JPH0963217A - Method for recording servo information on magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo information recording method capable of positioning a head with high accuracy without being influenced by a DC offset of a reproduced signal of information for positioning the head due to an edge dipole charge. SOLUTION: A burst pattern area consisting of plural burst patterns 101 arranged at prescribed intervals in the track widthwise direction is formed to be staggered with an adjacent burst pattern area in the track direction in a positioning area of a servo area. In addition, DC erase areas 102 of equalizing the magnetizing direction of the magnetic disk surface are formed opposite to both end edges of the individual burst patterns 101 in the track widthwise direction respectively, thereby recording the servo pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk servo information recording method for recording servo information (positioning data) for positioning a magnetic head at a desired position on a magnetic disk.

[0002]

2. Description of the Related Art Generally, in a magnetic disk device such as a hard disk device that records and reproduces data on a magnetic disk by using a magnetic head, a plurality of servo areas arranged discretely along a track direction on the magnetic disk. Further, there is a method in which servo information for positioning the magnetic head at a desired position on the magnetic disk is recorded in advance, and this servo information is read at the time of recording / reproducing data to position the magnetic head.

FIG. 9 shows a general structure of the servo area. The servo area 30 is provided, for example, for each sector on the magnetic disk, and includes an address AGC area 31, an erase area 32, a cylinder address area 33, a burst AGC area 34, a positioning data area 35, and a gap area 36. The role of each area is as follows.

First, in the address AGC area 31, the gain of an automatic gain control amplifier (hereinafter referred to as an AGC amplifier) for normalizing the amplitude of a reproduction signal is adjusted, and the subsequent detection of the erase area 32 and the cylinder address area 33. Guarantee the reproduction of. The start of the servo area is recognized in the erase area 32, and the cylinder address where the head exists is given in the cylinder address area 33. In the burst AGC area 34, the gain of the AGC amplifier is readjusted to ensure the extraction of positioning data from the burst pattern in the subsequent positioning data area 35. The positioning data area 35 includes a burst pattern that provides positioning data (head positioning information) for positioning the head at a desired position on the track. The gap area 36 is provided to absorb the rotational fluctuation of the magnetic disk.

When obtaining the positioning data from the positioning data area 35, the reproduction signal from the positioning data area 35 is passed through a filter capable of separating the signal from the burst pattern, and then the positioning data is extracted. Then, the head positioning control is performed based on this positioning data.

In a hard disk drive using an inductive head as a magnetic head, the positioning data area 35 is generally a plurality of burst pattern areas (four areas A, B, C and D in the example of the figure) as shown in FIG.
It consists of. Each burst pattern area A, B, C
And D, burst patterns in which continuous magnetization reversal patterns are recorded with a width of the track pitch Tp (indicated by vertical stripes in the figure) are arranged at predetermined intervals in the track width direction and are adjacent to each other in the track direction. The pattern regions are arranged so as to be displaced from each other by Tp or Tp / 2 in the track width direction. The alternate long and short dash line in FIG.
The center line of each track (hereinafter referred to as the track center) is shown.

In order to position the magnetic head 40 on the track center, the reproduction signal amplitudes a and b from the burst pattern areas A and B located between the adjacent track centers are calculated as (a-b) / (a + b). The position of the magnetic head 40 may be controlled so that the value of () becomes 0. On the other hand, in the burst pattern areas C and D located on the adjacent track centers, the magnetic heads 40 are adjacent to each other.
Even when the magnetic head 40 exists in a region crossing over one track, the position information of the magnetic head 40 can be obtained with good linearity.

FIGS. 11A, 11B and 11C show a method of forming the positioning data area 35 according to the prior art. 11A, 11B, and 11C, a method of forming the burst pattern areas A and B will be described, but the burst pattern areas C and D are formed in the same manner.

First, with the magnetic head 40 positioned at a desired position on the magnetic disk, a burst pattern forming a burst pattern area A with the width of the magnetic head 40 at a necessary portion as shown in FIG. 11A. In the burst pattern area B, direct current erasing (hereinafter referred to as DC erase) is performed in order to uniformly align the magnetization directions of the magnetic disk surface.

Next, as shown in FIG. 11B, the magnetic head 40 is moved in the track width direction by half the track pitch Tp, and then partially overlapped with the burst pattern in the burst pattern area A recorded immediately before the movement. While writing, align the phase and form the burst pattern area A again,
The other part performs DC erase.

Next, as shown in FIG. 11C, after the magnetic head 40 is further moved in the track width direction by half the track pitch Tp, a partial overwriting is performed in the burst pattern area A recorded immediately before the movement. The burst pattern area B is formed while performing. The burst pattern area B is arranged with a position shifted by the track pitch Tp in the track direction with respect to the burst pattern area A, and DC erase is performed on the portion other than the burst pattern.

By the above procedure, the burst pattern areas A and B having the burst pattern with the width of the track pitch Tp are formed. Hereinafter, by repeating the same procedure, the positioning data area as shown in FIG. 10 can be formed.

As described above, in the conventional servo information recording method, when the burst pattern area forming the positioning data area is formed, one of the two track edges of each burst pattern in the burst pattern area has a burst frequency. Signal is recorded, and the other edge is formed by DC erasing the portion outside the track pitch of the burst pattern.

[0014]

In recent years, as a reproducing element for reproducing information recorded at high recording density with high sensitivity, MR has been used.
The head is being put to practical use. When recording is performed using a head in which the MR head is used as a reproducing head and the inductive head is used as a recording head, which are integrated with each other (hereinafter referred to as a composite head), JLSu and K.Ju,
As described in IEEE Trans. Magn. MAG-25, 3384 (1989), edge dipole charges oriented in the track width direction occur on both sides of the recording track, and this edge dipole charge causes the reproduced signal to be reproduced. A shift in the reference level (center level) called the baseline shift is observed.

This edge dipole charge is shown in FIG.
This also occurs when DC erase is performed as shown in (a). The portion with a thick arrow in FIG. 12A is DC.
It is an erase region, and thin arrows with + and-signs on the upper and lower sides of the figure represent the edge dipole charge. FIG.
FIG. 12A shows a general configuration of the inductive recording head in the composite head as seen from the magnetic disk surface side.
Are shown in correspondence with. This inductive recording head
The lower pole 41 on the leading side and the upper pole 42 on the trailing side form a recording gap 43. When reproducing with the MR reproducing head (not shown) in the composite head, the magnetic flux from the edge dipole charge is MR of the MR reproducing head.
If it is taken into the film, a DC-like offset (hereinafter referred to as DC offset) is generated in the reproduction signal.

FIG. 13A shows a case where the positioning data area 35 is formed on the magnetic disk by using the inductive recording head in the composite head by the same method as in the case of using the conventional inductive head. As described above, the edge dipole charge as described above appears at the edge of the portion (hatched portion) overwritten by the DC erase in the positioning data area 35. The edge dipole charge is indicated by an arrow with + and-signs on both sides, as in FIG.

From this positioning data area 35 to M
When reproducing the head positioning information with the R reproducing head 50, the MR reproducing head 50 is reproduced in a state in which the MR reproducing head 50 is located on the track center indicated by the alternate long and short dash line, that is, in a position straddling the track edge (edge in the track width direction) of the burst pattern. To obtain the signal, the magnetic flux from the edge dipole charge is taken into the MR film under the influence of the edge dipole charge on the track edge overwritten by the DC erase. As a result, the reproduction signal of the head positioning information has a burst pattern area A as shown in FIG.
DC overwritten by the DC erase in
Has an offset.

Here, the polarity of DC erase, that is, DC
When the magnetization direction of the magnetic disk surface in the erase area is reversed, the polarity of the edge dipole charge is also reversed, so that a DC offset occurs on the side opposite to the reference line in FIG. Strictly speaking, even at the track edge of the burst pattern in the burst pattern area B,
Edge dipole charges having different polarities appear at each magnetization reversal of the continuous magnetization reversal pattern forming the burst pattern, but the edge dipole charges are canceled in the burst pattern in the burst pattern area B as a whole, so that the DC offset here is generated. Can be ignored.

Such a DC offset gives a DC offset to the positioning data, which naturally has an unfavorable influence on the track following of the composite head.

The present invention provides a servo information recording method for a magnetic disk device which enables highly accurate head positioning without being affected by the DC offset of the reproduction signal of the head positioning information caused by the above-mentioned edge dipole charge. The purpose is to do.

[0021]

In order to solve the above problems, the present invention determines the polarity of the edge dipole charge experienced when the magnetic head passes through the positioning data area of the servo area by the control band of the head positioning control system. By changing the frequency at a sufficiently higher frequency, the head positioning control system does not respond to the DC offset generated in the reproduction signal of the head positioning information due to the edge dipole charge.

That is, in the first servo information recording method according to the present invention, a burst pattern area composed of a plurality of burst patterns arranged in the servo area at a predetermined interval in the track width direction is provided between adjacent burst pattern areas in the track direction. Servo information is recorded by forming the DC erase areas, which are formed at different positions from each other and face the edges at both ends of each burst pattern in the track width direction and in which the magnetization direction of the magnetic disk surface is uniform. It is characterized by In this case, it is desirable that the magnetization direction of the magnetic disk surface in each DC erase area be the same.

In the first servo information recording method, the direction of the edge dipole charge caused by the DC erase is reversed in each burst pattern area, and the DC offset of the reproduction signal of the head positioning information generated by the edge dipole charge is generated. The direction of is also reversed for each burst pattern area. That is, the DC offset component appears as a signal that changes for each burst pattern area. Since the control band of the head positioning control system is sufficiently lower than the signal band of the DC offset component, the head positioning control system does not follow this DC offset component, and the head is correctly positioned on the desired positioning line.

Further, in the second servo information recording method according to the present invention, a burst pattern area composed of a plurality of burst patterns arranged in the servo area at a predetermined interval in the track width direction is provided between adjacent burst pattern areas in the track direction. It is characterized in that the servo information is recorded by forming the patterns at different positions from each other and by forming individual burst patterns only by recording signals of burst frequency. In this case, it is desirable to perform DC erasing on the entire surface of the magnetic disk in advance so that the magnetization direction of the magnetic disk surface is aligned in one direction before recording the servo information.

In the second servo information recording method, each burst pattern is formed only by recording the frequency of the burst signal, unlike the conventional method of forming one track edge by DC erase. There is no DC offset due to edge dipole charge as in the case where one track edge of the burst pattern is formed by DC erase, or even if it occurs, it is the same as in the case of the first servo information recording method described above. Further, since the direction of the DC offset is reversed for each burst pattern area, head positioning can be performed without being affected by this DC offset.

Further, according to the third servo information recording method of the present invention, a burst pattern area composed of a plurality of burst patterns arranged in the servo area at a predetermined interval in the track width direction is provided between adjacent burst pattern areas in the track direction. A DC erase area is formed by shifting the positions of the burst patterns and facing at least one edge in the track width direction of each burst pattern, and the magnetization direction of the magnetic disk surface is uniform, and the magnetic field in the DC erase area is formed. Servo information is recorded by reversing the magnetization direction of the disk surface in the adjacent servo areas.

In the third servo information recording method, the direction of the edge dipole charge caused by the DC erase is reversed for each servo area, and the DC offset of the reproduction signal of the head positioning information generated by the edge dipole charge is generated. The direction is also reversed for each servo area, and the DC offset component appears as a signal that changes for each servo area. Also in this case, the former is sufficiently lower than the latter in the control band of the head positioning control system and the signal band of the DC offset component which changes for each servo area.
The head positioning control system does not follow the C offset component,
The head is correctly positioned on the desired positioning line.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing magnetization patterns of burst pattern areas A and B in a positioning data area according to an embodiment of the present invention, where a dashed line represents a track center and Tp represents a track pitch. . As shown in the figure, in the burst pattern areas A and B, a burst pattern 101 (in the figure) is formed of a continuous magnetization reversal pattern having a track pitch Tp including information for positioning the composite head 9 (positioning data). ,
The shaded areas) and the DC erase areas 102 (arrow areas in the drawing) having a width of the track pitch Tp are alternately arranged, and the track pattern areas A and B are T in the track width direction.
The positions are shifted by p. Although not shown,
In the other set of burst pattern areas C and D as well as the burst pattern areas A and B, the burst patterns and the DC erase areas are alternately arranged in the track width direction and the positions are shifted by Tp in the track width direction. It has been done.

The servo information recording method according to this embodiment is
In the positioning data area of the servo area, the DC erase area 102 is formed so as to face both track edges (edges at both ends in the track width direction) of the burst pattern 101 forming the burst pattern area. One edge is formed only by recording a signal of the burst frequency, which is different from the conventional method of forming a DC erase area facing the other track edge. In other words, the method of forming both track edge portions of each burst pattern is the same in this embodiment.

When the positioning data area is formed in this way, when the polarity of the DC erase, that is, the magnetization direction of the magnetic disk surface in the DC erase area 102 is the same, the direction of the edge dipole charge caused by the DC erase is the burst pattern. The direction is reversed for each region, and the direction of the DC offset of the reproduced signal of the positioning data generated by the edge dipole charge is also reversed for each burst pattern region. Therefore, when the head positioning control is performed using the positioning data, the control band of the head positioning control system is sufficiently lower than the band of the signal that changes for each burst pattern area, so the head positioning control system follows this DC offset component. Not, the head will be correctly positioned on the desired positioning line, ie the track center of the desired track.

FIG. 2 is a block diagram showing the configuration of the servo information recording apparatus in this embodiment. Magnetic disk 1
Prior to recording servo information (servo pattern) on the magnetic disk 1, an index and a servo signal are recorded on a predetermined track (hereinafter referred to as a servo clock track) on the magnetic disk 1 by using a clock head 2 and a clock head recording / reproducing amplifier 3. Record the clock for use. The index and servo signal clock are generated by the index & servo signal clock generation circuit 4 and serve as a timing reference for forming a servo pattern.

At the time of servo pattern recording, the index for obtaining the recording timing of the servo pattern and the clock for the servo signal are reproduced from the servo clock track by the clock head 2, and these are amplified by the clock head recording / reproducing amplifier 3 to produce the index &. It is sent to the servo signal clock separation circuit 5. The index & servo signal clock separation circuit 5 separates and generates an index signal and a servo signal clock from the reproduction signal from the clock head 2 and sends them to the servo pattern generation circuit 6.

In the servo pattern generation circuit 6, a series of servo pattern recording signals shown in FIG. 9 are generated based on the timing of the index signal and the servo signal clock. At this time, the burst pattern in the positioning data area is generated based on the servo signal clock.

A series of servo pattern recording signals formed by the servo pattern generating circuit 6 are sent to a recording / reproducing amplifier 8 provided on the magnetic disk device side, and an inductive recording head in the composite head 9 causes a magnetic disk to be recorded. 1 is recorded as a servo pattern. At the time of recording the servo pattern, a head position control circuit 11 generates a head position control signal in accordance with the head position detected by a head position detection circuit 10 configured by, for example, a laser length measuring machine, and the head position control signal causes an actuator driver. The desired servo pattern is recorded on the entire circumference of the magnetic disk 1 while operating the actuator 12 to send the composite head 9 in the radial direction of the magnetic disk 1 by the actuator 13.

Here, as shown in FIG. 4, a composite head 9 is used, an inductive recording head 21 in the composite head 9 previously records one track with a burst frequency signal, and the recorded track is recorded. A profile of a reproduction signal obtained by reproducing by the reproducing MR head 22 in the composite head 9 while the composite head 9 is being moved in the radial direction of the magnetic disk 1 by the actuator 13 (hereinafter,
Off-track profile). The full width at half maximum of the off-track profile at this time is defined as the recording track width (= X). Regarding the movement of the composite head 9, the recording track width X is also used in addition to the track pitch. The value of the recording track width X may be adjusted depending on the situation.

FIG. 3 shows a block diagram of a data reproducing apparatus for reproducing data from the magnetic disk 1 by using the servo pattern thus recorded. Magnetic disk 1
The reproduction signal reproduced by the MR reproducing head in the composite head 9 from above is amplified by the recording / reproducing amplifier 8 and then sent to the servo area / data area separating circuit 14, the data reproducing circuit 15 and the burst signal separating filter 16. To be
The reproduction signal recognized as a signal in the data area by the servo area / data area classification circuit 14 is demodulated in the data reproduction circuit 15 and is sent out as reproduction data. The reproduction signal recognized as the signal in the servo area by the servo area / data area classification circuit 14 is input to the burst signal separation filter 16 having the characteristics of a low pass filter or a band pass filter, and the reproduction signal of the burst pattern is extracted. By being sent to the circuit 17 for
It is used for position control of the composite head 9.

Next, the procedure for recording the servo pattern shown in FIG. 1 will be described with reference to FIG. The recording track width X by the inductive recording head 21 in the composite head 9 is
It is assumed that X ≧ Tp / 2 (Tp: track pitch) is satisfied. A desired track pitch Tp is divided into upper and lower parts from the center, and the first burst pattern 103 is recorded at a position across the area K having a width of one Tp / 2. Next, the second burst pattern 104 is recorded at a position straddling the other region L having a width of Tp / 2 so as to have the same phase as the first burst pattern 103. After that, the position M where the outer edges of the regions K and L and the edge of the composite head 9 meet
And the composite head 9 is moved to the position N, and then D
C erase is performed to form the DC erase region 102.

The procedure for forming the burst pattern area A is as follows: K area recording → L area recording → M area DC erase →
If it is referred to as N area DC erase (here, “recording” means recording a signal of a burst frequency to form a burst pattern), the procedure for forming the burst pattern area A is as follows. In addition, various procedures as listed below can be used.

K area recording-> L area recording-> N area DC erase-> M area DC erase-L area recording-> K area recording-> M area DC erase-> N area DC erase-L area recording-> K area recording-> N area DC erase → M area DC erase ・ K area recording → M area DC erase → L area recording → N area DC erase ・ L area recording → N area DC erase → K area recording → M area DC erase Similarly, burst pattern area B Can also be formed using various procedures as described below.

P area recording-Q area recording-R area DC erase-S area DC erase-P area recording-Q area recording-S area DC erase-R area DC erase-Q area recording-P area recording-R area DC erase-> S area DC erase-Q area recording-P area recording-S area DC erase-R area DC erase-P area recording-R area DC erase-Q area recording-S area DC erase-Q area recording-S area DC erase → P area recording → R area DC erase Burst pattern area C and burst pattern area D
The procedure for forming the same is the same as the procedure for forming the burst pattern area A and the burst pattern area B. In this case, for example, a set of the first burst pattern in the burst pattern area A and the second burst pattern in the burst pattern area D, which can be recorded without moving the composite head 9, is recorded in these areas. It is also possible to prioritize. In a position other than the burst pattern, if the burst pattern is not erased, DC erase may be performed, or the recording current may be cut off and nothing may be performed.

Here, when the DC erase is performed on both track edges of each burst pattern, if the polarities of all the DC erases are matched, for example, the N region in the burst pattern region A and the R region in the burst pattern region B will be displayed. In addition, the directions of the edge dipole charges generated in the two regions in contact with a certain positioning line (track center) are opposite to each other, and D caused by this is generated.
The C offsets also face in opposite directions. As described above, the control band of the head positioning control system is sufficiently lower than the band of the signal that changes for each servo pattern area.
It does not follow this DC offset component. Therefore, the composite head 9 can be correctly positioned on the positioning line without being affected by the DC offset generated by the edge dipole charge.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
7 shows magnetization patterns of burst pattern areas A, B, C and D of the positioning data area 35 in the embodiment of FIG. The method of forming the burst pattern 101 including information for head positioning is the same as the conventional method described in FIG. According to the conventional method, the DC erase region 102 faces one track edge of each burst pattern 101, that is, the lower track edge in the figure in this example.
Is formed.

In the present embodiment, after each burst pattern 101 is formed in this way, a new DC erase is performed facing the other track edge of each burst pattern 101, that is, the upper track edge in the figure,
A DC erase area 102 is formed. In the DC erase area 102, a portion with a dot pattern is a DC erase area formed by a conventional method, and a portion without a dot pattern is a DC newly formed according to this embodiment.
Erase area.

The polarities of the DC erase are all the same as in the first embodiment. Also in this embodiment, the off-track profile is measured in advance to obtain the recording track width, but the value of the recording track width may be adjusted depending on the situation.

Also in this embodiment, since the DC erase area 102 is formed so as to face both track edges of each burst pattern 101, the DC offset caused by the edge dipole charge is generated as in the first embodiment. Can solve problems.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention.
7 shows magnetization patterns of burst pattern areas A, B, C and D in the positioning data area 35 in the embodiment of FIG.

In the present embodiment, the recording track width X is obtained in advance from the above-mentioned off-track profile.
When forming the burst pattern area A, first, the first burst pattern 105 is formed by recording a signal of the burst frequency at a desired position by the head. After that, the head is moved by the distance x to record the signal of the burst frequency, so that the second burst pattern 106 is formed so as to partially overlap with the first burst pattern 105. As a result, each burst pattern in the burst pattern area A is formed. Burst patterns are similarly formed in the burst pattern areas B, C, and D.

As described above, in this embodiment, since each burst pattern is formed only by recording the signal of the burst frequency, the DC erase for forming the track edge is unnecessary. That is, by performing DC erase on the entire surface of the magnetic disk in advance, DC erase after the burst pattern formation is unnecessary. When forming the burst pattern areas A, B, C and D,
The DC erase may be performed for each part other than the burst pattern on the same track.

According to the present embodiment, when reproducing the positioning data from any burst pattern, a DC offset due to the edge dipole charge does not occur in the reproduced signal, so that the self-recording / reproducing with the inductive head is performed. High-precision head positioning similar to that described above can be realized by using a composite head.

(Fourth Embodiment) FIG. 8 shows the magnetization patterns of the burst pattern areas A and B in the positioning data area 35 in this embodiment. As shown in the figure, in the burst pattern areas A and B, burst patterns 201, which are continuous magnetization reversal patterns each having a track pitch width including information (positioning data) for positioning the composite head 9, are arranged at predetermined intervals. The track pattern areas A and B are arranged and are displaced from each other by a track pitch in the track width direction. Also, a DC erase area 202 is formed facing the one track edge of the burst pattern 201 and indicated by a thick arrow of the track pitch. Although not shown, in the other set of burst pattern areas C and D, it is assumed that the burst pattern and the DC erase area are formed similarly to the burst pattern areas A and B.

The method of forming the burst pattern areas A, B, C and D in each positioning data area 35 is basically the same as the conventional method as described above, but in this embodiment, the DC erase area 202 is used. The magnetic recording medium is characterized by reversing the magnetization direction of the magnetic disk surface between adjacent servo areas (positioning data areas). That is, the magnetization directions of the magnetic disk surface in the DC erase area 202 are opposite to each other in the nth positioning data area and the (n + 1) th positioning data area, as shown in FIG.

Positioning regions 3 adjacent to each other in this way
When the magnetization direction of the magnetic disk surface in the DC erase area 202 is reversed at 5, the direction of the edge dipole charge due to the DC erase becomes opposite for each positioning area, that is, for each servo area, as shown in FIG. ,
The direction of the DC offset of the reproduced signal of the positioning data generated by the edge dipole charge is also reversed for each servo area. Note that, in FIG. 8, the edge dipole charge is +, on both upper and lower sides of the figure, as in FIGS. 12 and 13.
It is indicated by a small arrow with a minus sign.

Therefore, when the head positioning control is performed using the positioning data, the control band of the head positioning control system is sufficiently lower than the band of the signal changing for each servo area. Will not follow and the head will be correctly positioned on the desired positioning line, ie the track center of the desired track.

This action will be described using mathematical expressions. Positioning data, which is servo information for head positioning obtained in this embodiment, is represented by the following equation (1) in the n-th servo area (positioning data area).

P (n) = A + OF-B (1) P (n): Positioning data A: Reproduction signal from burst pattern area A B: Reproduction signal from burst pattern area B OF: Reproduction from burst pattern area A Offset added to the signal On the other hand, in the next n + 1-th servo area (positioning data area), the positioning data P (n + 1) is expressed by the following equation (2).

P (n + 1) = A-OF-B (2) Here, the positioning data P (n + 1) is redefined as the following expression (3), and head positioning control is performed based on this information.

P ′ (n + 1) = {P (n + 1) + P (n)} / 2 (3) From Expression (3), it is possible to obtain the positioning data in which the DC offset amount caused by the edge dipole charge is canceled. I understand.

The configuration of the servo information recording apparatus in this embodiment is basically the same as that of FIG. 2, but the function of the servo pattern generation circuit 6 is slightly different. That is, in the present embodiment, when the servo pattern generation circuit 6 generates a series of servo pattern recording signals shown in FIG. 9 based on the timing of the index signal and the clock for the servo signal, a pattern other than the burst pattern in the positioning data is generated. As for the DC erase signal, a signal is generated such that the direction of the recording current is inverted for each servo area.

On the other hand, the data reproducing apparatus for reproducing data from the magnetic disk 1 using the servo pattern thus recorded is basically the same as that shown in FIG. Here, the control band of the head positioning control system is set sufficiently lower than the band of the signal that changes for each servo area. For example, if the number of servo areas on the magnetic disk 1 is 100 per one rotation of the disk and the rotation frequency of the magnetic disk 1 is 60 Hz, the sampling frequency at which servo information for head positioning is obtained is 6 kHz. Therefore, the control band is set to about 600 Hz or less. By thus setting the control band sufficiently lower than the sampling frequency, the head positioning control system does not follow the DC offset component, and the head is positioned on the desired positioning line.

In the above-described embodiment of the present invention, the case of the sector servo system has been described. However, the servo information recording method according to the present invention also applies to the case where the servo patterns are densely formed like the servo surface servo system. Applicable.

[0061]

As described above, according to the present invention, the magnetic head is positioned at a desired position on the magnetic disk in a plurality of servo areas discretely arranged along the track direction on the magnetic disk. When recording servo information for, to form a burst pattern area consisting of a plurality of burst patterns arranged at a predetermined interval in the track width direction in the servo area, are formed by shifting the positions between adjacent burst pattern areas in the track direction, In addition, DC erase areas having uniform magnetization directions on the magnetic disk surface are formed facing the edges of both ends of each burst pattern in the track width direction, and more preferably, the magnetization directions on the magnetic disk surface in each DC erase area are formed. By making them the same, the magnetic head will experience when passing the positioning data area of the servo area. The polarity of the edge dipole charge can be changed at a frequency sufficiently higher than the control band of the head positioning control system, and the head positioning control is performed with respect to the DC offset generated in the reproduction signal of the head positioning information due to the edge dipole charge. The system can be made unresponsive.

Further, according to the present invention, after the servo erase is performed, DC erase is performed to align the magnetization direction of the magnetic disk surface in one direction, and then a plurality of burst patterns are arranged in the servo area at predetermined intervals in the track width direction. Edge pattern dipole charging is also performed by forming the burst pattern areas that are adjacent to each other in the track direction by offsetting each other, and forming each burst pattern only by recording a signal of the burst frequency. It is possible to prevent the head positioning control system from responding to the DC offset generated in the reproduction signal of the head positioning information due to the above.

Further, according to the present invention, when the servo information is recorded, the burst pattern areas composed of a plurality of burst patterns arranged in the servo area at a predetermined interval in the track width direction are positioned with respect to each other between the burst pattern areas adjacent in the track direction. A DC erase area is formed so as to be offset and facing at least one edge in the track width direction of each burst pattern, and a uniform magnetization direction of the magnetic disk surface is formed, and further, a DC disk area in the DC erase area is formed. By reversing the magnetization direction in the adjacent servo areas, it is possible to prevent the head positioning control system from responding to a DC offset similarly generated in the reproduction signal of the head positioning information due to the edge dipole charge.

Therefore, according to the present invention, it is possible to perform highly accurate head positioning without being affected by the DC offset of the reproduction signal of the head positioning information caused by the edge dipole charge.

[Brief description of drawings]

FIG. 1 is a diagram showing a magnetization pattern in a burst pattern area on a positioning data area according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a servo information recording device according to the present invention.

FIG. 3 is a block diagram showing a configuration of a data reproducing device according to the present invention.

FIG. 4 is a diagram showing an off-track profile.

FIG. 5 is a view for explaining the servo information recording method according to the same embodiment.

FIG. 6 is a diagram for explaining a servo information recording method according to a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a servo information recording method according to a third embodiment of the present invention.

FIG. 8 is a diagram for explaining a servo information recording method according to a fourth embodiment of the present invention.

FIG. 9 is a diagram for explaining the configuration of a general servo area.

FIG. 10 is a diagram showing a configuration of a conventional positioning data area.

FIG. 11 is a diagram for explaining a conventional method of forming a burst pattern in a positioning data area.

FIG. 12 is a diagram for explaining the principle of generation of edge dipole charge.

FIG. 13 is a diagram for explaining the principle of DC offset generation due to edge dipole charge.

[Explanation of symbols]

 1 ... Magnetic disk 2 ... Clock head 3 ... Clock head recording / reproducing amplifier 4 ... Index & servo signal clock generating circuit 5 ... Index & servo signal clock separating circuit 6 ... Servo pattern generating circuit 8 ... Recording / reproducing amplifier 9 ... Composite Head 10 ... Head position detection circuit 11 ... Head position control circuit 12 ... Actuator driver 13 ... Actuator 14 ... Servo area Data area sorting circuit 15 ... Data reproduction circuit 16 ... Burst signal separation filter 17 ... Burst signal separation filter 18 ... Servo area 21 ... Inductive recording head 22 ... MR reproducing head 31 ... Address AGC area 32 ... Erase area 33 ... Cylinder address code area 34 ... Burst AGC area 35 ... Positioning data area 36 ... Gap area 40 ... Inductive recording head 41 ... Lower pole 42 ... Upper pole 43 ... Recording gap 101 ... Burst pattern 102 ... DC erase area 103 ... First burst pattern 104 ... Second burst pattern 105 ... First burst pattern 106 ... 2 burst pattern 201 ... burst pattern 202 ... DC erase area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Yamada 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center

Claims (5)

[Claims] 1. A servo of a magnetic disk for recording servo information for positioning a magnetic head at a desired position on a magnetic disk in a plurality of servo areas discretely arranged along a track direction on the magnetic disk. In the information recording method, in the servo area, a burst pattern area formed of a plurality of burst patterns arranged at a predetermined interval in the track width direction is formed by displacing positions between adjacent burst pattern areas in the track direction, and Servo of a magnetic disk, characterized in that the servo information is recorded by forming a DC erase area in which the magnetization direction of the magnetic disk surface is uniform, facing the edges at both ends of the burst pattern in the track width direction. Information recording method. 2. A servo of a magnetic disk for recording servo information for positioning a magnetic head at a desired position on a magnetic disk in a plurality of servo areas discretely arranged along a track direction on the magnetic disk. In the information recording method, in the servo area, a burst pattern area formed of a plurality of burst patterns arranged at a predetermined interval in the track width direction is formed by displacing positions between adjacent burst pattern areas in the track direction, and DC erase areas having uniform magnetization directions on the magnetic disk surface are formed facing edges of both ends of the burst pattern in the track width direction, and the magnetization directions on the magnetic disk surface in the respective DC erase areas are the same. A servo information recording method for a magnetic disk, characterized by recording servo information. 3. A servo of a magnetic disk for recording servo information for positioning a magnetic head at a desired position on the magnetic disk in a plurality of servo areas discretely arranged along the track direction on the magnetic disk. In the information recording method, in the servo area, a burst pattern area composed of a plurality of burst patterns arranged at a predetermined interval in the track width direction is formed by displacing positions between adjacent burst pattern areas in the track direction, and The servo information recording method for a magnetic disk, wherein the burst pattern is formed only by recording a signal having a burst frequency to record the servo information. 4. A servo of a magnetic disk for recording servo information for positioning a magnetic head at a desired position on a magnetic disk in a plurality of servo areas discretely arranged along a track direction on the magnetic disk. In the information recording method, after performing a DC erase to align the magnetization direction of the magnetic disk surface in one direction, a track is formed in the servo area by a burst pattern area including a plurality of burst patterns arranged at a predetermined interval in a track width direction. A magnetic disk characterized in that the servo information is recorded by forming the respective burst patterns by shifting the positions of the burst pattern areas adjacent to each other in the direction, and by forming the individual burst patterns only by recording the signals of the burst frequency. Servo information recording method. 5. A servo of a magnetic disk for recording servo information for positioning a magnetic head at a desired position on a magnetic disk in a plurality of servo areas discretely arranged along the track direction on the magnetic disk. In the information recording method, in the servo area, a burst pattern area formed of a plurality of burst patterns arranged at a predetermined interval in the track width direction is formed by displacing positions between adjacent burst pattern areas in the track direction, and A DC erase area is formed facing at least one edge in the track width direction of the burst pattern, and the magnetization direction of the magnetic disk surface is uniform, and the servo area is adjacent to the magnetization direction of the magnetic disk surface in the DC erase area. The servo data is recorded by reversing with the magnetic disk. Disk servo information recording method.