JP2000322812A - Magnetic disc drive, recovery method of magnetic head, storage medium storing restoration program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the restoration time of a magnetic head from offset when the servo position information of the magnetic head cannot be read continuously from the magnetic disc, or when possibility for inclusion of an error in the detected data is high due to the change in the floating amount of the magnetic head due to vibration impact from the outside in the magnetic disc drive. SOLUTION: In a magnetic disc drive, an observer 16 estimates a position/ velocity information of a magnetic head 23 (107b). Moreover, an impact sensor 10 detects vibration impact from the external side. Depending on the magnitude of vibration impact (101), existence or no-existence of detected error of servo information of the magnetic head (103) and magnitude of estimated error (106), any one of the estimated position/velocity information (107b) of observer 16 and detected information from the magnetic head (105) is selected with a selector 15 for calculation of the control amount of an actuator (110).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering a magnetic head from an offset due to vibration and impact in a magnetic disk drive.

[0002]

2. Description of the Related Art In a magnetic disk device for recording and reproducing information, data is recorded (written) and reproduced (read) while a magnetic head floats on a rotating magnetic disk. The position of the magnetic head is controlled using position information of the magnetic head recorded on the magnetic disk. For example, when the magnetic head deviates from the track on which data is to be recorded or reproduced (on-track) due to vibration and shock applied from the outside (off-track), the magnetic head is returned to the original position by the position information.

Specifically, the following processing is performed. If the magnetic head cannot continuously detect certain position information written on the magnetic disk, it is checked whether an external vibration or shock has acted on the magnetic disk device. If vibration and shock were applied, the position information could not be synchronized with the magnetic head position detecting means due to changes in the flying height of the magnetic head, or the magnetic head could be placed on an area where the position information was not written. It is determined that the magnetic head is moving. Then, a process for synchronizing the position information of the magnetic head written on the magnetic disk with the magnetic head position detecting means is performed. After the synchronization is established, a process of returning (returning) the magnetic head to the original position is performed based on the detected position information.

If the magnetic head in the middle of data recording has an off-track, the writing is immediately stopped to prevent data destruction due to unintended writing in an area where another data is already recorded. In. In recent years, as the capacity of magnetic disk devices has increased, track density has been improved as one method for increasing the capacity, and as a result, the track pitch has been reduced. Further, in order to improve the sensitivity of the magnetic head, the flying height of the magnetic head is reduced. For this reason, off-track of the magnetic head is extremely easily caused by external vibration and impact. In particular, the possibility that the off-track occurs at the time of writing and destroys data is increased.

Therefore, the on-track range (the area on the magnetic disk where the magnetic head is considered to be on-track) included in the position information read from the magnetic disk by the magnetic head is reduced, and the signal detected by the impact sensor is reduced. To stop writing data.
This effectively prevents the magnetic head from writing data during off-track and destroying data on the magnetic disk.

[0006]

However, in order to perform the above-described return processing of the conventional magnetic head, it takes several seconds. During that period, data cannot be written or read. This means that a discontinuity occurs in reading data, that is, reading stops unexpectedly. Therefore, when a magnetic disk is used for an audio-visual (AV) application that requires data continuity, there has been a serious problem that sound and video are interrupted.

[0007] Even if an attempt is made to suppress external vibrations and shocks so as not to cause an offset in the magnetic head, there is a limit in the demand for increasing the capacity and miniaturization of the magnetic disk drive. Therefore, it is necessary to recover the magnetic head from the offset due to the vibration and impact as quickly as possible.

[0008]

In order to solve the above-mentioned problems, a magnetic disk drive according to the present invention comprises: a magnetic disk as an information recording medium; a magnetic head for recording and reproducing information on and from the magnetic disk; Read / write means for controlling recording and reproduction of information by the magnetic head; an actuator for supporting the magnetic head; actuator driving means for driving the actuator to move the magnetic head to a predetermined position; Magnetic head position detecting means for calculating magnetic head detection position information from servo information of the magnetic head reproduced from the disk by the magnetic head, control amount calculating means for calculating a control amount for controlling the actuator, A shock sensor for detecting a vibration shock from the sensor, and a vibration shock signal from the shock sensor. A vibration / shock detecting means for detecting that the shock exceeds a predetermined threshold, wherein the control amount calculating means comprises: an observer for estimating position / speed information of the magnetic head; and a vibration / shock from the vibration / shock means. A servo signal detection error signal indicating a detection error of the servo information of the magnetic head from the magnetic head position detecting means from the detection signal and the normal position / speed information including the detected position information from the magnetic head position detecting means. And a selector for selecting any one of the estimated position / speed information from the observer as the magnetic head position / speed information used for calculating the control amount.

With this configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the time required for the magnetic head to recover from the offset can be shortened.

Further, in addition to the above configuration, the observer calculates an estimation error from the estimated position / speed information of the magnetic head and the detected position information of the magnetic head, and the selector calculates the vibration / shock and the estimated error. Is larger than each of the predetermined thresholds, it is selected to use the estimated position / speed information as the magnetic head position / speed information.

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be incorrect due to the influence of vibration and shock, the estimated position / speed information of the observer is used instead. be able to. Therefore, more reliable magnetic head position information can be obtained, and the magnetic head can be quickly returned from the offset.

In order to solve the above-mentioned problem, a method for returning a magnetic head from off-track in a magnetic disk drive according to the present invention is to extract servo information to be reproduced by the magnetic head from read / write means, and to detect a magnetic head detection position. Calculating information, calculating a control amount for controlling the drive of the actuator required to move the magnetic head to a predetermined position, and driving the actuator corresponding to the control amount, Moving the magnetic head to a predetermined position, and detecting, by using an impact sensor, that an external vibration / impact exceeds a predetermined threshold, and calculating the detected position information. Checking the detection error of the servo information, and calculating the control amount comprises: The position / speed information of the magnetic head is estimated, and if the vibration / impact exceeds a predetermined threshold, and if there is an error in the detection of the servo information, the position / speed information estimated by the observer is used as the control amount. Choose to use in the calculation of.

With such a configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the recovery time of the magnetic head from the offset can be shortened.

In addition to the above configuration, the method further comprises a step of calculating an estimation error from the estimated position / speed information of the observer and the detected position information, and correcting the estimated position / speed information. Exceeds a predetermined threshold, and
If there is no error in the detection of the servo information (104) and the estimated error exceeds a predetermined threshold, the corrected position / speed information is used as the estimated position / speed information used for calculating the control amount. Select

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be erroneous due to the impact of vibration, the estimated position / speed information of the observer can be used instead. it can. Therefore, more reliable magnetic head position information can be obtained, and the magnetic head can be quickly returned from the offset.

In order to solve the above-mentioned problems, a recording medium in which a program is recorded from an off-track of a magnetic head in a magnetic disk drive of the present invention, servo information to be reproduced by the magnetic head is taken out from read / write means, and A process of calculating head detection position information; a process of calculating a control amount for controlling driving of an actuator necessary for moving the magnetic head to a predetermined position; and the actuator corresponding to the control amount And a process of moving the magnetic head to a predetermined position, and a process of detecting that an external vibration / impact exceeds a predetermined threshold using an impact sensor. The calculating process includes a process of checking an error in detection of the servo information, and the process of calculating the control amount uses an observer. A process for estimating the position / speed information of the magnetic head, and, if the vibration / shock exceeds a predetermined threshold, if there is an error in the detection of the servo information, the estimated position / speed information of the observer is converted to the control amount. And selecting the data to be used for the calculation.

With such a configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the return time of the offset magnetic head can be shortened.

Further, in addition to the above-described configuration, a process of calculating an estimation error from the estimated position / speed information of the observer and the detected position information and correcting the estimated position / speed information; When the threshold value is exceeded and there is no error in the detection of the servo information, and when the estimated error exceeds a predetermined threshold value, the corrected estimated position is used as the estimated position / speed information used for calculating the control amount. A recording medium having a process for selecting speed information;

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be erroneous due to the impact of vibration, the estimated position / speed information of the observer can be used instead. it can. Therefore,
More reliable position information of the magnetic head can be obtained, and the return of the magnetic head from the offset can be accelerated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an actuator control block diagram according to one embodiment of the present invention. FIG. 2 is a hardware block diagram of one embodiment of the present invention. FIG. 3 shows servo information 104.
And the format of the recording area on the magnetic disk 22. FIG. 3A shows a track on the magnetic disk 22, and FIG. 3B shows a format of the servo information recording area 30. FIG. 4 is a block diagram of the observer 16. FIG. 5 is a block diagram of the vibration / shock detecting means 11. FIG. 6 is a block diagram of the selector 15. FIG. 7 is a diagram showing the correspondence between input and output of the selector 15. FIG. 8 is a flowchart of a magnetic head positioning method.

First, the configuration of hardware according to an embodiment of the present invention will be described with reference to FIG. The spindle motor 25, which is supplied with current from the spindle motor driving means 26, drives the magnetic disk 22. The magnetic head 23 for reading and writing data on the magnetic disk 22 is moved by the actuator 13 onto a predetermined track of the magnetic disk.

The read / write (R / W) means 21 uses the magnetic head 23 to read and write data on the magnetic disk 22, and at the same time the magnetic head 23 reads from the magnetic disk 22. Magnetic head 2
The servo information 104 used as the position information of No. 3 is sent to the magnetic head position detecting means 14. The magnetic head position detecting means 14 calculates the detected position of the magnetic head 23 from the servo information 104 and sends it to the control amount calculating means 20 as detected position information 105. Further, the magnetic head position detecting means 14
Sends the servo information detection error signal 103 to the control amount calculating means 20 when the servo information 104 cannot be read.

On the other hand, the shock sensor 10 sends a vibration / shock signal 100 corresponding to the vibration / shock applied from the outside to the vibration / shock detecting means 11. The vibration / shock detection means 11 outputs the vibration / shock detection signal 10 according to the magnitude of the vibration / shock signal 100.
1 is sent to the control amount calculating means 20 and at the same time, a data write inhibit signal 102 is sent to the read / write means 21. The control amount calculating means 20 calculates a control amount 110 from the detected position information 105, the servo information detection error signal 103 and the vibration / shock detection signal 101,
Send to 2. The actuator driving means 12 includes the control amount 11
A current corresponding to 0 is given to the actuator driving motor 24.

Next, the format of the servo information recording area 30 on the magnetic disk 22 will be described with reference to FIG. As shown in FIG. 3A, tracks are provided on the magnetic disk 22 on concentric circles. The magnetic disk 2
2, servo information 104 used for positioning the magnetic head 23 is written radially from the center.

The servo information recording area 30 is shown in FIG.
As shown in FIG. 7, the track consists of 31 to 34 areas. Reference numeral 31 denotes a recording area of a synchronization signal used for synchronizing detection clocks, 32 denotes a recording area of a servo mark signal used as a mark of the servo information 104, and 33 denotes a recording of a track number signal indicating a physical track position. The areas 34a, 34b, 34c and 34d are recording areas for burst signals A, B, C and D to be used for positioning the magnetic head 23, respectively. The burst signal is A,
There is a positional relationship in which the phases shift by 50% in the order of C, B, and D. The position of the magnetic head 23 is detected from the track number signal on the recording area 33 and the burst signals A, B, C, D on the recording area 34.

The configuration of the control circuit of the actuator 13 in the embodiment of the present invention will be described with reference to FIG. The control amount calculation means 20 includes an observer 16, a selector 15, a matrix distributor 17, a matrix combiner 18, and a feedback gain 19.

The observer 16 is a model of the actuator driving means 12 and the actuator 13. The control amount 110 is also input to the observer 16,
The observer 16 calculates the estimated position / speed information 107 b of the magnetic head 23 from the input control amount 110 and outputs the information to the selector 15. Here, the position / speed information refers to information including the speed and bias of the magnetic head 23 in addition to the position. Further, detection position information 105 of the magnetic head 22 detected by the magnetic head position detection means 14.
From the estimated position / speed information 107b, the estimated position / speed information 107a (hereinafter, referred to as corrected estimated position / speed information) in which the estimation error is corrected is calculated and output to the selector 15.

When the servo information 104 cannot be read, the magnetic head position detecting means 14 inputs a servo information detection error signal 103 to the selector 15. On the other hand, the vibration / shock detection means 11 outputs a vibration / shock detection signal 101 to the selector 15 according to the magnitude of the vibration / shock signal 100.

The selector 15 detects the detected position information 105, the estimated position / speed information 107b, and the corrected estimated position / speed information 1
The position / speed information 108 used for calculation of the control amount (hereinafter, referred to as control amount calculation position / speed information) in accordance with the input servo information detection error signal 103 and vibration / shock detection signal 101 from among 07a. And outputs it to the matrix distributor 17.

The matrix distributor 17 distributes the control amount calculation position / velocity information 108 into three elements: magnetic head speed information 112a, bias information 112b, and magnetic head position information 112d. Further, target position information 113 indicating the position of the magnetic head 22 input from the host system.
And the magnetic head position information 112d is calculated, and position error information 112c is calculated.

The matrix coupler 18 outputs the magnetic head speed information 1
12a, bias information 112b, position error information 112c
Are combined to generate final position / velocity information 111. The control amount 110 is obtained by multiplying the final position / speed information 111 by the feedback gain 19.

The structure of the observer 16 according to the embodiment of the present invention will be described with reference to FIG. The observer 16 includes a system matrix 43, an input matrix 40, an output matrix 42, a one-sample delay 41, and an observer gain 4
Consists of four.

The estimated position information 401 of the magnetic head is obtained by multiplying the estimated position / speed information 107b by the output matrix 42. Then, the difference between the detected position information 105 of the magnetic head from the magnetic head position detecting means 14 and the estimated position information 401 is calculated, thereby obtaining an estimation error 106.
Is obtained. Observer gain 44 for estimation error 106
To obtain the sum with the estimated position / speed information 107b, thereby obtaining the corrected estimated position / speed information 107a.

The selector 15 receives the estimated position / speed information 10
7b or the corrected estimated position / speed information 107a, based on the servo information detection error signal 103 and the vibration / shock detection signal 101, the position / speed information 109 used by the observer (hereinafter, the observer position / speed information 107a). And outputs it to the system matrix 43. By multiplying the observer position / velocity information 109 by the system matrix 43 and multiplying the control amount 110 by the input matrix 40, the position / velocity information 400 for use in the next estimation stage is obtained. Sample information). Estimated position / speed information 1
07b indicates that the one-sample delay 41 is equal to the next sample information 400.
To obtain.

The structure of the vibration / shock means 11 will be described with reference to FIG. The vibration / shock detection means 11 includes an amplification circuit 50, a low-pass filter 51, a comparator 52, and a detection unit 53.

The shock sensor 10 outputs a vibration shock signal 100 corresponding to a vibration shock from the outside to the vibration shock detecting means 11.
Output to The vibration shock signal 100 includes a radial component 100a, a tangential component 100b, and a normal component 100c on the magnetic disk surface. Each component of the vibration / shock signal 100 is amplified by the amplifier circuit 50, and the low-pass filter 5
The waveform is shaped by 1 and the comparator 52 determines whether or not a predetermined value has been exceeded, and outputs the result to the detection unit 53. If any one of the components of the vibration / shock signal 100 exceeds the predetermined value, the detection unit 53 outputs the data write inhibit signal 10.
2 is output to the read / write means 21. Also, the component 10 of the vibration / shock signal 100 in the normal direction of the surface of the magnetic disk 22
Only when 0c exceeds a predetermined value, the vibration / shock detection signal 10
1 is output to the selector 15.

The configuration of the selector 15 will be described with reference to FIGS. The normal position / speed information 600 includes the magnetic head 22 among the elements of the corrected estimated position / speed information 107b.
Are replaced in the detected position information 105.

As shown in FIG. 7, in accordance with the servo information detection error signal 103, the vibration / shock detection signal 101, and the estimation error 106 input to the selector 15, the control amount calculation position / speed information 108 and the observer position are calculated.・
What and how to select the speed information 109 will be described.

When the servo information detection error signal 103 and the vibration / shock detection signal 101 are false, the selector 15 uses the corrected estimated position / speed information as the observer position / speed information 109.
The speed information 107a is selected, and the normal position / speed information 600 is selected as the control amount calculation position / speed information.

When the servo information detection error signal 103 is true, the selector 15 generates the observer position / speed information 109 and the control amount calculation position / speed information 108 regardless of whether the vibration / shock detection signal 101 is true or false. Select the estimated position / velocity information 107b.

When the servo information detection error signal 103 is false and the vibration / shock detection signal 101 is true, first, if the estimation error 106 exceeds a predetermined value, the position for the observer
Speed information 109 and position / speed information 108 for control amount calculation
, The estimated position / velocity information 107b is selected. Next, when the estimation error 106 does not exceed the predetermined value, the corrected estimated position / speed information 107a is used as the observer position / speed information 109, and the control amount calculation position / speed information 108
And the normal position / velocity information 600 is selected.

A method of positioning the magnetic head 23 using the above configuration will be described below in steps 1 to 8. FIG. 8 shows the flow between the steps. However, step S0 shows the flow of vibration and impact detection by the impact sensor 10.

<< Step 1 >> Magnetic head position detecting means 1
4, the detected position information 10 is obtained from the track number signal of the servo information 104 and the burst signals A, B, C, and D.
Calculate 5.

<< Step 2 >> By the observer 16,
The estimated position / speed information 107b, the estimated position information 401, and the estimated error 106 are calculated. Xerr = y−Xb1 Here, Xerr is the estimation error 106, y is the detected position information 105, and Xb1 is the estimated position information 401.

<< Step 3 >> The observer 16 calculates the corrected estimated position / velocity information 107a. Xh = Xb + Lc × Xerr where Xh is the corrected estimated position / speed information 106, Xb is the estimated position / speed information 107b, and Lc is the observer gain 44.

<< Step 4 >> The selector 15 uses the position / velocity information 109 for the observer and the position / speed
Selection with the speed information 108 is performed.

1) When the servo information detection error signal 103 and the vibration / shock detection signal 101 are false, the corrected estimated position / speed information 10 is used as the observer position / speed information 109.
7a is selected as the normal position / speed information 600 as the control amount calculation position / speed information 108.

2) When the servo information detection error signal 103 is true, regardless of whether the vibration / shock detection signal 101 is true or false,
The estimated position / speed information 10 is used as the observer position / speed information 109 and the control amount calculation position / speed information 108.
7b is selected.

3) When the servo information detection error signal 103 is false and the vibration / shock detection signal 101 is true: a) When the estimation error 106 exceeds a predetermined value, the observer position / speed information 109 and the control amount The estimated position / velocity information 107b is selected together with the calculation position / velocity information 108.

B) If the estimation error 106 does not exceed the predetermined value, the corrected estimated position / speed information 107a is used as the observer position / speed information 109, and the normal position / speed information 600 is used as the control amount calculation position / speed information 108. Select

<< Step 5 >> In the control amount calculating means 20,
Target position information 113 and position / speed information 1 for control amount calculation
The difference from the magnetic head position information 112d, which is one element of 08, is calculated to calculate a position error 112c. Magnetic head speed information 112a, bias information 112b, position error 1
From 12c, final position / velocity information 111 is obtained.

<< Step 6 >> The control amount 110 is calculated in the control amount calculating means 20 and output to the actuator driving means 12. u = K × X where u is the control amount 110, K is the feedback gain 19, and X is the final position / velocity information 111. The actuator driving unit 12 drives the actuator 13 according to the input control amount 110 to move the magnetic head 23.

<< Step 7 >> In step 4, a) In step 1), it is checked whether or not the magnetic head 23 is on-track. Checking).

B) In the case of 2), the vibration / shock detection signal 10
If 1 is false, no on-track check is performed. Servo information detection error signal 103 continuously for a specified number of times or more
Occurs, a process for synchronizing the servo information recording area 30 with the magnetic head position detecting means 14 is performed.

If the vibration / shock detection signal 101 is true, the on-track check is not performed and the vibration / shock detection signal 10
Wait for 1 to be false, that is, for the vibration and shock to subside.

C) In the case of 3), when the estimation error 106 exceeds the predetermined value, the on-track check is not performed, and the vibration / shock detection signal 101 becomes false, that is, waits until the vibration / shock stops.

If the estimation error 106 does not exceed the predetermined value, an on-track check is performed.

<Step 8> The next sample information 400 is calculated in the observer 16. Xbb = Φe × Xe + Γe × u where Xbb is the next sample information 400, Φe is the system matrix 43, Xe is the observer position / velocity information 109, and 入 力 e is the input matrix 40.

The magnetic head 23 is positioned by repeating the above eight steps.

If the selector 15 in step 4 causes a vibration and an impact to make it impossible to continuously detect the servo information of the magnetic head, the estimated position of the observer
Speed information can be used instead. In addition, even when servo information can be detected continuously, it is possible to use the estimated position / velocity information as more reliable information when it can be determined that there is a high possibility of error due to the influence of vibration and impact.

Further, since the method of returning from the offset of the magnetic head in the above-described embodiment can be computer-programmed, a computer-executable recording medium can provide the method of returning a magnetic head of the present invention. It is possible. Here, the recording medium may be any of a floppy (registered trademark) disk, a CD-ROM, a DVD, a magneto-optical disk, a removable hard disk, and a data recording device including a flash memory.

[0063]

As described above, according to the present invention, even if the servo information of the magnetic head cannot be detected due to the vibration and shock, the estimated position / speed information of the observer is used instead, so that the position of the magnetic head can be reduced. Information is not interrupted. Further, even when there is a high possibility that the servo information detected due to the vibration and impact has an error, more accurate magnetic head position information can be obtained by using the estimated position / speed information. Therefore, when the magnetic head is offset due to external vibration and shock, the time required to return to the original position can be shortened.

The method for restoring a magnetic head from an offset according to the present invention can be computer-programmed. Therefore, the method of restoring the magnetic head according to the present invention can be performed using a recording medium on which the program is recorded.

[Brief description of the drawings]

FIG. 1 is an actuator control block diagram according to one embodiment of the present invention.

FIG. 2 is a hardware block diagram of one embodiment of the present invention.

FIG. 3 is a diagram showing the format of servo information 104 and its recording area 30;

FIG. 3A is a diagram showing a track and a servo information recording area 30 on a magnetic disk 22;

FIG. 3B is a diagram showing a format of servo information 104 on the magnetic disk 22;

FIG. 4 is a block diagram of an observer 16;

FIG. 5 is a block diagram of a vibration / shock detecting means 11;

FIG. 6 is a block diagram of a selector 15.

FIG. 7 is an input / output correspondence diagram of a selector 15.

FIG. 8 is a flowchart of a magnetic head positioning method according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shock sensor 11 Vibration shock detecting means 12 Actuator driving means 13 Actuator 14 Magnetic head position detecting means 15 Selector 16 Observer 17 Matrix distributor 18 Matrix coupler 19 Feedback gain 21 Read / write means 20 Control amount calculating means 22 Magnetic disk 23 Magnetic Head 24 Actuator driving motor 25 Spindle motor 26 Spindle motor driving means 30 Servo information recording area 31 Synchronous signal recording area 32 Servo mark signal recording area 33 Track number signal recording area 34a Burst signal A recording area 34b Burst signal B recording area 34c Burst signal C recording area 34d Burst signal D recording area 40 Input matrix 41 One sample delay 42 Output matrix 43 System matrix 4 4 Observer gain 50 Amplifier circuit 51 Low-pass filter 52 Comparator 53 Detector 60 Distributor 61 Coupler 62 Selector 100 Vibration shock signal 101 Vibration shock detection signal 102 Data write inhibit signal 103 Servo information detection error signal 104 Servo information 105 Detection Position information 106 Estimation error 107a Corrected estimated position / speed information 107b Estimated position / speed information 108 Position / speed information for control amount calculation 109 Observer position / speed information 110 Control amount 111 Final position / speed information 112a Magnetic head speed information 112b Bias Information 112c Position error 112d Magnetic head position information 113 Target position information 400 Next sample information 401 Estimated position information 600 Normal position / speed information S0 Flow chart of vibration / impact detection S1 Step 1 S a magnetic head position information detection error check step S2 2 S3 step 3 S4 step 4 S4a estimated position and speed information selection S4b normal position and speed selection information S5 step 5 S6 Step 6 S7 step 7 S8 step 8

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[Procedure amendment]

[Submission date] March 21, 2000 (200.3.2
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for returning a magnetic head from off-track due to vibration and impact in a magnetic disk drive.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007] Even if an attempt is made to suppress external vibrations and shocks so as not to cause off-track on the magnetic head, there is a limit in the demand for increasing the capacity and miniaturization of the magnetic disk drive. Therefore, it is necessary to return the magnetic head from off-track due to vibration and impact as quickly as possible.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the time required for the magnetic head to return from off-track can be shortened.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be incorrect due to the influence of vibration and shock, the estimated position / speed information of the observer is used instead. be able to. Thus, position information of a more reliable magnetic head is obtained, off
The magnetic head can be returned from the track quickly.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the time required for the magnetic head to return from off-track can be shortened.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

In addition to the above configuration, the method further comprises a step of calculating an estimation error from the estimated position / speed information of the observer and the detected position information, and correcting the estimated position / speed information. Exceeds a predetermined threshold, and
When there is no error in the detection of the servo information, and when the estimated error exceeds a predetermined threshold, the corrected position / speed information is used as the estimated position / speed information used for calculating the control amount.
Select speed information.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be erroneous due to the impact of vibration, the estimated position / speed information of the observer can be used instead. it can. Therefore, more reliable magnetic head position information can be obtained, and the magnetic head can be returned from off-track quickly.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head cannot be detected, the estimated position / speed information of the observer can be used, and the recovery time of the off-track magnetic head can be shortened.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

With this configuration, even when the position information of the magnetic head can be detected, if the detected position information is likely to be erroneous due to the impact of vibration, the estimated position / speed information of the observer can be used instead. it can. Therefore,
More position information of certain magnetic head is obtained, Ofutora'
Can quickly the return of the magnetic head from the click.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

The configuration of the selector 15 will be described with reference to FIGS. The normal position / speed information 600 includes the magnetic head 22 among the elements of the corrected estimated position / speed information 107a.
Are replaced in the detected position information 105.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction contents]

<< Step 7 >> In step 4, a) In case of 1), it is checked whether the magnetic head 23 is on track, and if it is off track , a process for returning from it (hereinafter, on track) Is called a check).

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction contents]

Further, the magnetic head in the above-described embodiment
Since the method of returning from off-track can be computer-programmed, a computer-readable recording medium can provide the method of restoring a magnetic head of the present invention. Here, the recording medium may be any of a floppy disk, a CD-ROM, a DVD, a magneto-optical disk, a removable hard disk, and a data recording device including a flash memory.

[Procedure amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction contents]

[0063]

As described above, according to the present invention, even if the servo information of the magnetic head cannot be detected due to the vibration and shock, the estimated position / speed information of the observer is used instead, so that the position of the magnetic head can be reduced. Information is not interrupted. Further, even when there is a high possibility that the servo information detected due to the vibration and impact has an error, more accurate magnetic head position information can be obtained by using the estimated position / speed information. Therefore, when off-track occurs in the magnetic head due to external vibration and impact, the time required to return to the original position can be shortened.

[Procedure amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0064

[Correction method] Change

[Correction contents]

The method for recovering the magnetic head from off-track according to the present invention can be computer-programmed. Therefore, the method of restoring the magnetic head according to the present invention can be performed using a recording medium on which the program is recorded. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 6, 2000 (200.7.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

Further, in addition to the above configuration, the observer calculates an estimation error from the estimated position / speed information of the magnetic head and the detected position information of the magnetic head, and the selector determines whether the servo information is detected. When there is an error
In the case where the vibration / impact exceeds the threshold value and the estimation error exceeds a predetermined threshold value , a selection is made to use the estimated position / speed information as the magnetic head position / speed information.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

In order to solve the above-mentioned problem, a method for returning a magnetic head from off-track in a magnetic disk drive according to the present invention is to extract servo information to be reproduced by the magnetic head from read / write means, and to detect a magnetic head detection position. Calculating information, calculating a control amount for controlling the drive of the actuator required to move the magnetic head to a predetermined position, and driving the actuator corresponding to the control amount, Moving the magnetic head to a predetermined position, and detecting, by using an impact sensor, that an external vibration / impact exceeds a predetermined threshold, and calculating the detected position information. Checking the detection error of the servo information, and calculating the control amount comprises: There estimate the position and speed information of the magnetic head, when the vibration impact exceeds a predetermined threshold value, or, if there is an error in the detection of said servo information,
The position / velocity information estimated by the observer is selected to be used for calculating the control amount.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014] In addition to the above structure, comprising the step of calculating the estimated error from the estimated position and velocity information of the observer and the detected position information, the vibration impact is greater than the threshold <br/> value, And when the estimation error exceeds a predetermined threshold
The, the position and velocity information used in the calculation of the control amount Te <br/>, selects the estimated position and velocity information.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

In order to solve the above-mentioned problems, a recording medium in which a program is recorded from an off-track of a magnetic head in a magnetic disk drive of the present invention, servo information to be reproduced by the magnetic head is taken out from read / write means, and A process of calculating head detection position information; a process of calculating a control amount for controlling driving of an actuator necessary for moving the magnetic head to a predetermined position; and the actuator corresponding to the control amount And a process of moving the magnetic head to a predetermined position, and a process of detecting that an external vibration / impact exceeds a predetermined threshold using an impact sensor. The calculating process includes a process of checking an error in detection of the servo information, and the process of calculating the control amount uses an observer. A process of estimating the position and speed information of the magnetic head, when the vibration impact exceeds a predetermined threshold value, or, if there is an error in the detection of said servo information,
Selecting the estimated position / velocity information of the observer to be used for the calculation of the control amount.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

[0018] In addition to the above structure, the process of calculating the estimated error from the estimated position and velocity information of the observer and the detected position information, the vibration impact exceeds said threshold value, and the estimation error is given When the threshold is exceeded,
As the position and velocity information used in the calculation of the control amount, before
And a process for selecting the estimated position / speed information.

Claims (6)

[Claims] A magnetic disk as an information recording medium; a magnetic head for recording and reproducing information on and from the magnetic disk; a read / write means for controlling recording and reproduction of information by the magnetic head; An actuator for supporting the magnetic head; an actuator driving means for driving the actuator to move the magnetic head to a predetermined position; and detecting the magnetic head from servo information of the magnetic head reproduced by the magnetic head from the magnetic disk Magnetic head position detecting means for calculating position information; control amount calculating means for calculating a control amount for controlling the actuator; an shock sensor for detecting an external vibration shock; and a vibration shock signal from the shock sensor Vibration shock detection means for detecting that the vibration shock exceeds a predetermined threshold by An observer for estimating position / velocity information of the magnetic head; a vibration / shock detection signal from the vibration / shock detection means; and servo information of the magnetic head from the magnetic head position detection means. According to the servo information detection error signal indicating the detection error of the above, it is possible to determine whether the position information is the normal position / speed information including the detected position information from the magnetic head position detecting means or the estimated position / speed information from the observer. Magnetic head position used for calculation of
A magnetic disk drive comprising a selector for selecting as speed information. 2. The method according to claim 1, wherein the observer calculates an estimation error from the estimated position / speed information of the magnetic head and the detected position information of the magnetic head. 2. The magnetic disk drive according to claim 1, wherein when the threshold value is exceeded, a selection is made to use the estimated position / speed information as the magnetic head position / speed information. 3. A step of taking out servo information to be reproduced by a magnetic head from read / write means and calculating detection position information of the magnetic head, and driving an actuator necessary to move the magnetic head to a predetermined position. Calculating a control amount for controlling; driving the actuator in accordance with the control amount to move the magnetic head to a predetermined position; and that an external vibration / impact exceeds a predetermined threshold value. Detecting the detected position information using an impact sensor; calculating the detected position information includes checking a detection error of the servo information; and calculating the control amount includes: Estimating the position / velocity information of the magnetic head using: Selecting the position / velocity information estimated by the observer to be used in the calculation of the control amount if there is an error in the detection of the servo information. . 4. The method for returning a magnetic head from off-track in a magnetic disk drive according to claim 3, wherein an estimated error is calculated from estimated position / speed information of the observer and the detected position information. Correcting the speed information; and calculating the control amount when the vibration error exceeds a predetermined threshold value and the detection of the servo information has no error. Selecting the corrected estimated position / velocity information as the estimated position / velocity information to be used for the magnetic head. 5. A process for taking out servo information to be reproduced by a magnetic head from read / write means and calculating detection position information of the magnetic head, and driving an actuator necessary for moving the magnetic head to a predetermined position. A process of calculating a control amount for controlling; a process of driving the actuator in accordance with the control amount to move the magnetic head to a predetermined position; and that an external vibration / impact exceeds a predetermined threshold value. And a process of calculating the detected position information includes a process of checking a detection error of the servo information, and a process of calculating the control amount includes an observer. A process for estimating the position / speed information of the magnetic head using the method, and detecting an error in the servo information when the vibration / impact exceeds a predetermined threshold. A process for selecting the position / speed information estimated by the observer so as to be used for the calculation of the control amount. . 6. A program for returning a magnetic head from off-track in a magnetic disk drive according to claim 5, wherein an estimated error is calculated from the estimated position / speed information of the observer and the detected position information. A process of correcting speed information; calculating the control amount when the estimated error exceeds a predetermined threshold, when the vibration / impact exceeds a predetermined threshold, and there is no error in the detection of the servo information; Selecting the corrected estimated / speed information as the estimated position / speed information to be used for the recording of the magnetic head.