| 摘要 |
PURPOSE:To eliminate the influence of light distribution unevenness and to perform accurate dimming by allowing a photodetecting element to detect light reflected by a closed shutter blade and perform the dimming automatically. CONSTITUTION:The connector 3 of an endoscope is pluged in a socket 2 and a light source lamp 5 is turned on. Projection light from the lamp 5 is transmitted through the filter 9 of a turret 8 and converged through a condenser lens 6 to travel to the incidence end surface 4a of a light guide tube 4, but a shutter blade 15 is normally closed and positioned on an optical path (l) of projection, so the light is cut off by the shutter blade 15 and never incident to the incidence end surface 4a. On the other hand, the projection light transmitted through a stop blade 16 is reflected by the reflecting surface 21 of the shutter blade 15 into diffused light, which passes through the small hole 24 of a light shield box 22 to enter a photodetecting element 22 to detect its quantity of light. This detection information is used to vary an aperture value and switch the filter 9, and the quantity of projection light of the light source lamp 5 is adjusted to make an automatic adjustment to the proper quantity of light. |
