Claims
- 1. A normally white twisted nematic liquid crystal display comprising:
- a liquid crystal layer for twisting at least one normally incident visible wavelength of light from about 80.degree. to 100.degree. as it passes therethrough when said liquid crystal layer is in substantially the "off-state" thereby defining a twisted nematic display;
- a pair of negative biaxial retarders sandwiching said liquid crystal layer therebetween, wherein n.sub.x >n.sub.y >n.sub.z for each of said negative biaxial retarders;
- a pair of positive retarders sandwiching both said liquid crystal layer and said negative biaxial retarders therebetween; and
- wherein retardation value d.multidot.(n.sub.x -n.sub.z) of each of said negative biaxial retarders is from about 70 to 130 nm, retardation value d.multidot.(n.sub.x-n.sub.y) of each of the negative biaxial retarders is from about 3 to 20 nm, and the retardation value of each of said positive retarders is from about 70 to 200 nm.
- 2. The display of claim 1, wherein each of said positive retarders is uniaxial and the retardation value of each of said positive retarders is from about 120 to 160 nm.
- 3. The display of claim 1, wherein the thickness of said liquid crystal layer is from about 4.8 to 6.0 .mu.m and the .delta.n of said liquid crystal is from about 0.075 to 0.095 at room temperature, and wherein the display outputs contrast ratios to the viewer of at least about 30:1 or 30 at horizontal angles along the 0.degree. vertical axis of about .+-.60.degree. when a driving voltage of from about 5.0 to 6.0 volts is applied to said liquid crystal layer.
- 4. The display of claim 3, wherein said display outputs contrast ratios of at least about 30:1 or 30 at vertical viewing angles along the 0.degree. horizontal viewing axis between and including about -7.degree. and +40.degree., when about 5.0 to 6.0 driving volts are applied.
- 5. The display of claim 1, wherein the n.sub.x index direction of one of said negative biaxial retarders is oriented from about 80.degree.-100.degree. relative to the n.sub.x index direction of the other of said negative biaxial retarders.
- 6. A normally white twisted nematic liquid crystal display comprising:
- a liquid crystal layer for twisting at least one normally incident visible wavelength of light from about 80.degree. to 100.degree. as it passes therethrough when said liquid crystal layer is in substantially the "off-state" thereby defining a twisted nematic display;
- a pair of negative biaxial retarders sandwiching said liquid crystal layer therebetween, wherein n.sub.x >n.sub.y >n.sub.z for each of said negative biaxial retarders;
- a pair of positive retarders sandwiching said liquid crystal layer therebetween; and
- wherein the ratio of the positive retardation value d.multidot..delta.n of the positive retarder to the retardation value d.multidot.(n.sub.x -n.sub.z) of the negative biaxial retarder on at least one side of said liquid crystal layer is from about 1:1 to 2:1.
- 7. The display of claim 6, wherein the retardation value d.multidot.(n.sub.x -n.sub.z) of each of said negative biaxial retarders is from about 100 to 200 nm and the retardation value d.multidot..delta.n of each of said positive retarders is from about 80 to 200 nm.
- 8. A method of making a twisted nematic liquid crystal display comprising the steps of:
- providing a pair of biaxial negative retarders defined by n.sub.x >n.sub.y >n.sub.z ;
- providing a pair of positive uniaxial retarders;
- disposing a twisted nematic liquid crystal layer between said pair of negative biaxial retarders, and between said pair of positive retarders; and
- disposing said pair of negative biaxial retarders between said pair of positive retarders so that the resulting display outputs contrast ratios of at least about 30:1 or 30 at horizontal viewing angles along the 0.degree. vertical viewing axis of about .+-.50.degree..
- 9. The method of claim 8, further comprising the step of providing retardation values for said retarders so that the display outputs contrast ratios of at least about 80:1 or 80 along the 0.degree. vertical viewing axis at horizontal viewing angles of about .+-.30.degree..
- 10. The display of claim 9, further comprising the steps of providing each of said negative biaxial retarders with retardation values d.multidot.(n.sub.x -n.sub.y) of from about 3 to 20 nm and each of said positive retarders with retardation values d.multidot..delta.n of from about 80 to 200 nm.
- 11. A twisted nematic liquid crystal display comprising:
- a twisted nematic liquid crystal layer for twisting at least one visible wavelength of normally incident light emitted from a backlight from about 80.degree. to 100.degree. when in the off-state;
- a positive retarder having a retardation value of from about 80 to 200 nm; and
- a negative biaxial retarder defined by n.sub.x >n.sub.y >n.sub.z having a retardation value d.multidot.(n.sub.x -n.sub.z) of from about 50 to 150 nm, said negative biaxial retarder being disposed between said liquid crystal layer and said positive retarder.
- 12. A twisted nematic liquid crystal display comprising:
- a twisted nematic liquid crystal layer for twisting at least one visible wavelength of normally incident light emitted from a backlight from about 80.degree. to 100.degree. when the liquid crystal layer is in the off-state;
- a positive retarder; and
- a negative biaxial retarder defined by n.sub.x >n.sub.y >n.sub.z, said negative biaxial retarder having a retardation value d.multidot.(n.sub.x -n.sub.z) of from about 100 to 200 nm.
- 13. The twisted nematic liquid crystal display of claim 12, wherein said positive retarder has a retardation value of from about 80 to 200 nm; and the display exhibits a maximum contrast ratio of at least about 300 when about 5.5 driving volts are applied in the on-state.
- 14. The twisted nematic liquid crystal display of claim 13, wherein the display is of the normally white type, and wherein the negative biaxial retarder is disposed between said liquid crystal layer and said positive retarder.
- 15. A normally white twisted nematic liquid crystal display comprising:
- a liquid crystal layer for twisting at least one normally incident visible wavelength of light as it passes therethrough when said liquid crystal layer is in substantially the off-state so as to define a twisted nematic normally white display;
- a negative biaxial retarder means located on one side of said liquid crystal layer and having a retardation value d.multidot.(n.sub.x -n.sub.z) of from about 70-300 nm and a retardation value d.multidot.(n.sub.x -n.sub.y) of from about 1-40 nm;
- a positive retarder means on the same side of said liquid crystal layer as said negative biaxial retarder means, said positive retarder means having a retardation value of from about 80-200 nm; and
- wherein said negative biaxial retarder means is defined by n.sub.x >n.sub.y >n.sub.z.
- 16. The display of claim 15, wherein positive retarder means is uniaxial and said liquid crystal layer twists at least one normally incident visible wavelength of light from about 80.degree.-100.degree. as it passes therethrough when said liquid crystal layer is in substantially the off-state;
- wherein said biaxial retarder means is made up of at least two separate retarder sheets laminated together;
- wherein said biaxial retarder means has a retardation value d.multidot.(n.sub.x -n.sub.z) of from about 70 to 260 nm; and
- wherein said negative biaxial retarder means and said positive retarder means are on the rear side of said liquid crystal layer so as to reduce reflections off of the front of the display.
- 17. The display of claim 16, wherein said negative biaxial retarder means has a retardation value d.multidot.(n.sub.x -n.sub.z) of from about 70-130 nm and a retardation value d.multidot.(n.sub.x -n.sub.y) of from about 3-20 nm.
- 18. A normally white LCD comprising:
- a liquid crystal layer;
- a positive uniaxial retarder on a first side of said liquid crystal layer;
- a biaxial retarder on said first side of said liquid crystal layer; and
- an air gap defining an isotropic layer, said air gap located on said first side of said liquid crystal layer, so as to improve viewing characteristics of the display.
- 19. A normally white twisted nematic LCD comprising:
- a twisted nematic liquid crystal layer for twisting at least one normally incident wavelength of light from about 80.degree.-100.degree. as it passes therethrough when said liquid crystal layer is in substantially the off-state thereby defining a twisted nematic display; and
- first and second retardation members oriented relative to one another so that the LCD outputs a contrast ratio of at least about 300:1 at a predetermined viewing angle when approximately 5.5 volts are applied across said liquid crystal layer in the on-state.
Parent Case Info
This application is a continuation-in-part (CIP) of Ser. No. 08/559,275, filed Nov. 15, 1995 (now U.S. Pat. No. 5,657,140), which is a CIP of Ser. No. 08/167,652, filed Dec. 15, 1993 (now U.S. Pat. No. 5,570,214), and this application is also a CIP of 08/711,797, filed Sep. 10, 1996, which is a continuation of 08/167,652, filed Dec. 15, 1993, (now U.S. Pat. No. 5,570,214), the disclosures of which are all hereby incorporated herein by reference.
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Foreign Referenced Citations (5)
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4-56802 |
Feb 1992 |
JPX |
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Continuations (1)
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Date |
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Parent |
167652 |
Dec 1993 |
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Continuation in Parts (3)
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Number |
Date |
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Parent |
559275 |
Nov 1995 |
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Parent |
167652 |
Dec 1993 |
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Parent |
711797 |
Sep 1996 |
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