| 摘要 |
PROBLEM TO BE SOLVED: To obtain an illuminating optical system used for a liquid crystal light valve capable of displaying a high-contrast, low-gradation video without causing a color change, and to obtain a projection display apparatus using the illuminating optical system. SOLUTION: The illuminating optical system includes: an optical device 4 that divides light from a light source system 3 into a plurality of partial light fluxes and emits the light fluxes, a light condensing device 6 that condenses the plurality of partial light fluxes so that they may be superposed on the liquid crystal light valve 2; and a light quantity adjusting mechanism 9 disposed on an optical path between the light source system 3 and the light condensing element 6, that adjusts a quantity of light with which the liquid crystal light valve 2 is irradiated by changing an aperture area on the optical path. Provided that the angle of the partial light flux to the normal line of the incident surface of the liquid crystal light valve 2 is defined as an incident angle, the light quantity adjusting mechanism 9 changes the aperture area so that the liquid crystal light valve 2 may be irradiated with the partial light flux having the maximum incident angle among the plurality of partial light fluxes. COPYRIGHT: (C)2009,JPO&INPIT
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