| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a projection type video display device capable of detecting degree of degradation in an optical element. Ž<P>SOLUTION: The projection type video display device 100 includes: a first optical sensor 80a provided between a light source 10 and the optical element, and measuring illuminance of light emitted from the light source 10; a second optical sensor 80b provided between the optical element and the projection optical system, and measuring illuminance of light emitted from the optical element; and a detection part 220 detecting the degree of degradation R of the optical element on the basis of the measured results Da and Db of the first optical sensor 80a and the second optical sensor 80b. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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