| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability relative to failures of a transmission system, in an encoder which outputs an A-phase pulse signal, a B-phase pulse signal and a Z-phase pulse signal which are sifted in phase from each other, and which transmits abnormalities in the A-phase and B-phase pulse signals to the output state of the Z-phase pulse signal. SOLUTION: The encoder is equipped with comparators CP4, CP5 for detecting a state in which each output voltage signal deviates from the range of a normal operation, with respect to the A-phase and B-phase signals; and transistors TR4, TR5 which are connected to the output line of Z-phase signal via resistors R8, R18 respectively, and operate, in response to the outputs from respective comparators. When each output line, connected to output terminals QA, QB of the A-phase and B-phase signals is short-circuited to the ground, or each of signal lines 41A, 41B connecting the output terminals with an electronic control unit 40 is broken, the transistors TR4, TR5 are turned on, whereby the output of the Z-phase signal is made lower than its normal range, and the abnormality is detected. Even if either of the transistors of the A-phase or B-phase signal is at failure, abnormality of the other phase signal is transmitted to the Z-phase signal. COPYRIGHT: (C)2005,JPO&NCIPI
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