| 摘要 |
PURPOSE:To always keep the relative speed constant between the signal conversion unit and disc, by detecting the electric signal in response to the relative speed between the disc shape recording media and the signal conversion unit, comparing the detected signal with the reference signal, and controlling the rotary speed of the drive unit in response to the difference signal. CONSTITUTION:The band wires 3a, 3b are provided at the back of the turn table 1. When the turn table 1 turns a certain speed, since the band wires 3a, 3b passes in front of the detectors 7a, 7b, detection pulse is obtained at the detectors 7a, 7b, and the time difference of this pulse is proportional to the moving speed of the table 1. The monostable multivibrator 10 is triggered with this pulse, triangle wave (d) is produced at the triangle wave formation circuit 11, it is held at the sample hold circuit 12, the voltage (e) in hold and the reference voltage of the reference power supply 13 are compares at the comparison circuit 14, the output of the comparison cicuit 14 in response to the difference of the both voltage is fed to the motor 2 via the compensation circuit 15, and conrol is made until the both voltages are in agreement for the revolution of the motor 2. |
