US 6,320,831 B1Granted

Method of processing signals for optical disc device and optical disc device utilizing two split photo detectors

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsTakashi Inoue, Keiichi Kameda, Tatsuya Suzuki, Hideaki Hatanaka, Masaaki Takata

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Abstract

An object of this invention is to provide a method for processing signals for an optical disc device and an optical disc device for immediately determining the on-track state of a main beam light impinging on an optical disc including land areas on which information is recorded, said optical disc being track-formatted to have a double spiral structure. In recording or reproducing information on or from the land areas while track-controlling a first reflected light (MB) based on a second reflect light (SB1) and a third reflect light (SB2), the phases of a sum signal (SUM) and a difference signal (DIFF) between a first push-pull signal (PP1) obtained from an output from a first split photo conductor (21) and a second push-pull signal (PP2) obtained from an output from a second split photo conductor (23) are compared to determine from the mutual phase relationship which land area is providing the first reflected light (MB).

Claims4

Dependent claims

A method of processing signals for an optical disc device, in which a track format optical disc (5) has two land areas (3, 4) of a double spiral structure on which information is recorded, said land areas being arranged adjacent to each other sandwiching between a wobbling groove (1) on which wobble information is recorded by wobbling, an has non-wobbling grooves (2) arranged outside said land areas, the method comprising the steps of:

detecting a first reflected light obtained by irradiating the land areas;
using a first split photo detector (21) disposed at a first prescribed position to detect a second reflected light obtained by irradiating the wobbling groove (1) or the non-wobbling groove (2) located adjacent to one side of the land area providing the reflected light;
using a second split photo detector (23) disposed at a second prescribed position to detect a third reflected light obtained by irradiating the wobbling (1) groove or the non-wobbling groove (2) located adjacent to the other side of the land area providing the reflected light;
and
recording or reproducing information on or from the land area while executing tracking control based on the first, second, or third reflected light or on a combination of these lights, wherein
phases of a sum signal and a difference signal are compared between a first push-pull signal obtained from an output from the first split photo detector (21) and a second push-pull signal obtained from an output from the second split photo detector (23), in order to determine from the phase relationship obtained between the sum and difference signals which land area (3, 4) is providing said first reflected light.

3 more elements

An optical disc device, in which a track format optical disc (5) has two land areas (3, 4) of a double spiral structure on which information is recorded, said land areas being arranged adjacent to each other sandwiching therebetween a wobbling groove (1) on which wobble information is recorded by wobbling, and has non-wobbling grooves (2) arranged outside said land areas, said optical disc device executing:

detecting a first reflected light obtained by irradiating the land area;
using a first split photo detector (21) disposed at a first prescribed position to detect a second reflected light obtained by irradiating the wobbling groove (1) or the non-wobbling groove (2) located adjacent to one side of the land area providing the reflected light;
using a second split photo detector (23) disposed at a second prescribed position to detect a third reflected light obtained by irradiating the wobbling groove (1) or the non-wobbling groove (2) located adjacent to the other side of the land area providing the reflected light;
and
recording or reproducing information on or from the land area while executing tracking control based on the first, second, or third reflected light or on a combination of these lights,
wherein said optical disc device comprises:
signal processing means (31) for detecting a sum signal and a difference signal between a first push-pull signal obtained from an output from the first split photo detector (21) and a second push-pull signal obtained from an output from the second split photo detector (23);
and
a phase comparator (28) for comparing phases of the sum and the difference signals to determine a mutual phase relationship, in order to use a determination output from the phase comparator as land area determination information.

6 more elements

Dependencies are inferred from the claim text.