Magnetic disk device

Abstract

The embodiment relates to a magnetic disk device. A plurality of first positions are set in the radial direction of the magnetic disk. The plurality of first positions include a plurality of second positions and a third position different from the plurality of second positions. A controller of the magnetic disk device executes a first step in which RRO (Repeatable RunOut) correction values are measured for each of a plurality of second positions, and RRO correction values are not measured for a third position. The controller executes, after the first step, a second step in which access to write or read to the plurality of tracks is performed. The second step includes: acquiring a position error signal by the head at the time of access; and calculating an RRO correction value for the third position based on the position error signal.

Description

[0001] This application claims priority to Japanese Patent Application No. 2024-081566 (Filing date: May 20, 2024). This application incorporates the entire contents of the base application by reference thereto. TECHNICAL FIELD

[0002] The present embodiment relates to a disk device. BACKGROUND

[0003] Conventionally, as one component of a positioning error of a head in a disk device, RRO (Repeatable Run Out) is known. The RRO is a positional deviation of a track of a magnetic track defined based on a burst pattern or the like from a track of an actual magnetic track. The RRO varies in synchronization with rotation of a disk (and a spindle motor).

[0004] In a manufacturing process of a disk device, a correction value (hereinafter referred to as an RRO correction value) for correcting a positional deviation caused by the RRO is measured at a plurality of radius positions. The obtained RRO correction value is saved as additional information of servo data in a nonvolatile storage area. When the disk device is used, the RRO correction value is used to correct the position of the head. SUMMARY

[0005] According to one embodiment, a disk device includes a disk, a head, and a controller. A plurality of first positions at which an RRO correction value is measured are set in a radial direction of the disk. The plurality of first positions include a plurality of second positions and a third position different from the plurality of second positions. The disk has a plurality of magnetic tracks. The head includes a write head that performs a write access to the disk and a read head that performs a read access to the disk. The controller performs a first process of measuring the RRO correction value for each of the plurality of second positions and not measuring the RRO correction value for the third position. The "measuring the RRO correction value for each of the plurality of second positions" includes the following processing: moving the head so that the read head is positioned at a fourth position that is one of the second positions for each of the plurality of second positions; obtaining a first position error signal by the read head while the read head is maintained at the fourth position; and calculating the RRO correction value at the fourth position based on the first position error signal. The controller performs, after the first process, a second process of performing a write or read access to the plurality of magnetic tracks. The second process includes: obtaining a second position error signal by the read head at the time of the access; and calculating the RRO correction value for the third position based on the second position error signal.

[0006] According to one embodiment, a disk device in which an RRO correction value can be measured with high efficiency can be provided. BRIEF DESCRIPTION OF DRAWINGS

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

[0008] Figure 2 is a diagram showing an example of the configuration of a magnetic disk of the embodiment.

[0009] Figure 3 is a diagram for explaining an example of the positional relationship between the read head and the write head of the embodiment.

[0010] Figure 4 is a diagram for explaining that the distance between the head positions of the embodiment differs depending on the position of the magnetic head.

[0011] Figure 5 is a diagram for explaining the plurality of measurement positions and the specific measurement position of the embodiment.

[0012] Figure 6 is a diagram showing an example of the information recorded by the read head position table of the embodiment.

[0013] Figure 7 is a flowchart showing an example of the operation in the manufacturing process performed by the magnetic disk device to which the embodiment is applied.

[0014] Figure 8 is a flowchart showing an example of the operation in the RRO learning process of the magnetic disk device to which the embodiment is applied.

[0015] Figure 9 is a flowchart showing an example of the operation in the write-all process of the magnetic disk device to which the embodiment is applied.

[0016] Figure 10 is a flowchart showing an example of the operation in the read-all process of the magnetic disk device to which the embodiment is applied.

[0017] Figure 11 is a diagram for explaining the estimation method of the RRO correction value at the specific measurement position in the write-all process and the read-all process of the magnetic disk device to which the embodiment is applied.

[0018] Figure 12 is a diagram for explaining another example of the arrangement of the plurality of measurement positions to which the embodiment is applied.

[0019] Explanation of Reference Numerals

[0020] 1 magnetic disk device, 2 host, 11 magnetic disk, 12 SPM, 13 ramp, 15 actuator arm, 16 VCM, 22 magnetic head, 22r read head, 22w write head, 24 preamplifier, 25 RWC, 26 processor, 28 FROM, 29 DRAM, 41 servo track. DETAILED DESCRIPTION

[0021] An embodiment of the present application will be described in detail below with reference to the accompanying drawings. Note that the present application is not limited by this embodiment.

[0022] (Embodiment)

[0023] Figure 1 FIG. 1 is a diagram showing an example of the configuration of a disk device 1 according to an embodiment of the present application.

[0024] The disk device 1 is connected to a host 2. The disk device 1 is capable of receiving an access command such as a write command or a read command from the host 2.

[0025] The disk device 1 has a magnetic disk 11 having a magnetic layer formed on a surface. The disk device 1 performs an access to the magnetic disk 11 in accordance with the access command. The access includes a write of data and a read of data.

[0026] The write and the read of data are performed by a magnetic head 22. Specifically, the disk device 1 has, in addition to the magnetic disk 11, a spindle motor (SPM) 12, a ramp 13, an actuator arm 15, a voice coil motor (VCM) 16, a servo controller (SVC) 21, the magnetic head 22, a hard disk controller (HDC) 23, a preamplifier 24, a read-write channel (RWC) 25, a processor 26, a FROM (Flash Read Only Memory) 28, and a DRAM (Dynamic Random Access Memory) 29.

[0027] The magnetic disk 11 is rotated at a predetermined rotational speed by the SPM 12 coaxially installed.

[0028] The SVC 21 is an integrated circuit having a function as a driver that drives the SPM 12 and the VCM 16. The processor 26 controls the rotation of the SPM 12 and the rotation of the VCM 16 via the SVC 21.

[0029] The magnetic head 22 has a write head 22w and a read head 22r. The magnetic head 22 performs the write of data to the magnetic disk 11 by the write head 22w. The magnetic head 22 performs the read of data to the magnetic disk 11 by the read head 22r. The magnetic head 22 is installed at a front end of the actuator arm 15. The magnetic head 22 is moved in a radial direction of the magnetic disk 11 by the VCM 16 driven by the SVC 21. Note that either one or both of the write head 22w and the read head 22r included in the magnetic head 22 can be provided with a plurality of each.

[0030] The magnetic head 22 is moved onto the ramp 13 when the rotation of the magnetic disk 11 is stopped, or the like. The ramp 13 is configured to hold the magnetic head 22 at a position separated from the magnetic disk 11.

[0031] The preamplifier 24 is an integrated circuit that performs writing and reading of data via the magnetic head 22. The preamplifier 24 amplifies and outputs a signal read by the magnetic head 22 from the disk 11 at the time of a read operation, to the RWC 25. In addition, the preamplifier 24 amplifies a signal corresponding to data to be written, supplied from the RWC 25 at the time of a write operation, and supplies it to the magnetic head 22.

[0032] The HDC 23 performs control of transmission and reception of data between the host 2 via the I / F bus, and control of the DRAM 29, and the like.

[0033] The DRAM 29 is used as a buffer of data transmitted and received between the host 2. For example, the DRAM 29 is used to temporarily store data to be written or data read from the disk 11.

[0034] In addition, the DRAM 29 is used as a memory for an operation by the processor 26. The DRAM 29 is used as an area to load a firmware program and an area to temporarily store various management data.

[0035] The RWC 25 modulates data to be written, supplied from the HDC 23, and supplies it to the preamplifier 24. In addition, the RWC 25 performs demodulation including error correction on a signal supplied from the preamplifier 24, read from the disk 11, and then outputs the signal as digital data to the HDC 23.

[0036] The processor 26 is, for example, a CPU (Central Processing Unit). The FROM 28 and the DRAM 29 are connected to the processor 26.

[0037] The FROM 28 stores a firmware program and various setting information, and the like. In addition, the firmware program can also be stored in the disk 11.

[0038] The processor 26 performs overall control of the disk device 1 in accordance with the firmware program stored in the FROM 28 or the disk 11. For example, the processor 26 loads the firmware program from the FROM 28 or the disk 11 to the DRAM 29, and performs control of the SVC 21, the preamplifier 24, the RWC 25, the HDC 23, and the like in accordance with the firmware program loaded to the DRAM 29.

[0039] In addition, a part or all of the functions of the processor 26 can also be realized by a hardware circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0040] The HDC 23, the RWC 25, and the processor 26 are configured as an SoC (System-On-a-Chip) 30 that is an integrated circuit. The SoC 30 can include other elements (e.g., the FROM 28 or the DRAM 29) in addition to the above-described elements. Further, the SoC 30 is an example of a controller.

[0041] Figure 2 This is a diagram showing an example of the configuration of the magnetic disk 11 of the embodiment. Further, an example of the rotation direction of the magnetic disk 11 is shown in this diagram. The head 22 generates relative movement with respect to the magnetic disk 11 due to the rotation of the magnetic disk 11. Therefore, the write / read direction, that is, the direction in which data is written or read by the head 22 along the circumferential direction is the reverse direction of the rotation direction of the magnetic disk 11.

[0042] In the radial direction, the direction from the edge of the magnetic disk 11 toward the center is the inner diameter (ID) direction, and the direction from the center of the magnetic disk 11 toward the edge is the outer diameter (OD) direction.

[0043] In the manufacturing process, the magnetic disk 11 is written with servo data for positioning of the head 22, for example, by a servo writer or a self-servo write (SSW). According to the servo data written, as an example of the configuration of a servo area, a plurality of servo areas SV are formed that are arranged in a radial pattern in the radial direction and are arranged at predetermined intervals in the circumferential direction. Between two servo areas SV that are continuous in the circumferential direction, a data area DA in which data is written is arranged. Figure 2

[0044] In the radial direction of the magnetic disk 11, a plurality of servo tracks 41 of concentric circles are provided. The servo data written to the servo areas SV is used for positioning of the head 22.

[0045] ​More specifically, a plurality of data tracks of concentric circles are provided on a region of the disk 11 where a plurality of servo tracks 41 are provided. Either the plurality of servo tracks 41 can be used as the plurality of data tracks, or a plurality of data tracks different from the plurality of servo tracks 41 can be provided. On a region of each data track divided by a data area DA, a plurality of data sectors are arranged in a circumferential direction. Data can be written to each data sector by the head 22. Further, the data that can be written to each data sector includes user data received from the host 2, metadata (e.g., error correction code) accompanying the user data, system data, and the like. The disk device 1 holds in advance a setting of the positional relationship of the plurality of servo tracks 41 and the plurality of data tracks. The disk device 1 performs positioning control to position the head 22 at a target data track based on servo data recorded in the servo area SV. The positioning control includes a seek operation that moves the head 22 in a radial direction toward the target data track, a tracking operation that maintains the head 22 on the target data track, and the like.

[0046] Further, the plurality of data tracks is an example of the plurality of tracks.

[0047] The servo data includes sector / cylinder information, a burst pattern, and an RRO correction value, and the like. The sector / cylinder information indicates a servo address (servo sector address) in the circumferential direction of the disk 11 and a position (track number) of a track set in the radial direction. The track number obtained from the sector / cylinder information is an integer value, and the burst pattern indicates an offset amount below the decimal point with the track number as a reference.

[0048] The ideal shape of a track is a true circle. However, due to vibrations and the like received at the time of writing of the servo data, distortion occurs on the servo track 41. Due to this, the position in the radial direction (radial position) determined based on the burst pattern (more accurately, a combination of the sector / cylinder information and the burst pattern) sometimes deviates from the ideal radial position. This positional deviation is one factor that deteriorates positioning accuracy. This positional deviation occurs identically repeatedly with one rotation of the disk (and the spindle motor) as a cycle, and is therefore referred to as RRO. In the manufacturing process, the RRO correction value is learned for a plurality of radial positions. Also, at the time of use of the disk device 1, when the head 22 is positioned at a target track, control is performed to eliminate the positional deviation due to RRO based on the RRO correction value.

[0049] Further, the storage location of each RRO correction value obtained for the plurality of radial positions can not necessarily be the servo area SV, but can be a nonvolatile storage region. Each RRO correction value can be stored in the data area DA, or in a nonvolatile memory such as the FROM 28. In the disk device 1, the RRO correction value is read from the nonvolatile storage region, and the RRO correction value obtained by the reading is used to perform correction of the position of the head 22.

[0050] Hereinafter, the process of measuring the RRO correction value at a plurality of radius positions is referred to as an RRO learning process. Further, each radius position at which the RRO correction value is measured is referred to as a measurement position or an RRO measurement position. The correction of the position deviation caused by the RRO is referred to as RRO correction.

[0051] The plurality of measurement positions can be set regardless of the configuration of the data track group. In a case where the target data track exists at a radius position between two measurement positions adjacent to each other, the SoC 30 performs the RRO correction as follows. That is, the SoC 30 estimates the RRO correction value at the radius position of the target data track by interpolation of a plurality of RRO correction values including the RRO correction value of each of the two measurement positions. Further, the SoC 30 performs the RRO correction using the RRO correction value obtained by the estimation.

[0052] The interpolation can be linear interpolation using the RRO correction value of each of the two measurement positions adjacent to the target data track. Alternatively, the interpolation can be polynomial interpolation of order two or more using the RRO correction value of each of three or more measurement positions including the two measurement positions.

[0053] In order to improve the positioning accuracy as much as possible, the plurality of measurement positions is set at as fine intervals as possible in the radial direction. Further, the measurement of the RRO correction value at one measurement position includes the measurement of the position error signal at the one measurement position and the calculation of the RRO correction value based on the measured position error signal. Since a large number of measurement positions is set and the RRO correction value is measured for all of the measurement positions, the RRO learning process requires a large amount of time.

[0054] In the embodiment, in order to shorten the time required to measure the RRO correction value of all of the measurement positions, the SoC 30 is configured to skip the measurement of the RRO correction value at several measurement positions in the RRO learning process.

[0055] In the manufacturing process, a process of writing data to all of the data tracks of the disk 11, a process of reading data from all of the data tracks of the disk 11, and the like are included after the RRO learning process. The operation of writing data to all of the data tracks of the disk 11 is referred to as a write-all process. The operation of reading data from all of the data tracks of the disk 11 is referred to as a read-all process. The pair of the write-all process and the read-all process is performed for the detection of defective data sectors and the verification of whether each data sector can be normally accessed. The pair of the write-all process and the read-all process can be performed a plurality of times. In the manufacturing process, a process of detecting defective data sectors, a process of detecting defective servo sectors, and the like can be included in addition to the write-all process and the read-all process.

[0056] The plurality of measurement positions can include the radial position accessed in the write-all process or the read-all process. Such a radial position of the plurality of measurement positions accessed in the write-all process or the read-all process is referred to as a specific measurement position. In a case where the plurality of measurement positions include the radial position accessed in the detection process of the defect data sector, the detection process of the defect servo sector, the radial position can also be set as the specific measurement position.

[0057] The SoC 30 skips the measurement of the RRO correction value at the specific measurement position in the RRO learning process. Also, the SoC 30 performs the measurement of the RRO correction value at the specific measurement position when the specific measurement position or the vicinity of the specific measurement position is accessed in the write-all process or the read-all process after the RRO learning process. Thus, in the RRO learning process, the seek operation of the head 22 and the tracking operation of the amount of one revolution of the data track are omitted for each specific measurement position, and the time required for measuring the RRO correction values of all the measurement positions is shortened. That is, the measurement efficiency of the RRO correction value is improved.

[0058] Before details of the plurality of measurement positions and the specific measurement position are described, the radial position passed through by the read head 22r and the radial position passed through by the write head 22w are described.

[0059] Figure 3 is a drawing for explaining an example of the positional relationship between the read head 22r and the write head 22w in the embodiment. According to the example shown in this drawing, the read head 22r and the write head 22w are arranged in the direction in which the actuator arm 15 extends. Also, the read head 22r is disposed closer to the rotation axis side of the actuator arm 15 than the write head 22w.

[0060] In Figure 3 the example shown in the drawing, in a case where the read head 22r is positioned to a certain data track, the angle θ formed by the arrangement direction of the read head 22r and the write head 22w and the tangent direction of the positioned track is not zero. Thus, the radial position of the read head 22r and the radial position of the write head 22w are different. When the distance from the rotation center C of the disk 11 to the radial position of the read head 22r is denoted as r r , and the distance from the rotation center C of the disk 11 to the radial position of the write head 22w is denoted as r w , the radial position of the read head 22r and the radial position of the write head 22w are separated by L (= |r r -r w |) in the radial direction of the disk 11. Hereinafter, L is referred to as the distance between head positions.

[0061] The distance between head positions can be different depending on the position of the head 22. Figure 4This is a diagram used to illustrate that "the distance between the head positions in the embodiment varies depending on the position of the magnetic head 22".

[0062] For example, at position P a1 The write head 22w and the read head 22r are configured to be orthogonal to the radial direction. In this case, the radial position of the read head 22r is equal to the radial position of the write head 22w, therefore, the distance L between the head positions is zero.

[0063] When the magnetic head 22 is at position P a1 Region A on the inner periphery inner In cases such as when the magnetic head 22 is at position P a2 In the case of, with Figure 3 Similarly, in the example shown, the write head 22w is located on the inner periphery side compared to the read head 22r. That is, the distance L between the head positions is not zero. Furthermore, the value of the distance L between the head positions changes with the position of the read / write head 22 from position P. a1 It grows larger as it moves away from the inner periphery.

[0064] When the magnetic head 22 is at position P a1 Region A on the outer periphery outer In cases such as when the magnetic head 22 is at position P a3 In this case, the write head 22w is located on the outer periphery of the disk 11 closer than the read head 22r. That is, the distance L between the head positions is not zero. Furthermore, the value of the distance L between the head positions changes from position P as the read / write head 22 moves. a1 It grows larger as it moves away from the outer periphery.

[0065] also, Figure 3 and Figure 4 The example shown is just one example. For instance, the configuration orientation of the write head 22w and the read head 22r may not be consistent with the direction in which the actuator arm 15 extends.

[0066] Figure 5 This is a diagram used to illustrate multiple measurement locations and a specific measurement location of the embodiment. In this diagram, region A in the recording surface of disk 11 is shown. outer It includes a portion of the area. That is, the write head 22w is located on the outer periphery of the disk 11, which is closer to the read head 22r.

[0067] Multiple measurement locations were assigned identification numbers, each progressively larger than the previous one, facing inwards. The measurement location with the identification number X (where X is a numerical value) was denoted as measurement location #X. Figure 5 The image shows 15 measurement locations #0 to #14 as examples of multiple measurement locations.

[0068] In addition, each data track is assigned an identification number that increases with each subsequent "1" towards the inner periphery (hereinafter referred to as the data track number). The data track with the data track number Y (where Y is numerical information) is denoted as data track DTrk#Y. Figure 5 The image shows three data tracks DTrk#0 to DTrk#2 as an example of multiple data tracks DTrk.

[0069] As mentioned earlier, multiple measurement positions are set independently of the configuration of each data track DTrk. Here, as an example, the three data tracks DTrk#0 to DTrk#2 are set at intervals equal to the track pitch DTp. Furthermore, 15 measurement positions #0 to #14 are set at intervals equal to 1 / 4 of the track pitch SvTP of the servo track 41 (i.e., 0.25 × SvTP intervals). 0.25 × SvTP is different from DTp.

[0070] exist Figure 5 In the example shown, the radius position of data track DTrk#0 coincides with measurement position #1. The radius position of data track DTrk#1 is located between measurement positions #5 and #6. The radius position of data track DTrk#2 coincides with measurement position #10.

[0071] Hereafter, the radius position of the read head 22r will be denoted as the read head position.

[0072] During the reading operation of data track DTrk#0, a tracking operation is performed such that the read head 22r moves along DTrk#0. That is, the tracking operation is performed such that the read head 22r is maintained at the read head position Pr0. Furthermore, data track DTrk#0 (and read head position Pr0) coincides with measurement position #1. In other words, when the reading operation of data track DTrk#0 is performed during the entire reading process, the RRO correction value at measurement position #1 can be measured. Therefore, measurement position #1 is set as a specific measurement position for measuring the RRO correction value during the entire reading process.

[0073] During the write operation on data track DTrk#0, a tracking operation is performed such that the write head 22w moves along DTrk#0. At this time, the read head 22r is maintained at a radius position (L) away from the head position distance in the direction of ID from DTrk#0. Figure 5 The read head position Pw0). For example, when the write head 22w is located at position Pwh on data track DTrk#0, the read head 22r is located at position Prh, which is a distance L between the head positions, moving from position Pwh on data track DTrk#0 in the ID direction. Furthermore, in Figure 5In the example shown, the radial position (read head position PwO) from the data track DTrk#0 by the head position interval distance L in the ID direction coincides with the measurement position #4. That is, when the write operation on the data track DTrk#0 is performed in the write all process, the measurement of the RRO correction value at the measurement position #4 can be performed. Thus, the measurement position #4 is set as the specific measurement position at which the measurement of the RRO correction value is performed in the write all process.

[0074] In the read operation on the data track DTrk#l, the tracking operation is performed in such a manner that the read head 22r moves along the DTrk#l (read head position Prl). The read head position Prl does not coincide with any measurement position. Figure 5

[0075] In the write operation on the data track DTrk#l, the tracking operation is performed in such a manner that the write head 22w moves along the DTrk#l. At this time, the read head 22r moves at a radial position (read head position Pwl) from the DTrk#l by the head position interval distance L in the ID direction. The read head position Pwl does not coincide with any measurement position. Figure 5

[0076] In the read operation on the data track DTrk#2, the tracking operation is performed in such a manner that the read head 22r moves along the DTrk#2. That is, the tracking operation is performed in such a manner that the read head 22r is maintained at the read head position Pr2. Also, the data track DTrk#2 (and the read head position Pr2) coincides with the measurement position #10. That is, when the read operation on the data track DTrk#2 is performed in the read all process, the measurement of the RRO correction value at the measurement position #10 can be performed. Thus, the measurement position #10 is set as the specific measurement position at which the measurement of the RRO correction value is performed in the read all process.

[0077] In the write operation on the data track DTrk#2, the tracking operation is performed in such a manner that the write head 22w moves along the DTrk#2. At this time, the read head 22r moves at a radial position (read head position Pw2) from the DTrk#2 by the head position interval distance L in the ID direction. The read head position Pw2 does not coincide with any measurement position. Figure 5 Figure 5 In the example shown, the read head position Pw2 coincides with the measurement position #13. That is, when the write operation on the data track DTrk#2 is performed in the write all process, the measurement of the RRO correction value at the measurement position #13 can be performed. Thus, the measurement position #13 is set as the specific measurement position at which the measurement of the RRO correction value is performed in the write all process.

[0078] ​​​SoC 30 skips the measurement of the RRO correction values at the measurement positions #1, #4, #10, and #13, which are the specific measurement positions, among the measurement positions #0 to #14 in the RRO learning process. Also, SoC 30 performs the measurement of the RRO correction values at the measurement positions #4 and #13 in the write-all process. SoC 30 performs the measurement of the RRO correction values at the measurement positions #1 and #10 in the read-all process.

[0079] Hereinafter, the group of the head positions at the time of the write operation on each data track DTrk in the write-all process is referred to as the head position group in the write-all process. Also, the group of the head positions at the time of the read operation on each data track DTrk in the read-all process is referred to as the head position group in the read-all process. For example, Figure 6 The head positions Pw0, Pwl, and Pw2 shown in the drawing are included in the head position group in the write-all process. The head positions Pr0, Prl, and Pr2 are included in the head position group in the read-all process.

[0080] Further, the plurality of measurement positions (for example, the measurement positions #0 to #14) are an example of the plurality of first positions. The specific measurement position among the plurality of measurement positions is an example of the third position. The measurement positions (for example, the measurement positions #0, #2, #3, #5 to #9, #11, #12, #14) other than the specific measurement position among the plurality of measurement positions are an example of the second measurement position.

[0081] The head position group in the write-all process and the head position group in the read-all process are recorded in the head position table, which is one of the setting information. The head position table is stored in a predetermined storage area (for example, the FROM 28) in the disk device 1. The head position table can also be generated outside the disk device 1 and stored in the predetermined storage area. Alternatively, SoC 30 can generate the head position table by an arbitrary method and store it in the predetermined storage area.

[0082] Figure 5 is a drawing showing an example of information recorded in the head position table of the embodiment. As shown in the drawing, the correspondence relationship between the data track number and the position of the head 22r at the time of the read operation and the position of the head 22r at the time of the write operation is recorded in the head position table. From the drawing, it is read that "in the area on the outer circumference side (corresponding to the area A outer , the position of the head 22r at the time of the write operation is located at the inner circumference side than the position of the head 22r at the time of the read operation, in the area on the inner circumference side (corresponding to the area A inner , the position of the head 22r at the time of the write operation is located at the outer circumference side than the position of the head 22r at the time of the read operation".

[0083] For example, the SoC 30 determines whether a certain measurement position coincides with any of the read head position group in the write all process or the read head position group in the read all process, based on the read head position table in the RRO learning process. In a case where the measurement position coincides with any of the read head positions, the SoC 30 determines that the measurement position is a specific measurement position. In a case where the measurement position does not coincide with any of the read head positions, the SoC 30 determines that the measurement position is not a specific measurement position.

[0084] Further, even if the measurement position does not coincide with any of the read head position group in the write all process or the read head position group in the read all process, the SoC 30 can determine that the measurement position is a specific measurement position in a case where a predetermined condition is satisfied. For example, in a case where a distance from a certain measurement position to the nearest read head position to the measurement position among the read head position group in the write all process or the read head position group in the read all process is less than a threshold value Dth, the SoC 30 determines that the measurement position is a specific measurement position. In a case where a distance from a certain measurement position to the nearest read head position to the measurement position among the read head position group in the write all process or the read head position group in the read all process is greater than the threshold value Dth, the SoC 30 determines that the measurement position is not a specific measurement position. In a case where a distance from a certain measurement position to the nearest read head position to the measurement position among the read head position group in the write all process or the read head position group in the read all process is equal to the threshold value Dth, the SoC 30 can determine that the measurement position is a specific measurement position, and the SoC 30 can also determine that the measurement position is not a specific measurement position. The threshold value Dth is, for example, a value below the interval of the measurement positions.

[0085] For example, consider a case where the threshold value Dth coincides with the interval of the measurement positions. Since Figure 7 Since the distances from the measurement positions #5, #6 to the read head position Pr1 are both below the threshold value Dth, the SoC 30 regards the measurement positions #5, #6 as specific measurement positions. Also, the SoC 30 skips the measurement of the RRO correction value at the measurement positions #5, #6 in the RRO learning process. In the read all process, the SoC 30 first measures the RRO correction value at the read head position Pr1 when performing the read operation on the data track DTrk #1. Then, the SoC 30 estimates the RRO correction value at the measurement position #5 by interpolation using the RRO correction value at the measurement position #4 and the RRO correction value at the read head position Pr1. Also, the SoC 30 estimates the RRO correction value at the measurement position #6 by interpolation using the RRO correction value at the read head position Pr1 and the RRO correction value at the measurement position #7. Further, in this example, the interpolation is, for example, linear interpolation. The SoC 30 can also perform a polynomial interpolation of order 2 or higher.

[0086] In the following description, the SoC 30 is configured to regard a measurement position at which the distance from the read head position group in the write all process or any of the read head positions in the read all process is equal to or less than the threshold value Dth as a specific measurement position.

[0087] Further, the threshold value Dth can also be 0. In the case where the threshold value Dth is 0, the SoC 30 regards only a measurement position in the plurality of measurement positions that coincides with any of the read head positions in the read all process as a specific measurement position.

[0088] Next, the operation of the disk device 1 according to the embodiment will be described.

[0089] Figure 7 is a flowchart showing an example of the operation in the manufacturing process performed by the disk device 1 according to the embodiment. Figure 7 The flowchart of is a flowchart in which a part of the process is extracted, and the process not shown in the flowchart of can also be performed. Figure 8 For example, the adjustment for implementing accurate servo control, the adjustment for recording user data, the adjustment for determining the format of user data, the defect servo sector investigation process, the medium defect investigation process, and the like are not shown in the flowchart of.

[0090] The SoC 30 performs the RRO learning process (S101). The RRO learning process is performed after the disk device 1 is assembled and servo data other than the RRO correction value is written to the servo area SV of the disk 11. For example, the processor 26 controls a series of operations of the RRO learning process in accordance with a dedicated firmware program.

[0091] After the process of S101, the SoC 30 performs the write all process (S102). As described above, in the write all process, the writing of data to all data tracks DTrk is performed. Next, the SoC 30 performs the read all process (S103). In the read all process, the reading of data from all data tracks DTrk is performed.

[0092] Then, the operation in the manufacturing process ends.

[0093] Further, as described above, the pair of the process of S102 and the process of S103 can be performed multiple times after the process of S101. The RRO learning process of S101 is an example of the first process. The write all process of S102 and the read all process of S103 are examples of the second process.

[0094] Figure 9 is a flowchart showing an example of the operation in the RRO learning process of the disk device 1 according to the embodiment.

[0095] First, the SoC 30 initializes a variable X to 0 (S201). X is a variable that can take a value of a range of identification numbers assigned to the measurement positions, and is also an index used in the following loop processing. The maximum value of the identification numbers assigned to the measurement positions is denoted by Xmax max .

[0096] The SoC 30 determines whether the distance from the measurement position #X to the read head position in the read head position group in the read all process and the read head position in the read head position group in the read all process closest to the measurement position #X (denoted by the nearest read head position) is equal to or less than the threshold value Dth (S202). The SoC 30 can determine the nearest read head position, for example, based on the read head position table.

[0097] In a case where the distance from the measurement position #X to the nearest read head position is equal to or less than the threshold value Dth (YES in S202), the SoC 30 stores the measurement position #X as a specific measurement position (S203). At this time, the SoC 30 stores the nearest read head position in association with the measurement position #X. The storage area in which the measurement position #X as the specific measurement position is stored is not limited to a specific storage area. For example, the SoC 30 stores the measurement position #X as the specific measurement position and the nearest read head position in pairs in the DRAM 29.

[0098] In a case where the distance from the measurement position #X to the nearest read head position is not equal to or less than the threshold value Dth (NO in S202), the SoC 30 performs a seek operation that moves the read head 22r to the measurement position #X (S204).

[0099] The SoC 30 acquires a position error signal at the measurement position #X while performing a tracking operation that maintains the read head 22r at the measurement position #X (S205). The position error signal is obtained by demodulation of servo data when the read head 22r passes through the servo area SV. The SoC 30 acquires the position error signal for the amount of one rotation of the disk 11. The position error signal acquired by this processing is an example of the first position error signal.

[0100] The SoC 30 calculates an RRO correction value at the measurement position #X based on the position error signal for the amount of one rotation of the disk 11 at the measurement position #X (S206). The SoC 30 calculates the RRO correction value at each servo area SV for the amount of one rotation of the disk 11.

[0101] The SoC 30 stores the RRO correction value at each servo area SV for the amount of one rotation of the disk 11 at the measurement position #X in a nonvolatile storage area (S207). As described above, the nonvolatile storage area of the storage destination can be the servo area SV of the disk 11, can be the data area DA, or can be the FROM 28.

[0102] After the processing of S203 or the processing of S207, the SoC 30 determines whether X is equal to X max (S208).

[0103] In a case where X is not equal to X max ("No" in S208), the SoC 30 increments the value of X by 1 (S209), and the control moves to S202. In a case where X is equal to X max ("Yes" in S208), the RRO learning procedure is completed.

[0104] Figure 10 is a flowchart showing an example of the operation in the entire write procedure of the magnetic disk device 1 according to the embodiment.

[0105] First, the SoC 30 initializes a variable Y to 0 (S301). Y is a variable that can take a value in the range of data track numbers, and is also an index used in the following loop processing. The maximum value of data track numbers is denoted as Y max .

[0106] The SoC 30 performs a seek operation that moves the write head 22w to the data track DTrk#Y (S302).

[0107] Then, the SoC 30 performs a write operation that writes data to the data track DTrk#Y, and saves the position error signal in the write operation (S303).

[0108] In the processing of S303, the SoC 30 acquires the position error signal by demodulating the servo data while the read head 22r passes the servo area SV. The SoC 30 continues the write operation while performing a tracking operation that maintains the write head 22w on the data track DTrk#Y based on the position error signal. In the write operation, the SoC 30 saves the position error signal of the amount of one rotation of the disk 11 acquired at the read head position. The position where the position error signal is saved is not limited to a particular position. For example, the SoC 30 saves the position error signal in the DRAM 29. The position error signal acquired by this processing is an example of the 2nd position error signal.

[0109] Next, the SoC 30 determines whether the read head position in the write operation to the data track DTrk#Y is associated with a particular measurement position (S304).

[0110] In a case where the read head position in the write operation to the data track DTrk#Y is associated with a particular measurement position ("Yes" in S304), the SoC 30 calculates the RRO correction value at the read head position (S305). The SoC 30 calculates the RRO correction value at each servo area SV of the amount of one rotation of the disk 11.

[0111] Next, the SoC 30 estimates the RRO correction value at the specific measurement position associated with the read head position in the write operation to the data track DTrk#Y by using interpolation of the RRO correction value at the read head position (S306). In the process of S306, the SoC 30 also estimates the RRO correction value at each servo area SV of the amount of one rotation of the disk 11.

[0112] The SoC 30 stores the RRO correction value at each servo area SV of the amount of one rotation of the disk 11 at the specific measurement position in a nonvolatile storage area (S307). As described above, the nonvolatile storage area of the storage destination can be the servo area SV of the disk 11, can be the data area DA, or can be the FROM 28.

[0113] In a case where the read head position in the write operation to the data track DTrk#Y is not associated with the specific measurement position (NO in S304), or after the process of S307, the SoC 30 determines whether Y is equal to Y max (S308).

[0114] In a case where Y is not equal to Y max (YES in S308), the write all procedure is completed. max

[0115] Figure 9 is a flowchart showing an example of the operation in the read all procedure of the disk device 1 according to the embodiment.

[0116] First, the SoC 30 initializes a variable k to 0 (S401). Y is a variable that can take a value in the range of the data track number, and is also an index used in the loop process later.

[0117] The SoC 30 performs a seek operation to move the read head 22r to the data track DTrk#Y (S402).

[0118] Then, the SoC 30 performs a read operation to read data from the data track DTrk#Y, and stores the position error signal in the read operation (S403).

[0119] ​In the processing of S403, the SoC 30 acquires a position error signal by demodulating the servo data when the read head 22r passes the servo area SV. The SoC 30 continues the read operation while performing a tracking operation based on the position error signal to maintain the read head 22r on the data track DTrk#Y. In the read operation, the SoC 30 stores the acquired position error signal for one rotation of the disk 11. The position where the position error signal is stored is not limited to a specific position. For example, the SoC 30 stores the position error signal in the DRAM 29.

[0120] Next, the SoC 30 determines whether the read head position in the read operation on the data track DTrk#Y, i.e., the data track DTrk#Y, is associated with the specific measurement position (S404).

[0121] In a case where the read head position in the read operation on the data track DTrk#Y is associated with the specific measurement position (YES in S404), the SoC 30 calculates the RRO correction value at the read head position (S405). The SoC 30 calculates the RRO correction value at each servo area SV for one rotation of the disk 11.

[0122] Next, the SoC 30 estimates the RRO correction value at the specific measurement position associated with the read head position using interpolation using the RRO correction value obtained by the calculation in the processing of S405 (S406). In the processing of S406, the SoC 30 also estimates the RRO correction value in each servo area SV for one rotation of the disk 11.

[0123] The SoC 30 stores the RRO correction value at each servo area SV for one rotation of the disk 11 at the specific measurement position in a nonvolatile storage area (S407). As described above, the nonvolatile storage area of the storage destination can be the servo area SV of the disk 11, can be the data area DA, or can be the FROM 28.

[0124] In a case where the read head position in the read operation on the data track DTrk#Y is not associated with the specific measurement position (NO in S404), or after the processing of S407, the SoC 30 determines whether Y is equal to Y max (S408).

[0125] In a case where Y is not equal to Y max (S408), the SoC 30 increments the value of Y by 1 (S409), and the control moves to S402. In a case where Y is equal to Y max (S408), the read all procedure is completed.

[0126] Further, in the positioning in the write all procedure (for example, the positioning in the write operation on the data track DTrk#Y in the write all procedure), the SoC 30 can use the RRO correction value at the specific measurement position associated with the read head position in the read operation on the data track DTrk#Y.Figure 10 the processing of S303-S304) and the positioning in the read all process (e.g. the processing of S403-S404), the SoC 30 uses the RRO correction value determined through the RRO learning process at the time of the seek operation and the tracking operation. However, in the RRO learning process, the determination of the RRO correction value at the specific determination position is skipped. Therefore, the SoC 30 can estimate the RRO correction value at the specific determination position by interpolation and use the RRO correction value obtained by the estimation in the positioning in the write all process and the positioning in the read all process. Figure 11

[0127] Figure 11 is a diagram for explaining a method of estimating the RRO correction value at the specific determination position in the write all process and the read all process of the disk device 1 involved in the embodiment.

[0128] In the example shown in FIG. 8, the SoC 30 estimates the RRO correction value at each of the determination positions #1, #4, #10, and #13, which are the specific determination positions, by linear interpolation of the RRO correction values at the two adjacent determination positions in the write all process or the read all process. Figure 9 The SoC 30 estimates the RRO correction values at the determination positions #4 and #13 by the above method and uses the RRO correction values obtained by the estimation in the processing of S303-S304.

[0129] Figure 10 The SoC 30 estimates the RRO correction values at the determination positions #1 and #10 by the above method and uses the RRO correction values obtained by the estimation in the processing of S403-S404. Figure 9 Further, the SoC 30 updates the RRO correction value at the specific determination position in the processing of determining the RRO correction value at the specific determination position (e.g. the processing of S305-S306 or the processing of S405-S406).

[0130] Figure 10 Figure 12

[0131] As such, by estimating the RRO correction value at the specific determination position and using the RRO correction value obtained by the estimation in the positioning in the write all process or the read all process, it is possible to suppress the deterioration of the accuracy of the positioning in the write all process or the read all process due to the skipping of the determination of the RRO correction value at the specific determination position in the RRO learning process.

[0132] In the above example, the plurality of determination positions are arranged at equal intervals. The plurality of determination positions can not necessarily be arranged at equal intervals.

[0133] Figure 12 ​​​​​is a diagram for explaining another example of the configuration of the plurality of measurement positions involved in the embodiment.

[0134] In Figure 12 In the example shown, the measurement positions are configured at positions that are a predetermined distance lpos away from the reference position in the ID direction and positions that are a predetermined distance lpos away from the reference position in the OD direction, with the read head position at the time of the write operation as the reference position.

[0135] In Figure 12 In the example shown, the measurement positions are configured at positions that are a predetermined distance lpos away from the reference position in the ID direction and positions that are a predetermined distance lpos away from the reference position in the OD direction, with the read head position at the time of the write operation as the reference position.

[0136] In the read operation on the data track DTrk#0, a tracking operation is performed in such a manner that the read head 22r moves along DTrk#0 (read head position Pr10). In the read operation on the data track DTrk#1, a tracking operation is performed in such a manner that the read head 22r moves along DTrk#1 (read head position Pr11). In the read operation on the data track DTrk#2, a tracking operation is performed in such a manner that the read head 22r moves along DTrk#2 (read head position Pr12).

[0137] In this manner, the read head positions Pw10, Pw11, Pw12 are included in the read head position group in the write all procedure, and the read head positions Pr10, Pr11, Pr12 are included in the read head group in the read all procedure.

[0138] Here, the measurement position #1 coincides with the read head position Pr11. Also, the measurement position #3 coincides with the read head position Pr12. In this manner, the SoC 30 determines that the measurement positions #1, #3 are specific measurement positions, and in the RRO learning procedure, the measurement of the RRO correction value at the measurement positions #1, #3 is skipped. Also, the SoC 30 measures the RRO correction value at the measurement positions #1, #3 in the read all procedure.

[0139] Also, in the example shown in Figure 7 Also in the example shown, the SoC 30 can determine that a certain measurement position is a specific measurement position when the distance from that measurement position to the nearest read head position in the read head position group in the write all procedure or the read head position group in the read all procedure is equal to or less than the threshold value Dth.

[0140] As described above, according to the embodiment, the plurality of measurement positions are set in the radial direction of the magnetic disk 11. The plurality of measurement positions include the specific measurement position. The SoC 30 executes the RRO learning process (for example, refer to S101 of Figure 7 FIG. 10) and, after the RRO learning process, executes the write all process and the read all process (for example, refer to S102, S103 of Figure 8 FIG. 11). In the RRO learning process, the SoC 30 measures the RRO correction value at each measurement position of the plurality of measurement positions except for the specific measurement position, and does not measure the RRO correction value at the specific measurement position (for example, refer to Figure 8 FIG. 12). The measurement of the RRO correction value at one measurement position includes the following processes: moving the head 22 in such a manner that the read head 22r is positioned at the one measurement position (for example, refer to S204 of Figure 8 FIG. 13); obtaining the position error signal by the read head 22r while maintaining the read head 22r at the one measurement position (for example, refer to S205 of Figure 8 FIG. 14); and calculating the RRO correction value at the one measurement position based on the position error signal (for example, refer to S206 of Figure 9 FIG. 15). In the write all process and the read all process, the SoC 30 includes the following processes: obtaining the position error signal by the read head 22r at the time of accessing the plurality of data tracks (for example, refer to S303 of Figure 10 FIG. 16, S403 of Figure 9 FIG. 17); and calculating the RRO correction value at the specific measurement position based on the position error signal (for example, refer to S305, S306 of Figure 10 FIG. 18, S405, S406 of Figure 9 FIG. 19).

[0141] That is, in the RRO learning process, for the specific measurement position, the seek operation of the head 22 and the tracking operation of the amount of one revolution of the data track are omitted. Also, in the post-process of the RRO learning process (the write all process or the read all process), the measurement of the RRO correction value at the specific measurement position is performed incidentally at the time of performing the write operation or the read operation. Thereby, the time required for the measurement of the RRO correction value at all measurement positions is shortened. That is, the measurement efficiency of the RRO correction value is improved.

[0142] In addition, according to the embodiment, the SoC 30 determines that the measurement position is the specific measurement position in a case where the distance between the measurement position and the read head position closest to the measurement position among the read head position group in the write all process or the read head position group in the read all process is less than the threshold value Dth. The SoC 30 determines that the measurement position is not the specific measurement position in a case where the distance between the measurement position and the read head position closest to the measurement position among the read head position group in the write all process or the read head position group in the read all process is greater than the threshold value Dth.

[0143] And, according to the embodiment, the SoC 30 calculates the RRO correction value at the specific measurement position based on the position error signal acquired from the read head position nearest to the specific measurement position among the read head position group in the write all process or the read head position group in the read all process at the time of access to one of the plurality of data tracks in the write all process or the read all process (for example, refer to Figure 10 S303 to S306 of FIG. 3, ​ S403 to S406 of FIG. 4).

[0144] Thus, the time required for measurement of the RRO correction value at all the measurement positions is shortened. That is, the efficiency of measurement of the RRO correction value is improved.

[0145] Further, according to the embodiment, the SoC 30 performs the determination of the specific measurement position based on the read head position table that is the information in which the read head position group in the write all process and the read head position group in the read all process are recorded.

[0146] Further, the method of determination of the specific measurement position is not limited to the method using the read head position table. In the case where the intervals of the plurality of measurement positions are uniform, the SoC 30 can divide the numerical information indicating each read head position of the read head position group in the write all process and the read head position group in the read all process by the interval of the measurement positions, and perform the determination of the specific measurement position based on the value obtained by the division.

[0147] In addition, according to the embodiment, the SoC 30 estimates the RRO correction value at the specific measurement position using the RRO correction values at at least two of the measurement positions other than the specific measurement position. And, in the write operation or the read operation to the plurality of data tracks in the write all process or the read all process, the SoC 30 performs the positioning of the head 22 using the RRO correction value obtained by the estimation.

[0148] Thus, it is possible to suppress the deterioration of the accuracy of positioning in the write all process or the read all process due to the skipping of the measurement of the RRO correction value at the specific measurement position in the RRO learning process.

[0149] Several embodiments of the present application have been described above with reference to the accompanying drawings, which are presented by way of example and not limitation. These new embodiments can be carried out in various other ways without departing from the spirit or essential characteristics of the application. The embodiments and their variations encompassed within the scope of the application are not limited to the examples described herein, but can vary freely within the scope of the application, without departing from the spirit of the application. These embodiments and their variations are included within the scope of the application, the essential characteristics of the application, and the scope of the application recited in the claims.

Claims

1. A disk device, provided with a disk, a head, and a controller, the disk is provided with a plurality of first positions where a RRO correction value is measured in a radial direction, the plurality of first positions include a plurality of second positions and a third position different from the plurality of second positions, the disk is provided with a plurality of tracks, the head is provided with a write head that performs a write access to the disk and a read head that performs a read access to the disk, the controller performs a first process and a second process after the first process, in the first process, a RRO correction value at each of the plurality of second positions is measured, and a RRO correction value at the third position is not measured, The determination of the RRO correction value at each of the plurality of second positions includes: for each of the plurality of second positions, the head is moved so that the read head is positioned at a fourth position that is one of the second positions, a first position error signal is acquired by the read head while the read head is maintained at the fourth position, and a RRO correction value at the fourth position is calculated based on the first position error signal, in the second process, the write access or the read access to the plurality of tracks is performed, the second process includes acquiring a second position error signal by the read head at the time of the access, and a RRO correction value at the third position is calculated based on the second position error signal.

2. The disk device according to claim 1, the controller, determines a first position among the plurality of first positions that is farther than a threshold value from a closest fifth position among a plurality of fifth positions as one of the plurality of second positions, each of the fifth positions is a position of the read head at the time of an access to one of the plurality of tracks, determines a first position among the plurality of first positions that is closer than the threshold value to the closest fifth position among the plurality of fifth positions as the third position.

3. The disk device according to claim 2, the second position error signal is a position error signal acquired from a sixth position at the time of the access to one of the plurality of tracks in the second process, the sixth position is a closest fifth position among the plurality of fifth positions to the third position.

4. The disk device according to claim 2, the controller performs the determination of the plurality of second positions and the third position based on information in which the plurality of fifth positions are recorded.

5. The disk device according to any one of claims 1 to 4, the controller estimates a RRO correction value at the third position using RRO correction values at at least two of the plurality of second positions, and performs positioning of the head using the RRO correction value at the third position obtained by the estimation at the time of the access in the second process. ​

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