JPS6156326A - Polarizing plate of liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the mechanical strength of a polarizing plate and the reliability at a high temperature and high humidity, and to make a device thin in shape by sticking a pair of films having light transmitting properties so that its drawing axis directions are orthogonal to each other, and polarizing performance is given to one of them. CONSTITUTION:A polarizing plate 1 is constituted by sticking a transparent film 2 and 3 drawn by one axis in the direction as indicated with an arrow A and B by an adhesive agent 4 so that its drawing axis directions are orthogonal to each other. One film 3 is a polarizer, dyed by a dichroic coloring matter, and has polarizing performance by which the drawing axis direction B is a polarized light absorbing axis. In this way, when the film 2 and 3 of the same material quality are stuck to each other, warping or bending caused by thermal contraction are not generated. Also, a luquid crystal display device is constituted by polarizing plates 1a, 1b, and injecting a liquid crystal 6 into a space formed by a spacer 5 interposed between them, and it is set so that films 3a, 3b having polarizing performance face each other, and also the drawing axis serving as a polarized light absorbing axis is orthogonal to the direction B.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a polarizing plate that also serves as a substrate for a liquid crystal display device.

BACKGROUND ART FIG. 7 is a cross-sectional view of a typical prior art liquid crystal display device. A liquid crystal 33 is sealed in a space formed by two substrates 30.31 made of glass plates and a spacer 32 interposed between the substrates 30.31, and a polarizing plate 34.3 is placed on the outer surface of the substrate 30.31. A liquid crystal display device is constructed by arranging 35, respectively. In this way, a liquid crystal display device using a glass plate as the substrate 30, 31 is limited by the mechanical strength of the glass, and cannot respond to the thinning that is currently being pursued.

Furthermore, it has drawbacks such as poor impact resistance and is also inferior in productivity. Therefore, in recent years, liquid crystal display devices using synthetic resin films as substrates have been developed. For example, a liquid crystal display board is constructed by replacing the substrates 30, 31 shown in FIG. 7 with films made of synthetic resin such as polyethylene terephthalate, and replacing the polarizing plates 34, 35 with laminates made of synthetic resin as shown in FIG. FIG. 9 is an exploded perspective view of the laminate of FIG. 8. A film made of polyvinyl alcohol to which iodine, a dichroic dye, is adsorbed is used as a polarizer 36;
A support plate 3 made of a synthetic resin such as acrylic or thoria-7tylcellulose is held between both sides of the support plate 3 with an adhesive 37 interposed therebetween.
8, polarizing plates 34 and 35 are formed. The film of the polarizer 36 is stretched in the direction indicated by arrow F, and the direction F becomes the polarized light absorption axis. Polyvinyl alcohol, which is the material of the polarizer 36, has poor smoothness, moisture resistance, and dimensional stability, so it needs to be protected by the support plate 38.

Problems to be Solved by the Invention Liquid crystal display devices using synthetic resin films as substrates as described above have problems in that they have poor heat resistance and moisture resistance, and are susceptible to shrinkage and warping due to thermal contraction. Furthermore, polarizers made of polyvinyl alcohol have the problem of decolorization or discoloration.

An object of the present invention is to provide a polarizing plate for a liquid crystal display device that does not warp or bend due to heat shrinkage, improves mechanical strength and reliability under high temperature and high humidity, and allows the liquid crystal display device to be made thinner. It is to be.

Means for Solving the Problems The present invention provides at least one pair of translucent films disposed on both sides of the liquid crystal of a liquid crystal display device and stretched in a uniaxial direction so that their stretching axes are orthogonal to each other. This is a polarizing plate for a liquid crystal display device, characterized in that a film attached to a film having one of the stretching axis directions is dyed with a dichroic dye to impart polarizing performance.

According to the present invention, a pair of uniaxially stretched translucent films are pasted so that their stretching axes are perpendicular to each other, and one of the stretching axes is orthogonal to each other. Since the film is dyed with a dichroic dye, the liquid crystal display device can be made thinner without warping or bending due to heat shrinkage.

Embodiment FIG. 1 is a sectional view showing the structure of a polarizing plate 1 of the present invention.
FIG. 2 is an exploded perspective view when the polarizing plate 1 of FIG. 1 is used as a component of a liquid crystal display device. A polarizing plate 1 is constructed by pasting together a transparent film 2 uniaxially stretched in the direction of arrow A and a transparent film 3 uniaxially stretched in the direction of arrow B with an adhesive 4. The films 2 and 3 are laminated so that the stretching axis direction A of the film 2 and the stretching axis B of the film 3 are orthogonal to each other. One film 3 is a polarizer, is dyed with a dichroic dye, and has a polarizing ability in which the stretching axis direction B is the polarized light absorption axis. The material of the film 3 is a synthetic resin, such as polyethylene terephthalate (PET), which has excellent abrasion resistance, heat resistance, dichroic dye stainability, and impact resistance, and its thickness is preferably about 60 μm. be. Since the film 3 is used as a polarizer, it is uniaxially stretched, and since the heat shrinkage rate is different between the axial direction B and the direction perpendicular to the axial direction B, the film 3 alone may warp or bend due to heat shrinkage. Therefore, if the film 2 made of the same material as the film 3, for example, PET, and which has been stretched along the -axis, is bonded together as described above, warping or bending due to heat shrinkage will not occur. For this purpose, it is preferable that the thickness of the film 2 be approximately the same as the thickness of the film 3.

FIG. 3 is a sectional view of an embodiment of a liquid crystal display device in which the polarizing plate 1 of the present invention is arranged as shown in FIG. The liquid crystal display device is constructed by sealing a liquid crystal 6 in a space formed by a spacer 5 interposed between two polarizing plates 1a and 1b. The polarizing plate 1 is set so that the films 3a and 3b having polarization ability face each other, and the stretching axis direction B, which is the polarized light absorption axis, is orthogonal to each other. In a conventional liquid crystal display device in which a substrate and a polarizing plate are arranged separately, the thickness is limited to about 1 mm, whereas in a liquid crystal display device like the one shown in Figure 3, the thickness is limited to 300 μm.
It is also possible to make it less than m.

FIG. 4 is a diagram showing the manufacturing process of the polarizing plate 1.

Film 2.3 is wound into a roll as shown;
After applying adhesive to the adhesive surface, it is subjected to pressure and heat treatment. Therefore, continuous molding of the polarizing plate 1 is possible,
Workability in the manufacturing process is improved.

FIG. 5 is a sectional view showing another embodiment of the polarizing plate 1 of the present invention, and FIG. 6 is an exploded perspective view thereof.

A polyethylene terephthalate film 9 whose stretching axis direction E is perpendicular to each other is sandwiched between polyethylene terephthalate films 7 and 8 whose stretching axis directions are the same as shown by arrows C and D, and pasted with an adhesive 10. Thus, the polarizing plate 1 is formed. The film 9 is dyed with a dichroic dye and is made into a polarizer having polarizing ability.

Effects As described above, according to the present invention, warping or bending due to thermal contraction does not occur, mechanical strength and reliability at high temperature and high humidity are improved, and it is possible to easily realize a thinner liquid crystal display device. Furthermore, productivity can also be improved compared to conventional techniques.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the polarizing plate 1 of the present invention, and FIG. 2 is a sectional view of the polarizing plate 1 of the present invention.
FIG. 3 is a sectional view of a liquid crystal display device including the polarizing plate 1 of the present invention as a component, FIG. 4 is a perspective view showing the manufacturing process of the polarizing plate 1, and 'f4S' 6 is an exploded perspective view of the embodiment shown in FIG. 5, FIG. 7 is a sectional view of a liquid crystal display device in the prior art, and FIG. The cross-sectional view of the plate, FIG. 9, is a perspective view of the polarizing plate shown in FIG. 1... Polarizing plate, 2, 3... Film, A-E...
Extension Axis Agent Patent Attorney Kei Nishi Part 2 Figure 311 @51!1 6rIII

Claims (1)

[Scope of Claims] In a polarizing plate disposed on both sides of a liquid crystal of a liquid crystal display device, at least a pair of translucent films stretched in a uniaxial direction are pasted so that their stretching axes are orthogonal to each other. 1. A polarizing plate for a liquid crystal display device, characterized in that a film having one of the stretching axis directions is dyed with a dichroic dye to impart polarizing performance.