| 摘要 |
PURPOSE:To enable speed/phase control in simple and inexpensive circuit constitution, by a method wherein current flowing in a brush is differentiated and motor rotational phase is detected. CONSTITUTION:A phase detection circuit 2 differentiates current flowing in a brush of a DC motor 1, and detects rotational phase of the DC motor 1. Reference frequency signal from the reference frequency generator 3 and phase detection signal from a phase detection circuit 2 are transmitted to a phase comparator 4 and compared in phase. A counter electromotive force servo circuit 5 detects counter electromotive force of the motor 1 from the current flowing in the motor 1, and controls a control element based on adding output of the counter electromotive force detection signal and the output signal from the phase comparator 4. In this constitution, a speed/phase servo can be realized without necessitating a phase sensor and a speed sensor. |
