JP2004241082A - Eccentricity compensating method and system in disk servo writer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording disk in which eccentricity of a servo pattern is small even if the eccentricity is caused when a magnetic recording medium is loaded to the disk servo writer. <P>SOLUTION: The shape of the inner hole of the magnetic recording medium is measured, the center point of an inscribed circle of the inner hole is obtained, a reference pattern is magnetically formed in a circle state having a fixed radius outside a plotting region of the magnetic pattern on the magnetic recording medium with the obtained center point as a center. the magnetic recording medium 107 in which the reference pattern 121 is recorded is attached to a rotary shaft 433 of a disk servo writer through a medium holding base 441 provided with stages of two direction, a position of the reference pattern is followed by a reproducing head 443, variation of a voice coil current of a head stack assembly of the reproducing head is detected, the eccentricity quantity from the rotary shaft at the time of attaching the magnetic recording medium is calculated by variation of the current, and eccentricity is reduced by drive-controlling the two direction stages in accordance with this eccentricity quantity. After that, the magnetic pattern is recorded. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for writing a servo pattern used for detecting a position of a magnetic head, an ID pattern for identifying a disk, a program, and the like on a magnetic disk, and more particularly, to a method and a system for correcting eccentricity in a disk servo writer.
[0002]
[Prior art]
As a conventional example, a disk servo writer for writing a servo pattern will be described. FIG. 9 shows the entire structure of a conventional disk servo writer for writing head positioning information on a magnetic disk, and FIG. 10 is a diagram showing a main part of the disk servo writer as viewed from above.
[0003]
As shown in FIGS. 9 and 10, the disk servo writer includes a clock pattern disk 901 for writing and reading clock patterns, and a disk stack unit 905 in which one clock pattern disk and M magnetic disks 903 are stacked. A spindle motor 907 for rotating the disk stack unit at several thousand rpm, a clock pattern generator 909 for generating a clock pattern, a clock head 911 for writing a clock pattern on the clock pattern disk 901, and a clock head for positioning the clock head. A positioner 913, a servo pattern generator 915 for generating a servo pattern, and a magnetic recording head 917 for writing the servo pattern on the magnetic disk 903 are stacked. A rotary positioner 919 for rotating and positioning a servo pattern head (magnetic recording head) 917; a position detector 923 for detecting the position of the rotary positioner from a rotary encoder 921 built in the rotary positioner; It has a servo compensator 925 that calculates a servo compensation value from an error with the position, and a power amplifier (power amplifier) 927 that outputs a drive current for the rotary positioner 919 based on the servo compensation value.
[0004]
The operation of the disk servo writer will be described below. First, the clock head 911 records the clock pattern generated by the clock pattern generator 909 at an arbitrary radial position of the clock pattern disk 901 (indicated by 902 on the outermost circumference in FIG. 11).
[0005]
Next, the position of the rotary positioner 919 is detected by a position detector 923 by a rotary encoder 921 built in the rotary positioner 919, and an error between the detected position and the target position is rotary-rotated through a servo compensator 925 and a power amplifier 927. Feedback is provided to the positioner 919 so that each magnetic recording head 917 follows the target position.
[0006]
In this tracking state, the magnetic recording head 917 writes the servo pattern generated by the servo pattern generator 915 on the magnetic disk 903 in synchronization with the clock read from the clock pattern disk 901.
[0007]
[Patent Document 1]
JP, 2001-12420, A specification paragraph [0006]
[0008]
[Problems to be solved by the invention]
To mount the magnetic recording media 901 and 903 on the conventional disk servo writer as described above, the shaft 933 of the spindle motor 907 is inserted into the inner hole 931 of the magnetic recording medium, and is fixed by a disk fixing mechanism (not shown). However, since there is no gap between the inner hole 941 of the magnetic recording medium and the shaft 933 of the spindle motor, there is no gap between the center of the inscribed circle in the inner hole 931 of the magnetic recording medium and the shaft 933 of the spindle motor due to the gap. A shift occurs. This deviation amount has no regularity and is generated as a random amount. Similar deviation occurs when a magnetic recording medium 903 on which a magnetic pattern is recorded by a disk servo writer is assembled as an HDD (hard disk drive). .
[0009]
It suffices that these shifts occur in a direction that cancels out. However, since these shifts occur randomly as described above, in the worst case, the shifts are synergistic shifts. If the deviation is large, there is a problem to be solved that the position control of the magnetic head takes time and the data access time becomes long (see Patent Document 1).
[0010]
An object of the present invention is to solve the above-described problems, and even when there is an eccentricity when a magnetic recording medium is mounted on a disk servo writer, the magnetic recording medium is re-mounted by correcting by moving the stage, and an inner hole of the magnetic recording medium is formed. To realize an eccentricity correction method and an eccentricity correction device in a disk servo writer, which can record a servo pattern centered on the center point of an inscribed circle and can provide a magnetic recording disk with a small center deviation of the servo pattern. It is in.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following measures to measure the amount of eccentricity even when there is an initial eccentricity when mounting a magnetic recording medium on the axis of a spindle motor of a disk servo writer, It is characterized in that eccentricity is corrected by a stage in two directions and a servo pattern is recorded.
[0012]
(1) Formation of reference pattern a. By measuring the shape of the inner hole in the magnetic recording medium, the center point of the inscribed circle of the inner hole is obtained.
b. A reference pattern is magnetically formed outside the drawing area of the servo pattern or the like on the magnetic recording medium in a circular shape having a constant radius around the center point.
[0013]
(2) Grasp of eccentricity when mounted on disk servo writer a. By attaching the above magnetic recording medium to a disk servo writer and causing the read head provided on the disk servo writer to follow the reference pattern and detecting a change in the drive current of the rotary drive system of the head stack assembly of the read head Then, the deviation of the disk servo writer from the axis of the spindle motor when the magnetic recording medium is mounted is grasped.
[0014]
(3) Correcting the mounting displacement by moving the stage, and recording on a magnetic recording medium by a disk servo writer a. A two-way stage based on surface acoustic waves is provided on the holding base of the magnetic recording medium in the servo track writer, and the stage is moved so as to minimize the change in the drive current of the rotary drive system of the head stack assembly of the upper read head. To correct the eccentricity during initial mounting.
b. With the eccentricity corrected, the magnetic recording medium is completely fixed to the holding base, and the servo pattern is recorded.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
1 and 2 show configuration examples of writing and mounting a reference pattern on a magnetic recording medium to which the present invention is applied. FIG. 1 shows the overall configuration of the writing device, and FIG. 2 is a plan view of a main part of the writing device as viewed from above.
[0017]
As shown in FIGS. 1 and 2, a vacuum suction type disk holder 105 is provided at the tip of the shaft 103 of the spindle motor 101, and the magnetic recording medium 107 is mounted so as to substantially match the shaft 103 of the spindle motor. The magnetic recording medium 107 is closely fixed to the disk holder 105 by vacuum suction. A high-resolution sensor (CCD sensor) 111 for observing the end face position of the inner hole 109 is provided above the inner hole 109 of the magnetic recording medium 107, and is directly connected to the motor 101 while rotating the spindle motor 101. From the rotation angle signal output from the encoder 113 and the image signal output from the sensor 111, the image processing device 115 measures the end face position of the inner hole 109 with respect to the rotation angle, and obtains the polar coordinates at each point on the inner hole end face. .
[0018]
As a high-resolution measuring method for observing the end face position of the inner hole, for example, a method of measuring the end face position by digital processing from an image captured by the high-resolution CCD 111 or a method of measuring the reflected light of the laser light applied to the end face. A method of performing superposition with the reference light and measuring the end face position from the position of the interference fringe can be applied.
[0019]
In the image processing device 115, an inscribed circle is calculated by calculation with respect to the end face coordinate position of the inner hole 109 of the magnetic recording medium 107, and the center point of the inscribed circle is specified. With this center point as the origin, a magnetic recording head position command signal is output from the image processing device 115 to the magnetic recording head drive system 117, and the magnetic recording head 119 provided in the device records the magnetic recording medium 107 in a later step. The reference pattern 121 is written in a circle having a constant radius around the center point at a position outside the magnetic pattern region such as a servo pattern to be written.
[0020]
The reference pattern 121 must be a servo pattern capable of controlling the position of the magnetic reproducing head at a specific track position, for example, as shown in FIG. 3, reference numeral 301 denotes a position detection area where the reference pattern 121 is recorded, 303 denotes an address area, 305 denotes a gap area, 307 denotes a gray code area, and 309 denotes a clock area.
[0021]
FIG. 4 shows the entire structure of the servo track writer according to the present invention, and FIG. 5 is a view of the servo track writer as viewed from above. Here, reference numeral 401 denotes a clock pattern disk on which a clock pattern is recorded; 407, a spindle motor for simultaneously rotating the plurality of magnetic recording media 107 and the clock pattern disk 401; 411, a clock head for reading the clock pattern of the clock pattern disk 401; Is a servo pattern generator that generates a magnetic pattern such as a servo pattern, 417 is a magnetic recording head that records the pattern on the magnetic recording medium 107, 419 is a head stack assembly that holds the stacked magnetic recording heads 417, and 421 is a head stack. An encoder 423 for measuring the rotation angle of the assembly 419 and a head position 423 for detecting the clock position of the magnetic recording head 417 and the clock from the output of the encoder 421 and the output of the clock head 411. The clock detector 425 is a servo compensator that generates a compensation current corresponding to the difference (error) between the detected recording head position and the target value A. The servo compensator 427 is a head that reduces the error in the direction in which the error decreases according to the compensation current. A power amplifier that rotationally drives the stack assembly 419 and 433 are axes of the spindle motor 407.
[0022]
Reference numerals 441 to 457 denote constituent elements unique to the present invention. Reference numeral 441 denotes a vacuum suction mechanism for fixing the magnetic recording medium 107 to the shaft 433 of the spindle motor 407, and X and 441 for moving the magnetic recording medium 107. A medium holding base having both Y stages, 443 is a magnetic reproducing head for reading the above-described position detection reference pattern recorded on the magnetic recording medium 107, and 445 is rotating and positioning the stacked magnetic reproducing head 443. It is a head stack assembly. Reference numeral 447 indicates the position of the magnetic reproducing head 443 by detecting a change in the drive current (voice coil current) of the rotary drive system of the head stack assembly 445 when the magnetic reproducing head 443 tracks the track of the reference pattern 121. A read head position detecting unit 449 for detecting a servo compensator for outputting a voice coil current as a compensation value corresponding to an error between the detected read head position and the target value B, and 451 a voice coil from the servo compensator 449 A power amplifier that amplifies the current and supplies it to a voice coil (not shown) of the head stack assembly 445 that rotates and moves the magnetic reproducing head 443, thereby rotating and moving the magnetic reproducing head 443 to a position where the above error is eliminated.
[0023]
Reference numeral 453 denotes an encoder for detecting the rotation angle of the shaft 433 of the spindle motor 407 (that is, the rotation angle of the magnetic recording medium), and 455 inputs the rotation angle of the magnetic recording medium from the encoder 453 and the voice coil current from the servo compensator 449. An eccentricity calculating unit for calculating an eccentricity in the X and Y directions for each rotation angle of the magnetic recording medium 107, which corresponds to a deviation from the shaft 433 of the spindle motor 407 of the disk servo writer when the magnetic recording medium 107 is mounted; Reference numeral 457 drives the X and Y stages (601 to 604 in FIG. 6) on the medium holding base 441 in accordance with the eccentricity signals in the X and Y directions output from the eccentricity calculating unit 455, and An X, Y stage control unit that moves the recording medium 107 to a direction and a position where the eccentricity is eliminated.
[0024]
The servo track writer of the present invention shown in FIGS. 4 and 5 is different from the conventional servo track writer shown in FIGS. 9 and 10 in that a magnetic read head 443 for measuring the eccentricity of the magnetic recording medium 107 and a magnetic read head 443 are provided. The head position control systems 447 to 457 are provided, and the medium holding base 441 of the magnetic recording medium 107 is further provided with a vacuum suction mechanism and X and Y stages.
[0025]
In FIG. 4, for simplification of the drawing, only one input line for the magnetic recording head 417 and the medium holding base 441 and only one output line for the magnetic reproducing head 443 are shown. The output lines are individually connected to all the corresponding magnetic recording heads 417, medium holding bases 441, and magnetic reproducing heads 443 mounted on the servo track writer. The processing of the signals transmitted through the plurality of input lines or output lines may be a switching process using a switch function, but may be realized by a parallel simultaneous process.
[0026]
FIG. 6 shows a structure of a medium holding base 441 functioning as a magnetic recording medium fixing mechanism of the servo track writer shown in FIG. 4, and FIG. 7 shows a state where the medium holding base 441 holds the magnetic recording medium 107. As shown in FIG. 6, the medium holding base 441 has a vacuum chuck including two surface acoustic wave stages 601 to 604 having adjustable holding positions and a vacuum suction hole 605 for holding the disk (magnetic recording medium) 107. Is provided. More specifically, the medium holding base 441 is provided with fine movement stages 601 to 604 each composed of an ultrasonic vibrator divided into four in the X and Y angle directions, and the surface of the ultrasonic vibrator is provided with an IDT (Inter). An electrode (interdigital electrode) of a Digital Transducer (interdigital electrode surface acoustic wave transducer) is provided, two specific opposing electrodes are used for X-direction movement, and two orthogonal electrodes are used for Y-direction movement, By adjusting the phase of the resonance frequency applied to the two IDTs, the surface acoustic wave generated on the surface of the ultrasonic vibrator (which may be any of a piezoelectric vibrator, an electrostrictive vibrator, and a magnetostrictive vibrator) becomes a traveling wave. Alternatively, it becomes a backward wave and plays a role of a stage for moving the magnetic recording medium 107. Here, 601 is an X-direction surface acoustic wave stage A, 602 is an X-direction surface acoustic wave stage B, 603 is a Y-direction surface acoustic wave stage A, and 604 is a Y-direction surface acoustic wave stage B.
[0027]
One movement of the magnetic recording medium 107 by the surface acoustic wave stages 601 to 604 is a movement amount of about several nanometers, which is caused by vacuum suction by a number of vacuum suction holes 605 to be described later. This is because the ultrasonic transducer on the base 441 comes into close contact with the ultrasonic transducer, which is equivalent to applying a brake to the lateral movement, and the desired movement can be precisely achieved by repeating several times.
[0028]
On the other hand, the medium holding base 441 also serves as a vacuum chuck as a disk holder, and a number of vacuum suction holes (air suction holes) are provided on the surface acoustic wave stages 601 to 604 as ultrasonic vibrators provided on the medium holding base 441. 605 is provided, and the gap between the surface acoustic wave stage 601 to 604 and the magnetic recording medium 107 is set to a negative pressure by suction, so that the magnetic recording medium 107 is ultrasonically oscillated as shown in FIG. Is tightly fixed to the medium holding base 441 provided with.
[0029]
Next, the entire operation of the servo track writer will be described with reference to FIGS. 4 and 5 again.
[0030]
The magnetic recording medium 107 on which the reference pattern 121 is recorded as described with reference to FIGS. 1 and 2 is mounted on the medium holding base 441 provided with the above-described moving / fixing mechanism, and the above-described vacuum chuck function is used. The magnetic recording medium 107 is fixed to the medium holding base 441, and the magnetic recording medium 107 is rotated at a predetermined rotation speed by the spindle motor 407 via the rotating shaft 433 to which the medium holding base 441 is fixed.
[0031]
The magnetic reproducing head 443 provided on the servo track writer must be controlled so as to follow a specific track of the reference pattern 121 provided on the magnetic recording medium 107 in advance. Therefore, the position of the magnetic reproducing head 443 is detected by detecting a change in the drive current (voice coil current) of the rotary drive system of the head stack assembly 445 in the head position detection unit 447, and the coordinate value of the detected position is set in advance. A voice coil current is generated as a servo compensation amount by the servo compensator 449 from the difference (error) from the coordinate value B of the target position. By supplying the voice coil current to a rotating voice coil (not shown) of the magnetic reproducing head 443 via the power amplifier 451, feedback control of the magnetic reproducing head 443 is achieved.
[0032]
A voice coil output from the servo compensator 449 in the eccentricity calculator 455 to determine in which direction and how much the reference pattern 121 of the magnetic recording medium 107 is eccentric with respect to the axis 433 of the spindle motor 407 of the servo track writer. Based on the current value and the rotation angle of the magnetic recording medium output from the encoder 453 of the spindle motor 407, calculation is performed for each rotation angle. Output to control unit 457.
[0033]
FIG. 8 shows current waveforms of the reproducing head driving voice coil when the reference pattern 121 is eccentric with respect to the axis 433 of the spindle motor 407 of the servo track writer and when it is not eccentric. FIG. 8A shows a current waveform of the voice coil when there is no eccentricity, and FIG. 8B shows a current waveform of the voice coil when there is eccentricity.
[0034]
As shown in FIG. 8B, when the reference pattern 121 is eccentric with respect to the axis 433 of the spindle motor 407 of the servo track writer, the current change of the reproducing head driving voice coil increases. An encoder 453 that can measure the rotation angle is provided on the shaft 433 of the spindle motor 407. The eccentricity calculation unit 455 uses the measured value of the encoder 453 to generate the voice coil for driving the reproducing head at each rotation angle. A difference value of the current with respect to the current average value (indicated by a broken line in FIG. 8B) is obtained, and this difference value is separated into the X and Y components of the stages 601 to 604 of the medium holding base 441, and is separated. The eccentricity signal is output to the X and Y stage control unit 457 as an eccentric signal in the X and Y directions. The X, Y stages 601 to 603 of the surface acoustic wave type provided on the medium holding base 441 are minimized so as to minimize the change in the driving current. Dynamic and, thereby subjected to the movement of the magnetic recording medium 107, to correct the eccentricity at the time of initial attachment.
[0035]
As described above, by incorporating the detection of the voice coil current and the stage movement as a feedback system, finally, the eccentricity of the reference pattern 121 with respect to the spindle motor shaft 433 is controlled as shown in FIG. It is possible to reduce the amount to the amount caused by system noise. After the eccentricity of the clock pattern disk 401 is corrected in the same manner (the control system circuit is not shown in FIG. 4), the medium is removed by vacuum suction with the eccentricity corrected in this manner. The magnetic recording medium 107 is completely fixed to the holding base 441, and a magnetic pattern such as a servo pattern is magnetized by the servo pattern generator 415 via the magnetic recording head 417 based on the clock read from the clock pattern disk 401 by the clock head 411. Writing is performed on the recording medium 107.
[0036]
The control system for correcting the eccentricity of the clock pattern disk 401 includes a clock head position detector, a servo compensator, a power amplifier, an eccentricity calculator, an X and Y stage control as in the case of the magnetic reproducing head 443. And operate similarly. If this control system is also written in the drawing, the drawing becomes complicated, so that it is not shown.
[0037]
(Other embodiments)
Although a preferred embodiment of the present invention has been described by way of example, the embodiment of the present invention is not limited to the above-described embodiment. Various modifications such as replacement, change, addition, increase / decrease in number, and change in shape are all included in the embodiments of the present invention.
[0038]
For example, although a magnetic recording head is used to magnetically form the reference pattern in the reference pattern forming step, it may be magnetically transferred from a master disk in which the reference pattern is magnetically embedded. Also, a medium holding base using an ultrasonic vibrator and a vacuum chuck has been exemplified as a holder suitable for minute movement and fixing of a magnetic recording medium. However, the present invention is not limited to this, and may be, for example, a biaxial orthogonal stage. . Also, a disk servo writer that processes a large number of magnetic recording media at one time has been illustrated, but the present invention can of course be applied to a disk servo writer that processes magnetic recording media one by one.
[0039]
【The invention's effect】
As described above, according to the present invention, even if the magnetic recording medium is mounted on the disk servo writer, even if there is eccentricity, the magnetic recording medium is remounted by correcting by moving the stage, and the inscribed circle in the inner hole of the magnetic recording medium is obtained. And a magnetic recording disk with a small center shift of the servo pattern can be provided.
[Brief description of the drawings]
FIG. 1 is a side view with a block diagram showing the configuration of a device for writing a reference pattern onto a magnetic recording medium according to the present invention in a partially cut-away cross section.
FIG. 2 is a plan view of a main part of the writing device of FIG. 1 as viewed from above.
FIG. 3 is a schematic diagram showing a shape of a reference pattern according to the present invention.
FIG. 4 is a side view with a block diagram showing a circuit configuration and a side structure of a control system of the servo track writer according to the present invention.
5 is a plan view of the servo track writer of FIG. 4 as viewed from above.
FIG. 6 is a plan view showing a structure of a medium holding base of a magnetic recording medium fixing mechanism in the servo track writer according to the present invention.
FIG. 7 is a side view showing a state where a magnetic recording medium is held on the medium holding base of FIG. 6;
8A and 8B show current waveforms of a voice coil for driving a reproducing head of a servo track writer according to the present invention, wherein FIG. 8A is a waveform diagram showing a current waveform of a voice coil when there is no eccentricity, and FIG. FIG. 4 is a waveform diagram showing a current waveform of the voice coil of FIG.
FIG. 9 is a side view with a block diagram showing a circuit configuration and a side structure of a control system of a conventional disk servo writer.
FIG. 10 is a plan view of the conventional disk servo writer of FIG. 9 as viewed from above.
FIG. 11 is a back view showing a clock pattern in the clock pattern disk of FIG. 9;
[Explanation of symbols]
101 Spindle motor 103 Spindle motor shaft 105 Vacuum suction type disk holder 107 Magnetic recording medium 109 Inner hole 111 of magnetic recording medium High resolution sensor (CCD sensor)
113 Encoder 115 Image processing device 117 Magnetic recording head drive system 119 Magnetic recording head 121 Reference pattern 301 Position detection area 303 Address area 305 Gap area 307 Gray code area 309 Clock area 401 Clock pattern disk 407 Spindle motor 411 Clock head 415 Servo pattern generator 417 Magnetic recording head 419 Head stack assembly 421 Encoder 423 Head position & clock detector 425 Servo compensator 427 Power amplifier 433 Spindle motor shaft 441 Medium holding base 443 provided with both vacuum suction mechanism and X and Y stages Magnetic reproducing head 445 Head stack assembly 447 Reproduction head position detector 449 Servo compensator 451 Power amplifier 453 Encoder 4 55 Eccentricity calculator 457 X, Y stage controller 601 X-direction surface acoustic wave stage A
602 X direction surface acoustic wave stage B
603 Y direction surface acoustic wave stage A
604 Y direction surface acoustic wave stage B
605 Vacuum suction hole 901 Clock pattern disk 902 Clock pattern 903 Magnetic disk 905 Disk stack unit 907 Spindle motor 909 Clock pattern generator 911 Clock head 913 Clock head positioner 915 Servo pattern generator 917 Magnetic recording head 919 Rotary positioner 921 Encoder 923 Position detector 925 Servo compensator 927 Power amplifier

Claims (11)

The shape of the inner hole of the magnetic recording medium on which the magnetic pattern is recorded by the disk servo writer is measured, the center point of the inscribed circle of the inner hole is obtained, and the obtained center point is used as a center on the magnetic recording medium. A reference pattern forming step of magnetically forming a reference pattern in a circular shape with a constant radius outside the drawing area of the magnetic pattern;
The magnetic recording medium on which the reference pattern is recorded is mounted on a rotating shaft of a disk servo writer via a holder having a two-axis stage, and the position of the reference pattern is determined by a reproducing head provided on the disk servo writer. A change in the drive current of a rotary drive system that drives the rotation of the head stack assembly of the read head, and detects the change in the drive current from the rotation axis of the disk servo writer when the magnetic recording medium is mounted. An eccentricity grasping step for obtaining the eccentricity of
By driving the two-axis stage provided on the holder according to the eccentricity, the mounting position of the magnetic recording medium is moved, and the mounting displacement that minimizes the change in the driving current of the rotary drive system is reduced. An eccentricity correction method comprising: a correction step. The eccentricity correction method according to claim 1, wherein the two-axis stage provided on the holder is a two-axis orthogonal stage. 3. The eccentricity correction method according to claim 2, wherein the two-axis orthogonal stage is a two-way stage using surface acoustic waves. 4. The eccentricity correction method according to claim 1, wherein the stage has a plurality of vacuum suction holes for fixing the magnetic recording medium. 2. The eccentricity correction method according to claim 1, wherein the step of forming the reference pattern in the step of forming the reference pattern is performed using a magnetic recording head. The eccentricity correction method according to claim 1, wherein the magnetically forming the reference pattern in the reference pattern forming step is performed by magnetic transfer from a master disk in which the reference pattern is magnetically embedded. A magnetic pattern recording step of completely fixing the magnetic recording medium to the holder and recording a servo pattern or another magnetic pattern in a state where the eccentricity has been corrected by performing the mounting displacement correction step. The eccentricity correction method according to claim 1, wherein The shape of the inner hole of the magnetic recording medium on which the magnetic pattern is recorded by the disk servo writer is measured, the center point of the inscribed circle of the inner hole is obtained, and the obtained center point is used as a center on the magnetic recording medium. A reference pattern forming means for magnetically forming a reference pattern in a circular shape with a constant radius outside the drawing area of the magnetic pattern,
The magnetic recording medium on which the reference pattern is recorded is mounted on a rotating shaft of a disk servo writer via a holder having a two-axis stage, and the position of the reference pattern is read by a reproducing head provided on the disk servo writer. In the following state, a change in the drive current of a rotary drive system that drives the rotation of the head stack assembly of the read head is detected, and the change in the drive current causes the disk servo writer to operate when the magnetic recording medium is mounted. Eccentricity grasping means for obtaining the eccentricity from the rotation axis,
By driving the two-axis stage provided on the holder according to the eccentricity, the mounting position of the magnetic recording medium is moved, and the mounting displacement that minimizes the change in the driving current of the rotary drive system is reduced. An eccentricity correction system comprising a correction unit. The reference pattern forming means,
Imaging means for imaging the shape of an inner hole of a magnetic recording medium on which a magnetic pattern is recorded by a disk servo writer;
The shape of the inner hole of the magnetic recording medium is measured based on the image signal output from the imaging means, and the center point of the inscribed circle of the inner hole is obtained. Image processing means for outputting a magnetic recording head position command signal for magnetically forming a reference pattern in a circular shape with a constant radius outside a drawing area of a magnetic pattern on a recording medium,
In response to the magnetic recording head position command signal, the reference pattern is magnetically transferred via the magnetic recording head to the reference pattern in a circular shape having a constant radius around the center point and outside the drawing area of the magnetic pattern on the magnetic recording medium. The eccentricity correction system according to claim 8, further comprising a magnetic recording head drive system to be formed. The eccentricity grasping means,
The magnetic recording medium on which the reference pattern is recorded is mounted on the holder and rotated, and in a state where the reproduction head follows the position of the reference pattern, the rotation driving system of the head stack assembly of the reproduction head is used. Driving current detecting means for detecting a driving current;
Servo compensation means for outputting a difference value between the detected drive current and a preset target value as a control drive current,
Power means for applying the control drive current to a rotary drive system of the head stack assembly;
A change in the control drive current is detected by a difference from the average value, and the amount of eccentricity of the disk servo writer from the rotation axis when the magnetic recording medium is mounted is calculated for each rotation angle based on the detected change amount. The eccentricity correction system according to claim 8 or 9, further comprising an eccentricity amount calculating means for outputting an eccentricity signal in X and Y directions based on the calculated result. 2. The apparatus according to claim 1, wherein the mounting displacement correcting unit is an X, Y stage control unit that drives the biaxial stage provided on the holder in accordance with the X, Y direction eccentricity signal. The eccentricity correction system according to any one of 8 to 10.

Images