| 摘要 |
PURPOSE:To expand the measuring range of a photoelectric converting element by detecting an output from the photoelectric converting element, and making the incident light on the photoelectric converting element variable. CONSTITUTION:The light which has transmitted through a light depreciating element 5 and has been made incident on a photoelectric converting element 1 is inputted to a comparator 4 through an amplifier 2. In this case, the comparator 4 having a hysteresis characteristic compares an output voltage of the amplifier 2, and a reference voltage of a reference voltage generator 3, generates an H level signal in case when the output voltage from the amplifier 2 is lower than the reference voltage, and generates a signal of an L level in case when said output voltage is higher than the reference voltage. When the signal of an L level has been generated, the transmittivity of the light depreciating element 5 is lowered in order to limit the incident light on the photoelectric converting element 1, and also switches a feedback resistance by interlocking an amplification degree changeover switch 6. In this way, in case when the light of a range being out of the linearity has been made incident, an output of the amplifier 2 of the photoelectric converting element 1 is detected, and the incident light is limited electrically, therefore, the measuring range of the photoelectric converting element 1 can be expanded. |
