JP2010108557A - Method of positioning magnetic head, and magnetic storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately position a magnetic head. <P>SOLUTION: The yield of servo patterns can be improved by evaluating transfer quality of a plurality of sets of servo patterns (step S11) and by selecting a set of servo patterns ( best servo pattern) used for positioning a magnetic disk for each zone on the basis of the evaluation result (step S12). Consequently, positioning accuracy of a magnetic head can be improved by positioning a magnetic head using the servo patterns. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic head positioning method and a magnetic storage device, and more particularly to a magnetic head positioning method for a magnetic storage medium and a magnetic storage device suitable for carrying out the magnetic head positioning method.

  A magnetic disk device (hard disk device (HDD)) mainly includes a magnetic disk (magnetic storage medium) that magnetically records information and a magnetic head that records or reproduces information on a magnetic disk that is rotationally driven by a spindle motor. And. The magnetic head is provided at the tip of the head stack assembly that rotates within a range of a certain angle.

  On the magnetic disk, position information (servo information) for detecting a relative position between the magnetic head and the track on the magnetic disk is magnetically recorded. The magnetic head positioned using this servo information records information (user data) on the magnetic disk. The servo information is formed as a pattern extending in the radial direction of the medium, and includes, for example, a servo clock pattern, a sector mark (SM), and a tracking pattern area.

  Recording of this servo information on a magnetic disk has been conventionally performed using a device called a servo track writer (STW). However, when STW is used, it takes about 30 minutes / sheet to record servo information on a magnetic disk having a recording capacity of 60 Gbytes, for example. In the future, it is considered that the time required for the servo information recording process will further increase as the track recording density increases.

  On the other hand, recently, as a technique for shortening the servo information recording time, a technique for magnetically transferring servo information to a magnetic disk has been proposed (for example, see Patent Document 1).

  In this magnetic transfer method, in a clean room, servo information is transferred by bringing a transfer master on which irregularities corresponding to servo information are formed and a magnetic disk into close contact with each other. For this reason, if close contact and release are repeated many times, dust (contamination) is caught between the transfer master and the magnetic disk, and there is a case where magnetic servo information is not accurately transferred, and so-called transfer defects may occur. is there. In addition, there may be other causes of defects in magnetic transfer such as pattern defects during transfer master fabrication, signal amplitude reduction due to poor adhesion between the transfer master and the magnetic disk, pattern defects, and variations in the magnetic properties of the media. is there. Therefore, recently, various defect inspection methods have been proposed in order to eliminate transfer defects as much as possible and improve yield (see, for example, Patent Documents 2 to 6).

JP 10-40544 A JP 2001-249080 A JP 2001-176001 A JP 2002-74601 A JP 2001-283432 A JP 2001-167434 A

  However, even if the above method is used, it is difficult to eliminate defective sectors. For this reason, when several defective sectors exist in one track, the entire track cannot be used, and an alternative track is prepared instead of the defective track.

  Recently, with the increase in TPI, the number of cases where alternative tracks are used is increasing. However, when the alternative track list prepared in advance becomes full, the transferred medium itself becomes defective, and the magnetic head has a high accuracy. Positioning cannot be performed.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a magnetic head positioning method capable of positioning a magnetic head with high accuracy. It is another object of the present invention to provide a magnetic storage device capable of recording and reproducing information with a magnetic head with high accuracy.

  The magnetic head positioning method described in this specification includes an evaluation step of evaluating the quality of a plurality of sets of servo patterns provided on a magnetic storage medium, using the detection results of the servo patterns by the magnetic head, and the evaluation results A selection step of selecting a set of servo patterns used for positioning of the magnetic head for each area obtained by dividing the magnetic storage medium in the radial direction. This is a magnetic head positioning method using a set of servo patterns selected in a process.

  According to this, based on the results of evaluating the quality of a plurality of sets of servo patterns, a set of servo patterns used for positioning is selected for each area obtained by dividing the magnetic storage medium in the radial direction, and the selected servos are selected. Since the magnetic head is positioned using a set of patterns, the magnetic head can be positioned using a servo pattern having a good quality (high yield) for each region. As a result, the magnetic head can be positioned with high accuracy.

  The first magnetic storage device described in the present specification has a magnetic head, a magnetic storage medium provided with a plurality of sets of servo patterns used for positioning the magnetic head, and the quality of the servo pattern of the magnetic storage medium. A quality evaluation / selection unit that evaluates and selects a set of servo patterns to be used for positioning the magnetic head for each region obtained by dividing the magnetic storage medium in the radial direction, and a servo selected by the quality evaluation / selection unit And a positioning unit for positioning the magnetic head using a pattern.

  According to this, based on the results of the quality evaluation / selection unit evaluating the quality of multiple sets of servo patterns, a set of servo patterns to be used for positioning is selected for each area obtained by dividing the magnetic storage medium in the radial direction. In addition, since the positioning unit positions the magnetic head using the selected set of servo patterns, the magnetic head can be positioned using a high-quality (high yield) servo pattern for each region. . Thereby, information recording and reproduction by the magnetic head can be performed with high accuracy.

  The second magnetic storage device described in the present specification has a magnetic head, a magnetic storage medium provided with a plurality of sets of servo patterns used for positioning the magnetic head, and the quality of the servo pattern of the magnetic storage medium. An information holding unit for holding information on a set of servo patterns used for positioning the magnetic head for each region obtained by dividing the magnetic storage medium in the radial direction, selected from the evaluation results, and held in the information holding unit And a positioning unit for positioning the magnetic head based on the information.

  According to this, since the positioning unit performs positioning of the magnetic head based on the information of the servo pattern set selected for each of the regions obtained by dividing the magnetic storage medium in the radial direction and held by the information holding unit, In addition, the magnetic head can be positioned by using a servo pattern having a high quality (high yield). Thereby, information recording and reproduction by the magnetic head can be performed with high accuracy.

  The magnetic head positioning method described in this specification has an effect that the magnetic head can be positioned with high accuracy. In addition, the magnetic storage device described in this specification has an effect that information recording and reproduction by a magnetic head can be performed with high accuracy.

  Hereinafter, an embodiment of a magnetic storage device of the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows an internal configuration of a hard disk drive (HDD) 100 as a magnetic storage device according to the present embodiment. As shown in FIG. 1, an HDD 100 includes a box-shaped housing 11, a magnetic disk 20 as a magnetic storage medium housed in a space (housing space) inside the housing 11, a spindle motor 15, a head stack assembly (HSA). ) 16, a voice coil motor (VCM) 17, a head positioning circuit, and a control board (not shown) on which various control LSIs are mounted. The housing 11 is actually composed of a base and an upper lid (top cover), but the upper lid is not shown in FIG. The head stack assembly 16 has a magnetic head 161. The head stack assembly 16 is driven (oscillated) around the support shaft 14 by a voice coil motor 17 provided on the side opposite to the magnetic head 161.

  The magnetic disk 20 has a nonmagnetic substrate made of glass or alumina, and is driven to rotate at a high speed by the spindle motor 15. In the present embodiment, only the front surface of the magnetic disk 20 is a recording surface. However, in the magnetic disk 20, both the front side surface and the back side surface may be recording surfaces. A plurality of magnetic disks 20 may be provided along the rotation axis (along the direction orthogonal to the plane of FIG. 1).

  As schematically shown in FIG. 2A, four sets of servo pattern groups SP1, SP2, SP3, and SP4 are provided on the recording surface of the magnetic disk 20 at equal intervals. Each of these four sets of servo pattern groups SP1 to SP4 has the same number of servo patterns as the number of sectors on the magnetic disk 20, and the angles between the servo patterns are set to equal angles. In the present embodiment, the types of servo patterns (types of phase pattern, area pattern, etc.) are the same. However, the present invention is not limited to this, and different types of servo patterns may be used.

  In the following description, when it is necessary to clarify to which servo pattern group the servo patterns constituting the servo pattern groups SP1 to SP4 belong, the servo pattern group is also applied to a single servo pattern. The same reference numerals SP1 to SP4 are attached.

  In this embodiment, as can be seen from FIG. 2 (b) showing an enlarged part of the servo pattern, an amplitude pattern is adopted as the servo pattern. These servo patterns have a preamble part, an address part, and a burst part as shown in FIG. The address part includes a servo pattern set number, a track number, and a sector number. The servo pattern group number means the numbers “1” to “4” of the servo pattern group sets SP1 to SP4.

  FIG. 3 shows a block diagram of a basic configuration of a positioning control system 50 as a positioning unit for executing positioning of the magnetic head 161. As shown in FIG. 3, the positioning control system 50 includes a feedback controller (FB controller) 21, a VCM 17 to be controlled, calculation blocks 23a, 23b, 23c, and 23d, and samplers 25a and 25b. The sampler 25a includes an A / D converter, and the sampler 25b includes a D / A converter. The positioning control system 50 enables accurate feedback control of the VCM 17 (magnetic head 161) in consideration of the effects of acceleration disturbance, position disturbance, and spindle motor RRO (Repeatable Run Out). The block diagram of FIG. 3 shows the basic configuration of the positioning control system 50. Actually, other configurations (the quality evaluation selection calculation unit 31, the best servo pattern storage unit 33, etc. shown in FIG. 8) are also included. This point will be described later in detail.

  Next, based on the flowcharts of FIGS. 4 to 6, recording (creation) of servo patterns (servo pattern groups SP <b> 1 to SP <b> 4) on the magnetic disk 20, and the magnetic disk 20 on which the servo patterns are recorded are mounted on the HDD 100. Details of the pre-shipment test to be performed later will be described. It should be noted that the pre-shipment test is performed on all HDDs 100 before shipment.

  First, in step S10 of FIG. 4, n sets (four sets in this embodiment) of servo patterns (SP1 to SPn (SP4)) having the required number of sectors are recorded (produced) on the magnetic disk 20 by the magnetic transfer method. ) In FIG. 7A to FIG. 7D, the processing procedure of step S10 is shown in a simplified manner. FIGS. 7A to 7D show a procedure when the magnetic disk 20 is a magnetic disk for horizontal magnetic recording.

  In this magnetic transfer method, first, a transfer master disk (hereinafter simply referred to as “transfer master”) 302 having a concavo-convex pattern corresponding to servo information to be recorded on the magnetic disk 20 as shown in FIG. Prepare. The uneven pattern of the transfer master 302 is drawn by an EB drawing apparatus, and a magnetic layer is formed on the uneven pattern portion.

  Next, as shown in FIG. 7B, an external magnetic field A (magnetic head 303) is brought close to the magnetic disk 20 in which servo information is recorded, and the magnetic layer of the magnetic disk 20 is unidirectionally (A1). Magnetize (initial magnetization).

  Next, as shown in FIG. 7C, a magnetic field B opposite to the initial magnetization is applied from the transfer master 302 side with the transfer master 302 and the magnetic disk 20 in close contact with each other.

  At this time, the portion of the magnetic disk 20 in contact with the transfer master 302 is reversed in magnetization (B1) in the direction opposite to the initial magnetization direction (A1). However, in the portion of the magnetic disk 20 that is not in contact with the transfer master 302, the magnetization in the initial magnetization direction (A1) is maintained as it is as shown in FIG. 7C.

  Next, as shown in FIG. 7D, the servo information (servo pattern) is transferred to the magnetic disk 20 as magnetic information by releasing the close contact between the transfer master 302 and the magnetic disk 20. When the magnetic disk 20 is a magnetic disk for perpendicular magnetic recording, the magnetization direction in FIGS. 7B and 7C may be changed from the horizontal direction to the vertical direction.

  In the present embodiment, since the magnetic transfer method as described above is used, even when a plurality of types of servo pattern groups (SP1 to SP4) are transferred to the magnetic disk 20, the same level as when one type of servo pattern is transferred. Transfer time is sufficient.

  When the transfer of the servo pattern group to the magnetic disk 20 is completed as described above, in the next step S11 (FIG. 4), a subroutine related to evaluation (acquisition) of the transfer quality of the servo pattern is executed. Note that the processing of the subroutine in step S11 is executed by a quality evaluation selection calculation unit 31 (see FIG. 8) as a quality evaluation / selection unit included in the positioning control system 50. However, in the following description, the description of the processing subject is omitted unless particularly required.

  In the subroutine of step S11, first, in step S20 of FIG. 5, a variable k (k = 1 to n (here n = 4)) indicating a set of servo pattern groups is set to 1. Next, in step S22, the magnetic head 161 is on-tracked to the servo pattern group SPk (here, SP1) by the positioning control system 50, and in the next step S24, the transfer quality QEk (here, QE1) is changed to the zone of the magnetic disk 20. Get every.

  The transfer quality QEk is calculated (acquired) by the following equation (1) using a plurality of transfer quality indexes qk (i) (i = 1 to m). Note that ρ (i) is a weighting coefficient.

Here, as the transfer quality index qk (i) (i = 1 to m), indices that can be obtained from the servo pattern information, for example, the following four indices can be used.
qk (1): RPE (repeatable position error) after primary eccentricity correction
qk (2): RPE difference between adjacent tracks qk (3): period component of track fluctuation qk (4): error rate of preamble part, address part and burst part at track center

  When the transfer quality (QE1) of the servo pattern group SP1 is acquired for each zone using the above equation (1), in the next step S26, the variable k is the total number n (here, n = 4). Judge whether there is. At this stage, since k = 1, the determination is negative, and in the next step S28, k is incremented by 1, and then the process returns to step S22.

  After that, by repeating steps S22 to S28, the transfer qualities QE2 to QE4 of the servo pattern groups SP2 to SP4 are obtained for each zone. Then, when the determination in step S26 is affirmed, the process proceeds to step S12 in FIG.

  In the next step S12, the quality evaluation selection calculation unit 31 determines the transfer quality of each servo pattern group acquired in step S11 for each zone, and selects the servo pattern (servo pattern group) with the highest quality in each zone. decide. Then, the servo pattern group having the best quality is set as the “best servo pattern group SPopt” and registered in the best servo pattern storage unit 33 (see FIG. 8) as an information holding unit.

  In FIG. 9, the best servo pattern group selected for each zone is indicated by a bold line. FIG. 9 shows a case where there are three zones on the magnetic disk 20, and the best servo pattern group in the outermost zone 1 is SP1, and the best servo pattern group in the middle zone 2 is A case is shown in which SP3 is the best servo pattern group in the innermost zone 3 is SP4. FIG. 10 is a table showing the relationship between the zone number and the set number of the best servo pattern group selected in the zone. In the table of FIG. 10, unlike the case of FIG. 9, the case where there are three or more zones (r (actual r is around 10 to 20)) is illustrated.

  Next, in step S13 of FIG. 4, an RRO current correction table is created in the positioning control system 50. In this case, the positioning control system 50 (including the delay circuit 36) shown in FIG. 11 moves the magnetic head 161 to the best servo pattern set based on the information of the best servo pattern set SPopt registered in the best servo pattern storage unit 33. Position to. Then, an RRO current correction value is obtained from the amount of misalignment (obtained from servo pattern information or the like) at that time, and an RRO current correction table 35 is created. The positioning control system 50 can improve the positioning accuracy to the servo pattern by performing position control (for example, see FIG. 12) using the RRO current correction table 35.

  Next, in step S14 of FIG. 4, a subroutine (FIG. 6) relating to detection of a defective servo pattern (defective sector) and setting of an alternative pattern is executed for each track in the best servo pattern set. Note that the processing of the subroutine in FIG. 6 is mainly executed by the defect detection / substitution pattern determination unit 37 as a defect detection unit and an alternative unit shown in FIG. However, in the following description, the description of the processing subject is omitted unless particularly required.

  First, in step S30 of FIG. 6, in the best servo pattern set, the positioning control system 50 on-tracks the magnetic head 161 to the first target track for defective sector detection. Note that any track on the magnetic disk 20 may be set as the first target track, but here, for example, the track located on the outermost periphery of the magnetic disk is set as the first target track. To do.

  In the next step S32, the best pattern is detected while the magnetic head 161 is on-tracked on the first target track. Next, in step S34, the defect detection / substitution pattern determination unit 37 determines whether or not there is a defective sector on the target track. The detection of the defective sector is performed based on the defective sector detection index Df (j).

Here, as the bad sector detection index Df (j), for example, the following indices can be used, and when any of these indices exceeds a prescribed value (threshold value) set for each index, Assume that a sector is determined as a bad sector.
Df (1): Signal amplitude and SN of preamble part, address part, burst part, etc.
Df (2): RPE and NRPE obtained by servo evaluation
Df (3): Error rate acquired by data write / read evaluation

  If the determination in step S34 is negative, the process proceeds to step S50. If the determination is positive, the process proceeds to step S36. Here, for example, the following description will be given assuming that the servo pattern indicated by the symbol “BSP” in FIG. 13 is defective (defective sector).

  Next, in step S36, the defect detection / substitution pattern determination unit 37 detects (evaluates) the quality of a servo pattern (another set of servo patterns) adjacent to the defective servo pattern BSP in the same manner as in step S11. Here, for example, the servo pattern adjacent to the servo pattern (SP1) registered as the best servo pattern set has priority. Assuming that the optimum servo pattern set is SP1, if a defective servo pattern BSP occurs in sector # 3 (the number of the sector increases counterclockwise), the priority order is bad sector # 3 ( BSP) is close to the counterclockwise direction and close to the clockwise direction, and the order is SP2 (sector # 3) → SP4 (sector # 2) → SP3 (sector # 3). Therefore, in step S36, the servo pattern SP2 (sector # 3) with the highest priority is evaluated.

  When the servo pattern registered as the best servo pattern set is the servo pattern SP2 and the bad sector is the sector # 3, the priority order of the adjacent servo patterns is close to the counterclockwise direction. SP3 (sector # 3) → SP1 (sector # 3) → SP4 (sector # 3) in the order of closeness to the rotation direction. That is, in general, the priority order is the servo pattern SPs registered as the best servo pattern set closest to the counterclockwise servo pattern → the servo pattern closest to the clockwise direction → second counterclockwise. The closest servo pattern is followed by the second closest servo pattern in the clockwise direction. In this case, when there are 1 to n sets of servo patterns, the servo pattern close to n / 2th counterclockwise is evaluated and the servo pattern closest to n / 2 counterclockwise is evaluated. It should be an evaluation target.

  In the next step S38, the defect detection / substitution pattern determination unit 37 determines whether or not the adjacent servo pattern (SP2 (sector # 3)) is good as a result of step S36. If the determination here is negative (if it is defective), it is determined in step S40 whether there is another set of adjacent servo patterns in the same sector and the previous sector. Here, since the servo pattern SP2 has only been evaluated, the process returns to step S36 to evaluate the next priority servo pattern (SP4 (sector # 2)). When a good servo pattern is found in this way, the determination in step S38 is affirmed and the process proceeds to step S44. On the other hand, if all sets of servo patterns in the same sector and the previous sector are defective in step S40, the determination in step S40 is negative and the process proceeds to step S42. In step S42, the defect detection / alternative pattern determination unit 37 determines that the sector including the servo pattern indicated by the symbol BSP in FIG. 13 is a defective sector, and uses the determination result as a defective sector / alternative pattern as an information holding unit. Register in the storage unit 39.

  In contrast, when the determination in step S38 is affirmative and the process proceeds to step S44, the defect detection / substitution pattern determination unit 37 determines that the servo pattern determined to be good in step S38 and the best servo pattern adjacent on the same track. It is determined whether or not the interval between is less than a predetermined value (reference value). The predetermined value (reference value) in this case means an interval that can secure the time required for servo calculation. More specifically, after a certain servo pattern is detected, the next servo calculation is completed. It means an interval at which pattern detection is not started.

For example, it is assumed that the servo pattern (SP2) is determined to be good with respect to the defective servo pattern BSP shown in FIG. 13 (step S38 in FIG. 6). In this case, operation time D ₁₂ of the servo pattern SP2 (sector # 3) adjacent to the servo pattern SP1 (sector # 2) to determine whether a predetermined operation time D (reference value) or less. Similarly, if it is determined in step S38 in FIG. 6 that the servo patterns SP4 and SP3 are good, the calculation time D ₁₄ between the servo pattern SP1 (sector # 2) and the adjacent servo pattern SP4 (sector # 2). Alternatively, it is determined whether the calculation time D ₁₃ between the servo pattern SP1 (sector # 2) and the adjacent pattern SP3 (sector # 3) is equal to or shorter than a predetermined calculation time D (reference value). In this case, if the calculation time is longer than the predetermined calculation time D, the determination in step S44 may be denied.

  If the determination in step S44 is negative, the process proceeds to step S40.

  On the other hand, if the determination in step S44 is affirmative, in the next step S46, the defect detection / alternative pattern determination unit 37 sets a good servo pattern as an alternative servo pattern, and a defective sector / alternative pattern storage unit. 39.

  Next, in step S50, the defect detection / substitution pattern determination unit 37 determines whether or not all sectors have been completed on the same track. If the determination is negative, the process moves to the next sector in step S51. After that, the process returns to step S34 and the same processing as described above is executed. On the other hand, if all sectors on the same track have been completed, the process proceeds to step S52. Note that the process also proceeds to step S50 when the above-described determination in step S34 is negative. If the determination in step S50 is affirmed, the process proceeds to step S52, and the end determination of all tracks is performed. If the determination is negative, the process moves to the next track in step S53, and then returns to step S30. Then, the same processing as described above is executed for the next track. If the same processing as described above for all tracks is completed and the determination in step S52 is affirmative, the subroutine in FIG. 6 is terminated and the process proceeds to step S15 in FIG.

  Here, FIG. 14 shows an example of a list (table) of alternative servo patterns registered in the defective sector / alternative pattern storage unit 39 when the subroutine of FIG. 6 is completed. According to the list of FIG. 14, the track number of the bad sector in zone 2 is “T-20000”, the sector numbers are “S-50” and “S-130”, and the best servo set in these sectors. It can be seen that the alternative servo patterns SP2 and SP1 are set in place of the pattern (SP3).

  Returning to FIG. 4, in the next step S15, the positioning control system 50 (including the delay circuit 41) creates an RRO target value correction table. In this case, as shown in FIG. 15, based on the information of the best servo pattern group SPopt registered in the best servo pattern storage unit 33 and the information of the alternative servo pattern registered in the defective sector / alternative pattern storage unit 39. Thus, the magnetic head 161 is actually positioned. Then, the correction value of the RRO target value is acquired from the servo pattern information at that time, and the RRO target value correction table 42 is created. The RRO target value correction table is actually written immediately after each sector of the magnetic disk 20.

  As described above, when all the processes in FIG. 4 are completed, the pre-shipment test of the HDD 100 ends.

  Here, after the shipment of the HDD 100, as shown in FIG. 16, the positioning control system 50 is registered in the best servo pattern information registered in the best servo pattern storage unit 33 and in the defective sector / alternative pattern storage unit 39. The positioning control of the magnetic head 161 is executed using the information of the alternative pattern information, the RRO current correction table 35 and the RRO target value correction table 42.

  In the HDD 100, as information (user information) is recorded (written) on the magnetic disk 20, servo patterns not used for control among the servo patterns transferred onto the magnetic disk 20 are gradually erased. (User information is overwritten).

  As described above in detail, according to the present embodiment, the servo pattern group (best servo pattern group SPopt) used for positioning is determined on the magnetic disk 20 based on the result of evaluating the transfer quality of a plurality of servo pattern groups. Since the selection is made for each zone, the yield of servo patterns used for positioning can be improved. Therefore, the magnetic head 161 can be positioned with high accuracy by positioning the magnetic head 161 using the servo pattern selected as described above.

  In this embodiment, after selecting the best servo pattern set, the best servo pattern set is evaluated again to detect a defective servo pattern, and for each defective servo pattern, any servo pattern other than the best servo pattern set is detected. Therefore, even if a defective servo pattern is included in the best servo pattern, the magnetic head 161 can be positioned with high accuracy.

  In the present embodiment, the alternative servo pattern is set so that the interval between adjacent servo patterns used for position control on the same track (narrower interval) is equal to or less than a reference value (a value considering servo calculation). Therefore, an alternative servo pattern that does not hinder positioning control can be selected.

  In the above embodiment, the case where the evaluation of the transfer quality of the servo pattern group and the selection of the best servo pattern set are performed for each zone has been described. However, the present invention is not limited to this. For example, the transfer quality evaluation and the best servo pattern set may be selected for each track, or the transfer quality may be evaluated and the best servo pattern set may be selected for every several tracks.

  In the above embodiment, the case where the RRO target value correction table is created in the pre-shipment test (step S15) has been described. However, the present invention is not limited to this. It may be created when the power is turned on for the first time.

  In the above embodiment, the case where the magnetic transfer type servo track writer is used has been described. However, the present invention is not limited to this, and other servo track writers such as a push pin type, a stack STW type, and a rewrite STW type are used. Even when a plurality of sets of servo patterns are produced using the copy STW method, it is possible to perform the same positioning control as in the above embodiment.

  In the above embodiment, the quality evaluation selection calculation unit 31 included in the positioning control system 50 is used to determine the best servo pattern set SPopt, and the defect detection / substitution pattern determination unit 37 included in the positioning control system 50 is determined. It was decided to determine an alternative servo pattern. However, the present invention is not limited to this, and as shown in FIG. 17, the HDD 100 is connected to an external test apparatus 200 (a quality evaluation selection calculator 231 having the same function as the quality evaluation selection calculator 31, a defect detection / substitution). It may be connected to a defect detection / substitution pattern determination unit 237 having the same function as the pattern determination unit 37), and the same processing as in the above embodiment may be executed. In this case, the positioning control system 50 of the HDD 100 only needs to have at least a configuration that can use the information acquired by the test apparatus 200. Therefore, the configuration shown in FIG. 16 (the best servo pattern storage unit as an information holding unit) 33 and the configuration including the defective sector / alternative pattern storage unit 39). Even if such a configuration is adopted, the same effect as the above embodiment can be obtained, and it is not necessary to provide a configuration in the HDD 100 that is hardly used after completion of the pre-shipment test. The cost of the apparatus can be reduced.

  In the above-described embodiment, it is assumed that the pre-shipment test is executed for all the HDDs 100 before the shipment, but the present invention is not limited to this. For example, one or a plurality of HDDs on which the same lot of magnetic disks are mounted may be extracted, and the pre-shipment test may be performed only on the extracted HDDs. In this case, the results of tests performed on one or a plurality of units can be used in HDDs equipped with magnetic disks of the same lot. Even in this case, a pattern defect at the time of manufacturing the transfer master, a decrease in signal amplitude due to poor adhesion between the transfer master and the magnetic disk, a pattern defect, etc., occur almost uniformly with the same lot of magnetic disks. It is possible to eliminate the cause of the defective soldering, and it is possible to position the magnetic head with higher accuracy than before.

  The above-described embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

1 is a plan view schematically showing a configuration of an HDD according to an embodiment. FIG. 2A is a diagram schematically showing a plurality of sets of servo patterns recorded on the magnetic disk, and FIG. 2B is a diagram showing a specific configuration of the servo patterns. It is a figure which shows a positioning control system. It is a flowchart which shows the process in the recording of the servo pattern to a magnetic disc, and a pre-shipment test. It is a flowchart which shows the subroutine of step S11. It is a flowchart which shows the subroutine of step S14. It is a figure which shows roughly the process of step S10 of FIG. It is a figure which shows the control system of step S11 of FIG. It is a figure which shows an example of the optimal servo pattern selected by step S12 of FIG. It is a table | surface which shows the optimal servo pattern selected by step S12 of FIG. 4 for every zone number. It is a figure which shows the control system of step S13 of FIG. It is a figure which shows the control system of step S14 of FIG. It is a figure for demonstrating the process of FIG. It is a table | surface which shows the alternative servo pattern set by the process of FIG. It is a figure which shows the control system of step S15 of FIG. It is a figure which shows the positioning control system used for positioning of a magnetic head after shipment. It is a figure which shows the test apparatus with which the HDD which concerns on a modification, and the said HDD are connected in the test before shipment.

Explanation of symbols

20 Magnetic disk (magnetic storage medium)
31 Quality Evaluation Selection Calculation Unit (Quality Evaluation / Selection Unit)
33 Best servo pattern storage unit (part of information storage unit)
37 Defect detection / substitution pattern determination section (defect detection section, substitution section)
39 Bad sector / alternative pattern storage unit (part of information storage unit)
50 Positioning control system (positioning part)
100 HDD (magnetic storage device)
161 Magnetic head BSP Bad servo pattern SP1 to SP4 Servo pattern group (servo pattern)

Claims (9)

An evaluation step of evaluating the quality of a plurality of sets of servo patterns provided on the magnetic storage medium using the detection result of the servo patterns by the magnetic head;
A selection step of selecting a set of servo patterns used for positioning the magnetic head for each region obtained by dividing the magnetic storage medium in the radial direction from the evaluation result,
The magnetic head positioning method uses a set of servo patterns selected in the selection step for positioning the magnetic head. 2. The magnetic head positioning method according to claim 1, wherein, in the selection step, the servo pattern set is selected for each track or zone of the magnetic storage medium. After the selection step, the failure detection step of re-evaluating the selected set of servo patterns and detecting a defective servo pattern;
An alternative step of setting any one of the servo pattern sets not selected in the selection step as an alternative servo pattern for each of the defective servo patterns;
3. The magnetic head positioning method according to claim 1, wherein the substitute servo pattern is used for positioning the magnetic head instead of the defective servo pattern. 4. The substitute servo pattern is determined in the substitute step so that an interval between servo patterns used for positioning of the adjacent magnetic heads on the same track is equal to or less than a reference value. The magnetic head positioning method according to claim 1. A magnetic head;
A magnetic storage medium provided with a plurality of sets of servo patterns used for positioning the magnetic head;
A quality evaluation / selection unit that evaluates the quality of the servo pattern of the magnetic storage medium and selects a set of servo patterns used for positioning the magnetic head for each area obtained by dividing the magnetic storage medium in the radial direction;
A magnetic storage device comprising: a positioning unit that positions the magnetic head using a set of servo patterns selected by the quality evaluation / selection unit. 6. The magnetic storage device according to claim 5, wherein the quality evaluation / selection unit selects the set of servo patterns for each track or each zone of the magnetic storage medium. After the selection by the quality evaluation / selection unit, the defect detection unit that evaluates the set of the selected servo patterns and detects a defective servo pattern;
For each detected defective servo pattern, an alternative unit that sets any one of a set of servo patterns not selected by the quality evaluation / selection unit as an alternative servo pattern,
7. The magnetic storage device according to claim 5, wherein the positioning unit positions the magnetic head by exchanging the defective servo pattern and the alternative servo pattern. The substitute servo pattern is determined by the substitute unit so that an interval between servo patterns used for positioning of the adjacent magnetic heads on the same track is equal to or less than a reference value. The magnetic storage device according to any one of the above. A magnetic head;
A magnetic storage medium provided with a plurality of sets of servo patterns used for positioning the magnetic head;
Information holding for holding information on a set of servo patterns used for positioning the magnetic head for each region obtained by dividing the magnetic storage medium in the radial direction, which is selected from the result of evaluating the quality of the servo pattern on the magnetic storage medium And
A magnetic storage device comprising: a positioning unit that positions the magnetic head based on information held in the information holding unit.

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