Magnetic disk device and control method

Patent metadata

Field	Value
Publication number	US-2016125902-A1
Application number	US-201514637008-A
Country	US
Kind code	A1
Filing date	Mar 3, 2015
Priority date	Nov 5, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

According to one embodiment, there is provided a magnetic disk device including a casing, a seek mechanism, and a controller. The seek mechanism is attached to the casing and configured to make a magnetic head seek a target track on a magnetic disk. The controller is configured to feedback-control the seek mechanism so as to reduce a reaction force acting on the casing during an acceleration period of seek by the seek mechanism.

First claim

What is claimed is:

1 . A magnetic disk device comprising:
a casing; a seek mechanism attached to the casing and configured to make a magnetic head seek a target track on a magnetic disk; and a controller configured to feedback-control the seek mechanism so as to reduce a reaction force acting on the casing during an acceleration period of seek by the seek mechanism.

2 . The magnetic disk device of claim 1 , wherein
the controller feedback-controls the seek mechanism so as to reduce a reaction force acting on the casing further during a deceleration period of seek by the seek mechanism.

3 . The magnetic disk device of claim 1 , further comprising a detecting unit configured to detect rotational acceleration acting on the casing,
wherein the controller corrects an operation amount of seek by the seek mechanism so as to reduce a reaction force corresponding to the detected rotational acceleration during the acceleration period of seek by the seek mechanism.

4 . The magnetic disk device of claim 3 , wherein the detecting unit has:
a plurality of acceleration sensors configured to detect acceleration acting on the casing respectively; and a difference unit that obtains a difference between the accelerations detected by the plurality of acceleration sensors as rotational acceleration.

5 . The magnetic disk device of claim 3 , wherein
the controller obtains the correction amount based on a feedback parameter corresponding to a transfer characteristic from the seek operation amount to the reaction force acting on the casing, and on the reaction force acting on the casing.

6 . The magnetic disk device of claim 5 , wherein
the controller determines the feedback parameter such that feedback-control is performed with a feedback gain less than 100% of the deviation with respect to a deviation of the reaction force acting on the casing from a target reaction force.

7 . The magnetic disk device of claim 3 , wherein
the controller measures each of a peak value of the operation amount of seek by the seek mechanism and a peak value of the reaction force acting on the casing, determines a feedback parameter based on the measured results, and obtains a correction amount based on the determined feedback parameter and the reaction force acting on the casing.

8 . The magnetic disk device of claim 7 , wherein
the controller determines the feedback parameter such that feedback-control is performed with a feedback gain less than 100% of the deviation with respect to a deviation of the reaction force acting on the casing from a target reaction force.

9 . The magnetic disk device of claim 3 , wherein
the controller predicts a maximum gain of a transfer characteristic from the operation amount of seek by the seek mechanism to the reaction force acting on the casing, determines a feedback parameter based on the predicting result, and obtains a correction amount for the seek operation amount based on the determined feedback parameter and the reaction force acting on the casing.

10 . The magnetic disk device of claim 9 , wherein
the controller determines the feedback parameter such that feedback-control is performed with a feedback gain less than 100% of a deviation with respect to a deviation of the reaction force acting on the casing from a target reaction force.

11 . The magnetic disk device of claim 1 , wherein
the controller further feed-forward controls the seek mechanism based on rotation vibration of the casing during a tracking period.

12 . The magnetic disk device of claim 11 , wherein
the controller is configured to be able to switch between the feedback-control and the feed-forward control.

13 . The magnetic disk device of claim 12 , further comprising a detecting unit that detects rotational acceleration acting on the casing,
wherein the controller further comprises: a filter; a feedback unit that obtains a reaction force corresponding to the rotational acceleration detected by the detecting unit to supply to an input side of the filter; a feed-forward unit that obtains a correction amount corresponding to the rotational acceleration detected by the detecting unit to supply to an output side of the filter; and a switching unit that enables the feedback unit and the filter during the seek period and enables the feed-forward unit and the filter during the tracking period.

14 . The magnetic disk device of claim 12 , wherein the controller further comprises:
a first controller that feedback-controls the seek mechanism so as to reduce a reaction force acting on the casing; a second controller that feed-forward controls the seek mechanism based on the rotation vibration of the casing; and a switching unit that enables the first controller during the seek period and enables the second controller during the tracking period.

15 . The magnetic disk device of claim 14 , wherein the controller further comprises a detecting unit that detects rotational acceleration acting on the casing,
wherein the first controller further comprises: a first filter; and a feedback unit that obtains a reaction force corresponding to the rotational acceleration detected by the detecting unit to supply to an input side of the first filter, and wherein the second controller further comprises: a second filter; and a feed-forward unit that obtains a correction amount corresponding to the rotational acceleration detected by the detecting unit to supply to an output side of the second filter.

16 . A control method for a magnetic disk device having a casing and a seek mechanism attached to the casing that makes a magnetic head seek a target track on a magnetic disk, the control method comprising:
feedback-controlling the seek mechanism so as to reduce a reaction force acting on the casing during an acceleration period of seek by the seek mechanism.

17 . The control method of claim 16 , further comprising: feedback-controlling the seek mechanism so as to reduce a reaction force acting on the casing during a deceleration period of seek by the seek mechanism.

18 . The control method of claim 16 , wherein
the feedback-controlling comprises: detecting rotational acceleration acting on the casing; and correcting an operation amount of seek by the seek mechanism so as to reduce a reaction force agreeing with the detected rotational acceleration.

19 . The control method of claim 18 , wherein
the correcting the operation amount of seek comprises obtaining the correction amount based on a feedback parameter corresponding to a transfer characteristic from the seek operation amount to the reaction force acting on the casing, and on the reaction force acting on the casing.

20 . The control method of claim 19 , wherein
the correcting the operation amount of seek comprises obtaining the correction amount using feedback parameter determined such that feedback-control is performed with a feedback gain less than 100% of a deviation with respect to a deviation of the reaction force acting on the casing from a target reaction force.

Assignees

• Toshiba Kk

Inventors

• Iwashiro Masafumi

Classifications

• G11B5/5547 Primary

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

• G11B5/5565 Primary

  system adaptation for compensation of variations of physical parameters, e.g. temperature · CPC title

• G11B5/5586

  Minimising seek noise, e.g. actuator noise · CPC title