| 摘要 |
PURPOSE:To obtain an object image whose light is always properly adjusted by providing a temperature adjustment means on a liquid crystal element having a light adjustment means and controlling the variation of the temperature of the liquid crystal element. CONSTITUTION:Plural heat insulating holders 5 covering the outer circumferential side surface of a liquid crystal filter 4 whose heat insulating effects are different are provided. Then, the temperature of the liquid crystal filter 4 is controlled to be varied by exchanging and using the plural heat insulating holders 5. Therefore, when the quantity of light is adjusted so that it is suitable for the observation of an image, even in case that a temperature difference exists between the temperature of the liquid crystal filter 4 and the ambient temperature of the insertion tip part of an endoscope or a temperature heated by the illumination light of a light guide 1, the temperature difference is almost cut to be conducted to the liquid crystal filter 4 by the heat insulating holders 5 and the liquid crystal filter 4 is maintained within a proper temperature range. Thus, the light shielding speed of the liquid crystal filter 4 can be adjusted by controlling the temperature thereof and the proper light adjustment according to necessity can be obtained. |
