Disk devices and SSW method

Abstract

This disclosure provides a disk device and a SSW method that can improve reliability. The disk device according to this embodiment includes: a disk having a first surface and a second surface different from the first surface; a first head for reading and writing data on the first surface; a second head for reading and writing data on the second surface; and a controller that adjusts the helical speed of the write helical servo pattern of at least one of the first head and the second head according to a cylindrical offset amount corresponding to the deviation between the first head and the second head.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2021-210904 (filed on December 24, 2021). This application incorporates the entire contents of that basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to disk devices and SSW methods. Background Technology

[0003] In the Blank Disk Write (BDW) process of writing spiral servo patterns, the disk device writes multiple spiral servo patterns (hereinafter, sometimes called reference spiral servo patterns) onto one side of the disk (hereinafter, sometimes called the reference side) which has no data or patterns written on it, using a head (hereinafter, sometimes called the reference head) corresponding to that reference side. The disk device 1, based on the reference spiral servo patterns, writes multiple servo patterns (hereinafter, sometimes called product servo patterns) to the reference side using the reference head on the reference side. In the Self Servo Write (SSW) process, the disk device, based on the reference spiral servo patterns written to the reference side using the reference head, writes or copies multiple spiral servo patterns (hereinafter, sometimes called copied spiral servo patterns) to a side (hereinafter, sometimes called other sides) different from the reference side using a different head (hereinafter, sometimes called other heads). When the reference head and other heads are positioned at the same radius of the disk, such as a cylinder, due to construction errors, the reference head and other heads may not be configured at the same radius, such as a cylinder. In other words, the reference head and other heads may not face each other across the disk, but may be offset in the radial direction of the disk. Due to the deviation or error between the reference head and other heads (hereinafter, sometimes referred to as cylindrical offset), a deviation may occur between the reference spiral servo pattern and the replicated spiral servo pattern. Summary of the Invention

[0004] The problem to be solved by the embodiments of the present invention is to provide a disk drive device and SSW method that can improve reliability.

[0005] The disk device according to this embodiment includes: a disk having a first surface and a second surface different from the first surface; a first head for reading and writing data on the first surface; a second head for reading and writing data on the second surface; and a controller for adjusting the spiral speed of the write spiral servo pattern of at least one of the first head and the second head according to a cylindrical offset amount corresponding to the deviation between the first head and the second head. Attached Figure Description

[0006] Figure 1 This is a block diagram illustrating the structure of the disk device involved in the implementation method.

[0007] Figure 2 This is a schematic diagram illustrating an example of the head's configuration relative to the disk in an embodiment.

[0008] Figure 3 This is a cross-sectional view schematically illustrating a structural example of multiple disks and multiple heads involved in an embodiment.

[0009] Figure 4 This is a top view schematically illustrating an example of a servo pattern related to an implementation method.

[0010] Figure 5 This is a schematic diagram illustrating an example of a head amplifier IC involved in an implementation.

[0011] Figure 6 This is a schematic diagram illustrating an example of the correspondence between the reference head and the spiral copy head.

[0012] Figure 7 This is a schematic diagram illustrating an example of a reference spiral servo pattern.

[0013] Figure 8 This is a schematic diagram illustrating an example of replicating a spiral servo pattern.

[0014] Figure 9 This is a schematic diagram illustrating an example of how a gray code number changes relative to a radius.

[0015] Figure 10 This is a schematic diagram illustrating an example of the change in cylindrical offset relative to the radius position compared to the reference head in the implementation method.

[0016] Figure 11 This is a schematic diagram illustrating an example of the change in cylindrical offset relative to the radius position compared to a predetermined head in an embodiment.

[0017] Figure 12 This is a schematic diagram illustrating an example of the SSW processing involved in the implementation method.

[0018] Figure 13 This is a schematic diagram illustrating an example of the SSW processing involved in Variation Example 1.

[0019] Label Explanation

[0020] 1…Disk device, 10…Disk, 10a…User data area, 10b…System area, 12…Spindle motor (SPM), 13…Arm, 14…Voice coil motor (VCM), 15…Head, 15W…Write head, 15R…Read head, 20…Driver IC, 30…Head amplifier IC, 40…Read / write (R / W) channel, 50…Hard disk controller (HDC), 60…Microprocessor (MPU), 70…Volatile memory, 80…Non-volatile memory, 90…Buffer memory, 100…Host system (host), 130…System controller. Detailed Implementation

[0021] The embodiments will now be described with reference to the accompanying drawings. Furthermore, the drawings are merely examples and do not limit the scope of the invention.

[0022] (Implementation Method)

[0023] Figure 1 This is a block diagram illustrating the structure of the disk device 1 according to the embodiment.

[0024] The disk drive 1 includes: a head disk assembly (HDA) as described later, a driver IC 20, a head amplifier integrated circuit (hereinafter, head amplifier IC or preamplifier) ​​30, volatile memory 70, non-volatile memory 80, buffer memory (cache) 90, and a system controller 130 as a single-chip integrated circuit. Furthermore, the disk drive 1 is connected to a host system (hereinafter simply referred to as the host) 100.

[0025] The HDA includes a disk (hereinafter referred to as a disk) 10, a spindle motor (hereinafter referred to as a SPM) 12, an arm 13 with a head 15 mounted on it, and a voice coil motor (hereinafter referred to as a VCM) 14. The disk 10 is mounted on the SPM 12 and rotates by the drive of the SPM 12. The arm 13 and the VCM 14 constitute an actuator. The actuator, driven by the VCM 14, controls the head 15 mounted on the arm 13 to move it to a predetermined position on the disk 10. Multiple disks 10 and heads 15 are provided. Alternatively, only one disk 10 and one head 15 may be provided.

[0026] Disk 10 has a user data area 10a available to users and a system area 10b for writing information required for system management, allocated within its writable data area. Additionally, disk 10 may also have a media cache (sometimes called a media cache area) allocated as a separate area from the user data area 10a and system area 10b, for temporarily storing or recording data (or commands) transmitted from the host 100, etc., before it is written to a predetermined area of ​​the user data area 10a. Hereinafter, the direction from the inner periphery of disk 10 towards the outer periphery, or from the outer periphery of disk 10 towards the inner periphery, is referred to as the radial direction. Within the radial direction, the direction from the inner periphery towards the outer periphery is called the outer direction (outer side), and the direction from the outer periphery towards the inner periphery is called the inner direction (inner side). A direction that intersects, for example, the radial direction of disk 10 orthogonal to it is called the circumferential direction. The circumferential direction corresponds to the direction along the circumference of disk 10. Furthermore, a predetermined position in the radial direction of disk 10 is sometimes called the radial position, and a predetermined position in the circumferential direction of disk 10 is sometimes called the circumferential position. Sometimes, the radial position and the circumferential position are collectively referred to as the position. Disk 10 is divided into multiple zones (hereinafter sometimes referred to as zones or zone areas) along predetermined ranges in the radial direction. A zone includes multiple tracks. A track includes multiple sectors. Furthermore, the term "track" is used in various senses, such as "one of the multiple zones obtained by dividing disk 10 into predetermined ranges in the radial direction," "data written to one of the multiple zones obtained by dividing disk 10 into predetermined ranges in the radial direction," "a region extending circumferentially at a predetermined radius position of disk 10," "data written to a region extending circumferentially at a predetermined radius position of disk 10," "a region around a predetermined radius position of disk 10," "data written around a predetermined radius position of disk 10," "the path of the head 15 located at a predetermined radius position of disk 10," "data written through the head 15 located at a predetermined radius position of disk 10," "data written to a predetermined track of disk 10," and other various meanings. The term "sector" has various meanings, such as "one region among multiple regions obtained by dividing disk 10 into predetermined tracks in the circumferential direction," "data written to one region among multiple regions obtained by dividing disk 10 into predetermined tracks in the circumferential direction," "a region at a predetermined circumferential position at a predetermined radius of disk 10," "data written to a region at a predetermined circumferential position at a predetermined radius of disk 10," "data written to a predetermined sector of disk 10," and so on. Sometimes, the "width of the track in the radial direction" is also referred to as "track width." Sometimes, the center position of the track width is also referred to as the track center. Sometimes, the track center is simply referred to as the track.

[0027] Head 15 faces disk 10. For example, one head 15 faces one face of disk 10. Head 15 has a slider as its main body and includes a write head 15W and a read head 15R mounted on the slider. Write head 15W writes data to disk 10. Read head 15R reads the data written to disk 10. Sometimes, "write head 15W" is simply referred to as "head 15," sometimes "read head 15R" is simply referred to as "head 15," and sometimes both "write head 15W" and "read head 15R" are collectively referred to as "head 15." Sometimes, the "center portion of head 15" is referred to as "head 15," the "center portion of write head 15W" is referred to as "write head 15W," and the "center portion of read head 15R" is referred to as "read head 15R." Sometimes, the "center portion of write head 15W" is simply referred to as "head 15," and sometimes the "center portion of read head 15R" is simply referred to as "head 15." Sometimes, "positioning the center of the head 15 in the center of the predetermined track" is expressed as "positioning the head 15 in the predetermined track", "arranging the head 15 in the predetermined track", or "positioning the head 15 in the predetermined track".

[0028] Figure 2 This is a schematic diagram illustrating an example of the configuration of the head 15 relative to the disk 10 according to this embodiment. Figure 2 The image shows the innermost IMC and outermost OMC of disk 10. (Example) Figure 2 As shown, the direction in which disk 10 rotates in the circumferential direction is called the rotation direction. Furthermore, in... Figure 2 In the example shown, the rotation direction is indicated as counterclockwise, but it can also be the opposite (clockwise). The height direction Z is parallel to the direction in which the spindle SP of the SPM12 extends. In other words, the height direction Z is the direction in which the multiple disks 10 are stacked. Furthermore, the height direction Z corresponds to the direction from the bottom wall of the disk drive 1 towards the cover opposite to the bottom wall. In the height direction Z, the direction from disk 10-n towards disk 10-m is sometimes referred to as the upper side (or simply upper), and the direction from disk 10-m towards disk 10-n is sometimes referred to as the lower side (or simply lower). Additionally, assuming there is a viewing position for observing the disk drive 1 at the tip of the arrow representing the height direction Z, the view from that viewing position towards the surface of the disk 10 is sometimes referred to as a top view.

[0029] exist Figure 2 In the example shown, the SPM12 has a spindle SP. The spindle SP extends in the height direction Z. The spindle SP can rotate about the central axis SPC.

[0030] Disk 10 includes multiple disks 10. In Figure 2In the example shown, disk 10 includes disk 10-m, disk 10-n, ..., where m ≥ 0 and n > m (n ≥ 0). Furthermore, disk 10 can include three or more disks, or it can include only one disk. Disk 10 is mounted on spindle SP. Disk 10 has surfaces 10S (10S(2m), 10S(2m+1), 10S(2n), 10S(2n+1), ...). Surfaces 10S (10S(2m), 10S(2m+1), 10S(2n), 10S(2n+1), ...) extend parallel to a plane extending in a direction perpendicular to the height direction Z. Furthermore, surfaces 10S (10S(2m), 10S(2m+1), 10S(2n), 10S(2n+1), ...) can also extend parallel to a plane inclined relative to the plane extending in a direction perpendicular to the height direction Z. Disk 10-m has a surface 10S(2m) and a back surface 10S(2m+1) opposite to the surface 10S(2m). Surface 10S(2m) is the side facing upward in the height direction Z. Back surface 10S(2m+1) is the side facing downward in the height direction Z. Back surface 10S(2m+1) is located below surface 10S(2m). Disk 10-n has a surface 10S(2n) and a back surface 10S(2n+1) opposite to the surface 10S(2n). Surface 10S(2n) is the side facing upward in the height direction Z. Back surface 10S(2n+1) is the side facing downward in the height direction Z. Back surface 10S(2n+1) is located below surface 10S(2n). Disk 10-n is located below disk 10-m in the height direction Z. In other words, disk 10-n is located below disk 10-m in the height direction Z. Viewed from above, disks 10-m and 10-n overlap. Surface 10S(2m) has user data area 10a(2m) and system area 10b(2m). Rear side 10S(2m+1) has user data area 10a(2m+1) and system area 10b(2m+1). Surface 10S(2n) has user data area 10a(2n) and system area 10b(2n). Rear side 10S(2n+1) has user data area 10a(2n+1) and system area 10b(2n+1).

[0031] Head 15 includes multiple Head 15s. In Figure 2 In the example shown, head 15 includes head 15-2m, head 15-(2m+1), head 15-2n, head 15-(2n+1)... Furthermore, head 15 can include either more than five heads 15 or fewer heads 15. Figure 2 In the example shown, multiple heads 15 are disposed on the same actuator. Alternatively, the multiple heads 15 may not be disposed on the same actuator. The heads 15 face the surface 10S. Each of the multiple heads 15 faces the surface 10S of the multiple disks 10. Figure 2In the example shown, head 15-2m faces surface 10S(2m). Head 15-2m writes data to surface 10S(2m) and reads data from surface 10S(2m). Head 15-(2m+1) faces back surface 10S(2m+1). Head 15-(2m+1) writes data to back surface 10S(2m+1) and reads data from back surface 10S(2m+1). Head 15-2n faces surface 10S(2n). Head 15-2n writes data to surface 10S(2n) and reads data from surface 10S(2n). Head 15-(2n+1) faces back surface 10S(2n+1). Head 15-(2n+1) writes data to back surface 10S(2n+1) and reads data from back surface 10S(2n+1).

[0032] Figure 3 This is a cross-sectional view schematically illustrating a structural example of the plurality of disks 10 and the plurality of heads 15 involved in this embodiment. Figure 3 and Figure 2 correspond.

[0033] exist Figure 3 In the example shown, when heads 15-2m and 15-(2m+1) are positioned at a predetermined radius, they are offset from each other in the radial direction by an error of CyOm. In other words, heads 15-2m and 15-(2m+1) are offset from each other in the radial direction by an error of CyOm when positioned on a predetermined cylindrical surface. That is, heads 15-2m and 15-2(m+1) are not facing each other with a distance of 10-m between them.

[0034] When heads 15-2m, 15-2n, and 15-(2n+1) are positioned at a predetermined radius, they are offset from each other in the radial direction. In other words, when heads 15-2m, 15-2n, and 15-(2n+1) are positioned on a predetermined cylindrical surface, they are offset in the radial direction. That is, heads 15-2m, 15-2n, and 15-(2n+1) are not oriented relative to each other in a manner that sandwiches the multiple disks 10 in the middle.

[0035] Furthermore, heads 15-(2m+1), 15-2n, and 15-(2n+1) are offset from each other in the radial direction when positioned at a predetermined radius. In other words, heads 15-(2m+1), 15-2n, and 15-(2n+1) are offset in the radial direction when positioned on a predetermined cylindrical surface. That is, heads 15-(2m+1), 15-2n, and 15-(2n+1) are not oriented relative to each other in a manner that sandwiches the multiple disks 10 in the middle.

[0036] exist Figure 3In the example shown, when heads 15-2n and 15-(2n+1) are positioned at a predetermined radius, they are offset from each other in the radial direction by an error CyOn. In other words, when heads 15-2n and 15-(2n+1) are positioned on a predetermined cylindrical surface, they are offset in the radial direction by an error CyOm. That is, heads 15-2m and 15-2(m+1) are not facing each other with a distance of 10-m between them.

[0037] When heads 15-2n, 15-2m, and 15-(2m+1) are positioned at a predetermined radius, they are offset from each other in the radial direction. In other words, when heads 15-2n, 15-2m, and 15-(2m+1) are positioned on a predetermined cylindrical surface, they are offset in the radial direction. That is, heads 15-2n, 15-2m, and 15-(2m+1) are not oriented relative to each other in a manner that sandwiches the multiple disks 10 in the middle.

[0038] Furthermore, heads 15-(2n+1), 15-2m, and 15-(2m+1) are offset from each other in the radial direction when positioned at a predetermined radius. In other words, heads 15-(2n+1), 15-2m, and 15-(2m+1) are offset in the radial direction when positioned on a predetermined cylindrical surface. That is, heads 15-(2n+1), 15-2m, and 15-(2m+1) are not oriented relative to each other in a manner that sandwiches the multiple disks 10 in the middle.

[0039] like Figure 3 As shown, the relative deviation or error in the radial direction of multiple data entries written when multiple heads 15 are positioned at the same radius location, such as the same cylinder (track), or two data entries in multiple tracks or sectors, such as two tracks or two sectors, is sometimes referred to as cylinder offset or cylinder offset amount. Additionally, the relative deviation or error in the radial direction between two heads 15 when multiple heads 15 are positioned at the same radius location is sometimes referred to as cylinder offset or cylinder offset amount.

[0040] Figure 4 This is a top view schematically illustrating an example of a servo pattern involved in this embodiment. Figure 4 The figure shows the amount of deviation (hereinafter, sometimes referred to as read / write (R / W) offset) OFrw in the radial direction of the write head 15W and read head 15R, which are positioned at a predetermined skew angle.

[0041] The surface 10S of disk 10 has multiple servo patterns (hereinafter, sometimes referred to as product servo patterns) or multiple servo areas (hereinafter, sometimes referred to as product servo areas) PSV used in the final product, and multiple spiral servo patterns (multiple coarse spiral (CGS) servo patterns, multiple final spiral (FS) servo patterns, multiple fine spiral (FGS) servo patterns and multiple final spiral (FS) servo patterns BSV, which are different from the multiple product servo patterns.

[0042] exist Figure 4 For convenience, multiple spiral servo patterns (BSVs) extend spirally on the surface 10S of disk 10. Although described as multiple spiral servo patterns (BSVs) extending in parallel on the surface 10S of disk 10, they may actually extend non-parallel. The multiple spiral servo patterns (BSVs) are discretely arranged at predetermined intervals along the circumference of disk 10. Hereinafter, the "spiral servo pattern (BSV) on a predetermined track" is sometimes referred to as a "spiral servo sector." Furthermore, the "spiral servo pattern (BSV)" is sometimes referred to as a "spiral servo sector." The "spiral servo sector" is sometimes referred to as a "spiral servo pattern." The "spiral servo sector" contains corresponding "servo data." Furthermore, the "spiral servo data written to the spiral servo sector" is sometimes referred to as a "spiral servo sector" or a "spiral servo pattern." Additionally, the "servo data" is sometimes referred to as a "servo sector" or a "servo pattern."

[0043] exist Figure 4 For convenience, multiple product servo patterns (PSVs) extend linearly in the radial direction. Furthermore, although described as multiple product servo patterns (PSVs) extending linearly from the inside to the outside in the radial direction, they may also be curved. For example, the product servo patterns (PSVs) may also extend spirally on the surface 10S of the disk 10. Multiple product servo patterns (PSVs) extend radially in the radial direction of the disk 10 and are discretely arranged at predetermined intervals in the circumferential direction of the disk 10. Hereinafter, "product servo patterns (PSVs) on predetermined tracks" are sometimes referred to as "product servo sectors." Also, "product servo patterns (PSVs)" are sometimes referred to as "product servo sectors." "Product servo sectors" are sometimes referred to as "product servo patterns." "Product servo sectors" contain "servo data." Furthermore, "product servo data written to product servo sectors" is sometimes referred to as "product servo sectors." Additionally, "data other than product servo data written to user data areas 10a outside of product servo sectors" is sometimes referred to as "user data."

[0044] A servo sector (or servo data) may include, for example, a preamble, a servo mark, a Gray code, a PAD, burst data (string data), and a postcode. Alternatively, a servo sector (or servo data) may not include a postcode. A servo sector (or servo data) may also be configured to include at least one of the following: preamble, servo mark, Gray code, PAD, burst data, and postcode. Furthermore, a servo sector (or servo data) may also consist of data other than the preamble, servo mark, Gray code, PAD, burst data, and postcode. Within a servo sector, the preamble, servo mark, Gray code, PAD, burst data, and postcode are arranged consecutively from front to back in the circumferential direction, as described above. The preamble includes preamble information composed of the servo mark and Gray code, used for synchronization with the reproduction signal of the servo pattern. The servo mark includes servo mark information indicating the start of the servo pattern. Gray code consists of the address of a predetermined track (cylinder address) and the address of the servo sector of the predetermined track. Burst data is data (relative position data) used to detect the position deviation (position error) of head 15 relative to the center of the predetermined track in the radial and / or circumferential directions, and consists of a repeating pattern of predetermined periods. PAD includes PAD information such as gap and servo AGC synchronization signals. Burst data is written in a data pattern in which the phase of the burst data is reversed by 180° in the radial direction of disk 10 by one servo track cycle. The servo track (servo cylinder) corresponds to the track that is the object of write or read processing according to commands from host 100, etc. Burst data is used to obtain, for example, the position of head 15 in the radial and / or circumferential directions on disk 10 (hereinafter, sometimes referred to as head position). Burst data includes, for example, N-burst and Q-burst. N-burst and Q-burst are written in a data pattern with a phase deviation of 90° from each other in the radial direction of disk 10. The postcode includes data for correcting errors (hereinafter, sometimes referred to as RRO correction data), which are caused by the skew of the track relative to the path (hereinafter, sometimes referred to as the target path) of the head 15, configured concentrically with the disk 10, caused by the wobbling (repetitive yaw: RRO) synchronized with the rotation of the disk 10 when servo data is written to the disk. For ease of explanation, the error caused by the skew of the track relative to the target path due to RRO will sometimes be simply referred to as RRO.

[0045] The driver IC20 is connected to the system controller 130 (specifically, the MPU60 described later), SPM12, and VCM14, and controls the driving of SPM12 and VCM14 according to the control of the system controller 130 (specifically, the MPU60 described later).

[0046] The head amplifier IC 30 may include one or more head amplifier ICs 30. The head amplifier IC (preamplifier) ​​30 includes a read amplifier (not shown) and a write driver. The read amplifier amplifies the read signal read from disk 10 and outputs it to the system controller 130 (specifically, the read / write (R / W) channel 40 described later). The write driver outputs a write current corresponding to the signal output from the R / W channel 40 to the head 15. The head amplifier IC 30 is electrically connected to the head 15, etc.

[0047] Figure 5 This is a schematic diagram illustrating an example of the head amplifier IC30 according to this embodiment. Figure 5 In this configuration, head amplifier IC30 includes head amplifier ICs 301 and 302. Figure 5In this configuration, disk 10 includes disks 10-(m-2), 10-(m-1), 10-m, 10-(m+1), 10-(m+2), 10-(n-2), 10-(n-1), 10-n, 10-(n+1), and 10-(n+2), ... Furthermore, disk 10 can include disks 10 with 11 or more disks, or disks 10 with 9 or fewer disks. Disk 10-(m-2) has a surface 10S(2m-4) and a back surface 10S(2m-3) opposite to the surface 10S(2m-4). The back surface 10S(2m-3) is located below the surface 10S(2m-4). Disk 10-(m-1) has a surface 10S(2m-2) and a back surface 10S(2m-1) opposite to the surface 10S(2m-2). The back face 10S(2m-1) is located below the surface 10S(2m-2). Disk 10-m has a back face 10S(2m+1) opposite to the surface 10S(2m). The back face 10S(2m+1) is located below the surface 10S(2m). Disk 10-(m+1) has a back face 10S(2m+3) opposite to the surface 10S(2m+2). The back face 10S(2m+3) is located below the surface 10S(2m+2). Disk 10-(m+2) has a surface 10S(2m+4). Surface 10S(2m+4) is the upward-facing surface. Disk 10-(n-2) has a back face 10S(2n-3) opposite to the surface 10S(2n-4). The back side 10S(2n-3) is located below the surface 10S(2n-4). Disk 10-(n-1) has a back side 10S(2n-1) opposite to the surface 10S(2n-2). The back side 10S(2n-1) is located below the surface 10S(2n-2). Disk 10-n has a back side 10S(2n+1) opposite to the surface 10S(2n). The back side 10S(2n+1) is located below the surface 10S(2n). Disk 10-(n+1) has a back side 10S(2n+3) opposite to the surface 10S(2n+2). The back side 10S(2n+3) is located below the surface 10S(2n+2). Disk 10-(n+2) has surface 10S(2n+4). Surface 10S(2n+4) is the upward-facing face.

[0048] exist Figure 5In this context, the head 15 includes head 15-(2m-4), 15-(2m-3), 15-(2m-2), 15-(2m-1), 15-(2m), 15-(2m+1), 15-(2m+2), 15-(2m+3), 15-(2m+4), 15-(2n-4), 15-(2n-3), 15-(2n-2), 15-(2n-1), 15-(2n), 15-(2n+1), 15-(2n+2), 15-(2n+3), and 15-(2n+4), ... Furthermore, the head 15 can include either 11 or more head 15s, or 9 or fewer head 15s. Figure 5 In this configuration, multiple heads 15 (15-(2m-4)~15-(2m+4), 15-(2n-4)~15-(2n+4)) are mounted on the same actuator. Alternatively, multiple heads 15 (15-(2m-4)~15-(2m+4), 15-(2n-4)~15-(2n+4)) may not be mounted on the same actuator. Figure 5In the example shown, head 15-(2m-4) faces surface 10S(2m-4). Head 15-(2m-4) writes data to surface 10S(2m-4) and reads data from surface 10S(2m-4). Head 15-(2m-3) faces surface 10S(2m-3). Head 15-(2m-3) writes data to surface 10S(2m-3) and reads data from surface 10S(2m-3). Head 15-(2m-2) faces surface 10S(2m-2). Head 15-(2m-2) writes data to surface 10S(2m-2) and reads data from surface 10S(2m-2). Head 15-(2m-1) faces surface 10S(2m-1). Head 15-(2m-1) writes data to surface 10S(2m-1) and reads data from surface 10S(2m-1). Head 15-(2m) is opposite to surface 10S(2m). Head 15-(2m) writes data to surface 10S(2m) and reads data from surface 10S(2m). Head 15-(2m+1) is opposite to surface 10S(2m+1). Head 15-(2m+1) writes data to surface 10S(2m+1) and reads data from surface 10S(2m+1). Head 15-(2m+2) is opposite to surface 10S(2m+2). Head 15-(2m+2) writes data to surface 10S(2m+2) and reads data from surface 10S(2m+2). Head 15-(2m+3) is opposite to surface 10S(2m+3). Head 15-(2m+3) writes data to surface 10S(2m+3) and reads data from surface 10S(2m+3). Head 15-(2m+4) is opposite to surface 10S(2m+4). Head 15-(2m+4) writes data to surface 10S(2m+4) and reads data from surface 10S(2m+4). Head 15-(2n-4) is opposite to surface 10S(2n-4). Head 15-(2n-4) writes data to surface 10S(2n-4) and reads data from surface 10S(2n-4). Head 15-(2n-3) is opposite to surface 10S(2n-3). Head 15-(2n-3) writes data to surface 10S(2n-3) and reads data from surface 10S(2n-3). Head 15-(2n-2) is opposite to surface 10S(2n-2). Head 15-(2n-2) writes data to surface 10S(2n-2) and reads data from surface 10S(2n-2). Head 15-(2n-1) is opposite to surface 10S(2n-1). Head 15-(2n-1) writes data to surface 10S(2n-1) and reads data from surface 10S(2n-1). Head 15-(2n) is opposite to surface 10S(2n). Head 15-(2n) writes data to surface 10S(2n) and reads data from surface 10S(2n). Head 15-(2n+1) is opposite to surface 10S(2n+1).Head 15-(2n+1) writes data to surface 10S(2n+1) and reads data from surface 10S(2n+1). Head 15-(2n+2) is opposite to surface 10S(2n+2). Head 15-(2n+2) writes data to surface 10S(2n+2) and reads data from surface 10S(2n+2). Head 15-(2n+3) is opposite to surface 10S(2n+3). Head 15-(2n+3) writes data to surface 10S(2n+3) and reads data from surface 10S(2n+3). Head 15-(2n+4) is opposite to surface 10S(2n+4). Head 15-(2n+4) writes data to surface 10S(2n+4) and reads data from surface 10S(2n+4).

[0049] exist Figure 5 In the example shown, head amplifier IC301 is electrically connected to head 15-(2m-4) to 15-(2m+4). Head amplifier IC301 is also electrically connected to R / W channel 40 and HDC50.

[0050] exist Figure 5 In the example shown, head amplifier IC302 is electrically connected to head 15-(2n-4) to 15-(2n+4). Head amplifier IC302 is also electrically connected to R / W channel 40 and HDC50.

[0051] The volatile memory 70 is a semiconductor memory whose stored data will be lost if the power supply is cut off. The volatile memory 70 stores data required for processing in various parts of the disk drive 1. The volatile memory 70 is, for example, DRAM (Dynamic Random Access Memory) or SDRAM (Synchronous Dynamic Random Access Memory). In addition, the volatile memory 70 may also be included in the system controller 130 described later.

[0052] The non-volatile memory 80 is a semiconductor memory that records stored data even when the power supply is cut off. The non-volatile memory 80 is, for example, a NOR or NAND flash ROM (Flash Read Only Memory). In addition, the non-volatile memory 80 may also be included in the system controller 130 described later.

[0053] The buffer memory 90 is a semiconductor memory that temporarily records data transmitted and received between the disk drive 1 and the host computer 100. Furthermore, the buffer memory 90 may be integrated with the volatile memory 70. The buffer memory 90 may be, for example, DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), or MRAM (Magnetoresistive Random Access Memory). Additionally, the buffer memory 90 may also be included in the system controller 130, which will be described later.

[0054] The system controller (controller) 130 is implemented using a large-scale integrated circuit (LSI) called a system-on-a-chip (SoC), which integrates multiple components onto a single chip. The system controller 130 includes a read / write (R / W) channel 40, a hard disk controller (HDC) 50, and a microprocessor (MPU) 60. The R / W channel 40, HDC 50, and MPU 60 are each electrically connected to each other. The system controller 130 is electrically connected, for example, to a driver IC 20, a head amplifier IC 60, volatile memory 70, non-volatile memory 80, buffer memory 90, and a host system 100.

[0055] R / W channel 40 performs signal processing on data transferred from disk 10 to host 100, such as read data, and data transferred from host 100, such as write data, according to instructions from MPU 60 (described later). R / W channel 40 is electrically connected to, for example, head amplifier IC 30, HDC 50, and MPU 60. R / W channel 40 has circuitry or functions for modulating write data. Additionally, R / W channel 40 has circuitry or functions for measuring the signal quality of read data and for decoding read data. R / W channel 40 is electrically connected to head amplifier IC 30, etc.

[0056] HDC50 controls the data transfer between host 100 and R / W channel 40 according to instructions from MPU60 (described later). HDC50 is electrically connected, for example, to head amplifier IC30, R / W channel 40, MPU60, volatile memory 70, non-volatile memory 80, and buffer memory 90.

[0057] MPU60 is the main controller that controls all parts of disk drive 1. MPU60 controls VCM14 via driver IC20 to perform servo control for positioning head 15. MPU60 controls data writing operations to disk 10, selecting the data transferred from host 100, such as the destination for writing data. MPU60 controls data reading operations from disk 10 and controls data transfer from disk 10 to host 100, such as data reading processing. Additionally, MPU60 manages the area for recording data. MPU60 is connected to various parts of disk drive 1. MPU60 is electrically connected to, for example, driver IC20, R / W channel 40, and HDC50.

[0058] The MPU60 includes a read / write control unit 610, a servo pattern control unit 620, a cylinder offset measurement unit 630, a spiral copy control unit 640, and a positioning control unit 650. The MPU60 executes the processing of these units, such as the read / write control unit 610, the servo pattern control unit 620, the cylinder offset measurement unit 630, the spiral copy control unit 640, and the positioning control unit 650, in its firmware. Alternatively, the MPU60 can also be configured as a circuit, incorporating these units, such as the read / write control unit 610, the servo pattern control unit 620, the cylinder offset measurement unit 630, the spiral copy control unit 640, and the positioning control unit 650.

[0059] The read / write control unit 610 controls data read and write processes based on commands from the host 100. The read / write control unit 610 controls the VCM 14 via the driver IC 20 to position the head 15 at a predetermined radius position on the disk 10, performing read or write processes. Hereinafter, the terms "access" or "access processing" will sometimes be used to broadly refer to "write processing" and "read processing."

[0060] The servo pattern control unit 620 writes servo patterns to the steering wheel 10. The servo pattern control unit 620 writes the spiral servo pattern BSV and the product servo pattern PSV to the steering wheel 10.

[0061] The servo pattern control unit 620 writes a spiral servo pattern BSV to the disk 10. In the process of writing the spiral servo pattern BSV sequentially to the disk 10, which is a disk write (BDW) (or blank disk servo write) where no data or pattern has been written (hereinafter, sometimes referred to as a blank state), the servo pattern control unit 620 writes the spiral servo pattern BSV to the disk 10. In the BDW process, since data or patterns cannot be read from the blank disk 10, the servo pattern control unit 620 does not perform read processing (or is on track). It uses the position of the disk 10 (hereinafter sometimes referred to as the clock reference position) that corresponds to the reference clock once per cycle as the starting point. Based on the speed information of the head 15 relative to the disk 10 (hereinafter sometimes referred to as the back EMF speed information) generated from the VCM 14, it controls the head 15 at a constant speed to write a spiral servo pattern BSV onto the disk 10 from the inner direction in the radial direction, for example, from the innermost IMC to the outer direction, for example, from the outermost OMC. Alternatively, in the BDW process, the servo pattern control unit 620 can also use the clock reference position of the blank disk 10 as the starting point and control the head 15 at a constant speed based on the back EMF speed information to write a spiral servo pattern BSV onto the disk 10 from the outer direction in the radial direction, for example, from the outermost OMC to the inner direction, for example, from the innermost IMC. The servo pattern control unit 620 writes a spiral servo pattern BSV while accelerating the head 15 to a predetermined speed within a range from the start position (clock reference position) of the blank disk 10 to a predetermined position. Conversely, it writes the spiral servo pattern BSV while decelerating the head from a predetermined speed to a predetermined speed within a range from the predetermined position to the end position of the blank disk 10. Hereinafter, the state of accelerating the head 15 to a predetermined speed within the range from the start position to the predetermined position is sometimes referred to as acceleration state, acceleration time, acceleration control, or acceleration control; the state of writing with the head 15 at a constant speed is sometimes referred to as constant speed state, constant speed time, constant speed control, or constant speed control; and the state of decelerating the head 15 to a predetermined speed within the range from the predetermined position to the end position is sometimes referred to as deceleration state, deceleration time, or deceleration control. Furthermore, the "speed at which the head 15 writes the spiral servo pattern at constant speed" is sometimes referred to as the "spiral speed."

[0062] In the BDW process, the servo pattern control unit 620 writes a spiral servo pattern (hereinafter, sometimes also called a reference spiral servo pattern) BSV onto the surface (hereinafter, sometimes also called a reference surface) 10S of the disk 10 corresponding to the reference head 15 using at least one of a plurality of heads 15 (hereinafter, sometimes also called a reference head) 15 with a predetermined spiral speed (hereinafter, sometimes also called a reference spiral speed).

[0063] The servo pattern control unit 620 performs touchdown measurements on each face 10S corresponding to each head 15 using each head 15. The touchdown measurement is performed by applying electricity to the heating element (heater) of the head 15 to cause thermal expansion, causing a portion of the head 15 to protrude towards the disk 10 and contact it. The applied electricity at the point of contact with the disk 10 (a control value of the gap between the head 15 and the disk 10, or the suspension amount of the head 15) is measured and detected. For example, in a self-servo writing (SSW) process (hereinafter sometimes referred to as the SSW process or SSW procedure), the servo pattern control unit 620 performs touchdown measurements on each face 10S corresponding to each head 15 based on a reference spiral servo pattern. In other words, for example, in the SSW process, the servo pattern control unit 620 locks the reference head 15 to the reference spiral servo pattern and performs touchdown measurements on each face 10S corresponding to each head 15 using each head 15.

[0064] The servo pattern control unit 620 performs R / W offset measurements on each head 15, measuring the R / W offset amount corresponding to each head 15. In the SSW process, for example, based on a reference spiral servo pattern, the servo pattern control unit 620 performs R / W offset measurements on each head 15, measuring the R / W offset amount corresponding to each head 15. In other words, in the SSW process, the servo pattern control unit 620, for example, locks the reference head 15 to the reference spiral servo pattern, performs R / W offset measurements on each head 15, and measures the R / W offset amount corresponding to each head 15.

[0065] The servo pattern control unit 620 writes the product servo pattern PSV to the disk 10. In the SSW process, the servo pattern control unit 620 writes the product servo pattern PSV based on the spiral servo pattern BSV. In the SSW process, the servo pattern control unit 620 corrects the R / W offset based on the spiral servo pattern BSV and the R / W offset, while writing the product servo pattern PSV from the inner direction in the radial direction, for example, the innermost IMC, towards the outer direction, for example, the outermost OMC. Alternatively, the servo pattern control unit 620 can also, in the SSW process, correct the R / W offset based on the spiral servo pattern BSV and the R / W offset, while writing the product servo pattern PSV from the outer direction in the radial direction, for example, the outermost OMC, towards the inner direction, for example, the innermost IMC.

[0066] In the SSW process, the servo pattern control unit 620 uses at least one of the multiple heads 15 as a reference head 15 to write the product servo pattern (hereinafter, sometimes also referred to as the reference product servo pattern) PSV to the reference surface 10S corresponding to the reference head 15, while correcting the R / W offset based on the reference spiral servo pattern BSV and the reference head 15.

[0067] The cylinder offset measuring unit 630 measures the cylinder offset. The cylinder offset measuring unit 630 measures the cylinder offset between data written through one of the plurality of heads 15 (hereinafter, sometimes referred to as a cylinder offset reference head) 15, such as tracks or sectors, and data written through a different head (hereinafter, sometimes referred to as a cylinder offset target head) 15, such as tracks or sectors. Furthermore, the cylinder offset measuring unit 630 can also measure the cylinder offset between one of the plurality of heads 15 (hereinafter, sometimes referred to as a cylinder offset reference head) 15 and a different head (hereinafter, sometimes referred to as a cylinder offset target head) 15. The cylinder offset measuring unit 630 records the measured cylinder offset in association with the head 15 corresponding to that cylinder offset, such as the cylinder offset target head 15, in a predetermined recording area, such as volatile memory 70, non-volatile memory 80, and buffer memory 90.

[0068] For example, the cylinder offset measuring unit 630 uses a predetermined head 15 among the multiple heads 15 as a reference via HDI (head Disk Interface) RampCal to measure the cylinder offset corresponding to each head 15. The cylinder offset measuring unit 630 records each cylinder offset measured with the predetermined head 15 among the multiple heads 15 as a reference in a predetermined recording area, such as a volatile memory 70, a non-volatile memory 80, and a buffer memory 90.

[0069] For example, the cylinder offset measuring unit 630 uses HDI (head Disk Interface) RampCal to measure the cylinder offset corresponding to each head 15, taking a predetermined head 15 among the multiple heads 15 as a reference, according to each partition. The cylinder offset measuring unit 630 records the cylinder offsets measured with the predetermined head 15 among the multiple heads 15 as a reference in a predetermined recording area, such as volatile memory 70, non-volatile memory 80, and buffer memory 90, according to each head and each partition.

[0070] The spiral copying control unit 640, based on a reference spiral servo pattern BSV, writes the spiral servo pattern (hereinafter, sometimes referred to as copying the spiral servo pattern) BSV to each surface (hereinafter, sometimes referred to as the spiral copying surface) 10S, which is different from the reference head 15, using each spiral copying head 15. In other words, the spiral copying control unit 640, based on the reference spiral servo pattern BSV, copies the reference spiral servo pattern BSV to each spiral copying surface 10S using each spiral copying head 15. The spiral copying control unit 640, based on the reference spiral servo pattern BSV accessed by the reference head 15, writes the copied spiral servo pattern BSV to the spiral copying surface 10S using the spiral copying head 15. In other words, the spiral copying control unit 640, based on the reference head 15, writes the copied spiral servo pattern BSV to the spiral copying surface 10S using the spiral copying head 15. Hereinafter, "copying the reference spiral servo pattern to the spiral copying surface 10S" is sometimes referred to as "performing spiral copying".

[0071] The spiral copy control unit 640 performs spiral copying on each spiral copy surface 10S through each spiral copy head 15 based on the offset of each cylindrical surface corresponding to each spiral copy head 15.

[0072] For example, the spiral copying control unit 640 adjusts the spiral speed (hereinafter sometimes referred to as the copying spiral speed) corresponding to each spiral copying head 15 according to the offset of each cylindrical surface corresponding to each spiral copying head 15, and performs spiral copying on each spiral copying surface 10S by each spiral copying head 15 with the adjusted spiral speed (hereinafter sometimes referred to as the adjusted copying spiral speed). For example, the spiral copying control unit 640 adjusts the copying spiral speed corresponding to each spiral copying head 15 to an adjusted copying spiral speed so that the offset of each cylindrical surface corresponding to each spiral copying head 15 is reduced, and performs spiral copying on each spiral copying surface 10S by each spiral copying head 15 with the adjusted copying spiral speed.

[0073] For example, the spiral copy control unit 640 adjusts the copy spiral speed of each partition corresponding to each spiral copy head 15 according to the cylinder offset of each partition. The spiral copy head 15 with the adjusted spiral speed of each partition (hereinafter sometimes referred to as the adjusted copy spiral speed) performs spiral copying on each spiral copy surface 10S. For example, the spiral copy control unit 640 adjusts the copy spiral speed of each partition corresponding to each spiral copy head 15 to an adjusted copy spiral speed, thereby reducing the cylinder offset of each partition corresponding to each spiral copy head 15. The spiral copy head 15 with the adjusted copy spiral speed of each partition then performs spiral copying on each spiral copy surface 10S.

[0074] By adjusting the spiral speed of the spiral copy head 15 to an adjustable copy spiral speed, the slope of the copied spiral servo pattern BSV on the spiral copy surface 10S corresponding to the spiral copy head 15 can be changed. By writing a product servo pattern (hereinafter, sometimes referred to as a copied product servo pattern) PSV onto the spiral copy surface 10S based on the copied spiral servo pattern (hereinafter, sometimes referred to as an adjusted copy spiral servo pattern) written to the spiral copy surface 10S by the spiral copy head 15 with the adjusted copy spiral speed, the deviation (cylindrical offset) between the reference product servo pattern PSV written based on the reference spiral servo pattern BSV and the copied product servo pattern PSV can also be adjusted. For example, by adjusting the copy spiral speed to an adjustable copy spiral speed that is larger than the reference spiral speed, the slope of the copied spiral servo pattern BSV becomes wider relative to the slope of the reference spiral servo pattern BSV. For example, by adjusting the copy spiral speed to an adjustable copy spiral speed that is smaller than the reference spiral speed, the slope of the copied spiral servo pattern BSV becomes narrower relative to the slope of the reference spiral servo pattern BSV.

[0075] The positioning control unit 650 performs positioning control on the head 15. The positioning control unit 650 performs positioning control on the head 15 based on the spiral servo pattern BSV and the product servo pattern PSV.

[0076] Figure 6 This is a schematic diagram illustrating an example of the correspondence between the reference head 15 and the spiral copy head 15. Figure 6 Table TB shows the header number, datum plane, and spiral replication plane. Figure 6 Table TB shows headers 15-(2m-4) to 15-(2m+4) and headers 15-(2n-4) to 15-(2n+4). Table TB can also be stored in a predetermined recording area, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0077] exist Figure 6 In the example shown, the MPU60 sets headers 15-(2m) and 15-(2n) as reference headers in table TB, for example. The MPU60 sets headers 15-(2m-4), 15-(2m-3), 15-(2m-2), 15-(2m-1), 15-(2m+1), 15-(2m+2), 15-(2m+3), 15-(2m+4), 15-(2n-4), 15-(2n-3), 15-(2n-2), 15-(2n-1), 15-(2n+1), 15-(2n+2), 15-(2n+3), and 15-(2n+4) as spiral copy headers.

[0078] The MPU60 writes the reference spiral servo pattern to the reference surface 10S(2m) via the reference head 15-(2m). The MPU60 writes the reference spiral servo pattern to the reference surface 10S(2n) via the reference head 15-(2n).

[0079] The MPU60 performs spiral replication based on the reference head 15-(2n) through the spiral replication heads 15-(2m-4), 15-(2m-3), 15-(2m-2), 15-(2m-1), 15-(2m+1), 15-(2m+2), 15-(2m+3), and 15-(2m+4) to the spiral replication surfaces 10S(2m-4), 10S(2m-3), 10S(2m-2), 10S(2m-1), 10S(2m+1), 10S(2m+2), 10S(2m+3), and 10S(2m+4). Based on the reference head 15-(2n), the MPU60 performs spiral replication sequentially to each spiral replication surface 10S(2m-4), 10S(2m-3), 10S(2m-2), 15-(2m-1), 15-(2m+1), 15-(2m+2), 15-(2m+3) and 15-(2m+4) through each spiral replication head 15-(2m-4) to 15-(2m+4) according to the offset of each cylindrical surface corresponding to each spiral replication head 15-(2m-4) to 15-(2m+4).

[0080] Based on the reference head 15-(2m), the MPU60 performs spiral replication through the spiral replication heads 15-(2n-4), 15-(2n-3), 15-(2n-2), 15-(2n-1), 15-(2n+1), 15-(2n+2), 15-(2n+3) and 15-(2n+4) to the spiral replication surfaces 10S(2n-4), 10S(2n-3), 10S(2n-2), 10S(2n-1), 10S(2n+1), 10S(2n+2), 10S(2n+3) and 10S(2n+4). Based on the reference head 15-(2m), the MPU60 performs spiral replication sequentially to each spiral replication surface 10S(2n-4), 10S(2n-3), 10S(2n-2), 15-(2n-1), 15-(2n+1), 15-(2n+2), 15-(2n+3) and 15-(2n+4) according to the offset of each cylindrical surface corresponding to each spiral replication head 15-(2n-4) to 15-(2n+4).

[0081] If spiral copying is performed via the head 15 close to the reference head 15, crosstalk occurs during the writing of the spiral servo pattern, potentially generating noise within the spiral servo pattern. Therefore, as... Figure 6 As shown, the MPU60 sets multiple heads 15 that are at a predetermined distance from the reference head 15, for example, at a predetermined distance in the height direction Z, as spiral copy heads 15.

[0082] Figure 7 This is a schematic diagram illustrating an example of the reference spiral servo pattern SVP1. Figure 7 In the diagram, the horizontal axis represents time, and the vertical axis represents the radial direction. Figure 7 On the vertical axis, it moves outwards towards the tip of the arrow and inwards towards the opposite direction. Figure 7 On the horizontal axis, time passes as it moves towards the front of the arrow.

[0083] exist Figure 7 In the example shown, the MPU60 writes the reference spiral servo pattern SVP1 to the reference plane 10S at the reference spiral speed SVL1 through the write head 15W of the reference head 15.

[0084] Figure 8 This is a schematic diagram illustrating an example of replicating the spiral servo pattern SVP2. Figure 8 In the diagram, the horizontal axis represents time, and the vertical axis represents the radial direction. Figure 8On the vertical axis, it moves outwards towards the tip of the arrow and inwards in the opposite direction. Figure 8 On the horizontal axis, time passes as you move towards the front of the arrow. Adjust the copying spiral speed SVL2 to be greater than the base spiral speed SVL1.

[0085] exist Figure 8 In the example shown, the MPU60 adjusts from the reference spiral speed SVL1 to the adjusted copy spiral speed SVL2, and writes the copied spiral servo pattern SVP2 onto the spiral copy surface 10S via the write head 15W of the spiral copy head 15 at the adjusted copy spiral speed SVL2. The copied spiral servo pattern SVP2 advances outwards compared to the reference spiral servo pattern SVP1 within a predetermined time.

[0086] Figure 9 This is a schematic diagram illustrating an example of how Gray code numbers change relative to a radius. Figure 9 In the diagram, the horizontal axis represents the radius position, and the vertical axis represents the Gray Code number. Figure 9 In the vertical axis, the Gray code number increases as it moves towards the front of the arrow and decreases as it moves towards the opposite side. Figure 9 In the horizontal axis, for the radius position, it moves outward as it moves towards the front of the arrow, and inward as it moves in the opposite direction to the front of the arrow. Figure 9 The diagram shows the Gray code number change relative to the radius position corresponding to the reference spiral servo pattern BSV (hereinafter, sometimes referred to as the change of Gray code number corresponding to the reference spiral servo pattern BSV) ESP, the Gray code number change corresponding to the copied spiral servo pattern (hereinafter, sometimes referred to as the comparison copied spiral servo pattern) written by the spiral copy head 15 at a copy spiral speed equivalent to the reference spiral speed (hereinafter, sometimes referred to as the change of Gray code number corresponding to the comparison copied spiral servo pattern) CSP, and the Gray code number change corresponding to the adjusted copied spiral servo pattern written by the spiral copy head 15 at an adjusted copy spiral speed (hereinafter, sometimes referred to as the change of Gray code number corresponding to the adjusted copied spiral servo pattern) BSP.

[0087] like Figure 9 As shown, the difference between the Gray code number change ESP corresponding to the reference spiral servo pattern BSV and the Gray code number change CSP corresponding to the comparison copy spiral servo pattern increases as the pattern moves outward. Therefore, the comparison copy spiral servo pattern may deviate relative to the reference spiral servo pattern BSV. Consequently, in a top-down view, the cylindrical offset between the reference spiral servo pattern BSV and the comparison copy spiral servo pattern may increase.

[0088] like Figure 9 As shown, the difference between the Gray code number change ESP corresponding to the reference spiral servo pattern BSV and the Gray code number BSP corresponding to the adjusted replica spiral servo pattern BSV is almost constant at the radius position. The Gray code number change ESP corresponding to the reference spiral servo pattern BSV and the Gray code number change BSP corresponding to the adjusted replica spiral servo pattern BSV are almost identical. Therefore, the reference spiral servo pattern BSV and the adjusted replica spiral servo pattern SV are almost identical. In a top-down view, the reference spiral servo pattern BSV and the adjusted replica spiral servo pattern BSV are almost identical.

[0089] Figure 10 This is a schematic diagram illustrating an example of the change in cylindrical offset relative to the radius position compared to the reference head 15, as described in this embodiment. Figure 10 In the diagram, the horizontal axis represents the radial position (radial direction), and the vertical axis represents the cylindrical offset. Figure 10 In the vertical axis, the cylindrical offset increases with the direction of the positive arrowhead and decreases with the direction of the negative arrowhead. Figure 10 In the horizontal axis, for the radius position (radial direction), it moves outward with the front end of the arrow pointing outward, and inward with the front end of the arrow pointing inward. Figure 10 The diagram shows the change in cylindrical offset relative to the radial position (radial direction) corresponding to reference head 15-(2m) and head 15-(2n). Hereinafter, the "change in cylindrical offset relative to the radial position (radial direction)" will sometimes be simply referred to as the "change in cylindrical offset". Figure 10 The diagram illustrates the changes in cylindrical offset COL1 for a spiral copy head 15 with an adjusted copy spiral speed increased by 0.06% relative to the reference spiral speed; COL2 for a spiral copy head 15 with an adjusted copy spiral speed increased by 0.03% relative to the reference spiral speed; COL3 for a spiral copy head 15 with an adjusted copy spiral speed decreased by 0.03% relative to the reference spiral speed; COL4 for a spiral copy head 15 with an adjusted copy spiral speed decreased by 0.06% relative to the reference spiral speed; and COL5 for a spiral copy head 15 with an adjusted copy spiral speed decreased by 0.09% relative to the reference spiral speed. Furthermore, errors in spiral speed that may naturally occur due to unintended construction and / or system factors are also considered. Figure 10 The magnitude shown is on the order of 1 / 100, therefore, it is possible to distinguish the errors that may arise naturally in the spiral velocity. Figure 10The change in the adjusted spiral speed is shown.

[0090] exist Figure 10 In the diagram, the changes in cylindrical offset (COL3) of spiral copy heads 15-(2m-4) and 15-(2m-3) correspond to the changes in cylindrical offset (COL2) of spiral copy heads 15-(2m-2) and 15-(2m-1) corresponding to the changes in cylindrical offset (COL2) of spiral copy heads 15 with an adjusted copy spiral speed increased by 0.03% relative to the reference spiral speed. The changes in cylindrical offset (COL4) of spiral copy heads 15-(2m+1) and 15-(2m+2) correspond to the changes in cylindrical offset (COL4) of spiral copy heads 15 with an adjusted copy spiral speed decreased by 0.03% relative to the reference spiral speed. The changes in cylindrical offset (COL1) of spiral copy heads 15-(2m+3) and 15-(2m+4) correspond to the changes in cylindrical offset (COL1) of spiral copy heads 15 with an adjusted copy spiral speed increased by 0.06% relative to the reference spiral speed. The changes in cylindrical offset for spiral copy heads 15-(2n-4) and 15-(2n-3) correspond to COL5, which is the change in cylindrical offset for spiral copy head 15 with an adjusted copy spiral speed reduced by 0.06% relative to the reference spiral speed. No data is available for spiral copy heads 15-(2n-2) and 15-(2n-1). The changes in cylindrical offset for spiral copy head 15-(2n+1) correspond to COL6, which is the change in cylindrical offset for spiral copy head 15 with an adjusted copy spiral speed reduced by 0.09% relative to the reference spiral speed. The changes in cylindrical offset for spiral copy head 15-(2n+2) correspond to COL4, which is the change in cylindrical offset for spiral copy head 15 with an adjusted copy spiral speed reduced by 0.03% relative to the reference spiral speed. No data is available for spiral copy heads 15-(2n+3) and 15-(2n+4).

[0091] exist Figure 10In the example shown, the changes in cylinder offset COL4 corresponding to the adjusted copying screw speed of the screw copying head 15, which is reduced by 0.03% relative to the reference screw speed, and COL5 corresponding to the adjusted copying screw speed of the screw copying head 15, which is reduced by 0.06% relative to the reference screw speed, are approximately equivalent to the changes in cylinder offset relative to the radial position (radial direction) COLR corresponding to the reference head 15-(2m) and head 15-(2n). The copied screw servo pattern written by the adjusted copying screw speed of the screw copying head 15, which is reduced by 0.03% relative to the reference screw speed, is almost identical to the reference screw servo pattern. Furthermore, the copied screw servo pattern written by the adjusted copying screw speed of the screw copying head 15, which is reduced by 0.06% relative to the reference screw speed, is almost identical to the reference screw servo pattern. The terms "identical," "same," "consistent," and "equivalent" not only include the meaning of being completely identical, but also include the meaning of having differences to the extent that they are considered substantially identical. Figure 10 In the example shown, the copied spiral servo pattern written by the spiral copy head 15, whose copy spiral speed is adjusted by 0.03% to 0.06% relative to the reference spiral speed, is almost identical to the reference spiral servo pattern. Figure 10 In the example shown, the copy spiral servo pattern written by the spiral copy head 15, which adjusts the copy spiral speed by 0.04% to 0.05% relative to the reference spiral speed, is likely to be the closest to the reference spiral servo pattern.

[0092] Figure 11 This is a schematic diagram illustrating an example of the change in cylindrical offset relative to the radius position compared to the predetermined head 15, as described in this embodiment. Figure 11 In the diagram, the horizontal axis represents the radial position (radial direction), and the vertical axis represents the cylindrical offset. Figure 11 On the vertical axis, the cylindrical offset increases with the direction of the positive arrowhead and decreases with the direction of the negative arrowhead. Figure 11 On the horizontal axis, the radius position (radial direction) moves outward with the front end of the arrow pointing outward, and inward with the front end of the arrow pointing inward. Figure 11 The diagram shows the variation group COVL of the cylindrical offset corresponding to each of the spiral copying heads 15-(2m-4) to 15-(2n+4) with an adjusted copying spiral speed relative to the reference spiral speed.

[0093] exist Figure 11In the example shown, the change group of cylindrical offsets (COVL) corresponding to the various adjusted copying spiral speeds of the spiral copying head 15-(2m-4) to 15-(2n+4) relative to the reference spiral speed is almost identical. Therefore, the multiple spiral servo patterns associated with the change group of cylindrical offsets (COVL) corresponding to the various adjusted copying spiral speeds of the spiral copying head 15-(2m-4) to 15-(2n+4) relative to the reference spiral speed are almost identical.

[0094] Figure 12 This is a schematic diagram illustrating an example of the SSW processing involved in this embodiment.

[0095] The MPU60 locks the reference head 15-(2m) onto the reference spiral servo pattern (B1201) written by the reference head 15-(2m), and performs landing (TD) measurement of the entire surface (B1202) through multiple heads 15-(2m-4) to 15-(2n+4). The MPU60 performs R / W offset measurement on the entire surface of the disk 10 through multiple heads 15-(2m-4) to 15-(2n+4) (B1203), and writes the product servo pattern (B1204) on the reference surface 10S corresponding to the reference head 15-(2m) based on the reference spiral servo pattern BSV written by the reference head 15-(2m).

[0096] The MPU60 locks the reference head 15-(2n) onto the reference spiral servo pattern (B1205) written through the reference head 15-(2n), and performs landing (TD) measurement of the entire surface (B1206) through multiple heads 15-(2m-4) to 15-(2n+4). Based on the reference spiral servo pattern BSV written through the reference head 15-(2n), the MPU60 writes the product servo pattern (B1207) onto the reference surface 10S corresponding to the reference head 15-(2n) through the reference head 15-(2n).

[0097] MPU60 uses a predetermined head 15 from a plurality of heads 15-(2m-4) to 15-(2n+4) as a reference to measure the cylinder offset corresponding to each head 15-(2m-4) to 15-(2n+4) (B1208). MPU60 stores the measured cylinder offset in a predetermined recording area, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90 (B1209).

[0098] Based on the reference spiral servo pattern written by the reference head 15-(2n), the MPU60 writes or copies multiple replica spiral servo patterns (B1210, B1211, and B1212) to multiple replica surfaces 10S(2m-4)~10S(2m-1), 10S(2m+1)~15-(2m+4) according to the multiple cylindrical offsets corresponding to the multiple spiral replica heads 15-(2m-4)~15-(2m-1), 15-(2m+1)~15-(2m+4) with adjusted replica spiral speeds.

[0099] Based on the reference spiral servo pattern written by the reference head 15-(2m), the MPU60 writes or copies multiple copy spiral servo patterns (B1213, B1214 and B1215) to multiple spiral copy surfaces 10S(2n-4)~10S(2n-1), 10S(2n+1)~15-(2n+4) according to the multiple cylindrical offsets corresponding to the multiple spiral copy heads 15-(2n-4)~15-(2n-1), 15-(2n+1)~15-(2n+4) with adjusted copy spiral speeds.

[0100] The MPU60 tracks the servo patterns of each replicated spiral using spiral replication heads 15-(2m-4)~15-(2m-1), 15-(2m+1)~15-(2m+4), 15-(2n-4)~15-(2n-1), and 15-(2n+1)~15-(2n+4). +4), 15-(2n-4)~15-(2n-1), 15-(2n+1)~15-(2n+4) write each spiral copy surface 10S(2m-4)~10S(2m-1), 10S(2m+1)~10S(2m+4), 10S(2n-4)~10S(2n-1), 10S(2n+1)~10S(2n+4) into the servo pattern (B1216) of each product, and end the processing.

[0101] According to this embodiment, the disk drive 1 locks the reference head 15 to the reference spiral servo pattern written through the reference head 15, and performs a landing measurement of the entire surface through multiple heads 15. The disk drive 1 performs R / W offset measurement on the entire surface of the disk through multiple heads 15, and writes a product servo pattern on the reference surface 10S corresponding to the reference head 15 based on the reference spiral servo pattern BSV written through the reference head 15. The disk drive 1 uses a predetermined head 15 among the multiple heads 15 as a reference and measures the cylinder offset corresponding to each head 15. The disk drive 1 stores the measured cylinder offset in a predetermined recording area, such as the system area 10b of the disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. Based on the reference spiral servo pattern written through the reference head 15 and based on the multiple cylinder offsets corresponding to the multiple spiral copy heads 15 respectively, the disk drive 1 writes or copies multiple copy spiral servo patterns on multiple spiral copy surfaces 10S respectively through multiple spiral copy heads 15 with adjusted copy spiral speeds. The disk device 1 writes each product servo pattern to each spiral copy surface for 10 seconds using each spiral copy head 15, based on each copy spiral servo pattern. The disk device 1 adjusts the spiral speed of each spiral copy head 15 to minimize the offset of each cylinder corresponding to each spiral copy head 15. Therefore, the disk device 1 can improve performance. Therefore, the disk device 1 can improve reliability.

[0102] Next, a modified version of the embodiment involving a disk device will be described. In the modified version, the parts that are the same as those in the aforementioned embodiment will be labeled with the same reference numerals and their detailed descriptions will be omitted.

[0103] (Variation Example 1)

[0104] The disk device 1 involved in Modification 1 has multiple cylinder offsets corresponding to multiple heads 15 in multiple disk devices, which is different from the disk device 1 in the aforementioned embodiments.

[0105] MPU60 records the average value (hereinafter sometimes referred to as cylinder offset average value) of multiple cylinder offsets corresponding to multiple heads 15 in multiple disk devices in a predetermined recording area, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. Alternatively, MPU60 can calculate the average value of multiple cylinder offsets corresponding to multiple heads 15 based on the multiple cylinder offsets in multiple disk devices, and record the calculated average value of multiple cylinder offsets in a predetermined recording area, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0106] MPU60 reads or references the average values ​​of multiple cylindrical offsets corresponding to the multiple spiral copy heads 15, which are recorded in a predetermined recording area. Based on the average values ​​of the cylindrical offsets corresponding to each spiral copy head 15, MPU60 writes or copies each spiral copy servo pattern to each spiral copy surface 10 seconds through each spiral copy head 15 that adjusts the speed of the copy spiral.

[0107] For example, the MPU60 writes or copies each copy spiral servo pattern to each spiral copy surface 10S by adjusting each spiral copy head 15 with an adjusted copy spiral speed so that the average offset of each cylindrical surface corresponding to each spiral copy head 15 is reduced.

[0108] When mechanical deviations are small across multiple disk devices, the deviation in cylinder offset for each disk device is presumed to be small as well. Therefore, based on the average cylinder offset corresponding to each spiral copy head 15, the deviation between each copy spiral servo pattern written by each spiral copy head 15, which adjusts the copy spiral speed, and the reference spiral servo pattern may also be small.

[0109] Figure 13 This is a schematic diagram illustrating an example of the SSW processing involved in Variation Example 1.

[0110] The MPU60 locks the reference head 15-(2m) onto the reference spiral servo pattern (B1201) written by the reference head 15-(2m), and performs landing (TD) measurement of the entire surface (B1202) through multiple heads 15-(2m-4) to 15-(2n+4). The MPU60 performs R / W offset measurement on the entire surface of the disk 10 through multiple heads 15-(2m-4) to 15-(2n+4) (B1203), and writes the product servo pattern (B1204) on the reference surface 10S corresponding to the reference head 15-(2m) based on the reference spiral servo pattern BSV written by the reference head 15-(2m).

[0111] The MPU60 locks the reference head 15-(2n) onto the reference spiral servo pattern (B1205) written through the reference head 15-(2n), and performs landing (TD) measurement of the entire surface (B1206) through multiple heads 15-(2m-4) to 15-(2n+4). Based on the reference spiral servo pattern BSV written through the reference head 15-(2n), the MPU60 writes the product servo pattern (B1207) to the reference surface 10S corresponding to the reference head 15-(2n) through the reference head 15-(2n).

[0112] MPU60 reads the average cylinder offset (B1301) corresponding to each spiral copy head 15 from a predetermined recording area, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0113] Based on the reference spiral servo pattern written by the reference head 15-(2n), the MPU60 writes or copies multiple replica spiral servo patterns (B1302, B1303, and B1304) to multiple replica surfaces 10S(2m-4)~10S(2m-1), 10S(2m+1)~15-(2m+4) respectively, based on the average value of multiple cylindrical surface offsets corresponding to multiple spiral replica heads 15-(2m-4)~15-(2m-1), 15-(2m+1)~15-(2m+4) with adjusted replica spiral speeds.

[0114] Based on the reference spiral servo pattern written by the reference head 15-(2m), the MPU60 writes or copies multiple copy spiral servo patterns (B1305, B1306, and B1307) to multiple spiral copy surfaces 10S(2n-4)~10S(2n-1), 10S(2n+1)~15-(2n+4) respectively, using multiple spiral copy heads 15-(2n-4)~15-(2n-1), 15-(2n+1)~15-(2n+4) that adjust the copy spiral speed, according to the reference spiral servo pattern written by the reference head 15-(2m).

[0115] The MPU60 tracks the servo patterns of each replicated spiral using spiral replication heads 15-(2m-4)~15-(2m-1), 15-(2m+1)~15-(2m+4), 15-(2n-4)~15-(2n-1), and 15-(2n+1)~15-(2n+4). +4), 15-(2n-4)~15-(2n-1), 15-(2n+1)~15-(2n+4) write each spiral copy surface 10S(2m-4)~10S(2m-1), 10S(2m+1)~10S(2m+4), 10S(2n-4)~10S(2n-1), 10S(2n+1)~10S(2n+4) into the servo pattern (B1216) of each product, and end the processing.

[0116] According to Variation 1, the disk drive 1 locks the reference head 15 to the reference spiral servo pattern written by the reference head 15, and performs a landing measurement of the entire surface by multiple heads 15. The disk drive 1 performs R / W offset measurement on the entire surface of the disk by multiple heads 15, and writes a product servo pattern on the reference surface 10S corresponding to the reference head 15 by the reference head 15 based on the reference spiral servo pattern BSV written by the reference head 15. The disk drive 1 reads the average cylinder offset corresponding to each spiral copy head 15 from a predetermined recording area, such as the system area 10b of the disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. The disk drive 1 writes or copies multiple copy spiral servo patterns on multiple spiral copy surfaces 10S by multiple spiral copy heads 15 that adjust the copy spiral speed, based on the reference spiral servo pattern written by the reference head 15 and the average cylinder offset corresponding to each of the multiple spiral copy heads 15. The disk device 1 writes each product servo pattern to each spiral copy surface for 10 seconds using each spiral copy head 15, based on each copy spiral servo pattern. The disk device 1 adjusts the spiral speed of each spiral copy head 15 to minimize the average offset of each cylinder corresponding to each spiral copy head 15. Therefore, the disk device 1 can improve performance. Therefore, the disk device 1 can improve reliability.

[0117] Several embodiments have been described, 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 various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and / or variations thereof are included in the scope and spirit of the invention, and are included in the scope of the invention as described in the claims and its equivalents.

Claims

1. A disk drive, comprising: A disk having a first surface and a second surface different from the first surface; The first head reads and writes the data on the first surface; The second head reads and writes data on the second surface; and A controller adjusts the spiral speed of at least one of the first and second heads for writing the spiral servo pattern based on a cylindrical offset amount corresponding to the deviation between the first and second heads. The controller uses the first head, which uses the reference spiral speed as a reference when writing the spiral servo pattern, to write the reference spiral servo pattern on the first surface, locks the first head (15) to the reference spiral servo pattern, and uses the second head, which uses the adjusted spiral speed obtained by adjusting the reference spiral speed, to write the spiral servo pattern on the second surface.

2. The disk drive according to claim 1, The controller measures the cylindrical offset and records the measured cylindrical offset in the recording area.

3. The disk drive according to claim 1 or 2, The controller measures the cylindrical offset according to each partition obtained by dividing the disk in the radial direction, and adjusts the spiral speed of at least one of the first head and the second head according to the cylindrical offset for each partition.

4. The disk drive according to claim 1, The adjusting screw speed is reduced by 0.03% to 0.06% compared to the reference screw speed.

5. The disk drive according to claim 1, The controller calculates the cylindrical offset as the average of multiple deviations between the first head and the second head.

6. A disk drive, comprising: Multiple disks, each with multiple sides; Multiple heads, each facing one of the multiple faces, including a first head facing a first face among the multiple faces; and The controller writes multiple spiral servo patterns onto the multiple surfaces using multiple heads operating at different spiral speeds at a constant velocity. The controller uses the first head, which serves as the reference spiral speed when writing the spiral servo pattern, to write the reference spiral servo pattern on the first surface, locks the first head (15) to the reference spiral servo pattern, and uses other heads among the plurality of heads whose spiral speeds are adjusted by adjusting the reference spiral speed to write spiral servo patterns on each surface opposite to each of the other heads.

7. An SSW method applied to a disk drive, the disk drive comprising: a disk having a first side and a second side different from the first side; a first head for reading and writing data on the first side; and a second head for reading and writing data on the second side. Based on a cylindrical offset amount corresponding to the deviation between the first head and the second head, adjust the spiral speed of at least one of the first head and the second head for writing the spiral servo pattern. The first head, using a reference spiral speed that serves as a reference when writing the spiral servo pattern, writes a reference spiral servo pattern on the first surface. The first head (15) is locked to the reference spiral servo pattern. The second head, using an adjusted spiral speed obtained by adjusting the reference spiral speed, writes a spiral servo pattern on the second surface.

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