| 摘要 |
PURPOSE:To obtain a clock rate error signal in a disc reproducing device by detecting a signal having the maximum or minimum pulse width out of continuous signals, and after converting said signal into the voltage proportional to the pulse width, detecting an error between the converted voltage and a reference one. CONSTITUTION:A motor 1 is rotated by starting voltage 7 and a pick-up 5 traces on a disc 2. A readout signal is supplied to monostable multivibrators 12, 13 and clears a counter 42 through an OR gate 14. The counter 42 outputs a signal proportional to a signal changing point interval just before said clearing operation. A digital comparator 47 compares the I/O values of a D type FF 43 to enter the contents of the counter 42 into the FF 43 and store the number of clocks proportional to the pulse width. A D type FF 44 inputs the maximum value counted by the counter 42 and a digital comparator 200 digitally compares the contents of the FF 44 with a previously fixed reference value. Its error output is converted by a D/A converter 49 and returned to the motor 1 so that the clock rate is fixed. |
