| 摘要 |
PURPOSE:To shorten a time of phase fluctuation by rotating a motor uniformly independently of load fluctuation when a magnetic head is moved to another recording track, and reducing the amount of phase fluctuation when may be generated then. CONSTITUTION:In a speed control system 20, the output frequency of an FG 9 is converted to a voltage by an F/V 21 and this voltage is amplified by a phase compensating amplifier 23 to drive a motor 12 through an adding circuit 24, and the rotation frequency is kept constant. In a phase control system 25, the signal from a vertical synchronizing signal circuit 26 and the signal from a tack 7 are compared with each other by a phase comparing circuit 27, and the output of this circuit 27 passes a phase compensating amplifier 28 and is added to the output of the speed control system 20 by an adding circuit 24, and relations between a recording signal switching point and a vertical synchronizing signal recording position are kept. An adding circuit 22 is provided, and the pulse which drives a pulse motor driving circuit 18 is not only applied to a pulse motor 19 but also added to the speed control system 20, and the voltage applied to the motor is raised to increase temporarily the driving torque when the head is moved to another track. |
