Patent ID: 6636276
Filing Date: 2003-10-21
Classification: H04N

Abstract:
A projection display system comprising:a light source adapted to supply an illumination light having common polarization at first and second sets of wavelengths; a wavelength-selective retarder device positioned to receive said illumination light from said light source and to produce a first dark-state light having a first polarization state at said first set of wavelengths and a second dark-state light having a second polarization state at said second set of wavelengths; a first reflective light valve device, comprising one or more light valves, adapted to receive said first dark-state light and to produce a first bright-state light by rotating the polarization from said first polarization state to said second polarization state; a second reflective light valve device, comprising one or more light valves, adapted to receive said second dark-state light and to produce a second bright-state light by rotating the polarization from said second polarization state to said first polarization state; wherein the assignment of said first and second sets of wavelengths to said first and second reflective light valve devices is switched sequentially in time; a light splitting and combining device positioned between said wavelength-selective retarder device and said first and second reflective light valve devices, said light splitting and combining device adapted to receive said first and second dark-state lights from said wavelength-selective retarder device and to direct said first and second dark-state lights to said first and second reflective light valve devices respectively, and adapted to receive said first and second bright-state lights reflected from said first and second reflective light valve devices respectively and to direct said first and second bright-state lights as a combined beam to a screen; and a wavelength-selective filtering device positioned to receive said combined beam containing said first and second bright-state lights from said light splitting and combining device and to substantially eliminate a residual dark-state light from said first and second light valve devices, wherein the wavelength-selective filtering device passes a beam containing all of red, blue and green primary color components of a color image which is projected onto the screen with improved contrast.