Claims
- 1. A normally white liquid crystal display capable of displaying an image to a viewer, the display comprising:
- a pair of electrodes sandwiching a twisted nematic liquid crsytal layer therebetween, said pair of electrodes for applying a voltage across said liquid crystal layer;
- first and second orientation means disposed on opposite sides of said liquid crystal layer for orienting liquid crystal molecules of said liquid crystal layer, said first orientation means defining a first direction and said second orientation means defining a second direction;
- a positively birefringent uniaxial retardation film disposed on the same side of said liquid crystal layer as said first orientation means, said retardation film being oriented such that its optical axis is in one dimension substantially parallel plus or minus up to about 25.degree. relative to said second direction thereby enabling the display to display to the viewer an image with improved contrast ratios and reduced inversion; and
- wherein said retardation film is oriented relative to said first and second directions so that the display achieves a white light contrast ratio of at least about 10:1 over a horizontal angular span of at least about 100.degree. and over a vertical angular span of greater than about 50.degree. and wherein said retardation film has a retardation value of d.multidot..DELTA.n in the range of from about 100-250 nm where "d" is the thickness of said film and .DELTA.n is its birefringent value.
- 2. The display of claim 1, wherein said film has a retardation value of from about 100-200 nm.
- 3. The display of claim 1, wherein said one dimension is parallel to a planar surface of said retardation film.
RELATED APPLICATIONS
This is a continuation of application Ser. No. 08/255,971, filed Jun. 8, 1994, (to be U.S. Pat. No. 5,576,861) which is a CIP of both 08/235,691, filed Apr. 29, 1994, now U.S. Pat. No. 5,594,568, and 08/167,652, filed Dec. 15, 1993 (U.S. Pat. No. 5,570,214), the disclosures of which are incorporated herein by reference.
US Referenced Citations (42)
Foreign Referenced Citations (2)
Number |
Date |
Country |
55-45037 |
Mar 1980 |
JPX |
3-13916 |
Jan 1991 |
JPX |
Non-Patent Literature Citations (4)
Entry |
"Wide Viewing Angle LCD Using Retardation Films" by Yamagishi et al, Japan Display '89, pp. 316-319. |
"Phase Difference Plate and Liquid Crystal Electro-Optical Device Using this Plate" by Okumura. |
"Liquid Crystal Display Device" by Watanabe. |
"The Symmetry Property of a 90 Degree Twisted Nematic Liquid Crystal Cell" by Lien. |
Related Publications (1)
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Date |
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167652 |
Dec 1993 |
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Continuations (1)
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Number |
Date |
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Parent |
255971 |
Jun 1994 |
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Continuation in Parts (1)
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235691 |
Apr 1994 |
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