JPH09147337A - Magnetic disk device and head positioning adjustment method in magnetic disk device - Google Patents

Abstract

(57) Abstract: Even if the center position of the effective sensitivity is deviated due to variations in sensitivity distribution of individual MR heads or characteristic changes, the optimum write position is always with respect to the target track on the disk. Alternatively, position the head at the read position. SOLUTION: Measurement data is written to a specific measurement track n by a recording head of an MR head, and the MR is separated by a distance (-Nd) obtained by multiplying the maximum off-track number N by an off-track pitch amount d from the write scanning center position D1. The MR head is off-tracked according to the reproduction state of the servo burst signal by the element, and the MR element is moved and positioned from here to the distance (Nd) at the pitch d to reproduce the output level E of the measured data.
Is measured and the off-track distance from the write center position D1 of the measured data for which the peak value Ep is obtained is calculated as the R / W offset amount DOFS of the MR element with respect to the recording head of the MR head.
Then, the head movement position with respect to the target track at the time of data reading is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device for optimally controlling writing and reading positions of a magnetic disk by a magnetic head and a head positioning adjusting method in the magnetic disk device.

[0002]

2. Description of the Related Art Generally, in a magnetic disk device, a magnetic head for reading and writing data is roughly classified into an induction type head and a magnetic flux response type head because of the difference in operation principle. MIG heads, thin film heads, and the like, which are magnetic heads of magnetic disk devices currently mainly used, belong to the induction type heads.

On the other hand, when the recording density of the magnetic disk device is increased, the reproduction signal per bit read by the magnetic head becomes weak, and it becomes difficult to read the reproduction signal correctly. Is required.

Therefore, an MR head has appeared as one of the magnetic heads capable of reproducing with higher sensitivity than the conventional magnetic head. This MR head is a magnetic flux response type head that detects a magnetic field generated on the surface of a magnetic disk as a change in resistance value by utilizing an anisotropic magnetoresistive effect. It has the characteristics of high sensitivity and the magnitude of the reproduced signal not depending on the running speed of the magnetic disk.

However, this MR head (MR element) is
Since it is a read-only head, a write-only thin-film head is required in addition to the MR head to configure a magnetic head of a readable / writable magnetic disk device.

Therefore, in consideration of manufacturability and the like, a recent magnetic disk device uses a thin film head as a write head and an MR head as a read head, and separates recording / reproducing. The combined head (hereinafter referred to as "MR
It is partially commercialized as a "head").

10A and 10B are views showing the basic structure of the MR head. FIG. 10A is a sectional perspective view thereof, and FIG. 10B is a disk relative plan view thereof. In FIG. 10, 1 is an upper write pole, 2 is a lower write pole, 3 is a write gap, 5 is a write coil, and the lower write pole 2 is an MR upper shield, and an MR element 4 and an MR lower shield 6 for reading are used. They are provided adjacent to each other in sequence.

In this MR head, the recording head portion (1
˜5) and the reproducing head section (2, 4, 6) are separated from each other, the write lower pole (MR upper shield) 2 must be positioned between them for recording / reproducing. A few μm to a few μm between both gaps
Therefore, the distance L of

Further, in a magnetic disk device, a rotary actuator is widely used as a moving mechanism for moving the magnetic head between tracks on the disk. In this case, as shown in FIG. 11, the magnetic head is a disk. Since the head is moved along a curve with respect to the track direction (radial direction) x, the azimuth angle (disk running direction) that changes according to the track position on the disk (position in the disk radial direction x) with respect to the head center axis direction. An angle θ formed between the direction y and the normal line of the head gap L is generated.

FIG. 11 shows, as a simple case, a shift between a write track and a read track due to the azimuth angle θ of the MR head with respect to the disk when the sensitivity center of the MR element coincides with the center line of the write element. FIG.

That is, in the case of an MR head, the recording / recording
Due to the inter-reproduction gap L and the azimuth angle θ, there is a deviation in the track direction x between the write track corresponding to the write gap 3 and the read track corresponding to the MR element 4, as shown in the following equation (1). The quantity DOFS 'is produced.

DOFS '= Lsin θ (1) Here, the shift amount DOFS' in the track direction x between writing and reading in the MR head is defined as the R / W offset amount at the skew angle θ.

The R / W offset amount DOFS 'shown in the equation (1) is a deviation between the effective recording center position by the recording head and the effective reproduction center position by the reproducing head corresponding to the central axis direction of the head itself. R / W offset amount DH
Is “0”, that is, the center line of the write element is MR
This is the case when it coincides with the sensitivity center of the element 4.

When the write track and the read track are deviated in this way, an error occurs when the data on the track adjacent to the target track is read when reading the data, or an error occurs when the data is written on the target track. There is a problem that an error occurs when data is written in the adjacent track.

Therefore, conventionally, the following two methods have been used as measures for solving such a problem. (1) The structure of an MR head in which the width TWW of the write head 1 is wide and the width TWR of the read head 4 is narrow, that is,
With the structure of "wide write, narrow read", the above R
Even if the / W offset amount DOFS 'occurs, the read head 4 is positioned above the widely written data.

However, this method is a factor that hinders the improvement of the track density because the writing width to the disk needs to be widened. (2) The R / W offset amount DOFS 'is calculated in advance based on the azimuth angle θ when the MR head is located at an arbitrary position on the disk, and the R / W offset is set during writing or reading. A method in which the heads are positioned by shifting the amount DOFS 'so that each head is adjusted to the optimum position during writing and reading.

[0017]

As described above, if the head position is shifted during writing and reading according to the R / W offset amount DOFS 'of the MR head to adjust the positioning, the track density is lowered. The optimum position control of the head is possible without any problem, but the R / W offset amount DOFS '
Is influenced by the sensitivity distribution and the magnetization characteristics of the MR element 4 in addition to the numerical value that can be calculated in advance by the geometrical dimension based on the recording / reproducing distance L and the azimuth angle θ. You must get the offset amount.

The problems of the head alone that affect the R / W offset amount of the MR head will be described below (a) to (d).
Will be described. 12 is a diagram showing the up-down symmetry of the output waveform and the off-track characteristic of the output amplitude in the MR element (excerpt from Hitachi Metals Technical Report vol1. <1995>).

According to FIG. 12, it can be seen that the center position of the effective sensitivity seen at the center of the area of the output waveform and the peak point deviates from the geometrical center position of the MR element 4, and the fluctuation of the bias. It can be seen that the magnetization characteristic changes.

Here, the effective offset amount of the MR head is defined as R / W offset amount DOFS. DOFS = Lsin θ + DH cos θ (3) where DH is the R / W offset amount which is the deviation between the effective recording center position by the recording head and the effective reproduction center position by the reproducing head corresponding to the central axis direction of the head itself. .

(A) Each head has an offset amount which is optically varied due to the influence of alignment change in the manufacturing process of the MR head. (B) Since the MR element 4 has an asymmetric sensitivity distribution in which the element sensitivity is not symmetrical in the track width direction, the optical offset amount differs from the magnetic or effective offset amount (see FIG. 12).

(C) The effective offset amount (R / W offset amount DOFS) of the MR head is the height of the MR element 4,
In addition to the optical offset variation described in (a), which is influenced by the bias distribution and the like, it is a cause of individual variation of the head.

(D) The effective offset amount (R / W offset amount DOFS) of the MR head may be small defects or an abnormal magnetic domain structure inside the head. May change.

That is, 2 for preventing a writing or reading error caused by the R / W offset amount DOFS 'which is performed in the conventional magnetic disk device.
The two methods (1) and (2) do not adjust the head position based on the R / W offset amount DOFS in consideration of the effects of variations in MR heads and characteristic changes. There is a possibility that an error may occur such that the data is written in or the data of the track adjacent to the target track is read.

Therefore, even when the MR head positioning control is performed based on the R / W offset amount DOFS 'calculated from the geometrical dimension using the method (2), variations in individual heads and changes in characteristics are caused. Further offset shift due to the influence must be taken into consideration, and there is a problem that becomes an obstacle for improving the track density (recording density).

The present invention has been made in view of the above problems, and even if the center position of the effective sensitivity is deviated due to the influence of variations in the sensitivity distribution of individual MR heads or characteristic changes, the magnetic disk It is an object of the present invention to provide a magnetic disk device and a head positioning adjustment method in a magnetic disk device that can always position the head at an optimum write position or read position with respect to the above target track.

[0027]

That is, a magnetic disk device according to the present invention is a magnetic disk device using an MR head, and the recording effective position of the recording head with respect to the track direction of the magnetic disk and the reproducing head (MR element). ), The offset amount measuring means for measuring the recording / reproducing offset amount with respect to the effective reproducing position, and the MR based on the recording / reproducing offset amount measured by the offset amount measuring means.
A positioning adjusting means for adjusting the positioning of the head is provided.

That is, in the magnetic disk device according to the present invention, the recording / reproducing offset amount between the effective recording position of the recording head and the effective reproducing position of the reproducing head (MR element) with respect to the track direction of the magnetic disk is obtained by measurement.
Based on the measured recording / reproducing offset amount, the M
Since the positioning of the R head is adjusted, the head position can be adjusted to the optimum writing and reading position with respect to the target track.

A head positioning adjusting method in a magnetic disk device according to the present invention is a head positioning adjusting method in a magnetic disk device using an MR head, in which a specific track on the magnetic disk is recorded by the recording head of the MR head. Measurement data is recorded on the track, and the measurement data recorded on the specific track is reproduced while the reproducing head (MR element) of the MR head is off-track, and is recorded corresponding to the peak value of the reproduction signal at each off-track position. / The reproducing offset amount is measured, and the positioning of the MR head is adjusted based on the recording / reproducing offset amount.

That is, in the head positioning adjusting method in the magnetic disk apparatus according to the present invention, the measurement data is recorded on a specific track on the magnetic disk by the recording head of the MR head, and the measurement data recorded on the specific track is recorded as described above. The reproduction is performed while the reproducing head (MR element) of the MR head is off-tracked, and the recording / reproducing offset amount is measured corresponding to the peak value of the reproducing signal at each off-track position. Since the positioning adjustment of the MR head is performed, the center position of the effective sensitivity of the MR element can be accurately positioned at the center position of the target track when reading recorded data, for example.

Further, another magnetic disk device according to the present invention is a storage unit for storing a recording / reproducing offset amount which is regularly measured by the offset amount measuring unit, and a recording / reproducing offset stored in the storing unit. When the change of the amount with time becomes equal to or more than a predetermined value, a notifying means for notifying that effect is provided.

That is, in another magnetic disk device according to the present invention, when the change with time of the recording / reproducing offset amount which is regularly measured by the offset amount measuring means becomes a predetermined value or more, the user is notified. So MR
It is possible to prevent problems such as data loss due to head abnormality.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a magnetic disk device according to an embodiment of the present invention. A magnetic disk 11 is held by a disk holder 11a and rotatably arranged on a base 10 which is a case of the magnetic disk unit.
An arm 13 that rotates about the shaft 12 is provided on the top.

At the tip of one end of the arm 13, the MR
Heads 14 (1, ~, 6) are attached to the arm 13
The MR head 14 is moved (seeked) in the track direction (radial direction) x of the magnetic disk 11 with the rotation.

A VCM (voice coil motor) 15 is provided on the other end of the arm 13, and the MR 13 is rotated by rotating the arm 13 by the VCM motor 15.
The head 14 is controlled to move in the track direction (radial direction) x on the surface of the disk 11.

An electronic circuit 16 for controlling writing / reading of data in the magnetic disk unit is provided in a space adjacent to the magnetic disk 11 and the VCM motor 15 in the base 10.

In FIG. 1, in particular, the positioning system control circuit of the MR head 14 is extracted from the electronic circuit 16. The positioning system control circuit includes the MR head 14, the R / W-IC 21, the head position information generation circuit 22, the head reproduction output measurement circuit 23, the head positioning calculation circuit 24, the optimum offset amount calculation circuit 25, and the offset table 26. , VCM drive circuit 27 is provided.

The reproduction output signal when the data on the magnetic disk 11 is read by the MR element 4 of the MR head 14 is supplied to the head position information generating circuit 22 and the head reproduction output measuring circuit 23 via the R / W-IC 21. Is supplied to.

The head position information generating circuit 22 outputs the MR based on the address signal and the position error signal (burst signal) in the servo data recorded for each track (sector) of the magnetic disk 11 reproduced by the MR head 14. The head position data generated by the head position information generation circuit 22 is calculated by detecting the track position and sector position of the head 14 (MR element 4) on the magnetic disk 11 and generating the current head position data. Sent to circuit 24.

FIG. 2 is a diagram showing the principle of detecting the head position based on the servo burst signal in the head position information generating circuit 22 of the magnetic disk device. FIG. 2A shows the servo burst recorded on the magnetic disk 11. Signal and M
The figure which shows the relative positional relationship with the R head 14 (MR element 4), the figure (B) shows the reproduction output waveform of the servo burst signal by the MR head 14 (MR element 4), and the figure (C) shows the MR. FIG. 7 is a diagram showing reproduction output characteristics of a servo burst signal with respect to a track direction position of the head 14 (MR element 4).

That is, when the center of the effective sensitivity of the MR element 4 is accurately positioned, for example, at the center position on the track, the reproduced output waveform by the MR element 4 is the signal of both A and B of the servo burst signal. For the same level, and in the state where the center of the effective sensitivity of the MR element 4 is deviated in the direction of the burst signal B from the center position on the track, for example, the reproduction output waveform by the MR element 4 Is, as shown in FIG.
The output level of the servo burst signal A decreases and the output level of the servo burst signal B increases according to the deviation amount.

Therefore, as shown in FIG. 2C, if the reproduction output level E of the servo burst signal with respect to the position x in the track direction of the MR element 4 is monitored based on the following equation (2), the MR element 4 can be detected. It is possible to detect how much ± distance the effective center deviates from the track.

E = (A−B) / (A + B) Equation (2) That is, the head positioning arithmetic circuit 24 determines the target head position on the magnetic disk 11,
According to the positioning signal, the VCM drive circuit 27 outputs V
When the CM motor 15 is driven, a reproduction output signal from the MR head 14 is supplied to the head position information generating circuit 22 in accordance with the movement of the MR head 14 on the magnetic disk 11 by the rotation of the arm 13, The current head position data generated based on the servo burst signal is fed back to the head positioning calculation circuit 24.

As a result, the VCM motor 15 is driven so that the current head position data generated by the head position information generating circuit 22 matches the head position data determined by the head positioning arithmetic circuit 24, and the MR The head 14 is moved to the target position on the magnetic disk 11.

On the other hand, the head reproduction output measuring circuit 23 uses M
This is for measuring the signal level of the reproduction output signal supplied from the R head 14 via the R / W-IC 21 in accordance with the reading of the data on the magnetic disk 11. The MR measured by the head reproduction output measuring circuit 23 is measured. The reproduction output level data from the head 14 is stored in the optimum offset amount calculation circuit 25.
Sent to

In the measurement mode of the R / W offset amount DOFS in the MR head 14, the optimum offset amount calculation circuit 25 stores the reference position data on the magnetic disk 11 in which the measurement data set in the offset table 26 is written. In connection with the reading of the current head position data obtained from the head position information generating circuit 22 through the head positioning arithmetic circuit 24 and the measurement data written on the magnetic disk 11 obtained by the head reproduction output measuring circuit 23. The optimum R / W offset amount DOFS of the current MR head 14 is obtained based on the level data of the reproduction output signal. The R / W offset amount DOFS obtained by the optimum offset amount calculation circuit 25 is an offset. It is set on the table 26.

Here, the optimum offset amount calculation circuit 2
In 5, the magnetic disk 1 on which the measurement data is recorded
The R / W offset amount DOFS with respect to the reference position (specific track or specific sector) on 1 is obtained, and the R / W offset amount DOFS with respect to the reference position is set to the recording / reproducing head distance L and Corrected based on the azimuth angle θ at each track position on the magnetic disk 11, an appropriate R / W offset amount DOFS corresponding to each track position on the magnetic disk 11 is obtained. Individual R / W offset amounts DOFS corresponding to all track positions on the magnetic disk 11 are set in the offset table 26.

Then, the head positioning arithmetic circuit 24
Then, the MR set in the offset table 26
For example, the read position of the MR head 14 with respect to the target track is corrected and determined based on the optimum R / W offset amount DOFS according to the position of each track on the magnetic disk 11 of the head 14.

FIG. 3 shows the distance L between the recording / reproducing heads in the MR head 14 of the magnetic disk device, the azimuth angle .theta., And the R / W offset amount which is the difference between the effective recording position W0 and the effective reproducing position R0 of the head itself. It is a figure which shows the relative relationship of DH and the amount of R / W offset DOFS with respect to a measurement data track.

Here, the R / W offset amount DOFS with respect to the disk track in the MR head 14, the recording / reproducing head distance L, the azimuth angle θ, and the head itself R.
The following equation (3) is established between / W offset amount DH.

DOFS = Lsin θ + DH cos θ (3) Here, the distance L between the recording / reproducing head and the azimuth angle θ of each track on the magnetic disk 11 are the geometric design of the MR head 14 and the magnetic disk unit. Since it is determined in advance from the dimensions, the optimum R / W in a specific track on the magnetic disk 11 in which the measurement data is recorded
By obtaining the offset amount DOFS by measurement, if the R / W offset amount DH, which is the difference between the effective recording position W0 and the effective reproduction position R0 of the head itself, is obtained by calculation, substitute the azimuth angle θ for each of the other tracks. By doing so, the optimum R / W offset amount DOFS for each track can be obtained.

On the other hand, the azimuth angle θ of the MR head 14 with respect to the disk track changes linearly between the disk inner peripheral side and the disk outer peripheral side, and accordingly, the R / W offset amount DOFS also changes. Since it changes linearly between the inner circumference side and the outer circumference side of the disk, the MR head 14 for each track in each track (or sector) of the inner circumference side track, the middle track, and the outer circumference side track, for example. R / W offset amount DOF
Si, DOFSm, DOFSo were obtained by measurement, and R /
Data in which the W offset amounts DOFSi, DOFSm, DOFSo are linearly complemented may be set in the offset table 26 to obtain the optimum R / W offset amount DOFS for all the disk tracks.

Next, the positioning adjustment operation of the MR head 14 in the magnetic disk device having the above-mentioned structure will be described. FIG. 4 is a flow chart showing the measuring process of the R / W offset amount DOFS for the specific disk track of the MR head 14 in the magnetic disk device according to the first embodiment of the present invention.

FIG. 5 shows the writing / reading state of the measurement data accompanying the measurement process of the R / W offset amount DOFS for the specific disk track of the MR head 14 in the magnetic disk device according to the first and second embodiments of the present invention. FIG.

FIG. 6 is an off-track at the time of reproducing the measurement data accompanying the measurement processing of the R / W offset amount DOFS for the specific disk track of the MR head 14 in the magnetic disk device according to the first and second embodiments of the present invention. FIG. 6 is a diagram showing a change in a reproduction output level E with respect to an amount D.

That is, in the positioning system control circuit of the MR head 14 in FIG. 1, the R / W offset amount DOFS of the MR head 14 with respect to a specific disk track.
When the measurement process of No. 1 is started, first, the measurement track n which is the target of writing / reading of the measurement data to / from the magnetic disk 11 and the measurement data written in this measurement track n are successively read by the MR head 14 in a trace amount. An off-track pitch amount d for reading while off-tracking, and a maximum off-track number N to be off-tracked by this off-track pitch amount d are set in the offset table 26 (step S1).

For example, when the designed track width of the magnetic disk 11 is 4 μm, the off-track pitch amount d is set to a value of about 0.1 μm. Then, in the head positioning arithmetic circuit 24, the VCM motor 15 is driven and controlled by the VCM drive circuit 27 with the measurement track n set in the offset table 26 as the target track, and the servo read by the MR head 14 (MR element 4). Based on the reproduction signal of the data, the MR element 4 is positioned at the initial position D0 on the measurement track n (step S2).

In this case, for example, the initial position D0 is, for example, the center position of the measurement track n. And the M
The R element 4 is the measurement track N on the magnetic disk 11.
When positioned at the upper initial position (center position) D0, measurement data is written on the measurement track n by the recording heads (TF) 1, 2, 3, 5 of the MR head 14 (step S3) (Fig. 5).

Here, "-N" corresponding to the maximum off-track number N is set to the off-track number register j of the offset table 26, and "0" is set to the reproduction peak value register Ep to set the peak. "N + 1" is set to the value-corresponding off-track number register jp (step S4).

Then, the MR element 4 writes the measurement data at the center position D1 (in this case, since the measurement data was written at the center position D0 of the measurement track n, D1 = D0 =
0) is positioned off-track by the distance D given by the following equation (4) (step S5).

D = D1 + j × d (4) In other words, the write data center position D1 of the measured data is the distance D obtained by multiplying "-N" set in the off-track number register j by the off-track pitch amount d. (= D0 = 0)
Then, the MR element 4 is positioned off-track (see FIG. 6).

Here, the reproduction output level E of the measurement data read by the MR element 4 is measured by the head reproduction output measuring circuit 23, and the measured reproduction output level E is measured.
Is greater than the value set in the reproduction peak value register Ep by the optimum offset amount calculation circuit 25 (steps S6 and S7).

The operation center position D of the measurement data
When it is judged that the reproduction output level E of the MR element 4 measured at the off-track position D (= −N × d) for 1 at this time is higher than the value set in the reproduction peak value register Ep. The reproduction output level E measured this time is set in the reproduction peak value register Ep, and the current off-track number (in this case "-N") set in the off-track number register j corresponds to the peak value. It is set in the off-track number register jp (steps S7 → S8).

Here, it is determined whether or not “j ≧ N”, that is, whether the current off-track number (“-N” in this case) set in the off-track number register j has reached the maximum off-track number N. If it is determined that the number of off-tracks is not reached, the number j of off-tracks this time is incremented by 1, and the position off-tracked by the distance D given by the equation (4) is again expressed as “(N− + 1) × d in this case”. , The MR element 4 is positioned, and the reproduction output level E thereof is measured (steps S9 → S10 → S5, S6).

By repeating the above-described steps S5 to S10, the off-track from the maximum off-track distance (-N.times.d) with respect to the center position D0 of the measurement track n as shown in FIGS. Track pitch amount d
The reproduction output level E by the MR element 4 is sequentially measured, and the reproduction peak value register Ep and the peak value corresponding off-track number register jp are rewritten.
For example, when it is determined that the measured reproduction output level E becomes lower than the reproduction output level E set in the reproduction peak value register Ep at the previous measurement, the reproduction peak value register Ep is obtained by the previous measurement. The peak value of the reproduced output level thus obtained and the off-track number of the MR element 4 at the time of the previous measurement are held in the peak value-corresponding off-track number register jp, respectively (steps S7 → S9).

Further, the processing of measuring the reproduction output level E by the MR element 4 for each off-track pitch amount d is repeated until the current off-track number j reaches the maximum off-track number N (steps S9 → S10 → S5
S6, S7 → S9).

Then, the reproduction output level E is measured at the position where the number j of off-tracks this time reaches the maximum number N of off-tracks and is off-tracked by the distance D (= N · d) from the center position D0 of the measurement track n. When this is performed, it is determined that the peak value-corresponding off-track number held in the peak value-corresponding off-track number register jp is smaller than the maximum off-track number N, that is, it is not a measurement error. The distance given by "(D1-D0
) + Jp × d ”is the MR head 14 at the measurement track n.
Is calculated as the R / W offset amount DOFS (steps S10 → S5, S6, S7 → S9 → S11 → S1).
2).

DOFS = (D1−D0) + jp × d (5) In this case, since the operation center position D1 of the measurement data is the center position D0 of the measurement track n, the R / W offset amount DOFS is (jpp). Xd), which is the distance obtained by multiplying the off-track number NEp corresponding to the peak value of the reproduction output by the MR element 4 by the off-track pitch amount d.

On the other hand, if it is determined in step S11 that the peak value-corresponding off-track number held in the peak value-corresponding off-track number register jp is larger than the maximum off-track number N, it is judged as a measurement error. Then, the maximum number of tracks N initially set in step S1 is reset and the series of measurement processes is executed again (steps S11 → S13).

Thus, when the R / W offset amount DOFS of the MR head 14 on the measurement track n is obtained by the optimum offset amount calculation circuit 25, the specific track n
Based on the R / W offset amount DOFS at the recording / reproducing head L and the azimuth angle θ at the specific track n, the effective recording position W0 and the effective reproducing position R0 of the head itself are deviated according to the above equation (3). The R / W offset amount DH is calculated. Further, the azimuth angle θ in each of the other tracks is substituted, and the MR head 14 which is optimum for all the tracks on the magnetic disk 11 is obtained.
R / W offset amount D.sub.OFS is calculated and set in the offset table 26.

On the other hand, the measurement process of the R / W offset amount DOFS of the MR head 14 in FIG. 4 is performed for three measurement tracks ni, nm and noi of the inner track, the middle track and the outer track of the magnetic disk 11, for example. Perform three R / W offset amounts DOFSi, DOFSm, DOFSo
Is linearly complemented to obtain the optimum R / W offset amount DOFS for all the disk tracks in the offset table 2
It may be set to 6.

As a result, the head positioning arithmetic circuit 24
Then, the MR set in the offset table 26
The MR element 4 in the MR head 14 is determined by correcting, for example, the read position of the MR head 14 with respect to the target track based on the optimum R / W offset amount DOFS according to each track position on the magnetic disk 11 of the head 14. The effective reproduction position R0 of is accurately positioned with respect to the center position of the target track.

Therefore, according to the magnetic disk device having the above-described structure, the specific measurement track n on the magnetic disk 11 is measured.
On the other hand, the recording heads (TF) 1, 2,
The measurement data is written by 3 and 5, and the maximum off-track number N is multiplied by the off-track pitch amount d from the scanning center position D1 where the measurement data is written, and the distance is (-Nd) M.
The MR head 14 is offtracked according to the reproduction state of the servo burst signal by the R element 4, and the MR element 4 is moved from here to the distance (N · d) for each offtrack pitch amount d.
To move and position the playback output level E of the measured data.
Is measured, and the off-track distance from the write center position D1 of the measurement data, at which the peak value Ep of the reproduction output level E is obtained, is set to the recording head (TF) 1 of the MR head 14.
R / W offset amount D of MR element 4 with respect to 2, 3 and 5
Since it is obtained as OFS and the head movement position with respect to the target track at the time of reading data is corrected, the MR element 4 can be positioned at the optimum read position with respect to the target track.

Therefore, M for the magnetic disk 11
If the R / W offset amount DOFS of the R head 14 is measured, for example, when the power is turned on, when a read error occurs, when the sense current is changed, or at regular intervals of a predetermined period, the recording / reproducing head interval is increased. Always correct M considering not only R / W offset amount DOFS 'based on geometrical dimensions such as distance L and azimuth angle θ, but also further offset deviation due to variations in individual heads and characteristic changes
The positioning of the R head 14 can be adjusted, and the track density (recording density) of the magnetic disk 11 can be further improved.

The R of the first embodiment shown in FIG.
In the process of measuring the / W offset amount DOFS, the off-track distance from the write center position D1 of the measured data at the time when the peak value Ep of the reproduction output level E read by the MR element 4 is obtained is the R / W offset amount. Although the configuration is calculated as D OFS, for example, as shown in FIG.
The off-track distance from the write center position D1 of the measurement data corresponding to the center (A1 = A2) of the area surrounded by the reproduction output level E at each off-track position of the R element 4 is
The configuration may be such that the R / W offset amount DOFS is obtained (see FIG. 7).

FIG. 7 is a flow chart showing the measuring process of the R / W offset amount DOFS for the specific disk track of the MR head 14 in the magnetic disk device according to the second embodiment of the present invention.

That is, in the positioning system control circuit of the MR head 14 in FIG. 1, the R / W offset amount DOFS of the MR head 14 with respect to a specific disk track.
When the measurement process of No. 1 is started, first, the measurement track n which is the target of writing / reading of the measurement data to / from the magnetic disk 11 and the measurement data written in this measurement track n are successively read by the MR head 14 in a trace amount. The off-track pitch amount d for reading while off-tracking, and the maximum off-track number N to be off-tracked by this off-track pitch amount d are set in the offset table 26 (step A1).

For example, when the designed track width of the magnetic disk 11 is 4 μm, the off-track pitch amount d is set to a value of about 0.1 μm. Then, in the head positioning arithmetic circuit 24, the VCM motor 15 is driven and controlled by the VCM drive circuit 27 with the measurement track n set in the offset table 26 as the target track, and the servo read by the MR head 14 (MR element 4). Based on the data reproduction signal, the MR element 4 is positioned at the initial position D0 on the measurement track n (step A2).

In this case, for example, the initial position D0 is, for example, the center position of the measurement track n. And the M
The R element 4 is the measurement track N on the magnetic disk 11.
When positioned at the upper initial position (center position) D0, measurement data is written by the recording heads (TF) 1, 2, 3, 5 of the MR head 14 on the measurement track n (step A3) (Fig. 5).

Here, "0" is set to the reproduction output area register SUM of the offset table 26,
"-N" corresponding to the maximum off-track number N is set in the off-track number register j (step A).
4).

Then, the MR element 4 writes the measurement data at the center position D1 (in this case, since the measurement data was written at the center position D0 of the measurement track n, D1 = D0 =
0) is positioned off-track by the distance D given by the equation (4) (step A5).

That is, the write data center position D1 of the measured data is the distance D obtained by multiplying "-N" set in the off-track number register j by the off-track pitch amount d.
The MR element 4 is positioned off-track from (= D0 = 0) (see FIG. 6).

Here, the reproduction output level E of the measurement data read by the MR element 4 is measured by the head reproduction output measuring circuit 23, and the measured reproduction output level E is turned off according to the following equation (6). The apparent reproduction output area at the current head-off track position multiplied by the number of tracks j is added to the reproduction output area register SUM (step A7).

SUM = SUM + E × j (6) Here, “j ≧ N”, that is, the current off-track number (“−N” in this case) set in the off-track number register j is maximum off. It is determined whether or not the number of tracks N has been reached. If it is determined that the number of tracks N has not been reached, the number j of off-tracks this time is incremented by 1, and the position off-tracked by the distance D given by the equation (4) is again obtained. "in this case,
The MR element 4 is positioned at (−N + 1) × d ”, and the reproduction output level E thereof is measured (steps A8 → A9 →
A5, A6).

In this way, by repeating the processing of steps A5 to A9, as shown in FIGS. 5 and 6, the turning off from the maximum off-track distance (-N.times.d) with respect to the center position D0 of the measuring track n is performed. Track pitch amount d
The reproduction output level E by the MR element 4 is sequentially measured for each, and the apparent reproduction output area at each off-track position is added to the reproduction output area register SUM. Maximum off-track number N
The distance D from the center position D0 of the measuring track n
When the reproduction output level E is measured at a position off-tracked by (= N · d) and the reproduction output area is added, the reproduction output set in the reproduction output area register SUM is calculated according to the following equation (7). The total area is divided by the total number of measured tracks 2N of the reproduction output level E (steps A9 → A5, A6, A7, A8 → A10).

D2 = SUM / 2.N Equation (7) Then, according to the following equation (8), the off-track distance corresponding to the area center (A1 = A2) of the reproduction output is R / W.
It is calculated as the offset amount DOFS (step A1)
1).

DOFS = (D1−D0) + D2 (8) In this case, since the operation center position D1 of the measurement data is the center position D0 of the measurement track n, the R / W offset amount DOFS is (D2) Become.

Thus, when the R / W offset amount DOFS of the MR head 14 on the measurement track n is obtained by the optimum offset amount calculation circuit 25, the specific track n
Based on the R / W offset amount DOFS at the recording / reproducing head L and the azimuth angle θ at the specific track n, the effective recording position W0 and the effective reproducing position R0 of the head itself are deviated according to the above equation (3). The R / W offset amount DH is calculated. Further, the azimuth angle θ in each of the other tracks is substituted, and the MR head 14 which is optimum for all the tracks on the magnetic disk 11 is obtained.
R / W offset amount D.sub.OFS is calculated and set in the offset table 26.

On the other hand, the measurement process of the R / W offset amount DOFS of the MR head 14 in FIG. 7 is performed for three measurement tracks ni, nm, noi of the magnetic disk 11, for example, an inner track, an intermediate track and an outer track. Perform three R / W offset amounts DOFSi, DOFSm, DOFSo
Is linearly complemented to obtain the optimum R / W offset amount DOFS for all the disk tracks in the offset table 2
It may be set to 6.

As a result, the head positioning arithmetic circuit 24
Then, the MR set in the offset table 26
The MR element 4 in the MR head 14 is determined by correcting, for example, the read position of the MR head 14 with respect to the target track based on the optimum R / W offset amount DOFS according to each track position on the magnetic disk 11 of the head 14. The effective reproduction position R0 of is accurately positioned with respect to the center position of the target track.

In the first and second embodiments, the measurement data to be written in a specific measurement track n on the magnetic disk 11 corresponds to the width TWW of the recording head (TF) 1, 2, 3, 5 itself. However, as shown in FIG. 8, the width TWW of the recording head (TF) is
On the other hand, the measured data is written with a narrow width TW ', and the reproduction output level E is measured while the MR element 4 is off-tracked as described above, and the peak value Ep or the area center (A1 =
If the R / W offset amount DOFS is obtained from A2), the continuous reproduction output level E trajectory becomes steeper at each off-track position, and a more accurate R / W offset amount DOFS can be obtained. .

FIG. 8 is a diagram showing the writing / reading state of the measurement data accompanying the measurement processing of the R / W offset amount DOFS for the specific disk track of the MR head 14 in the magnetic disk device according to the third embodiment of the present invention. Is.

In this case, the measured data of the width TW 'narrower than that of the recording head (TF) is first written by writing the data of the head width TWW by positioning the MR element 4 at a certain position based on the servo data of the measurement track n. Then, the head is off-tracked and the data of the part of the width is erased by direct current, or the data of the part of the width is rewritten at a frequency much lower than the normal writing frequency. , Can be easily obtained.

Further, in the first, second and third embodiments, the measurement data written in the measurement track on the magnetic disk 11 is reproduced while the MR element 4 is off-track, and the reproduction output level E thereof is reproduced. The off-track amount from the write operation position of the measured data corresponding to the peak point or the center of area is determined as the R / W offset amount DOFS. For example, as shown in FIG. 11 is written in the track direction x in a predetermined width d by sequentially shifting in the rotational direction of the disk 11, and the measured data is sequentially reproduced without off-tracking the MR element 4 and written at any position. By comparing and measuring whether the reproduction output level E of the measured data becomes maximum, the head position positioned at the time of measurement and the reproduction output E become maximum. R / W offset amount DOFS of the MR head 14 depending on the distance from the measurement data writing position
Can be requested.

FIG. 9 is a diagram showing the writing / reading state of measurement data associated with the measurement process of the R / W offset amount DOFS of the MR head 14 in the magnetic disk device according to the fourth embodiment of the present invention.

In the first to fourth embodiments, R /
An area for measuring the W offset amount DOFS is provided on a specific track on the magnetic disk 11.
The magnetic disk 11 may be provided in a specific sector, or may be provided in a specific sector of each track, and for example, the R / W offset amount DOFS may be measured for each track.

Further, in each of the above-mentioned embodiments, the R / W offset amount DOF of the MR head 14 which is periodically measured.
By storing S in the offset table 26 and monitoring whether the change over time is excessively large, that is, whether it exceeds a certain threshold value, and detecting a head abnormality and issuing a warning, It is possible to prevent a situation in which a problem such as data loss occurs.

Thus, the R / W offset amount DOF
When the abnormality of the MR head 14 is detected based on the change of S with time, as described in the third embodiment, the narrow width T
More accurate R / W based on the measured data written in W '
It is preferable to apply the method of obtaining the offset amount DOFS because the detection sensitivity of the head abnormality becomes high.

[0099]

As described above, according to the magnetic disk device of the present invention, the effective recording position of the recording head with respect to the track direction of the magnetic disk and the reproducing head (MR element).
The recording / reproducing offset amount with respect to the effective reproducing position of is determined by measurement, and the positioning of the MR head is adjusted based on the measured recording / reproducing offset amount.
The head position can be adjusted to the optimum writing and reading position with respect to the target track.

Further, according to the head positioning adjusting method in the magnetic disk device according to the present invention, the measurement data is recorded on a specific track on the magnetic disk by the recording head of the MR head, and the measurement data recorded on this specific track. Is reproduced while the reproducing head (MR element) of the MR head is off-tracked, and the recording / reproducing offset amount is measured corresponding to the peak value of the reproducing signal at each off-track position. Since the positioning adjustment of the MR head is performed based on this, for example, when reading the recording data, the center position of the effective sensitivity of the MR element can be accurately positioned at the center position of the target track.

Therefore, even if the center position of the effective sensitivity is deviated due to variations in sensitivity distribution of individual MR heads or characteristic changes, the optimum write or read position with respect to the target track on the magnetic disk is always maintained. It is possible to position the head on the.

Further, according to another magnetic disk device of the present invention, when the change with time of the recording / reproducing offset amount periodically measured by the offset amount measuring means becomes a predetermined value or more, the user is notified. Is done,
It becomes possible to prevent problems such as data loss due to an abnormality of the MR head.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a principle of detecting a head position based on a servo burst signal in a head position information generating circuit of the magnetic disk device. FIG. 2A shows a servo burst signal recorded on a magnetic disk and an MR head. (B) shows the relative output relationship of the servo burst signal by the MR head (MR element), and (C) shows the MR head (MR element). The figure which shows the reproduction output characteristic of the servo burst signal with respect to a track direction position.

FIG. 3 is a graph showing the distance L between the recording / reproducing heads in the MR head of the magnetic disk device, the azimuth angle θ, and the R / W offset amount DH which is the deviation between the effective recording position W0 and the effective reproducing position R0 of the head itself. The figure which shows the relative relationship of R / W offset amount DOFS with respect to a data track.

FIG. 4 is a flowchart showing a measurement process of an R / W offset amount DOFS of a MR head with respect to a specific disk track in the magnetic disk device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a writing / reading state of measurement data accompanying the measurement processing of the R / W offset amount DOFS with respect to a specific disk track of the MR head in the magnetic disk device according to the first and second embodiments of the present invention. .

FIG. 6 is a graph showing the off-track amount D at the time of reproducing the measurement data accompanying the measurement process of the R / W offset amount DOFS for the specific disk track of the MR head in the magnetic disk device according to the first and second embodiments of the present invention. The figure which shows the change of reproduction | regeneration output level E.

FIG. 7 is a flowchart showing a measurement process of an R / W offset amount DOFS of a MR head with respect to a specific disk track in a magnetic disk device according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a writing / reading state of measurement data associated with a measurement process of an R / W offset amount DOFS with respect to a specific disk track of an MR head in a magnetic disk device according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a writing / reading state of measurement data associated with a measurement process of an R / W offset amount DOFS of an MR head in a magnetic disk device according to a fourth embodiment of the present invention.

10A and 10B are views showing the basic structure of an MR head, in which FIG. 10A is a sectional perspective view thereof, and FIG. 10B is a disk relative plan view thereof.

FIG. 11: Azimuth angle θ of the MR head with respect to the disk
FIG. 6 is a diagram showing a shift between a write track and a read track due to the above.

FIG. 12 is a diagram showing the up-down symmetry of the output waveform and the off-track characteristic of the output amplitude in the MR element.

[Explanation of symbols]

1 ... write upper pole, 2 ... write lower pole (MR upper shield), 3 ... write gap, 4 ... MR element, 5 ... coil, 6 ... MR lower shield, 11 ... magnetic disk, 11a ... disk retainer, 12 ... arm Axis, 13 ... Arm, 14 ... MR head (1-6), 15 ... VCM motor, 16 ... Electronic circuit, 21 ... R / W-IC, 22 ... Head position information generation circuit, 23 ... Head reproduction output measurement circuit, 24 ... Head positioning arithmetic circuit, 25 ... Optimal offset amount arithmetic circuit, 26 ... Offset table, 27 ... VCM drive circuit, x ... Track direction, y ... Disk running direction, E ... MR element reproduction output level, DOFS '... MR element R of the MR head at an arbitrary skew angle θ when the sensitivity center is on the axis of symmetry of the write head
/ W offset amount, DOFS ... M at arbitrary radius position (arbitrary skew angle θ)
R / R offset amount of R head, L ... Distance between recording / reproducing heads, θ ... Azimuth angle, DH ... R / W offset amount of head itself, W0 ... Effective recording position, R0 ... Effective reproducing position, TWW ... Recording head Write width, TWR ... Read head read width.

Claims (18)

[Claims] 1. A magnetic disk device using a magnetic head in which a recording head and a reproducing head are provided adjacent to each other, wherein a recording effective position of the recording head and a reproducing effective position of the reproducing head with respect to a track direction of the magnetic disk. An offset amount measuring means for measuring the recording / reproducing offset amount of the magnetic head, and a positioning adjusting means for adjusting the positioning of the magnetic head based on the recording / reproducing offset amount measured by the offset amount measuring means. Magnetic disk drive. 2. The magnetic disk has a specific track for measuring the recording / reproducing offset amount by the offset amount measuring means, and the offset amount measuring means reproduces the measurement data recorded on the specific track. 2. The magnetic disk device according to claim 1, wherein the magnetic disk device is an offset amount measuring means for reproducing while the head is off-track and measuring a recording / reproducing offset amount based on a reproduction signal at each off-track position. 3. The magnetic disk device according to claim 2, wherein the measurement data recorded on the specific track is measurement data recorded with a width narrower than a recording width of a recording head. 4. A magnetic disk device using a magnetic head in which a recording head and a reproducing head are provided adjacent to each other, wherein the reproducing head records measurement data recorded on a specific track on the magnetic disk by the recording head. And an offset amount measuring means for measuring the recording / reproducing offset amount corresponding to the peak value of the reproducing signal at each off-track position, and the recording / reproducing offset measured by the offset amount measuring means. A magnetic disk drive, comprising: a positioning adjusting means for adjusting the positioning of the magnetic head based on the amount. 5. A magnetic disk device using a magnetic head in which a recording head and a reproducing head are provided adjacent to each other, wherein the reproducing head records measurement data recorded in a specific track on the magnetic disk. And an offset amount measuring means for measuring a recording / reproducing offset amount corresponding to an area center of a reproduced signal at each off-track position, and a recording / reproducing offset measured by the offset amount measuring means. A magnetic disk drive, comprising: a positioning adjusting means for adjusting the positioning of the magnetic head based on the amount. 6. A track-by-track offset amount calculation means for obtaining a read / write offset amount individually corresponding to all tracks on the magnetic disk based on the read / write offset amount measured by the offset amount measuring means. 3. The positioning adjusting means is a positioning adjusting means for adjusting the positioning of the magnetic head based on the recording / reproducing offset amount of each track obtained by the offset amount calculating means for each track. The magnetic disk device according to claim 5. 7. The offset amount measuring means calculates a corresponding recording / reproducing offset amount on the basis of measurement data recorded on each of three specific tracks on an inner peripheral side track, an intermediate track, and an outer peripheral side track on a magnetic disk. An offset amount measuring unit for measuring, wherein the track-by-track offset amount calculating unit linearly complements each recording / reproducing offset amount on the inner side of the disc, the middle of the disc, and the outer side of the disc measured by the offset measuring unit. 7. The magnetic disk drive according to claim 6, which is track-by-track offset amount calculation means for obtaining a recording / reproducing offset amount individually corresponding to all tracks on the magnetic disk. 8. An offset table storage means for storing, as table data, a recording / reproducing offset amount of each track obtained by the track-by-track offset amount calculating means, wherein the positioning adjusting means has the offset table storing means. 8. The magnetic disk device according to claim 6, further comprising a positioning adjustment unit that adjusts the positioning of the magnetic head based on the recording / reproducing offset amount of each track stored in. 9. The magnetic disk has a specific sector for measuring the recording / reproducing offset amount by the offset amount measuring means, and the offset amount measuring means reproduces the measurement data recorded in the specific sector. 2. The magnetic disk device according to claim 1, wherein the magnetic disk device is an offset amount measuring means for reproducing while the head is off-track and measuring a recording / reproducing offset amount based on a reproduction signal at each off-track position. 10. The magnetic disk drive according to claim 9, wherein the measurement data recorded in the specific sector is measurement data recorded with a width narrower than the recording width of the recording head. 11. The offset amount measuring unit is an offset amount measuring unit for measuring a recording / reproducing offset amount corresponding to a peak value of a reproduced signal at each off-track position. Alternatively, the magnetic disk device according to claim 10. 12. The offset amount measuring unit is an offset amount measuring unit for measuring a recording / reproducing offset amount corresponding to an area center of a reproduced signal at each of the off-track positions. Alternatively, the magnetic disk device according to claim 10. 13. The offset amount measuring means reproduces a plurality of measurement data recorded by being shifted by a predetermined width in a track direction of a magnetic disk by positioning a reproduction head and reproducing the maximum measurement data from the plurality of measurement data. 2. The magnetic disk device according to claim 1, wherein the magnetic disk device is offset amount measuring means for measuring a recording / reproducing offset amount corresponding to a recording position of measurement data for measuring a reproduction signal. 14. The magnetic disk device according to claim 13, wherein the plurality of measurement data recorded by being shifted by a predetermined width in the track direction of the magnetic disk are measurement data recorded on a specific track. 15. The magnetic disk apparatus according to claim 13, wherein the plurality of measurement data recorded by being shifted by a predetermined width in the track direction of the magnetic disk are measurement data recorded in a specific sector. 16. A head positioning adjusting method in a magnetic disk device using a magnetic head in which a recording head and a reproducing head are provided adjacent to each other, wherein a specific track on the magnetic disk is recorded by the recording head of the magnetic head. The measurement data is recorded, and the measurement data recorded on the specific track is reproduced while the reproducing head of the magnetic head is off-track, and the recording / reproducing offset amount is set according to the peak value of the reproduction signal at each off-track position. A head positioning adjustment method in a magnetic disk device, characterized in that measurement is performed and the positioning of the magnetic head is adjusted based on the recording / reproducing offset amount. 17. A head positioning adjusting method in a magnetic disk device using a magnetic head in which a recording head and a reproducing head are provided adjacent to each other, wherein a specific track on the magnetic disk is recorded by the recording head of the magnetic head. The measurement data is recorded, and the measurement data recorded on this specific track is reproduced while the reproducing head of the magnetic head is off-track. A head positioning adjustment method in a magnetic disk device, characterized in that measurement is performed and the positioning of the magnetic head is adjusted based on the recording / reproducing offset amount. 18. A storage unit for storing a recording / reproducing offset amount periodically measured by the offset amount measuring unit, and a temporal change of the recording / reproducing offset amount accumulated in the accumulating unit is not less than a predetermined value. 10. The magnetic disk device according to claim 2, further comprising a notifying means for notifying the user of such a case.