# US 5,703,846 A · Optical disk tracking control method, optical disk device, and optical disk with increased recording density

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- Number: US 5,703,846 A
- Document ID: US5703846A
- Status: Granted
- Kind: A
- Application number: 08/321,619
- Filed: 1994-10-12
- Granted: 1997-12-30
- Earliest claimed: 1993-10-13
- Assignees: Hitachi, Ltd.
- Inventors: Atsushi Saito; Hisataka Sugiyama
- Web page: https://patentgrep.com/patent/US5703846A

## CPC

- G11B 7/00745: {Sectoring or header formats within a track (formats in general G11B20/12)}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- G11B 7/08529: {Methods and circuits to control the velocity of the head as it traverses the tracks}
- G11B 7/0901: {for track following only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence)}
- G11B 7/0938: {servo format, e.g. guide tracks, pilot signals}
- G11B 7/0943: {Methods and circuits for performing mathematical operations on individual detector segment outputs}
- G11B 7/133: Shape of individual detector elements
- G11B 7/1365: Separate or integrated refractive elements, e.g. wave plates
- G11B 11/10545: {interacting directly with the magnetisation on the record carrier}
- G11B 11/10584: {characterised by the form, e.g. comprising mechanical protection elements}
- G11B 7/013: for discrete information, i.e. where each information unit is stored in a distinct discrete location {, e.g. digital information formats within a data block or sector}
- G11B 7/14: specially adapted to record on, or to reproduce from, more than one track simultaneously
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

For use with an optical disk having a plurality of reference marks Mk arranged at intervals of P in the radial direction and deviant marks Hx (x=1, 2, . . . ) arranged so as to deviate in at least two different phases in the radial direction from the reference marks Mk, an optical disk tracking control method comprising the steps of: generating tracking error signals A, B, . . . with at least two different phases obtained by addition and subtraction on combinations of the light quantity signal corresponding to the reference mark Mk and the light quantity signals corresponding to the deviant marks Hx; and positioning the data tracks at intervals of P/4 or less in the radial direction based on the tracking error signals A, B, . . . .

## Claims

### Claim 1

For use with an optical disk having a plurality of reference marks Mk arranged at intervals of P in the radial direction and deviant marks H1 arranged so as to deviate by P/4 toward the outside of the radial direction from the reference marks and deviant marks H2 arranged so as to deviate by P/4 toward the inside of the radial direction from the reference marks, an optical disk tracking control method comprising the steps of:
generating a tracking error signal A from a difference between a light quantity corresponding to said deviant mark H1 and a light quantity corresponding to said reference mark Mk;
generating a tracking error signal B from a difference between the light quantity corresponding to said reference mark Mk and a light quantity corresponding to said deviant mark H2;
generating a tracking error signal C from a difference between the light quantity corresponding to said deviant mark H1 and the light quantity corresponding to said deviant mark H2;
generating a tracking error signal D from a difference between said tracking error signal A and said tracking error signal B; and
positioning a light spot on data tracks which are arranged at intervals of P/8 in the radial direction based on the tracking error signals A, B, C and D.

### Claim 2 (depends on 1)

A tracking control method according to claim 1, wherein said reference marks Mk are clock marks and said deviant marks H1 and H2 are wobble marks.

### Claim 3 (depends on 2)

A tracking control method according to claim 2, wherein a plurality of access marks are located at a same radial positions as said clock marks, wherein said light spot is positioned to the access mark in the radial direction based on said tracking error signal C.

### Claim 4 (depends on 1)

A tracking control method according to claim 1, wherein the light spot is positioned on data tracks by detecting zero-cross points of said tracking error signals A, B, C, and D.

### Claim 5 (depends on 1)

A tracking control method according to claim 1, wherein the light spot is positioned on data tracks by detecting zero-cross points of said tracking error signals A, B, C and D and sign-inverted tracking error signals -A, -B, -C, and -D.

### Claim 6

An optical disk device for reproducing data from or recording data onto an optical disk having a plurality of reference marks Mk arranged at intervals of P in the radial direction, deviant marks H2 arranged so as to deviate by P/4 toward the outside of the radial direction from the reference marks Mk, and deviant marks H2 arranged so as to deviate by P/4 toward the inside of the radial direction from said reference marks Mk, said optical disk device comprising:
a servo signal detector for generating a tracking error signal A from a difference between a light quantity corresponding to said deviant mark H1 and a light quantity corresponding to said reference mark Mk, generating a tracking error signal B from a difference between the light quantity corresponding to said reference mark Mk and a light quantity corresponding to said deviant mark H2, generating a tracking error signal C from a difference between the light quantity corresponding to said deviant mark H1 and the light quantity corresponding to said deviant mark H2, and generating a tracking error signal D from a difference between said tracking error signal A and said tracking error signal B; and
a servo controller for generating a servo control signal for positioning a light spot on data tracks which are arranged at intervals of P/8 in the radial direction based on said tracking error signals A, B, C and D.