JPH09102103A - Magnetic disk device having recording current control function and servo data recording method for magnetic disk device - Google Patents

Abstract

Kind Code: A1 A magnetic disk device having a recording current control function, in which, even when a track density is increased by using an MR head, a ratio of a fringe portion in servo data becomes large. Without getting good servo data. When servo data including a position error detection pattern is recorded on a magnetic recording surface of a magnetic disk,
The recording current supplied from the current source 23 by the current switching circuit 22 is switched to a low current value smaller than the current value for normal data recording, and the magnetic head (recording head HW) 15 is driven by this low recording current to drive the servo data. When recording the normal data, the recording current supplied from the current source 23 by the current switching circuit 22 is switched to a high current value sufficient for saturated recording on the magnetic recording surface of the magnetic disk 11, The magnetic head (recording head HW) 15 is driven by the recording current to record normal data.

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 having a recording current control function and a servo data recording method for the magnetic disk device.

[0002]

2. Description of the Related Art Generally, in a sector servo type magnetic disk device, a plurality of tracks are sequentially arranged in an annular shape from the inner circumference to the outer circumference of the magnetic disk.
A large number of servo areas SA and data areas DA are arranged alternately in the circumferential direction.

FIG. 5 is a diagram showing the structure of an in-track servo sector in a magnetic disk. Each track of the magnetic disk has a large number of servo sectors SS1 for each track.
, SS2, ..., SSn are assigned, and each servo sector SS1, SS2, ..., SSn is composed of a servo area SA and a data area DA.

Control data for positioning the magnetic head on the magnetic disk is recorded in the servo area SA. Based on the control data recorded in the servo area SA, magnetic data is recorded in a target servo sector SS. By moving and positioning the head, its servo sector SS
Writing (recording) data to the data area DA in
/ Reading can be done.

FIG. 6 shows the recording states of the control data for positioning the magnetic head in the servo area SA adjacent to each other.
It is a figure shown in the range of a track. Servo area SA is
AGC area 31a, erase area 31b, address area 31c, position error detection areas 32A, 32B, 3
The AGC area 31a consists of 2C and 32D.
A of sufficient length to stabilize the gain control operation by C
The GC stabilization pattern is recorded.

In the erase area 31b, an erase (no signal) pattern having a length that does not exist in the data portion is recorded and used to determine that the area is the servo area SA.
In the address area 31c, recording / writing of data in the data area DA of a desired track / sector by the magnetic head H is performed.
Address data indicating a track position and an index / sector position for reproduction is recorded. here,
The index indicates the sector that is the starting point in the track.

Position error detection areas 32A, 32B, 32
A position error detection pattern for holding the magnetic head H at the center position of the target track is recorded in C and 32D, and the upper half track or the lower side is recorded in the first and second areas 32A and 32B, respectively. The magnetization reversal patterns are alternately recorded on the half tracks, and the third and fourth areas 32 are recorded.
In C and 32D, a signalless pattern or a magnetization reversal pattern is alternately recorded on one track.

That is, when the target track on which the magnetic head H is positioned is, for example, n + 1 track, in the state where the magnetic head H is located at the center of the n + 1 track,
When passing through the position error detection areas 32A to 32D, signal levels of 50%, 50%, 0%, and 100% are sequentially detected, but when the magnetic head H is displaced by 10% in the direction of, for example, n tracks, The signal levels sequentially detected when passing through the same position error detection areas 32A to 32D are 40%, 60%, 10%, and 90%, respectively, and the direction and amount of the positional deviation are detected.

That is, by reading the position error detection pattern recorded in the position error detection areas 32A to 32D of the servo area SA by the magnetic head H, the position of the magnetic head H is detected and the target track center position. Head movement control is performed.

[0010]

FIG. 7 is a diagram showing a recording / reproducing state of normal data by a magnetoresistive head (MR head). FIG. 8 shows a magnetoresistive head (MR head).
FIG. 8 is a diagram showing a recording / reproducing state of servo data by the method.

Here, when data is recorded on the magnetic disk by the magnetic head, phenomena such as weakening of the magnetization and distortion occur at both ends of the recording head HW. Edge portions (fringe portions) F in which the data recording state is bad are recorded on the magnetic disk surfaces corresponding to both ends.

The width of the fringe portion F recorded corresponding to the both ends of the recording head HW is constant under the recording conditions (magnetic characteristics of the magnetic disk, ability of the recording head HW, flying height, recording current, etc.). If the recording current is large, the width of the fringe portion F is widened, although the recording is performed with a constant width if there is.

When data is recorded on the magnetic disk, a large current is used so as to obtain a good overwrite characteristic by sufficient saturation recording. This recording current includes the position error detection pattern. The same current value is set when recording the servo data.

Therefore, in both the recording of the servo data and the recording of the normal data, the fringe portion F having substantially the same width is formed on the magnetic disk surface corresponding to both ends of the recording head HW.
Will be recorded.

In this case, as shown in FIG. 7, normal data is recorded in a state where the recording head HW is accurately positioned at the center of the target track by reproducing the position error detection pattern (see FIG. 6). Therefore, the fringe portion F is recorded corresponding to only both end portions of each track. However, as shown in FIG. 8, the servo data including the position error detection pattern is moved by the recording head HW by a half track width. Since the fringe portion F is recorded after being recorded, the fringe portion F is also recorded at both end portions of each track and the center portion thereof.

When the normal data recorded as shown in FIG. 7 is read and reproduced, the reproducing head HR also accurately reproduces the position error detection pattern (see FIG. 6) at the center of the target track. Since the track width of the reproducing head HR in the MR head is narrower than the track width of the recording head HW, the fringe portion F recorded only at both ends of each track is read and reproduced. There is no such thing.

On the other hand, in order to move and position the magnetic head to a target track on the magnetic disk, when the servo data recorded as shown in FIG. 8 is read and reproduced, the reproducing head HR is set to an arbitrary position on the magnetic disk. The position error detection pattern is reproduced including the fringe portions F recorded at both ends of each track and the fringe portions F recorded at the center of each track. .

In this case, for the position error detection pattern,
There is no problem if the proportion of the fringe portion F is relatively small, but as the track width becomes narrower as the track density increases, the proportion of the fringe portion F becomes relatively larger, and therefore the position reproduced by the reproducing head HR. There is a problem in that the S / N ratio of the error detection signal is lowered and the linearity is deteriorated, which adversely affects the positioning accuracy of the magnetic head.

The present invention has been made in view of the above problems. For example, even when a high track density is achieved by using an MR head, the ratio of the fringe portion in the servo data does not increase and it is good. It is an object of the present invention to provide a magnetic disk device having a recording current control function that makes it possible to obtain various servo data and a servo data recording method for the magnetic disk device.

[0020]

That is, a magnetic disk device having a recording current control function according to claim 1 of the present invention comprises one or a plurality of rotated magnetic disks and a magnetic recording surface of the magnetic disk. To the magnetic recording surface of the magnetic disk, the data recording means for recording data on the magnetic recording surface of the magnetic disk by the magnetic head, and the magnetic recording surface of the magnetic disk by the data recording means. A recording current switching means for switching the recording current of the servo data to a current smaller than the recording current of the normal data when the servo data including the positioning information of the magnetic head is recorded, in order to reduce the area where the recording fringe occurs. And is provided.

That is, in the magnetic disk device having the recording current control function according to the first aspect, when recording the servo data including the positioning information, the recording current of the servo data becomes smaller than the recording current of the normal data. Since it can be switched, the width of the fringe portion included in the servo data becomes narrower, and even if the track density is increased, S
A position error detection signal with less deterioration of the / N ratio and deterioration of the straight line name can be obtained.

A magnetic disk device having a recording current control function according to a second aspect of the present invention is the magnetic disk device having the recording current control function according to the first aspect, wherein the recording current switching means is used for switching. The recording current of the servo data is set to different current values corresponding to each of the plurality of magnetic heads provided to face each of the plurality of magnetic recording surfaces.

That is, in the magnetic disk device having the recording current control function according to the second aspect, the recording current of the servo data which is switched by the recording current switching means is provided so as to face each of the plurality of magnetic recording surfaces. Since a different current value is set for each of the plurality of magnetic heads, the magnetic current of each is set to be smaller than the recording current of the normal data and to an appropriate recording current according to the performance individual difference of the plurality of magnetic heads. Servo data with few fringes is recorded on the recording surface.

A magnetic disk device having a recording current control function according to a third aspect of the present invention is the magnetic disk device having the recording current control function according to the first aspect, wherein switching is performed by the recording current switching means. The recording current of the generated servo data is set to a different current value for each zone corresponding to the radial direction of the magnetic recording surface.

That is, in the magnetic disk device having the recording current control function according to the third aspect, the recording current of the servo data switched by the recording current switching means is different for each zone corresponding to the radial direction of the magnetic recording surface. Since it is set to the current value, it is smaller than the recording current of normal data, and by the appropriate recording current according to each zone between the inner and outer circumferences of the magnetic recording surface, servo data with few fringe portions is recorded for each recording zone. Will be recorded.

According to a fourth aspect of the present invention, in a servo data recording method for a magnetic disk device, one or a plurality of rotated magnetic disks and a magnetic recording surface of the magnetic disk are provided so as to face each other. A servo data recording method for a magnetic disk device, comprising: a magnetic head; and a data recording means for recording data on a magnetic recording surface of the magnetic disk by the magnetic head. When the servo data including the positioning information of the magnetic head is recorded on the magnetic recording surface, the current is recorded with a current smaller than the recording current of the normal data.

That is, in the servo data recording method of the magnetic disk device according to the present invention, when the servo data including the magnetic head positioning information is recorded on the magnetic recording surface of the magnetic disk by the data recording means. Since the current is recorded with a current smaller than the recording current of the normal data, the width of the fringe portion included in the servo data is narrowed, and even if the track density is increased, S
A position error detection signal with less deterioration of the / N ratio and deterioration of the straight line name can be obtained.

A magnetic disk according to a fifth aspect of the present invention is characterized in that servo data including magnetic head positioning information is recorded with a recording current smaller than a recording current of normal data.

That is, in the magnetic disk according to the fifth aspect, the servo data including the positioning information of the magnetic head is
Since the recording is performed with a recording current smaller than the recording current of the normal data, the servo data with less fringe portion is reproduced.

[0030]

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 block diagram showing the configuration of an electronic circuit of a magnetic disk device having a recording current control function according to an embodiment of the present invention.

This magnetic disk device is composed of a magnetic disk 1
1 is provided. The magnetic disk 11 is rotated at a constant speed by a spindle motor (SPM) 12, and the spindle motor (SPM) 12 is an SPM.
It is driven by the rotation drive signal supplied from the driver 13.

The SPM driver 13 outputs a rotation drive signal for the spindle motor (SPM) 12 in response to a motor control signal supplied from a control unit (CPU + ASIC) 14.

At the position opposite to the magnetic recording surface of the magnetic disk 11, for example, a magnetoresistive head (M
A magnetic head 15 using an (R head) is disposed, and the magnetic head 15 is provided with a recording head HW and a reproducing head HR (see FIG. 7).

The magnetic head 15 is a magnetic disk 11.
On the magnetic recording surface of the voice coil motor (VC
M) 16 is moved to a target position corresponding to the radial direction of the magnetic disk 11, and the voice coil motor (VCM) 16 is driven by the rotation drive signal supplied from the VCM driver 17.

Then, the VCM driver 17 outputs a rotation drive signal for the voice coil motor (VCM) 16 in response to a motor control signal supplied from the control unit (CPU + ASIC) 14.

Here, the control unit (CPU + ASIC)
A ROM 18 is connected to 14, and a system program for causing the control unit 14 to execute various control processes is stored in the ROM 18 in advance.

That is, the rotation speed of the magnetic disk 11 and the moving position of the magnetic head 15 with respect to its magnetic recording surface are controlled by a motor control signal to the SPM driver 13 and the VCM driver 17 according to a system program stored in advance in the ROM 18. Controlled.

In addition, this magnetic disk device has a read / write
The light controller 19 is provided. The read / write controller 19 controls the recording and reproduction of data on the magnetic recording surface of the magnetic disk 11, and the write data for the magnetic disk 11 is driven by the head driver from the write driver circuit 20. By driving the magnetic head (recording head HW) 15 according to the signal, recording is performed at a target position on the magnetic recording surface of the magnetic disk 11.

The data recorded on the magnetic recording surface of the magnetic disk 11 is recorded on the magnetic head (reproducing head H).
It is read by R) 15 and given to the read / write controller 19 via the preamplifier 21.

Here, the recording current as a head drive signal for the magnetic head (recording head HW) 15 from the write driver circuit 20 is a current source whose output current value is switched by a current switching signal from the current switching circuit 22. 23, the switching operation of the recording current by the current switching circuit 22 is controlled by a recording current control signal from the control unit 14.

Hard disk controller (HDC) 2
Reference numeral 4 transfers the write data read from the buffer RAM 25 to the read / write controller 19 and also instructs the control unit 14 to write the write data, thereby setting the target on the magnetic disk 11. The magnetic head 15 is moved to the position, and a head drive signal corresponding to the write data is supplied to the magnetic head (recording head HW) to record the data at the target position.

Here, when the servo data including the position error detection pattern (see FIG. 6) is written, the current switching circuit 22 supplies the current from the current source 23 according to the recording current control signal from the control unit 14. The recording current is switched to a low current, and the servo data is sequentially recorded in accordance with the movement control of the magnetic head 15 on the magnetic recording surface of the magnetic disk 11 for each half track width.

When the normal data is written after the servo data is recorded on the magnetic recording surface of the magnetic disk 11, the current switching circuit 22 causes the current to change according to the recording current control signal from the controller 14. Source 2
The recording current supplied from 3 is switched to a high current, and normal data is recorded in accordance with the positioning control of the magnetic head 15 to the target position on the magnetic recording surface of the magnetic disk 11 based on the reproduction of the servo data.

In this case, the high current value of the recording current which is switched and set in association with the writing of the normal data is a current value for sufficiently saturated recording on the magnetic recording surface of the magnetic disk 11,
Further, the low current value of the recording current which is switched and set in accordance with the writing of the servo data is, for example, a current value which is about 70% of the high current value for the normal data recording.

At the low current value for recording the servo data,
Sufficient saturation recording is not performed on the magnetic recording surface of the magnetic disk 11, but since servo data need not be overwritten once it has been recorded, it is possible to record sufficiently accurate servo data, and moreover, the fringe portion. The width in which F (see FIG. 8) occurs can be suppressed.

On the other hand, the magnetic head (reproducing head HR) 15
The servo data read by the read / write controller 19 via the preamplifier 21 is supplied to the hard disk controller (HDC) 24 and also to the control unit 14 and used for positioning control of the magnetic head 15.

The magnetic head (reproducing head HR) 15
The normal data read by the read / write controller 19 via the preamplifier 21 is supplied to the hard disk controller (HDC) 24 and the buffer RAM 2
5 is stored.

Next, the operation of the magnetic disk device having the recording current control function having the above configuration will be described. First, when servo data including a position error detection pattern is recorded, the servo data to be recorded is stored in the buffer RAM 2 by the hard disk controller (HDC) 24.
5, and transferred to the read / write controller 19.

Then, the read / write controller 19
Supplies a head drive signal according to the magnetization reversal pattern corresponding to the servo data to the write driver circuit 20, and a write current according to the head drive signal is supplied from the current source 23 by the write driver circuit 20 to generate a magnetic field. The servo data is output to the head (recording head HW) 15 and recorded on the magnetic recording surface of the magnetic disk 11.

At the time of recording the servo data, the recording current supplied from the current source 23 is switched to a low current value by the switching signal from the current switching circuit 22, so that the servo data with less fringe portion F is recorded. Become so.

On the other hand, when recording normal data,
Normal data is a hard disk controller (HDC)
It is read from the buffer RAM 25 by 24 and transferred to the read / write controller 19.

Then, the read / write controller 19
Supplies a head drive signal according to the magnetization reversal pattern corresponding to the normal data to the write driver circuit 20, and a write current corresponding to the head drive signal is supplied from the current source 23 by the write driver circuit 20 to generate a magnetic field. Output to the head (recording head HW) 15,
Normal data is recorded on the magnetic recording surface of the magnetic disk 11.

At the time of recording of this normal data, the recording current supplied from the current source 23 is switched to a high current value by the switching signal from the current switching circuit 22, so that it is possible to perform the saturated recording sufficiently. High normal data will be recorded.

At the time of recording this normal data, the servo data already recorded on the magnetic disk 11 is transferred from the magnetic head (reproducing head HR) 15 to the printer amplifier 21.
Is played back to the read / write controller 19 via
The controller 14 controls the positioning of the magnetic head 15 on the magnetic disk 11 based on the reproduced signal of the servo data.

FIG. 2 is a diagram showing a magnetization pattern on the magnetic disk 11 and a reproduction waveform thereof by the magnetic disk device having the recording current control function. FIG. 2A shows the magnetization pattern recorded by a low recording current and the reproduction pattern. FIG. 6B is a diagram showing a reproduction waveform, and FIG. 6B is a diagram showing a magnetization pattern recorded by a high recording current and the reproduction waveform thereof.

That is, as shown in FIG. 2B, the magnetization pattern of the normal data recorded with a high recording current corresponds to both ends of the recording head HW and is magnetized in the data recording direction indicated by the arrow X. 2) and the width of the magnetic transition relatively widens, the peak of the reproduced waveform is dull and the output thereof is reduced. However, as shown in FIG. In the magnetization pattern of the recorded servo data, the residual magnetization hardly occurs and the width of the magnetic transition is clearly divided, so that the peak of the reproduced waveform is sharp and its output can be obtained at a high level.

Therefore, in the normal data recorded on each track of the magnetic disk 11 with a high recording current, the clear fringe portions F are recorded corresponding to both ends of the track, but the reproducing head HR is located at the center of the track. Since the data is read out by being positioned at, the fringe portion F does not adversely affect the normal data read and reproduction.

On the other hand, since the servo data recorded on the magnetic recording surface of the magnetic disk 11 with a low recording current is recorded with the fringe portion F being extremely small, for example, when reproducing the position error detection pattern, the magnetic head 11 At any position, the fringe portion F is not adversely affected and a good position error detection signal can be obtained.

Therefore, according to the magnetic disk device having the recording current control function having the above-mentioned structure, the magnetic disk 11
When recording the servo data including the position error detection pattern on the magnetic recording surface of, the recording current supplied from the current source 23 by the current switching circuit 22 is set to a low current value smaller than the current value for normal data recording. At the time of switching, the magnetic head (recording head HW) 15 is driven by this low recording current to record servo data, and when the normal data is recorded, the current source 2 is switched by the current switching circuit 22.
The recording current supplied from 3 is switched to a high current value for sufficiently saturated recording on the magnetic recording surface of the magnetic disk 11, and the high recording current drives the magnetic head (recording head HW) 15 to record normal data. The fringe portion F accompanying the recording of the servo data is significantly reduced. For example, even when the track width is narrowed as the track density is improved, the proportion of the fringe portion F is relatively small.
S / N of position error detection signal reproduced by reproducing head HR
It is possible to position the magnetic head with high accuracy without lowering the ratio or deteriorating the linearity.

In the above-described embodiment, the configuration in which one magnetic head 15 is used to record / reproduce data on one magnetic recording surface of the magnetic disk 11 has been described. Is equipped with a plurality of magnetic disks and a plurality of magnetic heads corresponding to the respective magnetic disks, or two magnetic heads are provided on one magnetic recording surface and the other magnetic recording surface of one magnetic disk. When the servo data is recorded, the recording current is made lower than the recording current of the normal data because the optimum recording current is slightly different depending on the performance individual difference of each magnetic head. Different optimum recording currents may be set for the respective magnetic heads.

FIG. 3 shows a state in which servo data is recorded in time division by one recording head HW1 and the other recording head HW2 on each of the one side magnetic recording surface and the other side magnetic recording surface of one magnetic disk 11. FIG.

That is, one recording head HW1 records servo data indicated by a solid line on one side of the magnetic disk 11, and in time division with this, the other recording head HW2 indicates a broken line on the other side of the magnetic disk 11. The indicated servo data is recorded, but the respective recording currents thereof are made lower than the current value for normal data recording, and furthermore, each recording head H
Set different current values according to the difference in performance between W1 and HW2. Specifically, the recording current is set to be smaller for a head that is prone to fringes.

As a result, even in a magnetic disk device having a plurality of magnetic recording surfaces and a plurality of corresponding magnetic heads, good servo data with few fringe portions F can be recorded on each magnetic recording surface. it can.

Further, in the above embodiment, when the servo data is recorded on the magnetic recording surface of the magnetic disk 11,
The case where the recording current is set to a current lower than the recording current of the normal data and the servo data is recorded with the same low recording current on the entire magnetic recording surface has been described.
Even if the same magnetic recording surface of one magnetic disk 11 is used,
Since the optimum recording current is slightly different depending on the position (zone) between the inner and outer circumferences, when recording servo data, the recording current should be lower than the recording current of normal data, and moreover, inside and outside the magnetic recording surface. Different optimum recording currents may be set for each zone between the circumferences. That is, when the recording density increases toward the inner circumference of the magnetic disk, it is necessary to set the recording current smaller. Further, in a zone where the head flying height is high, it is necessary to set the recording current to be small.

FIG. 4 is a diagram showing a division state of a plurality of zones Z1 to Z3 between inner and outer circumferences on the magnetic recording surface of one magnetic disk 11. That is, when servo data is recorded on one magnetic recording surface of one magnetic disk 11, the recording current is made lower than the current value for normal data recording, and moreover, between the inner and outer magnetic recording surfaces. Zone Z1,
The optimum different current value is set for each of Z2 and Z3.

As a result, even on one magnetic recording surface, good servo data with a small fringe portion F can be recorded in each of the recording zones Z1, Z2, Z3.

[0067]

As described above, according to the magnetic disk device having the recording current control function according to the first aspect of the present invention, when the servo data including the positioning information is recorded, the recording current of the servo data is Since the current can be switched to a current smaller than the recording current of the normal data, the width of the fringe portion included in the servo data becomes narrower, and even when a high track density is achieved, the S / N ratio is not deteriorated and the linear surname is less deteriorated. A position error detection signal can be obtained.

According to the magnetic disk device having the recording current control function of the second aspect of the present invention, the recording current of the servo data which is switched by the recording current switching means opposes each of the plurality of magnetic recording surfaces. Since a different current value is set for each of a plurality of magnetic heads that are provided, the recording current is less than the normal data recording current.
Moreover, servo data with less fringe portions can be recorded on each magnetic recording surface by an appropriate recording current according to the performance individual difference of a plurality of magnetic heads.

According to the magnetic disk device having the recording current control function of the third aspect of the present invention, the recording current of the servo data switched by the recording current switching means corresponds to the radial direction of the magnetic recording surface. Since a different current value is set for each zone to be recorded, the fringe portion is set for each recording zone with a recording current that is smaller than the recording current for normal data and that is appropriate for each zone between the inner and outer circumferences of the magnetic recording surface. The servo data with less data will be recorded.

Further, according to the servo data recording method of the magnetic disk device of the fourth aspect of the present invention, the servo data including the positioning information of the magnetic head with respect to the magnetic recording surface of the magnetic disk by the data recording means. Since the current is recorded with a current smaller than the recording current of the normal data, the width of the fringe portion included in the servo data is narrowed and the S / N ratio is increased even when the track density is increased. It becomes possible to obtain the position error detection signal with less deterioration of the ratio and deterioration of the straight line name.

According to the magnetic disk of claim 5 of the present invention, the servo data including the positioning information of the magnetic head is recorded with a recording current smaller than the recording current of the normal data. A small amount of servo data will be reproduced.

Therefore, according to the present invention, even if the track density is increased by using the MR head, for example, good servo data can be obtained without increasing the ratio of the fringe portion in the servo data. It is possible to provide a magnetic disk device having a recording current control function and a servo data recording method for the magnetic disk device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic circuit of a magnetic disk device having a recording current control function according to an embodiment of the present invention.

FIG. 2 is a diagram showing a magnetization pattern on a magnetic disk and a reproduction waveform thereof by a magnetic disk device having the recording current control function. FIG. 2A shows a magnetization pattern recorded by a low recording current and a reproduction waveform thereof. Figure, Figure (B)
FIG. 3 is a diagram showing a magnetization pattern recorded by a high recording current and a reproduction waveform thereof.

FIG. 3 shows one recording head HW1 for each of the one side magnetic recording surface and the other side magnetic recording surface of one magnetic disk.
FIG. 6 is a diagram showing a state in which servo data is recorded in time division by the other recording head HW2.

FIG. 4 is a diagram showing a divided state of a plurality of zones Z1 to Z3 between inner and outer circumferences on a magnetic recording surface of one magnetic disk.

FIG. 5 is a diagram showing a configuration of servo sectors in a track on a magnetic disk.

FIG. 6 is a diagram showing a recording state of control data for positioning a magnetic head in a servo area SA in a range of adjacent four tracks.

FIG. 7 is a diagram showing a recording / reproducing state of normal data by a magnetoresistive head (MR head).

FIG. 8 is a diagram showing a recording / reproducing state of servo data by a magnetoresistive head (MR head).

[Explanation of symbols]

 11 ... Magnetic disk, 12 ... Spindle motor (SPM), 13 ... SPM driver, 14 ... Control part (CPU + ASIC), 15 ... Magnetic head (HW, HR), 16 ... Voice coil motor (VCM), 17 ... VCM driver, 18 ... ROM, 19 ... Read / write controller, 20 ... Write driver circuit, 21 ... Preamplifier, 22 ... Current switching circuit, 23 ... Current source, 24 ... Hard disk controller (HDC), 25 ... Buffer RAM.

Claims (5)

[Claims] 1. One or a plurality of rotatable magnetic disks, a magnetic head provided so as to face the magnetic recording surface of the magnetic disk, and the magnetic head with respect to the magnetic recording surface of the magnetic disk. Data recording means for recording data and a recording current of the servo data when the servo data including the positioning information of the magnetic head is recorded on the magnetic recording surface of the magnetic disk by the data recording means. A magnetic disk device having a recording current control function, comprising: recording current switching means for switching to a current smaller than a recording current of normal data in order to reduce a region where fringes occur. 2. The recording current of the servo data switched by the recording current switching means is set to a different current value corresponding to each of the plurality of magnetic heads provided facing each of the plurality of magnetic recording surfaces. 2. A magnetic disk device having a recording current control function according to claim 1. 3. The recording current according to claim 1, wherein the recording current of the servo data switched by the recording current switching means is set to a different current value for each zone corresponding to the radial direction of the magnetic recording surface. A magnetic disk device having a current control function. 4. One or a plurality of rotatable magnetic disks, a magnetic head provided to face the magnetic recording surface of the magnetic disk, and the magnetic head with respect to the magnetic recording surface of the magnetic disk. A servo data recording method for a magnetic disk device, comprising: data recording means for recording data, wherein servo data including positioning information of the magnetic head with respect to a magnetic recording surface of the magnetic disk is recorded by the data recording means. A servo data recording method for a magnetic disk device, characterized in that a current smaller than a recording current of normal data is used for recording. 5. A magnetic disk, wherein servo data including magnetic head positioning information is recorded with a recording current smaller than a recording current of normal data.