Projection type liquid crystal display unit including orthogonal phase plates

Claim 1

A projection type liquid crystal display unit having a plurality of light paths for light of different wavelength regions, said display unit comprising: a first optical arrangement provided in a first one of the light paths and a second optical arrangement provided in a second one of the light paths, each of said first optical arrangement and said second optical arrangement including (a) a pair of polarizing means each having at least one of a light interruption axis and a light transmission axis, (b) a twist nematic liquid crystal cell having front and rear surfaces and an orientation twisted in a twist direction, said liquid crystal cell in each of said first one of said light paths and said second one of said light paths having substantially identical characteristics, and (c) a first phase plate disposed between said pair of polarizing means and having a retardation phase axis and a retardation value; wherein said first optical arrangement is characterized in that (i) one of a set angle of the orientation of the liquid crystal cell, a set angle of the retardation phase axis of said phase plate and a set angle of the one of the light interruption axis and the light transmission axis of said pair of polarizing means are different from those of the second optical arrangement, and (ii) said retardation value of said phase plate is different from that of the second optical arrangement, wherein at least one of said first and second optical arrangements has a second phase plate which is disposed between said pair of polarization means and has a retardation phase axis which is substantially orthogonal to said retardation phase axis of said first phase plate that is included in a same one of said first and second optical arrangements.