| 摘要 |
PURPOSE:To obtain an optional linear speed, by generating a reference voltage which is proportional to the distance between the center of a disk recording medium and a pickup, producing the sawtooth wave signal which is in synchronous with the revolution of a motor, and making correspondent inclination of the sawtooth wave signal with the linear speed. CONSTITUTION:The signals are reproduced from a disk recording medium 1 through a pickup 3 attached to a mobile stage 4 which is moved by a pulse motor 5. The number of steps of the motor 5 is counted by an up-down counter 6, and the reference voltage corresponding to the count value of the counter 6 is generated 7 and fed to a comparator 12. The frequency proportional to the number of revolutions of a DC motor 2 is generated 8 and converted into the square wave generating circuit 10. Thus the sawtooth wave signal. The inclination of this sawtooth wave signal is controlled by the control signal 11. This control output is compared 12 with the reference voltage 7. The speed error signal obtained from the comparator 12 undergoes the pulse width-voltage conversion 13 and then the power amplification 14. Thus the speed of the motor 2 is controlled. As a result, a desired equilinear speed revolution is obtained. |
