| 摘要 |
PURPOSE:To make it possible to remove AC background light, by guiding out an output, which undergoes photoelectric conversion and current-voltage conversion, to a load for removing the AC background light at the next stage through a capacitor. CONSTITUTION:A first, before light is projected on an object, a constant output voltage is guided out of a load 13 for removing background light by the nonoperating state of a switching means 16. Therefore, the potential at one side of a capacitor 12 is always constant. Since one side of the capacitor 12 is at the potential of the constant voltage output, said side has low impedance. In the capacitor 12, the electric charge corresponding to the output of photoelectric conversion at that time point is stored without time delay. When the light is projected, the output of a constant voltage circuit 15 is cut off from the load 13 by the switching means 16 in synchronization with the light projection. The reflected light from the object, on which the light is projected, undergoes photoelectric conversion and current-voltage conversion. The voltage is transmitted to the load 13 through the capacitor 12, and the output of the load 13 is changed. At this time, the timing of the latching is synchronized with the timing of the light projection as close as possible. Therefore, the detected output of a distance, in which the effect of the AC background light is negligible, can be obtained. |
