JPH02136823A - Liquid crystal optical element - Google Patents

Abstract

PURPOSE:To inexpensively obtain the liquid crystal optical element which is stable in display grade at a high yield with a simplified stage by previously integrating a polarizing plate and a phase difference plate. CONSTITUTION:The linearly polarizing plate 1 and the phase difference plate 2 are lamination-worked and integrated via an epoxy adhesive agent 3. Other adhesive agents besides the above-mentioned adhesive agent are usable as well as the material of the adhesive agent 3 if these materials are uniform in the optical system. Generation of the intrusion of air bubbles and the adhesion of dust, etc., between the polarizing plate 1 and the phase difference plate 2 is obviated. The misregistration of the phase difference plate 2 and the polarizing plate 1 is entirely eliminated and the generation of unequal colors, etc., with respect to the display grade is minimized. The liquid crystal element having the stable quality is obtd. in this way and the improvement in the yield and the reduction of the cost are attained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a neutralized twisted nematic type liquid crystal display device (hereinafter referred to as an NTN percussion liquid crystal display device) which eliminates the coloring of a super twisted nematic type liquid crystal display device. The present invention relates to liquid crystal optical fibers.

[Conventional technology]

The manufacturing method for conventional NTN-type liquid crystal display devices, especially those using a retardation film as an optically anisotropic material, involves pasting a retardation film on one side of the display liquid crystal cell (=J), then attaching a retardation film to both sides of the display liquid crystal cell. A polarizing plate was attached.

[Problem to be solved by the invention]

However, if the retardation film and the polarizing plate are pasted separately as in the conventional technology, air bubbles may enter between the retardation film and the polarizing plate other than between the liquid crystal cell and the retardation film, and dust may adhere, resulting in a reduction in yield. This was the cause of a significant decrease in Further, there were also major problems such as positional deviation and deterioration of display quality due to the accuracy of bonding the retardation film and the polarizing plate.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide, at a low cost, a two-piece liquid crystal optical element that is simpler than the conventional one and has a high yield and stable display quality. .

[Means to solve the problem]

In order to achieve the above object, the liquid crystal optical element of the present invention has the following configuration. That is, at least one of a liquid crystal cell formed by sandwiching a twisted oriented nematic liquid crystal between a pair of electrode substrates disposed opposite to each other, and a pair of polarizing plates disposed on both sides of the liquid crystal cell. In the manufacturing process of a liquid crystal optical element in which a retardation film is provided, the polarizing plate and the retardation film are integrated in advance.

[Effect]

As described above, according to the configuration of the present invention, since the polarizing plate and the retardation film are integrated, the intrusion of air bubbles and the adhesion of dust, etc. do not occur between the polarizing plate and the retardation film. Not only is there no displacement, but there is also no positional shift, making it possible to stably supply liquid crystal display devices with high display quality. It also reduces costs by reducing the number of steps by one.

[Example 1] Hereinafter, the present invention will be specifically described based on an example shown in the drawings.

FIG. 1 is a cross-sectional view of a schematic structure of a retardation film integrated with a polarizing plate showing an embodiment of the present invention. In the figure, 1 is a linear polarizing plate, 2 is a retardation film, and they are laminated and integrated using an epoxy adhesive 3.

The material of the adhesive is not particularly limited, and other adhesives may be used as long as they are optically uniform.

Further, the adhesive may be a pressure-sensitive adhesive.

[Example 2] FIG. 2 is a cross-sectional view of the schematic structure of an NTN liquid crystal display element constructed using the polarizing plate-integrated retardation film in FIG. 1 of Example 1. In the figure, reference numeral 4 denotes a retardation film integrated with a polarizing plate, which is attached to an upper substrate 6 via an acrylic adhesive 5.

A nematic liquid crystal layer 7 is sandwiched between an upper substrate 6 and a lower substrate 9 with an epoxy sealant 8 interposed therebetween. Reference numeral 10 denotes a lower polarizing plate, which is attached to the lower substrate 9 with an acrylic adhesive 5.

FIG. 3 is an explanatory diagram showing the relationship between the respective axes of the liquid crystal display device in the example shown in FIG. 2, and the direction of the molecular axis of the liquid crystal molecules in contact with the substrate is shown as the rubbing direction.

In the figure, R1 and R2 are the rubbing directions of the upper substrate 6 and lower substrate 9 of the liquid crystal cell 11, respectively, and T is the rubbing direction of the liquid crystal cell 11.
1, θ is the angle between the rubbing direction R1 of the upper substrate 6 of the liquid crystal cell 11 and the stretching axis direction F of the retardation film 2, and θ1 is the angle between the rubbing direction R1 of the upper substrate 6 of the liquid crystal cell 11 and the stretching axis direction F of the retardation film 2;
The angle between the stretching axis direction F and the direction P1 of the absorption axis (polarization axis) of the upper polarizing plate 1, and θ2 is the angle between the rubbing direction R2 of the lower substrate 9 and the direction P2 of the absorption axis (polarization axis) of the lower polarizing plate 10. In addition, the conditions for the liquid crystal cell 11 and the polarizing plate-integrated retardation film to obtain a good display are exemplified below.

In FIG. 3, for example, the twist angle T of the liquid crystal molecules of the liquid crystal cell 11 is about 200 degrees, the product Δn-d of the birefringence of the liquid crystal and the cell thickness is about 0°9 μm, and the angle θ is about 90°.
@ If angles θ1 and θ2 are each 45°, then the product Δn·d of the refractive index anisotropy Δn of the retardation film 2 and the film thickness d is 0. 4-0. 6μm
, 0. 7-0.8μm or 0.9-1.1μm
A good display was obtained when

[Example 3] Below, the process of attaching the polarizing plate-integrated retardation film shown in FIG. 2 will be briefly described.

The process for attaching the polarizing plate-integrated retardation film 4 can be carried out in the same manner as the process for attaching the lower polarizing plate 10. Therefore, the two steps of pasting a retardation film and then pasting a polarizing plate as in the prior art can be reduced to one, and the yield can be improved. In addition, regarding display quality, there is a reduction in variation among liquid crystal display elements,
Color unevenness within the same liquid crystal display element can be reduced at the same time.

〔Effect of the invention〕

As described above, according to the configuration of the present invention, since the polarizing plate and the retardation film are integrated, there is no possibility that air bubbles may enter or dust may adhere between the polarizing plate and the retardation film. does not occur. Furthermore, there is no misalignment between the retardation film and the polarizing plate.

Furthermore, regarding the display quality, the occurrence of color unevenness etc. can be minimized and a liquid crystal optical element of stable quality can be provided. Furthermore, since one step can be reduced, yields can be improved and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a polarizing plate-integrated retardation film used in the liquid crystal optical element of the present invention. 1 is a linearly polarizing plate, 2 is a retardation film, and 3 is an epoxy adhesive for bonding the linearly polarizing plate and the retardation film. FIG. 2 is a cross-sectional view of an NTN liquid crystal display element constructed using a polarizing plate-type retardation film in the first embodiment of the present invention. 4... Polarizing plate integrated retardation film 5... Acrylic adhesive 6... Upper glass substrate 7... Liquid crystal layer 8... Seal material 9... Lower glass substrate 10... Lower FIG. 3 is an explanatory diagram showing the relationship between the respective axes of the NTN liquid crystal display device shown in FIG. R1: Rubbing direction of the upper glass substrate 6 R2: Rubbing direction of the lower glass substrate 9 P1: Absorption axis (polarization axis) of the upper polarizing plate 1 P2: Absorption axis (polarization axis) of the lower polarizing plate 10 axis) F...Stretching axis θ of the retardation film 2...Angle θ1 between the rubbing direction R1 of the upper glass substrate 6 and the stretching axis F of the retardation film 2...Absorption axis of the upper polarizing plate 1 ( Angle θ2 between the polarizing axis) Pl and the stretching axis F of the retardation film 2 Angle T between the rubbing direction R2 of the lower glass substrate 9 and the absorption axis (polarizing axis) P2 of the lower polarizing plate 10... Twisting angle and direction of liquid crystal molecules in liquid crystal cell 11

Claims (1)

[Claims] A liquid crystal cell is formed by sandwiching a twisted oriented nematic liquid crystal between a pair of electrode substrates placed opposite each other, and a pair of polarizing plates are placed on both sides of the liquid crystal cell. A liquid crystal optical element provided with a retardation film, characterized in that the polarizing plate and the retardation film are integrated in advance.