Claims
- 1. A method of making and using a normally white twisted nematic liquid crystal display comprising the steps of:
- sandwiching a liquid crystal layer between first and second substrates;
- providing electrodes for selectively applying voltage across the liquid crystal layer in a number of different pixels;
- providing a front orientation or rub film and a rear orientation or rub film on opposite sides of the liquid crystal layer, the rear and front orientation films having orientation or rub directions substantially perpendicular to one another;
- providing a rear polarizer having a transmission axis and a front polarizer or analyzer having a transmission axis on opposite sides of the liquid crystal layer, the rear and front polarizers oriented so as to define a normally white display;
- providing a first negative retardation layer having a retardation value (d.multidot..DELTA.n) of from about 80-200 nm between the liquid crystal layer and one of the polarizers, the first negative retardation layer having an optical axis substantially perpendicular to substantially planar surfaces of the substrates;
- providing a second retardation layer located so that the liquid crystal layer is located between the first and second retardation layers; and
- directing light from a backlight through the rear polarizer so that the liquid crystal display exhibits a white light contrast ratio of at least about 10:1 over a vertical angular span of greater than about 60.degree. and over a horizontal angular span greater than about 100.degree..
- 2. The method of claim 1, further comprising the step of providing the second retardation, layer as a negative retarder with a retardation value of from about 80-200 nm, the second retardation layer having an optical axis substantially perpendicular to the surfaces of the substrates.
- 3. The method of claim 1, further comprising the step of orienting the retardation layers and polarizers relative to one another so that the display exhibits a white light contrast ratio of at least about 10:1 over a horizontal angular span of at least about 120.degree..
- 4. The method of claim 1, wherein d.multidot..DELTA.n of the liquid crystal material is from about 400-550 nm.
- 5. The method of claim 1, wherein the display exhibits a white light contrast ratio of at least about 50:1 over a horizontal angular span of at least about 60.degree. and a vertical angular span of at least about 25.degree..
Parent Case Info
This is a continuation of application Ser. No. 08/167,652, filed Dec. 15, 1993, now U.S. Pat. No. 5,570,214.
US Referenced Citations (13)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0349900 |
Jan 1990 |
EPX |
0367616 |
May 1990 |
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Continuations (1)
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Number |
Date |
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Parent |
167652 |
Dec 1993 |
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