Magnetic recording apparatus

Abstract

To provide a magnetic recording device capable of improving recording density by suppressing deterioration in recording quality caused by a defect on a recording medium.SOLUTION: According to an embodiment, a magnetic recording device includes a magnetic head including a disk-shaped recording medium, a recording element, a light source, a light emitting element, and a sensor, an inspection circuit configured to detect a height of a defect based on an output of the sensor, a memory configured to record the height of the defect, and a controller including a setting circuit configured to set, on a track of the recording medium having the defect, an upstream recording and reproduction prohibited sector upstream of the defect and a downstream recording and reproduction prohibited sector downstream of the defect with respect to a traveling direction of the magnetic head, the downstream recording and reproduction prohibited sector being longer than the upstream recording and reproduction prohibited sector in a track direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a magnetic recording device. [Background technology]

[0002] One magnetic recording device that has been proposed is one that uses a magnetic head based on the heat-assisted magnetic recording (HAMR) method. HAMR is a technology that increases recording capacity by heating the recording medium with a laser during recording. In HAMR, as the temperature of the recording medium rises, a product made from components present on the recording medium adheres between the light-emitting element of the magnetic head and the recording medium, forming a hardened material (hereinafter referred to as build-up). This hardened material functions as a layer that increases the thermal conductivity of the laser. This makes it possible to increase the temperature of the recording medium without increasing the laser output.

[0003] On the other hand, the recording surface of a recording medium contains defects that arise during the manufacturing process of the recording medium, such as minute scratches, defects due to sputter flakes, and microprotrusions (bumps) with a height of about 1 to 8 nm. Therefore, when a magnetic head runs over the recording surface with a small gap, the built-up cured material may collide with defects such as microprotrusions and be scraped off. Immediately after the cured material is scraped off, the thermal conduction efficiency of the laser may decrease, which may result in a deterioration in magnetic recording quality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,922,676 [Patent Document 2] U.S. Patent No. 7,099,097 [Patent Document 3] U.S. Patent No. 10,614,850 [Patent Document 4] U.S. Patent No. 10,950,267 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the embodiments of the present invention is to provide a magnetic recording device that can suppress degradation of recording quality caused by defects on a recording medium and improve recording density. [Means for solving the problem]

[0006] According to an embodiment, a magnetic recording device comprises a disk-shaped recording medium, a magnetic head including a recording element, a light source, a light-emitting element that irradiates light onto the recording surface of the recording medium, and a sensor that detects defects present on the recording surface of the recording medium, an inspection circuit that detects the height of defects present on the recording surface of the recording medium based on the output of the sensor, a memory that records the height of the detected defects, a setting circuit that sets an upstream write / read prohibited sector upstream of the defect in the running direction of the magnetic head on a track of the recording medium where the defect exists, and sets a downstream write / read prohibited sector downstream of the defect that is longer in the track direction than the upstream write / read prohibited sector, and a controller that includes a light source control circuit that controls the output of the light source. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram schematically showing a hard disk drive (HDD) according to a first embodiment. [Figure 2] FIG. 2 is a side view schematically showing the magnetic head, suspension, and magnetic disk in the HDD. [Figure 3] FIG. 3 is an enlarged cross-sectional view of a head portion of the magnetic head. [Figure 4] FIG. 4 is a diagram schematically showing the head portion of the magnetic head in a state where the write head portion is protruded by a thermal actuator. [Figure 5]FIG. 5 is a diagram showing the output of a thermal resistance sensor when passing over a minute protrusion (bump) on a recording medium. [Figure 6] FIG. 6 is a diagram showing the relationship between bump height and prohibited area. [Figure 7] FIG. 7 is a plan view schematically showing bumps on a recording surface, read / write prohibited tracks, and read / write prohibited sectors. [Figure 8] FIG. 8 is a diagram showing a schematic view of the head portion, the bump, and the read / write prohibited sectors before the bump impact. [Figure 9] FIG. 9 is a diagram showing a schematic view of the head portion, the bump, and the read / write prohibited sector immediately after the bump impact. [Figure 10] FIG. 10 is a diagram showing a head portion, bumps, and read / write prohibited sectors when a hardened material is produced. [Figure 11] FIG. 11 is a plan view schematically showing bumps and read / write prohibited sectors on a recording surface of an HDD according to a second embodiment. [Figure 12] FIG. 12 is a diagram schematically showing a head portion, bumps, and read / write prohibited sectors when the bumps are high in an HDD according to a second embodiment. [Figure 13] FIG. 13 is a diagram schematically showing a head portion, bumps, and read / write prohibited sectors when the bumps are low in an HDD according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A magnetic recording device according to an embodiment will be described below 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 or simplified as appropriate.

[0009] (First embodiment) As an example of a magnetic recording device, a hard disk drive (HDD) according to the first embodiment will be described in detail. Fig. 1 is a block diagram showing a schematic diagram of the HDD according to the first embodiment, and Fig. 2 is a side view showing a magnetic head and a magnetic disk in a floating state. 1, HDD 10 includes a rectangular housing 11, a magnetic disk 12 as a recording medium disposed within housing 11, a spindle motor 14 that supports and rotates magnetic disk 12, and a plurality of magnetic heads 16 that record (write) and reproduce (read) data on magnetic disk 12. HDD 10 includes a head actuator 18 that moves and positions magnetic head 16 over any track on magnetic disk 12. Head actuator 18 includes a carriage assembly 20 that movably supports magnetic head 16, and a voice coil motor (VCM) 22 that rotates carriage assembly 20.

[0010] The HDD 10 is equipped with a controller including a head amplifier IC 30 that drives the magnetic head 16, a main controller 40, and a driver IC 48. The head amplifier IC 30 is provided, for example, in the carriage assembly 20, and is electrically connected to the magnetic head 16. The head amplifier IC 30 includes a recording current supply circuit (recording current supply unit) 30a that supplies a recording current to the recording coil of the magnetic head 16, a heater power supply circuit 30b that supplies drive power to a thermal actuator (heater) of the magnetic head 16, which will be described later, a sensor output amplifier circuit 30c that amplifies a detection signal from the thermal resistance sensor HR, a read signal amplifier circuit 30d that amplifies a signal read by the magnetic head 16, and a light source drive power supply circuit 30e that supplies drive power to a laser oscillator, for example, a laser diode unit (LDU), which will be described later.

[0011] The main controller 40 and driver IC 48 are configured, for example, on a control circuit board (not shown) provided on the rear side of the housing 11. The main controller 40 includes a read / write channel (R / W channel) 42, a hard disk controller (HDC) 44, a microprocessor (MPU) 46, a memory 47, etc. The main controller 40 is electrically connected to the magnetic head 16 via the head amplifier IC 30. The main controller 40 is electrically connected to the VCM 22 and the spindle motor 14 via the driver IC 48. The HDC 44 can be connected to a host computer 45.

[0012] In the main controller 40, the MPU 46 includes a write control unit 46a that controls the write head, a read control unit 46b that controls the read head, a heater control unit 46c that controls the power supplied to the thermal actuator, an inspection circuit 46d, a determination circuit 46e, an area setting circuit 46f that sets a prohibited area, and a light source control unit 46g that controls the driving of the light source. As will be described later, the inspection circuit 46d inspects the presence and size of minute protrusions (bumps) on the surface of the magnetic disk 12 based on the sensor output of the magnetic head 16. A memory 47 stores various data such as the height and width of the bumps, write-prohibited tracks, write-prohibited sectors, and heater power setting values, which are the inspection results.

[0013] As shown in FIGS. 1 and 2, the magnetic disk 12 is configured as a perpendicular magnetic recording medium. The magnetic disk 12 has a substrate 101 made of a non-magnetic material and formed into a disk shape. A heat sink layer 102, a crystalline orientation layer 103, a magnetic recording layer 104 having magnetic anisotropy perpendicular to the surface of the magnetic disk 12, and a protective layer 105 having a lubricant applied thereto are sequentially stacked on the upper and lower surfaces of the substrate 101. The crystalline orientation layer 103 is provided to improve the orientation of the magnetic recording layer 104. The heat sink layer 102 is disposed below the crystalline orientation layer 103 to suppress the expansion of the heated region. The magnetic disk 12 contains a Si-based material, such as SiOx.

[0014] The HDD 10 includes a plurality of, for example, ten, magnetic disks 12. The magnetic disks 12 are coaxially fitted to the hub of a spindle motor 14. The magnetic disks 12 are rotated by the spindle motor 14 in the direction of the arrow at a predetermined speed. 1, a large number of concentric recording tracks T1 to Tn are formed on each surface (magnetic recording layer) of the magnetic disk 12. Each of the recording tracks T1 to Tn includes a plurality of sectors aligned in the circumferential direction.

[0015] The carriage assembly 20 has a bearing 24 rotatably supported on the housing 11, and a plurality of arms and suspensions 26 extending from the bearing 24. As shown in Fig. 2, the magnetic head 16 is supported on the extending ends of the suspensions 26. The magnetic head 16 is electrically connected to a head amplifier IC 30 via a wiring member (flexure) 28 provided on the carriage assembly 20.

[0016] 2, the magnetic head 16 is configured as a floating-type head and includes a slider 15 formed in a substantially rectangular parallelepiped shape and a head portion 17 formed at the end of the slider 15 on the trailing end 15b side. The slider 15 is formed, for example, from a sintered body (AlTiC) of alumina and titanium carbide, and the head portion 17 is formed from multiple thin films. The slider 15 is attached to a gimbal portion 28a of a wiring member 28.

[0017] The slider 15 has a substantially rectangular disk-facing surface (air bearing surface (ABS)) 13 that faces the surface of the magnetic disk 12, and a back surface attached to the gimbal portion 28a. A laser oscillator, such as a laser diode unit (LDU) 25, which functions as a light source, is fixed to the back surface of the slider 15. The slider 15 is maintained in a state where it is lifted a predetermined distance above the surface of the magnetic disk 12 by airflow that occurs between the disk surface and the ABS 13 as the magnetic disk 12 rotates. As the magnetic disk 12 rotates, the magnetic head 16 moves relative to the magnetic disk 12 in the direction of arrow A (head movement direction), i.e., in the direction opposite to the disk rotation direction.

[0018] FIG. 3 is an enlarged cross-sectional view showing the head portion 17 of the magnetic head 16 and the magnetic disk 12. As shown in FIG. As shown in FIG. 3, the head unit 17 has a read head (sometimes referred to as a reproducing element) 54 and a write head (sometimes referred to as a recording element) 58 formed by a thin-film process on the trailing end 15b of the slider 15. The read head 54 and the write head 58 are covered with a nonmagnetic protective insulating film 53, except for the portions exposed to the ABS 13 of the slider 15. The protective insulating film 53 forms the outer shape of the head unit 17. The head unit 17 also has a light-emitting element (here, a near-field light generating element) that irradiates light onto the magnetic disk surface, a waveguide 66 that transmits laser light generated by the LDU 25 to the near-field light generating element 65, a thermal resistance sensor HR that detects the surface condition (defect condition) of the magnetic disk surface, a first thermal actuator that controls the protrusion amount of the write head 58, and a second thermal actuator that controls the protrusion amount of the read head 54. As will be described later, the surface condition of the magnetic disk refers to the presence or absence of defects (microprotrusions or recesses) on the surface of the magnetic disk, and the height and width of the microprotrusions (bumps).

[0019] The longitudinal direction (circumferential direction) of the recording track formed on the magnetic recording layer 104 of the magnetic disk 12 is defined as the track direction DT, and the width direction of the recording track perpendicular to the longitudinal direction is defined as the cross-track direction. The read head 54 has a magnetic film 55 exhibiting a magnetoresistive effect and shielding films 56 and 57 disposed on the trailing and leading sides of the magnetic film 55 so as to sandwich the magnetic film 55. The magnetic film 55 and the shielding films 56 and 57 extend substantially perpendicular to the ABS 13. The lower ends of the magnetic film 55 and the shielding films 56 and 57 are exposed to the ABS 13 of the slider 15.

[0020] The write head 58 is provided on the trailing end 15b side of the slider 15 with respect to the read head 54. The write head 58 has a main pole 60 that generates a recording magnetic field perpendicular to the surface of the magnetic disk 12, a trailing yoke 62 made of a soft magnetic material that is joined to the trailing side of the main pole 60 and that passes magnetic flux to the main pole 60, a return shield pole 64 made of a soft magnetic material that is arranged opposite the leading side of the main pole 60 with a write gap therebetween, a joint 67 that physically joins the top of the trailing yoke 62 to the return shield pole 64, and a write coil 70 that is arranged to be wound around a magnetic path that includes the trailing yoke 62 and the return shield pole 64 in order to pass magnetic flux to the main pole 60. The tip surface of the main pole 60 , the tip surface of the trailing yoke 62 , the tip of the near-field light generating element 65 , and the tip surface of the return shield pole 64 are exposed to the ABS 13 of the slider 15 .

[0021] The main pole 60 is made of a soft magnetic material with high magnetic permeability and high saturation magnetic flux density, and extends substantially perpendicular to the ABS 13. The main pole 60 has a tip surface exposed to the ABS 43 and a magnetic pole end surface that extends upward from the ABS 13, i.e., in a direction away from the ABS 13, and faces the near-field light generating element 65.

[0022] The near-field light generating element (plasmon generator, near-field transducer) 65 is provided between the main magnetic pole 60 and the return shield magnetic pole 64, and faces parallel to the magnetic pole end face of the main magnetic pole 60 with a gap (gap length) between them. The end of the near-field light generating element 65 on the ABS 13 side is formed parallel to and flush with the ABS 13. The near-field light generating element 65 is preferably made of Au, Pd, Pt, Rh, or Ir, or an alloy made of a combination of some of these. An insulating layer is interposed between the main pole 60 and the near-field light generating element 65, and this insulating layer is preferably an oxide made of SiO2, Al2O3, or the like.

[0023] The waveguide 66 extends from the ABS 13 to the back surface of the slider 42, i.e., the end surface on the suspension side, and is optically connected to the LDU 25. The end (extending end) of the waveguide 66 on the ABS 13 side faces the near-field light generating element 65 substantially in parallel with a gap therebetween. An insulating layer is interposed between the waveguide 66 and the near-field light generating element 65.

[0024] The first thermal actuator has a heating element, for example, heater 76a. Heater 76a is embedded in the protective insulating film 53 and is located near the write head 58. The second thermal actuator has a heating element, for example, heater 76b. Heater 76b is embedded in the protective insulating film 53 and is located near the read head 54.

[0025] The thermal resistance sensor HR is embedded in the protective insulating film 53 and is located between the write head 58 and the read head 54. The detection end (tip) of the thermal resistance sensor HR is exposed to the ABS 13 or protrudes slightly from the ABS 13. The thermal resistance sensor HR is used as an example of an HDI (head-disk interface) sensor.

[0026] The recording coil 70 is connected to the head amplifier IC 30 via wiring (not shown) and the flexure 28. When writing a signal to the magnetic disk 12, a recording current is supplied from the recording current supply circuit 30a of the head amplifier IC 30 to the recording coil 70, thereby exciting the main pole 60 and causing magnetic flux to flow through the main pole 60. The recording current supplied to the recording coil 70 is controlled by the write control unit 46a of the main controller 40. The read head 54 is connected to the head amplifier IC 30 via wiring (not shown) and the flexure 28. The signal read by the read head 54 is amplified by a read signal amplifier circuit 30d of the head amplifier IC 30 and sent to the main controller 40.

[0027] The first heater 76a and the second heater 76b are connected to the head amplifier IC 30 via wiring and the flexure 28, respectively. By applying drive power to the first heater 76a and the second heater 76b from the heater power supply circuit 30b of the head amplifier IC 30, the heater and the area around the heater are heated, causing the write head 58 or the read head 54 to bulge toward the magnetic disk 12. In other words, by adjusting the amount of bulging, the flying height of the magnetic head 16 can be adjusted. The heater power supplied to the first heater 76a and the second heater 76b is controlled by the heater control unit 46c of the main controller 40.

[0028] The thermal resistance sensor HR is connected to the head amplifier IC 30 via wiring and the flexure 28. The detection signal (sensor output) of the thermal resistance sensor HR is amplified by the sensor output amplifier circuit 30c of the head amplifier IC 30 and sent to the inspection circuit 46d of the main controller 40.

[0029] The LDU 25 is connected to the head amplifier IC 30 via wiring (not shown) and a flexure 28. When drive power is applied to the LDU 25 from the light source drive power supply circuit 30e of the head amplifier IC 30, the LDU 25 oscillates a laser beam. The laser beam is input to a waveguide 66 and supplied to the near-field light generating element 65 through the waveguide 66. The drive power supplied to the LDU 25 is controlled by a light source control unit 46g of the main controller 40.

[0030] As shown in Fig. 1, in the HDD 10 configured as described above, by driving the VCM 16, the head actuator 18 rotates, and the magnetic head 16 is moved and positioned above a desired track on the magnetic disk 12. As shown in Fig. 2, when the HDD 10 is in operation, the magnetic head 16 faces the disk surface with a gap maintained. The magnetic head 16 floats in an inclined position with the write head 58 portion of the head unit 17 closest to the surface of the magnetic disk 12. In this state, the read head 54 reads recorded information from the magnetic disk 12, and the write head 58 writes information (signals) to the magnetic disk 12.

[0031] FIG. 4 is a cross-sectional view that schematically shows the head portion 17 of the magnetic head 16 and a part of the magnetic disk 12 during a write operation. 4, during a write operation of the magnetic head 16, drive power is applied to the first heater 76a, which heats the first heater 76a and its surroundings, causing the write head 58 to bulge out toward the magnetic disk 12. As a result, the gap (head flying height) d1 between the write head 58 and the surface of the magnetic disk 12 is set to about 1 nm.

[0032] When writing information, the main pole 60 is excited by the recording coil 70, and a perpendicular recording magnetic field is applied from the main pole 60 to the magnetic recording layer 104 of the magnetic disk 12 directly below, thereby recording information at a desired track width. In thermally assisted magnetic recording, when writing information, laser light is supplied from the LDU 25 through the waveguide 66 to the near-field light generating element 65, which generates near-field light. The near-field light generated from the tip of the near-field light generating element 65 locally heats the magnetic recording layer 104 of the magnetic disk 12, thereby reducing the coercivity of the recording area. A recording magnetic field from the main pole 60 is applied to this reduced coercivity area to write a signal. In this way, high-density recording is possible by locally heating the magnetic recording layer 104 and writing a signal in an area where the coercivity has been sufficiently reduced.

[0033] On the other hand, when the magnetic head 16 travels over the protective layer 105 at a flying height d1, a lubricant fills the gap between the lubricant layer 106 applied to the protective layer 105 and the tip of the near-field light generating element 65. In this state, when near-field light is irradiated onto the magnetic recording layer 104 and the lubricant layer 106 applied to the protective layer 105, the magnetic recording layer 104 and the lubricant are locally heated, and a hardened lubricant is produced. By irradiating near-field light for a predetermined time, a hardened lubricant is produced in the lubricant filled between the tip of the near-field light generating element 65 and the lubricant layer 106, and a hardened lubricant HM having a height d1 adheres to the tip of the near-field light generating element 65. The main component of the cured material HM is SiOx, which is generated from the environment and the magnetic recording layer. When the cured material HM is formed, the transmission efficiency of near-field light improves, making it possible to efficiently heat the magnetic recording layer 104. In other words, it becomes possible to reduce the laser output of the LDU 25.

[0034] The amount of cured material HM produced depends on the siloxanes contained in the environment and the Si atoms contained in the magnetic disk 12. The greater the Si content, the larger the cured material HM produced. In the HDD 10 according to this embodiment, the main controller 40 monitors the time until the cured material HM is produced and measures the correlation between the production time and the height of the cured material HM produced. The measurement results are registered in the memory 47 as production time data.

[0035] As mentioned above, if there are defects such as minute protrusions (bumps) on the recording surface of the magnetic disk 12, the hardened material HM adhering to the magnetic head 16 may collide with the defects and be scraped off. Immediately after being scraped off, the thermal conductivity decreases, resulting in a drop in recording quality. Therefore, the HDD 10 of this embodiment is configured to set a recording / reproduction prohibited track or a recording / reproduction prohibited sector on the magnetic recording layer 104 according to the height of the bump, and to set a hardened material formation area in part of the recording / reproduction prohibited sector, the area having a length equivalent to the generation time required to generate the hardened material, so that the hardened material can be immediately filled in.

[0036] This section describes the operation of detecting small protrusions (bumps) on the surface of the magnetic disk 12 and setting write-prohibited tracks or write-prohibited sectors in the HDD 10 according to this embodiment. The HDD 10 performs bump detection and write-prohibited track and write-prohibited sector setting, for example, after manufacture, before shipping, or periodically.

[0037] FIG. 5 is a diagram showing a schematic diagram of the output of the thermal resistance sensor when it comes into contact with a minute protrusion on a recording medium. As shown in Figure 5, if a protrusion (bump) B higher than the flying height d1 of the thermal resistance sensor HR occurs on the surface of the magnetic disk 12, the thermal resistance sensor HR will collide with the protrusion as it passes over the bump B, causing a change in the resistance value of the thermal resistance sensor HR, i.e., a decrease in the resistance value. As a result, the output waveform of the thermal resistance sensor HR will have a lowered portion corresponding to the contact area R1. From the output waveform, the width of the contact area R1 with the protrusion B, i.e., the width of the protrusion B, can be determined. The height of the bump B can also be calculated based on the flying height d1 of the magnetic head 16 when the thermal resistance sensor HR collides with the protrusion. As shown in FIG. 5, in this embodiment, the height of the protrusion (bump) B is the height in the direction perpendicular to the surface of the magnetic disk 12, and the width of the protrusion (bump) is the width in the track direction.

[0038] In the bump detection operation, the controller 40 scans all tracks T1 to Tn of the magnetic disk 12 with the magnetic head 16 while sequentially changing the flying height of the magnetic head 16. In one example, if the flying height of the magnetic head 16 during normal recording is set to a specified value (e.g., 1 nm), bumps are detected by scanning all tracks T1 to Tn with a flying height smaller than the specified value, e.g., 0.7 nm. Next, bumps are detected by scanning all tracks T1 to Tn with the flying height of the magnetic head 16 set to 1 nm. Subsequently, bumps are detected by scanning all tracks T1 to Tn while increasing the flying height of the magnetic head 16 by 0.3 nm each time. Finally, when a flying height at which no fluctuations in the output of the thermal resistance sensor HR occur is reached, i.e., when a flying height at which bumps are not detected is reached, the detection operation of the magnetic head surface is terminated.

[0039] As shown in FIG. 1, the sensor output of the thermal resistance sensor HR is amplified by the head amplifier IC 30 and then sent to the inspection circuit 46d of the main controller 40. Based on the sensor output of the thermal resistance sensor HR, the inspection circuit 46d calculates the position (track, sector), width, and height of bumps present on the surface of the magnetic disk 12. The main controller 40 stores and registers the calculated bump data in the memory 47. In one example, the memory 47 stores a data table indicating the position, height, and width of bumps on each track.

[0040] FIG. 6 is a diagram showing the relationship between the frequency of bump occurrence, bump height, and read / write prohibited areas. As shown in the figure, the recording surface of the magnetic disk 12 contains many bumps that are lower than the detection limit of the thermal resistance sensor HR. In this embodiment, the main controller 40 sets the read / write prohibited areas on a track-by-track basis for bumps higher than a reference height H2 (approximately 5 to 6 nm, for example) that could potentially damage the magnetic head. For bumps higher than the detection limit but lower than the reference height H2, the main controller 40 sets the read / write prohibited areas on a sector-by-sector basis. Setting the read / write prohibited areas on a track-by-track basis results in a corresponding loss of recording capacity. Therefore, the main controller 40 determines whether to set the read / write prohibited areas on a track-by-track or sector-by-sector basis based on the bump height. In FIG. 6, BO (backoff) = 1 indicates that the gap (head flying height) between the write head 58 and the surface of the magnetic disk 12 when the first heater 76a causes the write head 58 to bulge toward the magnetic disk 12 is 1 nm.

[0041] FIG. 7 is a plan view showing a schematic diagram of bumps on the recording surface, recording / reproduction prohibited tracks, and recording / reproduction prohibited sectors. The determination circuit 46e of the MPU 46 determines the height of the bump B on each of the tracks T1 to Tn based on the bump data registered in the memory 47, and determines whether to set a recording / reproduction prohibited area on a track-by-track basis or a recording / reproduction prohibited area on a sector-by-sector basis depending on the height of the bump B. Based on the determination result of the determination circuit 46e, the area setting circuit 46f of the MPU 46 sets the number of recording / reproduction prohibited tracks Tp corresponding to the height of the bump B, or sets the number of recording / reproduction prohibited sectors Sp corresponding to the height of the bump B, and registers them in the memory 47.

[0042] 7, for a bump B2 that has been determined to be a bump for setting a recording / reproducing prohibited area on a track-by-track basis, the area setting circuit 46f sets three tracks including the bump B2 as recording / reproducing prohibited tracks Tp and registers them in the memory 47. A total of three recording / reproducing prohibited tracks Tp are set, one on the inner periphery and one on the outer periphery, with the track on which the bump B2 is located at the center.

[0043] For a bump B1 that is determined to be a bump for setting a recording / reproducing prohibited area on a sector-by-sector basis, the area setting circuit 46f sets recording / reproducing prohibited sectors Sp on the upstream and downstream sides of the bump B1 for six tracks including the bump B1, and registers them in the memory 47. Specifically, write / read inhibit sectors St are set on six tracks, three on the inner and three on the outer periphery, centered on the track and sector where bump B1 is present. An upstream write / read inhibit sector SpU is set one sector upstream of bump B1 in the magnetic head running direction A. A downstream write / read inhibit sector SpD is set downstream of bump B1.

[0044] The downstream recording / playback prohibited sector SpD is longer in the track direction than the upstream recording / playback prohibited sector SpU, i.e., it includes more sectors. The downstream recording / playback prohibited sector SpD includes a recording / playback prohibited area SpD1 of one sector downstream of the bump B1. Furthermore, the downstream recording / playback prohibited sector SpD includes a hardened material formation area (hardened material formation sector) SpD2 of multiple sectors, for example, five sectors, continuing downstream from the recording / playback prohibited area SpD1.

[0045] The number of sectors set in the upstream recording / reproducing prohibited sectors SpU and the downstream recording / reproducing prohibited area SpD1 is not limited to the above example, and can be increased as necessary. The number of recording / reproducing prohibited sectors can be determined according to the height of the bump B1, and the higher the bump height, the greater the number of recording / reproducing prohibited sectors. In this embodiment, the six tracks of hardened material formation regions SpD2 are set to a common length (five sectors). The length (number of sectors) of the hardened material formation regions SpD2 can be increased or decreased depending on the height of the bumps B1 and the generation time data of the hardened material HM registered in the memory 47. That is, the higher the bumps B1, the more hardened material is scraped off, so the hardened material formation regions SpD2 are set to be longer.

[0046] When the HDD 10 is in operation, the main controller 40 performs a data recording operation on the recording tracks T other than the recording / reproducing prohibited tracks Tp registered in the memory 47. After the setting, the main controller 40 prohibits recording / reproducing operations on the recording / reproducing prohibited tracks Tp, that is, prohibits the magnetic head 16 from accessing the recording / reproducing prohibited tracks Tp. The main controller 40 executes the following data recording operation on the recording track where the recording / reproducing prohibited sector St is set.

[0047] 8, 9 and 10 are diagrams showing the write operation of the magnetic head and the hardened material forming operation when passing through the read / write prohibited sector St. 8, before the magnetic head 16 collides with the bump B1, the main controller 40 supplies a recording current to the magnetic head 16 and turns on the LDU 25 to irradiate the recording layer of the magnetic disk 12 with near-field light until the magnetic head 16 reaches the start position SS of the upstream recording / reproducing prohibited sector SpU. At this time, the magnetic head 16 is assumed to be floating a predetermined floating amount d1, for example, about 1 nm, and a hardened material HM is formed between the light emitting element 65 of the magnetic head and the recording surface of the magnetic disk 12.

[0048] When the magnetic head 16 reaches the upstream end of the upstream recording / playback prohibited sector SpU, i.e., the recording / playback prohibited start position SS, the main controller 40 stops the write operation and turns off the power supply of the LDU 25, i.e., stops emitting near-field light.

[0049] 9, when the magnetic head 16 passes over the bump B1, the cured material HM adhering to the light-emitting element collides with the bump B1, causing a portion of the cured material HM to be scraped off, resulting in a cured material with a reduced height.

[0050] 10, when the magnetic head 16 reaches the end of the downstream recording / reproduction prohibited area SpD1, i.e., the start position BS of the cured product formation area SpD2, the main controller 40 turns on the power of the LDU 25, causing the light-emitting element to irradiate near-field light onto the recording surface of the magnetic disk 12. The main controller 40 keeps the LDU 25 on until the magnetic head 16 reaches the recording / reproduction prohibited end position SE, which is the end of the cured product formation area SpD2. As a result, a cured product HM is gradually formed at the tip of the light-emitting element, and by the time the magnetic head 16 reaches the recording / reproduction prohibited end position SE, a cured product HM has been produced that has grown to a height approximately equal to the flying height d1 of the magnetic head 16.

[0051] After the magnetic head 16 reaches the recording / reproducing prohibition end position SE, the main controller 40 supplies a recording current to the magnetic head 16 to start a write operation. At the same time, the main controller 40 turns on the LDU 25 and drives it at a predetermined output, thereby irradiating the recording layer of the magnetic disk 12 with near-field light. At this point, a sufficient amount of hardened material HM has adhered to the tip of the light-emitting element, improving the transmission efficiency of the near-field light and enabling the magnetic recording layer 104 of the magnetic disk 12 to be heated efficiently.

[0052] As mentioned above, the length (number of sectors) of the hardened material formation area SpD2 in the recording / playback prohibited sector Sp is set based on the height of the bump B1 (the amount of hardened material scraped off by the bump B1) and the generation time data registered in memory 47, and is set to a length that will allow the hardened material HM scraped off by the bump B1 to be generated up to a predetermined height d1. The output of the LDU 25 during cured product formation, i.e., while passing through the cured product formation region SpD2, can be set as desired. The output of the LDU 25 during cured product formation may be the same as or different from the output of the LDU 25 during write operation. If the output of the LDU 25 during cured product formation is set higher than the output during normal write operation, the time required to generate a cured product can be shortened, but damage to the magnetic disk 12 and the LDU 25 will increase accordingly. Therefore, it is desirable to adjust the output of the LDU 25 taking into account the balance between generation time and damage. The light source control unit 46g may be provided with a user-selectable output switch or the like.

[0053] The HDD according to the first embodiment, configured as described above, provides read / write prohibited areas upstream and downstream of the bumps on the recording surface, and further provides a hardened material formation area in the downstream read / write prohibited area. This allows for the hardened material to be immediately formed as the magnetic head passes through the hardened material formation area, even if the hardened material is scraped off by passing over the bumps, and a sufficient amount of hardened material can be filled at the tip of the light-emitting element of the magnetic head. Therefore, the magnetic recording layer of the magnetic disk can be heated with high thermal conductivity immediately after passing over the bumps. As described above, according to the first embodiment, it is possible to obtain a magnetic recording device that can suppress degradation of recording quality caused by defects on the recording medium and improve recording density.

[0054] Next, an HDD according to another embodiment will be described. In the following description of the other embodiment, the same parts as those in the first embodiment will be assigned the same reference numerals, and detailed descriptions thereof will be omitted or simplified. The following description will focus on parts that are different from the first embodiment.

[0055] (Second embodiment) FIG. 11 is a plan view schematically showing bumps and read / write prohibited sectors on a recording surface in an HDD according to the second embodiment. When the cured material HM adhering to the light-emitting element collides with a bump, the degree to which the cured material is scraped off depends on the height of the bump. Therefore, according to the second embodiment, the height of the bumps occurring on the recording surface of the magnetic disk is inspected and registered, and the length (number of sectors) of the cured material formation area SpD2 in the read / write prohibited sector St is determined according to the height of each bump. Even for the same bump, the degree of wear varies depending on the location where the magnetic head passes. In other words, the height of the same bump may differ depending on the location.

[0056] 11, according to the second embodiment, in the recording / reproducing prohibited sector St, the length (number of sectors) of the hardened material formation region SpD2 is changed depending on the height of the bump B. In the example shown, the bump B is tall at the center and short at both ends in the track width direction. Therefore, for the recording track passing through the center of the bump B, the hardened material formation region SpD2 is set long, for example, five sectors, and for the recording track passing through both ends of the bump B, the hardened material formation region SpD2 is set short, for example, four or three sectors.

[0057] Fig. 12 is a diagram showing a typical write operation of the magnetic head and a typical hardened material forming operation when passing through the write / read prohibition sector St located at the center of the bump B. Fig. 13 is a diagram showing a typical write operation of the magnetic head and a typical hardened material forming operation when passing through the write / read prohibition sector St located at the end of the bump B. 12, when the magnetic head passes through the center of the bump B, i.e., the high part, the hardened material HM of the magnetic head collides with the bump B and most of it is scraped off. Even in this case, since the hardened material formation region SpD2 is set long, the hardened material is sufficiently filled while passing through the hardened material formation region SpD2, and a hardened material of the predetermined height is generated.

[0058] 13, when passing over the end of the bump B, i.e., a low-height portion, the amount of the cured material HM scraped off is relatively small, and about half of the cured material HM is maintained. Therefore, even if the cured material formation region SpD2 is set short, the cured material can be formed to a predetermined height while passing over the cured material formation region SpD2.

[0059] The HDD according to the second embodiment configured as described above can achieve the same effect as the HDD according to the first embodiment. That is, the HDD according to the second embodiment can achieve a magnetic recording device that can suppress degradation of recording quality due to defects on the recording medium and improve recording density. Furthermore, according to the second embodiment, by setting the length of the hardened material formation region according to the height of the bump, for example, by setting the length of the hardened material formation region to be shorter for a bump with a low height, it is possible to increase the sectors of the recording region and increase the recording capacity.

[0060] In the second embodiment, the bump and the length of the hardened material formation region are not limited to the example shown in Fig. 11, and can be changed in various ways depending on the shape of the bump. For example, there are various types of bumps, such as bumps that are high at one end and decrease toward the other end, or bumps that are high at both ends and decrease in the center, and the length of the hardened material formation region may be set to be long or short depending on the height of each part of the bump.

[0061] 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 embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments are included within the scope and spirit of the invention, as well as within the scope of the inventions described in the claims and their equivalents. For example, the number of recording / reproducing prohibited sectors and the number of sectors in the hardened material formation area, which are set according to the height of the bumps, are not limited to the above-described embodiment and can be increased or decreased as necessary. The above-described embodiment can also be applied to HDDs using a shingled recording method. The materials, shapes, sizes, etc. of the elements that make up the head portion of the magnetic head can be changed as needed. The number of magnetic disks and the number of magnetic heads in the magnetic recording device can be increased or decreased as needed. Various sizes of magnetic disks can be selected. [Explanation of symbols]

[0062] 10...magnetic disk device, 11...casing, 12...magnetic disk, 15...slider, 16...magnetic head, 17...head unit, 18...head actuator, 25...LDU, 30...Head amplifier IC, 40...Main controller, 46d...inspection circuit, 46e...determination circuit, 54...read head, 58...write head, 65... near-field optical element (light-emitting element), 66... ​​waveguide, 76a... first heater, 76b...second heater, HR...thermal resistance sensor, HM...hardened material, T1 to Tn...recording track, Tp: Recording / playback prohibited track, St: Recording / playback prohibited sector, SpU: Upstream write / read prohibited sector, SpD: Downstream write / read prohibited sector, SpD1: downstream recording / reproducing prohibited area, SpD2: hardened material forming area, B, B1, B2...Bump

Claims

1. a disk-shaped recording medium; a magnetic head including a recording element, a light source, a light emitting element that irradiates light onto a recording surface of the recording medium, and a sensor that detects defects present on the recording surface of the recording medium; a controller including an inspection circuit that detects the height of a defect present on the recording surface of the recording medium based on the output of the sensor; a memory that records the height of the detected defect; a setting circuit that sets an upstream write / read inhibit sector upstream of the defect in the track of the recording medium in the running direction of the magnetic head and sets a downstream write / read inhibit sector downstream of the defect, the downstream write / read inhibit sector having a length in the track direction longer than the upstream write / read inhibit sector; and a light source control circuit that controls the output of the light source; A magnetic recording device comprising:

2. 2. The magnetic recording device according to claim 1, wherein the downstream recording / reproducing prohibited sector includes a recording / reproducing prohibited area continuing downstream of the defect, and a hardened material formation area extending from the recording / reproducing prohibited area to the end of the downstream recording / reproducing prohibited sector.

3. the controller includes a write control unit that inhibits a write operation of the recording element in the upstream write / read prohibited sector and the downstream write / read prohibited sector; 3. The magnetic recording device according to claim 2, wherein the light source control circuit stops output of the light source in the upstream write / read prohibited sector and the downstream write / read prohibited area, and outputs light from the light source in the hardened product formation area.

4. 3. The magnetic recording device according to claim 2, wherein the setting circuit sets the length of the hardened material formation region in the track direction in accordance with the height of the defect.

5. 2. The magnetic recording device according to claim 1, wherein the setting circuit sets a plurality of recording / reproducing prohibited tracks for defects on the recording surface of the recording medium that are higher than a reference height, and sets the upstream recording / reproducing prohibited sectors and the downstream recording / reproducing prohibited sectors for defects that are lower than the reference height.

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