JPH08320485A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To provide a liquid crystal display device having stable display quality which does not deteriorate by discoloring or decoloring of a polarizing plate even in high temp. and high humidity environment by covering the peripheral part of a polarizing plate adhered to at least one transparent substrate of two transparent substrates with a sealing material. CONSTITUTION: The liquid crystal panel 1 consists of a liquid crystal cell 2 and first and second polarizing plates 3, 4. The liquid crystal cell 2 has a liquid crystal layer 5 and a pair of glass substrate 6, 7 which hold the liquid crystal layer 5 and is disposed between the polarizing plates 3, 4. A sealing material 8, 9 is applied to cover the peripheral part of the side faces 13, 14 of the polarizing plates 3, 4 and the peripheral part of the laminated faces of the glass substrates 6, 7 and the polarizing plates 3, 4. Thereby, the whole side faces of the polarizing plates 3, 4 are not exposed to air so that the polarizing plates are hardly modified by moisture absorption. Further, such a problem that the polarizing plates are partially peeled from glass substrates owing to intrusion of water or the like through the peripheral part of laminating faces between the polarizing plates and the glass substrates can be avoided. Thus, the life of the polarizing plate, and as a result, the life of the whole liquid crystal display device can be prolonged.

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.

[0002]

2. Description of the Related Art Generally, a liquid crystal panel constituting a liquid crystal display device is formed by the following procedure. First, a pair of transparent substrates each having a transparent electrode pattern formed on one side and an alignment film formed thereon are attached to each other with the surfaces of the transparent electrodes facing each other, and liquid crystal is sealed between the pair of transparent substrates. Let it be a cell. Next, a liquid crystal panel is formed by sticking a polarizing plate on one surface of the liquid crystal cell and a polarizing reflection plate or a polarizing plate on the other surface so as to be in close contact with each other. The liquid crystal panel is shown, for example, as shown in FIG. In FIG. 4, 21 and 22 are a pair of transparent substrates, 23 is a liquid crystal layer, and 24
Is a liquid crystal cell composed of transparent substrates 21, 22 and a liquid crystal layer 23, 25 is an upper polarizing plate, 26 is a lower polarizing plate,
27 and 28 are adhesives. It is necessary that the polarizing plates 25 and 26 and the liquid crystal cell 24 maintain a constant distance (including close contact) over the entire display portion. That is, when the polarizing plates 25 and 26 are partially adhered to or separated from the liquid crystal cell 24, interference fringes appear on the display surface of the liquid crystal panel and the display quality is significantly deteriorated. For this reason, normally, the polarizing plates 25 and 26 are adhered with adhesives 27 and 28 over the entire surfaces of the transparent substrates 21 and 22 of the liquid crystal cell 24.

[0003]

In such a conventional liquid crystal display device, the transparent substrate is formed of a glass substrate or a plastic film. For example, in the method of adhering the glass substrate and the polarizing plate with an adhesive,
Applying a polarizing plate having a laminated structure in which a protective layer of a cellulose-based film, for example, a cellulose triacetate film, is coated on both surfaces of a polyvinyl alcohol film or the like having a polarizing property to a liquid crystal cell surface made of a glass substrate to form a liquid crystal display plate. The application to the liquid crystal cell surface is usually performed by bringing the adhesive layer provided on the surface of the polarizing plate into contact with the cell surface and pressing it. However, as the above-mentioned adhesive, those made of an acrylic resin are often used due to its excellent adhesiveness, transparency, etc., but when used in a high temperature and high humidity environment, such as foaming or peeling of the adhesive, etc. This causes problems such as appearance defects. That is,
Even though the entire surface of the polarizing plate is adhered to the glass substrate with an adhesive, water enters inside the bonding surface between the polarizing plate and the glass substrate from the periphery of the mating surface between the polarizing plate and the glass substrate. , Not enough airtightness. As a result, in high temperature and high humidity, there is a drawback that a part of the polarizing plate is peeled off from the glass substrate and interference fringes appear on the display surface of the liquid crystal panel due to water entering between the polarizing plate and the glass substrate. there were. Further, since the polarizing plate has a laminated structure as described above, there is a possibility that moisture may enter between the layers of the polarizing plate from the exposed side surface of the polarizing plate and the polarizing plate may be discolored or faded to be deteriorated. Particularly in the case of a liquid crystal display device used for instrumental display of automobiles and the like, the polarizing plate is required to have severe moisture resistance and heat resistance, and such a defect remarkably impairs the reliability of the entire liquid crystal display device. The present invention is to solve the above problems, even under a high temperature and high humidity environment, the deterioration of the polarizing plate due to discoloration, fading, etc. does not occur, and interference fringes do not appear on the display surface of the liquid crystal panel. An object of the present invention is to provide a stable liquid crystal display device.

[0004]

Means for Solving the Problems The present invention provides a liquid crystal display device including a liquid crystal cell in which a liquid crystal material is filled between two transparent substrates, and is adhered to at least one transparent substrate of the two transparent substrates. The peripheral portion of the polarizing plate to be formed is covered with a sealing material.

[0005]

Since the peripheral portion of the polarizing plate attached to the glass substrate is covered with the sealing material, the entire side surface of the polarizing plate is not exposed and the polarizing plate is likely to deteriorate due to moisture absorption. In addition, a part of the polarizing plate is not peeled off from the glass substrate due to water or the like that has entered from between the periphery of the mating surface of the polarizing plate and the glass substrate, and the life of the polarizing plate, and by extension, the liquid crystal display device as a whole. Longer life.

[0006]

The present invention will be described below with reference to the drawings.
1 and 2 are views showing an embodiment of a liquid crystal display device according to the present invention, and FIG. 1 is a partial plan view of the liquid crystal display device. FIG. 2 is a sectional view taken along the section line AB of FIG.
First, the configuration will be described. In FIGS. 1 and 2, reference numeral 1 is a liquid crystal panel, and the liquid crystal panel 1 is composed of a liquid crystal cell 2 and first and second polarizing plates 3 and 4. The liquid crystal cell 2 includes a liquid crystal layer 5 and a pair of glass substrates 6 and 7 that sandwich the liquid crystal layer 5.
And is sandwiched between the first and second polarizing plates 3 and 4. Further, 8 and 9 represent sealing materials, and the polarizing plates 3 and 4
Are provided in the peripheral portions of the polarizing plates 3 and 4 so as to cover the entire side surfaces 13 and 14 and the periphery of the bonding surface between the glass substrates 6 and 7 and the polarizing plates 3 and 4. In addition, in FIG.
Reference numeral 0 is an electrode terminal, and 11 is a filling port for filling the liquid crystal cell 2 with a liquid crystal material. Further, in FIG. 2, reference numeral 12 is an adhesive for adhering the glass substrates 6 and 7 and the polarizing plates 3 and 4. As the adhesive in this case, an adhesive made of an acrylic resin is used because of its excellent adhesiveness and transparency.
The polarizing plates 3 and 4 are attached to the inner surfaces of the glass substrates 6 and 7 each having a sufficient space for forming the sealing materials 8 and 9 on the surfaces thereof. The liquid crystal panel 1 is the portion other than the portions covered with the sealing materials 8 and 9.
Is the effective display area of. The sealing materials 8 and 9 are
The polarizing plates 3 and 4 are provided so as to cover the entire side surfaces 13 and 14 so that the side surfaces 13 and 14 are exposed and do not come into direct contact with the outside air, and the liquid crystal panel 1 does not become too thick. ing. In this case, as the material of the sealing material, a thermosetting epoxy resin is desirable in the case of thermocompression molding, but unless the polarizing plates 3 and 4 are changed in quality, for example, UV curing is performed by irradiating with ultraviolet rays to cure. Epoxy resin or the like can also be used. In addition, the polarizing plate 3,
No. 4 is a polarizer made by dyeing polyvinyl alcohol with iodine or a dichroic dye and uniaxially stretching it, and is adhered to both sides of the polarizer with adhesive to reinforce or protect the polarizer. It consists of a support. An ordinary cellulose triacetate (TAC) film is used as this support, and its thickness is about 20 to 150 μm. Since the side surfaces 13 and 14 of the polarizing plates 3 and 4 are directly exposed and are not exposed to the outside air, moisture or the like may enter between the polarizing plates 3 and 4 and the glass substrates 6 and 7, and Part of 3 and 4 is peeled off from the glass substrates 6 and 7 respectively, or moisture is absorbed from the side surfaces 13 and 14, so that the iodine dye in the polarizing plates 3 and 4 is exposed to the moisture. It does not melt and escape, and the polarizing plates 3 and 4 do not deteriorate, such as discoloration and fading, and the effective display areas of the polarizing plates 3 and 4 are deteriorated and difficult, and the display characteristics of the liquid crystal panel 1 are stabilized. Next, a method of manufacturing the liquid crystal display device according to this embodiment will be described. FIG. 3 is an explanatory view showing the manufacturing process of the liquid crystal display device according to the above-mentioned embodiment. First, as shown in FIG. 3A, a pair of glass substrates 6 and 7 each having a transparent electrode pattern formed of an ITO film or the like on one surface of a glass substrate and an alignment film formed thereon are provided. Then, epoxy resin or the like is printed on the opposite surfaces of the transparent electrode pattern around the entire periphery except for the liquid crystal filling port to form an adhesive layer 12, and then a spacer is sandwiched between the glass substrates 6 and 7. Then, the upper and lower electrode films are aligned so that they are aligned with each other, and then the glass substrates 6 and 7 are attached to each other. Next, the bonded glass substrates 6 and 7 are placed in a vacuum chamber, the distance between the glass substrates is set to a vacuum, and a liquid crystal material is injected to form a liquid crystal layer 5, and then the injection port is sealed with a sealing material. Thus, the liquid crystal cell 2 is obtained. Next, as shown in FIG. 3B, a polarizing plate 3 is formed on the surface of one glass substrate 6 of the liquid crystal cell 2, and a polarizing plate (or a polarizing reflection plate) 4 is formed on the surface of the other glass substrate 7.
The liquid crystal panel 1 is formed by applying the two so as to be in close contact with each other and adhering them with an adhesive. Polarizing plate 3 and polarizing plate 4
The area of each of the glass substrate 6 and the glass substrate 7 is
The area is smaller than the respective areas, and the margins for forming the sealing materials 8 and 9 on the surfaces of the glass substrate 6 and the glass substrate 7 are set to some extent. The adhesive used for bonding the polarizing plate 3 and the polarizing plate 4 may be the same as the adhesive stuck to the glass substrates 6 and 7. Then, as shown in FIG. 3C, the peripheral portions of the polarizing plates 3 and 4 are evenly covered with the sealing materials 8 and 9, and the polarizing plates 3,
The surface of each of the four side surfaces 13 and 14 of 4 is not exposed. As a method of uniformly covering the peripheral portions of the polarizing plates 3 and 4 with the sealing materials 8 and 9, it is desirable for mass production to apply a sheet-shaped thermosetting epoxy resin to the peripheral portions of the polarizing plates 3 and 4, respectively. However, the method is not limited to this, and may be a method in which a paste-like thermosetting epoxy resin is applied to the peripheral portions of the polarizing plates 3 and 4 and cured. Finally, Figure 3
(D) is explanatory drawing at the time of thermocompression-molding the said sealing material 8. The sealing material 8 covering the peripheral portion including the side surface 13 of the polarizing plate 3 attached to the surface of the glass substrate 6 is pressed by the thermocompression bonding press 15. The thickness of the sealing material 8 covering the polarizing plate 3 is about 50 μm to 300 μm, particularly 100 μm to 20 μm.
0 μm is preferable, and the width of the overlapping portion of the sealing material 8 with the polarizing plate 3 and the glass substrate 6 is preferably 0.5 mm to 1.0 mm. The thickness or width is desirable and sufficient to prevent water vapor and the like from entering the inside of the polarizing plate 3 from the inside.
The temperature for pressing with a thermocompression bonding is 60 ° C to 120 ° C, particularly preferably 80 ° C to 100 ° C, and the thermocompression bonding time is about several seconds (within 10 seconds) to reduce the influence of heat on the polarizing plate 3. It has been empirically confirmed that it is preferable to keep it. The sealing material 9 that covers the peripheral portion of the polarizing plate 4 and the side surface 14 of the polarizing plate 4 attached to the surface of the glass substrate 7 is also thermocompression-bonded and molded in the same manner as above.

[0007]

EFFECTS OF THE INVENTION Even under the use conditions of high temperature and high humidity, it is possible to prevent water vapor and the like from entering the inside of the polarizing plate from the bonding surface between the transparent substrate of the liquid crystal cell and the polarizing plate and the side surface of the polarizing plate. It is possible to provide a liquid crystal display device in which discoloration, discoloration, and deterioration of the plate do not occur, and a part of the polarizing plate is not peeled off from the transparent substrate and display quality is stable and excellent in durability.

[Brief description of drawings]

FIG. 1 is a partial plan view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a manufacturing process of a liquid crystal display device according to an embodiment of the present invention.

FIG. 4 is a schematic front view of a conventional liquid crystal panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Liquid crystal cell 3,4 Polarizing plate 5 Liquid crystal layer 6,7 Glass substrate 8,9 Sealing agent 10 Electrode terminal 11 Filling port 12 Adhesive 13,14 Polarizing plate side surface 15 Thermocompression press

Claims (1)

[Claims] 1. A liquid crystal display device comprising a liquid crystal cell in which a liquid crystal material is filled between two transparent substrates, wherein a peripheral portion of a polarizing plate adhered to at least one transparent substrate of the two transparent substrates is A liquid crystal display device characterized by being covered with a sealing material.