Magnetic disk device and head change processing method

Abstract

The embodiment provides a magnetic disk device and a head change processing method capable of improving data format efficiency. The magnetic disk device according to the embodiment includes: a first disk including a plurality of first servo wedges having a first servo pattern in a first partition and a second servo pattern in a second partition; a second disk including a plurality of second servo wedges having the first servo pattern and the second servo pattern and having a second center position shifted from a first center position of the first disk; a first head for reading and writing to the first disk; a second head for reading and writing to the second disk; and a controller for calculating an estimated position where the second head is estimated to be arranged on the second disk based on first relative position information associated with the relative positions of the first head and the second head in the radial direction when switching from the first head to the second head.

Description

[0001] The present application claims priority based on Japanese Patent Application No. 2021-450 (filing date: January 5, 2021) as a basic application. The present application incorporates the entire contents of the basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to a magnetic disk device and a head change processing method. Background Art

[0003] A magnetic disk device may include a plurality of disks that are relatively eccentric (hereinafter sometimes referred to as relative eccentricity) due to the displacement of a subsequent disk (hereinafter sometimes referred to as subsequent disk shift) etc., and a plurality of heads corresponding to the plurality of disks. When the magnetic disk device switches to another head (head change) different from the predetermined head while a predetermined cylinder (predetermined track) is being read by a predetermined head among the plurality of heads to read the cylinder (track), a cylinder (track) different from the predetermined cylinder (track) may be read.

[0004] In addition, a magnetic disk device having servo data divided in the radial direction (hereinafter sometimes referred to as a zone servo type magnetic disk device) has been developed. When a zone servo type magnetic disk device reads a predetermined cylinder by changing the head during the period when a predetermined head among a plurality of heads reads the cylinder, there is a possibility that the position of the head cannot be correctly demodulated because the servo data of a cylinder different from the cylinder is read. Summary of the invention

[0005] Embodiments of the present invention provide a magnetic disk device and a header change processing method capable of improving data format efficiency.

[0006] The magnetic disk device according to the present embodiment includes: a first disk divided into a first partition and a second partition by a boundary in a radial direction, and including a plurality of first servo wedges having a first servo pattern arranged in the first partition and a second servo pattern arranged in the second partition; a second disk divided into the first partition and the second partition by the boundary in the radial direction, and including a plurality of second servo wedges having the first servo pattern and the second servo pattern, and having a second center position shifted from a first center position of the first disk; a first head that writes data to the first disk and reads data from the first disk; a second head that writes data to the second disk and reads data from the second disk; and a controller that calculates an estimated position where the second head is estimated to be arranged on the second disk based on first relative position information associated with the relative positions of the first head and the second head in the radial direction when switching the first head to the second head. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram showing an example of the structure of the magnetic disk device 1 according to the embodiment.

[0008] Figure 2 This is a plan view showing an example of the arrangement of the head with respect to the disk.

[0009] Figure 3 It is a plan view showing an example of the arrangement of the servo wedges of the disk according to the embodiment.

[0010] Figure 4 It is a plan view showing an example of the arrangement of the servo wedges of the disk according to the embodiment.

[0011] Figure 5 This is a schematic diagram showing an example of a servo sector.

[0012] Figure 6 FIG. 1 is a plan view showing an example of the arrangement of servo tracks on a non-eccentric disk.

[0013] Figure 7 FIG. 1 is a plan view showing an example of the arrangement of the servo tracks and the virtual servo tracks with respect to the eccentric disk.

[0014] Figure 8 FIG. 1 is a plan view showing an example of the arrangement of the servo tracks and the virtual servo tracks with respect to the eccentric disk.

[0015] Fig. 9 This is a block diagram showing an example of a servo control system according to the embodiment.

[0016] Fig.10 This is a top view showing an example of virtual circle control.

[0017] Fig.11 This is a schematic diagram showing an example of virtual circle control.

[0018] Fig.12 It is a plan view showing an example of eccentricity of the disk with respect to the spindle according to the present embodiment.

[0019] Fig.13 This is a schematic diagram showing an example of head change of a plurality of different heads corresponding to a plurality of different disks.

[0020] Fig.14 This is a schematic diagram showing an example of the timing for calculating the relative position between heads when changing the head.

[0021] Fig.15 This is a schematic diagram showing an example of a servo gate that does not correct the timing when the head is changed.

[0022] Fig.16This is a schematic diagram showing an example of a servo gate in which the timing is corrected when the head is changed.

[0023] Fig.17 This is a schematic diagram showing an example of a servo gate in which the timing is corrected when the head is changed.

[0024] Fig.18 This is a schematic diagram showing an example of a table including COSTABLE and SINTABLE.

[0025] Fig.19 1 is a schematic diagram showing an example of a table showing eccentricity compensation current values ​​corresponding to a predetermined head HD.

[0026] Fig. 20 This is a schematic diagram showing an example of a table of DFT coefficients corresponding to the relative positions between two heads HD before and after a head change.

[0027] Fig.21 This is a flowchart showing an example of a header change processing method according to an embodiment.

[0028] Fig. 22 This is a flowchart showing an example of a method for calculating the relative position between heads according to an embodiment.

[0029] Fig.23 This is a flowchart showing an example of a method for calculating the relative positions between AC part heads involved in an implementation method.

[0030] Fig.24 This is a flowchart showing an example of a correction processing method of a servo zone according to an embodiment.

[0031] Fig.25 This is a flowchart showing an example of an interrupt processing method for each sampling according to the present embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, the embodiments will be described with reference to the drawings. Note that the drawings are examples and do not limit the scope of the invention.

[0033] (Implementation Method)

[0034] Figure 1 It is a schematic diagram showing an example of the structure of the magnetic disk device 1 according to the embodiment.

[0035] The magnetic disk device 1 includes a housing HS, a head disk assembly (HDA) 10, a driver IC 20, a head amplifier integrated circuit (hereinafter referred to as a head amplifier IC or a preamplifier) ​​30, a volatile memory 70, a nonvolatile memory 80, a buffer memory (cache) 90, and a system controller 130 which is an integrated circuit of one chip. In addition, the magnetic disk device 1 is connected to a host system (hereinafter referred to as a host) 100. Figure 1 Schematic diagram of the cross section of the frame HS and the HDA 10 is shown in FIG.

[0036] The frame HS has a bottom wall HSB. Figure 1 Although the frame HS is shown to have only the bottom wall HSB, in reality, the frame HS has, for example, the bottom wall HSB, side walls erected along the periphery of the bottom wall HSB, and a cover that closes an opening of a base body composed of the bottom wall HSB and the side walls.

[0037] The HDA 10 includes a magnetic disk (hereinafter referred to as a disk) DK, a head HD, a spindle motor (hereinafter referred to as SPM) 13 for rotating a spindle 12, an arm AM, an actuator block BK, a voice coil motor (hereinafter referred to as VCM) 14, and a microactuator (hereinafter referred to as MA) 15 on which the head HD is mounted. The arm AM, the actuator block BK, the VCM 14, and the MA 15 constitute an actuator ACT. The actuator ACT controls the movement of the head HD mounted on the MA 15 to a predetermined position of the disk DK by the drive of the VCM 14. In addition, the HDA 10 may not have the MA 15. In the case where the HDA 10 does not have the MA 15, the head HD may be mounted on the arm AM. In the case where the HDA 10 does not have the MA 15, the arm AM, the actuator block BK, and the VCM 14 constitute an actuator ACT. In this case, the actuator ACT controls the movement of the head HD mounted on the arm AM to a predetermined position of the disk DK by the drive of the VCM 14.

[0038] SPM13 is mounted on the bottom wall HSB. A spindle 12 is mounted on the center portion of SPM13. The disk DK has a plurality of disks DK. The disk DK is mounted on the spindle 12 and is rotated by the drive of SPM13. The disk DK has a surface (upper surface) FS and a back surface (lower surface) RS on the opposite side of the surface (upper surface) FS. Hereinafter, the surface (upper surface) FS and / or the back surface (lower surface) RS may also be referred to as disk DK. Figure 1In the example shown, disk DK has disks DK0 and DK1. Disks DK0 and DK1 are mounted on the spindle 12. Disk DK1 is, for example, arranged between disk DK0 and bottom wall HSB. Disk DK0 has an upper surface FS0 and a lower surface RS0 on the opposite side of upper surface FS0. Disk DK1 has an upper surface FS1 and a lower surface RS1 on the opposite side of upper surface FS1. In addition, disk DK may also have more than three disks. Hereinafter, the direction along the circumference of disk DK will be referred to as the circumferential direction, and the direction orthogonal to the circumferential direction in the upper surface FS and the lower surface RS of disk DK will be referred to as the radial direction. The radial direction is equivalent to the direction toward the inner circumference and the outer circumference in the upper surface FS and the lower surface RS of disk DK.

[0039] The head HD has a plurality of heads HD. The head HD faces the disk DK. The head HD has a write head WH for writing data to the disk DK and a read head RH for reading the data written to the disk DK. Hereinafter, "writing data to the disk DK" is sometimes referred to as "writing" or "writing process", and "reading data from the disk DK" is sometimes referred to as "reading" or "reading process". In addition, "recording data in a predetermined recording area", "reading data from a predetermined recording area", "arranging the head HD at a predetermined position on the disk DK", "writing data to a predetermined area of ​​the disk DK", "reading data from a predetermined area of ​​the disk DK", "connecting to a predetermined area in a manner capable of communicating", etc. are sometimes referred to as "access". Figure 1 In the example shown, the head HD includes heads HD0, HD1, HD2, and HD3. For example, the head HD0 faces the upper surface FS0 of the disk DK0. The head HD0 includes a write head WH0 that writes data to the upper surface FS0, and a read head RH0 that reads the data written to the upper surface FS0. For example, the head HD1 faces the lower surface RS0 of the disk DK0. The head HD1 includes a write head WH1 that writes data to the lower surface RS0, and a read head RH1 that reads the data written to the lower surface RS0. For example, the head HD2 faces the upper surface FS1 of the disk DK1. The head HD2 includes a write head WH2 that writes data to the upper surface FS1, and a read head RH2 that reads the data written to the upper surface FS1. For example, the head HD3 faces the lower surface RS1 of the disk DK1. The head HD3 includes a write head WH3 that writes data to the lower surface RS1, and a read head RH3 that reads the data written to the lower surface RS1. In addition, the head HD may have 3 or less heads, or may have 5 or more heads.

[0040] The actuator block BK is rotatably mounted on a bearing BR provided upright on the bottom wall HSB.

[0041] The arm AM includes a plurality of arms AM. The other end of the arm AM on the opposite side to the front end on the disk DK side is connected to the actuator block BK. In addition, the arm AM may also be equipped with a suspension. Figure 1 In the example shown, the arm AM includes arms AM0, AM1, AM2, and AM3. Arm AM0 is, for example, disposed on the upper surface FS0 side of the disk DK0. In other words, arm AM0 is configured to face the upper surface FS0. The other end of arm AM0 on the side opposite to the front end portion on the disk DK0 side is connected to the actuator block BK. Arm AM1 is, for example, disposed on the lower surface RS0 side of the disk DK0. In other words, arm AM1 is configured to face the lower surface RS0. The other end of arm AM1 on the side opposite to the front end portion on the disk DK0 side is connected to the actuator block BK. Arm AM2 is, for example, disposed on the upper surface FS1 side of the disk DK1. In other words, arm AM2 is configured to face the upper surface FS1. The other end of arm AM2 on the side opposite to the front end portion on the disk DK1 side is connected to the actuator block BK. Arm AM3 is, for example, disposed on the lower surface FS1 side of the disk DK1. In other words, arm AM3 is configured to face the lower surface RS1. The other end of the arm AM3 on the opposite side to the front end on the disk DK1 side is connected to the actuator block BK. In addition, the arm AM may have less than 3 arms or more than 5 arms. In addition, when the HDA10 does not have the MA15, the arm AM may also be equipped with a head HD at the front end. For example, the arm AM0 may be equipped with a head HD0 at the front end, the arm AM1 may be equipped with a head HD1 at the front end, the arm AM2 may be equipped with a head HD2 at the front end, and the arm AM3 may be equipped with a head HD3 at the front end.

[0042] The VCM 14 is connected to the actuator block BK on the side opposite to the arm AM.

[0043] MA15 includes a plurality of MA15. MA15 is installed at the front end of arm AM. MA15 can be driven independently of VCM14. MA15 is installed, for example, at the suspension of arm AM. MA15 is equipped with a head HD at the front end opposite to the end connected to arm AM. MA15 controls the movement of head HD in the radial direction finely. For example, MA15 controls the movement of head HD in the radial direction finer than the movement of head HD in the radial direction achieved by VCM14. Figure 1In the example shown, MA15 includes MA150, MA151, MA152, and MA153. For example, the other end of MA150 is connected to the front end of arm AM0, and head HD0 is mounted on the front end opposite to the other end. For example, the other end of MA151 is connected to the front end of arm AM1, and head HD1 is mounted on the front end opposite to the other end. For example, the other end of MA152 is connected to the front end of arm AM2, and head HD2 is mounted on the front end opposite to the other end. For example, the other end of MA153 is connected to the front end of arm AM3, and head HD3 is mounted on the front end opposite to the other end. In addition, MA15 may have less than 3 MAs or more than 5 MAs according to the number of heads HD.

[0044] The actuator ACT is mounted on the bearing BR in a freely rotatable manner (or freely rotating manner). The actuator ACT is composed of an arm AM, an actuator block BK, a VCM14, and an MA15. The actuator ACT drives the VCM14 around the bearing BR and finely drives the MA15, thereby positioning the head HD mounted on the MA15 at a predetermined position on the disk DK. In addition, when the HDA10 does not have the MA15, the actuator ACT is composed of an arm AM, an actuator block BK, and a VCM14. In this case, the actuator ACT drives the VCM14 around the bearing BR to position the head HD mounted on the arm AM at a predetermined position on the disk DK. Figure 1 In the example shown, the actuator ACT is composed of MA150 to 153, arms AM0 to AM3, actuator blocks BK, and VCM14. The actuator ACT drives the VCM14 by rotating the shaft around the bearing BR, and drives MA150 to 153 finely, respectively, so that the head HD0 mounted on the MA150 is positioned at a predetermined position on the upper surface FS0, the head HD1 mounted on the MA151 is positioned at a predetermined position on the lower surface RS0, the head HD2 mounted on the MA152 is positioned at a predetermined position on the upper surface FS1, and the head HD3 mounted on the MA153 is positioned at a predetermined position on the lower surface RS0. In addition, when HDA10 does not have MA15, the actuator ACT drives VCM141 through the rotating axis around the bearing BR, thereby positioning the head HD0 mounted on the arm AM0 at a predetermined position on the upper surface FS0, positioning the head HD1 mounted on the arm AM1 at a predetermined position on the lower surface RS0, positioning the head HD2 mounted on the arm AM2 at a predetermined position on the upper surface FS1, and positioning the head HD3 mounted on the arm AM3 at a predetermined position on the lower surface RS1.

[0045] Figure 2 FIG. 1 is a top view showing an example of the configuration of the head HD relative to the disk DK. Figure 2, a first direction X, a second direction Y, and a third direction Z are shown. In one example, the first direction X, the second direction Y, and the third direction Z are orthogonal to each other, but may also intersect at an angle other than 90 degrees. Figure 2 In the embodiment, the upper surface FS (FS0, FS1) and the lower surface RS (RS0, RS1) of the disk DK (DK0, DK1) extend in the X-Y plane. Figure 2 As shown in FIG. 1 , the direction toward the outermost periphery OCP (OCP0, OCP1) of the disk DK in the radial direction is sometimes referred to as the outer direction (outer side), and the direction toward the innermost periphery ICP (ICP0, ICP1) of the disk DK, that is, the direction opposite to the outer direction, is sometimes referred to as the inner direction (inner side). Figure 2 As shown in FIG. 1 , the right-hand (clockwise) direction relative to the disk DK in the circumferential direction is sometimes referred to as the right direction, and the direction opposite to the right-hand direction (counterclockwise) is sometimes referred to as the left direction. The direction in which the disk DK rotates in the circumferential direction is sometimes referred to as the rotation direction. Figure 2 In the example shown, the direction of rotation is indicated by the left direction (counterclockwise), but it may also be the opposite direction (right direction or clockwise). Figure 2 The center (hereinafter sometimes referred to as the disk center) DKC (DKC0, DKC1) of the disk DK (DK0, DK1) and the (rotation) center (hereinafter sometimes referred to as the rotation center) SPC of the spindle 12 are shown. The disk center DKC (DKC0, DKC1) and the rotation center SPC extend, for example, along the third direction Z. Figure 2 In the example, the disk center DKC (DKC0, DKC1) is consistent with the rotation center SPC. The terms "same", "identical", "consistent" and "equivalent" include the meaning of being completely the same, and also include the meaning of being different to the extent that they can be considered to be substantially the same. In addition, the disk center DKC and the rotation center SPC may not be consistent. In other words, the disk center DKC and the rotation center SPC may be offset. Figure 2 In the embodiment, a gap (clearance) GP0 is generated between the innermost circumference ICP (ICP0, ICP1) of the disk DK (DK0, DK1) and the spindle 12. Alternatively, the gap GP0 may not be generated between the innermost circumference IPC (ICP0, ICP1) of the disk DK (DK0, DK1) and the spindle 12.

[0046] The upper surface FS and the lower surface RS of the disk DK are allocated with user data areas FSa and RSa that can be used by the user and system areas FSb and RSb for writing information required for system management (hereinafter sometimes referred to as system information) for the areas where data can be written. Hereinafter, the predetermined position in the radial direction of the upper surface FS and the lower surface RS of the disk DK is sometimes referred to as the radial position, and the predetermined position in the circumferential direction of the upper surface FS and the lower surface RS of the disk DK is sometimes referred to as the circumferential position. The radial position and the circumferential position are sometimes referred to as the position together. For example, the radial position is equivalent to the position in the radial direction of the track or sector (data sector), and the circumferential position is equivalent to the position in the circumferential direction of the sector in the predetermined track. For example, the position is equivalent to the position of the sector (data sector) in the upper surface FS and the lower surface RS of the disk DK. The position of the sector (data sector) can be represented by at least one of the cylinder (track) number including the predetermined sector, the head number of the head HD that accesses the predetermined sector, the sector number of the predetermined sector, the radial position of the predetermined sector in the upper surface FS and the lower surface RS of the disk DK, and the disk angle of the predetermined sector. For example, the position of the sector is represented by a combination of two of the cylinder (track) number including the predetermined sector, the head number of the head HD that accesses the predetermined sector, the sector number of the predetermined sector, the radial position of the predetermined sector in the disk DK, and the disk angle of the predetermined sector.

[0047] The upper surface FS and the lower surface RS of the disk DK are divided into a plurality of areas (hereinafter sometimes referred to as partitions or partition areas) according to a predetermined range in the radial direction. A partition may include a plurality of tracks arranged in the radial direction. A track may include a plurality of sectors arranged in the circumferential direction. In addition, the "track" is used to mean one of the plurality of areas obtained by dividing the upper surface FS and the lower surface RS of the disk DK in the radial direction according to a predetermined range, the path of the head HD corresponding to the predetermined radial position of the upper surface FS and the lower surface RS of the disk DK, data extending in the circumferential direction in the predetermined radial direction of the upper surface FS and the lower surface RS of the disk DK, one-circle data written in the predetermined track of the upper surface FS and the lower surface RS of the disk DK, data written in the predetermined track of the upper surface FS and the lower surface RS of the disk DK, and other various meanings. "Sector" is used to refer to one of a plurality of areas obtained by dividing the predetermined tracks of the upper surface FS and the lower surface RS of the disk DK in the circumferential direction, data written at a predetermined circumferential position at a predetermined radial position of the upper surface FS and the lower surface RS of the disk DK, data written in a predetermined sector of the upper surface FS and the lower surface RS of the disk DK, and other various meanings. The "width in the radial direction of the track" is sometimes referred to as the "track width". In addition, the "width in the radial direction of the sector" is sometimes referred to as the "sector width". In the following, the path passing through the center position of the track width at each circumferential position of the predetermined track is sometimes referred to as the track center.

[0048] exist Figure 2 In the example shown, the upper surface FS0 of the disk DK0 is allocated with a user data area FSa0 and a system area FSb0. The lower surface RS0 of the disk DK0 is allocated with a user data area RSa0 and a system area RSb0. The upper surface FS1 of the disk DK1 is allocated with a user data area FSa1 and a system area FSb01. The lower surface RS1 of the disk DK1 is allocated with a user data area RSa1 and a system area RSb1.

[0049] When seeking, for example, the head HD is rotated around the bearing BR by the actuator ACT, thereby sliding in the horizontal plane of the disk DK. Figure 2 In the example shown, head HD0, for example, rotates around bearing BR via actuator ACT during seek, thereby sliding on upper surface FS0 of disk DK0. Head HD1, for example, rotates around bearing BR via actuator ACT during seek, thereby sliding on lower surface RS0 of disk DK0. Head HD2, for example, rotates around bearing BR via actuator ACT during seek, thereby sliding on upper surface FS1 of disk DK1. Head HD3, for example, rotates around bearing BR via actuator ACT during seek, thereby sliding on lower surface RS1 of disk DK1.

[0050] Figure 3 FIG. 2 is a top view showing an example of the arrangement of the servo wedge SvWd of the disk DK0 according to the present embodiment. Figure 3 In the embodiment, the disk center DKC0 of the disk DK0 coincides with the rotation center SPC. Figure 3 In the embodiment, a gap GP0 is generated between the innermost circumference ICP0 of the disk DK0 and the spindle 12. Alternatively, the gap GP0 may not be generated between the innermost circumference ICP0 of the disk DK0 and the spindle 12.

[0051] The user data areas FSa and RSa of the upper surface FS and the lower surface RS of the disk DK are divided into a plurality of partitions (hereinafter sometimes referred to as servo partitions) by respective boundaries BD in the radial direction. The upper surface FS and the lower surface RS of the disk DK have a plurality of servo wedges SvWd. In the upper surface FS and the lower surface RS of the disk DK, user data can be written in the areas other than the plurality of servo wedges SvWd. In the upper surface FS and the lower surface RS of the disk DK, the plurality of servo wedges SvWd are arranged at intervals in the circumferential direction. The servo wedge SvWd is composed of a plurality of servo areas SvR arranged in the radial direction of the upper surface FS and the lower surface RS of the disk DK. For example, the servo wedge SvWd is composed of a plurality of servo areas SvR arranged in a staggered manner in the radial direction of the disk DK. The servo wedge SvWd is arranged with the servo areas SvR arranged in each partition. The servo wedge SvWd is arranged with the plurality of servo areas SvR overlapping in the radial direction. For example, in the servo wedge SvWd, a plurality of servo areas SvR are arranged in an overlapping manner near the boundary BD of the partition. Hereinafter, the area in the radial direction where the plurality of servo areas SvR are arranged in an overlapping manner in the servo wedge SvWd is sometimes referred to as an overlapping area OvR. The overlapping area OvR corresponds to the area where the plurality of servo areas SvR are arranged in the circumferential direction in the servo wedge SvWd. For example, the overlapping area OvR may also include the boundary BD. In addition, the overlapping area OvR may not include the boundary BD. Hereinafter, one servo area SvR in a predetermined track is sometimes referred to as a "servo sector". In addition, a "servo area" is sometimes referred to as a "servo sector". A servo sector includes servo data. A data pattern constituting servo data is sometimes referred to as a servo pattern. In addition, a "servo area in which servo data is written" and a "servo sector in which servo data is written" are sometimes referred to as "servo data", "servo sector", "servo pattern" or "servo area".

[0052] exist Figure 3 In the example shown, the user data areas FSa0 and RSa0 of the upper surface FS0 and the lower surface RS0 of the disk DK0 are divided into a servo partition SvZn00 and a servo partition SvZn01 by a boundary BD0 in the radial direction. The servo partition SvZn00 is arranged at a position on the outside of the servo partition SvZn01. In other words, the servo partition SvZn01 is arranged at a position on the inside of the servo partition SvZn00. The upper surface FS0 and the lower surface RS0 of the disk DK0 have servo wedges SvWd00, SvWd01, SvWd02, and SvWd03. The servo wedges SvWd00 to SvWd03 are arranged at intervals in the circumferential direction in the upper surface FS0 and the lower surface RS0 of the disk DK0.

[0053] The servo wedge SvWd00 includes a servo area SvRI00 and a servo area SvRO00. The servo area SvRI00 is arranged at a position inside the servo area SvRO00. The servo area SvRI00 is arranged in the servo partition SvZn01. The servo area SvRI00 is arranged from the innermost circumference ICP0 side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly outside the boundary BD0. The servo area SvRO00 is arranged at a position outside the servo area SvRI00. The servo area SvRO00 is arranged in the servo partition SvZn00. The servo area SvRO00 is arranged from the outermost circumference OCP (OCP0) side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly inside the boundary BD0. The servo areas SvRI00 and SvRO00 are arranged in the circumferential direction in the overlap area OvR0.

[0054] The servo wedge SvWd01 includes a servo area SvRI01 and a servo area SvRO01. The servo area SvRI01 is arranged at a position inside the servo area SvRO01. The servo area SvRI01 is arranged in the servo partition SvZn01. The servo area SvRI01 is arranged from the innermost circumference ICP0 side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly outside the boundary BD0. The servo area SvRO01 is arranged at a position outside the servo area SvRI01. The servo area SvRO01 is arranged in the servo partition SvZn00. The servo area SvRO01 is arranged from the outermost circumference OCP (OCP0) side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly inside the boundary BD0. The servo areas SvRI01 and SvRO01 are arranged in the circumferential direction in the overlapping area OvR0.

[0055] The servo wedge SvWd02 includes a servo area SvRI02 and a servo area SvRO02. The servo area SvRI02 is arranged at a position inside the servo area SvRO02. The servo area SvRI02 is arranged in the servo partition SvZn01. The servo area SvRI02 is arranged from the innermost circumference ICP0 side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly outside the boundary BD0. The servo area SvRO02 is arranged at a position outside the servo area SvRI02. The servo area SvRO02 is arranged in the servo partition SvZn00. The servo area SvRO02 is arranged from the outermost circumference OCP (OCP0) side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly inside the boundary BD0. The servo areas SvRI02 and SvRO02 are arranged in the circumferential direction in the overlapping area OvR0.

[0056] The servo wedge SvWd03 includes a servo area SvRI03 and a servo area SvRO03. The servo area SvRI03 is arranged at a position inside the servo area SvRO03. The servo area SvRI03 is arranged in the servo partition SvZn01. The servo area SvRI03 is arranged from the innermost circumference ICP0 side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly outside the boundary BD0. The servo area SvRO03 is arranged at a position outside the servo area SvRI03. The servo area SvRO03 is arranged in the servo partition SvZn00. The servo area SvRO03 is arranged from the outermost circumference OCP (OCP0) side of the upper surface FS0 and the lower surface RS0 across the boundary BD0 to a position slightly inside the boundary BD0. The servo areas SvRI03 and SvRO03 are arranged in the circumferential direction in the overlapping area OvR0.

[0057] Figure 4 FIG. 2 is a plan view showing an example of the arrangement of the servo wedge SvWd of the disk DK1 according to the present embodiment. Figure 4 In the embodiment, the disk center DKC1 of the disk DK1 coincides with the rotation center SPC. Figure 4 In the embodiment, a gap GP0 is generated between the innermost circumference ICP1 of the disk DK1 and the spindle 12. Alternatively, the gap GP0 may not be generated between the innermost circumference ICP1 of the disk DK0 and the spindle 12.

[0058] exist Figure 4 In the example shown, the user data areas FSa1 and RSa1 of the upper surface FS1 and the lower surface RS1 of the disk DK1 are divided into a servo partition SvZn10 and a servo partition SvZn11 by a boundary BD1 in the radial direction. The servo partition SvZn10 is arranged at a position closer to the outside than the servo partition SvZn11. In other words, the servo partition SvZn11 is arranged at a position closer to the inside than the servo partition SvZn10. The upper surface FS1 and the lower surface RS1 of the disk DK1 have servo wedges SvWd10, SvWd11, SvWd12, and SvWd13. The servo wedges SvWd10 to SvWd13 are arranged at intervals in the circumferential direction in the upper surface FS1 and the lower surface RS1 of the disk DK1.

[0059] The servo wedge SvWd10 includes a servo area SvRI10 and a servo area SvRO10. The servo area SvRI10 is arranged at a position inside the servo area SvRO10. The servo area SvRI10 is arranged in the servo partition SvZn11. The servo area SvRI10 is arranged from the innermost circumference ICP1 side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly outside the boundary BD1. The servo area SvRO10 is arranged at a position outside the servo area SvRI10. The servo area SvRO10 is arranged in the servo partition SvZn10. The servo area SvRO10 is arranged from the outermost circumference OCP (OCP1) side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly inside the boundary BD1. The servo area SvRI10 and SvRO10 are arranged in the circumferential direction in the overlap area OvR1.

[0060] The servo wedge SvWd11 includes a servo area SvRI11 and a servo area SvRO11. The servo area SvRI11 is arranged at a position inside the servo area SvRO11. The servo area SvRI11 is arranged in the servo partition SvZn11. The servo area SvRI11 is arranged from the innermost circumference ICP1 side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly outside the boundary BD1. The servo area SvRO11 is arranged at a position outside the servo area SvRI11. The servo area SvRO11 is arranged in the servo partition SvZn10. The servo area SvRO11 is arranged from the outermost circumference OCP (OCP1) side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly inside the boundary BD1. The servo area SvRI11 and SvRO11 are arranged in the circumferential direction in the overlap area OvR1.

[0061] The servo wedge SvWd12 includes a servo area SvRI12 and a servo area SvRO12. The servo area SvRI12 is arranged at a position inside the servo area SvRO12. The servo area SvRI12 is arranged in the servo partition SvZn11. The servo area SvRI12 is arranged from the innermost circumference ICP1 side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly outside the boundary BD1. The servo area SvRO12 is arranged at a position outside the servo area SvRI12. The servo area SvRO12 is arranged in the servo partition SvZn10. The servo area SvRO12 is arranged from the outermost circumference OCP (OCP1) side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly inside the boundary BD1. The servo area SvRI12 and SvRO12 are arranged in the circumferential direction in the overlap area OvR1.

[0062] The servo wedge SvWd13 includes a servo area SvRI13 and a servo area SvRO13. The servo area SvRI13 is arranged at a position inside the servo area SvRO13. The servo area SvRI13 is arranged in the servo partition SvZn11. The servo area SvRI13 is arranged from the innermost circumference ICP1 side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly outside the boundary BD1. The servo area SvRO13 is arranged at a position outside the servo area SvRI13. The servo area SvRO13 is arranged in the servo partition SvZn10. The servo area SvRO13 is arranged from the outermost circumference OCP (OCP1) side of the upper surface FS1 and the lower surface RS1 across the boundary BD1 to a position slightly inside the boundary BD1. The servo area SvRI13 and SvRO13 are arranged in the circumferential direction in the overlap area OvR1.

[0063] Figure 5 is a schematic diagram showing an example of a servo sector SvC. Figure 5 FIG. 4 shows a predetermined servo sector SvC of a predetermined track Tre. Figure 5 As shown, in the circumferential direction, the direction of writing and reading data is called the traveling direction. For example, the traveling direction is the direction opposite to the rotation direction of the disk DK. In addition, the traveling direction may also be the same direction as the rotation direction of the disk DK. Figure 5 In the figure, for the sake of convenience, the track Tre is represented as a band extending in the circumferential direction by the track width, but it is actually curved along the circumferential direction.

[0064] The servo sector SvC includes, for example, a preamble, a servo address mark (SAM), a sector / cylinder, a burst, and a postcode. The preamble, the servo address mark, the sector / cylinder, the burst, and the postcode are arranged in this order. The preamble includes preamble information for synchronizing the reproduction of a servo pattern composed of the servo address mark and the sector / cylinder. The servo address mark includes servo address mark information indicating the start of the servo pattern. The sector / cylinder is composed of an address (cylinder address) of a predetermined cylinder (track) and an address of a servo sector of the predetermined cylinder (track). The burst is data (relative position data) used to detect a positional deviation (position error) of the head HD in the radial direction and / or the circumferential direction relative to the center of the track of the predetermined track (cylinder), and is composed of a repetitive pattern of a predetermined period. The burst data is written by a data pattern in which the phase of the burst data is reversed by 180° with one servo track as a period in the radial direction of the disk DK. In other words, the phase of the waveform of the burst data calculated by demodulating the predetermined burst data by discrete Fourier transform (DFT) or the like is inverted by 180° with respect to the phase of the adjacent burst data calculated by demodulating the predetermined burst data adjacent to the burst data in the radial direction (hereinafter referred to as adjacent burst data). "Adjacent" of course includes data, objects, areas, and spaces arranged in contact with each other, and also includes data arranged with a predetermined interval. The servo track (servo cylinder) corresponds to a track that is an object of writing or reading according to a command from the host 100 or the like. The servo track corresponds to a track defined by a servo pattern written to the upper surface FS and the lower surface RS of the disk DK by self servo writing (SSW) in which the servo pattern is written in the magnetic disk device 1, or by servo writing or servo track writing (STW) implemented by servo writing to a plurality of disks DK in a servo writing dedicated device or the like. The burst data is used, for example, to obtain the position of the head HD in the radial direction and / or the circumferential direction (hereinafter sometimes referred to as the head position) in the disk DK. The burst data includes, for example, N bursts (N Burst) and Q bursts (Q Burst). The N bursts and Q bursts are written in data patterns whose phases are shifted by 90° from each other in the radial direction of the disk DK. In other words, the phase of the N burst and the phase of the Q burst are shifted by 90° from each other in the radial direction, for example. The area code PC includes data (hereinafter referred to as RRO correction data) for correcting errors caused by the skew of the track relative to a path concentric with the disk DK, such as the center of the track, which is generated by jitter (repetitive runout: RRO) synchronized with the rotation of the disk DK when writing servo data to the disk.In the following, for the sake of convenience, the error caused by the deviation of the track relative to the track center caused by RRO may be simply referred to as RRO.

[0065] Below, refer to Figure 6 , Figure 7 as well as Figure 8 The eccentricity of the disk DK will be described.

[0066] Figure 6 FIG. 1 is a top view showing an example of the configuration of the servo tracks SvTRe of the non-eccentric disk DK. Figure 6 , an axis AX1 extending along a first direction X and passing through the disk center DKC, and an axis AX2 extending along a second direction Y and passing through the disk center DKC orthogonal to the axis AX1 are shown. Figure 6 The servo track SvTRe of the disk DK is shown in FIG.

[0067] exist Figure 6 In the example shown, the disk DK is not eccentric with respect to the spindle 12. In other words, the disk center DKC of the disk DK coincides with the rotation center SPC. The servo tracks SvTRe are arranged concentrically with the disk center DKC and the rotation center SPC.

[0068] Figure 7 FIG. 1 is a top view showing an example of the arrangement of the servo track SvTRe and the virtual servo track VSTR0 with respect to the eccentric disk DK. Figure 7 The servo track SvTRe of the disk DK and a virtual servo track (hereinafter sometimes referred to as a virtual servo track) VSTR0 for the disk DK are shown.

[0069] exist Figure 7 In the example shown, the disk DK is offset (displaced) relative to the spindle 12 in the first direction X. In other words, the disk center DKC of the disk DK is offset (displaced) relative to the rotation center SPC in the first direction X. For example, after the disk DK is shipped from the factory and the user starts using it, the disk DK may be offset (displaced) relative to the spindle 12. ", and sometimes "displacement (shift) of the disk relative to the spindle 12" is also referred to as "disk shift". "Disk DK is shifted (displaced) relative to the spindle 12 after the user starts using it after leaving the factory" is also sometimes referred to as "subsequent disk shift". Subsequent disk shift may be caused, for example, by the gap between the hub diameter of the spindle 12 and the inner diameter of the disk DK, thermal expansion and contraction, etc. Therefore, after the imaginary circle calibration, the disk DK will be offset relative to the spindle 12. The servo track SvTRe is arranged concentrically with the disk center DKC. The virtual servo track VSTR0 is arranged concentrically with the rotation center SPC. The servo track SvTRe is offset (shifted) relative to the virtual servo track VSTR0 in the first direction X.

[0070] Figure 8 FIG. 1 is a plan view showing an example of the arrangement of the servo track SvTRe and the virtual servo tracks VSTR0 and VSTR1 with respect to the eccentric disk DK. Figure 8 2 , a servo track SvTRe of the disk DK, a virtual servo track VSTR0, and a virtual servo track VSTR1 for the disk DK are shown.

[0071] exist Figure 8 In the example shown, the disk DK is offset (displaced) relative to the spindle 12 in the direction opposite to the front end side of the arrow in the first direction X and the front end side of the arrow in the second direction Y. In other words, the disk center DKC of the disk DK is offset (displaced) relative to the rotation center SPC in the direction opposite to the front end side of the arrow in the first direction X and the front end side of the arrow in the second direction Y. For example, as a subsequent disk displacement, the disk DK may be offset (displaced) relative to the spindle 12. The servo track SvTRe is arranged concentrically with the disk center DKC. The virtual servo track VSTR1 is arranged concentrically with the rotation center SPC. The servo track SvTRe is offset (displaced) relative to the virtual servo track VSTR0 in the first direction X. The servo track SvTRe is offset (displaced) relative to the virtual servo track VSTR1 in the direction opposite to the front end side of the arrow in the first direction X and the front end side of the arrow in the second direction Y.

[0072] The driver IC 20 controls the driving of the SPM 13 and the VCM 14 according to the control of the system controller 130 (to be specific, the MPU 50 or the HDC 60 described later). The driver IC 20 is electrically connected to the SPM 13 and the VCM 14. The driver IC 20 includes an SPM control unit 210 and a VCM control unit 220. The SPM control unit 210 controls the rotation of the SPM 13. The VCM control unit 220 controls the driving of the VCM 14 by controlling the current (or voltage) supplied to the VCM 14. In addition, a part of the configuration of the driver IC 20 (for example, the SPM control unit 210 and the VCM control unit 220) may also be provided in the system controller 130.

[0073] The head amplifier IC (preamplifier) ​​30 amplifies the read signal read from the disk DK and outputs it to the system controller 130 (more specifically, the read / write (R / W) channel 40 described later). The head amplifier IC30 is electrically connected to each head HD, for example, heads HD0, HD1, HD2, and HD3. In addition, the head amplifier IC30 outputs a write current corresponding to the signal output from the R / W channel 40 to the head HD. The head amplifier IC30 includes a head selection unit 310 and a signal detection unit 320. The head selection unit 310 selects the write head WH (WH0 to WH4) that writes data to the disk DK (DK0, DK1) and selects the read head RH (RH0 to RH4) that reads data from the disk DK (DK0, DK1) in the actuator ACT. The signal detection unit 320 detects a signal (write signal) written to the disk DK (DK0, DK1) by the write head WH and a signal (read signal) read from the disk DK (DK0, DK1) by the read head RH1. In addition, a part of the configuration of the head amplifier IC30 (for example, the head selection unit 310 and the signal detection unit 320) may be provided in the system controller 130.

[0074] The volatile memory 70 is a semiconductor memory in which the stored data will be lost when the power supply is disconnected. The volatile memory 70 stores data required for processing of each part of the magnetic disk device 1, etc. The volatile memory 70 is, for example, a DRAM (Dynamic Random Access Memory) or an SDRAM (Synchronous Dynamic Random Access Memory). The volatile memory 70 has an eccentricity table that records the eccentricity of the disk after the subsequent disk shift, such as information obtained by learning the RRO. In addition, the volatile memory 70 may not have an eccentricity table.

[0075] The nonvolatile memory 80 is a semiconductor memory that records the stored data even when the power supply is disconnected. The nonvolatile memory 80 is, for example, a NOR type or NAND type flash ROM (Flash Read Only Memory: FROM). The nonvolatile memory 80 has an eccentricity table that records the eccentricity of the disk after the subsequent disk shift, for example, information obtained by learning the RRO. In addition, the nonvolatile memory 80 may not have an eccentricity table.

[0076] The buffer memory 90 is a semiconductor memory that temporarily records data transmitted and received between the magnetic disk device 1 and the host 100. In addition, the buffer memory 90 may be formed integrally with the volatile memory 70. The buffer memory 90 is, for example, a DRAM, an SRAM (Static Random Access Memory), an SDRAM, a FeRAM (Ferroelectric Random Access Memory), or an MRAM (Magnetoresistive Random Access Memory).

[0077] The system controller (controller) 130 is implemented, for example, using a large-scale integrated circuit (LSI) called a system-on-a-Chip (SoC) in which a plurality of components are integrated into a single chip. The system controller 130 includes a read / write (R / W) channel 40, a microprocessor (MPU) 50, and a hard disk controller (HDC) 60. The system controller 130 is electrically connected to the driver IC 20, the head amplifier IC 30, the volatile memory 70, the nonvolatile memory 80, the buffer memory 90, and the host system 100. In addition, the system controller 130 may also include an SPM control unit 210, a VCM control unit 220, a head selection unit 310, and a signal detection unit 320. The system controller 130 may also include the driver IC 20 and the head amplifier IC 30.

[0078] The R / W channel 40 performs signal processing of read data transmitted from the disk DK to the host 100 and write data transmitted from the host 100 according to instructions from the MPU 50 described later. The R / W channel 40 has a circuit or function for measuring the signal quality of the read data. The R / W channel 40 is electrically connected to, for example, the head amplifier IC 30, the MPU 50, and the HDC 60.

[0079] The MPU 50 is a main controller that controls each part of the magnetic disk device 1 according to instructions from the host 100 and the like. The MPU 50 performs servo control to control the actuator ACT and position the head HD via the driver IC 20. The MPU 50 controls the write operation of writing data to the disk DK and selects the storage destination of the written data. In addition, the MPU 50 controls the read operation of reading data from the disk DK and controls the processing of the read data. The MPU 50 is connected to each part of the magnetic disk device 1. For example, the MPU 50 is electrically connected to the driver IC 20, the R / W channel 40, and the HDC 60 and the like.

[0080] HDC 60 controls read / write processing according to instructions from MPU 50 and controls data transfer between host 100 and R / W channel 40. HDC 60 is electrically connected to R / W channel 40, MPU 50, volatile memory 70, nonvolatile memory 80, buffer memory 90, and the like.

[0081] The HDC 60 includes a head control unit 610, a servo control unit 620, and a command control unit 630. The HDC 60 executes the processing of each of these units, such as the head control unit 610, the servo control unit 620, and the command control unit 630, on the firmware. In addition, the HDC 60 may include these units as circuits. In addition, a part of the configuration of the HDC 60 (such as the head control unit 610, the servo control unit 620, and the command control unit 630) may also be provided in the MPU 50.

[0082] The head control unit 610 controls the head HD according to a request (command) from the host 100 or the like. The head control unit 610 selects a predetermined head HD from a plurality of head HDs according to a command from the host 100 or the like. The head control unit 610 moves a predetermined head HD to a predetermined position on the disk DK according to a command from the host 100 or the like. The head control unit 610 switches from a predetermined head HD to another head HD among a plurality of head HDs according to a command from the host 100 or the like. Hereinafter, “switching from a predetermined head HD to another head HD among a plurality of head HDs” may sometimes be referred to as “head change”. Hereinafter, “the head before the head change” may sometimes be referred to as “the head before the head change”, and “the head HD after the head change” may sometimes be referred to as “the head after the head change”.

[0083] The servo control unit 620 controls the position of the head HD. In other words, the servo control unit 620 controls the head HD to access a predetermined area of ​​the disk DK. The servo control unit 620 includes a tracking control unit 6210 , a seek control unit 6220 , and an eccentricity table update unit 6230 .

[0084] The tracking control unit 6210 controls the head HD to track a predetermined track (cylinder) of the disk DK. The term "tracking" includes "tracking a predetermined path, such as a predetermined track, when writing data to the disk DK" and "tracking a predetermined path, such as a predetermined track, when reading data from the disk DK".

[0085] The seek control unit 6220 controls the seek of the head HD from a predetermined track (cylinder) to a target track (hereinafter sometimes referred to as a target track) in the disk DK. The seek control unit 6220 includes a DC (Direct Current) part head relative position calculation unit 6221, an AC (Alternating Current) part head relative position calculation unit 6222, a head relative position correction unit 6223, and a head change servo partition correction unit 6224. Hereinafter, "the relative position between different heads among the multiple heads HD corresponding to the multiple disks DK" may also be referred to as "head relative position".

[0086] The DC portion head relative position calculation unit 6221 calculates the DC portion head relative position in a predetermined track (cylinder) of the disk DK. The DC portion head relative position calculation unit 6221 calculates, for example, a differential value (hereinafter sometimes referred to as a DC portion offset differential value) of a plurality of correction values ​​(offset values) that do not change (are constant) within one turn of the predetermined track (cylinder) of the disk DK and correspond to the offset or offset amount in the radial direction of the two heads HD before and after the head change (hereinafter sometimes referred to as a DC portion offset amount or a DC portion offset amount). The DC portion offset amount or the DC portion offset amount is caused by, for example, the mounting offset of the suspension of the magnetic disk device 1 or the servo write pitch. The DC portion head relative position calculation unit 6221 calculates the DC portion head relative position (or the DC portion head relative position correction value) based on, for example, the DC portion offset differential value.

[0087] The AC portion head relative position calculation unit 6222 calculates the AC portion head relative position. For example, the AC portion head relative position calculation unit 6222 calculates the relative eccentric position between the two disks DK corresponding to the two heads HD before and after the head change in the sectors of the predetermined track (cylinder) of the disk DK before and after the head change, as the AC portion head relative position (or the AC portion head relative position correction value).

[0088] The head-to-head relative position correction unit 6223 corrects the head-to-head relative positions among a plurality of head HDs in the case of a head change. The head-to-head relative position correction unit 6223 calculates the head-to-head relative positions of the two head HDs before and after the head change (or the head-to-head relative position correction value) based on the DC part head-to-head relative positions and the AC part head-to-head relative positions. When a head change is performed, the head-to-head relative position correction unit 6223 can correct the position where the head HD before the head change is configured in a predetermined track, such as a radial position (hereinafter sometimes referred to as the current estimated position or the previous estimated position) to the position where the head HD after the head change is estimated to be configured in a predetermined track, such as a radial position (hereinafter sometimes referred to as the next estimated position or the next estimated position).

[0089] The head-change servo partition correction unit 6224 corrects the servo partition when the head is changed. The head-change servo partition correction unit 6224 corrects the servo partition when the head is changed, for example, based on the relative position between the heads.

[0090] The eccentricity table updating unit 6230 updates the eccentricity table. For example, when the RRO is learned after the subsequent disk shift, the eccentricity table updating unit 6230 records at least one of the eccentricity table 710 of the volatile memory 70 and the eccentricity table 810 of the non-volatile memory 80, or updates at least one of the eccentricity table 710 of the volatile memory 70 and the eccentricity table 810 of the non-volatile memory 80.

[0091] The command control unit 630 controls the commands received from the host 100, etc. For example, the command control unit 630 stores the commands received from the host 100, etc. in a waiting queue in the order in which they were received from the host 100, etc., and accesses the position or area, such as a sector, specified by the command through the servo control unit 620 based on a predetermined command among at least one command stored in the queue. Hereinafter, "accessing the position or area specified by the command based on the predetermined command" is sometimes referred to as "processing a command". "Commands stored in the queue" are sometimes referred to as "queue commands". In addition, "processing queue commands" is sometimes referred to as "queuing".

[0092] When processing a predetermined queue command (hereinafter sometimes referred to as the current command), the command control unit 630 performs a calculation based on the position of the disk DK where the head HD is currently configured, for example, the position of the data sector of the disk DK where the head HD is currently configured (hereinafter sometimes referred to as the current position) and a plurality of queue commands stored in the queue in the order received from the host 100, etc., selects a predetermined command from the plurality of queue commands based on the result of the calculation, changes the order of the selected commands to the order of commands to be processed after the current command (hereinafter sometimes referred to as the next order), and processes the selected command after processing the current command. Hereinafter, "changing the order of processing a plurality of commands" and "changing the logical-physical mapping" are sometimes referred to as "rearrangement". Sometimes, "performing a predetermined calculation (calculation) process, selecting a predetermined command from a plurality of commands based on the result of the predetermined calculation (calculation) process, and rearranging the order of the commands selected from the plurality of commands" is also referred to as "rearrangement calculation process", "rearrangement calculation" or "rearrangement process". In addition, “a command to be processed following the current command” may be referred to as “the next processing command”.

[0093] Fig. 9 1 is a block diagram showing an example of the servo control system SY according to the present embodiment.

[0094] The magnetic disk device 1 has a system (hereinafter sometimes referred to as a servo control system) SY for performing servo control of the head HD. The servo control system SY has an RRO current compensation unit S1, a current instruction value determination unit S2, a state estimation unit S3, a current application unit S4, a plant S5, an operator CL1, an operator CL2, and an operator CL3. The RRO current compensation unit S1, the current instruction value determination unit S2, the state estimation unit S3, the current application unit S4, the plant S5, the operator CL1, the operator CL2, and the operator CL3 are included in, for example, an actuator ACT, a driver IC20, a head amplifier IC30, a system controller 130, a disk DK, a volatile memory 70, a nonvolatile memory 80, and a buffer memory 90. The plant S5 is composed of, for example, an actuator ACT, a driver IC20, a head amplifier IC30, and a system controller 130.

[0095] The RRO current compensator S1 suppresses the eccentricity. The RRO current compensator S1 uses the PES (Position Error Signal) obtained during the tracking period to learn each time so that the current output that reduces the RPE (Repeatable Position Error) is obtained, and calculates the current value (hereinafter sometimes referred to as the RRO current compensation value) Ivcm_rro that is used to compensate for the eccentricity, such as RRO, based on the learning result.

[0096] The current instruction value determination unit S2 determines the current instruction value Itgt. The state estimation unit S3 calculates the head HD in the next sampling, for example, the estimated position pesti of the next head HD and the head HD, for example, the estimated velocity vesti of the next head HD. One sampling may correspond to the time corresponding to the interval between a plurality of continuous servo wedges SvWd, for example.

[0097] The current applying unit S4 applies a current (hereinafter sometimes referred to as VCM current) Ivcm for driving the VCM 14 according to the current indication value Itgt. The device S5 drives the actuator ACT according to the VCM current Ivcm applied to the VCM 14, moves the head HD to a predetermined position, reads the servo pattern with the head HD, and thereby demodulates the actual position (hereinafter sometimes referred to as actual position or demodulated position) p of the head HD.

[0098] The target speed vtgt of the head HD and the estimated speed vesti of the head HD are input to the calculation unit CL1. The calculation unit CL1 outputs a difference value (hereinafter sometimes referred to as a head speed difference value) obtained by subtracting the estimated speed vesti of the head HD from the target speed vtgt of the head HD to the current instruction value determination unit S2.

[0099] The target position ptgt of the head HD and the estimated position pesti of the head HD are input to the operator CL2. The operator CL2 outputs a difference value (hereinafter sometimes referred to as a head position difference value) obtained by subtracting the estimated position pesti of the head HD from the target position ptgt of the head HD to the RRO current compensation unit S1 and the current instruction value determination unit S2. Here, when the virtual circle control described later is performed, the target position ptgt is corrected mainly in the servo state of the position control using information during adjustment for the virtual circle control.

[0100] The head position difference value is input to the RRO current compensator S1. The RRO current compensator S1 calculates the RRO compensation current value Ivcm_rro based on the head position difference value and outputs the RRO compensation current value Ivcm_rro to the current instruction value determiner S2. Here, the RRO compensation current value corresponds to the current value that guarantees RRO.

[0101] The target acceleration atgt, the head velocity difference value, the head position difference value, and the RRO compensation current value Ivcm_rro are input to the current instruction value determination unit S2. The current instruction value determination unit S2 calculates the current instruction value Itgt based on the target acceleration atgt, the head velocity difference value, the head position difference value, and the RRO compensation current value Ivcm_rro, and outputs the current instruction value Itgt to the state estimation unit S3 and the current application unit S4.

[0102] The state estimating unit S3 receives the head relative position pchg_hd, the current indication value Itgt, and the estimated position error perr as inputs. The state estimating unit S3 calculates the estimated speed vesti of the head HD and the estimated position pesti of the head HD in the next sampling based on the head relative position pchg_hd, the current indication value Itgt, and the estimated position error perr, and outputs the estimated speed vesti of the head HD to the operator CL1, and outputs the estimated position pesti of the head HD to the operators CL2 and CL3.

[0103] The current instruction value Itgt is input to the current applying unit S4. The current applying unit S4 outputs the VCM current value Ivcm to the device S5 according to the current instruction value Itgt.

[0104] The device S5 drives the actuator ACT according to the VCM current value Ivcm to move the head HD to the actual position p, and outputs the actual position p to the calculator CL3.

[0105] The actual position p and the estimated position pesti are input to the calculation unit CL3, and the calculation unit CL3 outputs a specified position error perr obtained by subtracting the estimated position pesti from the actual position p to the state estimation unit S3.

[0106] Fig.10 is a top view showing an example of virtual circle control. Fig.10 In the disk DK, servo track SvTR10k-1, servo track SvTR10k-2, servo track SvTR10k, servo track SvTR10k+1, servo track SvTR10k+2, and virtual servo track VSTR10 are shown. Fig.10 In , the disk center DKC is offset (displaced) relative to the rotation center SPC. Fig.10 In the case where the disk center DKC is offset relative to the rotation center SPC, the servo track SvTR10n may coincide with the virtual servo track VSTR10. Fig.10 In FIG. 1 , the servo tracks TR10k-1 to TR10k+2 are arranged concentrically with the disc center DKC, and the virtual servo track VSTR10 is arranged concentrically with the rotation center SPC.

[0107] The magnetic disk device 1 performs servo control (hereinafter sometimes referred to as virtual circle control) for tracking a virtual servo track. When the magnetic disk device 1 tracks the servo track of the disk DK that is eccentric with respect to the rotation center SPC, the head HD moves within one circle in the circumferential direction. For example, when the magnetic disk device 1 has a disk shift, the head HD moves in the radial direction of one cycle within one circle in the circumferential direction of the servo track of the disk DK that is eccentric with respect to the rotation center SPC. When the magnetic disk device 1 tracks the virtual servo track, the head HD hardly moves within one circle in the circumferential direction. Fig.10 In the example shown, when the disk device 1 tracks the virtual servo track VSTR10 through virtual circle control, the eccentricity information related to the virtual circle (hereinafter sometimes also referred to as virtual circle eccentricity information) such as the radial offset or offset (hereinafter sometimes also referred to as virtual circle offset or virtual circle offset) of each circular position change within one circle is learned, measured or calibrated.

[0108] Fig.11 This is a schematic diagram showing an example of virtual circle control. Fig.11 Corresponds to Fig.10 .exist Fig.11 The servo gate corresponding to the reading of the servo wedge SvWd of the predetermined track of the disk DK (hereinafter sometimes referred to as servo reading), the path when tracking the servo tracks SvTR10k-2 to 10k+2, and the path when tracking the virtual servo track VSTR are shown. The servo gate is valid (asserted) when it rises, and is invalid (negate) when it falls. Fig.11 In the process, SG0 rises and falls, SG1 rises and falls, SG2 rises and falls, SG3 rises and falls, SG4 rises and falls, and SG5 rises and falls.

[0109] The magnetic disk device 1 corrects the target servo track (hereinafter sometimes referred to as the target servo track) to the virtual servo track based on the virtual circle eccentricity information by virtual circle control, and performs servo reading on the virtual servo track. Fig.11 In the example shown, the magnetic disk device 1 adds virtual circle offsets corresponding to the circumferential positions of the servo track SvTR10k through virtual circle control, corrects it to the virtual servo track VSTR10, and performs servo reading on the virtual servo track VSTR10.

[0110] Fig.12 It is a plan view showing an example of eccentricity of the disk DK1 with respect to the spindle 12 according to the present embodiment.

[0111] The disk center DKC1 of the disk DK1 is offset (displaced) relative to the rotation center SPC. Fig.12 In the example shown, Figure 4 The disk center DKC1 shown is offset (displaced) to the side opposite to the front end side of the arrow in the first direction X with respect to the rotation center SPC.

[0112] Fig.13 1 is a schematic diagram showing an example of head change of different heads HD corresponding to different disks DK. Fig.13 In the overlap Figure 3 The disk DK0 and Fig.12 The disk DK1 is shown. Fig.13 In the example, the rotation centers SPC of disks DK0 and DK1 coincide with each other. Fig.13 The servo track SvTRn is shown in FIG. 1 , which is arranged slightly outside the boundary BD0 .

[0113] exist Fig.13 In the example shown, the magnetic disk device 1 tracks the servo track SvTRn with the head HD0 in the disk DK0. For example, the magnetic disk device 1 reads the servo areas SvRI00 and SvRO00 with the head HD0 in the disk DK0. After the magnetic disk device 1 reads the servo areas SvRI00 and SvRO00 with the head HD0 in the disk DK0, the head HD0 is replaced with the head HD1, and the head HD1 is driven on a path corresponding to the servo track SvTRn in the disk DK1 by inertia.

[0114] Fig.14 FIG. 1 is a schematic diagram showing an example of calculating the timing of the relative position between heads when the head is changed. Fig.14 The host computer 100 and the magnetic disk device 1 are shown in FIG. Fig.14 In the embodiment, the magnetic disk device 1 includes an HDC 60. Fig.14 In FIG. 6 , the HDC 60 includes a servo control unit 620 and a command control unit 630. Fig.14 In the command control unit 630, there is a queue Qn. Fig.14 In the example, the horizontal axis represents time. Fig.14 In , time passes by the front end of the arrow pointing toward the horizontal axis of time. Fig.14Times t0 and t2 are shown in . Time t2 is equivalent to a time later than (after) time t0. Queue command Cmdn is equivalent to a queue command that is transmitted from the host 100 to the command control unit 630 earlier than (before) the queue command Cmdn+1 and stored in the queue Qn. Queue command Cmdn+1 is equivalent to a queue command that is transmitted from the host 100 to the command control unit 630 earlier than (before) the queue command Cmdn+2 and stored in the queue Qn. Queue command Cmdn+2 is equivalent to a queue command that is transmitted from the host 100 to the command control unit 630 earlier than (before) the command Cmdn+3 and stored in the queue Qn. Queue command Cmdn+3 is equivalent to a queue command that is transmitted from the host 100 to the command control unit 630 earlier than (before) the queue command Cmdn+4 and stored in the queue Qn. In Fig.14 In the example, the number of commands that can be stored in the queue Qn (hereinafter sometimes referred to as the queue depth (Queue Depth: QD)) is 4.

[0115] exist Fig.14 In the example shown, the disk device 1 performs rearrangement operation processing on the queue commands Cmdn, Cmdn+1, and Cmdn+2, and processes the selected queue command Cmdn+1. The disk device 1 starts control of the current head HD's seek operation based on the queue command Cmdn+1, and starts the current head HD's seek operation from the sector (hereinafter sometimes referred to as the current sector) of the track (hereinafter sometimes referred to as the current track) where the current head HD is configured to a predetermined sector (hereinafter sometimes referred to as the next sector) of the track (hereinafter sometimes referred to as the next track) specified by the queue command Cmdn+1 that is the target following the current track. When the magnetic disk device 1 performs a seek with the current head HD from the current track to the next track specified by the queue command Cmdn+1, it rotates and waits in order to position the current head HD at the next sector. When the current head HD is positioned at the next sector, it writes the data specified by the queue command Cmdn+1 to the sector, or reads the data written to the sector specified by the queue command Cmdn+1.

[0116] The disk device 1 receives the queue command Cmdn+3 transmitted from the host 100 at time t0 when processing the queue command Cmdn+1. The QD of the queue Qn of the disk device 1 is 4, and the number of queue commands is 3, so the queue command Cmdn+3 received from the host 100 is stored in the queue Qn. When processing the queue command Cmdn+1, the disk device 1 performs a rearrangement operation on the queue commands Cmdn, Cmdn+2, and Cmdn+3, and selects the queue command Cmdn. When the processing of the queue command Cmdn+1 is completed, the disk device 1 returns a response to the host 100.

[0117] The disk device 1 starts processing the queue command Cmdn at time t2 after the processing of the queue command Cmdn+1 is completed. When the disk device 1 starts processing the queue command Cmdn, it determines whether the number (hereinafter sometimes referred to as the head number) of the (physical) head (hereinafter sometimes referred to as the next head) HD specified by the command following the current head HD corresponding to the queue command Cmdn, such as the head number of head HD1, is the same as the head number of the current (physical) head HD, such as the head number of head HD0. In other words, when the disk device 1 starts processing the queue command Cmdn, it determines whether the next head HD corresponding to the queue command Cmdn is the same as the current head HD0.

[0118] When it is determined that the head number of the next head HD corresponding to the queue command Cmdn is the same as the head number of the current head HD0, the magnetic disk device 1 starts the seek operation of the current head HD0 to the next track specified by the queue command Cmdn. The magnetic disk device 1 performs rotation waiting in order to position the current head HD0 at the next sector of the next track when the current head HD0 seeks to the next track. When the magnetic disk device 1 positions the current head HD0 at the next sector, it writes the data specified by the queue command Cmdn to the sector. In other words, when it is determined that the next head HD corresponding to the queue command Cmdn is the same as the current head HD0, the magnetic disk device 1 performs rotation waiting in order to position the current head HD0 at the next sector when the current head HD0 seeks to the next sector of the next track specified by the queue command Cmdn, and when the current head HD0 is positioned at the next sector, it writes the data specified by the queue command Cmdn to the sector.

[0119] When it is determined that the head number of the next head HD corresponding to the queue command Cmdn is the head number of the head HD1 which is different from the head number of the current head HD0, the magnetic disk device 1 calculates the head relative position correction value of the head relative position between the heads HD0 and HD1, and starts the seek action of the next head HD1 to the next track specified by the queue command Cmdn based on the queue command Cmdn and the head relative position correction value. In other words, when it is determined that the next head HD corresponding to the queue command Cmdn is different from the current head HD0, the magnetic disk device 1 calculates the head relative position correction value of the head relative position between the heads HD0 and HD1, and starts the seek action of the next head HD1 to the next track specified by the queue command Cmdn based on the queue command Cmdn and the head relative position correction value.

[0120] When processing the queue command Cmdn, the magnetic disk device 1 receives the queue command Cmdn+4 transmitted from the host 100. The QD of the queue Qn of the magnetic disk device 1 is 4 and the number of queue commands is 3, so the queue command Cmdn+4 received from the host 100 is stored in the queue Qn.

[0121] Fig.15 This is a schematic diagram showing an example of a servo gate that does not correct timing when the head is changed. Fig.15 and Fig.13 and Fig.14 Corresponding. Fig.15 The servo pattern and servo gate are shown in . Fig.15 The servo pattern corresponds to Fig.13 The servo track SvTRn. Fig.15 In the servo pattern, the servo area SvRI00, the servo area SvRO00 and the servo area SvRI11 are included. Fig.15 In the servo gate, it is effective when it is rising, and it is ineffective when it is falling. Fig.15 In the figure, the horizontal axis of the servo gate is time t. Fig.15 The horizontal axis shows timings T151, T152, T153, and T154. For example, timings T151 to T154 respectively correspond to timings after a predetermined time from a timing serving as a reference. In addition, timings T151 to T154 may respectively correspond to absolute times. Timing T152 corresponds to the time after timing T151, timing T153 corresponds to the time after timing T152, and timing T154 corresponds to the time after timing T153. Timing T151 corresponds to the timing when the servo gate is valid, timing T152 corresponds to the timing when the servo gate is invalid, timing T153 corresponds to the timing when the servo gate is valid, and timing T154 corresponds to the timing when the servo gate is invalid. Timings T151 and T152 correspond to the servo area SvRO00. In Fig.15 150 and 151. The interval Tl1 between the timing T152 and the timing T153 is shown in FIG. The interval Tl1 corresponds to the time interval of the servo gate.

[0122] exist Fig.15 In the example shown, the magnetic disk device 1 is as shown in FIG. Fig.13As shown, in disk DK0, the servo track SvTRn is tracked by head HD0, and the servo gate is enabled at timing T151 and disabled at timing T152 to read the servo area SvRO00. When the head is changed from head HD0 to head HD1 after reading the servo area SvRO00, the magnetic disk device 1 does not correct (or adjust) the timing of the servo gate. Without correcting (or adjusting) the timing of the servo gate, the magnetic disk device 1 enables the servo gate at timing T153 after an interval Tl1 from timing T152. When the timing of the servo gate is not corrected when the head is changed from head HD0 to head HD1, the magnetic disk device 1 may not be able to read the servo area.

[0123] Fig.16 This is a schematic diagram showing an example of a servo gate whose timing is corrected when the head is changed. Fig.16 Corresponds to Fig.13 and Fig.14 .exist Fig.16 The servo pattern and servo gate are shown in . Fig.16 The servo pattern corresponds to Fig.13 The servo track SvTRn. Fig.16 In the servo pattern, the servo area SvRI00, the servo area SvRO00 and the servo area SvRI11 are included. Fig.16 In the servo gate, it is effective when it is rising, and it is ineffective when it is falling. Fig.16 In the figure, the horizontal axis of the servo gate is time t. Fig.16 The horizontal axis shows timings T151, T152, T153, and T161. For example, timing T161 corresponds to a timing after a predetermined time from a timing serving as a reference. In addition, timing T161 may also correspond to an absolute time. Timing T161 corresponds to the time after timing T152, and timing T153 corresponds to the time after timing T161. Timing T161 corresponds to the timing when the servo gate is valid, and timing T153 corresponds to the timing when the servo gate is invalid. Timings T161 and T153 correspond to the servo area SvRI11. Fig.16 The interval T12 between the timing T161 and the timing T153 is shown in FIG. The interval T12 corresponds to the time interval of the servo gate. The interval T12 is smaller than the interval T11, for example. Fig.16 Compared with the case where the distance Tl2 is farther away in the circumferential direction as shown, the distance Tl1 may be greater than the distance Tl1.

[0124] exist Fig.16 In the example shown, the magnetic disk device 1 is as shown in FIG. Fig.13As shown, in disk DK0, the servo track SvTRn is tracked by head HD0, and the servo gate is enabled at timing T151 and disabled at timing T152 to read the servo area SvRO00. When the head is changed from head HD0 to head HD1 after reading the servo area SvRO00, the disk device 1 corrects (or adjusts) the timing of the servo gate. When the timing of the servo gate is corrected (or adjusted), the disk device 1 enables the servo gate at timing T161 after an interval Tl2 from timing T152. When the timing of the servo gate is corrected when the head is changed from head HD0 to head HD1, the disk device 1 enables the servo gate at timing T161 and disables the servo gate at timing T153 to read the servo area SvRI11.

[0125] Below, refer to Fig.17 , Fig.18 , Fig.19 as well as Fig. 20 etc. to explain the header change processing method.

[0126] When the sector and head (next head) HD (head number) specified by the command received from the host 100 or the like at the time of head change are determined, the disk device 1 corrects the estimated position pesti used in the next sampling. For example, the disk device 1 calculates the DC part head relative position pchg_hd_dc by taking a difference between a certain offset amount of the current head HD and a certain offset amount of the next head HD at the time of head change.

[0127] For example, when calculating the AC portion head relative position pchg_hd_ac, the magnetic disk device 1 estimates the RRO position Prro from the servo control transfer characteristic based on the RRO compensation current value Ivcm_rro using the following equation (all times, Laplace transform equation).

[0128] Prro=PL×Ivcm_rro Formula (1)

[0129] Here, PL corresponds to equipment.

[0130] When a large eccentricity is generated due to disk displacement, such as a late disk displacement, when the head HD is performing RRO correction to completely follow the predetermined servo track, the magnetic disk device 1 estimates the primary RRO position (only once, Laplace transform) by multiplying the primary component of the RRO compensation current value based on the following reproduction signal, which is a reproduction signal obtained by reading the predetermined servo track of the disk DK for one turn, by the current position conversion coefficient coeff1. Here, the current position conversion coefficient is equivalent to a coefficient for converting the dimension of current into the dimension of position.

[0131] Prro1=cоeff1×Ivcm_rro1 Formula (2)

[0132] Here, Ivcm_rro1 is the primary RRO compensation current value.

[0133] When the current position conversion coefficient cоeff1 is different depending on the environment, the temperature of VCM14, and the radial position of the head HD, the magnetic disk device 1 learns each interval in the divided radial direction, and uses the learning value corresponding to each interval (for example, the current position conversion coefficient) to interpolate through linear approximation and polynomial approximation as needed to calculate the current position conversion coefficient cоeff1.

[0134] The magnetic disk device 1 has a table of COS components of coefficients of the number of indices (hereinafter sometimes referred to as the number of indices) corresponding to the number of servo wedges SvWd (hereinafter sometimes referred to as the number of servo wedges) or the number of servo sectors (hereinafter sometimes referred to as the number of servo sectors) in a predetermined track of the disk DK (hereinafter sometimes referred to as the number of servo wedges) or the number of servo sectors (hereinafter sometimes referred to as the number of servo sectors) and a table of SIN components of coefficients (hereinafter sometimes referred to as SINTABLE). The magnetic disk device 1 has a parameter for suppressing the eccentricity of each head HD once. In addition, the magnetic disk device 1 may also have parameters for suppressing the eccentricity of each head HD at each order.

[0135] Fig.17 This is a schematic diagram showing an example of changes COSL and SINL of the COS component and the SIN component of the coefficient corresponding to the index in the predetermined track of the disk DK. Fig.17 In FIG. 1 , the horizontal axis represents the index corresponding to the servo wedge SvWd or servo sector of a predetermined track, and the vertical axis represents the value equivalent to the amplitude. Fig.17 On the vertical axis, the positive value increases as the value moves toward the front end of the positive arrow, and the negative value decreases as the value moves toward the front end of the negative arrow. In other words, the absolute value increases as the value moves toward the front end of the positive arrow and the negative arrow. Fig.17 The values ​​A and -A are shown on the vertical axis. The absolute values ​​of A and -A are the same. Fig.17On the horizontal axis, the index increases as it moves toward the front end side of the arrow, and decreases as it moves toward the opposite side of the front end side of the arrow. Fig.17 The horizontal axis of shows indexes 0, 1, . . . , Nsv_sct-1. Nsv_sct-1 corresponds to the number of servo wedges (or the number of servo sectors)-1 of a predetermined track.

[0136] The disk device 1 obtains Fig.17 The COS component of the coefficient changes COSL and the SIN component changes SINL as shown.

[0137] Fig.18 1 is a schematic diagram showing an example of a table TB181 including COSTABLE and SINTABLE. Table TB181 includes COSTABLE and SINTABLE. Fig.18 In table TB181, COSTABLE includes COS components of coefficients corresponding to each index of a predetermined track of disk DK. For example, COSTABLE corresponds to Fig.17 The variation COSL of the COS component of the coefficient shown. SINTABLE includes SIN components of the coefficient corresponding to each index of a predetermined track of the disk DK. For example, SINTABLE corresponds to Fig.17 The coefficient of the SIN component is shown as the variation of SINL.

[0138] The magnetic disk device 1 records the table TB181 in a predetermined recording area, such as the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. For example, the magnetic disk device 1 records the table TB181 in at least one of the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. In addition, the table TB181 may be included in the eccentricity table.

[0139] When the current head HD, for example, head Had, is changed to the next head HD, for example, head HDb, the magnetic disk device 1 calculates the eccentric position according to the following equation (only once, the equation is described discretely on the time axis).

[0140] Prro1[sct]=cоeff1×(R1c×COSTABLE[sct]+R1s×SINTABLE[sct])

[0141] Formula (3)

[0142] Here, R1c is a primary COS component of the eccentricity compensation current value corresponding to the predetermined head HD, and R1s is a primary SIN component of the eccentricity compensation current value corresponding to the predetermined head HD.

[0143] When the magnetic disk device 1 tracks a predetermined track of a predetermined disk DK using a predetermined head HD, the magnetic disk device 1 learns parameters associated with the eccentricity compensation current value corresponding to the predetermined head HD in real time.

[0144] Fig.19 1 is a schematic diagram showing an example of a table TB191 showing eccentricity compensation current values ​​corresponding to a predetermined head HD. Fig.19 In the table TB191, the eccentricity compensation current value corresponding to the predetermined head HD (for example, the first-order COS component of the eccentricity compensation current value and the first-order SIN component of the eccentricity compensation current value).

[0145] The magnetic disk device 1 records the table TB191 in a predetermined recording area, such as the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. For example, the magnetic disk device 1 records the table TB191 in at least one of the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. In addition, the table TB191 may also be included in the eccentricity table.

[0146] When the magnetic disk device 1 changes the head from the head HDa to the head HDb, the relative eccentric position of the head Had and the head HDb is calculated by the following equation (only once, the equation is described discretely on the time axis).

[0147] dprro1[sct]=cоeff1×(dR1c_ab×COSTABLE[sct]+dR1s_ab×SINTABLE[sct]) Formula (4)

[0148] Here, dR1c_ab is the first-order COS component of the DFT coefficient corresponding to the relative position between the two heads Had and HDb before and after the head change, and dR1s_ab is the first-order SIN component of the DFT coefficient corresponding to the relative position between the two heads Had and HDb before and after the head change. The DFT coefficients dR1c_ab and dR1s_ab are derived by the following formulas.

[0149] dR1c_ab=R1c_b-R1c_a Formula (5)

[0150] dR1s_ab=R1s_b-R1s_a Formula (6)

[0151] Here, R1c_b is the first-order COS component of the eccentricity compensation current value corresponding to head HDb, R1c_a is the first-order COS component of the eccentricity compensation current value corresponding to head HDa, R1s_b is the first-order SIN component of the eccentricity compensation current value corresponding to head HDb, and R1s_a is the first-order SIN component of the eccentricity compensation current value corresponding to head HDa.

[0152] The disk device 1 may also calculate in advance a plurality of relative positions between heads (amplitude / phase, COS coefficient / SIN coefficient) corresponding to a plurality of combinations of two heads among the plurality of heads HD, and have a table containing a plurality of DFT coefficients corresponding to a plurality of relative positions between heads corresponding to a plurality of combinations of two heads among the plurality of heads HD. The disk device 1 may also update the table containing a plurality of DFT coefficients corresponding to a plurality of relative positions between heads corresponding to a plurality of combinations of two heads among the plurality of heads HD whenever the table of eccentricity compensation current values ​​is updated, or may update the table in background processing when the value of the table of eccentricity compensation current values ​​exceeds a predetermined threshold value. By having a table containing a plurality of DFT coefficients corresponding to a plurality of relative positions between heads corresponding to a plurality of combinations of two heads among the plurality of heads HD, the disk device 1 can refer to the table without calculating the DFT coefficients, thereby reducing the calculation time.

[0153] Fig. 20 2 is a schematic diagram showing an example of a table TB201 of DFT coefficients corresponding to the relative positions between two heads HD before and after the head change. Fig. 20 In the table TB201, the first-order COS component dR1c and the first-order SIN component dR1s of the DFT coefficients corresponding to the relative positions between the two current heads HD(From) and the next head HD(To) before and after the head change. The current head HD(From) and the next head HD(To) include heads HD0, HD1, ..., HDn, respectively.

[0154] The magnetic disk device 1 records the table TB201 in a predetermined recording area, such as the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. For example, the magnetic disk device 1 records the table TB201 in at least one of the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90. In addition, the table TB201 may also be included in the eccentricity table.

[0155] The magnetic disk device 1 calculates the position where the head change is performed, for example, the relative eccentric position in the sector as the relative position between the AC part heads (or the relative position correction value between the AC part heads) pchg_hd_ac. In addition, for the magnetic disk device 1, the first-order relative eccentric position (relative position between heads) of the multiple heads HD when the head change is performed is described above, but the relative eccentric position (relative position between heads) can also be calculated by calculating and adding a higher-order relative eccentricity greater than the first-order relative eccentricity of the multiple heads HD when the head change is performed.

[0156] The magnetic disk device 1 uses the relative eccentric positions (=dprro1[sct]) corresponding to the two heads HD before and after the head change as the AC portion inter-head relative position (or AC portion inter-head relative position correction value) pchg_hd_ac.

[0157] The magnetic disk device 1 adds the DC portion inter-head relative position pchg_hd_dc and the AC portion inter-head relative position pchg_hd_ac to calculate the inter-head relative position pchg_hd. The magnetic disk device 1 adds the inter-head relative position pchg_hd to the estimated position pesti.

[0158] The magnetic disk device 1 corrects the servo partition according to the estimated position of the next sampling when the head is changed. For example, the magnetic disk device 1 determines whether the estimated position of the next sampling of the next head HD after the head change is located in the servo partition in the outer direction or in the servo partition in the inner direction in the radial direction relative to the boundary BD of the servo partition adjacent in the radial direction. The magnetic disk device 1 corrects (or adjusts) the timing of the servo gate corresponding to the servo wedge SvWd (servo region SvR) of the servo partition where the head HD is arranged after the head change according to the determination result.

[0159] Furthermore, the magnetic disk device 1 estimates the RRO position Prro based on the RRO compensation current Ivcm_rro when the head is changed, and calculates the relative speed (hereinafter sometimes referred to as inter-head relative speed) dvrro1 between the current head HD and the next head HD based on the RRO position Prro.

[0160] In addition, the magnetic disk device 1 can also calculate the change of the RRO position by a method of solving the change in the servo track number within one revolution demodulated in a state where the actuator is pressed against the inner circumference stopper, a method of solving the change in the servo track number within one revolution demodulated in a state where the first or higher order wave components of the applied current of the actuator ACT (for example, VCM14) are small in a state where the head is tracking on the disk, or a method of solving the change in the servo track number within one revolution demodulated in a state where the applied current of the actuator ACT (for example, VCM14) is 0 or a constant bias current is passed in one revolution to stop the head at a predetermined radial position on the disk. In addition, the magnetic disk device 1 can also calculate the change of the RRO position based on the change in the interval of the servo wedge SvWd when the disk shift (for example, first order eccentricity) occurs.

[0161] Fig.21 FIG. 1 is a flowchart showing an example of a head change processing method according to the present embodiment. The magnetic disk device 1 executes, for example, a background process. Fig.21 Header change processing shown.

[0162] The disk device 1 receives the interrupt processing of each sample (B2101), determines the head number of the next head HD specified by the command received from the host 100, etc. (B2102), and calculates the head relative position correction value corresponding to the two head HDs before and after the head change (B2103). The disk device 1 corrects the servo partition configured for the next head when the head is changed based on the head relative position correction value (B2104). The disk device 1 performs a head change (B2105). For example, the disk device 1 changes the head from head HD0 to head HD1. The disk device 1 receives the interrupt processing of each sample (B2106), and ends the processing.

[0163] Fig. 22 is a flowchart showing an example of a method for calculating the relative position between heads according to the present embodiment. The magnetic disk device 1 executes, for example, a background process. Fig. 22 The calculation process of the relative position between heads is shown.

[0164] The magnetic disk device 1 calculates the relative position between the heads of the DC part (B2201) and calculates the relative position between the heads of the AC part (B2202). The magnetic disk device 1 calculates the relative position between the heads based on the relative position between the heads of the DC part and the relative position between the heads of the AC part (B2203). For example, the magnetic disk device 1 calculates the relative position between the heads by adding the relative position between the heads of the DC part and the relative position between the heads of the AC part. The magnetic disk device 1 adds the relative position between the heads to the current estimated position corresponding to the current head HD to calculate the next estimated position corresponding to the next head HD (B2204), and ends the processing.

[0165] Fig.23 FIG. 1 is a flowchart showing an example of a method for calculating the relative position between AC part heads according to the present embodiment. The magnetic disk device 1 executes, for example, a background process. Fig.23 The calculation process of the relative position between the AC part heads is shown.

[0166] The disk device 1 specifies the next sector according to the command received from the host 100 or the like (B2301). The disk device 1 refers to an eccentricity table corresponding to the current head HD, for example, a table of eccentricity compensation current values ​​corresponding to the current head HD (B2302). The disk device 1 refers to an eccentricity table corresponding to the next head HD, for example, a table of eccentricity compensation current values ​​corresponding to the next head HD (B2303). The disk device 1 calculates the SIN component and COS component of the DFT coefficient corresponding to the relative position between the two current head HDs and the next head HD before and after the head change (B2304). For example, the disk device 1 calculates the first-order SIN component and the first-order COS component of the DFT coefficient corresponding to the relative position between the two current head HDs and the next head HD before and after the head change. The disk device 1 calculates the relative eccentricity position between the two current head HDs and the next head HD before and after the head change based on the DFT coefficient (B2305). For example, the disk device 1 calculates the relative eccentric position of the two current head HDs and the next head HD before and after the head change. The disk device 1 sets the relative eccentric position of the two current head HDs and the next head HD before and after the head change as the relative position between the AC parts heads (or the relative position correction value between the AC parts heads) (B2306), and ends the processing. For example, the disk device 1 sets the relative eccentric position of the two current head HDs and the next head HD before and after the head change as the relative position between the AC parts heads, and ends the processing.

[0167] Fig.24 is a flowchart showing an example of a servo zone correction processing method according to the present embodiment. The magnetic disk device 1 executes, for example, a background process. Fig.24 Correction processing of the servo partition shown.

[0168] The disk device 1 determines whether the next estimated position is located in the servo partition in the outer direction or in the servo partition in the inner direction relative to the boundary of two servo partitions adjacent in the radial direction (B2401). For example, the disk device 1 determines whether the next estimated position is located on the servo partition SvZn10 side or on the servo partition SvZn11 side relative to the boundary BD1. In the case where it is determined that the next estimated position is located in the servo partition in the outer direction relative to the boundary of the servo partition ("Yes" in B2401), the disk device 1 sets the next estimated position to the servo partition in the outer direction (B2402) and ends the processing. For example, in the case where it is determined that the next estimated position is located on the servo partition SvZn10 side relative to the boundary BD1, the disk device 1 sets the next estimated position to the servo partition SvZn10 and ends the processing.

[0169] When it is determined that the next estimated position is not located in the servo partition in the outer direction relative to the boundary of the servo partitions adjacent in the radial direction, that is, in the servo partition in the inner direction ("No" in B2401), the disk device 1 sets the next estimated position to the servo partition in the inner direction relative to the boundary of the two adjacent servo partitions (B2402), and the processing is terminated. For example, when it is determined that the next estimated position is located on the servo partition SvZn11 side relative to the boundary BD1, the disk device 1 sets the next estimated position to the servo partition SvZn11, and the processing is terminated.

[0170] Fig.25 is a flowchart showing an example of an interrupt processing method for each sample according to the present embodiment. For example, the magnetic disk device 1 executes in the foreground process Fig.25 The interrupt processing for each sample is shown.

[0171] The magnetic disk device 1 obtains the head position by reading the servo sector of the disk DK (B2501). The magnetic disk device 1 calculates the next estimated position (B2502). The magnetic disk device 1 calculates the current indication value (B2503) based on the target acceleration, the target speed, the next estimated position and the RRO current compensation value. The magnetic disk device 1 applies the VCM current to the VCM 14 according to the current indication value (B2504), and the processing ends.

[0172] According to the present embodiment, the magnetic disk device 1 has a plurality of disks DK0 and DK1, and a plurality of heads HD0 and HD1 corresponding to the plurality of disks DK0 and DK1, respectively. After the subsequent disk shift occurs, the magnetic disk device 1 learns the eccentricity of each disk DK0 and DK1, and records the learning result in an eccentricity table. The magnetic disk device 1 calculates the relative position between the heads corresponding to the two heads HD before and after the head change in the next sector specified by the command received from the host 100, etc. The magnetic disk device 1 updates the next estimated position and servo partition based on the relative position between the heads. The magnetic disk device 1 corrects (or adjusts) the servo gate based on the next estimated position and servo partition, and makes the servo gate effective so that the servo wedge SvWd can be read, thereby enabling the servo reading (or demodulation) of the servo wedge SvWd even if the head change is performed after the subsequent disk shift. Even if the disk DK in the overlap region OvR with a wide width in the radial direction has a post-disk shift, the magnetic disk device 1 can change the head to read the servo wedge SvWd. The data format efficiency of the disk DK can be improved. In other words, even if the disk DK in the overlap region OvR has a narrow width, the magnetic disk device 1 can change the head to read the servo wedge SvWd. Therefore, the magnetic disk device 1 can narrow the overlap region OvR, thereby improving the data format efficiency of the disk DK. In addition, the magnetic disk device 1 can improve reliability.

[0173] Several embodiments have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and can be omitted, replaced, and changed in various ways without departing from the scope of the invention. These embodiments and their variations are included in the scope and purpose of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: A first disk divided into a first partition and a second partition by a boundary in a radial direction, comprising a plurality of first servo wedges having a first servo pattern arranged in the first partition and a second servo pattern arranged in the second partition; a second disk divided into the first partition and the second partition by the boundary in the radial direction, including a plurality of second servo wedges having the first servo pattern and the second servo pattern, and having a second center position shifted from the first center position of the first disk; a first head for writing data to the first disk and reading data from the first disk; a second head for writing data to the second disk and reading data from the second disk; as well as a controller that, when switching the first head to the second head, calculates an estimated position at which the second head is arranged on the second disk based on first relative position information associated with the relative positions of the first head and the second head in the radial direction, The controller calculates the first relative position information based on the second relative position information associated with the relative position of the first head and the second head in the radial direction that changes within one week of the first disk and the second disk, and the third relative position information associated with the relative position of the first head and the second head in the radial direction that does not change within one week of the first disk and the second disk.

2. The magnetic disk device according to claim 1, The controller calculates the second relative position information based on first eccentricity information regarding eccentricity in the first disk corresponding to the first head and second eccentricity information regarding eccentricity in the second disk corresponding to the second head.

3. The magnetic disk device according to claim 2, The controller calculates the first discrete Fourier transform coefficient corresponding to the first head based on the first eccentricity information, calculates the second discrete Fourier transform coefficient corresponding to the second head based on the second eccentricity information, and calculates the second relative position information based on the first discrete Fourier transform coefficient and the second discrete Fourier transform coefficient.

4. The magnetic disk device according to any one of claims 1 to 3, The controller calculates the first relative position information at the timing when receiving a command to switch the first head to the second head.

5. The magnetic disk device according to any one of claims 1 to 3, The boundary is located in a region where the first servo pattern and the second servo pattern are arranged in a circumferential direction.

6. A magnetic disk device comprising: A first disk divided into a first partition and a second partition by a boundary in a radial direction, comprising a plurality of first servo wedges having a first servo pattern arranged in the first partition and a second servo pattern arranged in the second partition; a second disk divided into the first partition and the second partition by the boundary in the radial direction, including a plurality of second servo wedges having the first servo pattern and the second servo pattern, and having a second center position shifted from the first center position of the first disk; a first head for writing data to the first disk and reading data from the first disk; a second head for writing data to the second disk and reading data from the second disk; as well as a controller that, when switching the first head to the second head, calculates an estimated position at which the second head is arranged on the second disk based on first relative position information associated with the relative positions of the first head and the second head in the radial direction, When the controller switches the first head located in the first partition to the second head, the controller determines whether the second head is located in the first partition or the second partition based on the boundary.

7. The magnetic disk device according to claim 6, The controller determines that the second head is located in the first partition when the estimated position is located in the first direction on the first partition side relative to the boundary, and determines that the second head is located in the second partition when the estimated position is located on the second partition side relative to the boundary.

8. The magnetic disk device according to claim 7, The controller sets the second head to the second partition when determining that the second head is located in the second partition.

9. The magnetic disk device according to claim 8, The controller enables a servo gate so that the second head reads the first servo pattern.

10. A head change processing method, applied to a magnetic disk device, the magnetic disk device comprising: a first disk divided into a first partition and a second partition by a boundary in a radial direction, including a plurality of first servo wedges having a first servo pattern arranged in the first partition and a second servo pattern arranged in the second partition; a second disk divided into the first partition and the second partition by the boundary in the radial direction, including a plurality of second servo wedges having the first servo pattern and the second servo pattern, and having a second center position shifted from a first center position of the first disk; a first head that writes data to the first disk and reads data from the first disk; and a second head that writes data to the second disk and reads data from the second disk. In the head change processing method, when the first head is switched to the second head, an estimated position at which the second head is configured on the second disk is calculated based on first relative position information associated with the relative positions of the first head and the second head in the radial direction, The first relative position information is calculated based on the second relative position information associated with the relative position of the first head and the second head in the radial direction that changes within one week of the first disk and the second disk, and the third relative position information associated with the relative position of the first head and the second head in the radial direction that does not change within one week of the first disk and the second disk.

11. A head change processing method, applied to a magnetic disk device, the magnetic disk device comprising: a first disk divided into a first partition and a second partition by a boundary in a radial direction, including a plurality of first servo wedges having a first servo pattern arranged in the first partition and a second servo pattern arranged in the second partition; a second disk divided into the first partition and the second partition by the boundary in the radial direction, including a plurality of second servo wedges having the first servo pattern and the second servo pattern, and having a second center position shifted from a first center position of the first disk; a first head that writes data to the first disk and reads data from the first disk; and a second head that writes data to the second disk and reads data from the second disk. In the head change processing method, when the first head is switched to the second head, an estimated position at which the second head is configured on the second disk is calculated based on first relative position information associated with the relative positions of the first head and the second head in the radial direction, When the first head located in the first partition is switched to the second head, it is determined based on the boundary whether the second head is located in the first partition or the second partition.

Images