| 摘要 |
PURPOSE:To similarly approximate the recording densities at the inner and outer peripheral surfaces of a disk by switching the time constant of a speed controller to control to switch the rotating speed of a motor in a plurality of stages. CONSTITUTION:An oscillating frequency in response to the rotating speed is induced by a signal generator 11 by the rotation of the rotor of a motor 12, and the signal of the frequency is input to a speed controller 17. The controller 17 generates a voltage 19 proportional to the input frequency. This voltage 19 is initialized by the time constant of the resistor 12 of a time circuit 18, a variable resistor 22 and a capacitor 20. When the magnetic recording position of a floppy disk 26 is altered from the inner to the outer peripheral surfaces the projection 29 of an arm 28 closes a time constant changeover switch 24 to shortcircuit a series circuit of a resistor 23 and the switch 24 with a series circuit of a resistor 21 and the resistor 22, thereby reducing the resistance of the time constant circuit 19. Thus, the rotation of the motor 12 is accelerated. |
