JPS6344383A - Control method for positioning head - Google Patents

Abstract

PURPOSE:To immune from the time-out of a controller by positioning a recording track in a fine track position based on read-out servo information and returning said track to a read action from a final gap position. CONSTITUTION:A servo track writing the servo information is formed on a magnetic disk 1 previously, independent of the recording track, and a magnetic head 2 is caused to seek a servo track from the recording track in a final gap where no data is written. Thus a controller 22 makes no judgement of errors, and the recording head 2 can be isolated from the recording track. The servo track can obtain servo information. Then the head 2 is returned to its original recording track from the servo t rack, and positioned in the fine track position of the recording track based on the servo information. Afterwards, when the head 2 is positioned in the final gap, it is again returned to a read state before the seek session.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the positioning of a head device with respect to a recording track in an information recording medium drive device that drives an information recording medium to record/reproduce information.

[Conventional technology]

Various types of disk drives are known for recording and/or reproducing information by rotationally driving an information recording medium, for example, a disk-shaped magnetic recording medium (hereinafter referred to as a magnetic disk). However, especially for small-sized devices that require a large amount of information, disk drive devices, also called hard disk devices, are often used. This hard disk drive rotates a magnetic disk, which has a magnetic recording layer formed on the surface of a hard disk, at high speed, and makes a magnetic head levitate above the surface of the magnetic disk to perform recording/reproduction.

An example of this type of disk drive device is shown in FIG. In the figure, the disk drive device includes a magnetic disk 1 for recording memories, a magnetic head 2 for recording/reproducing information on the magnetic disk 1, and a direct drive motor (not shown) for rotationally driving the magnetic disk 1. (Hereinafter, D
A head drive mechanism 4 for moving the magnetic head 2 to a predetermined track on the magnetic disk 1; A base plate 5 serving as a base,
It mainly consists of a printed circuit board 6 on which a motor drive circuit, a control circuit, etc. are formed, and a frame (not shown) for attaching this printed circuit board 6 to the base plate 5.

In this magnetic disk device, the magnetic disk l is
Two magnetic heads 2 are provided, and since double-sided recording is performed on one magnetic disk 1, one magnetic head 2 is provided on each surface, a total of four magnetic heads 2 are provided. It is attached via a support spring. The head drive mechanism 4 consists of this swing arm 8, a steel belt 9 attached to a part of the swing arm 8, a pulley 10 around which the middle part of the steel belt 9 is wound, and a stepping motor 11. By inserting and fixing the pulley 10 around which the steel belt 9 is wound onto the drive shaft 12 of the stepping motor 11, and moving the stepping motor 11, the swing arm 8 is rotated about the rotating shaft 8a. It can be swung as follows.

The housing that houses the magnetic disk 1, magnetic head 2, swing arm 8, steel belt 9, pulley 10, etc.
Consisting of the base plate 5 and a top cover (not shown), gaskets are used at the contact area between the base plate 5 and the top cover and at the mounting area of the stepping motor 11 to maintain airtightness, and magnetic fluid is used at the shaft of the DD motor. is filled. Further, a shutter 17 is provided on the antimagnetic head mounting side 8b of the swing arm 8 so as to protrude outward. Furthermore, the airtight chamber 5a of the base plate 5
On the side, there is a photointerrupter 1 as an outside sensor.
8, and is arranged so that the shutter 17 can be loosely inserted into the insertion path 18a of the photointerrupter 18. In this conventional example, when the magnetic head 2 reaches the zero track position on the outer periphery, the shutter 17 blocks the optical path formed in the insertion path 18a of the photointerrupter 18.

By the way, when moving the magnetic head 2 using the stepping motor 11 as described above, it becomes difficult to position the head as density increases. In other words, in hard disk drives, since the expansion coefficients of the materials inside the drive differ, there is a problem called thermal off-track where the position of the magnetic head 2 relative to the track shifts due to temperature changes. In a hard disk drive, it is generally difficult to position the magnetic head 2 without using a servo when the TPI exceeds 400 TPI.

One of the control methods using this servo is JP-A-57-86.
There is an invention disclosed in No. 910. This invention uses one data-masked servo sector containing track centerline servo control data that can be successively output by the head to position the head from servo information once per revolution of the magnetic disk. ing. therefore,
In this type of servo control method, the data recording area becomes shorter by the amount of servo information, so the rotation speed is slightly lowered to adjust the transfer speed. Therefore, there is a possibility that the head may become slightly unstable.

Another control method using servos is to use the innermost and outermost tracks as dedicated servo tracks. This method uses the inner diameter (In5i-de Dia
meter ), outside diameter
This is an abbreviation of ID-OD method.

In this method, the disk device first reads the outer servo track and adjusts the mL% so that the head is centered on the track. The head is then moved toward the inner servo track. At this time, the number of step pulses of the stepping motor of the head drive mechanism is counted, and when the head reaches the inner servo track,
The head positioning mechanism performs precise positioning so that the head is centered on the track. Then, during precise positioning of each servo track, the positioning mechanism learns the amount of correction needed to find the center of the track. Once this amount of correction is known, the positioning mechanism can calibrate the exact position of each track with information about the number of step pulses required to move between the outer and inner tracks and the amount of microstep correction required on each servo track. It is now possible to do so.

However, with this method, the positioning mechanism has to repeat the calibration procedure every time a positioning error occurs, so if this happens frequently, a lot of time is wasted that is not directly related to recording/playback. , the utilization efficiency of the disk drive decreases. Also, once the head is on the data track, there is no guarantee that the head will be held in the correct position since there is no means for readjustment.

For these reasons, the applicant has realized that there is no need to reduce the rotation speed, and the head can be positioned at an accurate track position (fine track position) by reading servo information at any time, resulting in an efficient system with less wasted time. Patent application 1986-14 for a head positioning control method that can provide a disk drive device
It was proposed as No. 0351.

The proposed invention relates to a recording medium drive device that writes or reads signals to or from a recording track on an information recording medium via a head device, and in a method for positioning the head device with respect to the recording track. It is structured as follows.

First, if a stepping motor is used as a head transport motor for an information recording medium, a preset number, for example, 1 One (pair) or several (pairs) of servo information are assigned in correspondence with an internal index signal to form a servo track. At the time of writing or reading, the head device is moved from the recording track to which servo information is to be written to the servo track to which servo information has been added at any time, and the servo information is read out. The head device is positioned at a fine track position with respect to the servo track by controlling the drive voltage supplied to the servo track, and then the head device is returned to the recording track before movement, and the head device is positioned to the fine track position with respect to the servo track based on the positioning information. , the head device is positioned at the fine track position of the target recording track. As a result, when writing and reading,
It is intended that fine track within a desired range can be achieved.

On the other hand, as an interface with a controller of a disk drive device, an interface called 5T-506 compatible is often used for magnetic disks adopting a floppy-like format. In the floppy-like format, there is one index per rotation of one track, and data is handled by dividing the area from index to index into many sectors. The format is such that a gap is provided between the last sector and the index, and a gap for absorbing rotational fluctuations that is longer than other gaps is provided between the last sector and the index.

[Problem that the invention seeks to solve]

By the way, the 5T-506 interface does not have a means to inform the disk drive side whether or not the controller is reading the data signal output from the disk drive device. Therefore, while reading, the disk drive
If the J device transfers the magnetic head to the servo track side and performs predetermined positioning control, an error may occur on the controller side. In other words, when reading from one track to another,
When seeking from one track to another, it goes to the servo track to calibrate the position, and when moving to another track, it issues a seek complete signal indicating that the seek operation is finished, and receives the seek complete signal. After that, the read operation is performed, so even if the instruction is from the disk drive side, the controller will not judge it as an error. However, when one track is being read continuously, when the disk drive issues a servo command and causes the head to seek to the servo track, the controller should send the read data. Since it is no longer sent, there is a very high possibility that it will be determined as an error.

This invention was made in view of the above technical background, and its purpose is to enable servo control in response to servo commands from a disk drive even when using the 5T-506 interface. The object of the present invention is to propose a head positioning control method using a servo track in which servo control is not disabled due to a controller determining an error.

[Means for solving problems]

In order to achieve the above object, the present invention provides a recording medium drive device that writes or reads a signal to or from a recording track on an information recording medium via a head device.
In a method of positioning the head device with respect to a recording track, when a servo track on which servo information is written is formed only at a preset track position of an information recording medium, and read operations are performed continuously on one track. To do this, move the head device from the recording track to the servo track at the final gap position following the final sector, read the servo information from the servo track, and then return the head device to the previous recording track and read the servo information that was read out. Based on this, the fine track position with respect to the recording track is determined, and then the reading operation before the movement is resumed from the final gap position.

[Effect]

The above means works as follows.

That is, a servo track on which servo information is written is previously formed on the recording medium separately from the recording track, and the head device is caused to seek from the recording track to the servo track in the final gap where no data is written. This allows the controller to deviate from the recording track without being judged as an error. Then, servo information is obtained from the servo track. Next, the head device is returned from the servo track to the original recording track, and the head device is positioned at a fine track position of the recording track based on the servo information.

Then, when the head device is located at the final gap (
(for example, using an internal index to detect), again,
Return to the read state before seek. During this time, even if valid read data is not sent, the controller side is not in a control state to read normal read data, so it will not be determined as an error. Also, when normal read data is restored, normal steps are taken after passing through the external index and the first gap, so that no error is determined in this case either. Furthermore, while seeking to this servo track, in order to prevent problems with the followability of the data separator and errors due to incorrect data reading by the controller, send dummy data and do not send index pulses to the controller. By making the seek complete signal inactive, controller timeout (error checking when there is no data within a certain period of time) can be avoided.

〔Example〕

Hereinafter, an example of implementation of the present invention will be described based on the drawings.

Figures 1 to 6 are for explaining the present invention in detail. Figure 1 is a flowchart showing the procedures for seek and head position calibration using the final gap, and Figure 2 is an explanatory diagram of the track format. , FIG. 3 is a block diagram showing the control system of the disk drive device according to the embodiment, FIG. 4 is an explanatory diagram showing the recording track of the magnetic disk and the writing state of the servo signal, and FIG. 5 shows the area of the magnetic disk. The explanatory diagram, FIG. 6, is a block diagram showing an example of a servo circuit.

Further, the disk drive device itself is the same as the conventional example shown in FIG. 7, and in the following explanation, the same reference numerals are given to components that are the same or can be considered to be the same as those of the conventional example.

In FIG. 3, the control system of the disk drive device controls the DD motor 3 that rotates the magnetic disk 1 and the stepping motor 11 that swings the swing arm 8, and sends and receives signals to and from the head amplifier 21. The drive circuit 22 is interfaced with a servo circuit 23 that processes the servo information read by the magnetic head 2 and amplified by the head amplifier 21 and sends an electric signal related to servo control to the drive circuit 22. 2
It is mainly composed of a controller 25 which is controlled via a controller 4. The controller 25 and host computer 26 are connected by a bus 27, and the magnetic head 2
It is possible to process signals detected by the magnetic head 2 or signals sent to the magnetic head 2.

FIG. 5 shows servo tracks formed on the magnetic disk 1,
This shows an example of a recording track to which servo information is not attached.

The magnetic disk I is, for example, a thin aluminum plate coated with a magnetic coating, and has an inhibit zone I formed at its innermost circumference where no data is written, and a data zone D formed at its outer circumference. In the data zone D, 600 recording tracks T are formed concentrically, and the data zone D is divided into approximately three parts, each of which has a group of four tracks as shown in FIG. A group of servo tracks is formed. The servo track groups are an outer servo track group O3T, an intermediate servo track group MST, and an inner servo track group IST, and each servo track group O3T, MST
, IST has servo zone 03Z in which servo signal F is written as servo information with the servo signal F in the open position of about 180 degrees.
I.

O3Zz, MS Z+, MS Zz, I S Z+,
I S Zz is formed.

FIG. 4 is an explanatory diagram of a servo track group MST formed, for example, in the middle part, and the servo track group MST has four
Book servo track MST+, MSTz,
MST! , MST4. And each servo track MST, MST
z, MST:1. In MST4, servo signals F are applied in a staggered manner at the same frequency at positions equidistant with respect to the center line C in the longitudinal (circumferential) direction, corresponding to the first and second internal index signals IN, INz. are written alternately. And this is the above servo zone M
SZ+.

It corresponds to MSZz. In this case, since the servo signal F is written with the same magnetic head 2, the track widths of the servo signal F, the recording track T, and the servo tracks MST, ~MST are different from the length of the gear G of the magnetic head 2.
Off-track occurs when the position of the gap G of the magnetic head 2 deviates from the target recording track T.

In this example, servo zones OSZ, and 03Z2
, MSZ, and MSZ, , ISZ, and l5Z2 are 18
The phase difference of 0 degrees is formed in consideration of the convergence time for correcting the position of the magnetic head 2 and the rotation time per rotation of the magnetic disk 1. In other words, the time required for one rotation of the magnetic disk 1 is 3600
The rpm is approximately 16.67 msec, and the convergence time after driving the stepping motor 11 is approximately 3 msec.
36 (is.

Therefore, if the servo zones are out of phase by 180 degrees, for example, the servo signals F of the servo zones OS Z, MS Z, ISZ, corresponding to the first internal index signal Nl are read out and their positions corrected. Immediately after the correction operation converges, the servo zone 08Zz, M S Zz, r corresponding to the second internal index signal INz
By reading the SZZ no servo signal F, it can be detected whether the corrective action is appropriate.

In this case, since the rotation time per revolution of the magnetic disk 1 and the convergence time of the stepping motor 11 are in the above relationship, the phases of the servo zones are shifted by 180 degrees, so that two servo zones per rotation are However, it goes without saying that various selections can be made depending on the convergence time of the positioning operation of the stepping motor 11 or other types of drive motors, the rotational speed of the recording medium, etc. However, even if the motor type is different, it is thought that providing one or several servo zones per revolution will function satisfactorily.

Also, four servo tracks form a group.
This takes into consideration errors in the formation interval of the magnetic pole teeth of the stepping motor 11 and errors in the magnetization interval of the rotor. In other words, when using a 4-phase unipolar type or 2-phase bipolar type stepping motor, 4 steps with 1 phase excitation,
One cycle consists of 4 steps in 2-phase excitation, 8 steps in total.

At this time, it is known that the rotation angle error due to the excitation phase shows the same pattern every 1/2 cycle. Therefore, 1
If the rotation angle and excitation voltage can be corrected only for the four tracks corresponding to /2 period, when the same excitation phase and the excitation phase shifted by l/2 period are excited, The control conditions are the same for every other recording track T.

FIG. 2 shows an example of a typical format, and the area from gap IG to gap 4G is divided into 32 sectors corresponding to the external index signal EIN shown in FIG.

The gap IG is provided to absorb the deviation of the external index signal EIN, and has a length of 16 bytes, for example, in which IT 4 E N is written. Gear Tsubu IG+
The synter field (VFO5-ync field) SF that follows precedes the address search and is the VF of the controller.
Used to lock O(PLO). The data is only ALL"O", that is, the clock. To Syntafield! <ID field The address mark, cylinder, head, sector, and check code for this area are written in the ID field. The gap 2Gz following the ID field ID is called a write space gap, and is used to switch from the read state to the write state when writing to the data field DF, and to provide the switching time. The sink field SFz following the gap 20z is the ID
It has the same function as the sync field SF at the beginning of the field ID, but is rewritten by the write clock at the same time as the next data field DF. Then, data is written in the data field DF that follows. Following data field DF is gap 3G
's is provided. Gap 3G3 is an inter-record gap (Inter-RecordGa
Also referred to as p), there is a rotational fluctuation of the DD motor 3 while writing to the previous sector S.
Since there is a possibility that the next sector S may be destroyed, a predetermined length is formed. Then, from the sink field SF at the beginning of the ID field ID, this gap 3G'l
For example, 32 sectors are provided, with the up to 1 sector S being one sector S. A gap 4G as the final gap is provided following the 32nd sector gear 3G from the gap IG, and a predetermined signal such as IT 4 is provided until the external index signal EIN is detected.
E IF is written. This gap 4Ga is
It deals with speed fluctuations of the DD motor 3, and is also called a speed tolerance gap.

This gap 4G4 is 352 bytes in the traditional 256 bytes x 32 sector format, which corresponds to about 4.1% of the total number of bytes. In reality, it fluctuates due to speed fluctuations of the DD motor 3, and a predetermined region closer to the gap IG+ side is used for seek in servo control.

Further, the external index signal EIN corresponding to the gap I G + is obtained by detecting the rotational position of the pulse generating magnet 40 attached to the rotor of the DD motor 3 by magnetic detection means such as a Hall element, and detecting this by the first The internal index signal IN is set at the position where a predetermined count number is detected from the detection of the first internal index signal IN+. That is, when the count number is detected from the detection of the internal index signal IN, an external 1' index signal EIN is transmitted to the host computer 26 side, and this position becomes the beginning of the recording track T.

Next, the operation of the disk drive device configured as described above will be explained.

This type of disk drive has a relatively large temperature difference between when it is not in use and when it is in use. Therefore, immediately after the power of the disk drive device is turned on, the magnetic head 2 first scans one surface of the magnetic disk once, and the drive circuit 22 calculates the electrical quantity related to the excitation phase of the stepping motor 11 corresponding to each recording track T. A RAM table is created by storing the information in the RAM.

A positioning correction method that takes temperature rise into account is stored in advance in the microcomputer, and recording/reproduction is normally performed according to the servo algorithm stored in this microcomputer. That is, when a predetermined excitation phase is excited according to the above RAM table and recording/reproduction is performed on a desired recording track T, a servo command is sent from the microcomputer to the drive circuit 22 according to the above preset servo algorithm. When the command is issued, the magnetic helad 2 is moved to the servo zone MST closest to the currently located recording track T1 (or Ts), which corresponds to the same excitation phase as the recording track T1 (T,). track, e.g. M in FIG.
ST.

In this case, of course the recording track is T! (T6) position, the servo track will move it to the M S T K position.
If the Tx (Ty) position is the M S T z position,
If they are at the T4 (T11) position, they will be located at the MST4 position.

Now, when the same excitation phase is excited with the same voltage value, if the gap G of the magnetic head 2 is at the position A in Figure 4 and the servo signal F is read, then the servo signal level read first and the servo signal level read later are There will be a difference in the read servo signal level. Therefore, a servo circuit 2 as shown in FIG.
The signal is discriminated by the sample/hold circuits 28 and 29 of No. 3, and the signal levels are compared by the comparison circuit 30.

Then, the servo amplifier 3I sets a voltage value to be applied to the excitation phase of the stepping motor 11 according to the comparison value, and the stepping motor 11 is controlled via the drive circuit 22. As a result, the gap G of the magnetic head 2 moves to a symmetrical position with respect to the center line O and converges as shown as position B in FIG. 4, thereby defining a fine track position with respect to the servo track MST.

In this case, the RAM table may be updated based on the voltage value set by the servo amplifier, and the fine track position for the recording track T may be defined based on this RAM table.

Immediately after the movement of the magnetic head 2 converges, for the above-mentioned reason, the servo signal F of the second servo zone MSZ is read out, and it is determined from this second servo zone MSZ whether or not the above movement is appropriate. do. That is, if the output from the comparison circuit 30 in the second servo zone MSZt is below a preset level, the moving state is maintained as it is, and if it is above the preset level, the stepping motor 11 is driven again. Similar position control is performed to position the magnetic head 2 at a proper track position, that is, a fine track position.

The voltage value applied to the excitation phase of the stepping motor 11 when located at the fine track position is stored in the RAM of the drive circuit 22, and the magnetic head 2 is
While checking the table, return to the original recording track T3 position, and use the voltage value stored in the RAM to
A gap G position is defined for . As a result, a fine track is realized also for the recording track TI.

The RAM table is updated as needed in response to temperature rises or over time, so that the magnetic head 2 is always controlled based on the latest position data. In addition to correcting the head position according to the servo algorithm during recording/playback, the controller 2
5 or the host computer 26, the head position is determined in the same manner as above.

Further, when the magnetic head 2 continues to trace only on one recording track T, a servo command is issued from the drive circuit 22 according to the flowchart of FIG. That is, when a preset time has elapsed, it is determined in a first step 51 whether or not the servo calibration time has come. Then, when it is determined that the servo calibration time has come, the second
In step 52, it is determined whether the first internal index IN, which is provided at a position corresponding to the gap 4G and serves as a reference for writing the servo information IF, has been detected.

If the first internal index IN is detected in the second step 52, the process moves to the next third step 53. In this third step 53, a write gate (Write
Determine the level of Gate>.

When the write gate is at the If L IF level, the write gate is in an ON state, that is, the disk drive device is in a write state, and a write current flows. When it is OFF, it is always in a continuous read state, and if that disk drive is selected, read data is being output.

Therefore, in this third step 53, the write gate is
When it is not at the vL tv level, in other words when reading is being performed, there is no possibility that the controller side is determining that there is an error, so the next fourth step 54 is performed.
Proceed to. In this step 54, the read data is made dummy, and the magnetic head 2 is moved to the nearest servo track MS corresponding to the same excitation phase of the servo track group MST.
Make T l seek. And the fifth step 55
Then, the same servo control as described above is performed on the servo track MST, and the magnetic head 2 is positioned at a fine track position with respect to the servo track MST.

When the positional calibration of the magnetic head 2 with respect to the servo track MSTI is completed in this fifth step 55, the process moves to the next sixth step 56. The sixth step 56 is a step for obtaining an opportunity to return to the original recording track T and restart reading. When the fifth step 55 is completed, the original recording is resumed based on the position calibration data on the servo track. It seeks to the fine track position of track T1 and waits for the detection of the first internal index IN.

When the first internal index INI is detected, the read data is returned from dummy data to data from the normal recording track T1, and after a predetermined delay time from the detection of the first internal index INI, the external index EIN is returned. Output to the controller 25 side. This is,
After the magnetic head 2 returns to the recording track TI, a seventh step 57 is where normal recording/reproducing operations are performed.

Then, through this seventh step 57, the gap 4G
The head position calibration operation of the magnetic head 2 using , is completed.

As described above, according to this embodiment, for example, 5T-50
Even when using an interface such as a 6-interface that does not have a means to notify the disk drive side whether or not the controller is reading read data output from the disk drive, the drive circuit of the disk drive, controller or host Commands from the computer make it possible to seek to a servo track in any case and calibrate the head position by servo control.

In the above embodiment, in the fourth step 54, the read data is made dummy and the external index EIN is not outputted, but instead of not outputting the external index EIN, the seek complete signal is made inactive. The same operation as above can also be performed.

〔Effect of the invention〕

As is clear from the foregoing description, this invention enables the return of read data from the recording track to the servo track and from the servo track to the recording track in the final gap between the final sector and the first gap. According to: ■ Since the seek operation is performed in the final gap where no read data is written, the controller side will not judge it as an error even if it does not receive the read data, and it will not be judged as an error even when tracing the same recording track. This makes it possible to calibrate the head position based on commands from the disk drive, even when the head is on the disk. This allows the head position to be controlled using the servo track without worrying about errors in any case. It also allows the use of commonly used interfaces such as the 5T-506, which allows disk drives designed to utilize servo tracks for head position calibration and other There are effects such as being able to achieve compatibility with a disc drive device that employs a servo system.

[Brief explanation of drawings]

1 to 6 are for explaining the present invention in detail. FIG. 1 is a flowchart showing a basic algorithm for head position control, FIG. 2 is an explanatory diagram showing a typical example of a track format, FIG. 3 is a block diagram showing the control system, FIG. 4 is an explanatory diagram showing details of the recording tracks and servo tracks of the magnetic disk, FIG. 5 is an explanatory diagram showing the outline of the recording tracks and servo tracks of the magnetic disk, and FIG. 6
The figure is a block diagram showing an example of a servo circuit, and FIG. 7 is a partially cutaway perspective view of essential parts showing a specific example of a conventional disk drive device. 1... Magnetic disk, 2... Magnetic head, 3... DD motor, 8... Swing arm, 11... Stepping motor, 21
...Head amplifier, 22 ... Drive circuit, 23 ... Servo circuit, 24 ... Interface, 25 ... Controller, D ...・
...Data zone, F... Servo signal, O3
T, MST, IST... Servo track group, M
ST,,MS Tz,MS T a,MS
T4... Servo track, 0821. OSZ
! , MSZl, MSZ2. rsZ+, I SZZ...
... Servo zone, T ... Recording track, I
N.K. IN, ...internal index, ErN...
...External index, G, ...Gap 1,
G2... Gap 2, G,... Gap 3, G4... Gap 4, S... Sector.

Claims (1)

[Claims] In a recording medium drive device that writes or reads signals to or from a recording track on an information recording medium via a head device, a method for positioning the head device with respect to the recording track includes a servo drive in which servo information is written. When tracks are formed only at preset track positions on the information recording medium and read operations are performed continuously on one track, the head device is moved from the recording track to the servo track at the final gap position following the final sector. Move it and read the servo information from the servo track,
After that, the head device is returned to the recording track before the movement, and is positioned at a fine track position with respect to the recording track based on the read servo information, and then the head device is returned to the read operation before the movement from the final gap position. head positioning control method.