| 摘要 |
PURPOSE:To prevent generation of a nonstabilizing state without giving to a lighting device a superfluous quality, by controlling a light source by detecting an optical output of the light source, and also generating an alarm in case when a variation of the optical output exceeds a prescribed value. CONSTITUTION:An optical output of a light source 2 such as a fluorescent lamp, etc. is detected by a photodiode 4, etc., and a dimming stabilizer 20 is controlled through a controlling circuit 10 which is equipped with an operational amplifier, etc. As a result, a current to be applied to the light source 2 is controlled and the extent of exposure of an original 1 is stabilized. On the other hand, the extent of detection of the optical output by the diode 4 is compared with a prescribed reference value, and when it gets out of the control range of the stabilizer 20, an alarm is generated in accordance with a comparison output, and an occurrence of the nonstabilizable state of the exposure is prevented without giving to the lighting device a superfluous quality. |
