Thermally assisted magnetic recording / reproducing device and adjustment method thereof

Abstract

Maintains good write characteristics in a heat-assisted magnetic recording and playback device. [Solution] According to the embodiment, the adjustment method for a heat-assisted magnetic recording and playback device is an adjustment method for a heat-assisted magnetic recording and playback device equipped with a heat-assisted magnetic recording head and a heat-assisted magnetic recording medium, wherein the bit density in the starting area of ​​the recording band and in each area storing information other than user data is changed to be lower than the bit density of the areas other than the starting area in order to improve the write characteristics.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a thermally assisted magnetic recording and reproducing device and a method for adjusting the same. [Background technology]

[0002] In heat-assisted magnetic recording heads, a laser is used to raise the temperature of the magnetic disk for recording. It has been found that, due to the temperature rise, components thought to originate from the magnetic film of the magnetic disk adhere to the tip of the near-field optical element (NFT) via the lubricant, generating buildup. Build-up is unavoidable due to the nature of recording. On the other hand, it has been found that when build-up adheres to the head, it increases the laser transmittance and acts as a layer that improves the efficiency of laser transmission.

[0003] If the flying height is reduced, the build-up is removed by wear, and if the flying height is increased, the lubricant fills the gap between the head and the media and rebuilds it. Therefore, when the flying height changes within the disk surface, for example, when the head moves from a track with low flying height to a track with high flying height, the write performance decreases until the build-up is generated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 1,171,5493 [Patent Document 2] US Patent Application Publication No. 2023 / 0298621 [Patent Document 3] U.S. Patent No. 1,065,7987 Summary of the Invention [Problem to be solved by the invention]

[0005] Embodiments of the present invention aim to maintain good write characteristics in a heat-assisted magnetic recording and playback device. [Means for solving the problem]

[0006] According to an embodiment, a method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium is provided, characterized in that the bit density in the start area of ​​a shingled recording band and in each area storing information other than user data is changed to be lower than the bit density in areas other than the start area, thereby improving write characteristics. [Brief explanation of the drawings]

[0007] [Figure 1] This is a diagram illustrating the configuration of an example disk drive according to the sixth embodiment. [Figure 2] This is a partial exploded perspective view of a magnetic recording and playback device according to the sixth embodiment. [Figure 3] This is a side view showing the magnetic head and suspension. [Figure 4] This is a cross-sectional view of a write head and magnetic disk, which are part of a magnetic disk drive. [Figure 5] This diagram illustrates an example of the starting area for an SMR band. [Figure 6] This is a flowchart illustrating an LBA assignment method for executing the method according to the first embodiment. [Figure 7] This is a block diagram showing a part of the heat-assisted magnetic recording and playback device according to the seventh embodiment. [Figure 8] This is a flowchart illustrating an LBA assignment method for executing the method according to the second embodiment. [Figure 9] This is a block diagram showing a part of the heat-assisted magnetic recording and playback apparatus according to the eighth embodiment. [Figure 10] This is a flowchart illustrating an LBA assignment method for executing the method according to the third embodiment. [Figure 11]This is a block diagram showing a part of the heat-assisted magnetic recording and playback apparatus according to the ninth embodiment. [Figure 12] This is a flowchart illustrating an LBA assignment method for executing the method according to the fourth embodiment. [Figure 13] This is a block diagram showing a part of the heat-assisted magnetic recording and playback apparatus according to the 10th embodiment. [Figure 14] This is a flowchart illustrating an LBA assignment method for executing an example of the method according to the fifth embodiment. [Figure 15] This is a flowchart illustrating an LBA assignment method for performing another example of the method according to the fifth embodiment. [Figure 16] This diagram illustrates examples of areas that store information other than user data. [Figure 17] This diagram illustrates examples of areas that store information other than user data. DETAILED DESCRIPTION OF THE INVENTION

[0008] The method for adjusting a thermally-assisted magnetic recording and reproducing device according to the embodiment is a method for adjusting a thermally-assisted magnetic recording and reproducing device equipped with a thermally-assisted magnetic recording head and a thermally-assisted magnetic recording medium, and improves write characteristics in the start area of ​​a shingled magnetic recording (SMR) band and in each area storing information other than user data. Depending on the process for improving the write characteristics, this adjustment method can be divided into the following first to fifth embodiments.

[0009] In the adjustment method for the heat-assisted magnetic recording and playback apparatus according to the first embodiment, the write characteristics are improved by changing the BPI (bits per square inch) to a lower value than that of the areas other than the starting area. In the adjustment method for the heat-assisted magnetic recording and playback apparatus according to the second embodiment, the write characteristics are improved by strengthening the Track ECC (error correcting code) by changing the parity number to a higher number than that of the Track ECC (error correcting code) in areas other than the starting area, thereby increasing the parity number. In the adjustment method for the heat-assisted magnetic recording and playback apparatus according to the third embodiment, the light characteristics are improved by changing the laser current or light current to a higher value than the laser current or light current in areas other than the starting area. In the adjustment method for the heat-assisted magnetic recording and playback apparatus according to the fourth embodiment, the write characteristics are improved by lowering the TPI (tracks per inch) to a lower level than that of areas other than the starting area. In the adjustment method for the heat-assisted magnetic recording and playback apparatus according to the fifth embodiment, the writing characteristics are improved by lowering or raising the amount of levitation of the heat-assisted magnetic recording head compared to areas other than the starting area, for example, by gradually increasing it for each track.

[0010] Furthermore, the heat-assisted magnetic recording and playback apparatus according to the embodiment is an apparatus for carrying out the adjustment method of the heat-assisted magnetic recording and playback apparatus according to the above embodiment, and includes a heat-assisted magnetic recording head equipped with a main magnetic pole, a near-field optical element that generates near-field light, a waveguide for propagating light to the near-field optical element, and a light source that supplies light to the waveguide; a heat-assisted magnetic recording medium having a lubricant layer on the recording surface facing the heat-assisted magnetic recording head; a change instruction unit that instructs the change of setting values ​​of each parameter in a process for improving write characteristics in the SMR band start area and each area storing information other than user data; and a control unit that controls the change of setting values ​​of each parameter in a process for improving write characteristics in the SMR band start area and each area storing information other than user data, based on information from the change instruction unit. The heat-assisted magnetic recording and playback apparatus according to the embodiment can be divided into the following sixth to tenth embodiments, corresponding to the adjustment methods of the first to fifth embodiments.

[0011] In the heat-assisted magnetic recording and playback apparatus according to the sixth embodiment, the parameter setting value is the BPI, the change instruction unit is the BPI change instruction unit, and the control unit is the format control unit. In the heat-assisted magnetic recording and playback apparatus according to the seventh embodiment, the parameter setting value is the track ECC, the change instruction unit is the track ECC change instruction unit, and the control unit is the format control unit. In the heat-assisted magnetic recording and playback apparatus according to the eighth embodiment, the parameter setting value is the laser current or the write current, the change instruction unit is the laser current or write current change instruction unit, and the control unit is the format control unit. In the heat-assisted magnetic recording and playback apparatus according to the ninth embodiment, the parameter setting value is TPI, the change instruction unit is a TPI change instruction unit, and the control unit is a servo control unit. In the heat-assisted magnetic recording and playback apparatus according to the 10th embodiment, the parameter setting value is the levitation amount, the change instruction unit is the levitation amount change instruction unit, and the control unit is the levitation amount control unit.

[0012] According to the first to tenth embodiments, corrections can be applied in advance to ensure sufficient write characteristics in areas with a high risk of write errors due to build-up reduction, such as the starting area of ​​the SMR band and areas storing information other than user data. This avoids the risk of read errors. As a result, good write characteristics can be maintained in the thermally assisted magnetic recording and playback device.

[0013] Areas that are written with a low build-up height and are at risk of read errors are areas that are likely to be the start of a write operation. Specifically, these include the start of a write operation in the SMR band area, or areas used periodically within the controller firmware (FW) independently of user data, such as the ATI management area, media cache area, system area, and area for measuring read / write (RW) characteristics. The system area here refers to an area that stores information necessary to control the magnetic recording and reproducing device. This information is separate from the data received from the host.

[0014] The area for improving the write characteristics can be an area of ​​one or more tracks. In addition to lowering the BPI, which is a common process for improving write characteristics, increasing the number of parities in the track ECC can also improve performance. Another method is to increase the laser current, write current, or both, while lowering the TPI. It is also possible to improve performance by lowering or increasing the flying height. Furthermore, if the flying height is increased, gradually increasing it one track at a time can ensure build-up in areas that are not corrected.

[0015] Example Example 1 Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are easily conceivable by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0016] First, the configuration of an example of a disk drive according to the sixth embodiment will be described with reference to Fig. 1. The configuration of the disk drive, which is a magnetic recording and reproducing device, shown in Fig. 1 is also applied to each of the embodiments described below. As shown in FIG. 1, the disk drive 200 is a magnetic disk device of the perpendicular magnetic recording type that incorporates a magnetic disk 1, which is a perpendicular magnetic recording medium, and a magnetic head 10 having a magnetic flux control layer, which will be described later.

[0017] FIG. 2 is a partial exploded perspective view of the magnetic recording and reproducing device according to the sixth embodiment. Figure 2 shows a magnetic recording and playback apparatus according to the sixth embodiment, in which a plurality of magnetic disks 1 and a plurality of magnetic heads 10 are housed within a housing 51, with the lid omitted. The magnetic disk 1 is fixed to a spindle motor (SPM) 2 and mounted for rotational motion. The magnetic head 10 is mounted on an actuator 3 and configured to move in a radial direction on the magnetic disk 1. The actuator 3 is rotationally driven by a voice coil motor (VCM) 4. In FIG. 1, for example, the magnetic head 10 is shown seeking to a first position on the recording surface 1a, while the magnetic head 10' mounted on the actuator 3' is shown seeking to a second position that is a radially different position from the first position. The magnetic head 10 includes a write head 10W, a read head 10R, and a thermal assist unit 100. The write head 10W writes data to the magnetic disk 1. The read head 10R reads data from the magnetic disk 1. The thermal assist unit 100 assists the write head 10W in writing data to the magnetic disk 1. The magnetic head 10 may include a single magnetic head or multiple magnetic heads.

[0018] Furthermore, the disk drive has a head amplifier integrated circuit (hereinafter referred to as head amplifier IC) 11, a read / write channel (R / W channel) 12, a hard disk controller (HDC) 13, a microprocessor (MPU) 14-1, a driver IC 16, and memory 17. The R / W channel 12, HDC 13, and MPU 14 are incorporated into a controller 15 consisting of a single integrated circuit chip. As will be described later, the head amplifier IC11 includes a group of circuits for driving a laser diode for thermal assist. Furthermore, the head amplifier IC11 includes a driver that supplies the recording head 10W with a recording signal (write current) corresponding to write data supplied from the R / W channel 12. The head amplifier IC11 also includes a read amplifier that amplifies the read signal output from the reproducing head 10R and transmits it to the R / W channel 12.

[0019] The R / W channel 12 is a signal processing circuit for read / write data. The HDC 13 constitutes an interface between the disk drive and the host 18, and controls the transfer of read / write data. The MPU 14-1 is the main control unit of the disk drive, and executes servo control necessary for controlling read / write operations and positioning the magnetic head 10. The MPU 14-1 also includes a BPI change instruction unit 71 that instructs a change in the BPI in the start area of ​​the SMR band and in each area storing information other than user data, and a format control unit 72 that, based on information from the BPI change instruction unit 71, changes the BPI in the start area of ​​the SMR band and in each area storing information other than user data to a lower value than in areas other than the start area, thereby improving write characteristics. The memory 17 includes a buffer memory made up of a DRAM, a flash memory, and the like.

[0020] FIG. 3 is a side view showing the magnetic head 10 and the suspension. As shown in Fig. 3, each magnetic head 10 is configured as a floating-type head and includes a substantially rectangular parallelepiped slider 42 and a recording / reproducing head portion 44 provided at the trailing end of the slider 42. The magnetic head 10 is fixed to a gimbal spring 41 provided at the tip of a suspension 34. A head load L is applied to each magnetic head 10 toward the surface of the magnetic disk 1 due to the elasticity of the suspension 34. As shown in Fig. 2, each magnetic head 10 is connected to a head amplifier IC 11 and an HDC 13 via a wiring member (flexure) 35 fixed on the suspension 34 and an arm.

[0021] Next, the configurations of the magnetic disk 1 and the magnetic head 10 will be described in detail. FIG. 4 is a cross-sectional view of the write head 10W and the magnetic disk 1, which are part of the magnetic disk device. The magnetic disk 1 has a substrate 20, a heat sink layer 21, a crystalline orientation layer 22, a perpendicular recording layer 23, and a protective film 24, which are sequentially stacked on the substrate 20 and have a lubricant layer formed on the surface. The perpendicular recording layer 23 has large anisotropy in the direction perpendicular to the disk surface. The crystalline orientation layer 22 is disposed below the perpendicular recording layer 23 to improve the orientation of the perpendicular recording layer 23. The heat sink layer 21 is disposed below the crystalline orientation layer 22 to suppress the expansion of the heated region. The protective film 24 is disposed on top of the perpendicular recording layer 23 to protect it.

[0022] The magnetic head 10 is a separated magnetic head in which the recording head 10W and the reproducing head 10R are separated. The recording head 10W comprises a main pole 40 made of a high-permeability material that generates a magnetic field perpendicular to the disk surface, a trailing yoke 50 magnetically joined to the main pole that passes magnetic flux to the main pole 40, a return shield pole 60 disposed on the leading side of the main pole 40 to efficiently close the magnetic path directly below the main pole, a coil 70 disposed so as to wrap around the magnetic path including the trailing yoke and return shield pole to pass magnetic flux to the main pole 40, a heater 80 for controlling the flying height of the recording head, and a near-field optical element 30 disposed on the leading side of the main pole 40 that generates near-field light that heats the perpendicular recording layer 23 of the magnetic disk 1, and a waveguide 31 for propagating the light for generating near-field light. The light source is a laser diode 32 mounted on the slider of the actuator assembly 3. For example, Au, Pd, Pt, Rh, or Ir, or an alloy made of a combination of some of these, can be used for the near-field light element 30. For example, an oxide made of SiO2, Al2O3, or the like can be used for the insulating layer provided between the main pole and the near-field light element.

[0023] The write current is a current that can be used for data recording, such as the current applied to the magnetic coil of the recording head when recording data. The light source drive current is a current that causes the light source to emit light. For example, a laser light source can be used as the light source. Examples of heat-assisted magnetic recording methods usable in the magnetic disk drive 200 include the conventional recording method, known as CMR (Conventional Magnetic Recording), in which tracks are written with radial spacing so that adjacent tracks do not overlap; the shingled magnetic recording method, known as SMR (Shingled Magnetic Recording), which has tracks stacked sequentially in the radial direction and records by overlapping parts of adjacent tracks; the interlaced magnetic recording method, known as IMR (Interlaced Magnetic Recording), which has a bottom track and a top track with adjacent tracks stacked alternately, and records on the bottom track after recording on the bottom track by overlapping the interlaced top track; or combinations thereof.

[0024] Furthermore, if a change in BPI, track ECC, laser current or write current, TPI, or flying height is detected, the host 18 can be notified. At this time, the SMART (Self-Monitoring Analysis and Reporting Technology) function can be used to notify the host 18.

[0025] The adjustment method for the heat-assisted magnetic recording and playback apparatus according to the first embodiment is an adjustment method for a heat-assisted magnetic recording and playback apparatus equipped with a heat-assisted magnetic recording head and a heat-assisted magnetic recording medium, wherein the bit density in the starting area of ​​the SMR band and each area storing information other than user data is changed to a lower bit density than the bit density of the areas other than the starting area in order to improve the write characteristics.

[0026] The method for adjusting the thermally assisted magnetic recording and reproducing device of the first embodiment can be applied to the thermally assisted magnetic recording and reproducing device of the sixth embodiment, and the thermally assisted magnetic recording and reproducing device of the sixth embodiment includes a thermally assisted magnetic recording head having a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on the recording surface facing the thermally assisted magnetic recording head; a bit density change instruction unit that instructs a change in bit density in the start area of ​​the SMR band and in each area storing information other than user data; and a format control unit that, based on information from the bit density change instruction unit, changes the bit density in the start area of ​​the shingled magnetic recording (SMR) band and in each area storing information other than user data to be lower than that of areas other than the start area, thereby improving write characteristics.

[0027] Figure 5 shows a diagram illustrating an example of the SMR band's starting area. As shown in the figure, a guard band 61-2 is provided between one shingled band 62-1 and an adjacent band 62-2. Band 62-1 is provided with tracks N, N+1, N+2, N+3, N+4, and N+5 that are shingled in the write direction indicated by arrow C1. Guard band 61-2 is provided with tracks M, M+1, M+2, M+3, M+4, and M+5 that are shingled in the write direction indicated by arrow C2. Guard band 61-2 is spaced a short distance from tracks N+5 and M on either side of it, and is not shingled. Guard band 61-1 is provided on the opposite side of guard band 61-2 across shingled band 62-1, and guard band 61-3 is provided on the opposite side of guard band 61-2 across shingled band 62-2, and each is spaced a short distance from the tracks on either side, and is not shingled. The area indicated by arrow 63-1 is the starting area of ​​band 62-1, and the area indicated by arrow 63-2 is the starting area of ​​band 62-2.

[0028] Figure 6 shows a flowchart illustrating the logical block address (LBA) assignment process for executing the adjustment method using the magnetic recording and playback apparatus according to the first embodiment. Example 1 shows an example of an adjustment method using the magnetic recording and playback device according to the first embodiment, in which the BPI in the starting area of ​​the SMR band is changed to a lower BPI than that of the areas other than the starting area in order to improve the write characteristics. Prepare magnetic disks with fixed capacities based on the premise of reducing the BPI, and begin allocating LBAs. First, determine the band areas to be used, for example, bands 62-1 and 62-2 in Figure 5 (ST1). Next, determine the LBAs for the areas where the BPI will be reduced, for example, starting areas 63-1 and 63-2 (ST2). After that, determine the LBAs for the entire system (ST3). Next, the BPI change instruction unit 71 instructs a BPI change. Furthermore, the format control unit 72 changes the BPI of the starting areas 63-1 and 63-2 to be about 10% lower than the BPI of the areas other than the starting areas 63-1 and 63-2 in order to improve the write characteristics.

[0029] According to this embodiment, in areas where there is a risk of read errors due to writing with a low build-up height, a correction can be applied in advance to ensure sufficient write characteristics. This makes it possible to avoid the risk of read errors and maintain good write characteristics in the heat-assisted magnetic recording and playback device.

[0030] The magnetic disk 1 included in the magnetic recording / reproducing device 200 according to the embodiment can use a perpendicular magnetic recording medium. The perpendicular magnetic recording medium can include, for example, a magnetic recording layer with a granular structure. The magnetic recording layer with a granular structure includes magnetic particles having an L10 structure as the magnetic material. Examples of magnetic particles having an L10 structure include FePt alloy particles and CoPt alloy particles. The grain boundaries can include grain boundary materials such as C, BN, and oxides containing SiO2. The buildup is thought to be a hardened substance formed when siloxane gas floating within the magnetic recording / reproducing device or components derived from the magnetic recording layer, such as SiO2 contained in the grain boundaries, adheres to the tip of the NFT via a lubricant. A protective layer can also be provided on the magnetic recording layer. Examples of the protective layer include carbon (C), diamond-like carbon, SiO2, and ZrO2. Examples of lubricants that can be applied to the recording surface of the magnetic disk include perfluoropolyether, fluorinated alcohol, and fluorinated carboxylic acid.

[0031] Example 2 Example 2 shows an example of a method for adjusting a heat-assisted magnetic recording and playback apparatus according to the second embodiment. The method for adjusting a thermally assisted magnetic recording and reproducing device according to the second embodiment is a method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, and in the start area of ​​the SMR band and in each area storing information other than user data, the track ECC is strengthened by changing the parity number to a number higher than the parity number of the track ECC in areas other than the start area, thereby increasing the parity number, thereby improving write characteristics.

[0032] The adjustment method for the heat-assisted magnetic recording and playback apparatus according to the second embodiment can be the heat-assisted magnetic recording and playback apparatus according to the seventh embodiment. The thermally assisted magnetic recording and reproducing device of the seventh embodiment includes a thermally assisted magnetic recording head having a main pole, a near-field optical element that generates near-field light, a waveguide that propagates light to the near-field optical element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on the recording surface facing the thermally assisted magnetic recording head; a track error correction code change instruction unit that instructs a change of the track error correction code (increases the number of parities) in the start area of ​​the shingled recording band and in each area storing information other than user data; and a format control unit that, based on information from the track error correction code change instruction unit, changes the parity number of the track error correction code in the start area of ​​the shingled recording band and in each area storing information other than user data to a higher number than the parity number of the track error correction code in areas other than the start area, thereby strengthening the track error correction code (increases the number of parities) and improving write characteristics.

[0033] An example of a thermally assisted magnetic recording and reproducing device according to the seventh embodiment has the same configuration as that shown in FIG. 1, except that an MPU 14-2 including a change instruction unit 73 and a format control unit 72 shown in FIG. 7 is provided instead of the MPU 14-1. FIG. 8 is a flowchart showing a logical block address (LBA) allocation process for executing the method for adjusting a magnetic recording and reproducing device according to the second embodiment. A magnetic disk with a capacity determined in advance based on the assumption that the track ECC will be strengthened is prepared, and LBA allocation begins. First, the band area to be used is determined, for example, bands 62-1 and 62-2 in Figure 5 (ST11). Next, the LBAs of the areas where the track ECC will be lowered, for example, start areas 63-1 and 63-2, are determined (ST12). After that, the entire LBA is determined (ST13).

[0034] Next, a track ECC change is instructed by the track ECC change instructing unit 73. Furthermore, the format control unit 72 changes and strengthens the track ECC of the start areas 63-1 and 63-2 to twice the amount of the track ECC of the areas other than the start areas 63-1 and 63-2, thereby improving the write characteristics.

[0035] According to this embodiment, in areas where there is a risk of read errors due to writing with a low build-up height, a correction can be applied in advance to ensure sufficient write characteristics. This makes it possible to avoid the risk of read errors and maintain good write characteristics in the heat-assisted magnetic recording and playback device.

[0036] Example 3 Example 3 shows an example of a method for adjusting the thermally assisted magnetic recording and reproducing device according to the third embodiment. The adjustment method for a heat-assisted magnetic recording and playback apparatus according to the third embodiment is an adjustment method for a heat-assisted magnetic recording and playback apparatus equipped with a heat-assisted magnetic recording head and a heat-assisted magnetic recording medium, wherein the laser current or write current in the starting area of ​​the SMR band and each area storing information other than user data is changed to a higher laser current or write current than that of the areas other than the starting area in order to improve the write characteristics.

[0037] The thermally assisted magnetic recording and reproducing device according to the eighth embodiment can be used in the method for adjusting the thermally assisted magnetic recording and reproducing device according to the third embodiment. The heat-assisted magnetic recording and playback apparatus according to the eighth embodiment includes a heat-assisted magnetic recording head equipped with a main magnetic pole, a near-field optical element that generates near-field light, a waveguide for propagating light to the near-field optical element, and a light source that supplies light to the waveguide; a heat-assisted magnetic recording medium equipped with a lubricant layer on the recording surface facing the heat-assisted magnetic recording head; a laser current or write current change instruction unit that instructs a change in the laser current or write current in the starting area of ​​the recording band and each area storing information other than user data; and a format control unit that, based on information from the laser current or write current change instruction unit, increases the laser current or write current in the starting area of ​​the recording band and each area storing information other than user data to be higher than the laser current or write current in areas other than the starting area in order to improve the write characteristics.

[0038] An example of a thermally assisted magnetic recording and reproducing device according to the eighth embodiment has the same configuration as that shown in FIG. 1, except that instead of MPU 14-1, MPU 14-3 including a laser current or write current change instruction unit 74 and a format control unit 72 shown in FIG. 9 is provided. FIG. 10 is a flowchart showing a logical block address (LBA) allocation process for executing the method for adjusting a magnetic recording and reproducing device according to the third embodiment. A magnetic disk is prepared, and LBA allocation begins. First, the band area to be used is determined, for example, bands 62-1 and 62-2 in Figure 5 (ST21). Next, the LBAs of the areas where the laser current or write current will be increased, for example, start areas 63-1 and 63-2, are determined (ST22). After that, the entire LBA is determined (ST23).

[0039] Next, the laser current or light current change instruction unit 74 instructs a change in the laser current or light current. Furthermore, the format control unit 72 changes the laser current or light current in the starting areas 63-1 and 63-2 to 5% higher than the laser current or light current in areas other than the starting areas 63-1 and 63-2 to improve the light characteristics. According to this embodiment, in areas where there is a risk of read errors due to writing with a low build-up height, a correction can be applied in advance to ensure sufficient write characteristics. This makes it possible to avoid the risk of read errors and maintain good write characteristics in the heat-assisted magnetic recording and playback device.

[0040] Example 4 Example 4 shows an example of a method for adjusting the thermally assisted magnetic recording and reproducing device according to the fourth embodiment. The adjustment method for a heat-assisted magnetic recording and playback apparatus according to the fourth embodiment is an adjustment method for a heat-assisted magnetic recording and playback apparatus equipped with a heat-assisted magnetic recording head and a heat-assisted magnetic recording medium, wherein the TPI is lowered in the starting area of ​​the SMR band and in each area storing information other than user data compared to the TPI of areas other than the starting area, thereby improving the write characteristics.

[0041] The thermally assisted magnetic recording and reproducing device according to the ninth embodiment can be used in the method for adjusting the thermally assisted magnetic recording and reproducing device according to the fourth embodiment. The thermally assisted magnetic recording and reproducing device of the ninth embodiment includes a thermally assisted magnetic recording head having a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on the recording surface facing the thermally assisted magnetic recording head; a track density change instruction unit that instructs a change in track density (TPI) in the start area of ​​the shingled recording band and in each area storing information other than user data; and a servo control unit that, based on information from the track density change instruction unit, reduces the track density in the start area of ​​the shingled recording band and in each area storing information other than user data compared to areas other than the start area, thereby improving write characteristics.

[0042] An example of a heat-assisted magnetic recording and playback apparatus according to the ninth embodiment has the same configuration as in Figure 1, except that instead of the MPU 14-1, an MPU 14-4 is provided, which includes the TPI change instruction unit 75 and the format control unit 72 shown in Figure 11. FIG. 12 is a flow diagram showing a logical block address (LBA) allocation process for executing the method for adjusting a magnetic recording and reproducing device according to the fourth embodiment. Prepare the magnetic disk and begin LBA allocation. First, determine the band areas to be used, for example, bands 62-1 and 62-2 in Figure 5 (ST31). Next, determine the LBAs for the areas to lower the TPI, for example, starting areas 63-1 and 63-2 (ST32). After that, determine the overall LBA (ST33).

[0043] Next, the TPI change instruction unit 75 instructs a change to lower the TPI. Furthermore, the servo control unit 76 and the format control unit 72 change the TPI of the starting areas 63-1 and 63-2 to 2% lower than the TPI of the areas other than the starting areas 63-1 and 63-2 to improve the lighting characteristics. According to this embodiment, in areas where there is a risk of read errors due to writing with a low build-up height, a correction can be applied in advance to ensure sufficient write characteristics. This makes it possible to avoid the risk of read errors and maintain good write characteristics in the heat-assisted magnetic recording and playback device.

[0044] Example 5 Example 5 shows an example of a method for adjusting the thermally assisted magnetic recording and reproducing device according to the fifth embodiment. The adjustment method for a heat-assisted magnetic recording and playback apparatus according to the fifth embodiment is an adjustment method for a heat-assisted magnetic recording and playback apparatus equipped with a heat-assisted magnetic recording head and a heat-assisted magnetic recording medium, wherein the amount of levitation of the heat-assisted magnetic recording head is lowered in the starting area of ​​the SMR band and in each area storing information other than user data compared to areas other than the starting area, or the amount of levitation is increased, for example, little by little for each track, to improve the write characteristics.

[0045] The thermally assisted magnetic recording and reproducing device according to the tenth embodiment can be used in the method for adjusting the thermally assisted magnetic recording and reproducing device according to the fifth embodiment. The heat-assisted magnetic recording and playback apparatus according to the 10th embodiment includes a heat-assisted magnetic recording head equipped with a main magnetic pole, a near-field optical element that generates near-field light, a waveguide for propagating light to the near-field optical element, and a light source that supplies light to the waveguide; a heat-assisted magnetic recording medium equipped with a lubricant layer on the recording surface facing the heat-assisted magnetic recording head; a floating amount change instruction unit that instructs a change in the floating amount in the starting area of ​​the tile recording band and each area storing information other than user data; and a floating amount control unit that, based on information from the floating amount change instruction unit, lowers the floating amount in the starting area of ​​the tile recording band and each area storing information other than user data compared to areas other than the starting area (and raises it little by little for each track) to improve the writing characteristics.

[0046] An example of a heat-assisted magnetic recording and playback apparatus according to the 10th embodiment has the same configuration as in Figure 1, except that instead of the MPU 14-1, an MPU 14-5 is provided, which includes a levitation amount change instruction unit 78 and a levitation amount control unit 79 as shown in Figure 13. Figure 14 shows a flowchart illustrating a logical block address (LBA) assignment process for performing an example of the adjustment method for a magnetic recording and playback device according to the fifth embodiment. Prepare the magnetic disk and begin assigning LBAs. First, determine the band areas to be used, for example, bands 62-1 and 62-2 in Figure 5 (ST51). Next, determine the LBAs for the areas where the rise amount will be reduced, for example, starting areas 63-1 and 63-2 (ST52). After that, determine the overall LBA (ST53).

[0047] Next, the float amount change instruction unit 78 instructs a change to reduce the float amount. Furthermore, the float amount control unit 79 changes the float amount in starting areas 63-1 and 63-2 to 10% lower than the float amount in areas other than starting areas 63-1 and 63-2 to improve the light characteristics. Also, the flying height change instruction unit 78 can instruct the flying height to be lowered once and then gradually increased one track at a time. Furthermore, the flying height control unit 79 can improve the write characteristics by lowering the flying height of the start areas 63-1 and 63-2 and then gradually increasing the flying height of the areas other than the start areas 63-1 and 63-2 once and then increasing it one track at a time, thereby ensuring build-up in areas that are not corrected.

[0048] Figure 15 shows a flowchart illustrating the logical block address (LBA) assignment process for performing another example of the adjustment method for the magnetic recording and reproducing apparatus according to the fifth embodiment. Prepare the magnetic disk and begin assigning LBAs. First, determine the band areas to be used, for example, bands 62-1 and 62-2 in Figure 5 (ST41). Next, determine the LBAs for the areas where the rise will be increased, for example, starting areas 63-1 and 63-2 (ST42). After that, determine the overall LBA (ST43).

[0049] Next, a change to increase the flying height is instructed by flying height change instruction unit 78. Furthermore, flying height control unit 79 changes the flying height of start areas 63-1 and 63-2 to be about 10% higher than the flying height of areas other than start areas 63-1 and 63-2, thereby improving write characteristics. According to this embodiment, in areas where there is a risk of read errors due to writing with a low build-up height, a correction can be applied in advance to ensure sufficient write characteristics. This makes it possible to avoid the risk of read errors and maintain good write characteristics in the heat-assisted magnetic recording and playback device. In the first to fifth embodiments, examples have been shown in which the write characteristics are improved in the start area of ​​the SMR band, but the write characteristics are improved in each area in which information other than user data is stored.

[0050] 16 and 17 show examples of areas storing information other than user data. As shown in FIG. 16, the ATI management area and the media cache area can be provided in an area 82-1 that is a part of a correction track 83-1 between user areas 81 and adjacent user areas 81, for example. As shown in FIG. 17, the system area can be provided in a correction area 83-1 between two adjacent user areas 84, for example.

[0051] 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]

[0052] 1...magnetic disk, 1a...recording surface, 10, 10W, 10R...thermally assisted magnetic recording head, 30...near-field optical element, 31...waveguide, 32...light source, 40...main pole, 200...thermally assisted magnetic recording / reproducing device, 71...bit density change instruction unit, 72...format control unit, 73...track error correction code change instruction unit, 74...laser current or write current change instruction unit, 75...track density change instruction unit, 76...servo control unit, 78...flying height change instruction unit, 79...flying height control unit

Claims

1. A method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, comprising: A method for adjusting a thermally assisted magnetic recording and reproducing device, characterized by improving write characteristics by changing the bit density in the start area of ​​a shingled recording band and in each area storing information other than user data to be lower than the bit density in areas other than the start area.

2. A method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, comprising: A method for adjusting a thermally assisted magnetic recording and reproducing device, characterized by changing the parity number of the track error correction code in the start area of ​​a shingled recording band and in each area storing information other than user data to be higher than the parity number of the track error correction code in areas other than the start area, thereby strengthening the track error correction code and improving write characteristics.

3. A method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, comprising: A method for adjusting a thermally assisted magnetic recording and reproducing device, characterized by improving write characteristics by changing the laser current or write current in the start area of ​​a shingled recording band and in each area storing information other than user data to be higher than the laser current or write current in areas other than the start area.

4. A method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, comprising: A method for adjusting a thermally assisted magnetic recording and reproducing device, characterized in that the track density in the start area of ​​a shingled recording band and in each area storing information other than user data is reduced below the track density in areas other than the start area, thereby improving write characteristics.

5. A method for adjusting a thermally assisted magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a thermally assisted magnetic recording medium, comprising: A method for adjusting a thermally assisted magnetic recording and reproducing device, characterized by lowering or raising the flying height of the thermally assisted magnetic recording head in the start area of ​​a shingled recording band and in each area storing information other than user data compared to the flying height of the thermally assisted magnetic recording head in areas other than the start area, thereby improving write characteristics.

6. a thermally assisted magnetic recording head including a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on a recording surface facing a thermally assisted magnetic recording head; a bit density change instruction unit that instructs a change in bit density in a start area of ​​a shingled recording band and in each area storing information other than user data; and a format control unit that, based on information from the bit density change instruction unit, changes the bit density in the start area of ​​a shingled recording band and in each area storing information other than user data to be lower than the bit density in areas other than the start area, thereby improving write characteristics.

7. a thermally assisted magnetic recording head including a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on a recording surface facing a thermally assisted magnetic recording head; a track error correction code change instruction unit that instructs a change of the track error correction code in the start area of ​​the shingled recording band and in each area storing information other than user data; and a format control unit that, based on information from a track error correction code change instruction unit, changes the parity number of the track error correction code in the start area of ​​the shingled recording band and in each area storing information other than user data to a parity number higher than the parity number of the track error correction code in areas other than the start area, thereby improving write characteristics.

8. a thermally assisted magnetic recording head including a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on a recording surface facing a thermally assisted magnetic recording head; a laser current or write current change instruction unit that instructs a change in a laser current or a write current in a start area of ​​a shingled recording band and in each area storing information other than user data; and a format control unit that, based on information from a laser current or write current change instruction unit, increases the laser current or write current in the start area of ​​a shingled recording band and in each area storing information other than user data to be higher than the laser current or write current in areas other than the start area, thereby improving write characteristics.

9. a thermally assisted magnetic recording head including a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on a recording surface facing a thermally assisted magnetic recording head; a track density change instruction unit that instructs a change in track density in a start area of ​​a shingled recording band and in each area storing information other than user data; and a servo control unit that, based on information from a track density change instruction unit, reduces the track density in the start area of ​​a shingled recording band and in each area storing information other than user data to be lower than the track density in areas other than the start area, thereby improving write characteristics.

10. a thermally assisted magnetic recording head including a main pole, a near-field light element that generates near-field light, a waveguide that propagates light to the near-field light element, and a light source that supplies light to the waveguide; a thermally assisted magnetic recording medium having a lubricant layer on a recording surface facing a thermally assisted magnetic recording head; a flying height change instruction unit that instructs a change in flying height in a start area of ​​a shingled recording band and in each area storing information other than user data; and a flying height control unit that, based on information from a flying height change instruction unit, reduces the flying height in the start area of ​​a shingled recording band and in each area storing information other than user data to be lower than the flying height in areas other than the start area, thereby improving write characteristics.

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