liquid crystal, for example, STN (SUPER Twisted Nemat
IC) type liquid crystal.

The two substrates on which the driving electrode 2 and the alignment film 3 are formed are arranged so that a narrow space (5 to 10 μm) is formed with the alignment film surface in the middle, as shown in FIG. The periphery of the stacked substrates is hermetically bonded with a seal layer 5' with a spacer (not shown) in between, and liquid crystal 4 is injected and sealed into the space to constitute a simple matrix type liquid crystal display panel. In the case of other active matrix type liquid crystal display panels, the process of sealing two substrates is almost the same.

FIG. 5 is a diagram showing an example of a conventional sealing layer application pattern and a cross-sectional example of a sealing part.
B) is a cross-sectional view taken along line AA', and (c) is a cross-sectional view taken along line B-B'. In the figure, 15 is an injection port for injecting the liquid crystal 4, and 150 is a bubble remaining in the sealing layer. In addition, parts equivalent to those explained in the above drawings are designated by the same reference numerals.
Furthermore, explanations of equivalent parts will be omitted.

Normally, a sealing layer 5' is formed on one of the two substrates by a thickness of 0.5 mm at the peripheral edge of the substrate, as shown in FIG.
It is applied to a width of about mm and a thickness of several μm, and spacers are sprinkled on the display area of the other substrate, and both substrates are bonded together.

The adhesive is an epoxy resin adhesive mixed with a spacer of several μm in size, such as a piece of glass fiber or fine particles made of synthetic resin. Cure for about 1 hour. In this case, the seal layer generally has a milky white color.

[0008] The sealing layer 5' can be applied, for example, by using a dispenser or by screen printing.
Since the adhesive contains a considerable amount of solvent, even if the adhesive is thoroughly degassed in advance, air bubbles 150 as shown may be generated and remain in the sealing layer. Therefore, before bonding the substrate on which the seal layer 5' has been formed, or after bonding and before injecting the liquid crystal, light is applied from below the seal layer, and the seal layer is inspected using a microscope, for example, to detect air bubbles 150. If there is such a problem, the product is rejected as defective.

Note that an injection port 15 for injecting the liquid crystal 4 is provided in a part of the sealing layer 5', and after the two substrates are bonded and the liquid crystal 4 is injected, a separate adhesive, for example, It is sealed with an acrylic resin-based UV-curable adhesive.

0010

[Problems to be Solved by the Invention] However, in the case of the above-mentioned conventional sealing layer, air bubbles are generated after the resin that is the material of the sealing layer hardens, and when these air bubbles penetrate the width direction of the sealing layer, the airtightness within the liquid crystal display panel is impaired. can no longer be held and the liquid crystal cannot be injected and sealed.

[0011] Furthermore, the material for the sealing layer generally uses an epoxy resin adhesive, and is usually white or milky white. Furthermore, since the thickness of the seal layer is as thin as 5 to 10 μm, it has high light transmittance, and when the seal layer is inspected with a microscope, for example, when light is applied from below, the seal layer becomes almost translucent. There is a problem in that the difference between the bubbles and the bubbles contained therein is not clear, and defects such as bubbles are often overlooked, resulting in poor airtightness of the liquid crystal display panel, and a solution to this problem is required.

0012

[Means for Solving the Problem] The above problem is solved by bonding two transparent substrates 1 on which at least a drive electrode 2 and an alignment film 3 are laminated with a sealing layer 5 in between so that a certain gap is formed. In a liquid crystal display panel formed by injecting and sealing the liquid crystal 4 into the gap, the problem can be solved by a liquid crystal display panel in which the seal layer 5 is composed of a plurality of seal layer lines. Furthermore, the problem can be effectively solved by configuring the seal layer 5 made up of the plurality of seal layer lines to be composed of a seal layer 5a line including at least one spacer and a seal layer 5c line not including a spacer. can.

Furthermore, the problem can be solved more efficiently and effectively by using a liquid crystal display panel in which the sealing layer 5 is colored in a color other than white.

[0014]

[Function] According to the present invention, since the sealing layer 5 is composed of a plurality of sealing layer wires, the width of each sealing layer can be narrowed, and the solvent can be easily removed after the sealing layer material is applied, so that air bubbles are formed. In addition to reducing the occurrence of bubbles, by using a plurality of bubbles, the probability of airtightness deterioration due to bubble generation can be reduced. Furthermore, although air bubbles are generally often taken in when mixing spacers, such air bubbles do not exist in the seal layer 5c line that does not include a spacer, so the composite seal layer line structure improves airtightness.

Furthermore, by coloring the sealing layer 5 in a color other than white, bubbles contained in the sealing layer can be easily identified, thereby shortening inspection time and reducing defects.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a seal layer coating pattern according to a first embodiment of the present invention. In the figure, 5 is a sealing layer, 5a, 5
b is a seal layer line forming the seal layer 5.

[0017] The same parts as those explained in the above drawings are given the same reference numerals, and the explanation of the same parts will be omitted. 350 x 400 m as substrate 1
After forming drive electrodes 2 and alignment films 3 on each of the two glass substrates 1, a liquid crystal injection port 15 is inserted into an area approximately 10 mm from the periphery of one of the substrates 1.
After forming the two seal layer lines 5a and 5b by coating except for the portions indicated by , they are heated and cured.

The material for the sealing layer is an epoxy resin adhesive mixed with a spacer of about 5 μm, for example, a piece of glass fiber, and is automatically applied by a dispenser device. The amount of application is adjusted by the dispenser pressure, for example, with a nozzle diameter of 0.25 mm.
When the distance between the nozzle tip and the substrate is 50 μm, a seal layer line with a width of about 0.5 mm is formed at an air pressure of 2 kg/cm2. In this example, the width of each seal layer line is 0.25 mm, and the gap between the seal layer lines is 0.1 mm.
And so.

After applying the seal layer, preliminary drying is performed on a hot plate at 100° C. for 5 minutes. After the pre-drying is completed, the display area is bonded to the other substrate on which spacers have been separately sprinkled, and heat-cured under pressure at 150°C for 1 hour.
A liquid crystal display panel is manufactured.

FIG. 2 is a diagram showing a seal layer coating pattern according to a second embodiment of the present invention. In this embodiment, one of the two seal layer lines, for example, the outer seal layer line 5c, does not include a spacer, and the other structures are exactly the same as in the first embodiment. be.

In this example, the seal layer line 5c contains fewer air bubbles that are likely to be trapped during spacer mixing, so that the airtightness of the liquid crystal display panel is further improved. In the above two embodiments, two sealing layer lines are used, but it goes without saying that three or more sealing layer lines may be used to further enhance the effect, if necessary. Furthermore, the sealing layer 5 may be applied by screen printing or the like instead of using a dispenser.

FIG. 3 is a diagram illustrating the detection of air bubbles in a seal layer according to a third embodiment of the present invention, in which FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line XX'. In the figure, 50 is a coloring agent mixed in the seal layer 5, and 150 is a bubble trapped in the seal layer 5.

[0023] As the material for the sealing layer, an ordinary white epoxy resin adhesive is used, into which may be added a pigment or dye other than white, for example, about 5% by weight of an anthraquinone derivative dye. The mixture is mixed, and if necessary, a required amount of spacer is mixed therein and applied to a width of, for example, 0.5 mm using a dispenser, and then dried and cured by heating according to a conventional method.

In this case, air bubbles 150 are present in the sealing layer 5.
Even if the bubbles are trapped, if light is applied from below the substrate as shown in the same figure (b), the effect of the colorant 50 will cause the bubbles to form.
The light (2) that passes through the 50 part has a higher intensity than the light (2) that passes through the other parts, and the seal layer 5 appears colored in an easily distinguishable color, for example, red, and the air bubbles 150
Since the presence of a defective product can be determined extremely easily and reliably, defective products can be eliminated at an early stage of the process, making it possible to reduce man-hours and reduce waste.

[0025] In the above embodiment, the color is red, but the present invention is not limited to this, and it goes without saying that other easily distinguishable colors other than white may be used. The above embodiments are merely examples, and other materials, dimensions, detailed process conditions, etc., or combinations thereof may be selected and used as long as they do not go against the spirit of the present invention. Needless to say.

[0026]

As explained above, according to the present invention, since the seal layer 5 is composed of a plurality of seal layer wires, the width of each seal layer wire can be narrowed, and the width of each seal layer wire can be reduced. Since the solvent can be easily removed, the generation of bubbles is reduced, and by using a plurality of tubes, the probability of airtightness deterioration due to the generation of bubbles can be reduced. Furthermore, although air bubbles are generally often taken in when mixing spacers, such air bubbles do not exist in seal layer wires that do not include spacers, so the composite seal layer wire structure further improves airtightness. Furthermore, by coloring the seal layer 5 in a color other than white, bubbles contained in the seal layer can be easily identified, shortening inspection time and reducing rejects.
This greatly contributes to improving the quality and yield of liquid crystal display devices, as well as lowering prices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a seal layer coating pattern of a first embodiment of the present invention.

FIG. 2 is a diagram showing a seal layer coating pattern according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating bubble detection in a seal layer according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a liquid crystal display panel.

FIG. 5 is a diagram showing an example of a conventional seal layer application pattern and a cross-sectional example of a seal portion.

[Explanation of symbols]

1 is a transparent substrate, 2 is a drive electrode; 3 is an alignment film; 4 is liquid crystal, 5, 5' is a sealing layer, 5a, 5b, 5c are seal layer lines, 50 is a coloring agent, 150 is a bubble,

Claims (3)

[Claims] 1. Two transparent substrates (1) on which at least a driving electrode (2) and an alignment film (3) are laminated are bonded together with a sealing layer (5) in between so as to form a certain gap, A liquid crystal display panel formed by injecting and sealing a liquid crystal (4) into the gap, characterized in that the sealing layer (5) is composed of a plurality of sealing layer lines. 2. The sealing layer (5) consisting of the plurality of sealing layer lines includes a sealing layer (5a) including at least one spacer line and a sealing layer (5) not including at least one spacer.
2. The liquid crystal display panel according to claim 1, wherein the liquid crystal display panel comprises: c) a line. Claim 3: At least a driving electrode (2) and an alignment film (3).
) are laminated and bonded together with a sealing layer (5) in between so that a certain gap is formed, and liquid crystal (4) is injected into the gap and sealed. A liquid crystal display panel characterized in that the sealing layer (5) is colored in a color other than white.