# US 6,721,243 B2 · Method for detecting servo error, apparatus therefor, disk which maintains quality of servo error signal, method of controlling servo of disk recording/reproducing apparatus, method of detecting tracking error, and method of detecting tilt error

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- Number: US 6,721,243 B2
- Document ID: US6721243B2
- Status: Granted
- Kind: B2
- Application number: 10/378,904
- Filed: 2003-03-05
- Published: 2003-07-10
- Granted: 2004-04-13
- Earliest claimed: 1998-08-29
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Seong-sin Joo; In-sik Park; Byung-in Ma; Chong-sam Chung; Jang-hoon Yoo; Jung-wan Ko; Kyung-geun Lee; Joong-eon Seo
- Web page: https://patentgrep.com/patent/US6721243B2

## CPC

- G11B 7/00718: {Groove and land recording, i.e. user data recorded both in the grooves and on the lands}
- 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 7/0956: {to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc}
- G11B 7/0941: {Methods and circuits for servo gain or phase compensation during operation (for initialising servos G11B7/0945)}
- 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)

## Abstract

A method of detecting a servo error, an apparatus therefor, a disk which maintains quantity of a servo error signal, a method of controlling a servo of an apparatus for recording data on and reproducing data from a disk, a method of detecting the tracking error, and a method of detecting tilt error of the apparatus. The apparatus for recording data on and reproducing data from the disk in which a recording area is divided into sectors, each sector has a header for indicating an address, each header has a first header and a second header which are recorded to deviate from the center of the track in opposite directions, and the first header and the second header have address areas in which the addresses of sectors are recorded and synchronous signal areas in which synchronous signals for detecting the address signals recorded in the address area are recorded. As a result, it is possible for the recording/reproducing apparatus to stably control a servo therein and maintain an optimal recording/reproducing state since the apparatus for detecting the servo error correctly detects the servo error state of the disk.

## Claims

### Claim 1

A method of detecting a servo error of a recording and/or reproducing apparatus for recording data on and reproducing data from a disk in a data area of which reference patterns having a uniform size are recorded, the method comprising:
determining a first magnitude of the reference patterns recorded on at least two positions separated from each other and a second magnitude of a reproducing signal corresponding to the reference patterns; and
detecting the servo error in accordance with a ratio of the first magnitude to the second magnitude.

### Claim 2 (depends on 1)

The method of claim 1, wherein the disk is divided into sectors and each reference pattern is a synchronous signal included in a header area in which the addresses of the sectors are recorded.

### Claim 3 (depends on 1)

The method of claim 1, wherein the disk comprises a land track and a groove track and each reference pattern is a wobble signal for separating the land track from the groove track in a radial direction of the disk.

### Claim 4

A method of detecting a servo error of an apparatus for reproducing data from an optical disk in which a recording area is divided into sectors, each sector has a header for indicating an address, each header has a first header and a second header which are recorded to deviate from a center of a track in opposite directions, and the first header and the second header have address areas in which address signals of the sectors are recorded and synchronous signal areas in which synchronous signals for detecting the address signals recorded in the address areas are recorded, the method comprising:
determining a level Ivfo1 of a first synchronous signal of a reproducing signal in the first header and a level Ivfo3 of a second synchronous signal in the second header; and
detecting a servo error in accordance with a ratio of a magnitude of Ivfo1 to a magnitude of Ivfo3.

### Claim 5 (depends on 4)

The method of claim 4, wherein the magnitude ratio is (Ivfo−Ivfo3)/(Ivfo+Ivfo3).

### Claim 6 (depends on 4)

The method of claim 4, wherein the magnitude ratio is (Ivfo−Ivfo3)/Io, wherein lo is a level of a mirror signal.

### Claim 7 (depends on 4)

The method of claim 4, wherein the reproducing signal is a sum signal of radial pairs in a photodetector divided into four sections.

### Claim 8 (depends on 4)

The method of claim 4, wherein the reproducing signal is a push-pull signal RF_pp and the detected servo error is a tilt error signal.

### Claim 9 (depends on 4)

The method of claim 4, wherein the reproducing signal is a sum signal RF_sum and the detected servo error is a tracking error signal.

### Claim 10 (depends on 4)

The method of claim 4, wherein the detecting of the servo error comprises determining the magnitude ratio by averaging magnitude ratios obtained from a plurality of sectors adjacent to each other in a tangential direction.

### Claim 11 (depends on 4)

The method of claim 4, wherein the detecting of the servo error comprises determining the magnitude ratio by averaging magnitude ratios obtained from a plurality of sectors adjacent to each other in a radial direction.

### Claim 12 (depends on 4)

The method of claim 4, wherein the optical disk has a plurality of land/groove tracks, and the method further comprises inverting the magnitude ratio in each land/groove track.

### Claim 13

A method of recording data on and reproducing data from a disk in which a recording area is divided into sectors, each sector has a header comprising an address, each header has a first header and a second header recorded to deviate from the center of the track in opposite directions, and the first header and the second header have address areas in which address signals of sectors are recorded and synchronous signal areas in which synchronous signals for detecting the address signals recorded in the address areas are recorded, the method comprising:
determining a first magnitude Ivfo1 of the synchronous clock signal in the first header and a second magnitude Ivfo3 of the synchronous clock signal in the second header and
controlling a servo so that the ratio of the first magnitude Ivfo1 to the second magnitude Ivfo3 satisfies a predetermined restricted value.

### Claim 14 (depends on 13)

The method of claim 13, wherein the restricted value is ±0.1.

### Claim 15

A method of detecting a servo error of a disk, comprising:
determining a first magnitude I1 of uniformly sized reference patterns recorded on at least two positions of an area of the disk, and determining a second magnitude I2 of a reproducing signal corresponding to the reference patterns; and
detecting a servo error based on a magnitude ratio of I1 to I2.

### Claim 16 (depends on 15)

The method of claim 15, wherein the disk is divided into sectors and each reference pattern is a synchronous signal included in a header area in which addresses of the sectors are recorded.

### Claim 17 (depends on 15)

The method of claim 15, wherein the disk comprises a land track and groove track and each reference pattern is a wobble signal separating the land track from groove track.

### Claim 18 (depends on 15)

The method of claim 15, wherein the magnitude ratio is (I1−I2)/(I1+I2).

### Claim 19 (depends on 15)

The method of claim 15, wherein the magnitude ratio is (I1−I2)/Io, where Io is a level of a mirror signal.

### Claim 20 (depends on 15)

The method of claim 15, wherein the reproducing signal is a signal from sections of a photodetector divided into sections.

### Claim 21 (depends on 15)

The method of claim 15, wherein said detecting of servo error based on a magnitude ratio includes averaging magnitude ratios obtained from a plurality of sectors of the disk adjacent to each other.