Color display system
First Claim
Patent Images
1. A display apparatus including a display subassembly, the display subassembly comprising:
- first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting the characteristic wherein they switch rapidly between a deselected state and a selected state when an excitation voltage applied thereto exceeds a threshold value;
first, second, third and fourth polarizers;
the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers;
the birefringence of the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the panels are in first states, and to pass substantially all colors of light when the panels are in second states;
each of said panels having a plurality of electronically operable pixels, said panels being stacked so that corresponding pixels in each of said panels are aligned along an axis orthogonal thereto;
the apparatus further including;
illumination means for illuminating the display subassembly with substantially collimated light; and
light processing means for processing the collimated light exiting the display subassembly to permit wide angle viewing.
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Abstract
A preferred display system is formed by stacking three STN birefringent LCD panels that are tuned to different subtractive primary colors (i.e. yellow, cyan and magenta). Interposed between the panels, and sandwiched about the stack, are polarizers. At least some of the polarizers may be colored to enhance the birefringence color characteristics and to improve brightness. In some embodiments, the assembly is illuminated by a collimated light source and the resulting image is focused onto a projection screen for viewing. In other embodiments, optics are provided to permit direct wide angle viewing of the display without parallax effects.
216 Citations
23 Claims
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1. A display apparatus including a display subassembly, the display subassembly comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting the characteristic wherein they switch rapidly between a deselected state and a selected state when an excitation voltage applied thereto exceeds a threshold value; first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; the birefringence of the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the panels are in first states, and to pass substantially all colors of light when the panels are in second states; each of said panels having a plurality of electronically operable pixels, said panels being stacked so that corresponding pixels in each of said panels are aligned along an axis orthogonal thereto; the apparatus further including; illumination means for illuminating the display subassembly with substantially collimated light; and light processing means for processing the collimated light exiting the display subassembly to permit wide angle viewing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A display apparatus including a display subassembly, the display subassembly comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting the characteristic wherein they switch rapidly between a deselected state and a selected state when an excitation voltage applied thereto exceeds a threshold value; first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; the birefringence of the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the panels are in first states, and to pass substantially all colors of light when the panels are in second states; each of said panels having a plurality of electronically operable pixels, said panels being stacked so that corresponding pixels in each of said panels are aligned along an axis orthogonal thereto; the apparatus further including; illumination means for illuminating the display subassembly with substantially collimated light; and light processing means for processing the collimated light exiting the display subassembly to permit wide angle viewing; a display housing for containing the display subassembly, the illumination means and the processing means; and coupling means for coupling the display subassembly to a portable computer through the display housing, said coupling means permitting the display housing to be positioned in a first position in which the processing means can be viewed for use, said coupling means further permitting the display housing to be positioned in a second position in which the processing means is protected from abuse and can not be viewed for use. - View Dependent Claims (13)
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14. A display apparatus including a display subassembly, the display subassembly comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting the characteristic wherein they switch rapidly between a deselected state and a selected state when an excitation voltage applied thereto exceeds a threshold value; first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; the birefringence of the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the panels are in first states, and to pass substantially all colors of light when the panels are in second states; each of said panels having a plurality of electronically operable pixels, said panels being stacked so that corresponding pixels in each of said panels are aligned along an axis orthogonal thereto; the apparatus further including; illumination means for illuminating the display subassembly with substantially collimated light; and light processing means for processing the collimated light exiting the display subassembly to permit wide angle viewing; the illumination means includes a point source immovably fastened to a case of a portable computer; the display subassembly includes hinge means for mounting to the computer case, said hinge means permitting positioning of the display subassembly in a first position in which the processing means can be viewed for use, said hinge means further permitting the display subassembly to be positioned in a second position in which the display subassembly is substantially parallel to the computer case; wherein the illumination means is positioned to illuminate the display subassembly from a rear side thereof when the display subassembly is in its first position. - View Dependent Claims (15)
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16. A display apparatus including a display subassembly, the display subassembly comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting the characteristic wherein they switch rapidly between a deselected state and a selected state when an excitation voltage applied thereto exceeds a threshold value; first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; the birefringence of the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the panels are in first states, and to pass substantially all colors of light when the panels are in second states; each of said panels having a plurality of electronically operable pixels, said panels being stacked so that corresponding pixels in each of said panels are aligned along an axis orthogonal thereto; the apparatus further including; illumination means for illuminating the display subassembly with substantially collimated light; and light processing means for processing the collimated light exiting the display subassembly to permit wide angle viewing; hinge means for mounting the display subassembly to a top portion of a portable computer case, said hinge means permitting positioning of the display subassembly in a first position in which the processing means can be viewed for use, said hinge means further permitting the display subassembly to be folded towards a rear portion of the case to a second position in which the display subassembly is substantially parallel to a top portion of the computer case;
the apparatus further including means for protecting the display subassembly from abuse when in its second position.
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17. A display apparatus comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting a total twist angle greater than or equal to 180° and
less than 360°
, each of said panels having a plurality of electronically operable pixels, each of the pixels exhibiting a birefringent effect that varies in response to a signal applied thereto;first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; and the birefringence of pixels in the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the pixels are in first states, and to pass substantially all colors of light when the pixels are in second states.
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18. A display apparatus comprising:
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first, second and third supertwisted nematic birefringent liquid crystal display panels, each of said panels exhibiting a total twist angle greater than or equal to 180° and
less than 360°
, each of said panels having a plurality of electronically operable pixels, each of the pixels exhibiting a birefringent effect that varies in response to a signal applied thereto;first, second, third and fourth polarizers; the first panel being positioned between the first and second polarizers, the second panel being positioned between the second and third polarizers and the third panel being positioned between the third and fourth polarizers; and the birefringence of pixels in the first, second and third panels being selected, in cooperation with operation of the polarizers adjacent thereto, to pass light of first, second and third subtractive primary colors, respectively, when the pixels are in first states, and to pass substantially all colors of light when the pixels are in second states; the apparatus further including; a case in which the liquid crystal panels and polarizers are mounted, said case being adapted for positioning on an overhead projector; a first Fresnel lens for collimating light converging from a display surface of an overhead projector and for illuminating the panels with said collimated light, said first Fresnel lens being disposed in the case; and a second Fresnel lens for collecting collimated light exiting the panels and focusing said collimated light into a projection lens of an overhead projector, said second Fresnel lens also being disposed in the case.
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19. A color display apparatus comprising:
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first and second assemblies, each of the assemblies comprising a supertwisted nematic liquid crystal panel, each of the panels exhibiting a total twist angle greater than or equal to 180° and
less than 360° and
having a plurality of pixels, each of the assemblies exhibiting a birefringent effect that varies in response to an excitation signal applied to the panel therein;a first polarizer interposed between the assemblies; and second and third polarizers sandwiched about the assemblies; wherein the assemblies are tuned so that a birefringent effect exhibited by the first assembly when a first signal is applied thereto differs from a birefringent effect exhibited by the second assembly when the same first signal is applied thereto. - View Dependent Claims (20, 21)
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22. A color display apparatus comprising:
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first and second assemblies, each of the assemblies comprising a supertwisted nematic liquid crystal panel, each of the panels exhibiting a total twist angle greater than or equal to 180° and
less than 360° and
having a plurality of pixels, each of the assemblies exhibiting a birefringent effect that varies in response to an excitation signal applied to the panel therein;a first polarizer interposed between the assemblies; and second and third polarizers sandwiched about the assemblies; wherein the assemblies are tuned so that a birefringent effect exhibited by the first assembly when a first signal is applied thereto differs from a birefringent effect exhibited by the second assembly when the same first signal is applied thereto; the apparatus further including; a case in which the liquid crystal panels and polarizers are mounted, said case being adapted for positioning on an overhead projector. - View Dependent Claims (23)
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Specification