| 摘要 |
PURPOSE:To detect the abnormality of a short period rotary encoder, when the rotation signal from the same rotary body having the different period, i.e., the counted value at the reset time of a counter, does not reach the number corresponding to the ratio of the periods of two rotary encoders. CONSTITUTION:A lone period rotary encoder 4 and a short period rotary encoder 5 are coaxially attached to a crank shaft. At every time the crankshaft is rotated by one half, pulse currents with different periods are supplied to a microcomputer 6 for controlling an engine and wire breakdown detector 7 from exciting coils 4c and 5c. When the rotary encoder 5 fails or a transmission line 51 is broken, both the output of a counter 10 and the output of a decoder 11 disappear. As a result, when the output of a differential circuit 8 is first applied to a flip flop circuit 12 after the occurrence of the fault, the flip flop circuit 12 is reset. This is caused by the lack of data input since the counted value of the counter 10 does not reach (n). The occurrence of the fault is noticed to the microcomputer 6. |
