LIGHT-RECEIVING CIRCUIT OF ENCODER

PROBLEM TO BE SOLVED: To provide a light-receiving circuit of an encoder, capable of reducing the voltage width of hysteresis and acquiring detection signals of small phase errors, even if an input voltage to a comparator is reduced due to the reduced quantity of light-emission of a light emitting diode. SOLUTION: The light-receiving circuit of the encoder is provided with both a plurality of light-receiving circuit parts 8a for converting light, transmitted from a light-emitting element 1 through a plurality of slits formed in the encoder and received by a plurality of light-receiving elements 9a into electrical signals and the comparator 10 for converting the electrical signals into rectangular waves. The light-receiving elements 9a are connected to the positive input side of the comparator 10, a reference voltage 13 is connected to its negative input side, and a positive feedback resistor 12 is connected between its output side and the positive input side. A resistance potential dividing circuit 17 is provided between the output side and grounding terminal of the comparator 10, and one end of the positive feedback resistor 12 is connected to the resistive potential dividing circuit 17. The output voltage of the comparator 10 is divided by the resistance potential dividing circuit 17 to acquire divided voltages, and the divided voltages are positively fed back to the comparator. COPYRIGHT: (C)2005,JPO&NCIPI