Patent ID: 7289189

Claim:
A color liquid crystal display of passive matrix design comprising: a polarizer; an analyzer having a transmission axis; and at least one light generation stage positioned between said polarizer and said analyzer for transmitting light of controlled wavelengths to the analyzer, the light generation stage including: a first retarder stack that rotates controlled wavelengths of light to a particular polarization state, a second retarder stack inverted and rotated by about 90 degrees with respect to said first retarder stack, and a passive matrix addressed optical element including a first twisted liquid crystal cell and a compensator, said element positioned between said first and second retarder stacks, said compensator being selected from the group consisting of (a) a second twisted liquid crystal cell, fixed in one of the states of said first twisted liquid crystal cell and having an opposite twist sense, and (b) a birefringent film composite constructed to cancel the optical effect of said first twisted liquid crystal cell in one of its states, wherein said compensator ideally cancels the optical effect of said first twisted liquid crystal cell when said first twisted liquid crystal cell is in a first state, and wherein said compensator does not cancel the optical effect of said first twisted liquid crystal cell when said first twisted liquid crystal cell is not in said first state, and the retardation and orientation of said first retarder stack, said second retarder stack, and said first twisted liquid crystal cell are optimized so as to provide a color generation stage that, according to the state that said first twisted liquid crystal cell is in, selectively causes said controlled wavelengths of light to be polarized along the transmission axis of said analyzer, while not affecting the polarization state of uncontrolled wavelengths.