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US 6,191,893 B1Granted
Color projection display system with improved hue variation
AssigneePhilips Electronics North America Corporation
InventorRalph Bradley
Life of this patent
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Abstract
In a color projection display system having a source of white light, an electro-optic light modulator for modulating the light in accordance with a display signal, a projection lens, and dichroic filters for separating the white light into color components prior to modulation, and for recombining the modulated color components prior to projection, the color uniformity of the display is improved by designing the filters to have different cut-off wavelengths of separation and recombination for at least one of the color components.
Claims14
A color projection display system comprising:
- a white light illumination source, a projection lens, and at least one electro-optic light modulator disposed in an optical path between said illumination source and said projection lens,
- a first set of dichroic filters disposed between said illumination source and said at least one electro-optic light modulator, to separate the white light into color components, one of the filters of the first set having at least a first given cut-off wavelength for separating a first color component from at least one of the other color components, and another of the filters of the first set having at least a second given cut-off wavelength for separating a second given color component from at least one of the other color components,
- a second set of dichroic filters to recombine these components, and
- means for causing said light modulator to modulate at least one of said color components,
- characterized in that one of the dichroic filters of the second set combines at least said first color component with at least one of the other color components, and has a third given cut-off wavelength different from said first given cut-off wavelength and different from said second given cut-off wavelength.
2 more elements
Dependencies are inferred from the claim text.