| 摘要 |
PURPOSE:To prevent the erroneous counting of the counter of the rotary position detector of a rotary body cooperated with the steering wheel of a car, by judg ing an origin position where the integrated value within the predetermined time of a stop time becomes max as center position of a rotary body. CONSTITUTION:Signals corresponding to a direction of rotation due to two sets of photointerruptors outputting signals different by 90 deg. from light passing through the slits provided on the rotary body cooperated with a steering wheel at an equal interval are counted by the counter 5 changed over by an increment/ decrement change-over circuit 5. This count value is compared with respective + or -one-rotation reference values N1, N2 by comparators 8, 10, 9 to control the opening of AND gates 11, 13, 12. The reference clock through an AND gate 14 opened by an origin position detection signal due to the origin position slit of the rotary body is counted for a predetermined time due to a monostable multivibrator 34 by counters 16-18 through the gates 11-13. An origin position where the integrated value becomes max is judged as the center position of the rotary body by comparators 23-25 and a decoder 26 and the counter 6 is reset by the judge output to correct erroneous counting.
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