| 摘要 |
PURPOSE:To enable the sampling at a high speed and at the same time to eliminate the misretrieval of information, by increasing and decreasing the time interval at a sampling point at the inner and outer circumference sides of a disk after setting a constant scanning speed when reading out by the scanning of a pickup prior to a reproduction. CONSTITUTION:An optical pickup 7 is scanned prior to a reproduction, and the index signal is read with the intermittent sampling. In such a case, the DC voltage 13 is applied across a linear potentiometer 12 and then applied to a voltage controloscillator 14 as the control voltage. Then the pulse signals of a low and high frequency are oscillated when the pickup 7 is positioned at the inner and outer circumference parts of a disk 4 respectively. This pulse signal is divided by a frequency dividing circuit 15 and supplied to a tracking servo circuit 17 as the ON/OFF signals. The circuit 17 uses the output signal 18 of the pickup 7 as an input and flows a current to a tracking actuator 19 to move the pickup 7. |
