Projection apparatus with a polarizer, glass panel, and quarter-waveplate at light exit side of liquid crystal

An optical device comprising:

• a plurality of polarizing plates for polarizing a plurality of beams;
• a plurality of optical filters into which said plurality of beams polarized by said plurality of polarizing plates are introduced;
• a prism for combining said beams emitted from said plurality of optical filters;
• and
• at least one quarter-wave plate disposed between each of said plurality of polarizing plates and a corresponding one of said plurality of optical filters,
• wherein said plurality of optical filters and said prism include at least a plurality of second quarter-wave plates, each disposed between one of said plurality of optical filters and said prism.

The liquid-crystal projector comprising:

• a first liquid-crystal display device including a first liquid-crystal panel into which a beam of a first color is introduced and a first pair of polarizing plates disposed at a beam input side and a beam output side, respectively, of said first liquid-crystal panel;
• a second liquid-crystal display device including a second liquid-crystal panel into which a beam of a second color is introduced and a second pair of polarizing plates disposed at a beam input side and a beam output side, respectively, of said second liquid-crystal panel;
• a third liquid-crystal display device including a third liquid-crystal panel into which a beam of a third color is introduced and a third pair of polarizing plates disposed at a beam input side and a beam output side, respectively, of said third liquid-crystal panel;
• a first dichroic mirror disposed at said beam output side of said first liquid-crystal display device for passing said beam of said first color and reflecting said beams of said second and third colors;
• a second dichroic mirror disposed at said beam output side of said second liquid-crystal display device for passing said beam of said second color and reflecting said beams of said first and third colors;
• a third dichroic mirror disposed at said beam output side of said third liquid-crystal display device for passing said beam of said third color and reflecting said beams of said first and second colors;
• a prism for combining said beams of said first, second and third colors Passed through said first, second and third dichroic mirrors, respectively;
• a lens for projecting a combined beam emitted from said prism;
• and
• first, second and third quarter-wave plates respectively disposed on beam output side polarizing plates of said first, second and third pairs of polarizing plates,
• wherein said first, second and third dichroic mirrors and said prism include fourth, fifth and sixth quarter-wave plates disposed between said prism and said first, second and third dichroic mirrors, respectively.

A liquid-crystal projector comprising:

• a first liquid-crystal display device including a first liquid-crystal Panel into which a beam of a first color is introduced and a first pair of polarizing elates disposed at a beam input side and a beam output side, respectively, of said first liquid-crystal panel;
• a second liquid-crystal display device including a second liquid-crystal panel into which a beam of a second color is introduced and a second pair of polarizing plates disposed at a beam input side and a beam output side, respectively, of said second liquid-crystal panel;
• a third liquid-crystal display device including a third liquid-crystal panel into which a beam of a third color is introduced and a third pair of polarizing plates disposed at a beam input side and a beam output side, respectively, of said third liquid-crystal panel;
• a first color filter disposed at said beam output side of said first liquid-crystal display device for passing said beam of said first color;
• a second color filter disposed at said beam output side of said second liquid-crystal display device for passing said beam of said second color;
• a dichroic mirror disposed at said beam output side of said third liquid-crystal display device for passing said beam of said third color and reflecting said beams of said first and second colors;
• a prism for combining said beams of said first, second and third colors passed through said first and second color filters and said dichroic mirror;
• a lens for projecting a combined beam emitted from said prism;
• and
• quarter-wave plates disposed on the beam output side polarizing plate of said third pair of polarizing plates at the side of said third beam output side polarizing plate from which said beam of said third color is emitted,
• wherein said dichroic mirror and said prism include a second quarter-wave plate disposed between said dichroic mirror and said prism.