# US 6,724,553 B2 · Method and apparatus for generating the optimum read timing for read and write offset of a magneto resistive head

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- Number: US 6,724,553 B2
- Document ID: US6724553B2
- Status: Granted
- Kind: B2
- Application number: 10/037,783
- Filed: 2001-10-22
- Published: 2002-09-26
- Granted: 2004-04-20
- Earliest claimed: 2001-03-26
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Jong Yun Yun; Kang Seok Lee; Sang Hoon Chu; Gyu Tack Kim
- Web page: https://patentgrep.com/patent/US6724553B2

## CPC

- G11B 5/4886: {relative to rotating disc}
- G11B 5/012: Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence)
- G11B 5/59627: {Aligning for runout, eccentricity or offset compensation (G11B5/5534, G11B5/59677, G11B5/59688 take precedence)}
- G11B 5/59683: {for magnetoresistive heads}
- G11B 27/3027: {used signal is digitally coded}
- G11B 2005/0016: {of magnetoresistive transducers}
- G11B 2220/20: Disc-shaped record carriers
- 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 for writing and reading data in a hard disk drive and compensating for an offset between a write element and a read element of a head. The method determines an offset time by determining the difference between a desired sync byte position and an actual sync byte position located between a preamble and a data sector of the disk. The difference corresponds to the offset between the read and write elements. The offset time is subtracted from the normal time for enabling the read gate of a disk drive pre-amplifier.

## Claims

### Claim 1

A hard disk drive, comprising:
a disk;
a spindle motor coupled to said disk;
a head coupled to said disk, said head having a read element that is separated from a write element by an offset; and,
an electrical circuit that enables said read element as a function of the offset.

### Claim 2 (depends on 1)

The disk drive of claim 1, wherein said disk includes a sync byte, the offset is related to a difference between a desired sync byte location and an actual sync byte location.

### Claim 3 (depends on 2)

The disk drive of claim 2, wherein the sync byte location is measured from a sector signal.

### Claim 4 (depends on 2)

The disk drive of claim 2, wherein the sync byte location is measured from a sync address mark located on said disk.

### Claim 5 (depends on 1)

The disk drive of claim 1, wherein said electrical circuit includes a pre-amplifier circuit connected to said head, a read/write channel connected to said pre-amplifier circuit and a controller connected to said read/write channel and said pre-amplifier, said pre-amplifier circuit having a read gate coupled to said read element of said head.

### Claim 6 (depends on 1)

The disk drive of claim 1, wherein the information relating to the offset is stored on said disk.

### Claim 7 (depends on 2)

The disk drive of claim 2, wherein said disk includes a data sector and a preamble to said data sector, said sync byte being located between said data sector and said preamble.

### Claim 8

A hard disk drive, comprising:
a disk that has a sync address mark, a data sector, a preamble to said data sector, and a sync byte located between said preamble and said data sector;
a spindle motor coupled to said disk;
a head coupled to said disk, said head having a read element that is separated from a write element by an offset;
a pre-amplifier circuit connected to said head, said pre-amplifier circuit having a read gate coupled to said read element;
a read/write channel circuit connected to said pre-amplifier circuit; and,
a controller connected to read/write channel circuit and said pre-amplifier circuit, said controller provides a read gate signal to said read gate to enable said read element, a timing of said read gate signal being a function of the offset.

### Claim 9 (depends on 8)

The disk drive of claim 8, wherein the offset is determined from a desired sync byte location and an actual sync byte location.

### Claim 10 (depends on 9)

The disk drive of claim 9, wherein the actual sync byte is measured from the sync address mark.

### Claim 11 (depends on 9)

The disk drive of claim 9, wherein the actual sync byte is measured from a sector signal.

### Claim 12 (depends on 11)

The disk drive of claim 11, wherein the read gate signal is generated in accordance with a difference between a non-offset time of the read gate signal and the offset time.

### Claim 13

A hard disk drive, comprising:
a disk;
a spindle motor coupled to said disk;
a head coupled to said disk, said head having a read element that is separated from a write element by an offset; and,
circuit means for enabling said read element as a function of the offset.

### Claim 14 (depends on 13)

The disk drive of claim 13, wherein said disk includes a sync byte, the offset is related to a difference between a desired sync byte location and an actual sync byte location.

### Claim 15 (depends on 14)

The disk drive of claim 14, wherein the sync byte location is measured from a sector signal.

### Claim 16 (depends on 14)

The disk drive of claim 14, wherein the sync byte location is measured from a sync address mark located on said disk.

### Claim 17 (depends on 13)

The disk drive of claim 13, wherein said circuit means includes a pre-amplifier circuit connected to said head, a read/write channel connected to said pre-amplifier circuit and a controller connected to said read/write channel and said pre-amplifier, said pre-amplifier circuit having a read gate coupled to said read element of said head.

### Claim 18 (depends on 13)

The disk drive of claim 13, wherein the information relating to the offset is stored on said disk.

### Claim 19 (depends on 14)

The disk drive of claim 14, wherein said disk includes a data sector and a preamble to said data sector, said sync byte being located between said data sector and said preamble.

### Claim 20

A hard disk drive, comprising:
a disk that has a sync address mark, a data sector, a preamble to said data sector, and a sync byte located between said preamble and said data sector;
a spindle motor coupled to said disk;
a head coupled to said disk, said head having a read element that is separated from a write element by an offset;
a pre-amplifier circuit connected to said head, said pre-amplifier circuit having a read gate coupled to said read element;
a read/write channel circuit connected to said pre-amplifier circuit; and,
controller means for providing a read gate signal to said read gate to enable said read element, a timing of said read gate signal being a function of the offset.

### Claim 21 (depends on 20)

The disk drive of claim 20, wherein an offset time is determined from a desired sync byte location and an actual sync byte location.

### Claim 22 (depends on 21)

The disk drive of claim 21, wherein the actual sync byte is measured from the sync address mark.

### Claim 23 (depends on 21)

The disk drive of claim 21, wherein the actual sync byte is measured from a sector signal.

### Claim 24 (depends on 21)

The disk drive of claim 21, wherein the read gate signal is generated in accordance with a difference between a non-offset time of the read gate signal and the offset time.

### Claim 25

A method for enabling a read gate of a hard disk drive, comprising:
reading a sync address mark of a disk with a head that has a read element offset from a write element;
generating a sector signal; and,
enabling a read gate signal at a time that is a function of the offset.

### Claim 26

A method to determine an offset between a read element and a write element of a hard disk drive, comprising:
determining a desired sync byte location on a disk;
reading a disk with a head that has a read element;
determining an actual sync byte location of the disk; and,
generating offset information as a difference between the desired and actual sync byte locations.

### Claim 27 (depends on 26)

The method of claim 26, further comprising storing the offset information onto the disk.

### Claim 28 (depends on 26)

The method of claim 26, wherein the actual sync byte position is measured from a sync address mark.

### Claim 29 (depends on 26)

The method of claim 26, wherein the actual sync byte position is measured from a sector signal.

### Claim 30 (depends on 26)

The method of claim 26, wherein the sync byte is located between a data sector and a preamble of said data sector.

### Claim 31 (depends on 26)

The method of claim 26, further comprising using the offset information to enable a read gate.

### Claim 32

A circuit that controls a read/write operation of a data storage device that has a read element and a write element that are physically offset from each other, comprising:
a controller that generates a periodic timing reference signal, a read gate signal that precedes in time said periodic timing reference signal and indicates a start of a read operation, and a write gate signal that is subsequent in time to said periodic timing reference signal by an offset duration and indicates a start of a write operation.

### Claim 33 (depends on 32)

The circuit according to a claim 32, wherein said offset duration corresponds to said physical offset between said read element and said write element.

### Claim 34 (depends on 32)

The circuit according to claim 32, wherein said controller further generates a write gate signal that is subsequent in time to said periodic timing reference signal and indicates a start of a write operation.

### Claim 35 (depends on 32)

The circuit of claim 32, wherein said periodic timing reference signal is a SECTOR signal.

### Claim 36

A data storage device, comprising:
a storage medium;
a head coupled to said storage medium, said head having a read element that is physically offset from a write element;
a controller that generates a periodic timing reference signal, a read gate signal that precedes in time said periodic timing reference signal and indicates a start of a read operation, and a write gate signal that is subsequent in time to said periodic timing reference signal by an offset duration and indicates a start of a write operation.

### Claim 37 (depends on 36)

The data storage device according to claim 36, wherein said offset duration corresponding to said physical offset between said read element and said write element.

### Claim 38 (depends on 36)

The data storage device of claim 36, wherein said periodic timing reference signal is a SECTOR signal.

### Claim 39

A method for controlling the operation of a data storage device that has a read element physically offset from a write element, comprising:
generating a write signal that is subsequent in time to a first periodic timing reference signal to initiate a write operation through the write element; and,
generating a read gate signal that precedes in time a second periodic timing reference signal to initiate a read operation through the read element.

### Claim 40 (depends on 39)

The method of claim 39, wherein the first and second periodic timing reference signals are SECTOR signals.

### Claim 41

A circuit that controls a read/write operation of a data storage device that has a read element and a write element that are physically offset from each other, comprising:
a controller that generates a periodic timing reference signal, and a read gate signal that indicates a start of a read operation, said read gate signal being offset in time from the periodic timing reference signal by a duration that corresponds to the physical offset between the read element and the write element.

### Claim 42 (depends on 41)

The circuit of claim 41, wherein said periodic timing reference signal is a SECTOR signal.

### Claim 43

A method for controlling the read/write operation of a data storage device that has a read element and a write element that are physically offset from each other, comprising:
generating a write signal that is subsequent in time to a first periodic timing reference signal by an offset duration to initiate a write operation through the write element; and,
generating a read gate signal that precedes in time a second periodic timing reference signal to initiate a read operation through the read element.

### Claim 44 (depends on 43)

The method of claim 43, wherein the first and second periodic timing reference signals are SECTOR signals.

### Claim 45

A method of compensating for a physical offset between a read element and a write element of a data storage device, comprising:
writing a data pattern onto a storage medium, the data pattern including a preamble portion that has a start point;
determining a time duration between the start point of the preamble and a periodic timing reference signal; and,
offsetting at least one of a read gate signal and a write gate signal from said periodic timing reference signal by said determined time duration, said read gate signal indicating a start of a read operation, said write gate signal indicating a start of a write operation.

### Claim 46 (depends on 45)

The method of claim 45, wherein the time duration is stored onto the storage medium.

### Claim 47 (depends on 45)

The method of claim 45, wherein said time duration is determined by determining a time length of said preamble portion, determining a rear time duration, said rear time duration being a time difference between said periodic timing reference signal and an end of said preamble portion, and subtracting said rear time duration from said time length to arrive at said time duration.