JPH10106192A - Servo disk, magnetic disk device using it and manufacture of servo disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce track pitch fluctuation caused by that mutual positional fluctuation between a magnetic head and a disk medium at a servo information recording time due to an asynchronous runout of a disk drive part is printed into servo information. SOLUTION: In manufacture of a servo disk provided with a servo information recording process recording the follow controlling servo information of the magnetic head for the servo disk of a magnetic disk device provided with the servo disk drive part driving the servo disk and the magnetic head recording/reproducing the information on the servo disk, the servo information recording process is provided with a discontinuous recording process S3 alternately recording servo sector information when the servo disk turned by the servo disk drive part is rotated differently related to the adjacent sectors of the servo disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic disk drive, and more particularly to a sector servo type magnetic disk drive. Further, the present invention relates to a recording method for recording servo information on a servo disk of the magnetic disk device,
In particular, the present invention relates to a recording method that considers vibration of a disk drive during recording of servo information.

[0002]

2. Description of the Related Art Recent magnetic disk devices employ a sector servo system. In the magnetic disk drive of the sector servo system, a servo information area (servo sector) extending in a wedge shape in the radial direction is formed at a time interval of 30 to
There are 100. The position of the magnetic head is detected from the servo information of the servo sector read by the magnetic head, and the magnetic head follows the data track.

Therefore, servo information serving as a reference for position detection must be recorded on a disk medium with high accuracy. Servo track writer (STW) having a precise positioning mechanism using a high-precision position measuring device such as a laser interferometer in the manufacturing process
Written by equipment called. In this case, a mechanical mechanism called an HDA (head disk assembly) of the magnetic disk device is assembled in a state close to a completed product, and servo information is written on a disk medium using the magnetic head and the spindle motor of the magnetic disk device itself. Written.

[0004]

However, the spindle for recording the servo information does not use a special high-precision air bearing like a spin stand used for evaluation of a disk. Because the disk itself is 0.2-0.3u
Mpp is shaking. Therefore, no matter how the magnetic head is positioned with high accuracy, the position is a positional displacement with respect to a reference point on the servo writer, and does not follow the shaking of the disk. There was an inconvenience that data was written on the track that fluctuated by the amount of the shaking.

In recent magnetic disk devices, the recording density has been rapidly increased, and the track pitch has been reduced to about 3 μm, so that the relative position fluctuation between the magnetic magnetic head and the disk medium during servo track writing cannot be ignored. . Also, the track pitch has become so narrow that the positioning accuracy of the magnetic head positioning mechanism of the servo track writer cannot be said to be sufficient.

Even if the fluctuation at the time of recording the servo information is asynchronous with the rotation, once the information is written and the information is reproduced and demodulated as position information, the fluctuation of the writing position is imprinted as the fluctuation of the recording position. , The same position fluctuation is shown every rotation, and it appears as a run-out synchronized with the rotation. The asynchronous runout at the time of STW also exists when writing the position information of the adjacent track, and the trajectory of the recording position fluctuates differently between the adjacent tracks, so that the track pitch fluctuates and the space between the adjacent tracks is blocked. However, a read error is likely to occur.

[0007] What has been described above is the IEEE TRANS.
ACTIONS ON MAGNETICS, VOL.
32, NO. 3, MAY 1996 PP1799-1
804, Kok-Kia Chew's paper "CON
TROL SYSTEM CHALLENGES TO
HIGH TRACK DENSITY MAGNE
Chapter 4 1801 of "TIC DISK STORAGE"
Page 1802 also describes the case where an MR (magnetoresistive) head (more precisely, a combined MR head for reading and a thin-film head for writing) is used.

In this paper, when the magnetic center of the thin film head and the MR head are largely displaced from each other, the servo information written during different spindle rotation passes by the STW for writing (writing) and reading (reading) is used. This explains that this causes a position shift between the write and the read. Therefore, reducing the influence of asynchronous runout during STW is an important issue for increasing track density in the future.

As a prior art for improving track pitch fluctuation, Japanese Patent Application Laid-Open No. 60-136070 discloses a method of reading a servo signal on a servo track writer and rewriting the signal so as to reduce the fluctuation. This is mainly a countermeasure for disk media defects.
In the case of rewriting, the same degree of shaking exists during rewriting, so that the effect is small. Also, the writing time may be extremely increased.

Japanese Patent Application Laid-Open No. 8-55447 discloses a method of detecting a disk shake with a clock head of a servo track writer and changing a write position so as to cancel the shake. This seems to be effective if successfully implemented, but has the drawback of being technically difficult. Further, when the number of disks is large (for example, when five disks are used), there is a disadvantage that the amount of fluctuation detected by the clock head is different on the other disk surfaces, so that a cancellation error increases.

[0011]

An object of the present invention is to improve the disadvantages of the prior art, and in particular, the relative position fluctuation between the magnetic head and the disk medium caused by asynchronous vibration of the spindle motor during recording of servo information is imprinted on the servo information. It is an object of the present invention to provide a magnetic disk drive capable of reducing track pitch fluctuations caused by the above and a method of manufacturing the magnetic disk drive.

[0012]

Therefore, according to the present invention, when recording the servo sector information in a sector disk type magnetic disk drive, a plurality of servo sectors per circumference are continuously recorded between adjacent sectors. Instead, adjacent sectors are recorded during different rotations. When writing a conventional sector servo pattern with a servo track writer,
The pattern at one radial position on one surface was sequentially written in one revolution for all sectors. As a result, when the servo information was read and demodulated into a position signal, a runout (relative position fluctuation) asynchronous to the rotation between the magnetic head and the disk medium at the time of writing the servo pattern was reproduced as a synchronous runout in the position signal.

According to the present invention, when writing a servo pattern, one round of the servo pattern is not sequentially written in one rotation, and the adjacent sectors are written in different rotations. Aperiodic runouts with different rotations are reproduced while being sequentially switched. Asynchronous runout at the time of writing is divided for each sector, and is switched to discontinuous runout at the time of different rotation. Vibrations caused by the bearings are called rolling element passing vibrations, and mainly vibrations of about 300 to 800 Hz. Originally, the asynchronous run-out component of 300 Hz to 800 Hz is switched at a sampling frequency of 4 kHz to 20 kHz (the reciprocal of the sector period), and switches to discontinuous amounts.

Normally, since the control band of the track following operation is 1/10 or less of the sampling frequency, it cannot follow the run-out component which fluctuates at the sampling frequency or 1/2 to 1/3 thereof. Become.
As a result, the track following trajectory of the magnetic head has an average runout at the time of STW, and the effect of reducing the fluctuation of the track pitch is obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing an outline of the method for manufacturing a servo disk according to the present embodiment. As shown in FIG. 1, first, a method of manufacturing a servo disk is performed after assembling a magnetic head. FIG.
As shown in FIG. 1, first, a disk installation step of installing a disk unit having a servo disk recording servo information for positioning a magnetic head and a disk recording ordinary data on a disk drive unit for rotating the disk unit
1. A magnetic head installation step of arranging a magnetic head for recording and reproducing data facing each disk surface of the disk unit and installing the magnetic head on a magnetic head drive unit for moving the magnetic head to the inner and outer circumferences on the disk surface By S2,
Manufacture a magnetic disk assembly.

In the servo information recording step S3, the servo disk of the magnetic disk device having the servo disk drive unit assembled in steps S1 and S2 for driving the servo disk and the magnetic head for recording and reproducing information on the servo disk is recorded. On the other hand, servo information is recorded. The servo information recording step includes a discontinuous recording step of alternately recording servo sector information at different rotations of the servo disk rotated by the servo disk driving unit for adjacent sectors of the servo disk.

As described above, in the discontinuous recording step, the servo sector information is recorded in the adjacent sectors of the servo disk during different rotations, so that the runout due to the vibration of the disk drive unit is arranged non-uniformly and discontinuously. Therefore, the follow-up position of the magnetic head does not periodically shift.

This discontinuous recording step includes, for example, a first step of recording servo information in every other sector in the first rotation of the servo disk and a second step of recording servo information in the remaining sectors in the second rotation. 2 steps.

In the first step and the second step, servo information is recorded at different rotations in adjacent sectors, so that run-out positions are not continuous for adjacent sectors. Usually, the track following operation according to the servo information
Since it cannot follow the runout component, it follows the average of the runout. For this reason, if the run-out position is discontinuous for each sector, the average value becomes smaller, and therefore, the fluctuation of the track pitch becomes smaller.

FIG. 2 shows the configuration of a magnetic disk drive having a servo disk manufactured by the manufacturing method according to the present embodiment. The magnetic disk device includes a disk unit having a servo disk 3 recording servo information for positioning a magnetic head and a disk recording ordinary data, a disk drive unit (spindle) 2 for rotating the disk unit, and a disk unit. A magnetic head 4 for recording and reproducing data facing each disk surface, a magnetic head drive unit (actuator) 6 for moving the magnetic head 4 to the inner and outer circumferences on the disk surface, and a magnetic head for operating the actuator. A control unit (servo control circuit 24 and the like) for controlling based on servo information read from the servo disk by the head 4.

Further, the magnetic disk device has a magnetic head support mechanism (carriage) 5 for moving the magnetic head 4 to the inner and outer circumferences on the disk surface, and a spindle motor for rotating the spindle 2 (shown in FIG. 2). Without).

The control unit includes a spindle motor control circuit 20 for driving a spindle motor, a write control circuit 21 for writing information on a disk surface with a magnetic head, and a read channel circuit 22 for reading information with the magnetic head.
A position information detecting circuit 23 for separating and extracting servo information from the read channel circuit 22; and a servo control circuit 24 for controlling the actuator 6 using the position information to move and position the magnetic head 4 to a desired track. And an interface control unit 25 that controls a group of circuits and controls an interface with a higher-level device.

The magnetic disk drive has a standard configuration, and its operation is the same as that of the conventional one. The difference from the conventional magnetic disk device lies in how to write the servo pattern.

The servo disk 3 has a relative position change (runout) at the time of servo information recording due to the vibration of the disk drive unit (spindle) 2 discontinuously in adjacent sectors. The servo disks are arranged unevenly (randomly) in the reading direction. Such a run-out arrangement was recorded in the discontinuous recording step S3 shown in FIG.

Further, the control section has a follow-up control function for controlling the track following operation of the magnetic head with a width smaller than the fluctuation width of the relative position fluctuation of the servo disk. Usually, the control band of the track following operation is 1/1 of the sampling frequency.
Since it is 10 or less, it cannot follow the run-out component that fluctuates at the sampling frequency or 1/2 to 1/3 thereof, and follows the average thereof. That is, when following from one sector to the next sector, the width of the relative position change (runout) between the sectors (the length in the disk radial direction) is larger than the width which is the unit of the tracking control of the magnetic head. Therefore, it cannot follow the relative position fluctuation.

By repeating the track following based on the servo information without following the relative position fluctuation,
The track following trajectory of the magnetic head is obtained by averaging the runout at the time of recording the servo information. For this reason, according to the present embodiment, when the runout is discontinuous for each sector and the width is uneven, the effect of reducing the track pitch fluctuation is obtained.

As described above, in the magnetic disk drive according to the present embodiment, since the discontinuous runouts are randomly arranged, the magnetic head follows the average of the runouts, and therefore, the servo information recording due to the vibration of the disk drive unit. The effect of runout at the time can be reduced.

Next, a description will be given of a servo track recording apparatus which is an apparatus directly used for implementing the method of manufacturing a servo disk according to the present invention. FIG. 3 shows a servo track recording device (S
FIG. 2 is a block diagram of a TW (servo track writer). In FIG. 3, reference numeral 1 denotes an H to which a servo pattern is to be written.
DA (head disk assembly).

Spindle 2 on aluminum base of HDA1
Are fixed, and five disks 3 are mounted on the spindle. The spindle 2 is rotated at 7,200 rpm by a spindle motor (not shown). The control circuit 20 of the spindle motor is not shown in FIG. There is one magnetic head 4 for each disk surface,
A total of ten magnetic heads are supported by the carriage 5. The carriage 5 is driven by an actuator 6 and can rotate about 30 degrees around the pivot. The actuator 6 is of a type called a VCM (voice coil motor) and includes a fixed magnet and a movable coil.

The HDA 1 is fixed on an anti-vibration table of a servo track recording apparatus when writing a servo pattern. In order to detect the position of the magnetic head 4, the carriage 5
A mirror 7 for a laser length measuring instrument is mounted on the arm of. Although the cover is omitted in FIG. 3 to show the inside of the HDA, in reality, the cover is attached to the HDA, and the mirror 7 is connected to the arm through the slit of the cover, and the mirror section is formed of the HDA. Outside.

A clock head 8 is inserted through a hole in the HDA cover to generate a reference clock signal for writing a servo pattern. The laser length measuring device 9 includes a laser light source 10
The change in the distance between the interferometer 11 and the mirror 7 is detected using the laser light from The head position control circuit 12 controls the actuator 6 based on the position information.
The clock head 8 has a clock write / read circuit 13
Are connected, and there is a timing generation circuit 14 at the end.

The timing generation circuit writes clock information with the clock head 8 so that the clock has a predetermined number per rotation in order to generate a reference clock signal before writing the servo pattern. At this time, a pattern indicating the starting point of one round is also embedded in the clock information. When writing the servo pattern, the timing generation circuit 14 generates a clock signal and an index signal indicating the starting point of one round of the disk based on the clock signal obtained from the clock head 8.

A servo pattern writing circuit 15 writes a servo pattern based on the information of the timing generation circuit 14 and the position information of the head position control circuit. The present invention is characterized in that the writing order in units of servo sectors when the servo pattern writing circuit 15 writes the servo pattern is different from the conventional order. The fine writing sequence corresponding to the configuration in one servo sector is the same as the conventional one.

In this embodiment, there are 64 sectors per round. FIG. 4 shows the arrangement of the servo sectors. Writing with a total of 64 rotations, one sector per rotation, is considered the best in reducing the effect of asynchronous runout during servo track recording, but it takes too much time. Write a servo sector and write one round in two revolutions.

When there are ten magnetic heads, writing one by one takes ten times as long as one magnetic head.
When writing a servo pattern, use R / WLSI (eg, SS
I company's 32R1561R) bank write function for 5
Since it is possible to write one by one at the same time, in a normal servo pattern writing method, five lines (bank 0) are written in the first rotation, and the remaining five lines (bank 1) are written in the second rotation. This control is shown in the time chart of FIG. 5 as a bank switching signal by a conventional writing method in comparison with the control of the present invention.

In this embodiment, in FIG. 4, when sector 0 is written with the magnetic head of bank 0, the next sector 1 is written with the magnetic head of bank 1, and the next sector 2 is written with the magnetic head of bank 0 again. Write alternately. Conversely, in the second rotation, sector 0 is written with the magnetic head of bank 1, and the next sector 1 is written with the magnetic head of bank 0. In this manner, a servo pattern to be written at the radial position can be written in all the servo sector positions in one round for all ten magnetic heads in two rotations.

In this case, the writing time is not different from the conventional one. This control sequence is shown in FIG. However, the (-) write gate signal may actually be opened and closed finely to write a desired pattern in one servo sector. Here, such fine control is related to the core of the present invention. Since there is no write operation, only the write operation is performed at the L level at the position of the servo sector.

Since the run-out amount imprinted for each sector changes discontinuously for each sector, the run-out amount is averaged in the track following operation, and the track pitch fluctuation can be reduced. FIG. 6 is a diagram showing the effect. NR of the first rotation
RO (non-repeatable run-out) and NR at 2nd rotation
Since RO is a non-periodic run-out, it differs as shown in FIG.

In the present embodiment, the sectors written under the NRRO in the first rotation and the sectors written under the NRRO in the second rotation are alternately arranged. Indicates a discontinuous step change.
Since the track following characteristic cannot follow a step change, the track following characteristic is close to the average, and the runout is reduced.

In order to further enhance the effect of the present invention, instead of directly using the servo information written by the writing method described in the above-described embodiment as position information, estimation was made by a state estimator for estimating position, speed and external force. The position may be used for a track following operation. State estimators are a major achievement of modern control theory and are also called observers or estimators. A digital model of the control target is created, the position, speed, and external force are simulated in real time, the measured position information is compared with the estimated position, and the error between them is fed back to the simulation. Since the filter effect of the state estimator also works, runout averaging can be realized more smoothly.

Next, a second embodiment will be described. In the above embodiment, the whole is completed in two rotations, so the NRR of two rotations is obtained.
It follows the average of O. In this case, if there are many random components in the NRRO component, the averaged result tends to be flat, but if the specific frequency component is large, for example, 3
When the 80 Hz component is dominant, 1 at 7200 rpm
After rotation, ie, after t = 1/120 = 8.33 ms, 3
80 Hz is sin (2π × 380/120) = sin
Since it is (π / 3), the phase is shifted only by 60 degrees, and even if it is averaged, √3 / 2 = 0.87, that is, only -13% is reduced.

If it is limited to 7200 rpm and 380 Hz, the phase is shifted by 60 degrees in one rotation. Therefore, if writing is performed every other writing and then the rest is written in the third rotation, the phase is shifted by 180 degrees. Since the position information obtained is alternately opposite in phase, the position information is well canceled out, and the effect of reducing track pitch fluctuation can be increased.

Considering the general case where a random component and a specific frequency component are mixed, it is more random to write one servo sector in three or four rotations instead of two rotations (non-uniformity). It is considered that the trajectory of the magnetic head tends to be flat.

Therefore, the second embodiment is an example in which one round is written by a plurality of rotations of three or more. In the second embodiment, a dividing step of dividing the sector into a plurality of groups (for example, three groups) in which adjacent sectors of the servo disk are arranged in a discontinuous order, and a group in which servo information is sequentially written for each group And a separate recording step.

When writing in three rotations, sectors 0, 3, 6, 9, and-are written in the first rotation, and sectors 1, 4, 7, 10, and-are written in the second rotation in three rotations. Sector 2 by eye
One way is to write 5, 8, 11, ----. However, in this case, when the number of rotations to be written in the sector order is displayed, 1,2,3,1,2,3,1,2,2
3, ---- and the periodicity may easily occur. Therefore, in this example, the order of the number of rotations to write is (1,
2,3), (1,3,2), (3,1,2), (3,
(2,1), (2,3,1), (2,1,3), (repeated heretofore) and so on.

Next, a description will be given of an example in which all the sectors in one rotation are written in four revolutions. In this example, the division step includes a rearrangement step of rearranging the sectors in each group in such an order that part or all of the order of the sectors is in a different position for each group. The rotation cycle for writing in sector order is 1, 2, 3,
Although it may be simply repeated as in 4, 2, 2, 3, 4, ---, here, when a set is made in units of 4 in the order of the sector number in the same way as in the second embodiment. ,
The reordering process changes the order such that there are no sectors to be written in the same rotation cycle, and that the adjacent set of adjacent sectors is not written in the same rotation cycle. In this example, the number of rotations to write in the sector order is (1, 2, 3, 4), (1, 2, 4, 3), (1, 2).
3, 2, 4), (1, 4, 2, 3), ---.

FIG. 6 shows the number of rotations for writing 64 sectors in the second and third embodiments.

As described above, according to each embodiment,
As the asynchronous runout of multiple rotations recorded at the time of writing the servo pattern switches discontinuously, the track following servo cannot sufficiently follow the stepwise change and the position of the magnetic head follows the average of them. become. As a result, the fluctuation range of the synchronous runout becomes smaller, and the track pitch fluctuation between adjacent tracks becomes smaller. In addition, the accuracy of the spindle motor and the servo track writer may be the same as the conventional one, and can be easily realized because only the writing order is devised. Thus, the first effect is that interference between tracks is reduced and the read margin is improved.
The second effect is that the track density can be further improved.

[0049]

Since the present invention is constructed and functions as described above, according to the first aspect of the present invention, there is provided a method for recording servo information at the time of recording servo information which occurs in response to the vibration of a disk drive for rotating a servo disk. Since the relative position fluctuation is discontinuous for the adjacent sector, the relative position fluctuation rarely becomes an element of the periodic displacement, and furthermore, the discontinuous relative position fluctuation is caused in the reading direction of the servo disk. Since the magnetic heads are tracked and controlled by this servo information, the magnetic heads are tracked at the average position of the relative position fluctuation occurring in a non-uniform order,
Therefore, it is possible to reduce the influence of the position fluctuation caused by the vibration of the disk drive unit. As described above, it is possible to provide an unprecedented excellent servo disk in which the follow-up position of the magnetic head does not periodically shift.

Further, in the invention according to claim 2, the control section controls the track following operation of the magnetic head with a width smaller than the fluctuation width of the relative position fluctuation of the servo disk.
When following from the sector to the next sector, the width of the relative position change (runout) between the sectors (the length in the disk radial direction) becomes larger than the width which is the unit of the tracking control of the magnetic head. Therefore, the magnetic head cannot follow the relative position change, and repeats the track following based on the servo information without being able to follow the relative position change. Since the average is obtained and the runout is discontinuous for each sector and the width is uneven, the fluctuation of the track pitch can be greatly reduced as compared with the conventional case. Therefore, it is possible to remove an unstable element at a follow-up position due to vibration of the disk drive unit, and therefore, to obtain a higher-density and superior magnetic data than ever before. It is possible to provide a disk device.

According to the third aspect of the present invention, in the discontinuous recording step, the servo sector information is recorded alternately at adjacent rotations of the servo disk at different rotations of the servo disk rotated by the servo disk drive section. Provided is an unprecedented superior manufacturing method capable of manufacturing a servo disk having discontinuous relative position fluctuations in adjacent sectors during recording of servo information caused by vibration of a disk drive unit that rotates the disk. Can be.

As described above, according to the present invention, asynchronous relative position fluctuation (run-out) due to vibration of the disk drive unit.
The relative position fluctuation between the magnetic head and the disk medium at the time of recording the servo information due to the above is imprinted on the servo information, and the resulting fluctuation of the track pitch can be effectively reduced. And a method of manufacturing the servo disk.

[Brief description of the drawings]

FIG. 1 is a schematic flowchart showing a method for manufacturing a servo disk according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of the magnetic disk drive according to the present embodiment.

FIG. 3 is an explanatory diagram showing a configuration of the servo track recording device according to the present embodiment.

FIG. 4 is a diagram showing an example in which servo tracks are recorded on the magnetic disk device shown in FIG. 2 by the manufacturing method shown in FIG. 1 by the servo track recording device shown in FIG. 3; 4) shows an example of the arrangement of sectors.
(B) is a diagram showing an example of a servo burst.

FIG. 5 is a time chart showing recording timing of servo information according to the manufacturing method shown in FIG. 1;

6 is an explanatory diagram showing an example of a track following position of a magnetic head of the magnetic disk device shown in FIG. 2 manufactured by the manufacturing method shown in FIG. 1;

FIG. 7 is an explanatory diagram showing a correspondence relationship between a servo sector and a write rotation cycle in the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 HDA 2 spindle (disk drive unit) 3 disk (servo disk) 4 magnetic head 5 carriage 6 actuator (magnetic head drive unit) 7 mirror 8 clock head 9 laser length measuring device 10 laser light source 11 interferometer 12 head position control circuit 13 Clock Write / Read Circuit 14 Timing Generation Circuit 15 Servo Pattern Write Circuit 20 Spindle Motor Control Circuit 21 Write Control Circuit 22 Read Channel Circuit 23 Position Information Detection Circuit 24 Servo Control Circuit 25 Interface Control Unit

Claims (6)

[Claims] 1. A servo disk in which servo information used for tracking control of a magnetic head is recorded for each sector, wherein the sector is generated in response to a vibration of a disk drive for rotating the servo disk with respect to the adjacent sector. A servo disk having discontinuous relative position fluctuations at the time of recording servo information, wherein the discontinuous relative position fluctuations are non-uniformly arranged in a reading direction of the servo disk. 2. The servo disk according to claim 1, a disk drive for rotating the servo disk, a magnetic head for recording and reproducing data facing the disk surface of the servo disk, and the magnetic head A magnetic head driving unit that moves the magnetic head to the inner and outer circumferences on the disk surface, and a control unit that controls the operation of the magnetic head driving unit based on servo information read from the servo disk by the magnetic head. The magnetic disk device according to claim 1, wherein the control unit has a following control function of controlling a track following operation of the magnetic head with a width smaller than a fluctuation width of a relative position fluctuation of the servo disk. 3. A servo disk for a servo disk of a magnetic disk device having a servo disk drive unit for driving a servo disk and a magnetic head for recording and reproducing information on and from the servo disk. In a method for manufacturing a servo disk having a servo information recording step of recording, the servo information recording step is such that the servo sectors are rotated at different rotations of the servo disk by the servo disk driving unit for adjacent sectors of the servo disk. A method for manufacturing a servo disk, comprising a discontinuous recording step of alternately recording information. 4. The discontinuous recording step includes a first step of recording servo information in every other sector in the first rotation of the servo disk and a second step of recording servo information in the remaining sectors in the second rotation. 4. The method for manufacturing a servo disk according to claim 3, comprising the following two steps. 5. The discontinuous recording step includes a dividing step of dividing the sectors into a plurality of groups in which adjacent sectors of the servo disk are arranged in a discontinuous order, and a group-specific recording in which servo information is sequentially written for each group. 4. The method according to claim 3, further comprising the steps of: 6. The method according to claim 1, wherein the dividing step includes a rearranging step of rearranging the sectors in each group so that a part or all of the order of the sectors is in a different position for each group. 6. A method for manufacturing a magnetic disk drive according to claim 5.