| 摘要 |
PURPOSE:To make it possible to remove a bad influence which is exerted on measurement due to a variation of the quantity of light, by varying the frequency of a clock driver in accordance with a variation of the quantity of light of a reflected ray which is made incident to the solid image pickup element, so that the video output can be kept constant. CONSTITUTION:A light beam of the light source 1 is irradiated to an object to be measured A, and its reflected ray is made incident to the solid image pickup element 4. As for a part of this reflected ray, its variation is detected by the light quantity variation detector 12, and a voltage signal is able to obtain the frequency corresponding to a variation of the quantity of light by the V/F converter 14. A clock of this frequency is input to the clock driver 5, and the clock frequency is varied. That is to say, when the quantity of light is excessive, the clock frequency becomes large, and when it is too little, said frequency becomes small. In this case, since the video output voltage is in inverse proportion to the clock frequency, the output voltage of the solid image pickup element can be kept constant by varying the clock frequency in accordance with the quantity of light. In this way, a bad influence caused by a variation of the quantity of light can be removed. |
