ENCODER FOR DECIDING ABSOLUTE POSITION AND SERVOMOTOR USING SAME

摘要

PURPOSE:To obtain an encoder which has a small size, simple structure, and middle-class absolute position resolution and a servo motor using the encoder by putting information related to an absolute position between outputs from two incremental phases which are different from each other in magnetizing pitch or optical property differing pitch. CONSTITUTION:The first incremental phase 12 is formed at the first prescribed pitch, namely, the first magnetizing pitch or optical property differing pitch lambda1 and the second phase 13 is formed at the second pitch, namely, the second magnetizing pitch or optical property differing pitch lambda2. Information related to an absolute position is put on the phase difference produced between the outputs of the first and second sensor groups 14 brought nearer to each incremental phase. An absolute deciding means adds a modulated sin signal or cos signal to the output of each sensor group and finds the phase difference, namely, absolute position by performing an electrical process. In addition, a servo motor decides an address for generating sine wave current based on the output of this encoder.