| 摘要 |
PCT No. PCT/JP81/00313 Sec. 371 Date Jun. 23, 1982 Sec. 102(e) Date Jun. 23, 1982 PCT Filed Oct. 29, 1981 PCT Pub. No. WO82/01594 PCT Pub. Date May 13, 1982.A system for detecting the rotational speed of a rotating body comprising the steps of generating two kinds of signals A and B having alternating wave forms and corresponding to the rotational speed of the rotating body by means of position-detecting devices (5a, 5b), the signals A and B having the same amplitude and having phases deviating by 90 DEG , producing switching signals S(A), S( &upbar& A), S(B), and S( &upbar& B) from the signals A and B by means of zero-cross circuits (711, 712), producing inverted signals &upbar& A and &upbar& B from the signals A and B by means of inverter circuits (72, 73), producing differentiation signals dA, &upbar& d, dB, and &upbar& d by supplying the signals A, &upbar& A, B and &upbar& B to differentiation circuits (74, 75, 76, 77), and obtaining output signals corresponding to the rotational speed of the rotating body by selectively switching the differentiation signals dA, &upbar& d, dB, and &upbar& d in a switching circuit 78 by means of the switching signals S(A), S( &upbar& A), S(B), and S( &upbar& B), thereby detecting the rotational speed of the rotating body.
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