| 摘要 |
PURPOSE:To change the reproducing speed of a CD only with the operation of a switch or a volume by varying a self running frequency of a VCO of a PLL circuit, an oscillated frequency of a master clock generator by the switch of the volume of a speed selection circuit. CONSTITUTION:In turning a switch of a speed selection circuit 20 to the position (b), the switch of the PLL circuit 51 and the switch of the master clock generator 71 are turned respectively to the position (b) and a CD 1 is reproduced by the same fequency and the same speed as those of a conventional player. In turning the switch of the circuit 20 to the position (a), the switch of the PLL circuit 51 and the switch of the master clock generator 71 are turned respectively to the position (a), and the clock frequency is doubled. Since a closed loop comprising a phase comparator 8, a motor servo circuit 9, a motor 10, the CD 1, a pickup 2, a waveform shaping circuit 4 and the PLL circuit 51 constitutes a PLL, the clock component of an EFM signal read from the pickup 2 has a double frequency. Thus, the EFM signal is reproduced by the double speed and the CD is reproduced by a double speed.
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