Patent ID: 7690794

Claim:
A projection display apparatus comprising: first and second reflective light modulators for receiving incident light beams and impressing first and second images on corresponding returned light beams, each of said first and second reflective light modulators having light reflective pixel elements pivotal about respective rotation axes that are aligned in an alignment direction; a polarizing beam splitter having a beam splitting surface reflecting incident light in a first polarization as a reflected beam and transmitting incident light in a second polarization as a transmitted beam, a first port for receiving an incident light beam having said first and second polarizations, second and third ports for directing said reflected and transmitted beams toward said respective first and second reflective light modulators, said second and third ports also receiving first and second returned beams reflected by said respective first and second light modulators carrying said respective first and second images, and a fourth port for outputting a combined image beam comprising said first and second returned beams for projection onto a display screen; a first waveplate, placed between said second port of said polarizing beam-splitter and said first reflective light modulator, for converting light of said first polarization to said second polarization, whereby said reflected beam from said first reflective light modulator has said second polarization after passing through said first waveplate; and a second waveplate placed between said third port of said polarizing beam-splitter and said second reflective light modulator for converting light of said second polarization to said first polarization, whereby said reflected beam from said second reflective light modulator has said first polarization after passing through said second waveplate; and wherein said polarizing beam splitter has an incident plane defined by the normal of said beam splitting surface and said returned light beams carrying said impressed first and second images at said beam splitting surface; wherein said first and second light modulators are aligned so that the corresponding alignment directions of said first and second said light modulators are projected on to said fourth port as a common alignment direction; wherein said incident plane and said common alignment direction form an angle γ; and wherein said polarizing beam-splitter and said first and second reflective light modulators are oriented such that the angle γ is 0°≦γ≦45°.