Patent ID: 6597007
Filing Date: 2003-07-22
Classification: G01C,G01S

Abstract:
An optical position detecting device comprising:a semiconductor position detection element that photoelectrically converts an incident beam into carriers and outputs a first signal current from a first output terminal and outputs a second signal current from a second output terminal in response to the position of incidence of this beam; a first current/voltage conversion unit that inputs said first signal current that is output from said first output terminal of said semiconductor position detecting element and outputs a first signal voltage in accordance with this first signal current; a second current/voltage conversion unit that inputs said second signal current that is output from said second output terminal of said semiconductor position detecting element and outputs a second signal voltage in accordance with this second signal current; a selection circuit that compares the magnitude of the respective values of said first signal voltage output from said first current/voltage conversion unit and said second signal voltage output from said second current/voltage conversion unit and that outputs a comparison signal indicating the result of this comparison and, of said first and said second signal voltages, selects and outputs a maximum signal whose voltage is the larger and a minimum signal whose voltage is the smaller; an A/D conversion circuit that sets an A/D conversion range in accordance with said maximum signal output from said selection circuit, converts said minimum signal output from said selection circuit into a digital signal, and outputs this digital signal; and an incidence position calculating unit that finds the incidence position of the beam on said semiconductor position detecting element, using said comparison signal output from said selection circuit and said digital signal output from said A/D conversion circuit.