| 摘要 |
PCT No. PCT/JP84/00465 Sec. 371 Date May 21, 1985 Sec. 102(e) Date May 21, 1985 PCT Filed Sep. 29, 1984 PCT Pub. No. WO85/01605 PCT Pub. Date Apr. 11, 1985.The present invention pertains to an improvement for a tracking servo circuit which controls the tracking of an optical pickup on an optical disc in an apparatus for reproducing a sound or image recorded on the optical disc. The present invention is characterized by the provision of a circuit for detecting modulation of an RF signal from the optical pickup caused when the optical pickup encounters a defect such as a flaw in the disc or dust adhering thereon, a circuit for detecting modulation of the RF signal caused when an impact is externally applied to the optical pickup, and an adjusting circuit which decreases the loop gain of the tracking servo circuit when the former modulation is detected and which increases the loop gain when the latter modulation is detected, whereby the responsiveness of the optical pickup is improved and track jumping prevented.
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