Technique for controlling tracking in an optical d

专利名称：Technique for controlling tracking in an

optical disc apparatus

发明人：Kenji Kimura申请号：US06/369085申请日：19820416公开号：US04497048A公开日：19850129

摘要：In a method for detecting a tracking error of a light spot with respect to a trackrecorded spirally or concentrically on an optical video or audio disc on which a light beamemitted from a laser light source is to be focused as a light spot by an objective lens, alight flux reflected by the disc is made incident upon a photo-detector having four lightreceiving regions divided in orthogonal directions to generate four output signals, twooutput signals from two pairs of diagonally arranged regions are summed to producefirst and second sum signals, and a tracking error signal is derived by detecting a phasedifference between the first and second sum signals. In order to detect the phasedifference, the first and second sum signals are supplied to first and second band passfilters, respectively and first and second limiter circuits, respectively to produce first andsecond zero cross signals and a phase difference between the first and second zero crosssignals is detected by a phase comparator. It is possible to effect the tracking control in astable manner without being affected by amplitude variation of the first and second sumsignals and by frequency modulated components included in the first and second sumsignals.

申请人：OLYMPUS OPTICAL CO. LTD.

代理机构：Parkhurst & Oliff

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