JPH11133395A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the stresses from polarizing plates against warpage and distortion and to relieve a change with lapse of time by providing both outer sides of a liquid crystal cell with the polarizing plates and making flexible films present between the polarizing plates and the substrates of the liquid crystal cell. SOLUTION: Both outer sides of the liquid crystal cell are provided with the polarizing plates 7, 8 and the flexible films 5, 6 are made present between the polarizing plates 7, 8 and the substrates of the liquid crystal cell. Further, the flexible film 5, 6 are obtd. by forming a tacky adhesive layer 9 by using a tacky adhesive and are preferably laminated and integrated with the substrates 1 of the liquid crystal cell and the polarizing plates 7, 8. The flexible films are provided with such tacky adhesive layer 9, by which the additional relieving of the warpage and the distortion is made possible. Films of polyethylene terephthalate, polycarbonate, etc., having high transparency and decreased dimensional fluctuations are used as the flexible films 5, 6. The tacky adhesive layer 9 is preferably an acrylic system and the tacky adhesive layer 9 between the flexible films 5, 6 and the polarizing plates 7, 8 is preferably a polyester system, polyacrylic system, etc.

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 comprising a liquid crystal cell having a liquid crystal sandwiched between a pair of flexible polymer film substrates and at least a polarizing plate outside the substrate of the liquid crystal cell. Related to the element.

[0002]

2. Description of the Related Art A liquid crystal display device having a liquid crystal cell using a flexible polymer film substrate (hereinafter also referred to as a PF-LCD) is thinner and lighter in weight than a liquid crystal display device formed of a glass substrate. It has the advantage of having flexibility such as being easily bent. The liquid crystal display device using the flexible polymer film substrate has the above advantages, but these points are liable to receive external force and stress, and therefore, the liquid crystal display device panel is warped and has a large thickness. However, there is a disadvantage that unevenness of color or unevenness of color of a panel is apt to occur.

Techniques for improving the disadvantages of the PF-LCD include, for example, JP-A-6-67172 and JP-A-8-67172.
-54620. In these inventions, a plastic film is provided as a reinforcing plate on the outermost layer of the panel in order to reduce warpage caused by changes in temperature and humidity of the panel,
This reinforcing plate reduces the warpage of the liquid crystal display element itself.

[0004]

SUMMARY OF THE INVENTION A liquid crystal cell having a liquid crystal sandwiched between a pair of flexible polymer film substrates and a liquid crystal display device having at least a polarizing plate outside the substrate of the liquid crystal cell. Examples of the polarizing plate include a transmission type polarization film and a reflection type polarization film provided with a semi-transmissive reflection layer or a reflection layer. For example, in the case of an STN mode liquid crystal display device, a combination of a retardation plate and the above-mentioned transmission type polarizing film is used.

[0005] The polarizing plate is composed of a polarizer and a protective layer thereof. As the protective layer, a triacetate cellulose (hereinafter, referred to as TAC) film is generally used. Usually, a polarizer is used in which iodine or a dye is adsorbed on a polymer base material such as polyvinyl alcohol and stretched and fixed in a certain direction. The polarizing plate is, for example, 20 μm
When a polarizer having a thickness of 50 to 190 μm is sandwiched between both sides of a TAC film, the thickness is 120 to 4 μm.
00 μm (excluding the thickness of the pressure-sensitive adhesive layer and the reflective layer). Since the polarizing plate has the above-described structure, the polarizing plate has a stress at the time of manufacturing, and the stress warps due to a change with time and has an effect as distortion. Furthermore, since the materials used for the polymer film substrate and the polarizing plate and the thermal history are usually different, the balance of the stress is lost, and warpage and distortion are generated. The present invention relates to a liquid crystal cell having a liquid crystal sandwiched between a pair of flexible polymer film substrates and a liquid crystal display device having at least a polarizing plate outside the substrate of the liquid crystal cell, wherein An object of the present invention is to provide a PF-LCD in which a problem is improved, a stress from a polarizing plate against warpage and distortion is reduced, and a change with time is reduced.

[0006]

SUMMARY OF THE INVENTION One of the features of the present invention is as follows.
In a liquid crystal cell having a liquid crystal sandwiched between a pair of flexible polymer film substrates and a liquid crystal display device having at least a polarizing plate outside a substrate of the liquid crystal cell, one or both sides of the liquid crystal cell outside. By providing a polarizing plate on the substrate and providing a flexible film between the polarizing plate and the substrate of the liquid crystal cell, it was possible to provide a liquid crystal display device which solved the above-mentioned problems. Further, it is more preferable that the flexible film is formed by forming an adhesive layer using an adhesive and by laminating and integrating the liquid crystal cell substrate and the polarizing plate. By providing such an adhesive layer, the warpage, distortion, and the like can be further reduced.

Hereinafter, the structure of one example of the liquid crystal display device of the present invention will be described with reference to FIG. In FIG. 1, 1 is a polymer film substrate of a liquid crystal cell, 2 is a sealing material formed around the substrate 1, 3 is a liquid crystal sealed between the substrates 1 via a gap material 4, and 5 and 6 are acceptable. Flexible film, 7, 8
Is a polarizing plate. In addition, the substrate 1 and the flexible films 5 and 6
, And between the flexible films 5 and 6 and the polarizing plates 7 and 8, an adhesive layer 9 exists. Therefore, the flexible films 5 and 6 have a structure in which the flexible films 5 and 6 are laminated and integrated with the adhesive layer 9 interposed therebetween.

FIG. 2 shows another example of the structure of the liquid crystal display device of the present invention. 2 differs from that of FIG. 1 in that a flexible film 5 is provided only on one side of the liquid crystal cell.

As the flexible films 5 and 6, films having high transparency and small dimensional variations are used, and specific examples thereof include polyethylene terephthalate, polycarbonate, polyether sulfone, polyarylate and the like. Usually, a thickness of 50 to 200 μm is preferable. The flexible films 5 and 6 may be coated with a gas barrier material or a hard coat material.

The pressure-sensitive adhesive layer 9 is made of an acrylic material having optical transparency and adhesive strength, and a pressure-sensitive adhesive layer 9 for forming the pressure-sensitive adhesive layer 9 between the flexible films 5, 6 and the polarizing plates 7, 8. As the agent, polyester-based, polyacryl-based, epoxy-based, and polyurethane-based agents are preferable. The thickness of the pressure-sensitive adhesive layer 9 is usually preferably 20 to 100 μm.
The thickness of the pressure-sensitive adhesive layer 9 for adhering each of the pair of flexible films 5 and 6 may be the same or different. In particular, by providing a thickness between the flexible films 5 and 6 It is also possible to balance the stress by the difference in the thickness, but also in this case, the thickness within the above range is preferable.

As the polarizing plate, those commonly used in liquid crystal display devices are used, but the type may or may not include a retardation plate. As for the reflective polarizing film, either a reflective type or a transflective type can be used.

[0012]

Embodiments of the present invention will be described below.

Example 1 A polycarbonate film (thickness: 120 μm) coated with a gas barrier layer and a solvent-resistant layer was used as a substrate.
The one on which a TO electrode was formed was used. Using this substrate, a liquid crystal display cell having an outer shape of 30 mm × 60 mm was produced. The configuration of this liquid crystal cell is as shown in FIG. PES having a thickness of 50 μm as a flexible film was adhered to a polarizing plate on the above cell to produce a liquid crystal display device. The pressure-sensitive adhesive layer is formed with a thickness of 30 μm on both sides of the flexible film. The above liquid crystal display element is reliable for 240 hours under high temperature and high humidity (40 ° C., 90% RH), high temperature (60 ° C.), low temperature (−20 ° C.) environment and 10 cycles under temperature cycle (65 ° C. to -10 ° C.) environment. A sex test was performed. As a result, no warpage-distortion was observed in the liquid crystal display element under any environment, and good results were obtained.

Example 2 A substrate similar to that of Example 1 was used. Using this substrate, a liquid crystal display cell having an outer shape of 30 mm × 60 mm was produced. The configuration of the liquid crystal display device is as shown in FIG.
A flexible film is provided only on one side of the liquid crystal cell, and the flexible film is PES having a thickness of 50 μm. The pressure-sensitive adhesive layer is formed with a thickness of 30 μm on both sides of the liquid crystal cell. The above liquid crystal display element is reliable for 240 hours under high temperature and high humidity (40 ° C., 90% RH), high temperature (60 ° C.) and low temperature (−20 ° C.) environment and 10 cycles under temperature cycle (65 ° C. to -10 ° C.) environment. A sex test was performed. As a result, no warpage-distortion was observed in the liquid crystal display element under any environment, and good results were obtained.

Example 3 A substrate similar to that of Example 1 was used. Using this substrate, a liquid crystal display cell having an outer shape of 30 mm × 60 mm was produced. The configuration of this liquid crystal cell is as shown in FIG.
At this time, the thickness of the adhesive layer is 50 μm between the flexible film and the polarizing plate, and 30 μm between the flexible film and the liquid crystal cell.
m. The above-mentioned liquid crystal display element was subjected to high temperature and high humidity
% RH), a high temperature (60 ° C.), and a low temperature (−20 ° C.) environment for 240 hours and a temperature cycle (65 ° C. to −10 ° C.) 10-cycle reliability test. As a result, under any environment, the liquid crystal display element was not warped or distorted, and good results were obtained.

[0016]

According to the present invention, the stress caused by the aging of the polarizing plate or the change in temperature and humidity can be alleviated. Therefore, the warpage and distortion of the liquid crystal display element itself can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a liquid crystal display device of the present invention.

FIG. 2 is a schematic sectional view of another example of the liquid crystal display device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 polymer film substrate 2 sealing material 3 liquid crystal 4 gap material 5 flexible film 6 flexible film 7 polarizing plate 8 polarizing plate 9 adhesive layer

Claims (5)

[Claims] 1. A liquid crystal cell having a liquid crystal sandwiched between a pair of flexible polymer film substrates and a liquid crystal display element comprising at least a polarizing plate outside a substrate of the liquid crystal cell, wherein the liquid crystal cell is A liquid crystal display device comprising: a polarizing plate provided on one or both sides of the outer surface of the liquid crystal panel; and a flexible film between the polarizing plate and the substrate of the liquid crystal cell. 2. The liquid crystal display device according to claim 1, wherein the flexible film is present between the polarizing plate and the substrate of the liquid crystal cell via an adhesive layer. 3. The liquid crystal display device according to claim 1, wherein the thickness of the flexible film is 50 mm or more. 4. The liquid crystal display device according to claim 2, wherein the pressure-sensitive adhesive layer has a thickness of 20 mm or more. 5. The liquid crystal display element according to claim 2, wherein the thickness of the pressure-sensitive adhesive layer is different on both sides of the liquid crystal cell.