| 摘要 |
<p>PURPOSE:To uniformly generate contrast by eliminating necessity for a heater to miniaturize a device total unit further to eliminate unevenness of temperature on a light shutter. CONSTITUTION:An infrared ray cut filter 5 for absorbing an infrared light component of a light source 3 and a filter switching roller 12 for moving the infrared ray cut filter 5 in an optical path between the light source 3 and a light shutter 6 are provided. That is, in the case of high temperature of the light shutter 6, the filter 5 is inserted between the light source 3 and the light shutter 6 to suppress infrared light radiated to the light shutter 6. In the case of low temperature of the light shutter 6, the infrared light is radiated to the light shutter 6 by not inserting the filter 5. Accordignly, the infrared light, radiated to the shutter 6, is adjusted, so that the temperature of the shutter 6 can be uniformly adjusted to a predetermined temperature.</p> |
