US 6,388,963 B1 · SIGNAL GENERATION METHOD, SIGNAL GENERATION METHOD USED IN OPTICAL DISK RECORDING AND REPRODUCING APPARATUS, OPTICAL PICK-UP USING SIGNAL GENERATION METHOD, AND OPTICAL DISK RECORDING AND REPRODUCING APPARATUS HAVING THIS OPTICAL PICK-UP

Abstract

A signal generation method capable of generating a cross track signal having a predetermined phase difference from a tracking error signal even in a land and groove recording method in which a land width and a groove width are made equal, wherein a main spot is detected at a split photodetector, a first side spot is detected at a split photodetector, and a second side spot is detected at a split photodetector; a first error is calculated as an error of the optical disk in a radial direction from four detection signals detected at the photodetector, a second error is calculated as the error of two detection signals of the photodetector, a third error is calculated as the error of two detection signals of the third photodetector, and the sum of the second and third errors is subtracted from the first error to calculate a tracking error signal; and a difference between the second error and the third error is found to calculate a cross track signal having a phase shifted by 90° from the tracking error signal TE.

Claims24

Dependent claims

A signal generation method for positioning a main spot to be radiated on an optical disk and side spots of the two sides of the main spot on lands and grooves of the optical disk, detecting the reflected light of the main spot and side spots, and calculating a track error signal and a cross track signal shifted by a predetermined phase relative to the track error signal, said method comprising the steps of:

detecting the reflected light of the main spot by a first photodetector split into four sections in the track direction and tangential direction of the optical disk, detecting the reflected light of a first side spot at one side of the main spot by a second photodetector split into two sections in the track direction of the optical disk, and detecting the reflected light of a second side spot at the other side of the main spot by a third photodetector split into two sections in the track direction of the optical disk, wherein the first and second side spots are positioned a predetermined distance of ½ or less of the land pitch away from the main spot in the redial direction of the optical disk, and wherein the predetermined phase is 180 degrees or less;
and
calculating a first error as an error in the radial direction of the optical disk from four detection signals detected by the first photodetector, calculating a second error as an error of two detection signals of the second photodetector, calculating a third error as an error of two detection signals of the third photodetector, calculating the tracking error signal by subtracting from the first error the sum of the second and third errors and finding the difference between the second error and the third error to calculate the cross track signal.

A signal generation method used for an optical disk recording and reproduction apparatus for positioning a main spot to be radiated on an optical disk and side spots of the two sides of the main spot on lands and grooves of the optical disk, detecting the reflected light of the main spot and side spots, and calculating a track error signal and a cross track signal shifted by a predetermined phase relative to the track error signal, said method comprising the steps of:

detecting the reflected light of the main spot by a first photodetector split into four sections in the track direction and tangential direction of the optical disk, detecting the reflected light of a first side spot at one side of the main spot by a second photodetector split into two sections in the track direction of the optical disk, and detecting the reflected light of a second side spot at the other side of the main spot by a third photodetector split into two sections in the track direction of the optical disk, wherein the first and second side spots are positioned a predetermined distance of ½ or less of the land pitch away from the main spot in the radial direction of the optical disk, wherein the predetermined phase is 180° degrees or less;
and
calculating a first error as an error in the radial direction of the optical disk from four detection signals detected by the first photodetector, calculating a second error as an error of two detection signals of the second photodetector, calculating a third error as an error of two detection signals of the third photodetector, calculating the tracking error signal by subtracting from the first error the sum of the second and third errors, and finding the difference between the second error and the third error to calculate the cross track signal.

An optical pick-up for positioning a main spot to be radiated on an optical disk and side spots of the two sides of the main spot on lands and grooves of the optical disk, detecting the reflected light of the main spot and side spots, and calculating a track error signal and a cross track signal shifted by a predetermined phase relative to the track error signal, said optical pick-up comprising:

a first photodetector split into four sections in the direction and tangential direction of the optical disk and receiving the reflected light of the main spot,
a second photodetector split into two sections in-the track direction of the optical disk and receiving the reflected light of a first side spot at one side of the main spot,
a third photodetector split into two sections in the track direction of the optical disk and receiving the reflected light of a second side spot at the other side of the main spot,
an optical system for directing the main spot and the two side spots to the optical disk and leading the reflected light of the main spot and the side spots to the first to third photodetectors, wherein the optical system positions the side spots at the two sides of the main spot a predetermined distance of ½ or less of the land pitch away from the main spot in the radial direction of the optical disk, and wherein the predetermined phase is 180 degrees or less;
and
a signal processing means for calculating a first error as an error in the radial direction of the optical disk from four detection signals detected by the first photodetector, calculating a second error as an error of two detection signals of the second photodetector, calculating a third error as an error of two detection signals of the third photodetector, calculating the tracking error signal by subtracting from the first error the sum of the second and third errors, and finding the difference between the second error and the third error to calculate the cross track signal.

3 more elements

An optical disk recording and reproducing apparatus comprising:

an optical disk on which lands and grooves are formed adjoining each other in the radial direction;
an optical pick-up able to move relative to the optical disk in the track direction of the optical disk;
and
a control means for tracking control of the optical pick-up with respect to the optical disk in accordance with a detection signal from the optical pick-up;
the optical pick-up having:
a first photodetector split into four sections in the track direction and tangential direction of the optical disk and receiving the reflected light of the main spot,
a second photodetector split into two sections in the track direction of the optical disk and receiving the reflected light of a first side spot at one side of the main spot,
a third photodetector split into two sections in the track direction of the optical disk and receiving the reflected light of a second side spot at the other side of the main spot,
an optical system for directing the main spot and the two side spots to the optical disk and leading the reflected light of the main spot and the side spots to the first to third photodetectors, wherein the optical system positions the side spots at the two sides of the main spot a predetermined distance of ½ or less of the land pitch away from the man spot in the radial direction of the optical disk, and wherein the predetermined phase is 180 degrees or less;
and
a signal processing means for calculating a first error as an error in the radial direction of the optical disk from four detection signals detected by the first photodetector, calculating a second error as an error of two detection signals of the second photodetector, calculating a third error as an error of two detection signals of the third photodetector, calculating the tracking error signal by substring from the first error the sum of the second and third errors, and finding the difference between the second error and the third error to calculate the cross tack signal having a predetermined phase difference from the tracking error signal and
the control means using the tracking error signal and cross track signal for tracking control.

9 more elements

An optical disk recording and reproducing apparatus comprising:

an optical disk on which lands and grooves are formed adjoining each other in the radial direction;
an optical pick-up able to move relate to the optical disk in the track direction of the optical disk;
and
a control means for tracking control of the optical pick-up with respect to the optical disk in accordance with a detection sign from the optical pick-up;
the optical pick-up having:
a first photodetector split into four sections in the track direction and tangential direction of the optical disk and receiving the reflected light of the main spot,
a second photodetector split into two sections in the track direction of the optical disk and receiving the reflected light of a first side spot at one side of the main spot,
a third photodetector split into two sections in the track direction of the optical disk and receiving the reflected light of a second side spot at the other side of the main spot,
an optical system for directing the main spot and the two side spots to the optical disk and leading the reflected light of the main spot and the side spots to the first to third photodetectors, wherein the optical system positions the side spots at the two sides of the main spot a predetermined distance of ½ or less of the land pitch away from the main spot in the radial direction of the optical disk, and wherein the predetermined phase is 180 degrees or less;
and
a tracking coil,
the control means calculating a first error as an error in the radial direction of the optical disk from four detection signals detected by the first photodetector, calculating a second error as an error of two detection signals of the second photodetector, calculating a third error as an error of two detection signals of the third photodetector, calculating the tracking error signal by subtracting from the first error the sum of the second and third errors, and finding the difference between the second error and the third error to calculate the cross track signal having a predetermined phase difference from the tracking error signal and
the control means using the tracking error signal and cross track signal for tracking control.

10 more elements

Dependencies are inferred from the claim text.

Signal generation method, signal generation method used in optical disk recording and reproducing apparatus, optical pick-up using signal generation method, and optical disk recording and reproducing apparatus having this optical pick-up

Life of this patent

Signal generation method, signal generation method used in optical disk recording and reproducing apparatus, optical pick-up using signal generation method, and optical disk recording and reproducing apparatus having this optical pick-up

Life of this patent

Abstract

Claims24