JP2000322848A - Magnetic disc device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic disc device using a composite magnetic head having a high transfer rate of continuous data by putting a playback head on track at a high accuracy in playback. SOLUTION: A magnetic head offset measuring unit 6 measures at a high accuracy the head offset value i.e., the position difference between a playback head and a recording head in a radial direction of a magnetic disc 1 of a composite magnetic head 2. The measured offset value is previously stored in a magnetic head offset memory 7, and a magnetic head target position corrector 8 controls a positioning controller 5, based on the head offset value, to correct a target position. This makes the playback head follow up at a high accuracy information data recorded on target tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a magnetic disk drive.
In particular, the write head and read head
The present invention relates to a magnetic disk device provided on a head slider. [Prior art] In recent years, with the development of multimedia,
High-speed recording of video information, audio information, text information, etc.
A high-density magnetic disk drive for playback is required.
You. [0003] As the density of magnetic disk devices increases,
MR head or GMR applying the magnetoresistance effect
The head is used as the reproducing head, and the inductive head is used as the recording head.
Is used. The above two types
The head is mounted on the same magnetic head slider,
Type magnetic head. A head positioning mechanism for a magnetic disk drive and
Therefore, there is a demand for miniaturization and high speed, and
In the disk device, the influence of inertia can be reduced
A rotary actuator is used. [0005] Magnets with rotary actuators
In a disk drive, the magnetic head is
The trajectory of the magnetic head when accessing the
You. Therefore, from the inner circumference to the outer circumference of the magnetic disk,
What is the center line of the magnetic head slider and the tangent of the recording track?
Intersect at different angles for each track without being parallel
You. This angle is called the yaw angle. With this yaw angle,
On-track head on servo track of magnetic disk
(Be sure that the head is positioned at the correct position on the track.
), Off-track (head
Is not positioned correctly on the track)
Occurs. Position between the center of the recording head and the center of the reproducing head
Misalignment, strictly speaking, the magnetic
The deviation between the center positions is referred to as “head offset”. In a general magnetic disk drive, at the time of recording,
The data recorded on the servo track by the MR head
Detects the servo signal that has been
Move the MR head to the servo track on-track
And then use the inductive head, which is the recording head,
Write to magnetic disk. If there is a head offset,
Make the MR head on-track on the servo track,
When a data signal is reproduced by the R head, the MR head
Data signal on magnetic disk written by inductive head
Not located at the center of the data track (data track)
become. Therefore, the data signal cannot be reproduced accurately. Place
In some cases, a retry operation, which is a repetition of the playback operation,
Required, adversely affecting the transfer rate of continuous data. When the yaw angle is large, the MR head is supported.
Inductive head with on-track at the center of the robot track
At the center of the recorded data track during playback.
Try to make the MR head on-track
Incorrect detection of track number and sector number by offset
May be affected. Further, as the yaw angle increases, the head
Larger offset and reduced effective track width during playback
As a result, the level of the reproduced signal decreases. Also magnetic head protrusion
Yaw angle to the rotational tangent of the magnetic disk in the direction of the plane
Occurs. Therefore, the smooth rotation of the magnetic disk
Laminar airflow near the surface tangential to the track
Is reduced relative to the slider. This allows
The lift of the flying magnetic head slider is reduced and it rises
Height decreases. In order to avoid the above problems, the yaw angle should be at most 1
It is desirable to keep the angle between 5 degrees and 20 degrees.
And the outer circumference is designed to be substantially equal. As described above, in the composite type magnetic head, M
R head reproducing head and inductive head recording head
Have different mechanical centers and magnetic centers. That
Especially in magnetic disk drives with narrow track pitch
Is the magnetic center of each of the MR head and the inductive head
The head offset expressed by the distance between cannot be ignored
This is a major factor in performance degradation. A magnetic disk using a conventional magnetic head of this type is used.
In the disk device, the following
The countermeasures shown in the conventional example are taken. As a first conventional example, Japanese Patent Application Laid-Open No. Hei.
No. 75, position displacement compensation method and magnetic disk drive
Will be described with reference to FIG. Referring to FIG. 10, an external position reference sensor 34 is provided.
Is an actuator that controls the rotary actuator 33
The position information is given to the servo control circuit 35, and the magnetic head 30
Control the position of. The writing circuit 37 includes the recording head 3
2 to the first set of servos on the magnetic disk 29.
Write information. Next, the read head electronics 38
The first set of servo information signals read by the read head 31
The position information is processed and stored in the actuator servo control circuit 35.
To control the position of the magnetic head 30. This first set
At the position controlled by the servo information signal
The embedding circuit 37 supplies a signal to the recording head 32 to
The second set of servo information is written to the disk 29. Thus, two sets of servo information are stored on a magnetic disk.
By writing to the mark 29, the center of the data track is
Do not match the center of the servo track
I can do it. In this state, the recording head 32 is
When positioned at the center of the track, the read head 31
It will be positioned at the center of the servo track. You
That is, when writing data, the reproducing head 31 is
Positioning and recording at the write position of the first set of servo information
The head 32 transfers the data on the second set of servo information tracks.
Write on the data track. Write in this way
The two sets of servo information obtained are recorded on each track,
The magnetic disk is moved a distance equal to the misalignment with the recording head.
They are separated in the radial direction of the disc. Next, as a second conventional example, Japanese Patent Laid-Open No. 7-32
No. 6032, with reference to FIG.
It will be described with reference to FIG. In FIG. 11, data is recorded on a magnetic disk 64.
A read head 67 for reproducing the read data, and a magnetic disk.
The write head 68 that records data on the
Are mounted on the carriage 69 with a distance.
The positioning operation of the head of the carriage 69 is positioning control.
Controlled by the circuit 17. Innermost circumference of magnetic disk 64
Track 65 and the outermost track 66
Write head 68 at the center of tracks 65 and 66, respectively
When positioned, the center of the read head 67 and the track 65
And the amount of deviation from the center of each track 66 is YI,
YO. Also, the carriage 69, the track 65 and
ΘI, the angle between each tangent of the
θO. The off-track amount measuring circuit 14
From the output of the read head received from the control circuit 17,
The displacement amounts YI and YO and the angles θI and θO are measured, and the distance L
2 is calculated. The position of the head is determined based on the distance L2.
The correction amount Y for correction is tracked by the correction amount calculation circuit 16.
Calculated for each work. In the above configuration, the positioning control circuit 1
7 is based on a command from the off-track amount measuring circuit 14
Write head 68 is offset on a particular track.
Control to form a servo pattern. Offset offset
The robot pattern is a track to which the write head 68 normally writes.
1/2 track tracks on the outer and inner
Servo data for positioning written staggered
It is. Therefore, the above two offset servo patterns
The centers of the write heads are the centers of the write heads 68, respectively. book
Since the embedded data position is treated as a servo track,
The center between the two offset servo patterns is the data
It is also the center of the rack. The read head 67
By performing positioning based on the set servo pattern,
It is possible to measure the deviation amounts YI, YO and the angles θI, θO.
it can. Measured deviation amounts YI, YO and angles θI, θO
As a result, the read head 67 and the write head 68 are
Is calculated. [0018]        L2 = (YO-YI) / (tanθO-tanθI) (1) The head offset amount Y can be calculated by the equation (2).
Wear. [0020] Y = L2 · tanθ (2) Here, as a function of the position of the carriage 69,
All tan θ can be approximated. Therefore, write the value of tanθ.
There is no need to remember, use the value calculated by the approximate expression
Thus, the actual correction amount is calculated. This correction amount and correction formula
Is stored, and the correction amount calculation circuit 16 calculates the correction amount Y
Is calculated and output to the positioning control circuit 17, and the carriage
Control the positioning operation of the magnetic head
Is going. [0022] SUMMARY OF THE INVENTION In the first prior art,
The correction amount is not calculated for each rack. Also a magnetoresistive element
Between the mechanical center and magnetic center peculiar to the read head using
The amount of deviation may vary depending on variations in the manufacturing of the read head.
Although it differs for each read head, a structure that can deal with this point
I haven't made it. Therefore, a narrow track pitch (high track
Disk density), retry operation
Magnetic recording, such as an increase in
A reduction in the performance of the disk device cannot be avoided. Also,
In the second conventional example, the position is determined by an offset servo pattern.
Write the offset servo pattern
Of head position and head offset amount.
And that errors may occur due to noise, etc.
Not. Also, the innermost circumference and the outermost circumference of the magnetic disk
The interval that is the head offset amount only for the track of
To measure L2, if there is an error in either, measure
A large error occurs in the head offset amount. For this reason
In a magnetic disk drive with a high track density,
Retry operation occurs and the transfer speed of continuous data decreases.
Cause. Reduce the number of retry operations
In order to increase the data transfer speed, high accuracy offset
There is a problem that it is necessary to measure the amount of data. Variation of position when writing measurement pattern
Off using part of the servo pattern to eliminate keys
There is also a method of performing set measurement. However, when measuring
Has the problem that it cannot be applied. The present invention
Reducing the number of retry operations for combined magnetic heads
Magnetic disk that can increase the transfer rate of continuous data
It is intended to provide a device. [0024] SUMMARY OF THE INVENTION A magnetic disk drive according to the present invention.
The recording head and the recording head for recording data on the magnetic disk
Having playback head for playing back recorded data
Type magnetic head. The composite type magnetic head
Is held by the magnetic head slider and is
To the target track. The positioning controller
Written on the magnetic disk, the magnetic head
Target track based on the servo information
The position error signal indicating the position mismatch with the magnetic head
The positioning operation of the positioning mechanism is controlled by the controller. Further, the magnetic head offset measuring means includes:
Positions of the reproducing head and the recording head on the magnetic head
The radial direction of the magnetic disk caused by the relationship
Of the difference between the read head position and the write head position
Measure the offset. The measured head offset
Record the offset amount in the magnetic head offset storage means.
Good. The playback head was recorded on the target track during playback.
When following information data, the magnetic head offset
Based on the head offset amount read from the
Then, the correction generated by the magnetic head target position correcting means is performed.
Sends a positive signal to the positioning control unit to position the magnetic head.
Correct the mark position. With this configuration, a composite magnetic head can be used.
The magnetic head of each track of the recording head and read head
Can be measured with high accuracy.
During playback, the playback is centered on the written data track.
To accurately on-track the MR head
Becomes possible. Due to this, data playback error during playback
It is possible to reduce the occurrence of retry operation due to
To reduce the continuous data transfer rate.
A disk device can be realized. Further, the magnetic head offset measuring means
Is the servo pattern of the offset measurement signal on the magnetic disk.
Write a measurement pattern to write turns with a recording head
Means, head positioning mechanism and head positioning control
While moving the magnetic head slightly by the
Measure the position where the output is maximum to determine the offset amount
Offset amount measuring means, and when writing the measurement signal
Write again depending on the size of the position error
It has a position error management unit at the time of pattern writing. Said e
The offset amount measuring means includes a reproduction signal output measuring means and a magnetic head.
Head fine movement means for moving the head a minute distance, the head
Position of magnetic head moved and positioned by fine movement means
Playback signal that averages the level of the playback signal measured for each unit
Signal averaging means, a magnetic head
Reproduction output maximum value position detecting means for detecting the position, and writing
The reproduction signal level is measured by the position error at the time of
Servo wedge for selecting the magnetic disk servo wedge
Edge selection means. The reproduction signal averaging means,
Average the playback signal levels of multiple servo wedges
Measurement wedge averaging means, for at least three measurements
Mean for averaging, measured value averaging,
Calculation of measurement position averaging means and measurement value averaging means
A means for eliminating sudden disturbances except for the maximum and minimum values
Have. Magnetic head offset measuring means of this configuration
Accordingly, it is possible to prevent the error from being enlarged due to the sudden disturbance.
Further, when the head is moved a minute distance by the head fine movement means,
In addition, the playback signal level can be adjusted at multiple servo wedges.
Measured, averaged multiple measured values, and
Measurement of the magnetic head offset amount in the magnetic head with high accuracy
It becomes possible. As a result, the data playback error
Error retry operation
It is possible to prevent a decrease in the continuous data transfer speed
A magnetic disk device can be realized. [0029] DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic disk drive of the present invention
DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment will be described with reference to FIGS.
I do. << Embodiment 1 >> A magnetic disk drive according to Embodiment 1 of the present invention is described.
The description will be made with reference to FIGS. FIG. 1 shows the present invention.
Showing the configuration of the magnetic disk drive in Embodiment 1 of the present invention.
FIG. In FIG. 1, on the surface of the magnetic disk 1,
The composite magnetic head 2 is supported by the magnetic head slider 3.
Is held. The magnetic head slider 3 is moved through the arm 3A.
And is attached to the positioning mechanism 4. Positioning
The positioning operation of the mechanism unit 4 is controlled by the positioning control unit 5.
Is done. The magnetic head offset measuring unit 6 measures the pattern
The writing unit 6-1, the offset amount measuring unit 6-2, and the
A turn writing position error management unit 6-3 is provided.
Pattern writing position of magnetic head offset measuring unit 6
The output of the magnetic head 2 is input to the placement error management unit 6-3.
You. The output of the measurement pattern writing unit 6-1 is a magnetic head
2 is input. Output of magnetic head offset measuring unit 6
The end is connected to the input end of the magnetic head offset storage unit 7.
The output end of the magnetic head offset recording unit 7 is a magnetic head.
Connected to the input end of the target position correcting unit 8. Magnetic
The output end of the load target position correction unit 8 is the input end of the positioning control unit 5.
Connected to the force end. FIG. 2 shows the offset amount measuring section 6-2 of FIG.
FIG. 2 is a block diagram showing an internal configuration of the device. Offset amount measurement
Servo wedge selector 6 provided at the input end of section 6-2
-2-5 is the output terminal of the reproduction signal level measurement unit 6-2-1.
Connected to input terminal. Reproduction signal level measurement unit 6-2
The output terminal of -1 is connected to the input terminal of the reproduction signal averaging unit 6-2-3.
It is connected. Output terminal of reproduction signal averaging section 6-2-3
Is connected to the input terminal of the playback signal maximum value position detector 6-2-4
Have been. Output of Reproduction Signal Maximum Value Position Detection Unit 6-2-4
The force end is connected to the input end of the magnetic head offset recording section 7.
Have been. The output terminal of the head fine movement unit 6-2-2 is a reproduction signal.
The level measuring unit 6-2-1 is connected to another input terminal.
You. In the reproduction signal averaging section 6-2-3,
The measurement signal provided at the input terminal of the raw signal averaging unit 6-2-3
The output end of the edge averaging unit 6-2-3-1 is the measured value averaging unit 6.
-2-3-2. Average of measured values
The output terminal of 6-2-3-2 is a sudden disturbance canceling unit 6-2-.
3-4 is connected to the input terminal. Sudden disturbance remover 6
The output terminal of -2--3-4 is a measurement position averaging unit 6-2-3-3.
Connected to the input terminal of the head fine movement unit 6-2-2.
The output terminal of the measurement position averaging unit 6-2-3-3 is a reproduction signal.
It is connected to the input terminal of the maximum value position detector 6-2-4.
You. The reproduction signal maximum value position detection unit 6-2-4 performs measurement decomposition
It has a performance improving section 6-2-4-1. FIG. 3 shows the magnetic disk 1 of the magnetic head 2.
FIG. 2 is a plan view of the surface facing the magnetic disk of the first embodiment.
In the device, a composite magnetic head 2 for recording and reproducing is
It is provided at the end of the air head slider 3. Magnetic head
A thin-film inductive head 2 which is a recording head
-1 and a magnetoresistive head (hereinafter referred to as a reproducing head).
2-2 is a magnetic shield plate 2-3
-2 apart from each other by a predetermined distance. Magnetic
A magnetic sheet is provided between the head 2 and the magnetic head slider 3.
A field plate 2-3-1 is provided. MR head 2-
2, induction type head 2-1, shield plates 2-3-1 and 2
-3-2 are each provided via a protective layer of alumina 2-4,
It is held by a magnetic head slider 3. Magnetic heads
The rider 3 is attached to the positioning mechanism 4 via the arm 3A.
It is attached. FIG. 4 and FIG.
Explanation of yaw angle in dynamic actuator
FIG. 2 is a plan view of a magnetic disk drive for the present invention. In FIG.
The arm 3A holding the magnetic head slider 3 is a voice
The positioning mechanism 4 having the il motor 4A
It rotates around the bot 4-1. Magnetic head slider 3
Is located at the center of the data area A of the magnetic disk 1.
The magnetic disk 1 so that the yaw angle becomes zero.
The positional relationship with the mechanism 4 is set. Tiger in the figure
A track 100 is a zero yaw angle track. (A) of FIG.
As shown in the enlarged view of FIG.
When the track is positioned on the inner track 100-1
The direction of the center line 23A of the arm 3A and the track 100
-1 center line 100-1-C tangent line 100-1-T
Between them, an inner track yaw angle 200-1 occurs.
Also, as shown in the enlarged view of FIG.
2 is the track 100-2 on the outer side of the track 100
When positioned, the center line 23 of the slider arm 3A
A direction and the center line 100-2-C of the track 100-2
Between the outer track Y and the direction of the tangent line 100-2-T.
An angle 200-2 occurs. These yaw angles 200-1 and 200-2
As a result, the magnetic head
The off-track of the node 2 will occur. In FIG.
As shown in the enlarged view of FIG.
Tangent to centerline 100-C when positioned at 100
100-T, inductive head 2-1 and MR head 2-2
Center line of the slider arm 3A which is the geometric center line of
23A are substantially parallel. Therefore, during recording, playback
Servo track sometimes described later with MR head 2-2
And the MR head 2-2 is detected.
On-track at the center of the robot track
Recording and reproduction are possible. Induction head 2-1 and MR head
Each magnetic center of the head 2-2 is coincident with the geometric center.
If not, a separate correction is required. Figure
As shown in (a) of FIG.
On track 100-1, yaw angle 200-1 occurs.
Tangent to the center line 100-1-C of the track 100-1
100-1-T is an inductive head 2-1 and an MR head 2
The center line 2 of the slider arm, which is the geometric center line of -2
Does not match 3A. MR caused by yaw angle
Between the geometric center of the head 2-2 and the induction type head 2-1.
The shift amount is defined as “offset amount”. Data recording / reproducing on a magnetic disk
The operation is performed as described below. MR head 2-2
Detects the servo pattern signal of the servo track. De
When recording data, the MR head 2-2 is moved to the servo track.
On-track at the center and data with inductive head 2-1
Record At the time of data reproduction, the MR head 2-2 is invited.
Center of data track written by guided head 2-1
Next, the positioning is performed in consideration of the offset amount. With other methods
When recording data, the inductive head 2-1 moves the data.
MR head so that it is on-track at the center of the track
Position 2-2 at a position that takes into account the amount of offset
When reproducing data, the MR head 2-2 is moved to the data track.
Center of the rack. On the outer peripheral side, FIG.
As shown in FIG.
Tangent 100-2 to center line 100-2-C
-T is the geometry of the inductive head 2-1 and the MR head 2-2.
Coincides with the slider arm center line 23A
do not do. In this case, the servo pattern is
Signal is detected. When recording data, the MR head 2
-2 on-track to the center of the servo track and guide
Data is recorded by the mold head 2-1. When playing data
Indicates that the inductive head 2-1 writes the MR head 2-2.
At the center of the data track, taking into account the amount of offset.
Place it. As another method, when recording the data,
The mold head 2-1 moves on track at the center of the track
As described above, the MR head 2-2 is made in consideration of the offset amount.
Position, and at the time of data reproduction, the MR head 2-
Position 2 at the center of the data track. like this
At the inner or outer circumference of the magnetic disk.
Center of data track written by guided head 2-1
In order to make the MR head 2-2 on-track,
Position offset from the center of the servo track by the offset amount
It is necessary to position the MR head 2-2 first.
That is, in order to perform head positioning with high accuracy
Needs to measure the offset amount with high accuracy. In the magnetic disk drive of the first embodiment,
Measures the offset amount in the following procedure. In FIG.
FIG. 2A is a plan view of the magnetic disk 1. Figure smell
Thus, the recording area of the magnetic disk 1 extends from the outer side to the inner side.
Divided from concentric zone 0 to zone 16
Each zone is composed of a plurality of tracks. Each
The rack has a plurality of location information areas (hereinafter referred to as
Below, it is called servo sector) 300 and data area 200
Have. FIG. 6B shows a track of the magnetic disk 1.
4 types of servos written to servo sector 300
The patterns 300A, 300B, 300C, and 300D are shown.
You. Data is written to the data area 200.
In the figure, a magnetic head 2 -A has a magnetic head 2
When positioned on the center track of the disk 1.
Indicates a state, in this case, a servo pattern 300A for measurement.
Is detected. In the magnetic head 2-B, the magnetic head 2 is magnetic.
When positioned on the outer track of the disc 1
Indicates a state, in this case, a servo pattern 300B for measurement.
Is detected. The arrow R in the figure indicates the direction of rotation of the magnetic disk 1.
Indicates the direction. The method for measuring the offset amount will be described below.
This will be described with reference to FIGS. 1, 2, 5, and 6. Parentheses
The numbers entered represent processing steps. Step (1): Zone 0 on the outer peripheral side ((a) in FIG. 6)
An arbitrary track near the center is connected to the playback head MR.
The head 2-2 is on-track, and the measurement pattern shown in FIG.
The writing section 6-1 controls all servo sections of the track.
The pattern for off-track amount measurement shown in FIG.
Write 300B. Step (2): pattern writing position
Writing of the pattern 300B by the error management unit 6-3
The position error in each servo sector when
Good. The position error may exceed 8% of the track pitch.
Then, the off-track amount measurement pattern 300B is written again.
Get in. Step (3): When the position error is track
If the position error is within 8% of the
Servo sector as a servo sector for measuring the amount of offset.
Selected by the servo wedge selector 6-2-5.
However, the servo sector to be selected depends on the measurement processing time.
Is 1/8 or less of the total number of servo sectors in one track.
You. Step (4): Half-turn the MR head 2-2 toward the outer periphery
The positioning is performed by moving the rack pitch P / 2. Step (5): Reproduction signals of four sectors per rotation
Signal level, and 12 rotations of 12 sectors
Temporarily store data. Step (6): Measurement wedge averaging unit 6
2-3-1, average number of measurements 6-2-3-2 and suddenness
12 data are obtained by the disturbance removing means 6-2-3-4.
Out of those with the maximum value and those with the minimum value
The average value of the ten data was calculated and the average value was calculated internally.
Store in memory. Step (7): The magnetic head is
By moving part 6-2-2, not 1/64 of track pitch
And move to the inner circumference side for positioning. Moved position
The position is called a measurement position. Step (5) and for each measurement position
The process of (6) is repeated 64 times. Figure 7 shows the truck
(N) is a state in which the geometric center coincides with the center line 70.
Of the MR head 2-2 to be traced in the state and the reproduced signal
The level LV is shown in the same figure, and the relationship between the two is shown.
It represents. In the figure, the center of the induction type head 2-1 is shown.
The deviation from the line 70 is indicated by an offset amount. Step (8): Measurement position averaging unit 6 in FIG.
-2-3-3, the outer peripheral side 3 adjacent to each measurement position
And the inner circumference side 3 playback signal levels at a total of 7 measurement positions
Average. Step (9): Reproduced signal maximum value in FIG.
As shown in FIG. 7, the reproduction is performed by the position detection unit 6-2-4.
At the position of the reproducing head 2-2 where the signal level LV becomes maximum,
A measurement point K at a certain maximum value position is detected. FIG.
FIG. 9 is an enlarged view of a peak portion of the reproduction signal level LV,
(A), (b), and (c) are the shapes of the peaks, respectively.
3 shows three typical examples of shapes. Measurement of maximum value position
When the number of the points K is one, the shape of the peak portion is as shown in FIG.
(C). In this case, the measurement resolution improving unit 6-
According to 2-4-1, data at three adjacent positions
Then, the position of the maximum value is derived. Also, measurement of the maximum value position
When there are two or more points K, the shape of the peak portion is as shown in FIG.
(A), the measurement points K at a plurality of maximum value positions₁,
K_TwoWith. These measurement points K₁And K_TwoBased on the maximum value
The position of is derived. Multiple measurement points K₁, K
_{The interval of 2 is equal to the magnetic head offset amount. Step (10): Steps (1) to (
The processing up to 9) is performed in each zone 0 to 16,
The offset amount for each is derived. Step (11): Among the offset amounts for each zone,
14 zones excluding inner and outermost zones 16,0
In each zone from the offset amount of 1, 2, ... 15,
Calculate the relationship between the track number and the offset amount
The data is output to the memory offset storage unit 7 and stored. Step (12): Copy to magnetic disk drive
If there are a number of disks, this measurement corresponds to each disk
This is performed for the magnetic head to be used. By the above measurement, the offset amount of the magnetic head 2
Is stored in the magnetic head offset storage unit 7 for each track.
Keep it. When reproducing data, the track of the magnetic head 2 is
The magnetic head by a distance equivalent to the offset amount corresponding to the
Positioning control by the correction signal output from the
The positioning mechanism 4 is operated by the control unit 5. This
Off the MR head 2-2 from the servo track
To be on-track at the center of the data track.
It becomes possible. As described above, the magnetic disk of the first embodiment
According to the device, the offset amount of the magnetic head 2 can be accurately determined.
By measuring, all the zones of the magnetic disk 1
The MR head 2-2 on the center of the data track
And play the data It becomes possible. << Embodiment 2 >>
The locking device will be described with reference to FIG. FIG.
Showing the configuration of the magnetic disk drive in Embodiment 2 of the present invention.
It is a lock figure. The same elements as those in the first embodiment are denoted by the same reference numerals.
And the duplicate description is omitted. In the second embodiment, in addition to the configuration of the first embodiment,
Recording or playback operation is the same after one rotation of the magnetic disk
Wait for servo sector to arrive and try again, retry
A retry detection unit 9-1 for detecting the presence or absence of an operation;
B) The offset of the magnetic head 2 according to the frequency of occurrence of the operation
Equipped with offset re-measurement unit 9-2 for re-measurement of quantity
ing. The position error amount controlled by the positioning control unit 5 is large.
The frequency of retry operations during recording and playback
If the number of times is 5% or more, perform recording and playback
Command from the offset re-measurement unit 9-2 during the time when it is not
The signal is again moved to the magnetic head offset measuring unit 6 by the signal.
Make the work. In this case, each zone and the offset amount
If there is a linear relationship between approximations,
Offset value for each zone without remeasurement
May be changed based on the relationship. The magnetic head obtained by the re-measurement as described above
Memorize the new value of the offset amount of the
At the time of birth, only the stored offset amount of the magnetic head 2
Move the MR head 2-2 off-track from the servo track.
Let Thereby, the MR head 2-2 is moved to the data track.
On the track. More than
As described above, according to the magnetic disk drive of the second embodiment, the position
If the error is large, or if the
Even if playback is not possible,
It is possible to measure the cut amount with high accuracy,
Highly accurate head positioning becomes possible. [0052]
In the magnetic disk drive of the second embodiment, the offset
Re-measurement of the offset amount by the
The frequency of write operations is less than 5% of the number of recording / reproduction
It is said to be performed in the above case, but even in the case of other ratios
Similar effects can be obtained. In addition, in Example 1 and Example 2,
In magnetic disk drives, the position error
The rewriting of the measurement pattern by the
Perform when the error is more than 8% of track pitch
But 5% or more or 10% or more
Any other ratio may be used. Also, the offset amount measuring unit 6
In the detection of the reproduction signal maximum value position in -2, the magnetic head
Move the track 2 by 1/2 track toward the outer circumference, and move 1 track toward the inner circumference.
Track range (up to inner 1/2 track position)
Up to the measurement. However, from the inner circumference to the outer
It may be measured once. The initial position of the magnetic head 2
Is off track by 1/2 track
Good. Further, the measurement range does not have to be one track. Further, an MR head is used as a reproducing head.
But other read heads such as GMR head
A similar effect can be obtained with the combined magnetic head.
. Also, four servoways per rotation of the magnetic disk
Selected for measurement and the servo sector to be selected is 1
1/8 or more of all servo sectors of the tracks
However, a similar effect can be obtained even if a different number is selected. In addition, the offset measurement unit 6-2 performs the measurement.
And acquired 12 data for 3 rotations.
When the total number of data is less than or equal to 12
Even so, the same effect can be obtained. Also, sudden disturbance rejection
The left part 6-2-3-4 removes the maximum value and the minimum value.
However, removing multiple large values and multiple small values
The same effects can be obtained. Further, when the offset measuring unit 6-2 performs measurement,
Small movement of magnetic head by 1/64 of track pitch
Moved, but moving at other pitches
Like
The effect is obtained. Also, in the offset measuring unit 6-2,
Three or more adjacent positions to detect the maximum value
The average of the reproduced signals at
Similar effects can be obtained by using statistical processing. [0056] The present invention has been described in detail in the above embodiments.
As is apparent from FIG.
Even if the recording density is increased by tracking,
Based on magnetic head offset measured with high accuracy
Thus, the magnetic head can be accurately positioned. As a result, playback
At times, retry operations due to data errors increase and continuous data
The data transfer speed does not decrease.}

_{[Brief description of the drawings] FIG. 1 illustrates a magnetic disk drive according to a first embodiment of the present invention.
Block Diagram. FIG. 2 is an offset amount measuring unit according to the first embodiment of the present invention.
FIG. FIG. 3 is a plan view of the magnetic head according to the first embodiment. FIG. 4 illustrates a magnetic disk drive according to the first embodiment of the present invention.
FIG. 3 is a plan view for explaining a yaw angle. FIG. 5 illustrates a magnetic disk drive according to the first embodiment of the present invention.
FIG. 4 is an enlarged plan view for explaining a yaw angle. FIG. 6A shows a magnetic disk according to the first embodiment of the present invention.
FIG. 4B is a plan view showing a recording area of a magnetic field, and FIG.
Disk servo pattern. FIG. 7 illustrates a magnetic disk drive according to the first embodiment of the present invention.
For explanation of offset measurement FIG. 2 is a plan view of a magnetic disk. FIGS. 8 (a) to 8 (c) are diagrams for Embodiment 1 of the present invention.
Output level for detecting the maximum position of the magnetic disk drive.
Graph of le. FIG. 9 illustrates a magnetic disk drive according to a second embodiment of the present invention.
Block Diagram. FIG. 10 is a block diagram of a first conventional magnetic disk drive.
FIG. FIG. 11 is a block diagram of a second conventional magnetic disk drive.
FIG. [Explanation of symbols] 1 Magnetic disk 2 Composite magnetic head 3 Magnetic head slider 3A arm 4 Positioning mechanism 4A voice coil motor 4-1 pivot 5 Positioning control unit 6 Magnetic head offset measurement unit 6-1 Measurement pattern writing unit 6-2 Offset amount measurement unit 6-2-1 Reproduction signal level measurement unit 6-2-2 Head fine movement section 6-2-3 Reproduction signal averaging unit 6-2-3-1 Average wedge part 6-2-3-2 Measured value averaging unit 6-2-3-3 Measurement position averaging unit 6-2-3-4 Sudden disturbance removal unit 6-2-4 Reproduction signal maximum value position detector 6-2-4-1 Measurement resolution improvement unit 6-2-5 Servo wedge selector 6-3 Position Error Management Unit at Pattern Writing 7 Magnetic head offset storage unit 8 Magnetic head target position correction unit 9-1 Retry detector 9-2 Offset re-measurement unit 23A Geometric center line 100 tracks 100-1 track 100-2 truck 200 data area 200-1 yaw angle 200-2 yaw angle 300 location information area}

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Tatsuhiko Inagaki             Matsushita Electric Industrial Co., Ltd.             Sangyo Co., Ltd. (72) Inventor Toshiyuki Wada             Matsushita Electric, 1006 Kadoma, Kazuma, Osaka             Sangyo Co., Ltd. (72) Inventor Makoto Kuwamoto             Matsushita Electric, 1006 Kadoma, Kazuma, Osaka             Sangyo Co., Ltd. F term (reference) 5D042 LA01 MA05 MA12                 5D096 AA02 BB01 CC01 DD01 DD02                       DD08 EE03 FF04 FF05 FF06                       HH11 KK05 NN10 WW03 WW04

Claims (9)

[Claims] 1. A composite magnetic head having a recording head for recording data on a magnetic disk and a reproducing head for reproducing the recorded data, a magnetic head slider for holding the composite magnetic head, and a magnetic head slider. A positioning mechanism for rotating and positioning the magnetic head at a target track on the magnetic disk; a position of the magnetic head relative to the target track based on servo information written on the magnetic disk and reproduced by the magnetic head; A positioning control unit that controls a positioning operation of the positioning mechanism unit by a position error signal indicating a mismatch of the measurement pattern; a measurement pattern writing unit that writes a servo pattern for obtaining an offset measurement signal on a magnetic disk by the recording head; Connect the head to the head positioning mechanism While fine movement by de positioning control unit measures the position of the reproduced signal output is maximum,
An offset amount for measuring a magnetic head offset amount of a difference between a position of the reproducing head and a position of the recording head in a radial direction of the magnetic desk, which is caused by a positional relationship between the reproducing head and the recording head on the magnetic head. A magnetic head offset measuring means having a measuring means and a pattern writing position error managing means for causing the servo pattern to be written again according to the position error at the time of writing the offset amount measuring signal; Magnetic head offset storing means for storing the magnetic head offset amount measured by the measuring means, and storing the relationship between the position of the track accessed by the magnetic head and the measured magnetic head offset amount, and the reproducing head during reproduction Is recorded on the target track When following the information data, the magnetic head target position correction means for outputting a correction signal for correcting the positioning target position of the magnetic head to the positioning control unit based on the magnetic head offset amount read from the magnetic head offset storage means. A magnetic disk drive comprising: 2. The apparatus according to claim 1, wherein the offset amount measuring means includes: a read signal level measuring means; a head fine moving means for moving the magnetic head by a very small distance; and a position of the magnetic head moved and positioned by the head fine moving means. Reproduction signal averaging means for averaging the levels of a plurality of reproduction signals, reproduction signal maximum value position detection means for detecting the position of the magnetic head at which the maximum reproduction signal is obtained, and a plurality of servo wedges having a small position error during writing 2. The magnetic disk drive according to claim 1, further comprising: a servo wedge selecting unit that selects a servo wedge for measuring a level of the reproduction signal. 3. The reproduction signal averaging means: a measurement wedge averaging means for averaging reproduction signal levels of a plurality of servo wedges selected by the servo wedge selection means; Measurement value averaging means for obtaining an average of the measurement values; measurement position averaging means for averaging the measurement values of the reproduction signal levels at a plurality of adjacent measurement positions; and measuring the reproduction signal level in the calculation of the measurement value averaging means. 3. The magnetic disk drive according to claim 2, further comprising an abrupt disturbance removing means for excluding a maximum value and a minimum value. 4. The reproduction signal maximum value position detecting means includes: a position of the magnetic head at which the measured value of the level of the reproduction signal is the maximum value; a position of the magnetic head at which the second largest value is obtained; The position of the magnetic head at which the measured value of the reproduced signal takes the maximum value, based on the position of the magnetic head at which the measured value of the reproduced signal takes two maximum values. 3. The magnetic disk drive according to claim 2, further comprising a measurement resolution improving means for improving the detection accuracy of the magnetic disk. 5. The reproduction signal maximum value position detecting means calculates an average of reproduction signals at three or more adjacent measurement positions in order to prevent a reproduction signal level from being saturated by a measurement position on a magnetic disk. The magnetic disk drive according to claim 4, wherein 6. The magnetic head target position correcting means, when writing a servo pattern for obtaining an offset amount measuring signal on a magnetic disk by a recording head, positions a reproducing head at the center of a target track. The magnetic disk drive according to claim 1. 7. The offset amount measuring means includes zone averaging means for approximately calculating a magnetic head offset amount for each zone divided by a radius of a magnetic disk, and an innermost peripheral zone and an outermost peripheral zone. 3. The magnetic disk drive according to claim 1, further comprising a linear approximation unit that removes from the calculation for obtaining the average. 8. The pattern writing position error management means, if the position error between the target track and the magnetic head at the time of writing the servo pattern is 8% or more of the track pitch, sends the offset amount measurement signal to the magnetic disk again. 2. The magnetic disk drive according to claim 1, wherein a servo pattern to be obtained is written. 9. A retry detecting means for detecting a retry operation for repeating the servo pattern writing operation or the reproducing operation for each rotation of the magnetic disk, and a magnetic head offset measuring unit for remeasurement according to the frequency of the retry operation. 2. The magnetic disk drive according to claim 1, further comprising an offset re-measurement unit for performing the following.