Patent ID: 6417503
Filing Date: 2002-07-09
Classification: H03G,H03M

Abstract:
An optical sensor circuit for outputting an analog signal indicating a quantity of received light to an A/D converter, comprising:a light detector element for detecting light and outputting a photo-current indicating a quantity of the detected light; light quantity accumulating means connected to the light detector element for receiving the photo-current, said light quantity accumulating means accumulating the photo-current for a predetermined period of time and outputting an analog signal indicating an accumulated quantity of the detected light as a quantity of change with respect to a reference voltage; and output range changing means connected to an input of the light quantity accumulating means, said output range changing means changing an output range of the analog signal outputted from the light quantity accumulating means according to an input range of the A/D converter, said output range changing means including a plurality of reference voltage generating means outputting voltages different from each other, and reference voltage selecting means selecting one of outputs of the reference voltage generating means, said reference voltage selecting means feeding the selected output to the light quantity accumulating means as the reference voltage thereof so that an output range of the sensor circuit is adjusted to accord the input range of the A/D converter.