| 摘要 |
PURPOSE:To attain the reproduction of a stable disk by providing a detecting means to detect the oscillation of the prescribed frequency band of a disk at a beam irradiating position and overlapping the output signal of the detecting means to a focus servo signal. CONSTITUTION:A unidirectional microphone 11 is built in a pick-up device 1 and the vibrational sound near a disk part, to which a beam spot is irradiated, is received. After the vibrational sound is amplified by an amplifier 13, it is impressed to a band pass filter 14, and for the sound signal near 1kHz, a gain and a phase are compensated by a compensating circuit 15 and impressed to a driving amplifier 9. Thus, a focus error signal to the inherent resonance of the disk near 1kHz is generated and a focus error signal is compensated. Consequently, at the time of the disk resonance, the focus control can be executed and a beam spot can be always correctly traced on the disk surface. |
