Magnetic disk apparatus and method

Abstract

To write a learned correction amount with high quality from the beginning of write start.SOLUTION: A magnetic disk device is provided with a magnetic disk in which positional information is written for each track, an assist unit for heating the magnetic disk, a magnetic head for reading and writing data to and from the magnetic disk, and a control unit for controlling the magnetic disk device, wherein the control unit causes the magnetic head to read the positional information written to the magnetic disk so as to learn the correction amount of a positional deviation occurring in synchronization with the rotation of the magnetic disk, and the control unit controls the magnetic disk device. A data pattern used for detecting a defective part of a magnetic disk is written by a magnetic head while heating a learning target part of the magnetic disk by supplying assist power to an assist unit, and a learned correction amount is written to the magnetic disk by the magnetic head while heating a write target part of the correction amount of the magnetic disk by supplying the assist power to the assist unit.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a magnetic disk device and method. [Background technology]

[0002] In magnetic disk drives that use a thermally assisted data writing method, it can take time for the quality of the data write to stabilize. Furthermore, during the manufacturing process of the magnetic disk drive, a process is sometimes performed in which the amount of correction for misalignment that occurs in synchronization with the rotation of the magnetic disk is learned and the learned amount of correction is written to the magnetic disk. In this case, the challenge is to improve the quality of the learned correction amount at the beginning of writing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 8593915 [Patent Document 2] Patent No. 8787125 [Patent Document 3] Patent No. 9620162 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment is to provide a magnetic disk device and method that can write data with a learned correction amount with higher quality than when writing first started. [Means for solving the problem]

[0005] The magnetic disk device of the embodiment is a magnetic disk device in which data is written using a thermal assist method, and includes a magnetic disk on which position information for each track is written, an assist unit that heats the magnetic disk, a magnetic head that reads and writes data from and to the magnetic disk, and a control unit that controls the magnetic disk device, and the control unit causes the magnetic head to read the position information written to the magnetic disk and learn the correction amount for position deviations that occur in synchronization with the rotation of the magnetic disk, supplies assist power to the assist unit to heat the learning target portion of the magnetic disk while causing the magnetic head to write a data pattern used to detect defective portions of the magnetic disk, and supplies assist power to the assist unit to heat the writing target portion of the magnetic disk while causing the magnetic head to write the learned correction amount to the magnetic disk. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a magnetic disk device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of the configuration of the magnetic head according to the embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of a servo pattern in which servo data is written on the magnetic disk according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the learning and writing of the RRO correction amount by the magnetic disk device according to the embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the magnetic head when learning the RRO correction amount and when writing data using the magnetic disk device according to the embodiment. [Figure 6] FIG. 6 is a flowchart illustrating an example of a procedure for writing an RRO code by the magnetic disk device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art or those that are substantially the same.

[0008] (Example of magnetic disk device configuration) 1 is a schematic diagram showing an example of the configuration of a magnetic disk device 1 according to an embodiment. The magnetic disk device 1 according to the embodiment is configured as, for example, an HDD (Hard Disk Drive). However, the magnetic disk device 1 according to the embodiment may be another type of magnetic disk device such as a hybrid HDD.

[0009] As shown in FIG. 1, the magnetic disk device 1 of the embodiment includes a magnetic disk 10, a spindle motor (SPM) 11, a magnetic head 12, an arm 13, a voice coil motor (VCM) 14, a driver IC (Integrated Circuit) 20, a head amplifier IC 30, a memory 70, and a system controller 100.

[0010] The spindle motor 11 holds the magnetic disk 10 and rotates the magnetic disk 10 around a spindle (not shown). A recording layer on which data can be recorded is formed on the magnetic disk 10. More specifically, the magnetic disk 10 has a plurality of concentric tracks centered on the center of rotation of the spindle motor 11, and data and the like can be written to these tracks.

[0011] The magnetic head 12 is mounted on the tip of an arm 13. The arm 13 is driven by a voice coil motor 14 connected to the other end thereof, which moves the magnetic head 12 to a predetermined position on the magnetic disk 10. This allows the magnetic head 12 to approach the recording surface of the magnetic disk 10 so as to be accessible. In other words, this allows the magnetic head 12 to record (write) data to and reproduce (read) data from the recording surface of the magnetic disk 10.

[0012] The magnetic disk device 1 may have a plurality of magnetic disks 10 held in parallel in the vertical direction by the spindle motor 11, and the recording surfaces of the magnetic disks 10 may be provided on both sides of the magnetic disks 10. In this case, the magnetic disk device 1 may have a plurality of magnetic heads 12 so that the number of magnetic heads 12 corresponds to the number of recording surfaces of the magnetic disks 10.

[0013] The system controller 100 is realized, for example, using a large scale integrated circuit (LSI) called a System-on-Chip (SoC), in which multiple elements are integrated on a single chip. The system controller 100 is connected to a host 200, and controls the entire magnetic disk device 1 based on commands from the host 200. The host 200 is configured as, for example, a processor, a personal computer, or a server.

[0014] The system controller 100 includes a read / write (R / W) channel 40 , a hard disk controller (HDC) 50 , and a microprocessor (MPU) 60 .

[0015] The R / W channel 40, HDC 50, and MPU 60 are electrically connected to each other, and the system controller 100 is electrically connected to the driver IC 20, head amplifier IC 30, and memory .

[0016] The R / W channel 40 is a signal processing circuit that processes signals related to reading / writing. The R / W channel 40 includes a read channel that performs signal processing on read data and a write channel that performs signal processing on write data. The read channel converts the read signal into digital data and demodulates the read data from the digital data. The write channel encodes write data transferred from the HDC 50 and transfers the encoded write data to the head amplifier IC 30.

[0017] The HDC 50 constitutes an interface between the magnetic disk device 1 and the host 200, and controls the transfer of read data and write data. That is, the HDC 50 functions as a host interface controller that sends and receives signals to and from the host 200. Signals transferred from the host 200 include commands such as write commands and read commands. The HDC 50 sends these commands received from the host 200 to the MPU 60.

[0018] In this way, in response to various instructions from the host 200, the HDC 50 controls the writing of data to the magnetic disk 10 and the reading of data from the magnetic disk 10 via the magnetic head 12, the head amplifier IC 30, the R / W channel 40, and the MPU 60.

[0019] The MPU 60 as a control unit is the main controller of the magnetic disk device 1, and includes a read / write (R / W) control unit 61 and an assist power control unit 62. The MPU 60 executes the processes of the R / W control unit 61, the assist power control unit 62, etc. on firmware. The MPU 60 may also include the R / W control unit 61, the assist power control unit 62, etc. as circuits.

[0020] The R / W control unit 61 controls data write and read processes in accordance with commands from the host 200. More specifically, when the R / W control unit 61 receives a write command from the host 200, for example, it executes a write process to write data to a predetermined area on the magnetic disk 10. When the R / W control unit 61 receives a read command from the host 200, for example, it executes a read process to read data from a predetermined area on the magnetic disk 10.

[0021] At this time, the R / W control unit 61 controls the VCM 14 via the driver IC 20 to position the magnetic head 12 at a target position on the magnetic disk 10 and executes the write or read process.

[0022] Here, the magnetic disk device 1 of the embodiment performs data write processing using, for example, a thermally assisted method. In the thermally assisted method, a write area of ​​a magnetic disk 10 having a high bit density is heated, thereby enabling writing to a medium with high thermal magnetic stability. The write area is heated by, for example, near-field light obtained by converting laser light. The magnetic head 12 described above is provided with a near-field light generating element that converts laser light into near-field light.

[0023] The assist power control unit 162 controls the head amplifier IC 30 so as to supply assist power to the configuration including the near-field light generating element provided in the magnetic head 12 .

[0024] The driver IC 20, under the control of the MPU 60, controls the driving of the spindle motor 11 and the voice coil motor 14. When the spindle motor 11 is driven, the magnetic disk 10 held by the spindle motor 11 rotates as described above. When the voice coil motor 14 is driven, the magnetic head 12 is positioned at a target track on the magnetic disk 10.

[0025] The head amplifier IC 30 supplies the magnetic head 12 with a write signal corresponding to the write data supplied from the R / W channel 40. The head amplifier IC 30 also controls the output of the laser light emitted to the near-field light generating element of the magnetic head 12 in accordance with instructions from the assist power control unit 162. The head amplifier IC 30 also amplifies the read signal output from the magnetic head 12 and transmits it to the R / W channel 40.

[0026] The memory 70 is configured to include a volatile memory, a non-volatile memory, etc. As an example, the memory 70 includes a buffer memory made up of a dynamic random access memory (DRAM), and a flash memory.

[0027] (Example of magnetic head configuration) 2 is a schematic diagram showing an example of the configuration of the magnetic head 12 according to the embodiment. As shown in FIG. 2, the magnetic head 12 is held by an arm 13 so as to face the recording layer 102 of the magnetic disk 10, and includes a write head 12W and a read head 12R.

[0028] The read head 12R includes a read element 121 that reads data from a recording layer 102 provided on a substrate 101 of the magnetic disk 10.

[0029] The write head 12W includes a main magnetic pole 122, an auxiliary magnetic pole 123, a coil 124, a laser diode 125, a waveguide 126, and a near-field light generating element 127.

[0030] The main pole 122 is made of a high-permeability material and generates a magnetic field perpendicular to the recording layer 102 of the magnetic disk 10, which is coated with a lubricant 103. The auxiliary pole 123 is magnetically joined to the main pole 122 and passes magnetic flux through the main pole 122. The coil 124 is wound around the auxiliary pole 123 and passes magnetic flux through the main pole 122. In this way, data can be written to the recording layer 102 of the magnetic disk 10 by generating a magnetic field in the main pole 122 using the coil 124.

[0031] The laser diode 125 is provided on, for example, the arm 13, and irradiates laser light toward the near-field light generating element 127 below. The waveguide 126 is provided between the laser diode 125 and the near-field light generating element 127, and guides the laser light irradiated from the laser diode 125 to the near-field light generating element 127. The near-field light generating element 127 converts the laser light from the laser diode 125 into near-field light, and irradiates the recording layer 102 of the magnetic disk 10 with the near-field light.

[0032] Near-field light is localized light that occurs near a microstructure that is smaller than the wavelength of light, and the diameter of the light spot is determined by the dimensions of the microstructure, not the wavelength of light. By using near-field light, a microscopic light spot can be generated, and a microscopic local area on the magnetic disk 10 can be heated.

[0033] As described above, in order to increase the bit density, a recording medium with high magnetic stability is used for the recording layer 102 of the magnetic disk 10. When writing data, a minute write area of ​​the recording layer 102 is heated, temporarily weakening the coercive force of such a recording medium with high magnetic stability, making it possible to write data to the magnetic disk 10.

[0034] (Example of magnetic disk configuration) During the manufacturing process, servo data used to position the magnetic head 12 is written to the magnetic disk 10. User data received from the host 200, metadata such as error correction codes associated with the user data, and system data can be written to each track area except for the area where the servo data is written.

[0035] The magnetic disk drive 1 stores in advance the settings for the positional relationships between a plurality of servo tracks and a plurality of data tracks. This allows the magnetic disk drive 1 to perform positioning control for positioning the magnetic head 12 on a target data track based on the servo data recorded on each servo track. The positioning control includes a seek operation for moving the magnetic head 12 in the radial direction toward the target data track, and a tracking operation for maintaining the magnetic head 12 on the target data track.

[0036] 3 is a schematic diagram showing an example of a servo pattern SV in which servo data is written on the magnetic disk 10 according to the embodiment. In the example of Fig. 3, the servo pattern SV is provided in the radial direction of the magnetic disk 10 across three tracks TRx to TRz. Note that the writing of servo data and other data by the magnetic head 12 onto the magnetic disk 10 is performed in the circumferential direction of the magnetic disk 10, that is, along each track.

[0037] As shown in FIG. 3, the servo pattern SV includes a preamble, a servo mark, a gray code, a burst, and an RRO (Repeatable Run Out) code, recorded in this order in the write / read direction, that is, in the circumferential direction of the magnetic disk 10.

[0038] The preamble is a single-cycle pattern data that changes periodically in the circumferential direction. The read head 12R reads the servo waveform, and the R / W channel 40 captures the read servo waveform as sampling data based on the servo clock. The preamble is used to adjust the amplitude, phase, and frequency of the sampling data.

[0039] The servo marks are pattern data for determining the timing of demodulating the servo data. Based on the timing of detecting the servo marks, the MPU 60 determines the timing of demodulating the various servo data read by the read head 12R thereafter.

[0040] The gray code is pattern data that includes an address for identifying each servo track provided on the magnetic disk 10.

[0041] The burst is pattern data used to detect the amount of positional deviation from the track center of the servo track indicated by the address included in the Gray code and to calculate a position error signal required for track following.

[0042] The RRO code is pattern data that encodes the amount of RRO correction. RRO is a positional deviation that occurs repeatedly in synchronization with the rotation of the magnetic disk 10. Although the ideal track shape is a perfect circle, distortion occurs in the servo track due to vibrations received during servo data writing and the quality of the servo pattern. Therefore, the radial position of the servo track specified by the burst may deviate from the radial position of the ideally shaped servo track. This positional deviation is called RRO because it occurs repeatedly by the same amount with each rotation of the magnetic disk 10.

[0043] The MPU 60 corrects the radial position of the magnetic head 12 obtained by reading the burst using the RRO correction amount recorded in the RRO code, thereby obtaining the radial position of the magnetic head 12 with the positional deviation due to RRO canceled.

[0044] (Example of RRO code write operation) Next, the RRO correction amount write operation by the magnetic disk device 1 according to the embodiment will be described with reference to FIGS.

[0045] In the manufacturing process of the magnetic disk device 1, after the gray code, bursts, etc. are written, learning and writing of the RRO correction amount are performed. In learning the RRO correction amount, for each track within a predetermined range, multiple tracks are sequentially set as target tracks, and for each target track, the difference between the actual radial position of the magnetic head 12 and the radial position of the target track is measured under positioning control based on the gray code and bursts.

[0046] That is, the MPU 60 reads the gray code and bursts using the read head 12R and estimates the position of the magnetic head 12 based on the read gray code and bursts. The MPU 60 also positions the magnetic head 12 on the target track based on the estimated position of the magnetic head 12. During this process, the MPU 60 obtains the amount of deviation of the estimated position of the magnetic head 12 from the target track as the RRO correction amount.

[0047] The RRO correction amount learned in this way is written as an RRO code to the track where it was learned.

[0048] As described above, the RRO correction amount is learned and written for each of a plurality of tracks within a predetermined range, and the RRO code is written to the entire servo pattern SV. After shipping, the magnetic disk device 1 can correct the read / write positions in real time by reading the RRO code as needed.

[0049] In the manufacturing process of the magnetic disk device 1 according to the embodiment, data patterns are written to the target tracks in parallel with learning the RRO compensation amount. That is, after learning and writing the RRO compensation amount for all tracks as described above, data patterns are written in the entire user data write area. The data patterns written during learning the RRO compensation amount are later used in a process called defect scan.

[0050] In the defect scan, data patterns are read from the entire area where user data is written. This makes it possible to extract areas where a decrease in read output due to defects or the like on the magnetic disk 10 is recognized. Areas where a decrease in read output is recognized are prohibited from use by the user.

[0051] 4 is a diagram showing an example of the learning and writing of the RRO correction amount by the magnetic disk device 1 according to the embodiment. As shown in FIG. 4, the magnetic disk device 1 performs the learning and writing of the RRO correction amount on tracks TR1 to TR2, for example. n (n is an integer of 6 or more), the RRO correction amount is learned and the learned RRO correction amount is written.

[0052] More specifically, the magnetic disk device 1 performs RRO correction amount learning and write operations on a track from the first track TR1 to the last track TR2. n The magnetic head 12 scans the tracks TR1 to TR2 by the read head 12R of the magnetic head 12. n At this time, as described above, the write head 12W of the magnetic head 12 writes data patterns to each of the tracks TR1 to TRn.

[0053] Last Track TR n When the learning of the RRO correction amount and the writing of the data pattern are completed, the magnetic disk device 1 reads the last track TR nThe magnetic head 12 scans from the first track TR1 to the first track TR2 in the opposite direction to that used for learning the RRO correction amount, and the write head 12W of the magnetic head 12 writes the learned RRO correction amount to the corresponding tracks TR3, TR4, and TR5. n ~Write to track TR1.

[0054] 5A to 5C are schematic diagrams showing the magnetic head 12 when learning and writing the RRO correction amount in the magnetic disk device 1 according to the embodiment. More specifically, FIGS. 5A to 5C show the state of the magnetic head 12 when learning the RRO correction amount. FIG. 5D shows the state of the magnetic head 12 when writing the RRO correction amount.

[0055] 5(a), the magnetic head 12 is moved to the start track of learning the RRO correction amount per cycle, and the read head 12R reads the gray code and burst of the servo pattern SV to start learning the RRO correction amount. At this time, in the magnetic disk device 1 of this embodiment, in order to write a data pattern in parallel with learning the RRO correction amount, the assist power control unit 162 supplies assist power to the laser diode 125 (see FIG. 2) to irradiate it with laser light, and the near-field light generating element 127 (see FIG. 2) generates near-field light NFL. Accordingly, an area of ​​the magnetic disk 10 close to the magnetic head 12 is locally heated, and the write head 12W also starts writing the data pattern.

[0056] As shown in Figure 5(b), during writing of a data pattern, a local region of the magnetic disk 10 is heated, causing the lubricant 103 covering the recording layer 102 of the magnetic disk 10 to decompose and vaporize, and to adhere to the magnetic head 12. The lubricant 103 is an organic solvent such as perfluoropolyether (PFPE), and the above-mentioned deposit Ma accumulates on the surface of the magnetic head 12 facing the magnetic disk 10 as the heating time of the magnetic disk 10 increases. Note that, based on the example of Figure 5, the surface of the magnetic head 12 facing the magnetic disk 10 may hereinafter also be referred to as the bottom surface of the magnetic head 12.

[0057] 5(c), deposits Ma of vaporized lubricant 103 solidify over time to become hardened material M. The deposits Ma include decomposition products of lubricant 103, and may also include SiO2, which is the oxidized Si component contained in the magnetic disk 10. The hardened material M formed by solidifying such deposits Ma is called buildup or smear, and is formed, for example, across substantially the entire gap from the lower surface of the magnetic head 12 to the outermost surface of the magnetic disk 10.

[0058] As described above, during the operations shown in FIGS. 5(a) to 5(c), the magnetic disk device 1 of the embodiment learns the RRO correction amount and writes a data pattern by moving the magnetic head 12 between the start track and the end track, and also promotes the formation of a hardened material M that reaches the top surface of the magnetic disk 10 from the underside of the magnetic head 12.

[0059] After moving to the end track, the magnetic head 12 reverses its movement direction and moves from the final track to the start track, writing the learned RRO correction amount to each corresponding track.

[0060] 5(d), at the final track position, the magnetic head 12 starts writing the learned RRO correction amount. Even when writing the RRO correction amount, the assist power control unit 162 supplies assist power to the laser diode 125, and the near-field light generating element 127 generates near-field light to locally heat the write area of ​​the magnetic disk 10. This temporarily reduces the thermally stable coercive force, making it possible to write the learned RRO correction amount.

[0061] Here, the cured material M formed from the lower surface of the magnetic head 12 to the outermost surface of the magnetic disk 10 is known to improve the transmittance of the near-field light NFL and the heat transfer efficiency. Therefore, when the cured material M is adhered to the magnetic head 12, the writing efficiency and writing accuracy of the magnetic head 12 are improved, and the effect of reducing the bit error rate (BER) of the data can be expected. As a result, the RRO correction amount data is written with a low BER and high quality.

[0062] The flying height of the magnetic head 12 above the surface of the magnetic disk 10 is set to an appropriate value in advance for each of data read, data write, and seek operations. However, when learning the RRO correction amount, the flying height of the magnetic head 12 is adjusted to the flying height for writing, not the flying height for reading. This allows a hardened material M of a size that matches the flying height for writing to be formed during RRO learning, and writing the RRO correction amount can be started with the hardened material M formed, reaching from the underside of the magnetic head 12 to the surface of the magnetic disk 10. Therefore, the RRO correction amount can be written with high quality from the start of writing.

[0063] However, the magnetic disk 10 may not be completely flat but may have some localized unevenness, which may cause the gap between the magnetic head 12 and the magnetic disk 10 to fluctuate while writing the RRO correction amount, resulting in a slight gap between the cured product M and the surface of the magnetic disk 10.

[0064] That is, when writing the RRO correction amount, if the magnetic head 12 moves to a region where the gap with the magnetic disk 10 is wider than the height of the hardened material M formed during learning of the RRO correction amount, a gap will occur between the hardened material M and the surface of the magnetic disk 10. Also, in a region where the gap between the magnetic head 12 and the magnetic disk 10 is narrower than the height of the hardened material M, the hardened material M formed on the lower surface of the magnetic head 12 will wear out, and then the magnetic head 12 will move to a region where the gap with the magnetic disk 10 is wider, which may cause a gap to occur between the hardened material M and the surface of the magnetic disk 10.

[0065] However, as the heating of the magnetic disk 10 continues, the hardened material M continues to accumulate even during the writing of the RRO correction amount. Therefore, gaps between the hardened material M and the surface of the magnetic disk 10, which are caused by minute irregularities on the surface of the magnetic disk 10, are relatively quickly filled with newly formed hardened material M. Therefore, high quality data writing is maintained throughout the entire period of writing the RRO correction amount.

[0066] Furthermore, the position on the magnetic disk 10 where writing of the RRO correction amount begins is the same as the position where learning of the RRO correction amount ends. Therefore, the size of the hardened object M is large enough to obtain sufficient accuracy in writing, and writing of the RRO correction amount can be started in a state where high-quality data writing is possible.

[0067] (Example of RRO code write processing) Next, an example of a write process of an RRO code in the magnetic disk device 1 according to the embodiment will be described with reference to Fig. 6. Fig. 6 is a flow diagram showing an example of a procedure of a write process of an RRO code by the magnetic disk device 1 according to the embodiment.

[0068] 6, the MPU 60 of the magnetic disk device 1 adjusts the flying height of the magnetic head 12 relative to the surface of the magnetic disk 10 so that the learning of the RRO correction amount and the write process are appropriate (step S101). The MPU 60 also performs servo calibration (step S102). That is, the MPU 60 optimizes various conditions so as to improve positioning accuracy.

[0069] The MPU 60 adjusts the amount of misalignment of the magnetic head 12 in the cross-track direction, i.e., the radial direction of the magnetic disk 10 (step S103). Similarly, the MPU 60 adjusts the amount of misalignment of the magnetic head 12 in the down-track direction, i.e., the read / write direction of the magnetic disk 10 (step S104). The amount of misalignment at this time is due to a misalignment between the built-in positions of the read head 12R and the write head 12W of the magnetic head 12, and in the processes of steps S103 and S104, the cross-track direction component and the down-track direction component of this misalignment are adjusted.

[0070] The MPU 60 learns the RRO correction amount of the magnetic head 12 on the start track, and writes a data pattern on the start track (step S105).

[0071] That is, the MPU 60 extracts a predetermined range of continuous tracks from the magnetic disk 10 and performs positioning measurements for multiple revolutions on the innermost or outermost track among them. This track corresponds to the start track in one RRO correction write process. The MPU 60 calculates the RRO from the positioning measurement results for each revolution on the start track, and further calculates the RRO correction amount from the calculated RRO. This allows learning of the RRO correction amount for the start track.

[0072] Furthermore, in parallel with the processing of step S105, the MPU 60 supplies assist power to the laser diode 125 to locally heat the target position on the start track, while causing the write head 12W to write a data pattern.

[0073] The MPU 60 executes these processes until it reaches the final track. That is, when the MPU 60 finishes learning the RRO correction amount and writing the data pattern for one track, it determines whether the track is the track that is the farthest from the start track in the cross-track direction among the consecutive tracks in the predetermined range that were initially extracted, that is, whether it is the final track of the multiple tracks in the predetermined range (step S106). If the track is not the final track (step S106: No), the MPU 60 repeats the process of step S105 for the next track adjacent in the cross-track direction.

[0074] If the track is the last track (step S106: Yes), the MPU 60 writes the RRO correction amount data obtained by learning a predetermined number of tracks in order from the last track to the start track (step S107).

[0075] The MPU 60 executes these processes for all tracks. That is, when the MPU 60 has completed learning and writing of the RRO correction amount for a predetermined number of tracks, it determines whether the above processes have been completed for all tracks of the magnetic disk 10 (step S108). If there are unprocessed tracks (step S108: No), the MPU 60 repeats the processes of steps S105 to S107 for the next predetermined number of tracks. If the above processes have been completed for all tracks (step S108: Yes), the MPU 60 ends the process.

[0076] This completes the RRO code write process by the magnetic disk device 1 of the embodiment.

[0077] (Comparative Example) There are known techniques for increasing the bit density of magnetic disks by using media with high thermal magnetic stability. In this case, a thermally assisted method may be used, in which near-field light or the like is used to locally heat the write area of ​​the magnetic disk during writing, temporarily weakening the coercivity of the media and allowing data to be written.

[0078] In thermally assisted magnetic disk devices, heating the magnetic disk can cause decomposition products from the magnetic disk to adhere to the magnetic head, forming a hardened material. Such hardened materials are known to improve the writing accuracy of the magnetic head, and there is a concern that the BER may worsen if the hardened material is not yet formed or if there is a gap between the magnetic head and the hardened material while it is still being formed.

[0079] Furthermore, in the manufacturing process of a magnetic disk drive, the following steps are performed on the magnetic disk: learning the RRO compensation amount, writing the RRO compensation amount, and writing a data pattern for detecting defective portions of the magnetic disk. The learning and writing of the RRO compensation amount are usually performed in parallel in one process, and the writing of the data pattern is usually performed in a process separate from the learning and writing of the RRO compensation amount.

[0080] When learning and writing the RRO correction amount, the RRO correction amount, which is a reproducible positional misalignment in which the same amount of misalignment repeatedly occurs between the magnetic head and the magnetic disk, is learned and written to the magnetic disk. As a result, when the magnetic disk device is actually operating, the RRO correction amount can be read from the magnetic disk and the magnetic head can be aligned.

[0081] At this time, it is preferable that the RRO correction amount be written as data with high quality. Therefore, at the beginning of writing the RRO correction, it is necessary to improve the deterioration of BER caused by the non-formation or incomplete formation of the cured material.

[0082] According to the magnetic disk device 1 of the embodiment, the RRO correction amount is learned, and the magnetic head 12 writes a data pattern used to detect defective portions of the magnetic disk 10 while supplying assist power to the laser diode 125 to heat the learning target portion of the magnetic disk 10. By writing the data pattern in parallel in this way, the magnetic disk 10 is heated even when learning the RRO correction amount, and a sufficient amount of hardened material M has already been formed by the time writing of the RRO correction amount begins. Therefore, the learned RRO correction amount can be written with higher quality than at the start of writing.

[0083] According to the magnetic disk device 1 of the embodiment, the set value of the flying height of the magnetic head 12 is the same when learning the RRO correction amount and when writing the RRO correction amount. By setting the flying height in this manner, the distance between the magnetic head 12 and the magnetic disk 10 is maintained approximately the same when learning and writing the RRO correction amount, and when writing the RRO correction amount, the occurrence of a gap between the magnetic disk 10 and the hardened material M formed on the magnetic head 12 when learning the RRO correction amount is suppressed.

[0084] According to the magnetic disk device 1 of the embodiment, the moving direction of the magnetic head 12 in the radial direction of the magnetic disk 10 is reversed when learning the RRO correction amount and when writing the RRO correction amount.

[0085] More specifically, when learning the RRO correction amount, the magnetic head 12 is moved from one track on one side of the radial direction of the magnetic disk 10 to the other track, and learning of the RRO correction amount for a predetermined number of tracks is sequentially performed. When writing the RRO correction amount, the magnetic head 12 is moved from the other track on one side of the radial direction of the magnetic disk 10 to the one track, and writing of the RRO correction amount for these tracks is sequentially performed.

[0086] When learning and writing the RRO compensation amount during the manufacturing process of a magnetic disk drive, typically, after learning the RRO compensation amount for a predetermined number of tracks, a seek operation is performed to move the magnetic disk to the initial start track where learning began, and then the magnetic disk is moved in the same direction as when learning the RRO compensation amount, and the RRO compensation amount is written from the start track to the end track. This procedure simplifies the control of learning and writing the RRO compensation amount.

[0087] However, in the case where the hardened material M is formed, for example, when learning the RRO correction amount, as in the magnetic disk device 1 of the embodiment, if a seek operation is performed between learning the RRO correction amount and writing, there is a risk that the hardened material M formed will be worn away due to minute irregularities on the magnetic disk 10.

[0088] As in the above configuration, the movement direction of the magnetic head 12 is reversed when learning the RRO correction amount and when writing the RRO correction amount, and a seek operation is not performed between learning the RRO correction amount and writing the RRO correction amount. This prevents the hardened material M formed when learning the RRO correction amount from wearing out before writing the RRO correction amount begins.

[0089] Although several embodiments of the present invention 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 embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0090] 1...magnetic disk device, 10...magnetic disk, 12...magnetic head, 12R...read head, 12W...write head, 60...microprocessor (MPU), 101...substrate, 102...recording layer, 103...lubricant, 125...laser diode, 126...waveguide, 127...near-field light generating element

Claims

1. A magnetic disk drive in which data is written by a thermally assisted method, A magnetic disk on which position information for each track is written, an assist unit that heats the magnetic disk; a magnetic head for reading and writing data from and to the magnetic disk; a control unit that controls the magnetic disk device, The control unit the position information written on the magnetic disk is read by the magnetic head to learn the correction amount for the position deviation that occurs in synchronization with the rotation of the magnetic disk, and the assist power is supplied to the assist unit to heat the learning target portion of the magnetic disk while the magnetic head writes a data pattern used to detect defective portions of the magnetic disk; supplying assist power to the assist unit to heat a target portion of the magnetic disk where the correction amount is to be written, while causing the magnetic head to write the learned correction amount to the magnetic disk; Magnetic disk device.

2. the set value of the flying height of the magnetic head is the same when learning the correction amount and when writing the correction amount; 2. The magnetic disk drive according to claim 1.

3. The control unit learning and writing the correction amount for each of a plurality of tracks adjacent to each other in a radial direction of the magnetic disk; a moving direction of the magnetic head in the radial direction is reversed between when learning the correction amount and when writing the correction amount; 2. The magnetic disk drive according to claim 1.

4. The control unit When learning the correction amount, the magnetic head is moved from a first track at one end side of the plurality of tracks in the radial direction toward a second track at the other end side, and learning of the correction amount for the plurality of tracks is sequentially performed; when writing the correction amount, the magnetic head is moved from the second track toward the first track, and the correction amount is written sequentially onto the plurality of tracks.

4. The magnetic disk drive according to claim 3.

5. A method performed in a magnetic disk drive that performs data writing using a thermally assisted method, comprising: a magnetic head reading position information for each track written on the magnetic disk, learning the amount of correction for positional deviation occurring in synchronization with the rotation of the magnetic disk, and writing a data pattern used to detect defective portions of the magnetic disk with the magnetic head while supplying assist power to an assist unit that heats the magnetic disk to heat a portion of the magnetic disk to be learned; writing the learned correction amount onto the magnetic disk by the magnetic head while supplying assist power to the assist unit to heat a target portion of the magnetic disk where the correction amount is to be written; method.

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