| 摘要 |
PURPOSE:To make a signal processing circuit small in size and simple and to reduce the consumption of electric power while maintaining high accuracy by providing the signal processing circuit only to one output of the respective two outputs from one or two sets of photosemiconductor postion detecting elements (PSD). CONSTITUTION:When the output from a control circuit 18 is at an H level, a switching transistor 16 turns on, and a switching transistor 14 turns off. Then the terminal B of PSD2 is opened, and signal currents IA and IB are superposedly outputted from a terminal A. When the output from the circuit 18 goes to an L level, the TR16 turns off and the TR14 is turned on by the output from a constant current circuit 15. Then only the signal current IA is outputted from the terminal A of the PSD2 and the current IS from the trerminal B flows through the TR14 to a reference power source KVC. The current IA is subjected to a current-voltage conversion by an operational amplifier 11 and a load circuit 12 and after the current is amplified, the current is fed to a signal processing circuit 13 in the succeeding stage, where the current is calculated with the sum signal (VA+VB) latched at the H level and the signal corresponding to the incident position of the PSD which is normalized in VA/(VA+VB) is outputted. |
