JP2003257138A - Eccentricity evaluation method, servo pattern writer and manufacturing system for magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a servo writer having an eccentricity measuring function capable of easily verifying the centering accuracy of a disk at the time of servo pattern write at a low cost. <P>SOLUTION: A demodulation circuit for reading a servo pattern (track) partially written beforehand (b) in a disk group biased to a spindle hub 4 (a) after centering (c) and converting it to the information of a track position (d) is added to the servo writer. The position information is analyzed, the deviation (eccentricity) in the radial direction of a disk center is obtained by an arithmetic operation, compared with a stipulated value and verified (e) and then a normal servo pattern is written in a centering state where the eccentricity is equal to or less than a prescribed predetermined value. The centering accuracy of matching the center of a magnetic disk medium (disk) and the center of the servo track in the process of writing the servo pattern to the disk group altogether before incorporation to a magnetic disk device is improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentricity evaluation technique and a servo pattern writing technique, and is particularly effective when applied to a manufacturing technique of a servo writer and a magnetic disc device for writing a servo pattern on a magnetic disc medium. Regarding technology.

[0002]

2. Description of the Related Art Conventionally, servo information for positioning a head is written on a disk which is a recording medium of a magnetic disk device. Writing to this disk medium (Servo Track Writer: servo writer) is performed with the magnetic disk device completely assembled, but this type of servo writer has a high density of the magnetic disk device and a narrow track pitch. As a result, the number of write tracks is increased, which increases the servo write time, and the number of servo writers required to compensate for the decrease in production capacity is rapidly increasing. Furthermore, due to the narrowing of the data track pitch of the product, the servo track pitch by the servo writer is currently ½ to 1 /
Since it is necessary to write a 3-width servo pattern, the writing accuracy is approaching the limit. For example, at present, 55 KT
The number of writing tracks of a PI (track / inch) magnetic disk device is about 100,000, and the feed pitch of a servo writer for writing in the radial direction is about 150 nanometers (nm). This corresponds to 1/3 of the data track pitch of the magnetic disk device. Further, the writing time for this purpose requires 20 minutes / unit. Further, when the track density increases to 2 times or 4 times in the near future, the writing time further increases in proportion to this and the track pitch is inversely proportional. Positioning accuracy is required.

Therefore, as a means for solving both of these technical problems, a magnetic disk medium is a magnetic disk medium as a method for dealing with a more accurate servo information writing method and a shortening of the writing time per disk. The servo information is written simultaneously on a large number of discs while suppressing the vibration of the head actuator by using a high-precision spindle motor in the state of a single disc before it is installed in the disk device, and after writing the servo information, each magnetic disk A servo writer that is built into the spindle of the device is used. Japanese Patent Laid-Open No. 9-32000
Japanese Unexamined Patent Publication No. 2 discloses an assembling method that does not cause eccentricity of a disk medium at the time of writing and assembling a disk, which is a problem in this type of servo writer.

Also, a method of fixing the magnetic disk medium to the spindle hub so that the eccentricity error is reduced,
It is disclosed in Japanese Patent Laid-Open No. 2001-101741.
Further, in Japanese Unexamined Patent Publication No. 11-185445, a gap amount between a disc and a hub is measured from a rod movement amount when a plurality of sets of rods in X and Y directions are biased in both directions, and a target movement amount of the rod. A centering method and apparatus for determining (X1 + X2) / 2 (a half amount of the gap) has been proposed.

In the method disclosed in Japanese Unexamined Patent Publication No. 9-320002 of the prior art, the center of rotation of the disk medium at the time of writing servo information and the center of rotation at the time of incorporation into the device are made to coincide with each other as much as possible. Although the reference mark (a part, hole, groove, etc. where film is not formed) attached to the end is used, for the confirmation method of the center position itself,
Not mentioned.

[0006] Further, Japanese Patent Laid-Open No. 2001-1017 of the prior art
In the method disclosed in Japanese Patent No. 41, the disk gap is uniformly positioned by forming a fluid (air) film between the inner peripheral side surface of the disk medium and the side surface of the spindle hub (shaft). The eccentricity is evaluated by confirming the shaft runout of the outer diameter of the disc rotation by the non-contact sensor, so the eccentricity is obtained accurately due to the influence of the disc outer diameter tolerance and the concentricity with the inner diameter. In addition, there is a drawback that the sensor cannot be attached when a large number of discs are laminated.

Further, in Japanese Patent Laid-Open No. 11-185445, as a method for verifying whether or not centering is correctly performed, an image around a mark previously attached to the inner peripheral edge of the disk after centering is optically detected. Although a method of measuring the centering accuracy by matching comparison with an image when the centering has been completed is described, a mark and a detection optical system are required.

[0008]

Generally, in a manufacturing process of a system in which servo information is simultaneously written on a large number of discs in a single-disc state before the magnetic disc medium is assembled in a magnetic disc device, a magnetic disc is used. In the adjustment (adjustment) process (ETF: error track format process) in the post-process (test process) after the device is assembled, unique adjustment (servo gain adjustment, head center deviation, sense current adjustment, etc.) for each magnetic disk device is performed. It is necessary to measure the sector time interval (Ts) divided in the circumferential direction of the write servo pattern while performing the same phase component correction, etc.,
The eccentricity amount ΔR is calculated from the fluctuation value ΔTs by the following equation. This sector time interval measurement was originally carried out to learn and average fluctuations in the rotation accuracy of the spindle motor due to vibrations in the circumferential direction of the track. That is, the amount of eccentricity is ΔR = RΔTs / Ts. Where R is
The disk radius value at the middle and outer circumference track positions, Ts is the sector time interval value, which is determined by the disk rotation speed (rpm) and the number of sectors. In the case of 4200 rpm and 108 sectors, the sector time interval value Ts = 60 / rpm / sector Number = 132 μs.

In the eccentricity amount measurement by the sector time interval measurement, the sum of the eccentricity amount at the time of servo writing and the eccentricity amount at the time of replacement of the written disk is obtained, so that the eccentricity amount at the time of servo writing and after the disk is assembled. However, if the eccentricity amount found in the test process of the subsequent process becomes a large eccentricity defect, it is returned to the previous process and re-executed. It has a drawback that the turnaround time becomes long because it is sent to repair for assembly or re-servowritten.

An object of the present invention is to provide a spindle motor shaft and a circle when a servo write is performed on the magnetic disk medium of the magnetic disk drive outside the magnetic disk drive, and when a disk on which a servo pattern has been written is incorporated in the magnetic disk drive. Align the center of the plate on the nanometer order (centering)
(EN) Provided are a servo write device and a manufacturing system having an eccentricity amount measuring function, which can easily and inexpensively verify whether or not centering has been performed accurately by measuring the eccentricity amount immediately after the operation. .

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention partially servo-writes a disk in a state where it is offset, and then after centering the disk,
After reading the servo pattern that was written previously, from the amplitude voltage value of the position signal pattern and the value of the position sensitivity measured in advance, calculate the movement amount or eccentricity amount of the disk by calculation and compare and verify with the specified value, The regular servo pattern is surely written.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the configuration of a servo pattern writing apparatus for carrying out an eccentricity amount evaluation method according to an embodiment of the present invention, and FIG. 2 is an eccentricity amount exemplified in FIG. It is an external view which shows the mechanism part of the servo writer which has a measuring means.

In this embodiment, a servo writer having an eccentricity amount measuring means for centering and assembling a magnetic disk medium (disk) on the servo writer and then measuring and verifying the disk center will be described.

The servo pattern writing apparatus (servo writer) of the present embodiment comprises a mechanical section built on a stone surface plate 15 and an overall control section 6 for controlling this mechanical section.

As illustrated in FIGS. 1 and 2, the mechanism portion of the servo writer according to the present embodiment is supported on the stone surface plate 15 by the spindle motor 3 and the spindle hub 4 of the spindle motor 3. The VCM assembly 14 movably provided in the radial direction of the magnetic disk medium 1 and fixed at an arbitrary position by the lock assembly 21, and the head actuator mechanism unit 2 supported by the VCM assembly 14.
And a positioner 12 that positions the read / write head 25 by contacting the head actuator mechanism section 2.

A shroud 20 is arranged at a position facing the VCM assembly 14 with the magnetic disk medium 1 supported by the spindle hub 4 interposed therebetween.

Further, in a direction orthogonal to the direction in which the VCM assembly 14 and the shroud 20 face each other, a return mechanism including a biasing mechanism 16 and a return pin 18 with a plurality of magnetic disk media 1 supported by a spindle motor 3 interposed therebetween. 17 are arranged. A plurality of magnetic disk media 1 are stacked on a spindle hub 4 of a spindle motor 3 via a spacer or the like and fixed by a clamp 5.

The read / write head 25 is an R / WIC1.
3, a servo pattern writing unit (STW unit) 7 and a position demodulating unit 8 which will be described later are connected via a buffer 11.

On the other hand, the overall control section 6 comprises a servo pattern writing section (STW section) 7 and a position demodulation section 8.

The servo pattern writing section (STW) 7 is
Generation of a servo pattern write signal a for writing a servo pattern to a plurality of magnetic disk media 1 from the read / write head 25 via the buffer 11 and the R / WIC 13 (also used for the head read signal c later). ), A VCM control section 71 for sending a head feed signal b to a positioner 12 attached to a head actuator mechanism section 2 for positioning the head at a write track position of the pattern, The magnetic disk medium 1 includes a spindle control unit 72 for sending a rotation control signal of the spindle motor 3 for writing data on the entire circumference of each track of the magnetic disk medium 1.

The position demodulation section 8 includes a demodulation processing circuit 8
1, the D / A converter 82, the timing control circuit 83, etc., and the track position information of the servo pattern written on the magnetic disk medium 1 is read / write head 25, R.
/ WIC13 and the buffer 11 are read, the head read signal c is analyzed, and the amount of eccentricity is measured.

The position demodulator 8 has a waveform observing device (OSC) 9 used for monitoring the analog position signal e of the read pattern output from the D / A converter 82.
Are connected.

The servo pattern writing section (STW section) 7 and the position demodulating section 8 are connected to a control computer (PC) 10 for controlling the functions of both of them from the outside.

The servo pattern writing unit (STW unit) 7 of the overall control unit 6 can use the existing structure of the conventional servo writer, and the position demodulating unit 8 for demodulating the track position of the head read signal c is the main unit. These are added in the embodiment and can be incorporated in the conventional servo pattern writing device (STW).

FIG. 3 is a modification of the control configuration of FIG. 1 and is another example of the position demodulation unit 8. The position demodulation unit 8 of FIG. 1 has a VCM (Voice Coil).
A motor) driver 84 and a switch 85 are built in. The position demodulator 8 of FIG. 3 can independently control the positioner 12 by the switch 85 set from the PC 10. This is used when the position demodulator 8 is externally attached. An example of the internal configuration of the circuit board of the position demodulation unit 8 of FIG. 3 is shown in FIG.
Shown in.

The position demodulation unit 8 uses the R / W channel 8
A 6 (IC) called PLL (Phase (Phase) for each sector
A timing control circuit 83 composed of a Lock Loop controls the acquisition time of the head read signal c, and a FPGA (Flexible Program) via a buffer 87, a multiplexer 88, and an A / D converter 89.
It is taken into the logic processing circuit of the rampable gate array 90.

The operation function of the FPGA is programmed in the download ROM 93 in advance. FPGA 90 and DSP (Digital Signal Proces)
data is transmitted / received by the local bus 95, and position bursts A, B, C, etc. in the servo pattern for each sector written by the servo writer shown in FIG.
An amplitude value A1 of the head read signal c (RDXY) of the D signal,
The positions of the position / position error signals A-B and C-D calculated from B1, A2, B2, A3, B3 ... Are calculated and the position signal d thereof is generated. The position signal d generated from this read head is demodulated into a position signal d capable of detecting whether the read position of the head is at the target on-track position (for example, A2-B2 = 0), and the local memory 92 The data for one round of each track or statistical processing is performed for each sector by the DSP and sent to the PC 10 via the serial interface 94. Also,
The analog position signal e is output to the waveform observing device 9 by the D / A converter 82. FIG. 6 shows an example of a two-phase sector servo pattern when two burst signals are written in one track by the servo writer, but the same processing can be performed even when there are three bursts or more. Further, in the position demodulation unit 8,
The VCM driver 84 that controls the positioning of the head is FP
GA90, D / A converter 82, attenuator (attenuator)
96 and power amplifier 97, VCM control signal is generated according to the program of DSP 91, and switch 8
With the setting of 5, the external positioner 12 can be directly driven.

Next, the operation procedure of centering will be described. As a centering method, a centering mechanism 16 and a returning mechanism 17 for centering are shown on the mechanism part of the servo writer in FIG. 2. The centering mechanism 16 corresponds to each magnetic disk medium 1. The displacement plate 19 is attached and pressed by spring control, and the return mechanism 17 is attached with a return pin 18 corresponding to each magnetic disk medium 1. The return pin 18 is air clamped inside the return mechanism 17.

For centering, the inner diameter side of the magnetic disk medium 1 is pressed against the spindle hub 4 in one direction on one side as shown in FIG. 8C by a constant amount (1/2 return amount) from the measured average value X by the return mechanism 17.
Then, the magnetic disk medium 1 is centered by pushing it back in the opposite direction. At this time, the spindle motor 3 is locked and is fixed to the spindle motor 3, and the spindle hub 4 in which the magnetic disk medium 1 and the spacer (not shown) can be detached and the magnetic disk medium 1 and the spacer are fixed to the spindle hub 4. The clamp 5 is clamped by air after centering.

Further, at the time of centering, the biasing mechanism 16
The return mechanism 17 and the return mechanism 17 independently advance as indicated by arrows f and g in FIG.
6 and the return mechanism 17 are retracted (arrow h shown in FIG. 2). The shroud 20 moves forward in order to reduce wind turbulence due to the rotation of the plurality of magnetic disk media 1 during servo writing, and is inserted between the magnetic disk media 1 corresponding to each magnetic disk media 1.

Next, a method of measuring the amount of eccentricity will be described. FIG. 8 is a conceptual diagram for explaining the outline of the processing procedure for measuring the amount of eccentricity according to the present embodiment. In the biased state of FIG. 8A, the servo track pattern servo-written partially or entirely on the entire surface as shown in FIG. 8B is eccentrically written, and the pattern written at this position is written. When the magnetic disk medium (disk) is returned in (c) with reference to the position of, when the servo track is read in this state (d), this movement amount (eccentricity) is demodulated by the position demodulation unit 8. The processing circuit 81 changes the amplitude voltage value of the position signal d. Thereby, (e) the amount of movement, that is, the amount of eccentricity can be verified.

The principle of eccentricity measurement according to the present embodiment will be described with reference to FIG. Heads corresponding to the track Tr-b after returning to 1/2 with respect to the servo tracks Tr-a, Tr-b, and Tr-c (dotted line) that are written in an eccentric state in FIG. 7A. The virtual servo track (solid line) written at the position is an eccentricity written servo track Tr-a, Tr-b, Tr-c (dotted line) at the intersection a,
The positions b, c ... Deviate from the center of the servo track. As shown in FIG. 7B, the head read position signal read at the head position from the center of the eccentric servo track at the time of biasing each point has an output voltage value of Tr-
The sine or cosine waveform extends over a, Tr-b, and Tr-c. In FIG.
After the partial write in (b), when the track is read out without returning the disc in that state, the demodulated position signal becomes constant with zero amplitude.

The amount of eccentricity is measured using the amplitude value of this position signal. In order to obtain the amount of eccentricity, it is first necessary to measure the position sensitivity at least once every time the head is replaced. FIG. 10 is a flowchart showing a processing procedure of position sensitivity measurement. In the partial writing of the servo pattern (step S1), the servo writer of FIG. 1 is used to write to the outer 100 tracks at the servo track pitch tp of the product specification, and then the heads of the first track 1 and the last track 100 are written. The voltage value of the position output is read (step S2) and detected by the position demodulator 8. At this time, two cosine waveforms as shown in FIG. 9 are detected as the head read position signal around the track.
Difference between both head position output voltage values (changed voltage value)
Δv is calculated (step S3), and the position sensitivity k [μm
/ V] = track pitch tp × 100 tracks / Δv is calculated (step S4). This value is 100 when written on the inner track position with each head and disk combination.
Even in the case of a track, the values are almost the same, and the value from one representative head is substituted. Alternatively, the average value for each head may be used. This value k is, for example, k
= 4.56 [μm / v].

Next, for the measurement of the amount of eccentricity, a processing procedure of the measurement is shown in a flow chart in FIG. The assembling mechanism 16 of the centering mechanism shown in FIG. 1 incorporates a plurality of discs (step S10) and then displaces / clamps the discs (step S10).
11) Partially write on the outer n tracks at the product-specific servo track pitch tp (step S1).
2) Servo write.

Next, the air clamp is removed and the return mechanism 17
Then, the plurality of discs are returned to a predetermined amount (1/2 of the gap amount) and centered / re-clamped (step S13). Then, the servo pattern of the already written outer peripheral one track is read out for each disk (step S14).

At this time, as a head read position signal for one track of the track detected by the position demodulation section 8, a cosine waveform as shown in FIG. 11 is read for each disk. One half of the change voltage value V _pp of the head output voltage value becomes the eccentric voltage value V _0p = V _pp / 2 on one side, and the position output voltage V _0p is measured (step S15). Based on this result and the position sensitivity k in step S4, the displacement amount (eccentricity) x of the disc is calculated by the calculation of x = k · V _0p [μm] to obtain the eccentricity after returning each disc (step). S1
6).

In step S18, the centering position of each disk is determined to determine whether the eccentricity amount x is within a specified value. If NG, the clamp is removed (step S2).
3) The process returns to the one-sided alignment (step S11), and the re-centering is tried.

In step S17, which precedes step S18, if the number of repeated retries is large (for example, the preset value m times is exceeded), it is rejected as a centering NG (step S22), and is analyzed or repaired for the cause of NG. It In this case, the conventional servo writer may be used for rewriting.

When it is verified that the centering has been correctly performed in step S18 and the result is OK, it is overwritten by a normal servo write (overall STW) (step S19),
Writing the servo pattern of the product is executed. After the writing of the discs is completed, the process proceeds to the next process of removing each disc (step S20) and assembling the product (step S21). The time required to measure the amount of eccentricity requires two rotations for the uptake calculation process, and is 1 minute or less when the rotation speed of the disk is 4200 rpm, which is shorter than the tens of minutes of the servo write time. It becomes possible to measure the quantity. Therefore, the throughput in the servo pattern writing process does not decrease.

FIG. 13 shows the relationship between the number of discs of the servo writer and the movement amount (eccentricity amount) of the eccentricity amount measurement of this embodiment. An eccentricity of each disc disk according to the present embodiment when a contact sensor (not shown) is attached to the center pin of the return pin 18 attached to the return mechanism 17 of FIG. 2 and the total return amount is moved by 22 μm. It is a quantity measurement result. According to this
Depending on the stacking position of each disk, the actual moving amount of 22 μm is ±
The error is 1.5 μm. Further, FIG. 14 shows the relationship between the measured eccentricity amount according to the present invention and the linearity of the disc movement amount by the contact type sensor, and the width of the linearity with the actual movement amount according to the position of each disc disc is about ± 2 μm. Become.

FIG. 4 shows a disk (magnetic disk medium 1) after a servo write is performed by using the position demodulating section 8 and the servo pattern writing section 7 having the demodulating means and the calculating means of the control configuration of FIG. After being installed in the device 22,
It is a figure which shows the embodiment of eccentricity amount measurement at the time of verifying the center of a disk. In this case, the magnetic disk device 22
The drive circuit section 23 is not mounted.

In the manufacturing process, the center (eccentricity amount) of the magnetic disk medium 1 in which the servo pattern has been written as shown in the magnetic disk device (HDD) assembly (step K4) shown in FIG. Be done. Servo pattern writing unit 7 and position demodulation unit 8
Also, by adding the VCM mechanism section 24 of the type in which servo writing is performed after the conventional disk assembly, it is possible to confirm this center (amount of eccentricity).

That is, the magnetic disk device 22 on which the written disk is mounted in the STW process (step K2) of the previous manufacturing process is mounted on the VCM mechanism unit 24, and the position demodulation unit 8 preliminarily manufactures the magnetic disk device. The position sensitivity measured by using the read / write head 25 of No. 22 is obtained, and then the servo pattern after centering is read to similarly measure the eccentricity amount of the magnetic disk medium.
Verification can be performed. In this case, the VCM mechanism unit 2
Reference numeral 4 is the same as a conventional servo writer mechanism that controls the head actuator mechanism 2 of the product by pushing it with a pin.

Also, when confirming the center with a servo writer of the type in which a servo pattern is written in a state where the disk has been assembled in the magnetic disk device, the position demodulation section 8 is added to the conventional STW section 7. With the above configuration, the read / write head 2 of the magnetic disk device 22 of the product is prepared in advance.
Using the position sensitivity measured in step 5, it is possible to measure the amount of eccentricity basically in the same manner as the processing procedure for measuring the amount of movement of the disk in FIG. The number of the plurality of discs is different, and is one or two (the number mounted on the magnetic disk device). in this case,
The VCM mechanism unit 24 can use the mechanism unit itself added to the conventional servo writer for the method of controlling while pressing the head of the product with the pin.

FIG. 15 is a diagram for explaining a manufacturing process of a magnetic disk device of a system in which servo information is simultaneously written on a large number of discs before the magnetic disk medium is incorporated into the magnetic disk device. This manufacturing process is roughly divided into an assembly work (K1 to K9) performed in a clean room and a test process (K10 to K13) outside the clean room after assembly.

Before the magnetic disk medium is assembled into the magnetic disk device, the eccentricity is measured by writing servo information on a large number of discs at the same time. In the adjustment (adjustment) process (ETF: error track format process) (step K11), a unique adjustment for each magnetic disk device (servo gain adjustment, head center deviation, sense current adjustment, in-phase component correction, etc.) By performing the measurement of the sector time interval (Ts) divided in the circumferential direction of the write servo pattern during the above, the eccentricity ΔR is obtained from the fluctuation value ΔTs by the following equation. Originally, this sector time interval measurement was performed to learn the fluctuations in the rotation accuracy of the spindle motor due to the vibration in the circumferential direction of the track, and to average them. When using a plug-in type servo writer,
It was necessary to confirm the measurement of the amount of eccentricity due to the replacement of the disks in this process.

That is, the eccentricity ΔR is ΔR = RΔTs / Ts
Required by. Here, Ts is a sector time interval value, which is determined by the disc rotation speed (rpm) and the sector number.
In the case of rpm, 108 sectors, sector time interval value Ts =
60 / rpm / number of sectors = 132 μs. R is
It is the disk radius value at the middle and outer track positions. In the eccentricity measurement by this sector time interval measurement, the sum of the eccentricity at the time of servo writing and the eccentricity at the time of replacement of the written disk can be obtained, so the eccentricity at the time of servo writing and after mounting the disk can be separated However, there is a drawback that the amount of eccentricity in each work process is not required, and the adjustment (ET
F) When the eccentricity amount found in the step (step K11) becomes a large eccentricity defect, it is returned to the previous step and rewriting is performed, or it is sent to repair for reassembly.
It had the drawback of a long turnaround time.

On the other hand, in the present embodiment, as described above, the servo write process (step K2) which is a pre-process of the magnetic disk device, or the replacement HDD of the disk on which the servo pattern has been written in the magnetic disk device is replaced. By performing the eccentricity amount measurement in the assembly process (step K4), the work can be completed in the same clean room, so that efficient production is possible.

The invention described in the claims of the present application is expressed as follows in a different way.

(1). In a servo pattern writing device according to a method of writing a servo pattern on a plurality of magnetic disk media, and incorporating the magnetic disk media on which the servo patterns have been written into a magnetic disk device, the disk is partially offset in advance. Servo write is performed on the disk, then the disk is centered, and then the demodulation means for reading the previously written servo pattern to the demodulation circuit, and the rotation 1 included in the read signal on one round of the position information of the read servo pattern. A normal servo pattern is obtained by calculating means for measuring the amplitude voltage value of the next component (periodic component) and obtaining the amount of movement or eccentricity of the disk by calculation, and means for comparing and verifying the calculated value and the specified value. A servo writer having means for measuring the amount of eccentricity of a magnetic disk medium, which is characterized by writing.

(2). In the eccentricity amount measuring means in the servo writer according to item (1), the amplitude voltage of the plurality of read position information is based on the read information of a plurality of track positions written in advance at a predetermined track pitch tp. From the change voltage value Δv of position sensitivity k = track pitch tp
Xn / Δv is calculated, and the position sensitivity k and the output voltage of the position information of the servo pattern read from the arbitrary track where the partial writing is performed after centering the disk where the partial writing is performed by offsetting the disk The servo writer according to item (1), which is an eccentricity measuring means for calculating a deviation x = k · V _0p in the radial direction of the disc center from the value V _0p .

(3). The demodulation means described in item (1) and the calculation means described in item (2) are configured inside a servo writer device of a system that writes a servo pattern in a state in which the disk medium is completely installed in the magnetic disk device. A servo writer having a magnetic disk medium eccentricity amount measuring means.

(4). Performing the eccentricity amount measuring means described in the items (1) and (2) in a servo writer process in an assembling process of the magnetic disk device or in a process of replacing a disk on which a servo pattern has been written on the magnetic disk device. Characteristic magnetic disk device manufacturing system.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

[0056]

The eccentricity amount of the magnetic disk medium in the servo pattern writing step is measured by demodulating and utilizing the servo pattern written by the servo writer.
There is a merit that it can be realized at low cost.

Even when writing a servo pattern and assembling a magnetic disk medium into a magnetic disk device (HDD), a true center deviation (amount of eccentricity) can be detected, which facilitates alignment of the center of the magnetic disk medium. Servo writing is possible near the concentric axis. This allows
A magnetic disk device having a high recording density and good swing (RRO) performance synchronized with the number of rotations can be manufactured with high yield.

Since the quality of the eccentricity can be determined in the assembly process, it is not necessary to measure the amount of eccentricity in the adjusting process (ETF process) in the conventional post-process outside the clean room.
Even if a large eccentricity failure occurs, a quick
The magnetic disk device can be manufactured in turnaround time.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a servo pattern writing device that implements an eccentricity amount evaluation method according to an embodiment of the present invention.

FIG. 2 is an external view showing a mechanical portion of a servo pattern writing device having an eccentricity amount measuring means exemplified in FIG.

FIG. 3 is a conceptual diagram showing a modified example of the configuration of a servo pattern writing device that implements an eccentricity amount evaluation method according to an embodiment of the present invention.

FIG. 4 is a conceptual diagram when an eccentricity amount evaluation method according to an embodiment of the present invention is applied to a step of verifying centering when a magnetic disk medium after servo writing is incorporated into a magnetic disk device.

FIG. 5 is a block diagram showing an example of a configuration of a position signal demodulation processing circuit in a servo pattern writing device that implements an eccentricity amount evaluation method according to an embodiment of the present invention.

FIG. 6 is a conceptual diagram showing an example of a servo pattern read position signal from a magnetic disk device used in an eccentricity amount evaluation method according to an embodiment of the present invention.

7A and 7B are a conceptual diagram and a diagram for explaining the principle of eccentricity measurement in the eccentricity evaluation method according to an embodiment of the present invention.

8A to 8E are conceptual diagrams for explaining an outline of a processing procedure of eccentricity amount measurement in the eccentricity amount evaluation method according to the embodiment of the present invention in process order.

FIG. 9 is a diagram illustrating the position sensitivity of a head read position signal for one round of a track used in an eccentricity amount evaluation method according to an embodiment of the present invention.

FIG. 10 is a flowchart showing an example of a processing procedure of position sensitivity measurement in the eccentricity amount evaluation method according to the embodiment of the present invention.

FIG. 11 is a diagram showing a waveform of a head position output voltage after the magnetic disk medium is offset and moved by a certain amount in the eccentricity amount evaluation method according to the embodiment of the present invention.

FIG. 12 is a flowchart showing a processing procedure for measuring a disc movement amount (eccentricity amount) in the eccentricity amount evaluation method according to the embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of the relationship between the number of discs and the movement amount (eccentricity amount) obtained by measuring the eccentricity amount in the servo pattern writing device according to the embodiment of the present invention.

FIG. 14 is a diagram illustrating an example of the relationship between the eccentricity amount measurement value and the linearity of the disc movement amount by the contact sensor in the servo pattern writing device according to the embodiment of the present invention.

FIG. 15 is a flowchart illustrating an example of a manufacturing process of a magnetic disk device to which the eccentricity amount evaluation method and the servo pattern writing device according to the embodiment of the present invention are applied.

[Explanation of symbols]

1 ... Magnetic disk medium, 2 ... Head actuator mechanism part, 3 ... Spindle motor, 4 ... Spindle hub, 5 ...
Clamp, 6 ... Overall control unit, 7 ... Servo pattern writing unit (STW unit), 8 ... Position demodulation unit, 9 ... Waveform observation device, 10 ... Control computer (PC), 11 ... Buffer, 12 ... Positioner, 13 ... Read / write IC,
14 ... VCM (Voice Coil Motor) assembly, 15 ... Stone surface plate, 16 ... Offset mechanism, 17 ... Return mechanism, 18 ... Return pin, 19 ... Offset plate, 20 ... Shroud, 21 ... Lock assembly, 22 ... Magnetic Disk device HDD, 23 ... Drive circuit section, 24 ... VCM mechanism section, 25 ... Read / write head, 71 ... VCM control section,
72 ... Spindle control unit, 73 ... Pattern / clock generation unit, 81 ... Demodulation processing circuit, 82 ... D / A converter, 83
... Timing control circuit, 84 ... VCM driver, 85 ...
Switch, 86 ... R / W channel, 87 ... Buffer, 88
... multiplexer, 89 ... A / D converter, a ... servo pattern write signal, b ... head feed signal, c ... head read signal, d ... position signal, e ... analog position signal, 90 ...
FPGA (Flexible Programmable)
e Gate Array, 91 ... DSP (Digi)
tal Signal Processor), 92 ...
Local memory, 93 ... Download ROM, 94 ...
Serial interface, 95 ... Local bus, 96
… Attenuator, 97… Power amplifier.

Continued front page    (72) Inventor Kenji Tomita             2880 Kozu, Odawara City, Kanagawa Stock Association             Company Hitachi Ltd. Storage Division (72) Inventor Yoichi Kusaya             Hitachi, 781, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Computer Equipment Co., Ltd. (72) Inventor Katsumi Watanabe             2880 Kozu, Odawara City, Kanagawa Stock Association             Company Hitachi Ltd. Storage Division (72) Inventor Hiroshi Kawaguchi             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Inside the Hitachi, Ltd. production technology laboratory (72) Inventor Shizuo Yamazaki             2880 Kozu, Odawara City, Kanagawa Stock Association             Company Hitachi Ltd. Storage Division (72) Inventor Hiroshi Asao             2880 Kozu, Odawara City, Kanagawa Stock Association             Company Hitachi Ltd. Storage Division F term (reference) 5D096 AA03 DD06 DD08 EE03 KK01                       WW02 WW04 WW07 WW08

Claims (5)

[Claims] 1. A step of partially writing a servo pattern in a state where a magnetic disk medium is offset in advance; a step of centering the magnetic disk medium, and then reading the partially written servo pattern; Rotation 1 included in the read signal for one round
Measuring the amplitude voltage value of the next component (periodic component) and calculating the amount of movement or eccentricity of the magnetic disk medium by the centering, and redoing the centering based on the magnitude of the amount of movement or eccentricity. And a step of deciding whether or not to perform, and an eccentricity evaluation method comprising: 2. A demodulating means for reading a servo pattern, which is partially written in a state where the magnetic disk medium is biased in advance, to a demodulation circuit after centering the magnetic disk medium, and the read servo pattern. An eccentricity measurement including an arithmetic means for measuring an amplitude voltage value of a primary rotation component (periodic component) included in a read signal on one round of position information to obtain an amount of movement or eccentricity of the magnetic disk medium by arithmetic operation. A servo pattern writing device comprising: a means for deciding whether to write a normal servo pattern or redo the centering based on the magnitude of the amount of movement or eccentricity. 3. The servo pattern writing apparatus according to claim 2, wherein the eccentricity amount measuring means has a predetermined track pitch t.
The position sensitivity k = track pitch tp × n / Δv is calculated from the change voltage value Δv of the amplitude voltage of the plurality of read position information based on the read information of a plurality of track positions written in the magnetic disk medium at p. Then, the position sensitivity k and the output voltage value V _0p which is ½ of the amplitude voltage value
The servo pattern writing device is characterized in that the moving amount or eccentric amount x = k · V _{0p in} the radial direction of the center position of the magnetic disk medium is calculated from the following. 4. The servo pattern writing apparatus according to claim 2 or 3, wherein the first step of writing the servo pattern on the magnetic disk medium, and the magnetic disk medium on which the servo pattern is written are incorporated into a magnetic disk apparatus. A servo pattern writing device used in at least one of the first and second steps in a method of manufacturing a magnetic disk device including a second step, or the magnetic disk device in a state in which the magnetic disk device is completely assembled. A servo pattern writing device used in a step of writing the servo pattern on a disk medium. 5. A magnetic disk device manufacturing system comprising: a first step of writing a servo pattern on a magnetic disk medium; and a second step of incorporating the magnetic disk medium on which the servo pattern is written into a magnetic disk device. A system for manufacturing a magnetic disk device, wherein the eccentricity amount evaluation method according to claim 1 or the servo pattern writing device according to claim 2 or 3 is used in at least one of the first step and the second step. .