| 摘要 |
PROBLEM TO BE SOLVED: To provide a projector optical device having an image forming section and a screen held stationary in their fixed locations having a fixed object image distance, wherein an effect from a variation of optical characteristics caused by heat, such as a variation of focal length of a lens in a projection lens system located in the vicinity of a light source, can be eliminated and thereby a clear image in the initial focused condition can be maintained on the screen. SOLUTION: In the projector optical device including a retro-focus projection lens system, at least a partial lenses of a convex lens group on the light source side of the retro-focus projection lens system are supported by a plurality of compensation members expanding and contracting in the direction of an optical axis in response to a temperature change, and the variance of the object image distance due to the variance of the focal distance caused by a temperature change of the convex lens group is compensated by differences of expansion or contraction of the compensation members resultant from the temperature change. COPYRIGHT: (C)2006,JPO&NCIPI
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