| 摘要 |
PURPOSE: An optical system of an LCD projector is provided to reduce the thickness of entire system by shortening the component length of an optical system. CONSTITUTION: An optical system of an LCD projector consists of: a first dichroic mirror(52) arranged on an optical path reflected from a second full-reflecting mirror(50); a first PBSP(Polarizing Beam Split Prism,54A) formed on an optical path between the first dichroic mirror and a blue LCD panel(56A); a second PBSP(54B) on an optical path between the first dichroic mirror and a green LCD panel(56B), a first relay lens(60) between the second PBSP and a red LCD panel(56C), a third full-reflecting mirror(62), a second relay lens(64), fourth and fifth full-reflecting mirrors(66,68) and a third PBSP(54C); a dichroic prism(70) formed among the first to third PBSPs; a polarizing filter(58) between the second PBSP and the dichroic prism; and a projection lens(72) opposed to the beam transmission surface of the dichroic prism. The first dichroic mirror reflects red beam and transmits green and blue beam having shorter wavelength than red beam. The first PBSP reflects S type linearly-polarized beam to the blue LCD panel from the third full-reflecting mirror and P type linearly-polarized beam to the dichroic prism. The second PBSP has different reflection and transmission characteristics depending on linearly-polarized beam and wavelength. The second PBSP reduces the number of dichroic mirrors for color separation by performing color separation. Thereby, the component length(B) of the optical system is reduced. |
