Magnetic disk device

Patent metadata

Field	Value
Publication number	US-12046264-B2
Application number	US-202318184399-A
Country	US
Kind code	B2
Filing date	Mar 15, 2023
Priority date	Sep 21, 2022
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

According to one embodiment, a magnetic disk device comprises a JIT seek control unit, which uses second time series data of a current indication value of a VCM that sets a slope having an absolute value smaller than an absolute value of a slope of a first time series data in at least one of a monotonically decreasing interval of an acceleration interval and a monotonically decreasing interval of a deceleration interval of a head or an operation acceleration of the head.

First claim

What is claimed is:

1. A magnetic disk device comprising:
a head that reads and writes a disk;
a command processing unit that receives and processes a command for instructing to read from and write to a target data sector of the disk;
a seek control unit that determines an operation acceleration of the head, generates a current indication value corresponding to the operation acceleration, and moves the head to a target track where the target data sector is located; and
a voice coil motor (VCM) that controls an operation of the head based on the current indication value,
wherein the seek control unit includes a JIT seek control unit that executes JIT seek control that causes the head to wait for rotation of the disk to perform read/write processing of the target data sector, and a fastest seek control unit that executes fastest seek control that does not consider wait for rotation of the disk,
the fastest seek control unit uses first time series data of a current indication value of a VCM having a monotonically decreasing interval in which an absolute value of a VCM current is within an applicable range in an acceleration interval and a deceleration interval of the head or an operation acceleration of the head, and
the JIT seek control unit uses second time series data of a current indication value of a VCM that sets a slope having an absolute value smaller than an absolute value of a slope of the first time series data in at least one of the monotonically decreasing interval of the acceleration interval and the monotonically decreasing interval of the deceleration interval of the head or an operation acceleration of the head.

2. The magnetic disk device according to claim 1 , wherein the second time series data is provided on a non-volatile memory, or parameters necessary for generating the second time series data on firmware are provided on the non-volatile memory.

3. The magnetic disk device according to claim 1 , wherein the second time series data is time series data of a current indication value of the VCM or an operation acceleration of the head including a time interval in which an average value of a first-order derivative of the current indication value of the VCM or an absolute value of the operation acceleration of the head is 0 or near.

4. The magnetic disk device according to claim 1 , wherein the seek control unit includes a head acceleration limit threshold that is a threshold for the operation acceleration of the head, determines a second operation acceleration of the head so as to set the head acceleration limit threshold as an upper limit, and generates the current indication value based on the second operation acceleration.

5. The magnetic disk device according to claim 4 , wherein the seek control unit generates a third operation acceleration obtained by smoothing the second operation acceleration using a digital filter, and generates the current indication value based on the third operation acceleration.

6. The magnetic disk device according to claim 4 , wherein the head acceleration limit threshold has at least one of a seek distance, a rotation waiting time, a power supply voltage, and a temperature as a parameter.

7. The magnetic disk device according to claim 6 , wherein a parameter of the head acceleration limit threshold is provided on firmware or a nonvolatile memory.

8. The magnetic disk device according to claim 1 , wherein the seek control unit includes a VCM current limit threshold that is a threshold for the current indication value, generates a second current indication value for the VCM so as to set the VCM current limit threshold as an upper limit, and inputs the second current indication value to the VCM.

9. The magnetic disk device according to claim 8 , wherein the seek control unit generate a third current indication value obtained by smoothing the second current indication value using a digital filter, and inputs the third current indication value to the VCM.

10. The magnetic disk device according to claim 8 , wherein the VCM current limit threshold is determined using at least one of a seek distance, a rotation waiting time, a power supply voltage, and a temperature as a parameter.

11. The magnetic disk device according to claim 8 , wherein a parameter of the VCM current limit threshold is provided in firmware or a nonvolatile memory.

12. The magnetic disk device according to claim 1 , wherein based on at least a coefficient k (0≤k<1) indicating a degree of influence of a back electromotive force, the seek control unit sets an upper limit value to a value of the current indication value for a time interval in which the back electromotive force is generated.

13. The magnetic disk device according to claim 12 , wherein the coefficient k is determined using at least one of a seek distance, a rotation waiting time, a power supply voltage, and a temperature as a parameter.

Assignees

• Toshiba Kk
• Toshiba Electronic Devices & Storage Corp

Inventors

• Sudo Daisuke

Classifications

• G11B5/5547 Primary

  "Seek" control and circuits therefor (G11B5/5556 takes precedence) · CPC title