| 摘要 |
An encoder includes comparators CP 4 and CP 5 which are provided in such a manner as to correspond to phase A and B respectively and detect a state where the output voltages deviate from their normal ranges. Transistors TR 4 and TR 5 which operate according to the outputs of the respective corresponding comparators are connected through resistors R 8 and R 18, respectively, to an output line of phase Z. When each output line connecting to a phase-A output terminal QA or a phase-B output terminal QB is short-circuited to ground, or a signal line 41 A or 42 B connecting the output terminal with a electronic control unit 40 is broken, the transistor TR 4 or TR 5 is turned on and the output of phase Z falls below its normal range, thereby a malfunction is detected. Even if one of the transistors of phase A and phase B breaks down, a malfunction in the other phase is transmitted to phase.
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