Magnetic disk device

Abstract

Provided is a magnetic disk device capable of improving performance and data reliability. A magnetic disk device according to an embodiment includes: a disk having a first track; a head which has a heater and which writes data to and reads data from the disk; and a controller that divides the first track into a plurality of divided regions, and sets a plurality of refresh thresholds for executing rewrite processing for each of the plurality of divided regions in the first track. When it is determined that a first number of writes for data to an adjacent division region adjacent to a first division region in the radial direction of the disk among the plurality of division regions is greater than a first refresh threshold among the plurality of refresh thresholds corresponding to the first division region, processing for rewriting data is performed in the first track.

Description

[0001] This application is a divisional application of application No. 202210115844.5, filed on February 7, 2022, entitled "DISK DEVICE AND METHOD FOR SETTING REFRESH THRESHOLD". TECHNICAL FIELD

[0002] Embodiments of the present application relate to a disk device. BACKGROUND

[0003] With the high recording density of a disk (hereinafter, referred to as a disk) of a disk device, variations in recording and reproducing characteristics within one revolution of the disk due to unevenness of a magnetic film or the like of the disk or mechanical characteristics or the like are significantly visualized as variations in bit error rate (BER) or the like as an evaluation index. It is desired that the BER becomes constant at a predetermined track of the disk.

[0004] In addition, in the disk device, side erase in which data is erased can occur due to the influence of magnetic flux leakage from a head or the like (Adjacent Track Interference: ATI) in a case where data is written. In order to prevent side erase, the disk device has a process of rewriting data of a predetermined track (refresh process or rewrite process) in a case where the number of times of writing data to a track adjacent to the predetermined track exceeds a predetermined number of times. SUMMARY

[0005] An object of embodiments of the present application is to provide a disk device capable of improving performance and reliability of data.

[0006] The disk device according to the present embodiment includes a disk having a first track, a head having a heater that writes data to the disk and reads data from the disk, and a controller that divides the first track into a plurality of division areas, sets a plurality of refresh thresholds that perform a rewriting process in the first track for the plurality of division areas, respectively, and performs a process of rewriting data in the first track in a case where a first number of times of writing data to a first division area and a division area adjacent to the first division area in a radial direction of the disk is determined to be greater than a first refresh threshold among the plurality of refresh thresholds corresponding to the first division area. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a block diagram showing the configuration of a disk device of an embodiment.

[0008] Figure 2 is a schematic view showing an example of a disk of an embodiment.

[0009] Figure 3 is an enlarged cross-sectional view showing an example of a disk and a head.

[0010] Figure 4 is a schematic diagram showing an example of write processing.

[0011] Figure 5 is a schematic diagram showing an example of variations in the measured evaluation index, the approximate evaluation index, and the corrected evaluation index for the circumferential position of the intended track.

[0012] Figure 6 is a schematic diagram showing an example of variations in the corrected evaluation index for the circumferential position and variations in the corrected write processing parameter of the embodiment.

[0013] Figure 7 is a schematic diagram showing an example of variations in the BER for the circumferential position of the intended track in the case where fringe write is performed.

[0014] Figure 8 is a schematic diagram showing an example of variations in the TBG value for the circumferential position and variations in the threshold correction value for the circumferential position of the intended track of the embodiment.

[0015] Figure 9 is a schematic diagram showing an example of variations in the division region threshold for the division region of the intended track of the embodiment.

[0016] Figure 10 is a schematic diagram showing an example of the division region of the intended track.

[0017] Figure 11 is a schematic diagram showing an example of the table TB of the write number and the division region threshold of the embodiment.

[0018] Figure 12 is a flowchart showing an example of the setting method of the refresh threshold of the embodiment.

[0019] Figure 13 is a schematic diagram showing an example of the refresh processing method of the embodiment.

[0020]

Label Explanation

[0021] 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... drive IC, 30... head amplifier IC, 40... read / write (R / W) channel, 50... hard disk controller (HDC), 60... microprocessor (MPU), 70... volatile memory, 80... nonvolatile memory, 90... buffer memory, 100... host system (host), 130... system controller. DETAILED DESCRIPTION

[0022] 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 application.

[0023] (Embodiment)

[0024] Figure 1 is a block diagram showing the configuration of a magnetic disk device 1 of an embodiment.

[0025] The magnetic disk device 1 is provided with a head disk assembly (HDA) to be described later, 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 as a single-chip integrated circuit. In addition, the magnetic disk device 1 is connected to a host system (hereinafter, simply referred to as a host) 100.

[0026] The HDA has a magnetic disk (hereinafter, referred to as a disk) 10, a spindle motor (hereinafter, referred to as an SPM) 12, an arm 13 on which a head 15 is mounted, and a voice coil motor (hereinafter, referred to as a VCM) 14. The disk 10 is mounted to the SPM 12, and rotates by driving of the SPM 12. The arm 13 and the VCM 14 constitute an actuator. The actuator moves and controls the head 15 mounted on the arm 13 to a predetermined position of the disk 10 by driving of the VCM 14. The disk 10 and the head 15 can be provided in a number of two or more.

[0027] The disk 10 is provided with a user data area 10a which can be written by a user and a system area 10b in which information required for system management is written. Hereinafter, a direction from an inner periphery of the disk 10 toward an outer periphery or a direction from an outer periphery of the disk 10 toward an inner periphery is referred to as a radial direction. In the radial direction, a direction from the inner periphery toward the outer periphery is referred to as an outer direction (or an outer side), and a direction from the inner periphery toward the outer periphery is referred to as an inner direction (or an inner side). A circumferential direction corresponds to a direction along a circumference of the disk 10. The radial direction and the circumferential direction are orthogonal to each other. In addition, there are cases in which a predetermined position of the disk 10 in the radial direction is referred to as a radial position, and a predetermined position of the disk 10 in the circumferential direction is referred to as a circumferential position. There are also cases in which the radial position and the circumferential position are collectively referred to as a position. The user data area 10a of the disk 10 can be divided into a plurality of areas. For example, the user data area 10a can be divided in the radial direction by each area (hereinafter, there are cases in which it is also referred to as a zone) containing a predetermined number of tracks. The zone can be divided in the radial direction by each track.

[0028] Further, "track" is used in the meaning of one of a plurality of recording areas that divide the disk 10 in the radial direction, one recording area of a predetermined amount of one revolution at a predetermined radial position of the disk 10, a predetermined recording area at a predetermined radial position of the disk 10, a recording area that extends in the circumferential direction of the disk 10, a recording area that corresponds to a path of the head 15 positioned at a predetermined radial position of the disk 10, a path of the head 15 positioned at a predetermined radial position of the disk 10, data written to one of a plurality of recording areas that divide the disk 10 in the radial direction, data written to one recording area of a predetermined amount of one revolution at a predetermined radial position of the disk 10, data written to a predetermined recording area at a predetermined radial position of the disk 10, data written to a recording area that extends in the circumferential direction of the disk 10, data written to a recording area that corresponds to a path of the head 15 positioned at a predetermined radial position of the disk 10, data written along a path of the head 15 positioned at a predetermined radial position of the disk 10, data that extends in the circumferential direction in the disk 10, data written to a predetermined track of the disk 10, data of a predetermined amount of one revolution written to a predetermined track of the disk 10, a portion of data written to a predetermined track of the disk 10, and other various meanings. "Sector" is used in the meaning of one of a plurality of recording areas that divide a predetermined track of the disk 10 in the circumferential direction, one of a plurality of recording areas that divide a recording area that extends in the circumferential direction at a predetermined radial position of the disk 10, a predetermined recording area of a predetermined track of the disk 10, a predetermined circumferential position of a predetermined track of the disk 10, a predetermined circumferential position at a predetermined radial position of the disk 10 (predetermined position), data written to one of a plurality of recording areas that divide a predetermined track of the disk 10 in the circumferential direction, data written to one of a plurality of recording areas that divide a recording area that extends in the circumferential direction at a predetermined radial position of the disk 10, data written to a predetermined recording area of a predetermined track of the disk 10, data written to a predetermined circumferential position of a predetermined track of the disk 10, data written to a predetermined circumferential position at a predetermined radial position of the disk 10 (predetermined position), data written to a predetermined sector, and other various meanings. There are also cases where the "radial direction width of a track" is referred to as "track width". There are also cases where a "path that passes through a center position of a track width of a predetermined track" is referred to as "track center". There are also cases where data that is written to the user data area 10a and that can be utilized by a user is referred to as user data.

[0029] The head 15 has a slider 150 as a main body, and has a write head 15W and a read head 15R attached to the slider 150. The write head 15W writes data to the disc 10. The read head 15R reads data recorded on the disc 10. In addition, there are cases where the "write head 15W" is simply referred to as the "head 15", cases where the "read head 15R" is simply referred to as the "head 15", and cases where the "write head 15W and the read head 15R" are collectively referred to as the "head 15". There are also cases where the "central portion of the write head 15W" is simply referred to as the "head 15", cases where the "central portion of the read head 15R" is simply referred to as the "head 15", and cases where the "central portion of the head 15" is positioned at the center of the track of a predetermined track to be expressed as "positioning the head 15 at the predetermined track", "arranging the head 15 at the predetermined track", or "locating the head 15 at the predetermined track".

[0030] Figure 2 is a schematic view showing an example of the disc 10 according to the embodiment. As shown in Figure 2 , the direction in which the disc 10 is rotated is referred to as the rotation direction in the circumferential direction. In addition, in the example shown in Figure 2 , the rotation direction is shown in counterclockwise, but it can be reversed (clockwise). In Figure 2 , the disc 10 is divided into an inner circumferential region IR located in the inner direction, an outer circumferential region OR located in the outer direction, and a middle circumferential region MR located between the inner circumferential region IR and the outer circumferential region OR.

[0031] In the example shown in Figure 2 , the disc 10 includes a user data area 10a and a system area 10b. In Figure 2 , the user data area 10a and the system area 10b are adjacent in the radial direction. Here, the "adjacent" naturally includes contact arrangement of data, objects, regions, spaces, and the like, and includes arrangement with a predetermined interval therebetween. In Figure 2 , the system area 10b is adjacent to the user data area 10a in the outer direction. In addition, the system area 10b can be adjacent to the user data area 10a in the inner direction. Further, the system area 10b can be arranged between the user data area 10a in the radial direction.

[0032] In the example shown in Figure 2 , the user data area 10a is arranged from the inner circumferential region IR to the outer circumferential region OR. The system area 10b is arranged in the outer circumferential region OR. In addition, the system area 10b can be arranged in the inner circumferential region IR or the middle circumferential region MR. The system area 10b can be arranged dispersedly in the outer circumferential region OR, the middle circumferential region MR, or the inner circumferential region IR.

[0033] As Figure 3 shown, the head 15 is disposed at a predetermined position by rotation around a rotation axis and movement from an inner direction toward an outer direction by driving of the VCM 14, or movement from an outer direction toward an inner direction, with respect to the disk 10.

[0034] Figure 3 is an enlarged sectional view showing an example of the disk 10 and the head 15. Hereinafter, a direction from the head 15 toward the disk 10 will be referred to as a lower direction (or down), and a direction from the disk 10 toward the head 15 will be referred to as an upper direction (or up). In Figure 3 , the rotation direction B of the disk 10 coincides with the direction of the air flow C.

[0035] In Figure 3 the example shown, the disk 10 has a substrate 111, a soft magnetic layer 112, a magnetic recording layer 113, and a protective film layer 114 laminated in this order. The substrate 111 is formed of a non-magnetic body in a circular plate shape. The soft magnetic layer 112 is formed of a material exhibiting soft magnetic characteristics on the substrate 111. The magnetic recording layer 113 has magnetic anisotropy in a direction perpendicular to the surface of the disk 10 on the soft magnetic layer 112. The protective film layer 114 is formed on the magnetic recording layer 113.

[0036] In Figure 3 the example shown, the head 15 has a slider 150. The slider 150 is formed of, for example, a sintered body of alumina and titanium carbide (Altic). The slider 150 has a disk-opposing surface (air bearing surface (ABS)) 151 opposing the surface of the disk 10, and a trailing end 153 located on the outflow side of the air flow C. The slider 150 includes a write head 15W, a read head 15R, a heater 191, and a heater 192. A part of the read head 15R and the write head 15W is exposed to the disk-opposing surface 151. The heater 191 is disposed between the write head 15W and the read head 15R. The heater 192 is disposed on the side opposite to the write head 15W with respect to the read head 15R. In other words, the read head 15R is disposed between the heaters 191 and 192.

[0037] The read head 15R is composed of a magnetic film 161, a shield film 162, and a shield film 163. The magnetic film 161 is located between the shield film 162 and the shield film 163, and generates a magnetoresistance effect. The shield film 162 is located on the trailing end 153 side with respect to the magnetic film 161. The shield film 163 opposes the shield film 162. The lower ends of the magnetic film 161, the shield film 162, and the shield film 163 are exposed to the disk-opposing surface 151.

[0038] The write head 15W is provided on the trailing end 153 side of the slider 150 with respect to the read head 15R. The write head 15W has a main pole 171, a trailing shield (write shield) 172, and a recording coil 180 configured to be wound around a magnetic circuit including the main pole 171 and the write shield 172 in order to cause magnetic flux to flow to the main pole 171.

[0039] The main pole 171 is formed of a soft magnetic body having a high saturation magnetic flux density. The main pole 171 generates a recording magnetic field in a direction perpendicular to the surface of the disk 10 in order to magnetize the magnetic recording layer 113 of the disk 10. The main pole 171 is formed of a soft magnetic body having a high saturation magnetic flux density. The main pole 171 generates a recording magnetic field in a direction perpendicular to the surface of the disk 10 in order to magnetize the magnetic recording layer 113 of the disk 10. In the example shown, the main pole 171 extends almost perpendicularly with respect to the disk opposing surface 151. The lower surface of the front end portion 171a of the main pole 171 on the disk opposing surface 151 side is exposed to the disk opposing surface 151. The front end portion 171a of the main pole 171 is taperedly narrowed toward the disk opposing surface 151 and formed in a columnar shape having a narrow width with respect to other portions. The width of the front end portion 171a of the main pole 171 in the cross track direction almost corresponds to the track width of the magnetic track. The cross track direction is, for example, a direction along the radial direction. Figure 4

[0040] The write shield 172 is formed of a soft magnetic body having a high saturation magnetic flux density. The write shield 172 is provided in order to effectively close the magnetic circuit via the soft magnetic layer 112 directly below the main pole 171. The write shield 172 is located on the trailing end 153 side with respect to the main pole 171. The write shield 172 is joined to the main pole 171 via the insulator 173. The main pole 171 and the write shield 172 are electrically insulated and form a magnetic circuit. The write shield 172 is formed in a substantially L shape and has a front end portion 172a that opposes the front end portion 171a of the main pole 171 with the write gap therebetween. The lower surface of the front end portion 172a is exposed to the ABS 151 of the slider 150.

[0041] The recording coil 180 is provided so as to be wound around the magnetic circuit including the main pole 171 and the write shield 172 in order to cause the magnetic flux to flow to the main pole 171. The recording coil 180 is provided, for example, between the main pole 171 and the write shield 172. By supplying a current of a predetermined size to the recording coil 180 (there are cases where this is referred to as a recording current (Iw) or a write current (Iw)), a recording magnetic field is excited in the main pole 171 and the write shield 172. Thus, the main pole 171 and the write shield 172 are magnetized. By changing the magnetization direction of the recording bits of the magnetic recording layer 113 of the disk 10 using the magnetic flux flowing in the main pole 171 and the write shield 172 after magnetization, a magnetization pattern corresponding to the recording current is recorded in the disk 10.

[0042] The driver IC 20 controls the driving of the SPM 12 and the VCM 14 in accordance with the control of the system controller 130 (in detail, the MPU 60 described later).

[0043] ​The head amplifier IC (pre-amplifier) 30 has a read amplifier, a write driver such as a recording current control section 310, and a heater control section 320. The read amplifier amplifies a read signal read from the disc 10 and outputs the read signal to the system controller 130 (in detail, a read / write (R / W) channel 40 described later). The recording current control section 310 is electrically connected to the write head 15W and supplies a recording current corresponding to write data output from the R / W channel 40 to the write head 15W. In one example, the recording current control section 310 is electrically connected to the recording coil 180 and supplies a recording current corresponding to write data output from the R / W channel 40 to the recording coil 180. The recording current control section 310 supplies the recording current to the write head 15W in accordance with control of the system controller 130, for example, an MPU 60. For example, the recording current control section 310 supplies the recording current to the recording coil 180 in accordance with control of the MPU 60. The heater control section 320 is electrically connected to the heaters 191 and 192 and supplies a current for driving the heaters to the heaters 191 and 192 output from the R / W channel 40. The heater control section 320 supplies the current to the heaters 191 and 192 in accordance with control of the system controller 130, for example, the MPU 60. When the heater control section 320 supplies the current to the heaters 191 and 192, the heaters 191 and 192 generate heat and heat a portion of the slider 150 around the heaters 191 and 192. Thus, the slider 150, the write head 15W, and the read head 15R thermally expand and the ABS 151 protrudes toward the surface side of the disc 10. In this way, the amount of float (the distance of the ABS 151 from the surface of the disc 10) of the head 15 can be adjusted by the heaters 191 and 192. The amount of expansion of the slider 150, the write head 15W, and the read head 15R is adjusted in accordance with the value of the current (or voltage) supplied to the heaters 191 and 192. That is, the amount of float of the head 15 is adjusted in accordance with the value of the current (or voltage) supplied to the heaters 191 and 192.

[0044] The volatile memory 70 is a semiconductor memory in which data saved when power supply is cut off is lost. The volatile memory 70 stores data and the like required for processing in each part of the disc device 1. The volatile memory 70 is, for example, a DRAM (Dynamic Random Access Memory) or a SDRAM (Synchronous Dynamic Random Access Memory).

[0045] The non-volatile memory 80 is a semiconductor memory in which saved data is recorded even when power supply is cut off. The non-volatile memory 80 is, for example, a NOR type or a NAND type flash ROM (Flash Read Only Memory: FROM).

[0046] The buffer memory 90 is a semiconductor memory that temporarily records data and the like that are transmitted and received between the disk device 1 and the host 100. Further, the buffer memory 90 can be integrally configured with the volatile memory 70. The buffer memory 90 is, for example, a DRAM, a SRAM (Static Random Access Memory), a SDRAM, a FeRAM (Ferroelectric Random Access memory), or an MRAM (Magnetoresistive Random Access Memory), or the like.

[0047] The system controller (controller) 130 is realized, for example, using a large-scale integrated circuit (LSI) called a System-on-a-Chip (SoC) in which a plurality of elements are integrated in 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 system controller 130 is electrically connected to, for example, the drive IC 20, the head amplifier IC 30, the volatile memory 70, the non-volatile memory 80, the buffer memory 90, and the host 100.

[0048] The R / W channel 40 performs signal processing of read data transmitted from the disk 10 to the host 100 and write data transmitted from the host 100 according to an instruction from the MPU 60 described later. The R / W channel 40 has a circuit or a function that measures the signal quality of the read data. The R / W channel 40 is electrically connected to, for example, the head amplifier IC 30, the HDC 50, the MPU 60, and the like.

[0049] The HDC 50 controls transmission of data. For example, the HDC 50 controls transmission of data between the host 100 and the R / W channel 40 according to an instruction from the MPU 60 described later. The HDC 50 is electrically connected to, for example, the R / W channel 40, the MPU 60, the volatile memory 70, the non-volatile memory 80, the buffer memory 90, and the like.

[0050] The MPU 60 is a main controller that controls each part of the disk device 1. The MPU 60 performs servo control that controls positioning of the head 15 by the VCM 14 via the drive IC 20. The MPU 60 controls the SPM 12 via the drive IC 20 to rotate the disk 10. The MPU 60 controls a write operation of data to the disk 10, and selects a storage destination of data such as write data transmitted from the host 100. The MPU 60 controls a read operation of data from the disk 10, and controls processing of data such as read data transmitted from the disk 10 to the host 100. In addition, the MPU 60 manages a region in which data is recorded. The MPU 60 is connected to each part of the disk device 1. The MPU 60 is electrically connected to, for example, the drive IC 20, the R / W channel 40, the HDC 50, and the like.

[0051] The MPU 60 has a read / write control section 610, an access processing control section 620, a refresh control section 630, and the like. The MPU 60 executes processing of each section such as the read / write control section 610, the access processing control section 620, and the refresh control section 630 on firmware. Further, the MPU 60 can also have each section such as the read / write control section 610, the access processing control section 620, and the refresh control section 630 as a circuit. The read / write control section 610, the access processing control section 620, and the refresh control section 630, and the like can also be included in the R / W channel 40 or the HDC 50.

[0052] The read / write control section 610 controls a read process of reading data from the disc 10 and a write process of writing data to the disc 10 in accordance with a command or the like from the host 100. The read / write control section 610 controls the VCM 14 via the drive IC 20 to position the head 15 at a predetermined position of the disc 10, and executes the read process or the write process. Hereinafter, there are also cases where the term "access" is used in the sense of including recording or writing data (or a write process) to a predetermined area, reading out or reading data (or a read process) from a predetermined area, and moving the head 15 or the like to a predetermined area.

[0053] The read / write control section 610 performs a normal recording of writing data to a predetermined area of the disc 10 at a predetermined interval (gap) in the radial direction from a predetermined track or writing data at random in accordance with a command or the like from the host 100. Further, the read / write control section 610 can also perform a pad recording of writing a next track to a part of a track in the radial direction for each predetermined area (hereinafter, also referred to as a band or a band area) of the disc 10 in accordance with a command or the like from the host 100. Hereinafter, there are also cases where the "normal recording" and / or the "pad recording" are simply expressed as "writing". There are also cases where writing to an adjacent track of a predetermined track is referred to as "edge writing".

[0054] Figure 4 is a schematic view showing an example of the write process. Figure 4 In, a traveling direction in the circumferential direction is shown. There are also cases where a direction in which the head 15 sequentially writes and reads data with respect to the disc 10 in the circumferential direction, that is, a direction in which the head 15 travels with respect to the disc 10 in the circumferential direction is referred to as a traveling direction. For example, the traveling direction is a direction opposite to a direction of rotation of the disc 10. Further, the traveling direction can also be a direction identical to the direction of rotation of the disc 10. In the circumferential direction, there are also cases where the traveling direction is referred to as a rear direction or simply a rear. In the circumferential direction, there are also cases where a direction opposite to the rear direction is referred to as a front direction or simply a front. Figure 4 In, tracks CTRn-1, CTRn, and CTRn+1 are shown. In, a track CTRn is shown. Figure 4In the present embodiment, for example, the track widths of the tracks CTRn-1, CTRn, and CTRn+1 are the same. The terms "same", "identical", "uniform", and "equivalent" of course include the meaning of being completely the same, and also include the meaning of being different to the extent that can be considered to be substantially the same. In addition, the track widths of the tracks CTRn-1 to CTRn+1 can also be different. Figure 4 In the present embodiment, the track center CTCn-1 of the track CTRn-1, the track center CTCn of the track CTRn, and the track center CTCn+1 of the track CTRn+1 are shown. In the present embodiment, the track center CTCn-1 of the track CTRn-1, the track center CTCn of the track CTRn, and the track center CTCn+1 of the track CTRn+1 are shown. Figure 4 In the example shown, the tracks CTRn-1, CTRn, and CTRn+1 are written with the track pitch CTP. The track center CTCn-1 of the track CTRn-1 is separated from the track center CTCn of the track CTRn by the track pitch CTP. The track center CTCn of the track CTRn is separated from the track center CTCn+1 of the track CTRn+1 by the track pitch CTP. The track CTRn-1 and the track CTRn are separated by the gap GP. The track CTRn and the track CTRn+1 are separated by the gap GP. In addition, the tracks CTRn-1 to CTRn+1 can also be written with different track pitches. In the present embodiment, the tracks CTRn-1 to CTRn+1 are written with the same track pitch CTP. Figure 4 In the present embodiment, for convenience of explanation, each track is shown as a long rectangular shape extending in the circumferential direction with a predetermined track width, but in reality, is curved along the circumferential direction. In addition, each track can also be a wavy shape extending in the circumferential direction while varying in the radial direction.

[0055] In the present embodiment, the read / write control section 610 positions the head 15 at the track center CTCn-1 of the track CTRn-1 in a predetermined area of the disc 10, and performs writing (or normal recording) to a predetermined sector of the track CTRn-1 or the track CTRn-1. Figure 5 In the example shown, the read / write control section 610 positions the head 15 at the track center CTCn-1 of the track CTRn-1 in a predetermined area of the disc 10, and performs writing (or normal recording) to a predetermined sector of the track CTRn-1 or the track CTRn-1.

[0056] The read / write control section 610 positions the head 15 at the track center CTCn-1 of the track CTRn-1 in a predetermined area of the disc 10, and performs writing (or normal recording) to a predetermined sector of the track CTRn-1 or the track CTRn-1.

[0057] The read / write control section 610 positions the head 15 at the track center CTCn-1 of the track CTRn-1 in a predetermined area of the disc 10, and performs writing (or normal recording) to a predetermined sector of the track CTRn-1 or the track CTRn-1.

[0058] The read / write control unit 610 can sequentially write (or normally record) tracks CTRn-1, CTRn, and CTRn+1 in a predetermined area of ​​disk 10, or randomly write (or normally record) predetermined sectors of track CTRn-1, track CTRn, and track CTRn+1.

[0059] The access processing control unit 620 controls access processing, such as write processing and read processing. Based on evaluation metrics corresponding to the write and read processing characteristics of a predetermined recording area of ​​the disk 10, such as a partition, track, or sector, the access processing control unit 620 controls characteristic values ​​corresponding to write processing (hereinafter, also referred to as write processing parameters or simply parameters). Evaluation metrics include, for example, error rate (bit error rate: BER). Write processing parameters include, for example, recording density (Bits Per Inch: BPI), recording current, a heater setting value equivalent to the value of the current (or voltage) applied to the heater, data transfer speed, and the recording frequency (hereinafter, also referred to as recording frequency) when writing data corresponding to the recording density of the predetermined area. For ease of explanation, the following interpretations are also provided: "BER of data written to a predetermined recording area" is abbreviated as "BER of the predetermined recording area"; "recording density of data written to a predetermined recording area" is abbreviated as "recording density of the predetermined recording area"; "recording current when writing data to a predetermined recording area" is abbreviated as "recording current of the predetermined recording area"; "heater setting value when writing data to a predetermined recording area" is abbreviated as "heater setting value of the predetermined recording area"; "data transfer speed when writing data to a predetermined recording area" is abbreviated as "transfer speed of the predetermined recording area"; and "recording frequency when writing data to a predetermined recording area" is abbreviated as "recording frequency of the predetermined recording area". Evaluation metrics may also include the meaning of the frequency of the signal corresponding to the evaluation metric. BER may also include the meaning of the frequency of the signal corresponding to the BER. Write processing parameters may also include the meaning of the frequency of the signal corresponding to the write processing parameters. Recording density, recording current, heater setting value, transfer speed, or recording frequency may also include the meaning of the frequency of the signal corresponding to the recording density, recording current, heater setting value, transfer speed, or recording frequency.

[0060] The access processing control unit 620 controls the changes in the write processing parameters of the track within one week based on the changes in the evaluation indicators (hereinafter also referred to as changes in evaluation indicators) of the predetermined track within one week, such as the changes in the BER of the track within one week (hereinafter also referred to as changes in BER). These changes include the changes in the recording density of the track within one week (hereinafter also referred to as changes in recording density), the changes in the recording current of the track within one week (hereinafter also referred to as changes in recording current), the changes in the heater setting value of the track within one week (hereinafter also referred to as changes in heater setting value), the changes in the transfer speed of the track within one week (hereinafter also referred to as changes in transfer speed), or the changes in the recording frequency of the track within one week (hereinafter also referred to as changes in recording frequency).

[0061] The access processing control unit 620 controls write processing parameters for each predetermined region of a predetermined track, such as the record density, record current, heater setting, transfer speed, or record frequency, based on evaluation metrics for each region (hereinafter also referred to as a segmented region) of the predetermined track, including the BER of each segmented region. A segmented region corresponds to one of multiple regions divided into the predetermined track in the circumferential direction. A segmented region may, for example, be composed of multiple sectors within the predetermined track. Furthermore, the circumferential lengths of the segmented regions can be the same or different. In other words, multiple segmented regions of the predetermined track can have the same number of sectors or different numbers of sectors. Additionally, a segmented region may also correspond to one sector of the predetermined track.

[0062] The access processing control unit 620 controls each write processing parameter of each circumferential position of the predetermined track based on each evaluation index of each circumferential position of the predetermined track, such as each BER of each circumferential position of the predetermined track, such as each recording density, each recording current, each heater setting value, each transfer speed or each recording frequency of each circumferential position of the track.

[0063] The access processing control unit 620 controls the write processing parameters of each sector of the predetermined track based on the evaluation indicators of each sector of the predetermined track, such as the BER of each sector of the predetermined track. These parameters include the recording density, recording current, heater setting value, transfer speed, or recording frequency of each sector of the track.

[0064] The access processing control unit 620 sets the write processing parameters on a predetermined track to a certain write processing parameter (hereinafter also referred to as a reference write processing parameter) as a reference, and measures the change in the evaluation index on that track (hereinafter also referred to as the change in the measured evaluation index). Based on the measured change in the measured evaluation index of that track, the access processing control unit 620 calculates the change in the write processing parameter relative to the reference write processing parameter on that track, used to adjust the change in the measured evaluation index to be uniform or suppressed (hereinafter also referred to as the change in the write processing parameter correction amount or the change in the write processing parameter variation). The access processing control unit 620 adds (or subtracts) the change in the write processing parameter correction amount to the reference write processing parameter on that track. As a result, the access processing control unit 620 corrects (or adjusts) the reference write processing parameter of that track to the change in the write processing parameter of that track (hereinafter also referred to as the change in the corrected write processing parameter or the change in the corrected parameter). The access processing control unit 620 sets the change in the corrected write processing parameter for that track.

[0065] Furthermore, the access processing control unit 620, either idle or in real-time, sets the write processing parameters on a predetermined track as reference write processing parameters and measures the changes in the measured evaluation index on that track. Based on the measured changes in the measured evaluation index of that track, the access processing control unit 620 calculates the change in the write processing parameter correction amount for that track, either idle or in real-time. The access processing control unit 620 adds (or subtracts) the change in the write processing parameter correction amount to the reference write processing parameters on that track, either idle or in real-time. Thus, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of that track to the change in the corrected write processing parameters of that track, either idle or in real-time. The access processing control unit 620 sets the change in the corrected write processing parameters for that track, either idle or in real-time. Additionally, the access processing control unit 620 can also store the changes in each corrected write processing parameter on each track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0066] For example, the access processing control unit 620 sets the recording density, recording current, heater setting value, transfer speed, or recording frequency on a predetermined track to a certain recording density (hereinafter also referred to as a reference recording density), a certain recording current (hereinafter also referred to as a reference recording current), a certain heater setting value (hereinafter also referred to as a reference heater setting value), a certain transfer speed (hereinafter also referred to as a reference transfer speed), or a certain recording frequency (hereinafter also referred to as a reference recording frequency), and measures the change in BER on that track (hereinafter also referred to as the change in measured BER). Based on the measured BER variation of the track, the access processing control unit 620 calculates the variation of the recording density relative to the reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency on the track, for adjusting the variation of the measured BER of the track to be uniform or suppressed. These variations include the variation of the recording density (hereinafter also referred to as the variation of recording density correction amount or the variation of recording density variation), the variation of the recording current (hereinafter also referred to as the variation of recording current correction amount or the variation of recording current variation), the variation of the heater setting value (hereinafter also referred to as the variation of heater setting value correction amount or the variation of heater setting value variation), the variation of the transport speed (hereinafter also referred to as the variation of transport speed correction amount or the variation of transport speed variation), and the variation of the recording frequency (hereinafter also referred to as the variation of recording frequency correction amount or the variation of recording frequency variation). The access processing control unit 620 adds (or subtracts) changes in recording density correction, recording current correction, heater setting correction, transport speed correction, or recording frequency correction to the reference recording density, reference recording current, reference heater setting, reference transport speed correction, or recording frequency correction of the track. As a result, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of the track to changes in recording density (hereinafter, this may also be referred to as correcting changes in recording density), recording current (hereinafter, this may also be referred to as correcting changes in recording current), heater setting (hereinafter, this may also be referred to as correcting changes in heater setting), transport speed (hereinafter, this may also be referred to as correcting changes in transport speed), or recording frequency (hereinafter, this may also be referred to as correcting changes in recording frequency). The access processing control unit 620 sets corrections for changes in recording density, recording current, heater setting, transport speed, or recording frequency of the track.The access processing control unit 620 can also store changes in correction recording density, correction recording current, correction heater setting, correction transfer speed, or correction recording frequency on each track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0067] The access processing control unit 620 sets each write processing parameter at each circumferential position on a predetermined track as a reference write processing parameter, and measures each evaluation index (hereinafter, also referred to as a measured evaluation index) at each circumferential position of the track. Based on the measured evaluation indexes at each circumferential position of the track, the access processing control unit 620 calculates the change in each write processing parameter at each circumferential position relative to the reference write processing parameters at each circumferential position of the track, used to adjust the measured evaluation indexes at each circumferential position of the track to be uniform or suppressed (hereinafter, also referred to as a write processing parameter correction amount or write processing parameter change amount). The access processing control unit 620 adds (or subtracts) the write processing parameter correction amount at each circumferential position to the reference write processing parameters at each circumferential position of the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters at each circumferential position on the track to write processing parameters at each circumferential position (hereinafter, it may also be referred to as corrected write processing parameters). The access processing control unit 620 sets each corrected write processing parameter corresponding to each circumferential position of the track. The access processing control unit 620 may also store each corrected write processing parameter at each circumferential position of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0068] The changes (or measured changes) in the evaluation metrics on the predetermined track include the evaluation metrics (or measured evaluation metrics) at each circumferential position of the predetermined track. The changes in the write processing parameter corrections on the predetermined track include the write processing parameter corrections at each circumferential position of the predetermined track. The changes in the write processing parameters on the predetermined track include the write processing parameters at each circumferential position of the predetermined track. The changes in the corrected write processing parameters on the predetermined track include the corrected write processing parameters at each circumferential position of the predetermined track.

[0069] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency at each circumferential position on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each BER at each circumferential position of the track (hereinafter, there may also be a case referred to as measured BER). The access processing control unit 620 calculates, based on the measured BER at each circumferential position of the track, the amount of change in recording density at each circumferential position relative to each reference recording density, each reference recording current, each reference heater setting value, each reference transport speed, or each reference recording frequency at each circumferential position on the track (hereinafter, it may also be called recording density correction amount or recording density change amount), the amount of change in recording current (hereinafter, it may also be called recording current correction amount or recording current change amount), the amount of change in heater setting value (hereinafter, it may also be called heater setting correction amount or heater setting change amount), the amount of change in transport speed (hereinafter, it may also be called transport speed correction amount or transport speed change amount), or the amount of change in recording frequency (hereinafter, it may also be called recording frequency correction amount or recording frequency change amount) for adjusting the measured BER at each circumferential position of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) correction amounts for recording density, recording current, heater setting, transport speed, or recording frequency at each circumferential position on the track to each reference recording density, reference recording current, heater setting, transport speed, or recording frequency. As a result, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency at each circumferential position on the track to each recording density (hereinafter, also referred to as corrected recording density), recording current (hereinafter, also referred to as corrected recording current), heater setting (hereinafter, also referred to as corrected heater setting), transport speed (hereinafter, also referred to as corrected transport speed), or recording frequency (hereinafter, also referred to as corrected recording frequency) at each circumferential position on the track. The access processing control unit 620 sets the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency corresponding to each circumferential position of the track. The access processing control unit 620 may also maintain the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency at each circumferential position of the predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0070] Variations in BER (or measured BER) on a predetermined track include the BER (or measured BER) at each circumferential position of the predetermined track. Variations in recording density on a predetermined track include the recording density at each circumferential position of the predetermined track. Variations in recording density correction on a predetermined track include the recording density correction at each circumferential position of the predetermined track. Variations in corrected recording density on a predetermined track include the corrected recording density at each circumferential position of the predetermined track. Variations in recording current on a predetermined track include the recording current at each circumferential position of the predetermined track. Variations in recording current correction on a predetermined track include the recording current correction at each circumferential position of the predetermined track. Variations in corrected recording current on a predetermined track include the corrected recording current at each circumferential position of the predetermined track. Variations in heater setting on a predetermined track include the heater setting at each circumferential position of the predetermined track. Variations in heater setting correction on a predetermined track include the heater setting correction at each circumferential position of the predetermined track. Variations in the correction heater setting value on the predetermined track include the correction heater setting value at each circumferential position of the predetermined track. Variations in the transport speed on the predetermined track include the transport speed at each circumferential position of the predetermined track. Variations in the transport speed correction amount on the predetermined track include the transport speed correction amount at each circumferential position of the predetermined track. Variations in the corrected transport speed on the predetermined track include the corrected transport speed at each circumferential position of the predetermined track. Variations in the recording frequency on the predetermined track include the recording frequency at each circumferential position of the predetermined track. Variations in the recording frequency correction amount on the predetermined track include the recording frequency correction amount at each circumferential position of the predetermined track. Variations in the corrected recording frequency on the predetermined track include the corrected recording frequency at each circumferential position of the predetermined track.

[0071] The access processing control unit 620 sets the write processing parameters of each partitioned region on a predetermined track as reference write processing parameters and measures each measured evaluation index of each partitioned region of the track. Based on the measured evaluation indexes of each partitioned region of the track, the access processing control unit 620 calculates a correction amount for each partitioned region's write processing parameters relative to the reference write processing parameters of each partitioned region of the track, used to adjust the measured evaluation indexes of each partitioned region of the track to uniformity or suppression. The access processing control unit 620 adds (or subtracts) the correction amount for each partitioned region's write processing parameters to the reference write processing parameters of each partitioned region of the track. Thus, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of each partitioned region of the track to corrected write processing parameters for each partitioned region. The access processing control unit 620 sets corrected write processing parameters corresponding to each partitioned region of the track. The access processing control unit 620 can also store the correction write processing parameters of each partitioned area of ​​the predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0072] Changes in evaluation metrics (or measured evaluation metrics) on the predetermined track include all evaluation metrics (or measured evaluation metrics) for each sub-region of the predetermined track. Changes in write processing parameters on the predetermined track include all write processing parameters for each sub-region of the predetermined track. Changes in write processing parameter correction amounts on the predetermined track include all write processing parameter correction amounts for each sub-region of the predetermined track. Changes in corrected write processing parameters on the predetermined track include all corrected write processing parameters for each sub-region of the predetermined track.

[0073] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency of each segmented region on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each BER (hereinafter, also referred to as measured BER) of each segmented region of the track. Based on the measured measured BER of each segmented region of the track, the access processing control unit 620 calculates a correction amount for each recording density, each recording current, each heater setting, each transport speed, or each recording frequency of each segmented region on the track, relative to the reference recording density, each reference recording current, each reference heater setting value, each reference transport speed, or each reference recording frequency of each segmented region on the track, for adjusting the measured BER of each segmented region of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) correction amounts for the recording density, recording current, heater setting, transport speed, or recording frequency of each segmented region on the track to each reference recording density, reference recording current, heater setting, transport speed, or recording frequency. As a result, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each segmented region on the track to corrected recording density, corrected recording current, corrected heater setting, corrected transport speed, or corrected recording frequency for each segmented region on the track. The access processing control unit 620 sets corrected recording densities, corrected recording currents, corrected heater settings, corrected transport speeds, or corrected recording frequencies for each segmented region on the track. The access processing control unit 620 can also maintain each correction recording density, each correction recording current, each correction heater setting value, each correction transmission speed, or each correction recording frequency in each divided area of ​​the predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0074] Variations in BER (or measured BER) on a predetermined track include the BER (or measured BER) for each sub-region of the predetermined track. Variations in recording density on a predetermined track include the recording density for each sub-region of the predetermined track. Variations in recording density correction on a predetermined track include the recording density correction for each sub-region of the predetermined track. Variations in corrected recording density on a predetermined track include the corrected recording density for each sub-region of the predetermined track. Variations in recording current on a predetermined track include the recording current for each sub-region of the predetermined track. Variations in recording current correction on a predetermined track include the recording current correction for each sub-region of the predetermined track. Variations in corrected recording current on a predetermined track include the corrected recording current for each sub-region of the predetermined track. Variations in heater setting on a predetermined track include the heater setting for each sub-region of the predetermined track. Variations in heater setting correction on a predetermined track include the heater setting correction for each sub-region of the predetermined track. Variations in corrected heater setting on a predetermined track include the corrected heater setting for each sub-region of the predetermined track. Variations in transport speed on a predetermined track include the transport speeds of each division of the predetermined track. Variations in transport speed correction on a predetermined track include the transport speed corrections of each division of the predetermined track. Variations in corrected transport speed on a predetermined track include the corrected transport speeds of each division of the predetermined track. Variations in recording frequency on a predetermined track include the recording frequencies of each division of the predetermined track. Variations in corrected recording frequency on a predetermined track include the corrected recording frequencies of each division of the predetermined track.

[0075] The access processing control unit 620 sets the write processing parameters of each sector on a predetermined track as reference write processing parameters and measures the measured evaluation indices of each sector on that track. Based on the measured evaluation indices of each sector on that track, the access processing control unit 620 calculates the write processing parameter correction amount for each sector relative to the reference write processing parameters of each sector on that track, used to adjust the measured evaluation indices of each sector on that track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the correction amount for each sector to the reference write processing parameters of each sector on that track. Thus, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of each sector on that track to the write processing parameters of each sector (hereinafter, there may also be cases referred to as corrected write processing parameters). The access processing control unit 620 sets the corrected write processing parameters corresponding to each sector on that track. The access processing control unit 620 can also store the correction and write processing parameters of each sector of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0076] Changes in evaluation metrics (or measured evaluation metrics) on a predetermined track include all evaluation metrics (measured evaluation metrics) for each sector of the predetermined track. Changes in write processing parameters on a predetermined track include all write processing parameters for each sector of the predetermined track. Changes in write processing parameter correction amounts on a predetermined track include all write processing parameter correction amounts for each sector of the predetermined track. Changes in corrected write processing parameters on a predetermined track include all corrected write processing parameters for each sector of the predetermined track.

[0077] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency of each sector on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each measured BER of each sector of the track. Based on the measured BER of each sector of the track, the access processing control unit 620 calculates a correction amount for each sector, a correction amount for each recording density, a correction amount for each recording current, a correction amount for each heater setting, a correction amount for each transport speed, or a correction amount for each recording frequency of each sector on the track, relative to each reference recording density, each reference recording current, each reference heater setting value, each reference transport speed, or each reference recording frequency of each sector on the track, to make the measured BER of each sector of the track uniform. The access processing control unit 620 adds (or subtracts) corrections for the recording density, recording current, heater setting, transport speed, or recording frequency of each sector on the track to each reference recording density, reference recording current, heater setting, transport speed, or recording frequency of that sector. As a result, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, heater setting, transport speed, or recording frequency of each sector on the track to each recording density (hereinafter, also referred to as corrected recording density), recording current (hereinafter, also referred to as corrected recording current), heater setting (hereinafter, also referred to as corrected heater setting), transport speed (hereinafter, also referred to as corrected transport speed), or recording frequency (hereinafter, also referred to as corrected recording frequency) of that sector on the track. The access processing control unit 620 sets the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency corresponding to each sector of the track. The access processing control unit 620 may also store the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency of each sector of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0078] Variations in BER (or measured BER) on a predetermined track include the BER (or measured BER) of each sector on that predetermined track. Variations in recording density on a predetermined track include the recording density of each sector on that predetermined track. Variations in recording density correction on a predetermined track include the recording density correction of each sector on that predetermined track. Variations in corrected recording density on a predetermined track include the corrected recording density of each sector on that predetermined track. Variations in recording current on a predetermined track include the recording current of each sector on that predetermined track. Variations in recording current correction on a predetermined track include the recording current correction of each sector on that predetermined track. Variations in corrected recording current on a predetermined track include the corrected recording current of each sector on that predetermined track. Variations in heater settings on a predetermined track include the heater settings of each sector on that predetermined track. Variations in heater setting correction on a predetermined track include the heater setting correction of each sector on that predetermined track. Variations in corrected heater settings on a predetermined track include the corrected heater settings of each sector on that predetermined track. Variations in the transfer speed on a predetermined track include the transfer speed of each sector of the predetermined track. Variations in the transfer speed correction amount on a predetermined track include the transfer speed correction amount of each sector of the predetermined track. Variations in the corrected transfer speed on a predetermined track include the corrected transfer speed of each sector of the predetermined track. Variations in the recording frequency on a predetermined track include the recording frequency of each sector of the predetermined track. Variations in the recording frequency correction amount on a predetermined track include the recording frequency correction amount of each sector of the predetermined track. Variations in the corrected recording frequency on a predetermined track include the corrected recording frequency of each sector of the predetermined track.

[0079] The access processing control unit 620 sets the write processing parameters on a predetermined track as the reference write processing parameters and measures the variation of the measured evaluation index of that track. The access processing control unit 620 approximates the measured variation of the measured evaluation index of that track and calculates the approximate variation of the measured evaluation index of that track (hereinafter, there may also be a case referred to as the variation of the approximate evaluation index). The access processing control unit 620 corrects (or adjusts) the calculated variation of the approximate evaluation index of that track and calculates the corrected (or adjusted) variation of the approximate evaluation index of that track (hereinafter, there may also be a case referred to as the variation of the corrected evaluation index). Based on the calculated variation of the corrected evaluation index of that track, the access processing control unit 620 calculates a write processing parameter correction amount relative to the reference write processing parameters on that track, used to adjust the variation of the corrected evaluation index on that track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the variation of the write processing parameter correction amount to the reference write processing parameters on that track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of the track to a change in the corrected write processing parameters of the track. The access processing control unit 620 sets the change in the corrected write processing parameters for the track. The access processing control unit 620 may also store the change in the corrected write processing parameters on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0080] Furthermore, the access processing control unit 620, either idle or in real-time, sets the write processing parameters on a predetermined track as reference write processing parameters and measures the variation of the measured evaluation index of that track. The access processing control unit 620, either idle or in real-time, approximates the measured variation of the track's measured evaluation index and calculates the approximate variation of the track's approximate evaluation index. The access processing control unit 620, either idle or in real-time, corrects (or adjusts) the calculated variation of the track's approximate evaluation index and calculates the corrected (or adjusted) variation of the track's corrected evaluation index. Based on the calculated variation of the track's corrected evaluation index, the access processing control unit 620, either idle or in real-time, calculates a write processing parameter correction amount relative to the reference write processing parameters on that track to correct (or adjust) the variation of the corrected evaluation index to a uniform level. The access processing control unit 620, either idle or in real-time, adds (or subtracts) the variation of the write processing parameter correction amount to the reference write processing parameters on that track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of the track to the modified write processing parameters of the track, either when idle or in real time. The access processing control unit 620 sets the modified write processing parameters for the track, either when idle or in real time. Additionally, the access processing control unit 620 can also store the changes in the modified write processing parameters of each track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80, either when idle or in real time.

[0081] The access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures the variation in the measured BER of that track. The access processing control unit 620 approximates the measured variation in the measured BER of that track and calculates the approximate variation in the measured BER of that track (hereinafter, there may also be a case referred to as the approximate BER variation). The access processing control unit 620 corrects (or adjusts) the calculated approximate BER variation of that track and calculates the corrected (or adjusted) approximate BER variation of that track (hereinafter, there may also be a case referred to as the corrected BER variation). Based on the calculated change in the corrected BER of the track, the access processing control unit 620 calculates changes in recording density correction, recording current correction, heater setting correction, transport speed correction, or recording frequency correction relative to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of the track, for adjusting the change in the corrected BER of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the changes in recording density correction, recording current correction, heater setting correction, transport speed correction, or recording frequency correction to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of the track to the changes in the corrected recording density, corrected recording current, corrected heater setting, corrected transport speed, or corrected recording frequency of the track. The access processing control unit 620 sets corrections for changes in recording density, recording current, heater setting, transfer speed, or recording frequency for each track. The access processing control unit 620 can also store these corrections for changes in recording density, recording current, heater setting, transfer speed, or recording frequency for each track in a predetermined storage area, such as the system area 10b of disk 10 or the non-volatile memory 80.

[0082] For example, the access processing control unit 620 sets the recording density on a predetermined track as a reference recording density and measures the variation in the measured BER of that track. The access processing control unit 620 approximates the measured variation in the measured BER of the track and calculates the approximate BER for each circumferential position of the track. The access processing control unit 620 corrects (or adjusts) the calculated variation in the approximate BER of the track and calculates the corrected (or adjusted) variation in the track's BER. Based on the calculated variation in the corrected BER of the track, the access processing control unit 620 calculates the variation in the track's recording density correction amount relative to the reference recording density of the track, used to adjust the variation in the corrected BER of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the recording density correction amount for each circumferential position to the reference recording density of each circumferential position on the track. Thus, the access processing control unit 620 adds (or subtracts) the variation in the track's recording density correction amount to the reference recording density of the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density of the track to the change in the recording density correction amount of the track, and the change in the corrected recording density of the track. The access processing control unit 620 calculates the change in the time base generator (TBG) value (hereinafter, there is also a case referred to as the change in TBG value) corresponding to the change in the recording frequency (corrected recording frequency) proportional to the change in the corrected recording density on the track. The access processing control unit 620 sets the change in the TBG value for the track. The access processing control unit 620 may also maintain the change in the TBG value on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0083] The access processing control unit 620 sets each write processing parameter at each circumferential position on a predetermined track as a reference write processing parameter, and measures each measured evaluation index at each circumferential position of the track. The access processing control unit 620 approximates each measured evaluation index at each circumferential position of the track, and calculates each approximate evaluation index at each circumferential position of the track after approximation. The access processing control unit 620 corrects (or adjusts) each approximate evaluation index at each circumferential position of the track, and calculates each corrected evaluation index at each circumferential position of the track after correction (or adjustment). Based on the calculated corrected evaluation index at each circumferential position of the track, the access processing control unit 620 calculates each write processing parameter correction amount for each circumferential position relative to the reference write processing parameters at each circumferential position of the track, used to adjust each corrected evaluation index at each circumferential position of the track to uniformity or suppression. The access processing control unit 620 adds (or subtracts) the correction amount of each write processing parameter at each circumferential position on the track to the reference write processing parameters at each circumferential position. Thus, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters at each circumferential position on the track to corrected write processing parameters for each circumferential position. The access processing control unit 620 sets each corrected write processing parameter corresponding to each circumferential position of the track. The access processing control unit 620 may also store each corrected write processing parameter at each circumferential position of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0084] The changes in the approximate evaluation indexes on the predetermined track include the approximate evaluation indexes for each circumferential position of the predetermined track. The changes in the corrected evaluation indexes on the predetermined track include the corrected evaluation indexes for each circumferential position of the predetermined track.

[0085] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency at each circumferential position on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each measured BER at each circumferential position of the track. The access processing control unit 620 approximates each measured BER at each circumferential position of the track and calculates each approximate BER at each circumferential position of the track. The access processing control unit 620 corrects (or adjusts) each approximate BER at each circumferential position of the track and calculates each corrected (or adjusted) BER at each circumferential position of the track. Based on the calculated correction BER at each circumferential position on the track, the access processing control unit 620 calculates a correction amount for each circumferential position of the track, relative to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency, for adjusting the correction BER at each circumferential position of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the correction amounts for each circumferential position of the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transfer speed, or reference recording frequency at each circumferential position on the track to corrected recording densities, corrected recording currents, corrected heater settings, corrected transfer speeds, or corrected recording frequencies at each circumferential position on the track. The access processing control unit 620 sets corrected recording densities, corrected recording currents, corrected heater settings, corrected transfer speeds, or corrected recording frequencies corresponding to each circumferential position on the track. The access processing control unit 620 may also maintain the corrected recording densities, corrected recording currents, corrected heater settings, corrected transfer speeds, or corrected recording frequencies at each circumferential position on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0086] Variations in the approximate BER on a predetermined track include the approximate BER at each circumferential position of the predetermined track. Variations in the corrected BER on a predetermined track include the corrected BER at each circumferential position of the predetermined track.

[0087] For example, the access processing control unit 620 sets the recording density at each circumferential position on a predetermined track as a reference recording density and measures the measured BER at each circumferential position of the track. The access processing control unit 620 approximates the measured BER at each circumferential position of the track and calculates the approximate BER at each circumferential position of the track. The access processing control unit 620 corrects (or adjusts) the calculated approximate BER at each circumferential position of the track and calculates the corrected BER at each circumferential position of the track. Based on the calculated corrected BER at each circumferential position of the track, the access processing control unit 620 calculates a recording density correction amount at each circumferential position relative to the reference recording density at each circumferential position of the track, used to adjust the corrected BER at each circumferential position of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the recording density correction amount at each circumferential position to the reference recording density at each circumferential position of the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density at each circumferential position on the track to a corrected recording density at each circumferential position. The access processing control unit 620 calculates the TBG value at each circumferential position, which is proportional to the corrected recording density at each circumferential position on the track, and assigns it to the corresponding TBG value at each circumferential position on the track. The access processing control unit 620 may also store the TBG values ​​at each circumferential position on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0088] The variation of TBG value on the predetermined track includes the TBG value at each circumferential position of the predetermined track.

[0089] The access processing control unit 620 sets the write processing parameters of each partitioned region on a predetermined track as reference write processing parameters and measures each measured evaluation index of each partitioned region of the track. The access processing control unit 620 approximates the measured evaluation indexes of each partitioned region of the track and calculates the approximate evaluation indexes of each partitioned region of the track. The access processing control unit 620 corrects (or adjusts) the calculated approximate evaluation indexes of each partitioned region of the track and calculates the corrected (or adjusted) evaluation indexes of each partitioned region of the track. Based on the calculated corrected evaluation indexes of each partitioned region of the track, the access processing control unit 620 calculates the write processing parameter correction amount for each partitioned region relative to the reference write processing parameters of each partitioned region on the track, used to adjust the corrected evaluation indexes of each partitioned region of the track to uniformity or suppression. The access processing control unit 620 adds (or subtracts) the write processing parameter correction amount for each partitioned region to the reference write processing parameters of each partitioned region on the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of each partitioned region on the track to the corrected write processing parameters of each partitioned region. The access processing control unit 620 sets the corrected write processing parameters corresponding to each partitioned region of the track. The access processing control unit 620 may also store the corrected write processing parameters of each partitioned region of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0090] Changes in the approximate evaluation indexes on the predetermined track include the approximate evaluation indexes for each sub-region of the predetermined track. Changes in the revised evaluation indexes on the predetermined track include the revised evaluation indexes for each sub-region of the predetermined track.

[0091] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency of each segmented region on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each measured BER of each segmented region of the track. The access processing control unit 620 approximates each measured BER of each segmented region of the track and calculates each approximate BER of each segmented region of the track after approximation. The access processing control unit 620 corrects (or adjusts) each approximate BER of each segmented region of the track and calculates each corrected BER of each segmented region of the track after correction (or adjustment). Based on the calculated correction BER of each segmented region on the track, the access processing control unit 620 calculates a correction amount for each recording density, recording current, heater setting, transport speed, or recording frequency relative to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each segmented region on the track, used to adjust the correction BER of each segmented region of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the correction amounts for each recording density, recording current, heater setting, transport speed, or recording frequency of each segmented region on the track to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each segmented region. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transfer speed, or reference recording frequency of each segmented region on the track to the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency of each segmented region on the track. The access processing control unit 620 sets the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency corresponding to each circumferential position on the track. The access processing control unit 620 may also maintain the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency of each segmented region on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0092] Variations in the approximate BER on a predetermined track include the approximate BER at each circumferential position of the predetermined track. Variations in the corrected BER on a predetermined track include the corrected BER at each circumferential position of the predetermined track.

[0093] For example, the access processing control unit 620 sets the recording density of each segmented region on a predetermined track as a reference recording density and measures the measured BER of each segmented region on that track. The access processing control unit 620 approximates the measured BER of each segmented region on that track and calculates the approximate BER of each segmented region on that track. The access processing control unit 620 corrects (or adjusts) the calculated approximate BER of each segmented region on that track and calculates the corrected BER of each segmented region on that track. Based on the calculated corrected BER of each segmented region on that track, the access processing control unit 620 calculates a recording density correction amount for each segmented region relative to the reference recording density of each segmented region on that track, used to adjust the corrected BER of each segmented region on that track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the recording density correction amount for each segmented region to the reference recording density of each segmented region on that track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density of each partitioned region on the track to the corrected recording density of each partitioned region. The access processing control unit 620 calculates the TBG value of each partitioned region, which is proportional to the corrected recording density of each partitioned region on the track. The access processing control unit 620 sets the TBG value corresponding to each partitioned region of the track. The access processing control unit 620 may also store the TBG values ​​of each partitioned region of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0094] The variation in TBG values ​​on a predetermined track includes the TBG values ​​of each division of the predetermined track.

[0095] The access processing control unit 620 sets the write processing parameters of each sector on a predetermined track as reference write processing parameters and measures the measured evaluation indexes of each sector on that track. The access processing control unit 620 approximates the measured evaluation indexes of each sector on that track and calculates the approximate evaluation indexes of each sector on that track. The access processing control unit 620 corrects (or adjusts) the calculated approximate evaluation indexes of each sector on that track and calculates the corrected (or adjusted) evaluation indexes of each sector on that track. Based on the calculated corrected evaluation indexes of each sector on that track, the access processing control unit 620 calculates the write processing parameter correction amount for each sector relative to the reference write processing parameters of each sector on that track, used to adjust the corrected evaluation indexes of each sector on that track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the write processing parameter correction amount for each sector to the reference write processing parameters of each sector on that track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of each sector on the track to the corrected write processing parameters of each sector. The access processing control unit 620 sets the corrected write processing parameters corresponding to each sector of the track. The access processing control unit 620 may also store the corrected write processing parameters of each sector of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0096] Changes in the approximate evaluation indexes on the predetermined track include the approximate evaluation indexes for each sector of the predetermined track. Changes in the corrected evaluation indexes on the predetermined track include the corrected evaluation indexes for each sector of the predetermined track.

[0097] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency of each sector on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each measured BER of each sector of that track. The access processing control unit 620 approximates each measured BER of each sector of that track and calculates each approximate BER of each sector of that track. The access processing control unit 620 corrects (or adjusts) each approximate BER of each sector of that track and calculates each corrected BER of each sector of that track. Based on the calculated correction BER of each sector on the track, the access processing control unit 620 calculates the correction amounts for each sector of the track relative to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each sector on the track, used to adjust the correction BER of each sector of the track to be uniform or suppressed. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transfer speed, or reference recording frequency of each sector on the track to the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency of each sector on the track. The access processing control unit 620 sets the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency corresponding to each sector on the track. The access processing control unit 620 may also store the corrected recording density, corrected recording current, corrected heater setting, corrected transfer speed, or corrected recording frequency of each sector on a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0098] The variation in approximate BER on a predetermined track includes the approximate BER for each sector of the predetermined track. The variation in corrected BER on a predetermined track includes the corrected BER for each sector of the predetermined track.

[0099] For example, the access processing control unit 620 sets the recording density of each sector on a predetermined track as a reference recording density and measures the measured BER of each sector on that track. The access processing control unit 620 approximates the measured BER of each sector on that track and calculates the approximate BER of each sector on that track. The access processing control unit 620 corrects (or adjusts) the calculated approximate BER of each sector on that track and calculates the corrected BER of each sector on that track. Based on the calculated corrected BER of each sector on that track, the access processing control unit 620 calculates a recording density correction amount for each sector relative to the reference recording density of each sector on that track, used to adjust the corrected BER of each sector on that track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the recording density correction amount for each sector to the reference recording density of each sector on that track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density of each sector on the track to the corrected recording density of each sector. The access processing control unit 620 calculates the TBG value of each sector, which is proportional to the corrected recording density of each sector on the track. The access processing control unit 620 sets the TBG value corresponding to each sector of the track. The access processing control unit 620 may also store the TBG values ​​of each sector of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and the non-volatile memory 80.

[0100] The variation in TBG value on a predetermined track includes the TBG value of each sector of the predetermined track.

[0101] The access processing control unit 620 sets each write processing parameter at each circumferential position on a predetermined track as a reference write processing parameter, and measures each measured evaluation index at each circumferential position of the track. The access processing control unit 620 approximates each measured evaluation index at each circumferential position of the track, and calculates each approximate evaluation index at each circumferential position of the track after approximation. The access processing control unit 620 corrects (or adjusts) each approximate evaluation index at each circumferential position of the track, and calculates each corrected evaluation index for each segmented region of the track after correction (or adjustment). Based on the calculated corrected evaluation indexes for each segmented region of the track, the access processing control unit 620 calculates a correction amount for each write processing parameter of each segmented region relative to the reference write processing parameters of each segmented region on the track, used to adjust the correction evaluation indexes of each segmented region of the track to uniformity or suppression. The access processing control unit 620 adds (or subtracts) the correction amount for each write processing parameter of each segmented region to the reference write processing parameters of each segmented region on the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference write processing parameters of each partitioned region on the track to the corrected write processing parameters of each partitioned region. The access processing control unit 620 sets the corrected write processing parameters corresponding to each partitioned region of the track. The access processing control unit 620 may also store the corrected write processing parameters of each partitioned region of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0102] For example, the access processing control unit 620 sets each recording density, each recording current, each heater setting value, each transport speed, or each recording frequency at each circumferential position on a predetermined track as a reference recording density, reference recording current, reference heater setting value, reference transport speed, or reference recording frequency, and measures each measured BER at each circumferential position of the track. The access processing control unit 620 approximates each measured BER at each circumferential position of the track and calculates each approximate BER at each circumferential position of the track after approximation. The access processing control unit 620 corrects (or adjusts) each approximate BER at each circumferential position of the track and calculates each corrected BER for each divided region of the track after correction (or adjustment). Based on the calculated correction BER of each segmented region of the track, the access processing control unit 620 calculates correction amounts for each recording density, recording current, heater setting, transport speed, or recording frequency relative to the reference recording density, reference recording current, reference heater setting, transport speed, or recording frequency of each segmented region on the track. The access processing control unit 620 adds (or subtracts) these correction amounts to the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each segmented region on the track. Thus, the access processing control unit 620 corrects (or adjusts) the reference recording density, reference recording current, reference heater setting, reference transport speed, or reference recording frequency of each segmented region on the track to the corrected recording density, corrected recording current, corrected heater setting, corrected transport speed, or corrected recording frequency of each segmented region. The access processing control unit 620 sets the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency corresponding to each division region of the track. The access processing control unit 620 may also store the correction recording density, correction recording current, correction heater setting value, correction transfer speed, or correction recording frequency in each division region of the predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0103] For example, the access processing control unit 620 sets the recording density at each circumferential position on a predetermined track as a reference recording density and measures the measured BER at each circumferential position of the track. The access processing control unit 620 approximates the measured BER at each circumferential position of the track and calculates the approximate BER at each circumferential position of the track. The access processing control unit 620 corrects (or adjusts) the calculated approximate BER at each circumferential position of the track and calculates the corrected BER for each segmented region of the track. Based on the calculated corrected BER for each segmented region of the track, the access processing control unit 620 calculates a recording density correction amount for each segmented region relative to the reference recording density of each segmented region of the track, used to adjust the corrected BER of each segmented region of the track to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the recording density correction amount for each segmented region to the reference recording density of each segmented region of the track. Therefore, the access processing control unit 620 corrects (or adjusts) the reference recording density of each partitioned region on the track to the corrected recording density of each partitioned region. The access processing control unit 620 calculates the TBG value of each partitioned region on the track. The access processing control unit 620 sets the TBG value corresponding to each partitioned region on the track. The access processing control unit 620 may also store the TBG values ​​of each partitioned region of a predetermined track in a predetermined storage area, such as the system area 10b of disk 10 and non-volatile memory 80.

[0104] Figure 5 This is a schematic diagram illustrating an example of the variation of the measured evaluation index MBL5, the variation of the approximate evaluation index ABL5, and the variation of the corrected evaluation index CBL5 for the circumferential position of a predetermined magnetic track. Figure 5 In the diagram, the vertical axis represents the BER (Breakpoint Requirement), and the horizontal axis represents the circumferential position. Figure 5 On the vertical axis, BER increases as it moves toward the front of the arrow and decreases as it moves toward the opposite side of the arrow. Figure 5 The circumferential position of the horizontal axis includes the circumferential position where data writing begins on the predetermined track (hereinafter, it may also be called the start position) and the circumferential position where data writing ends on the predetermined track (hereinafter, it may also be called the end position). The start position and the end position may be the same or different in the circumferential direction of the predetermined track. Figure 5The diagram shows variations in measured evaluation indices for circumferential positions on a predetermined track (hereinafter, also simply referred to as variations in measured evaluation indices), such as variations in measured BER for circumferential positions (hereinafter, also simply referred to as variations in measured BER) MBL5; variations in approximate evaluation indices for circumferential positions on a predetermined track (hereinafter, also simply referred to as variations in approximate evaluation indices), such as variations in approximate BER for circumferential positions (hereinafter, also simply referred to as variations in approximate BER) ABL5; and variations in corrected evaluation indices for circumferential positions on a predetermined track (hereinafter, also simply referred to as variations in corrected evaluation indices), such as variations in corrected BER for circumferential positions (hereinafter, also simply referred to as variations in corrected BER) CBL5. Additionally, in Figure 5 The front side of the horizontal axis shows the maximum (Max) and average (Ave.) of the measured BER variation, the maximum (Max) and average (Ave.) of the approximate BER variation, and the maximum (Max) and average (Ave.) of the corrected BER variation.

[0105] exist Figure 6 In the example shown, the access processing control unit 620 sets the recording density of each circumferential position on a predetermined track, such as the track currently being accessed (hereinafter, there may also be a case called the track on-track), as the reference recording density, measures each measured BER at each circumferential position of the track on-track, and obtains the variation MBL5 of the measured BER of the track on-track.

[0106] The access processing control unit 620 uses the formula (1) described below to approximate each measured BER of each circumferential position of the track, calculates each approximate BER of each circumferential position of the track after approximation, and obtains the variation ABL5 of the approximate BER of the track.

[0107] ya=a×cоs(px1+b)+ca(1)

[0108] Here, ya is the approximate BER, p is the coefficient, x1 is the measured BER, a is the coefficient, b is the coefficient, and ca is the average value of the variation of the approximate BER of the predetermined track ABL5.

[0109] The access processing control unit 620 uses the formula (2) described below to correct (or adjust) each approximate BER of each circumferential position of the track, calculates each corrected BER of each circumferential position of the track after correction (or adjustment), and obtains the change CBL5 of the corrected BER of the track.

[0110] yc=x+cv (2)

[0111] Here, yc is the corrected BER, and cv is the correction amount. The correction amount cv can be calculated using the following formula (3).

[0112] cv=x2-ca (3)

[0113] Here, x2 is the approximate BER.

[0114] Figure 6 This is a schematic diagram illustrating an example of the variation CBL6 of the correction evaluation index for circumferential position and the variation CPL6 of the correction write processing parameter in this embodiment. Figure 6 In the diagram, the vertical axis represents BER and write processing parameters, and the horizontal axis represents the circumferential position. Figure 6 In the diagram, BER increases as it moves towards the tip of the larger arrow and decreases as it moves towards the tip of the smaller arrow. Figure 6 In the text, the write processing parameters increase as you move towards the front of the larger arrow and decrease as you move towards the front of the smaller arrow. Figure 6 The circumferential position of the horizontal axis includes the start position and the end position. Figure 6 The diagram shows the following: reference write processing parameters, such as reference recording density DPL6; variations in corrected write processing parameters for circumferential position (hereinafter also referred to as variations in corrected write processing parameters), such as variations in corrected recording density for circumferential position (hereinafter also referred to as variations in corrected recording density) CPL6; variations in corrected evaluation index (or measured evaluation index) for circumferential position (hereinafter also referred to as variations in corrected evaluation index (or measured evaluation index)), such as variations in corrected BER (or measured BER) for circumferential position (hereinafter also referred to as variations in corrected BER (or measured BER)) MBL6; and variations in evaluation index for circumferential position corresponding to variations in corrected write processing parameters (hereinafter also referred to as variations in suppression evaluation index), such as variations in measured BER for circumferential position corresponding to the variation in corrected recording density CPL6 (hereinafter also referred to as variations in suppression BER) SBL6.

[0115] exist Figure 6In the example shown, the access processing control unit 620 sets the recording density on the current track as the reference recording density and measures the variation in BER (bit difference) MBL6 on the current track. Based on the measured variation in BER MBL6, the access processing control unit 620 calculates a change in the recording density correction amount on the current track to adjust the variation in BER MBL6 to be uniform or suppressed. The access processing control unit 620 adds (or subtracts) the change in recording density correction amount to the reference recording density on the current track. Thus, the access processing control unit 620 corrects (or adjusts) the reference recording density DPL6 on the current track to the change in corrected recording density CPL6 on the current track. The access processing control unit 620 sets the change in corrected recording density CPL6 on the current track. Figure 6 As shown, on the track, by setting the change in recording density CPL6, the change in measured BER MBL6 is suppressed to the change in BER SBL6.

[0116] exist Figure 7 In the example shown, the access processing control unit 620 sets each recording density on the current track as a reference recording density DPL6 and measures the variation in the measured BER of the current track. The access processing control unit 620 approximates the measured variation in the measured BER of the current track and calculates the approximate variation in the BER of the current track. The access processing control unit 620 corrects (or adjusts) the calculated variation in the approximate BER of the current track and calculates the corrected (or adjusted) variation in the corrected BER of the current track MBL6. Based on the calculated variation in the corrected BER of the current track MBL6, the access processing control unit 620 calculates a change in the recording density correction amount used to adjust the variation in the corrected BER of the current track MBL6 to uniformity or suppression. The access processing control unit 620 adds (or subtracts) the change in the recording density correction amount to the reference recording density of the current track. Thus, the access processing control unit 620 corrects (or adjusts) the reference recording density of the current track to the variation in the corrected recording density of the current track CPL6. The access processing control unit 620 sets a correction recording density variation CPL6 for the current track. For example... Figure 7 As shown, on the track, by setting the change in modified recording density CPL6, the change in modified BER MBL6 is suppressed to the change in suppressed BER SBL6.

[0117] Figure 7 This is a schematic diagram illustrating an example of the variation in BER (BER) of a predetermined track for a circumferential position when edge writing has been performed. Figure 7 In the diagram, the vertical axis represents the BER (Breakpoint Requirement), and the horizontal axis represents the circumferential position. Figure 7 In the diagram, BER increases as it moves toward the front of the larger arrow and decreases as it moves toward the front of the smaller arrow.Figure 7 The circumferential position of the horizontal axis includes the start position and the end position. Figure 7 The diagram illustrates changes in modified evaluation metrics (or measured evaluation metrics), such as changes in modified BER (or measured BER) MBL6, and changes in suppression evaluation metrics, such as changes in suppressed BER SBL6. Additionally, Figure 7 The diagram shows the changes in the evaluation index for the circumferential position of the track where the track containing the modified evaluation index (or measured evaluation index), such as the change in modified BER (or measured BER), are shown in DFBL7 when the track containing the modified evaluation index (or measured BER) has been edge-written (hereinafter, there is also a case where the change is simply referred to as the change in the initial edge evaluation index). For example, the change in BER for the circumferential position is shown in CFBL7 when the track containing the modified evaluation index (or measured BER), such as the change in modified BER, are shown in CFBL7 when the track containing the modified evaluation index (or measured BER) has been edge-written (hereinafter, there is also a case where the change is simply referred to as the change in modified edge evaluation index).

[0118] exist Figure 7 In the example shown, the access processing control unit 620 measures the variation of the measured BER (MBL6) on the track where a reference recording density (DPL6) is set. When the access processing control unit 620 performs an edge write to an adjacent track of the track where the measured BER variation (MBL6) is located, it measures the variation of the initial edge BER (DFBL7).

[0119] exist Figure 7 In the example shown, when the access processing control unit 620 sets a change in the modified recording density CPL6 for the current track, it measures the change in the suppressed BER SBL6 on the current track. When the access processing control unit 620 writes to an adjacent track of the current track with the changed BER SBL6, it measures the change in the modified edge BER CFBL7.

[0120] like Figure 7 As shown, the change in edge BER CFBL7 after correction is greater than the change in edge BER DFBL7 of the initial edge BER. Figure 8In the example shown, a portion of the corrected edge BER change CFBL7 is larger than a portion of the initial edge BER change DFBL7, and a portion of the corrected edge BER change CFBL7 is smaller than a portion of the initial edge BER change DFBL. Therefore, compared to the case where a write was made to a track adjacent to the track containing the measured BER change MBL6, the write to a track adjacent to the track containing the suppressed BER change SBL6 may result in a larger effect (Adjacent Track Interference: ATI) from the first 15 of the predetermined region of the track, and a smaller ATI from the first 15 of other regions of the track. In other words, compared to the case where a write was made to a track adjacent to the track containing the suppressed BER change SBL6, the write to a track adjacent to the track containing the measured BER change MBL6 may result in data in the predetermined region of the track being more prone to degradation, while data in other regions of the track may be less prone to degradation. In other words, compared to writing data to an adjacent track of the track after the write processing parameters have been corrected, writing data to an adjacent track of the track without correction may result in data degradation in a predetermined area of ​​the track, while data in other areas of the track may not degrade as easily.

[0121] The refresh control unit 630 counts the number of times data is written (hereinafter, also referred to as the number of writes). The refresh control unit 630 also counts the number of times data is written to a region (hereinafter, also referred to as a proximity region) located within a predetermined radius from the target region (hereinafter, also referred to as the target region). For example, the refresh control unit 630 counts the number of times data is written to a proximity region (hereinafter, also referred to as an outer-direction proximity region) located within a predetermined radius from the target region in the outward direction. Additionally, the refresh control unit 630 counts the number of times data is written to a proximity region (hereinafter, also referred to as an inner-direction proximity region) located within a predetermined radius from the target region in the inward direction. The refresh control unit 630 can also store the number of writes as a table 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.

[0122] When the refresh control unit 630 writes data to a proximity region located within a predetermined radius from the target region, it increases the number of writes to the proximity region by a predetermined value. For example, when writing data to a proximity region located within a predetermined radius from the target region, the refresh control unit 630 increases the number of writes to the proximity region by 1. When the refresh control unit 630 writes data to a proximity region in the outward direction, it increases the number of writes to the proximity region in the outward direction by a predetermined value. For example, when writing data to a proximity region in the outward direction, the refresh control unit 630 increases the number of writes to the proximity region in the outward direction by 1. When the refresh control unit 630 writes data to a proximity region in the inward direction, it increases the number of writes to the proximity region in the inward direction by a predetermined value. For example, when writing data to a proximity region in the inward direction, the refresh control unit 630 increases the number of writes to the proximity region in the inward direction by 1.

[0123] The refresh control unit 630 counts the number of times data is written to a region adjacent to the object region in the radial direction (hereinafter also referred to as an adjacent region). For example, the refresh control unit 630 counts the number of times data is written to an adjacent region that is adjacent to the object region in the outer direction (hereinafter also referred to as an outer direction adjacent region). Additionally, for example, the refresh control unit 630 counts the number of times data is written to an adjacent region that is adjacent to the object region in the inner direction (hereinafter also referred to as an inner direction adjacent region).

[0124] When the refresh control unit 630 writes data to an adjacent region located in the radial direction of the target region, it increases the number of writes to the adjacent region by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent region located in the radial direction of the target region, it increases the number of writes to the adjacent region by 1 (increment). When the refresh control unit 630 writes data to an adjacent region in the outward direction, it increases the number of writes to the adjacent region in the outward direction (outward write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent region in the outward direction, it increases the number of writes to the adjacent region in the outward direction by 1 (increment). When the refresh control unit 630 writes data to an adjacent region in the inward direction, it increases the number of writes to the adjacent region in the inward direction (inward write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent region in the inward direction, it increases the number of writes to the adjacent region in the inward direction by 1 (increment).

[0125] The refresh control unit 630 counts the number of times data is written to a region located within a predetermined radius in the radial direction of the region to which the object is defined (hereinafter, there may also be a region near the object region). For example, the refresh control unit 630 counts the number of times data is written to a region located within a predetermined radius in the outer direction of the object region. Additionally, the refresh control unit 630 counts the number of times data is written to a region located within a predetermined radius in the inner direction of the object region.

[0126] When the refresh control unit 630 writes data to a near-divided region located within a predetermined radius from the object's partitioned region, it increases the number of writes to the near-divided region by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a near-divided region located within a predetermined radius from the object's partitioned region, it increases the number of writes to the near-divided region by 1 (increment). When the refresh control unit 630 writes data to a near-divided region in the outer direction, it increases the number of writes to the near-divided region in the outer direction (outer direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a near-divided region in the outer direction, it increases the number of writes to the near-divided region in the outer direction (outer direction write count) by 1 (increment). When the refresh control unit 630 writes data to a near-divided region in the inner direction, it increases the number of writes to the near-divided region in the inner direction (inner direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a near-divided region in the inner direction, it increases the number of writes to the near-divided region in the inner direction (inner direction write count) by 1 (increment).

[0127] The refresh control unit 630 counts the number of times data is written to a partitioned region that is radially adjacent to the object partitioned region (hereinafter also referred to as an adjacent partitioned region). For example, the refresh control unit 630 counts the number of times data is written to an adjacent partitioned region that is radially adjacent to the object partitioned region (hereinafter also referred to as an outer-direction adjacent partitioned region). Additionally, for example, the refresh control unit 630 counts the number of times data is written to an adjacent partitioned region that is radially adjacent to the object partitioned region (hereinafter also referred to as an outer-direction adjacent partitioned region).

[0128] When the refresh control unit 630 writes data to an adjacent partitioned region located in the radial direction of the object partitioned region, it increases the number of writes to the adjacent partitioned region by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent partitioned region located in the radial direction of the object partitioned region, it increases the number of writes to the adjacent partitioned region by 1 (increment). When the refresh control unit 630 writes data to an adjacent partitioned region in the outward direction, it increases the number of writes to the adjacent partitioned region in the outward direction (outward write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent partitioned region in the outward direction, it increases the number of writes to the adjacent partitioned region in the outward direction (outward write count) by 1 (increment). When the refresh control unit 630 writes data to an adjacent partitioned region in the inward direction, it increases the number of writes to the adjacent partitioned region in the inward direction (inward write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent partitioned region in the inward direction, it increases the number of writes to the adjacent partitioned region in the inward direction (inward write count) by 1 (increment).

[0129] The refresh control unit 630 counts the number of times data is written to sectors located within a predetermined radius from the target sector (hereinafter also called "target sector") (hereinafter also called "nearby sector"). For example, the refresh control unit 630 counts the number of times data is written to nearby sectors located within a predetermined radius from the target sector (hereinafter also called "outer-direction near sector"). Additionally, the refresh control unit 630 counts the number of times data is written to nearby sectors located within a predetermined radius from the target sector (hereinafter also called "outer-direction near sector"). Furthermore, sectors that cause bleeding, leakage magnetic fields, or other effects on the target area when data is written can be detected during the manufacturing stage, and these detected sectors can be designated as proximity sectors. Alternatively, sectors that cause bleeding, leakage magnetic fields, or other effects on the target area when data is written can be detected during the operation processing stage, and these detected sectors can be designated as proximity sectors.

[0130] When the refresh control unit 630 writes data to a nearby sector located within a predetermined radius from the target sector, it increases the number of writes to the nearby sector by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a nearby sector located within a predetermined radius from the target sector, it increases the number of writes to the nearby sector by 1 (increment). When the refresh control unit 630 writes data to a nearby sector in the outer direction, it increases the number of writes to the nearby sector in the outer direction (outer direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a nearby sector in the outer direction, it increases the number of writes to the nearby sector in the outer direction (outer direction write count) by 1 (increment). When the refresh control unit 630 writes data to a nearby sector in the inner direction, it increases the number of writes to the nearby sector in the inner direction (inner direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to a nearby sector in the inner direction, it increases the number of writes to the nearby sector in the inner direction (inner direction write count) by 1 (increment).

[0131] The refresh control unit 630 counts the number of times data is written to adjacent sectors (hereinafter also referred to as adjacent sectors) in the radial direction of the target sector. For example, the refresh control unit 630 counts the number of times data is written to adjacent sectors (hereinafter also referred to as outer-direction adjacent sectors) in the outer direction of the target sector. Additionally, the refresh control unit 630 counts the number of times data is written to adjacent sectors (hereinafter also referred to as inner-direction adjacent sectors) in the inner direction of the target sector.

[0132] When the refresh control unit 630 writes data to an adjacent sector in the radial direction of the target sector, it increases the number of adjacent sector writes by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an adjacent sector in the radial direction of the target sector, it increases the number of adjacent sector writes by 1 (increment). When the refresh control unit 630 writes data to an outer adjacent sector, it increases the number of outer adjacent sector writes (outer direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an outer adjacent sector, it increases the number of outer adjacent sector writes (outer direction write count) by 1 (increment). When the refresh control unit 630 writes data to an inner adjacent sector, it increases the number of inner adjacent sector writes (inner direction write count) by a predetermined value (increment). For example, when the refresh control unit 630 writes data to an inner adjacent sector, it increases the number of inner adjacent sector writes (inner direction write count) by 1 (increment).

[0133] The refresh control unit 630 performs a process of rewriting data identical to data written to the object area back to the object area (hereinafter, this may also be referred to as rewriting, rewriting processing, refresh, or refresh processing), or a process of overwriting or rewriting data to the object area (hereinafter, this may also be referred to as overwriting processing, rewriting processing, rewriting, rewriting processing, refresh, or refresh processing). Hereinafter, the rewriting process, overwriting process, or rewriting process may be collectively referred to as rewriting, rewriting processing, refresh, or refresh processing. "Overwriting" includes "writing data on data written to a predetermined position in a predetermined area" and "writing data at the same position in the same area as data written to a predetermined position in a predetermined area."

[0134] The refresh control unit 630 has a threshold (hereinafter also referred to as the refresh threshold) for the number of write operations performed on a predetermined area. The refresh threshold is equivalent to the number of write operations performed on the area in the radial direction of the predetermined area when the data in the predetermined area is subjected to an ATI greater than a specific amount, such as the amount of data corruption. The refresh control unit 630 may also maintain the refresh threshold corresponding to the predetermined area as a table 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.

[0135] like Figure 8As shown, when the write processing parameters on a predetermined track are modified to suppress changes in evaluation metrics, edge writes to adjacent tracks may occur, potentially causing data degradation in a predetermined region of the track due to ATI (Automatic Data Interference) and suppressing data degradation in other regions of the track. Therefore, when the write processing parameters on a predetermined track are modified to suppress changes in evaluation metrics, it is preferable to set refresh thresholds for each region of the track by decreasing the refresh threshold for regions where data is easily degraded by ATI and increasing the refresh threshold for regions where data is less susceptible to ATI. In other words, when the write processing parameters on a predetermined track are modified to suppress changes in evaluation metrics, it is preferable to set refresh thresholds for each region of the track by decreasing the refresh threshold for regions where data is easily affected by ATI and increasing the refresh threshold for regions where data is less susceptible to ATI.

[0136] The refresh control unit 630 has refresh thresholds (hereinafter also referred to as partition region thresholds) for each partitioned region on a predetermined track. Based on changes in write processing parameters on the predetermined track, the refresh control unit 630 calculates the partition region thresholds by correcting a certain refresh threshold (hereinafter also referred to as a reference threshold) used for each partitioned region on the predetermined track. In other words, the refresh control unit 630 calculates the changes in partition region thresholds on the predetermined track, which are used to correct the reference thresholds on the predetermined track, and include multiple partition region thresholds corresponding to multiple partitioned regions.

[0137] For example, the refresh control unit 630 calculates each correction value (hereinafter also referred to as a threshold correction value) for each segmented region on the predetermined track based on the change in the TBG value, which corresponds to the change in the correction recording frequency proportional to the change in the correction recording density. In other words, the refresh control unit 630 calculates the change in the threshold correction value on the track that corrects for the change in the refresh threshold on the track based on the change in the TBG value on the predetermined track. The refresh control unit 630 calculates each segmented region threshold based on the reference threshold of each segmented region and the threshold correction value of each segmented region. In other words, the refresh control unit 630 calculates the change in the segmented region threshold on the track based on the change in the reference threshold and the threshold correction value on the predetermined track. For example, the refresh control unit 630 accumulates the threshold correction values ​​of each segmented region to the reference threshold of each segmented region on the predetermined track to calculate the segmented region threshold of each segmented region. In other words, the refresh control unit 630 accumulates the changes in the threshold correction value to the reference threshold on the predetermined track, and calculates the changes in the segmented region threshold on that track. Multiple segmented region thresholds on the predetermined track can also be different. A portion of the multiple segmented region thresholds on the predetermined track can also be the same.

[0138] When the refresh control unit 630 determines that the number of writes corresponding to the target region is greater than the refresh threshold corresponding to the target region, it performs refresh processing on the target region. Furthermore, when the refresh control unit 630 determines that the number of writes corresponding to the target region is greater than the refresh threshold corresponding to the target region, it performs refresh processing on the track including the target region (target track). After performing refresh processing on the target region, the refresh control unit 630 resets the number of writes corresponding to the target region, for example, to 0.

[0139] For example, if it is determined that the number of writes corresponding to an object partition region (e.g., the sum of outward and inward writes) is greater than the partition region threshold corresponding to that object partition region, the refresh control unit 630 reads the object partition region and performs a refresh process that rewrites the data in the object partition region to the same position in the object partition region. Furthermore, if it is determined that the number of writes corresponding to an object partition region is greater than the partition region threshold corresponding to that object partition region, the refresh control unit 630 may also read from the track containing the object partition region (object track) and perform a refresh process that rewrites the data in the track containing the object partition region to the same position in that track.

[0140] Figure 8 This is a schematic diagram illustrating an example of the variation of the TBG value of the predetermined track with respect to the circumferential position and the variation of the threshold correction value with respect to the circumferential position in this embodiment. Figure 8In the diagram, the vertical axis represents the TBG value and threshold correction value, and the horizontal axis represents the circumferential position. Figure 6 In the equation, the TBG value increases as it moves towards the front of the arrow pointing more positively than the origin (=0), and decreases as it moves towards the front of the arrow pointing more negatively than the origin (=0). Figure 8 In the middle, the threshold correction value increases as it moves toward the front end of an arrow that is larger than the origin (=1), and decreases as it moves toward the front end of an arrow that is smaller than the origin (=1). Figure 8 The circumferential position of the horizontal axis includes the start and end positions. Figure 8 The area at the circumference of the horizontal axis, from the start position to the end position, is divided into each subdivided region. Figure 9 The diagram shows the variation of the TBG value (hereinafter also referred to as the variation of the TBG value) on the predetermined track for the circumferential position, TBGL8, and the variation of the threshold correction value (hereinafter also referred to as the variation of the threshold correction value) on the predetermined track for the circumferential position, TCVL8.

[0141] exist Figure 9 In the example shown, the refresh control unit 630 calculates the change in threshold correction value TCVL8 for each division region of the predetermined track based on the change in TBGL8 of the TBG of the predetermined track. The refresh control unit 630 calculates the change in threshold correction value TCVL8 as follows: in division regions where the change in TBGL8 of TBG is smaller than the origin (=0), the change in threshold correction value TCVL8 is larger than the origin (=1); and in division regions where the change in TBGL8 of TBG is larger than the origin (=0), the change in threshold correction value TCVL8 is smaller than the origin (=1). For example, the refresh control unit 630 calculates the change in threshold correction value TCVL8 in a shape that is the inverse of the shape of the change in TBGL8 of TBG, such as a waveform shape. In other words, the refresh control unit 630 calculates the change in threshold correction value TCVL8 in a shape that is the inverse of the shape (waveform shape) of the write processing parameter, such as the change in recording density, corresponding to the change in TBGL8 of TBG. For example, the refresh control unit 630 calculates the change in threshold correction value TCVL8 in a way that is the shape of the change in correction write processing parameters corresponding to the change in TBG, such as the change in correction record density.

[0142] Figure 9 This is a schematic diagram illustrating an example of the variation of the segmentation threshold for a predetermined track in this embodiment. Figure 9 In the diagram, the vertical axis represents the refresh threshold, and the horizontal axis represents the circumferential position. Figure 9 In the middle, the refresh threshold increases as you move towards the front of the larger arrow and decreases as you move towards the front of the smaller arrow. Figure 9 The circumferential position of the horizontal axis includes the start and end positions. Figure 9The area at the circumference of the horizontal axis, from the start position to the end position, is divided into each subdivided region. Figure 8 The diagram shows the reference threshold CTVL9 on the predetermined track and the variation of the partition threshold for the partitioned region on the predetermined track (hereinafter, it is also referred to as the variation of the partition threshold) DATL9.

[0143] exist Figure 10 In the example shown, the refresh control unit 630 will Figure 10 The variation of the threshold correction value, TCVL8, is accumulated to the baseline threshold, CTVL9, to calculate the threshold for each segmented region, thus obtaining the variation of the segmented region threshold, DATL9. The variation of the segmented region threshold, DATL9, corresponds to the variation of the threshold correction value, TCVL8. In other words, the shape (e.g., waveform shape) of the variation of the segmented region threshold, DATL9, is almost identical to the shape of the variation of the threshold correction value, TCVL8. The shape of the variation of the segmented region threshold, DATL9, is almost the reverse of the shape of the variation of write processing parameters, such as the recording density, corresponding to the variation of the TBG, TBGL8. In segmented regions where the variation of TBG, TBGL8, is smaller than the origin (=0), the variation of the segmented region threshold, DATL9, is larger than the baseline threshold, CTVL9; conversely, in segmented regions where the variation of TBG, TBGL8, is larger than the origin (=0), the variation of the segmented region threshold, DATL9, is smaller than the baseline threshold, CTVL9. For example, the variation of the segmented region threshold, DATL9, is more susceptible to a smaller ATI segmented region when writing data to an adjacent track of a predetermined track, and less susceptible to a larger ATI segmented region when writing data to an adjacent track.

[0144] Figure 4 This is a schematic diagram illustrating an example of the division of a predetermined magnetic track. Figure 10 The diagram shows tracks CTRn-1, CTRn, and CTRn+1. Tracks CTRn-1, CTRn, and CTRn+1 correspond to... Figure 10 The magnetic tracks CTRn-1, CTRn, and CTRn+1 are shown. Figure 10 In the example shown, track CTRn-1 is divided into regions DA0(n-1), DA1(n-1), DA2(n-1), DA3(n-1), and DA4(n-1). These regions DA0(n-1), DA1(n-1), DA2(n-1), DA3(n-1), and DA4(n-1) are arranged consecutively in the described order. Figure 10 In the diagram, track CTRn is divided into regions DA0n, DA1n, DA2n, DA3n, and DA4n. These regions DA0n, DA1n, DA2n, DA3n, and DA4n are arranged consecutively in the order they are described. Figure 10In the diagram, track CTRn+1 is divided into regions DA0(n+1), DA1(n+1), DA2(n+1), DA3(n+1), and DA4(n+1). These regions are arranged consecutively in the reverse order as described. Figure 10 In the example shown, in the radial direction, the regions DA0(n-1), DA0n, and DA0(n+1) are arranged consecutively in the inward direction, spaced apart by intervals, in the order described. Figure 10 In the example shown, in the radial direction, the regions DA1(n-1), DA1n, and DA1(n+1) are arranged consecutively in the inward direction, spaced apart by intervals, in the order described. Figure 10 In the example shown, in the radial direction, the regions DA2(n-1), DA2n, and DA2(n+1) are arranged consecutively in the inward direction, spaced apart by intervals, in the order described. Figure 10 In the example shown, in the radial direction, the regions DA3(n-1), DA3n, and DA3(n+1) are arranged consecutively in the inward direction at intervals, in the order described. Figure 10 In the example shown, in the radial direction, the regions DA4(n-1), DA4n, and DA4(n+1) are arranged consecutively in the inward direction with intervals in the order described.

[0145] exist Figure 10 In the example shown, the refresh control unit 630 counts the number of writes to the partitioned regions DA0(n-1) and DA0(n+1). For example, when the refresh control unit 630 writes to the partitioned regions DA0(n-1) and DA0(n+1), it increments the number of writes to the partitioned region DA0n by 1.

[0146] exist Figure 10 In the example shown, the refresh control unit 630 counts the number of writes to the partitioned regions DA1(n-1) and DA1(n+1). For example, when the refresh control unit 630 writes to the partitioned regions DA1(n-1) and DA1(n+1), it increments the number of writes to the partitioned region DA1n by 1.

[0147] exist Figure 10 In the example shown, the refresh control unit 630 counts the number of writes to partitioned regions DA2(n-1) and DA2(n+1). For example, when partitioned regions DA2(n-1) and DA2(n+1) are written to, the refresh control unit 630 increments the number of writes to partitioned region DA2n by 1.

[0148] exist Figure 11 In the example shown, the refresh control unit 630 counts the number of writes to partitioned regions DA3(n-1) and DA3(n+1). For example, when partitioned regions DA3(n-1) and DA3(n+1) are written to, the refresh control unit 630 increments the number of writes to partitioned region DA3n by 1.

[0149] exist Figure 11 In the example shown, the refresh control unit 630 counts the number of writes to partitioned regions DA4(n-1) and DA4(n+1). For example, when partitioned regions DA4(n-1) and DA4(n+1) are written to, the refresh control unit 630 increments the number of writes to partitioned region DA4n by 1.

[0150] Figure 10 This is a schematic diagram illustrating an example of Table TB, which shows the number of writes and the threshold for dividing the region in this embodiment. Figure 11 In the table TB, track CTRn is included. Track CTRn corresponds to... Figure 11 . Figure 12 In this table, TB includes: partitioned regions DA0n, DA1n, DA2n, DA3n, and DA4n; write counts WC0n, WC1n, WC2n, WC3n, and WC4n; and partitioned region thresholds RHT0n, RHT1n, RHT2n, RHT3n, and RHT4n. Table TB can be recorded in predetermined recording areas, such as the system area 10b of disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. Partitioned regions DA0n, DA1n, DA2n, DA3n, and DA4n correspond to tracks CTRn. Write counts WC0n correspond to partitioned region DA0n. Write counts WC1n correspond to partitioned region DA1n. Write counts WC2n correspond to partitioned region DA2n. Write counts WC3n correspond to partitioned region DA3n. Write counts WC4n correspond to partitioned region DA4n. Partitioned region threshold RHT0n corresponds to partitioned region DA0n. The region segmentation threshold RHT1n corresponds to the region segmentation DA1n. The region segmentation threshold RHT2n corresponds to the region segmentation DA2n. The region segmentation threshold RHT3n corresponds to the region segmentation DA3n. The region segmentation threshold RHT4n corresponds to the region segmentation DA4n.

[0151] exist Figure 13In the example shown, when the refresh control unit 630 writes to partitioned regions DA0(n-1) and DA0(n+1), it increases the write count WC0n corresponding to partitioned region DA0n by 1. If the refresh control unit 630 determines that the write count WC0n corresponding to partitioned region DA0n is greater than the partitioned region threshold RHT0n corresponding to partitioned region DA0n, it performs refresh processing on partitioned region DA0n. Furthermore, if the refresh control unit 630 determines that the write count WC0n corresponding to partitioned region DA0n is greater than the partitioned region threshold RHT0n corresponding to partitioned region DA0n, it performs refresh processing on track CTRn.

[0152] When the refresh control unit 630 writes to partitioned regions DA1(n-1) and DA1(n+1), it increments the write count WC1n corresponding to partitioned region DA1n by 1. If the refresh control unit 630 determines that the write count WC1n corresponding to partitioned region DA1n is greater than the partitioned region threshold RHT1n corresponding to partitioned region DA1n, it performs refresh processing on partitioned region DA1n. Furthermore, if the refresh control unit 630 determines that the write count WC1n corresponding to partitioned region DA1n is greater than the partitioned region threshold RHT1n corresponding to partitioned region DA1n, it performs refresh processing on track CTRn.

[0153] When the refresh control unit 630 writes to partitioned regions DA2(n-1) and DA2(n+1), it increments the write count WC2n corresponding to partitioned region DA2n by 1. If the refresh control unit 630 determines that the write count WC2n corresponding to partitioned region DA2n is greater than the partitioned region threshold RHT2n corresponding to partitioned region DA2n, it performs refresh processing on partitioned region DA2n. Furthermore, if the refresh control unit 630 determines that the write count WC2n corresponding to partitioned region DA2n is greater than the partitioned region threshold RHT2n corresponding to partitioned region DA2n, it performs refresh processing on track CTRn.

[0154] When the refresh control unit 630 writes to partitioned regions DA3(n-1) and DA3(n+1), it increments the write count WC3n corresponding to partitioned region DA3n by 1. If the refresh control unit 630 determines that the write count WC3n corresponding to partitioned region DA3n is greater than the partitioned region threshold RHT3n corresponding to partitioned region DA3n, it performs refresh processing on partitioned region DA3n. Furthermore, if the refresh control unit 630 determines that the write count WC3n corresponding to partitioned region DA3n is greater than the partitioned region threshold RHT3n corresponding to partitioned region DA3n, it performs refresh processing on track CTRn.

[0155] When the refresh control unit 630 writes to partitioned regions DA4(n-1) and DA4(n+1), it increments the write count WC4n corresponding to partitioned region DA4n by 1. If the refresh control unit 630 determines that the write count WC4n corresponding to partitioned region DA4n is greater than the partitioned region threshold RHT4n corresponding to partitioned region DA4n, it performs refresh processing on partitioned region DA4n. Furthermore, if the refresh control unit 630 determines that the write count WC4n corresponding to partitioned region DA4n is greater than the partitioned region threshold RHT4n corresponding to partitioned region DA4n, it performs refresh processing on track CTRn.

[0156] ​ This is a flowchart illustrating an example of the refresh threshold setting method in this embodiment.

[0157] On a predetermined track, the MPU60 sets the write processing parameters as the baseline write processing parameters (B1201) and measures the variation of the measured evaluation index on that track (B1202). Based on the measured variation of the measured evaluation index on the predetermined track, the MPU60 calculates the variation of the write processing parameter correction amount on that track to adjust the variation of the measured evaluation index on that track to uniformity or suppression (B1203). Based on the variation of the baseline write processing parameters and the variation of the write processing parameter correction amount, the MPU60 calculates the variation of the corrected write processing parameters for the predetermined track (B1204). Based on the variation of the corrected write processing parameters for the predetermined track, the MPU60 calculates the variation of the threshold correction value on that track by reducing the refresh threshold of areas of the predetermined track that are susceptible to ATI, etc., and increasing the refresh threshold of areas of the track that are not susceptible to ATI, etc. (B1205). In other words, the MPU60 calculates the threshold correction value for each segment of the track based on the changes in the correction write processing parameters of the predetermined track, thereby reducing the refresh threshold of areas of the predetermined track that are susceptible to ATI and increasing the refresh threshold of areas of the track that are less susceptible to ATI and the like. Based on the changes in the threshold correction values ​​on the predetermined track, the MPU60 sets the threshold change for each segment of the track (B1206) and ends the processing. In other words, the MPU60 sets the threshold for each segment of the track based on the threshold correction values ​​for each segment.

[0158] ​ This is a schematic diagram illustrating an example of the refresh processing method of this embodiment.

[0159] MPU60 writes data to adjacent partition regions of the target track in the radial direction that are adjacent to the target partition region (B1301), and counts the number of writes to the target partition region (B1302). MPU60 determines whether the number of writes to the target partition region is greater than or less than the partition region threshold (B1303). If it is determined that the number of writes to the target partition region is less than the partition region threshold ("No" in B1303), MPU60 ends the processing. If it is determined that the number of writes to the target partition region is greater than the partition region threshold ("Yes" in B1303), MPU60 performs a refresh process on the target partition region (B1304) and ends the processing. Alternatively, if it is determined that the number of writes to the target partition region is greater than the partition region threshold, MPU60 may also perform a refresh process on the target track.

[0160] According to this embodiment, the disk drive 1 sets the write processing parameters as reference write processing parameters on a predetermined track and measures the variation of the measured evaluation index on that track. Based on the measured variation of the measured evaluation index on the predetermined track, the disk drive 1 calculates a change in the write processing parameter correction amount on that track to adjust the variation of the measured evaluation index on that track to be uniform or suppressed. Based on the variation of the reference write processing parameters and the change in the write processing parameter correction amount, the disk drive 1 calculates a change in the corrected write processing parameters for the predetermined track. Based on the change in the corrected write processing parameters of the predetermined track, the disk drive 1 calculates a change in the threshold correction value on that track by reducing the refresh threshold of areas of the predetermined track that are easily affected by ATI, etc., and increasing the refresh threshold of areas of the track that are not easily affected by ATI, etc. Based on the change in the threshold correction value on the predetermined track, the disk drive 1 sets a change in the segmentation threshold of that track. Therefore, the disk drive 1 can improve performance and data reliability.

[0161] While several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a wide variety of other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are also included in the scope of the invention as described in the claims and their equivalents.

Claims

1. A disk drive, comprising: The disk has a first track; A head, having a heater, for writing data to the disk and reading data from the disk; and The controller divides the first track into multiple partitioned regions, sets multiple refresh thresholds for rewriting processing in each of the multiple partitioned regions on the first track, and performs data rewriting processing on the first track when it is determined that the first write count of the adjacent partitioned region that is adjacent to the first partitioned region in the radial direction of the disk is greater than the first refresh threshold among the multiple refresh thresholds corresponding to the first partitioned region.

2. The disk drive according to claim 1, The controller sets the variation of parameters associated with write processing to the disk within one week of the first track, so as to suppress the variation of evaluation indicators corresponding to write / read processing characteristics within one week of the first track. Based on the variation of the parameters, the controller sets the variation of the plurality of refresh thresholds.

3. The disk drive according to claim 2, The change in the refresh threshold is the inverse of the change in the shape set by the controller and the change in the shape of the parameter.

4. The disk drive according to claim 3, The change in the evaluation metric is the change in bit error rate.

5. The disk drive according to claim 4, The change in the parameter is a change in the recording density.

6. The disk drive according to claim 4, The change in the parameter is a change in the recorded current.

7. The disk drive according to claim 5, The change in the parameter is a change in the set value of the heater.

8. The disk drive according to claim 5, The change in the parameter is a change in the data transmission speed.

9. The disk drive according to claim 5, The change in the parameter is a change in the recording frequency.

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