| 摘要 |
<p>PURPOSE:To reduce the power consumption by providing a sample-hold circuit which holds the tracking error signal of a tracking control circuit and a circuit which cuts off a circuit bias voltage other than a logic circuit which outputs at least sampling pulses. CONSTITUTION:A detection signal 26 obtained by a tracking area detection part T is used to control 1st - 6th transistors TR1 - TR6 and an 8th transistor TR8 for controlling bias voltages of a regenerative amplifier 1, a low-pass filter circuit 2, an envelope detector 3, a 1st sample-hold circuit 4, a subtracter 8, an equalizer circuit 5, and a zero-cross comparator 6. Then when the detection signal 26 is high, namely, when a head traces a part other than a tracking area, a 10th TR10 is turned on the ground a source voltage Vcc from a 11th TR11 and the TR1 - TR6 and TR8 turn off to cut off the bias voltages. Consequently, the power consumption is reducible and the life of a battery is prolonged.</p> |
