| 摘要 |
PURPOSE:To get accurate timing signal by feeding back a signal, which is made based on the voltage at the middle between the outputs of first and second integrating circuits, to the integrating circuit, in a driving circuit which applies a current based on the timing signal whose phase is delayed by a specified angle from the zero cross point of the counter electromotive voltage of a driving coil. CONSTITUTION:A feedback circuit 103 gets the voltage VCENT at the middle between the output signals K'1 and K'2 of integrating circuits 6 and 7, and feeds back the differential voltage with the reference voltage to amplifiers 101 and 102 as feedback voltage VB so as to give its noninverted signal VSY and inverted signal VSO. On the other hand, the polarities of the integrating circuits 6 and 7 are changed over by changing switch circuits S3 and S4 by the signal j from a buffer 8 and the signal j' from an inverter 9 of a signal g, which are inverted at each zero cross point of the counter electromotive voltage of each phase of a driving coil, and also the gain is controlled. Hereby, a timing signal, whose phase is delayed a specified angle accurately from the zero cross point of the counter electromotive force, can be gotten. |
