| 摘要 |
PURPOSE:To detect the abnormality of a long period rotary encoder when the counted value of a counter exceeds the number corresponding to the ratio between the periods of two rotary encoders, by obtaining the rotation signals having the different periods from the same rotary body. CONSTITUTION:A long period rotary encoder 4 and a short period rotary encoder 5 are coaxially attached to a crank shaft. Pulse currents having the different periods are supplied to a microcomputer 6 and a wire breakdown detector 7 from exciting coils 4c and 5c. A counter 10 of the wire breakdown detector 7 counts the output of the short period rotary encoder 5. The counted content is reset by the output of the long period rotary encoder 4. When the rotary encoder 4 fails or a transmission line 41 is broken, the counter 10 is not reset. When the counted value of the counter 10 exceeds the number corresponding to the ratio between the periods of the two rotary encoders 4 and 5, a wire breakdown detection signal is outputted to the microcomputer 6. |
