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Wide viewing angle polarizer and liquid-crystal display device

Inactive Publication Date: 2010-09-14
NITTO DENKO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]An object of the invention is to provide a phase retarder-containing polarizer which is excellent in reduction in thickness and which can be used for forming a liquid-crystal display device such as a VA liquid-crystal display device improved in viewing angle characteristic and high in contrast.
[0010]According to the invention, the retardation layer B is excellent in reduction in thickness because it is made of a liquid-crystal coating film. Moreover, because the retardation layer B is supported by the retardation layer A, a high-quality composite phase retarder excellent in reduction in thickness can be obtained. Moreover, because the composite phase retarder is bonded to a polarizing film so as to serve as a transparent protective layer, a separate transparent protective layer to be bonded to the polarizing film can be omitted. Hence, greater reduction in thickness can be achieved. When the combination of the composite phase retarder and the polarizing film is used, the viewing angle of the liquid-crystal cell can be improved extremely.

Problems solved by technology

Use of the former phase retarder, however, brings about a problem that the volume of the phase retarder is large because of use of two retardation films.
There arises still the problem that the volume of the phase retarder is large.

Method used

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  • Wide viewing angle polarizer and liquid-crystal display device
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Examples

Experimental program
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Effect test

example 1

[0040]A polyester film (PET) was vertically stretched through a heating roll to thereby obtain a retardation layer A having Re of 40 nm, Rth of 41 nm and a thickness of 60 μm.

[0041]On the other hand, a nematic liquid-crystal compound represented by the aforementioned formula and a chiral agent represented by the following formula were mixed with each other to set a selective reflection wavelength to be in a range of from 290 to 310 nm. A cholesteric liquid-crystal solution obtained by adding a photo-polymerization initiator to the mixture was applied on a biaxially stretched PET film, heated at 80° C. for 3 minutes and then crosslinked by irradiation with ultraviolet rays to thereby obtain a retardation layer B having a thickness of 1.9 μm, Re of 2 nm and Rth of 132 nm. The retardation layer B was laminated on the retardation layer A through an acrylic-based pressure sensitive adhesive layer having a thickness of 15 μm. The biaxially stretched PET film was separated to thereby obta...

example 2

[0043]A wide viewing angle polarizer was obtained in the same manner as in Example 1 except that the composite phase retarder with the retardation layers A and B inverted to each other in location was disposed so that the retardation layer B faced inward.

example 3

[0044]A composite phase retarder having Re of 41 nm and Rth of 173 nm and a wide viewing angle polarizer having a total thickness of 231 μm were obtained in the same manner as in Example 1 except that the retardation layer A was made of a norbornene resin film laterally stretched by a tenter and having Re of 40 nm, Rth of 102 nm and a thickness of 85 μm whereas the retardation layer B was formed to have a thickness of 1.0 μm, Re of 1 nm and Rth of 71 nm.

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PUM

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Abstract

A wide viewing angle polarizer having: a polarizing film; and a phase retarder adhesively laminated on at least one surface of the polarizing film through an adhesive layer, the phase retarder being made of a composite phase retarder constituted by a laminate in which a retardation layer B of a cholesteric liquid crystal-oriented solidified layer in a selective reflection wavelength range of not larger than 350 nm is supported by a retardation layer A of a thermoplastic resin exhibiting positive birefringence, the composite phase retarder being formed so that the laminate has Re of not smaller than 10 nm and Rth−Re of not smaller than 50 nm when Re and Rth are defined as Re=(nx−ny)X d and Rth=(nx−nz)X d respectively in which nx and ny are in-plane main refractive indices, nz is a thicknesswise refractive index, and d is a layer thickness. A liquid-crystal display device having: a liquid-crystal cell; and a wide viewing angle polarizer defined above and disposed on at least one surface of the liquid-crystal cell.

Description

[0001]The present application is based on Japanese Patent Application No. 2001-312162, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a wide viewing angle polarizer adapted for improvement in viewing angle characteristic of a liquid-crystal display device such as a vertical aligned (VA) liquid-crystal display device.[0004]2. Description of the Related Art[0005]To form a liquid-crystal display device exhibiting excellent display quality in all azimuths by compensation for birefringence of a liquid-crystal cell achieving display through a polarizer, the polarizer needs to be combined with a phase retarder in which main refractive indices nx, ny and nz in three directions, that is, two in-plane directions x and y in association an obliquely viewing direction and one normal direction z, are controlled. Particularly in a VA or OCB liquid-crystal display device, the polarizer needs to be combined w...

Claims

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Application Information

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IPC IPC(8): G02F1/1335G02B5/30G02F1/13363
CPCG02B5/3041G02F1/133528G02F1/133634G02F2201/38G02F2202/28G02F2202/40G02F2413/12G02F1/133635G02F1/1335
Inventor SASAKI, SHINICHIYAMAOKA, TAKASHIMURAKAMI, NAOYOSHIMI, HIROYUKI
Owner NITTO DENKO CORP
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