JP2870127B
n pairs of light beams are applied to an optical disc (D) to form a plurality of beam spots (SP) thereon which are offset by 1/2n of a track pitch p, and n signals which are shifted p/2n in spatial phase are generated from detected output signals indicative of light beams reflected from the beam spo...
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Zusammenfassung: | n pairs of light beams are applied to an optical disc (D) to form a plurality of beam spots (SP) thereon which are offset by 1/2n of a track pitch p, and n signals which are shifted p/2n in spatial phase are generated from detected output signals indicative of light beams reflected from the beam spots (SP). These n signals are multiplied to produce a tracking control signal whose spatial period is 1/n of the track pitch p. Alternatively, the optical disc has n pairs of wobbling pits or servo pits which are offset by 1/2n of a tracking pitch p are disposed on an optical disc, and the n pairs of servo pits are scanned by a light beam to produce n signals that are shifted p/2n in spatial phase. The tracking control method is effective to effect tracking control on an optical (D) disc whose recording tracks are arragnged at a high density that exceeds the spatial cutoff frequency of an optical system of conventional nature used with the tracking control method. |
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