# US 10,872,631 B1 · Magnetic disk device and servo read processing method

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- Number: US 10,872,631 B1
- Document ID: US10872631B1
- Status: Granted
- Kind: B1
- Application number: 16/800,039
- Filed: 2020-02-25
- Granted: 2020-12-22
- Earliest claimed: 2019-09-06
- Assignees: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation
- Applicants: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation
- Inventors: Naoki Tagami; Takeyori Hara; Takayuki Kawabe
- Web page: https://patentgrep.com/patent/US10872631B1

## CPC

- G11B 5/59655: {Sector, sample or burst servo format}
- G11B 5/012: Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence)
- G11B 5/5547: {"Seek" control and circuits therefor (G11B5/5556 takes precedence)}
- G11B 5/59688: {Servo signal format patterns or signal processing thereof, e.g. dual, tri, quad, burst signal patterns}
- 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

According to one embodiment, a magnetic disk device includes a disk including a first servo sector including a first preamble, a first servo mark, a first gray code, and first burst data, a head including a write head which writes data to the disk and a read head which reads data from the disk, and a controller which stops write processing, based on a write mask gate different from a first servo gate executing read processing of the first servo sector and a write gate executing the write processing to the disk.

## Claims

### Claim 1

A magnetic disk device, comprising:
a disk including a first servo sector including a first preamble, a first servo mark, a first gray code, and first burst data;
a head including a write head which writes data to the disk and a read head which reads data from the disk; and
a controller which stops write processing, based on a write mask gate different from a first servo gate executing read processing of the first servo sector and a write gate executing the write processing to the disk.

### Claim 2 (depends on 1)

The magnetic disk device of claim 1, wherein
the controller stops the write processing when the write mask gate and the write gate are asserted simultaneously.

### Claim 3 (depends on 1)

The magnetic disk device of claim 1, wherein
the controller executes servo read of the first preamble, the first servo mark, the first gray code, and the first burst data of the first servo sector by the first servo gate.

### Claim 4 (depends on 3)

The magnetic disk device of claim 3, wherein
the first servo gate includes a second servo gate to seek and read and a third servo gate to locate on a track and read.

### Claim 5 (depends on 4)

The magnetic disk device of claim 4, wherein
the controller reads the first servo sector by the third servo gate, in a second length in a circumferential direction shorter than a first length in the circumferential direction of the disk of the first servo sector in which servo read is executed by the second servo gate.

### Claim 6 (depends on 5)

The magnetic disk device of claim 5, wherein
the controller asserts the write mask gate at second timing delayed by a first time from first timing at which the third servo gate is asserted.

### Claim 7 (depends on 6)

The magnetic disk device of claim 6, wherein
the controller calculates the first time, based on a second time corresponding to a distance in the circumferential direction of the write head and the read head, a third time corresponding to degauss, a fourth time corresponding to a differential value of the first length and the second length, and a fifth time at which the write processing transitions to the servo read processing.

### Claim 8 (depends on 7)

The magnetic disk device of claim 7, wherein
the controller negates the write mask gate at fourth timing delayed by the second time from third timing at which the first servo gate is negated.

### Claim 9 (depends on 6)

The magnetic disk device of claim 6, wherein
the disk includes a second servo sector including a second preamble, a second servo mark, a second gray code, and second burst data, and
the write mask gate includes a fourth servo gate which executes servo read of the second burst data.

### Claim 10 (depends on 9)

The magnetic disk device of claim 9, wherein
the controller asserts the fourth servo gate at the second timing.

### Claim 11

A servo read processing method applied to a magnetic disk device comprising a disk including a first servo sector including a first preamble, a first servo mark, a first gray code, and first burst data, and a head including a write head which writes data to the disk and a read head which reads data from the disk,
the method comprising:
stopping write processing, based on a write mask gate different from a first servo gate executing read processing of the first servo sector and a write gate executing the write processing to the disk.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
stopping the write processing when the write mask gate and the write gate are asserted simultaneously.

### Claim 13 (depends on 11)

The method of claim 11, further comprising:
executing servo read of the first preamble, the first servo mark, the first gray code, and the first burst data of the first servo sector by the first servo gate.

### Claim 14 (depends on 13)

The method of claim 13, wherein
the first servo gate includes a second servo gate to seek and read and a third servo gate to locate on a track and read.

### Claim 15 (depends on 14)

The method of claim 14, further comprising:
reading the first servo sector by the third servo gate, in a second length in a circumferential direction shorter than a first length in the circumferential direction of the disk of the first servo sector in which servo read is executed by the second servo gate.

### Claim 16 (depends on 15)

The method of claim 15, further comprising:
asserting the write mask gate at second timing delayed by a first time from first timing at which the third servo gate is asserted.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
calculating the first time, based on a second time corresponding to a distance in the circumferential direction of the write head and the read head, a third time corresponding to degauss, a fourth time corresponding to a differential value of the first length and the second length, and a fifth time at which the write processing transitions to the servo read processing.

### Claim 18 (depends on 17)

The method of claim 17, further comprising:
negating the write mask gate at fourth timing delayed by the second time from third timing at which the first servo gate is asserted.

### Claim 19 (depends on 16)

The method of claim 16, wherein
the disk includes a second servo sector including a second preamble, a second servo mark, a second gray code, and second burst data, and
the write mask gate includes a fourth servo gate which executes servo read of the second burst data.

### Claim 20 (depends on 19)

The method of claim 19, further comprising:
asserting the fourth servo gate at the second timing.