| 摘要 |
PURPOSE:To stably control a speed by providing a gate circuit for determining the valid zone of an output position of a reference signal for resetting an accurate rotor position signal. CONSTITUTION:A Z-phase valid zone having a pulse width of -30 -30 deg. is formed at a reference position of a reference signal 102 for resetting an accurate rotor position signal 111 as a mid-point by a signal output from an AND circuit 115 through AND circuits 115, 116 and a NOT circuit 117 in a reference signal gate circuit 114. When the signal 102 is input to the AND circuit 116 in the zone, a reset signal 119 is output to reset an up/down counter 109. Accordingly, even if the signal 102 is deviated at its output position from an intrinsic position by the influence of a noise, etc., if it is output within the output position valid zone of the signal 102, the reset signal 109 is always output at each one revolution of a rotor to reset the counter 109. |
