Patent ID: 8681192
Filing Date: 2014-03-25
Classification: H03K

Abstract:
1. A sensor device capable of serving as a proximity sensor for determining whether a detection target is positioned proximately or not, comprising: a light emitting element for emitting, to a predetermined space, light to be reflected by the detection target positioned proximately; an analog-to-digital conversion section for subjecting an analog input current to analog-to-digital conversion; a light receiving element which is a photodiode, whose cathode is connected with an input terminal of the analog-to-digital conversion section and whose anode is grounded electrically; a comparison section for receiving, at one of two input terminals, a result of analog-to-digital conversion by the analog-to-digital conversion section and receiving a predetermined threshold at the other of the two input terminals, comparing the result with the predetermined threshold, and when the result is larger than the predetermined threshold, outputting a signal indicating that the detection target is positioned proximately and when the result is not larger than the predetermined threshold, outputting a signal indicating that the detection target is not positioned proximately; a storage section for storing the result; a change-over switch whose first terminal is connected with said one of the two input terminals of the comparison section, whose second terminal is connected with an input terminal of the analog-to-digital conversion section and an input terminal of the storage section, and whose third terminal is grounded electrically, the change-over switch connecting the first terminal with the second terminal or connecting the first terminal with the third terminal so as to make said one of the two input terminals of the comparison section grounded electrically; an open-close switch whose one end is connected with the cathode of the light receiving element and the input terminal of the analog-to-digital conversion section; a variable current source whose input terminal receives application of a power source voltage and whose output terminal is connected with the other end of the open-close switch; and a switch control section for outputting, to a control input terminal of the open-close switch, a first control signal for controlling opening and closing of the open-close switch and outputting, to a control input terminal of the change-over switch, a second control signal for controlling switching of the change-over switch.