CONTROL METHOD FOR FOCUS AND TRACKING IN PICKUP APPARATUS

WIPO Patent Application WO2003079338

A3

Provided is a focus and tracking control method for an optical pick-up apparatus which is used for recording and reproduction of a small-sized optical disc and which can carry out stable focus control and stable tracking control. A focus control method for an optical pick-up apparatus comprising a light source (61), an objective lens (39), a light receiving (47) means having divided four light receiving zones and a polarizing means (71) having divided for lattice zones, characterized in that when the reflected light beam is incident upon the four light receiving zones by way of the four lattice zones, focus control is carried out in accordance with a difference signal between the groups, in the radial direction, of the four light receiving zones which are divided into two groups in the radial direction by the division line in parallel with the tangential direction, respectively through the four lattice zones which are divided into two groups in the tangential direction by a division line in parallel with the radial direction. Further, the tracking control for the pick-up apparatus is characterized in that tracking control is carried out in accordance with a difference signal between two groups in the tangential direction.

YOSHINAKA HIDEKI
HORINOUCHI SHOGO
ISHIBASHI SHIN
FURUKAWA FUMINOBU

PCT/JP2003/003356

April 22, 2004

March 19, 2003

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MATSUSHITA ELECTRIC IND CO LTD (JP)

G11B7/09; G11B7/135; G11B7/12; G11B7/22; G11B11/105; (IPC1-7): G11B7/09; G11B7/00

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US4533826A	1985-08-06
US20010046195A1	2001-11-29
US6512732B1	2003-01-28
US5648951A	1997-07-15

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