# US 7,612,959 B2 · Method for correcting added and lost bits in a hard disk drive using error correction codes

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- Number: US 7,612,959 B2
- Document ID: US7612959B2
- Status: Granted
- Kind: B2
- Application number: 11/600,669
- Filed: 2006-11-15
- Published: 2008-05-15
- Granted: 2009-11-03
- Earliest claimed: 2006-11-15
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Yawshing Tang; Carl Xiaodong Che
- Web page: https://patentgrep.com/patent/US7612959B2

## CPC

- G11B 20/1803: {by redundancy in data representation}
- 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 hard disk drive with an encoder that writes data onto a disk in accordance with a plurality of first codes. Each code contains a plurality of digital bits. The first codes are selected so that if a bit is added or dropped during a write or read process the resulting bitstream can only be one of the selected first codes. This allows the bitstream to be accurately decoded to detect and correct for the added/dropped bit.

## Claims

### Claim 1

A hard disk drive, comprising:
a disk;
a spindle motor that rotates said disk;
a head coupled to said disk; and,
a circuit that encodes a series of bits into a plurality of first codes and writes said first codes onto said disk, said first codes having a sequence so that when one of a plurality of second codes is read back from said disk and includes an extra bit, said second code can only be one of said first codes, said first codes are derived by listing a plurality of possible codes that may be associated with said second codes, selecting a first code and then deselecting each possible code that can be associated with said first and second codes.

### Claim 2 (depends on 1)

The disk drive of claim 1, wherein said first codes are selected based on a selection assuming that each extra bit equals a preceding bit.

### Claim 3 (depends on 1)

The disk drive of claim 1, wherein said first codes each have 3 bits and each second code has 4 bits.

### Claim 4 (depends on 1)

The disk drive of claim 1, wherein said circuit includes an encoder.

### Claim 5

A hard disk drive, comprising:
a disk;
a spindle motor that rotates said disk;
a head coupled to said disk; and,
circuit means for encoding a series of bits into a plurality of first codes and writing said first codes onto said disk, said first codes having a sequence so that when one of a plurality of second codes is read back from said disk and includes an extra bit, said second code can only be one of said first codes, said first codes are derived by listing a plurality of possible codes that may be associated with said second codes, selecting a first code and then deselecting each possible code that can be associated with said first and second codes.

### Claim 6 (depends on 5)

The disk drive of claim 5, wherein said first codes are selected based on a selection assuming that each extra bit equals a preceding bit.

### Claim 7 (depends on 5)

The disk drive of claim 5, wherein said first codes each have 3 bits and each second code has 4 bits.

### Claim 8 (depends on 5)

The disk drive of claim 5, wherein said circuit includes an encoder.

### Claim 9

A method for controlling a read/write operation of a hard disk drive, comprising:
encoding a series of bits into a plurality of first codes;
writing the first codes onto a disk; and,
reading the first codes from the disk, the first codes having a sequence so that when one of a plurality of second codes is read back from the disk and includes an extra bit, the second code can only be one of the first codes, the first codes are derived by listing a plurality of possible codes that may be associated with the second codes, selecting a first code and then deselecting each possible code that can be associated with the first code.

### Claim 10 (depends on 9)

The method of claim 9, wherein the first codes are selected based on a selection assuming that each extra bit equals a preceding bit.

### Claim 11 (depends on 9)

The method of claim 9, wherein the first codes each have 3 bits and each second code has 4 bits.