Magnetic disk device

Abstract

An embodiment of the present invention provides a magnetic disk device capable of appropriately setting a data region of a magnetic disk while taking into account a change in amplitude of off-track vibration with respect to a change in ambient temperature. A magnetic disk device according to an embodiment includes a magnetic disk and a magnetic head. The disk has a data region in which data can be recorded and reproduced. The magnetic head records data in the data area and reproduces data from the data area. The outer edge of the data region includes a first outer edge, a second outer edge positioned further toward the inner peripheral side of the magnetic disk than the first outer edge, and a third outer edge connecting the first outer edge and the second outer edge, and at least a portion of the outer edge has a recess recessed toward the inner peripheral side of the magnetic disk.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2023-216591 (filing date: December 22, 2023). This application incorporates the entire contents of the base application by reference thereto. Technical Field

[0002] The embodiment relates to a disk device. Background Art

[0003] On the surface of a disk as a recording medium for a disk device, there are irregularities generated during its manufacturing process. When the slider of a magnetic head passes over such an irregularity portion, the slider is likely to undergo off-track vibration. Off-track vibration is vibration in the off-track direction, which causes a positioning error of the magnetic head with respect to the track of the disk. The off-track direction is a direction parallel to the surface of the disk and perpendicular to the track of the disk, which is directly the radial direction of the disk. The amplitude of off-track vibration varies according to the temperature (ambient temperature) in the environment where the disk device is used, and thus may be larger than expected. In a state where the amplitude of off-track vibration is large, there is a possibility of interfering with the adjacent track of the track to be written and writing data. Therefore, in such a case where the amplitude of off-track vibration becomes large, it is necessary to set the target track as a prohibited recording (unreadable data).

[0004] Therefore, in order to improve the recording density and reliability of the disk device, it is necessary to set a region (hereinafter referred to as a data region) on the disk that can be used for recording and reproducing data, taking into account the change in the amplitude of off-track vibration with respect to the ambient temperature change. Summary of the Invention

[0005] Embodiments of the present invention provide a disk device that can appropriately set a data region of a disk while taking into account the change in the amplitude of off-track vibration with respect to the ambient temperature change.

[0006] The disk device according to the embodiment includes a disk and a magnetic head. The disk has a data region where data can be recorded and reproduced. The magnetic head records the data in the data region and reproduces the data from the data region. The outer edge of the data region has a first outer edge, a second outer edge located on the inner circumferential side of the disk compared to the first outer edge, and a third outer edge connecting between the first outer edge and the second outer edge, and at least a part thereof has a concave portion recessed toward the inner circumferential side of the disk. Brief Description of the Drawings

[0007] Figure 1 It is a block diagram showing a schematic configuration of a disk device (HDD) according to an embodiment.

[0008] Figure 2It is a diagram schematically showing a disk according to an embodiment and a head floating above the disk from the side thereof.

[0009] Figure 3 It is a plan view for explaining a film-forming process of forming a film on the surface of a substrate of a disk of a disk device (HDD) according to an embodiment.

[0010] Figure 4 It is a diagram showing a comparison of a head floating guarantee area and the degree of floating of the head outside the area in a disk device (HDD) according to an embodiment.

[0011] Figure 5 It is a diagram showing the shift (change in film thickness) of a film formed on a substrate of a disk having a holding member influence portion in a disk device (HDD) according to an embodiment.

[0012] Figure 6 It is a plan view for explaining the form of shear force generated between a slider of a head and a disk surface in a disk according to an embodiment.

[0013] Figure 7 It is a diagram showing the form of off-track vibration generated in a slider of a head in a disk device (HDD) according to an embodiment.

[0014] Figure 8 It is a diagram for explaining the relationship between temperature and off-track vibration in a test machine of a disk device (HDD) according to an embodiment.

[0015] Figure 9 It is a diagram showing the relationship between the radius position of a disk and off-track vibration in a disk device (HDD) according to an embodiment.

[0016] Figure 10 It is a plan view showing the form of a data area of a disk in a disk device (HDD) according to the present embodiment.

[0017] Figure 11 It is a diagram schematically showing an example of whether data recording and reproduction are permitted for each sector in each track of a plurality of tracks of a disk in a disk device (HDD) according to the present embodiment.

[0018] Description of Reference Numerals

[0019] 10…Disk device (HDD), 12…Disk, 15…Slider, 16…Magnetic head, 17…Head, 18…Head actuator, 20…Carriage assembly, 22…Voice coil motor (VCM), 24…Bearing portion, 26…Arm (suspension), 28…Wiring member (flexible), 30…Head amplifier IC, 40…Main controller, 42…R / W channel, 44…Hard disk controller (HDC), 45…Host, 46…Microprocessor (MPU), 46a…Write control section, 46b…Read control section, 46c…Data area management section, 47…Memory, 48…Driver IC, 80, 81, 82, 83…Holder influence portion, 81a, 82a, 83a…Extension of holder influence portion, 101…Substrate, 101a…Outer peripheral surface, 102…Soft magnetic layer, 103…Perpendicular magnetic recording layer, 104…Protective film, 110…Data area, 110a…Outer edge of data area, 111…Recess, 121…First outer edge, 122…Second outer edge, 123…Third outer edge, C32…Innermost circumference of floating guarantee area, C32…Innermost circumference of floating guarantee area, X91…Innermost radius position of floating guarantee area (innermost circumference of floating guarantee area), X92…Outermost radius position of floating guarantee area (outermost circumference of floating guarantee area), X93…Disk outer edge portion (outer edge position of disk (outer peripheral surface position of substrate)), Y81…Allowable off-track vibration amplitude, Y82…Allowable off-track vibration amplitude threshold, Y8A, Y9…Allowable off-track vibration amplitude reference value. Detailed implementation mode

[0020] Hereinafter, with reference to Figures 1 to 11 , the disk device according to the embodiment will be described.

[0021] Figure 1 is a block diagram showing a schematic configuration of a hard disk drive (hereinafter referred to as HDD) 10 according to the embodiment. The HDD 10 is an example of a disk device.

[0022] As Figure 1 shown, the HDD 10 includes: a rectangular housing 11; a disk 12 as a recording medium housed in the housing 11; a spindle motor 14 that supports and rotates the disk 12; and a magnetic head 16 that records (writes) and reproduces (reads) data on the disk 12 (specifically, a data area 110 described later). The number of the disk 12 and the magnetic head 16 is not limited to one, and may be plural. The housing 11 has, for example, a rectangular box-shaped base (not shown) with an upper opening, and a lid (not shown) covering the opening of the base.

[0023] The HDD 10 includes a head actuator 18 that moves the head 16 to a desired track on the disk 12 and positions it. The head actuator 18 includes a carriage assembly 20 that supports the head 16 in a movable manner, and a voice coil motor (hereinafter referred to as VCM) 22 that rotates the carriage assembly 20.

[0024] The HDD 10 includes a controller that includes a head amplifier IC 30 that drives the head 16, a main controller 40, and a driver IC 48. The head amplifier IC 30 is provided, for example, on the carriage assembly 20 and is electrically connected to the head 16. The head amplifier IC 30 includes a write driver and a read amplifier. The write driver outputs a recording (write) current corresponding to a signal output from the R / W channel 42 to the head 16. The read amplifier amplifies a reproduction (read) signal read from the disk 12 and outputs it to the main controller 40 (specifically, the R / W channel 42 described later).

[0025] The main controller 40 and the driver IC 48 are configured, for example, as control circuit boards (not shown) provided on the back side of the housing 11. The main controller 40 includes an R / W channel 42, a hard disk controller (hereinafter referred to as HDC) 44, a microprocessor (hereinafter referred to as MPU) 46, a memory 47, and the like. The main controller 40 is electrically connected to the 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 the host 45.

[0026] Data area information is stored in the memory 47 of the main controller 40. A data area is an area on the disk 12 where predetermined data is recorded and reproduced. The data area 110 includes a user data area that can be used by the user and a system data area required for system management. Hereinafter, the circumferential direction of the disk 12 will be referred to as the track direction, and the radial direction of the disk 12, that is, the direction parallel to the disk 12 and orthogonal to the track direction will be referred to as the skew direction.

[0027] The data area information is information related to the data area 110 of the disk 12, and is, for example, a set of information including information on a holding member influence portion existing on the surface of the disk 12 described later, information indicating the outer edge position of the data area 110 of the disk 12, information indicating whether data recording and reproduction are permitted for the sectors of the disk 12, and the like. This information is obtained, for example, in the quality inspection of the disk 12 before the product (HDD 10) is shipped. Details of the data area information and its acquisition, management, etc. will be described later.

[0028] In the main controller 40, for example, the MPU 46 includes: a write control unit 46a that controls the writing of a recording (write) head, a read control unit 46b that controls the reproduction (read) of a reproduction (read) head, and a data area management unit 46c that manages the data area. The MPU 46 executes the processing of the write control unit 46a, the read control unit 46b, and the data area management unit 46c on firmware, for example. In addition, the MPU 60 may also include the write control unit 46a, the read control unit 46b, and the data area management unit 46c as circuits.

[0029] According to a command from the host 45, the write control unit 46a controls the recording (write) process of recording (writing) data to the disk 12, and the read control unit 46b controls the reproduction (read) process of reproducing (reading) data from the disk 12. The write control unit 46a and the read control unit 46b control the VCM 22 via the drive IC 48 to position (seek) the head (recording head and reproduction head) 16 to a target position on the disk 12.

[0030] The data area management unit 46c manages the data area 110 of the disk 12. In the present embodiment, as will be described later, the data area management unit 46c performs an LBA allocation process on the data area 110 based on the recording / reproduction permission table.

[0031] Figure 2 It is a diagram schematically showing the disk 12 and the head 16 floating relative to the disk 12 from the side.

[0032] As Figure 1 and Figure 2 shown, the disk 12 is configured as a perpendicular magnetic recording medium. The disk 12 has, for example, a substrate 101 formed of a non-magnetic material in a disk shape with a diameter of 96 mm (about 3.5 inches).

[0033] On each surface of the substrate 101, a soft magnetic layer 102 as a base layer formed of a material having soft magnetic properties, a perpendicular magnetic recording layer 103 having magnetic anisotropy in the perpendicular direction with respect to the surface of the disk 12, and a protective film 104 are laminated in this order from the lower layer to the upper layer. The data area 110 of the disk 12 is configured to include the soft magnetic layer 102, the perpendicular magnetic recording layer 103, and the protective film 104 laminated on the surface of the substrate 101.

[0034] In addition, the data area 110 of the disk 12 may be provided only on one side of the substrate 101. A plurality of disks 12 are coaxially fitted into the hub of the spindle motor 14. These disks 12 are rotated by the spindle motor 14 at a predetermined speed in a predetermined direction (the direction indicated by the arrow B).

[0035] The carriage assembly 20 has a bearing portion 24 rotatably supported by the housing 11 and a plurality of arms (suspensions) 26 extending from the bearing portion 24. As Figure 2 shown, the magnetic head 16 is supported at the extending ends of the respective arms 26. The magnetic head 16 is electrically connected to the head amplifier IC 30 via a wiring member (flexible member) 28 provided in the carriage assembly 20.

[0036] As Figure 2 shown, the magnetic head 16 is configured as a flying head, having a slider 15 formed in a substantially rectangular parallelepiped shape and a head 17 formed on the slider 15. The slider 15 is formed of, for example, a sintered body of alumina and titanium carbide (AlTiC), and the head 17 is formed of a multilayer thin film. The slider 15 is mounted on the gimbal portion 28a of the wiring member 28.

[0037] The slider 15 has a substantially rectangular disk facing surface (air bearing surface (hereinafter referred to as ABS)) 13 facing the surface of the disk 12. The slider 15 is maintained in a state of floating a predetermined amount from the surface of the disk 12 by an air flow C generated between the disk surface and the ABS 13 due to the rotation of the disk 12. The direction of the air flow C (the direction indicated by the arrow C) is the same as the rotation direction B of the disk 12. The slider 15 has a leading end 15a on the inflow side of the air flow C and a trailing end 15b on the outflow side of the air flow C. The head 17 is formed at the trailing end 15b of the slider 15. As the disk 12 rotates, the magnetic head 16 moves relative to the disk 12 in the direction indicated by the arrow A (head movement direction), that is, in the direction opposite to the rotation direction B of the disk 12.

[0038] Next, the management of the data area information of the disk 12 in the present embodiment will be described. As a premise, first, the general characteristics of the disk 12 will be described.

[0039] Figure 3 is a plan view for explaining a film forming process of forming a soft magnetic layer 102, a perpendicular magnetic recording layer 103, and a protective film 104 on the surface of the annular substrate 101 of the disk 12. The data area 110 of the disk 12 is configured to include a soft magnetic layer 102, a perpendicular magnetic recording layer 103, and a protective film 104 laminated on the surface of the substrate 101.

[0040] As Figure 3 shown, in the disk 12, the data area 110 is provided at a position inside the outermost peripheral radius position of the floating guarantee area of the magnetic head 16 (hereinafter referred to as the outermost periphery of the floating guarantee area). The floating guarantee area of the magnetic head 16 is an area where the magnetic head 16 can physically float from the disk surface of the disk 12 to record and reproduce data in the data area 110.

[0041] In Figure 3In the example shown, the area between the dashed line C31 and the dashed line C32 is the floating guarantee area. The dashed line C31 represents the outermost periphery of the floating guarantee area, and the dashed line C32 represents the innermost periphery of the floating guarantee area (the innermost peripheral radius position of the floating guarantee area). In order to efficiently increase the recording capacity of the HDD 10, it is only necessary to make the outermost periphery C31 of the floating guarantee area as close as possible to the outer edge portion of the disk 12 and to increase the data area 110 as much as possible.

[0042] Figure 4 is a diagram that compares and shows the floating degree of the magnetic head in the floating guarantee area of the magnetic head and outside this area. In Figure 4 , the horizontal axis represents the distance (floating gap) between the disk surface of the disk and the magnetic head (for example, the ABS of the slider), and the vertical axis represents the output value of the AE (Acoustic Emission) sensor. The AE sensor is a contact sensor provided in the slider of the magnetic head of the HDD test machine, and detects the contact between the disk surface and the magnetic head. The stronger the contact between the two, the higher the detection output. Therefore, based on the detection output of the AE sensor, it is possible to determine to what extent the slider of the magnetic head can float relative to the disk surface. That is, if it is known at what floating gap the slider of the magnetic head performs recording and reproduction relative to the disk, the floating guarantee area of the magnetic head can be determined.

[0043] In Figure 4 , the thick line L41 represents the trajectory of the floating state of the magnetic head in the floating guarantee area, and the thin line L42 represents the trajectory of the floating state of the magnetic head outside the floating guarantee area. As shown by the thin line L42 in Figure 4 , outside the floating guarantee area, when the gap between the disk surface and the magnetic head becomes narrower than X42, the detection output of the AE sensor rises sharply. In contrast, as shown by the thick line L41 in Figure 4 , in the floating guarantee area, when the gap between the disk surface and the magnetic head becomes narrower than X41 which is smaller than X42, the detection output of the AE sensor rises sharply. Y4 is the allowable value of the detection output of the AE sensor from the viewpoint of the floating guarantee of the magnetic head, and in the illustrated example, it corresponds to the detection output value of the AE sensor at the gaps X41 and X42.

[0044] In this way, in the illustrated example, the value of the gap X4A which is smaller than the gap X42 and larger than the gap X41 is set as the floating guarantee value of such a magnetic head. In other words, if the detection output of the AE sensor rises sharply at the gap X4A which is the floating guarantee value, it can be presumed, for example, that the area of the disk surface closer to the inside than the position of the magnetic head at this time is within the floating guarantee area.

[0045] As in Figure 2 and Figure 3As shown, the disk 12 is formed by applying a multi-layer film (three layers in the illustrated example) to the surface of the substrate 101. In order to appropriately maintain the posture of the substrate 101 during film formation, it is necessary to hold the substrate 101. In Figure 3 In the illustrated film formation process example, the substrate 101 is held by the holding member 90. The holding member 90 abuts against the outer peripheral surface 101a of the substrate 101 and presses the outer peripheral surface 101a in the off-track direction. The number of holding members 90 for holding the substrate 101 is not particularly limited. In the illustrated example, the posture of the substrate 101 is held by three holding members 91, 92, and 93.

[0046] When the substrate 101 is held by the holding member 90, the film thickness at the portion held by the holding member 90 during film formation of the substrate 101 is different from the film thickness at the portion not held. That is, in the disk 12, a portion (hereinafter referred to as the holding member influence portion) 80 where the thickness (film thickness) of the film (for example, the perpendicular magnetic recording layer 103) formed at the portion where the substrate 101 is held by the holding member 90 is different from the film thickness at the portion not held is present. Therefore, the thickness of the film formed on the substrate 101 is not uniform but uneven.

[0047] In the illustrated example, with respect to the disk 12, there is one holding member influence portion in each of the portions held by the three holding members 91, 92, and 93, and there are three holding member influence portions 81, 82, and 83. These holding member influence portions 81, 82, and 83 extend in the off-track direction from the outer peripheral surface 101a pressed by the holding members 91, 92, and 93. The holding member influence portions 81, 82, and 83 in the illustrated example are in a triangular shape whose width gradually narrows as it faces the inside in the off-track direction (the center of the disk 12). However, the planar shape of the holding member influence portions 81, 82, and 83 is not limited to such a triangular shape. In addition, for convenience, the planar shapes of the holding member influence portions 81, 82, and 83 are illustrated as the same, but their actual planar shapes are not the same.

[0048] Figure 5 It is a diagram showing the displacement (change in film thickness) of the film formed on the substrate 101 of the disk 12 in the track where the holding member influence portions 81, 82, and 83 are present. In Figure 5 In it, the horizontal axis represents the circumferential position, and the vertical axis represents the displacement of the film. The displacement of the film here is expressed as: the degree of change in film thickness when the film thickness at the portion where the holding member influence portions 81, 82, and 83 are not present (hereinafter referred to as the normal region) is set to 0. In Figure 5In the example shown, at the circumferential positions P81, P82, and P83 corresponding to the holding member influence portions 81, 82, and 83, the film thickness changes sharply with respect to the normal region. As the displacement of the film, a case where the film thickness decreases sharply (becomes thin) is envisioned, that is, a case where the holding member influence portions 81, 82, and 83 are concave portions with respect to the normal region. However, there is also a case where the film thickness increases sharply (becomes thick), that is, a case where the holding member influence portions 81, 82, and 83 are convex portions with respect to the normal region.

[0049] Thus, at the holding member influence portion 80, the film is displaced (the film thickness changes) with respect to the normal region. That is, at the holding member influence portion 80 and the normal region, the gap between the disk surface of the disk 12 and the head 16 changes. However, there is the following situation: When performing a test for the head floating guarantee as described with reference to Figure 4 the detection output of the AE sensor does not rise at the holding member influence portion 80 and becomes below the allowable value. In this case, it will be erroneously determined that the holding member influence portion 80 is a normal region. In other words, it will be erroneously determined that the holding member influence portion 80 is included in the appropriate floating guarantee region.

[0050] On the other hand, when the slider 15 of the head 16 passes over the disk surface of the rotating disk 12, a shear force acts between the slider 15 and the disk surface. Figure 6 It is a plan view for explaining the form of the shear force generated between the slider 15 and the disk surface.

[0051] As Figure 6 shown by the double-dot dash line, for example, when the slider 15 of the head 16 is located at an inner circumferential position of the disk 12, the center line of the arm 26 of the carriage assembly 20 becomes a state along the circumferential direction (rotation direction B) of the disk 12. At this time, between the slider 15 passing over the disk surface of the rotating disk 12 and the disk surface, a shear force acts in the direction along the center line of the arm 26. The center line of the arm 26 is an imaginary line connecting the rotation center C20 of the bearing portion 24 of the carriage assembly 20 and the center C15 of the slider 15 ( Figure 6 the single-dot dash line L6 shown).

[0052] In contrast, as Figure 6 shown by the solid line, for example, when the slider 15 of the head 16 is located at an outer circumferential position of the disk 12, at the position of the slider 15 passing over the disk surface of the rotating disk 12, the center line L6 of the arm 26 becomes a state inclined at a predetermined angle with respect to the circumferential direction (rotation direction B) of the disk 12. At this time, between the slider 15 passing over the disk surface of the rotating disk 12 and the disk surface, a shear force acts as Figure 6 shown by the arrow F6 of the solid line in

[0053] This shearing force F6 has a component in the direction crossing the tracks of the disk 12 with respect to the arm 26 ( Figure 6 the component shown by the dashed arrow F61 in

[0054] Figure 7 . Hereinafter, it is referred to as the component force F61). Due to the action of this component force F61, the arm 26 of the carriage assembly 20, directly speaking, the slider 15 of the head 16 vibrates in the off-track direction. Hereinafter, this vibration is referred to as off-track vibration. When the slider 15 passes over the holder influence portion 80, the gap between the head 16 and the disk surface changes, and thus the shearing force acting between them changes. Therefore, when the slider 15 passes over the holder influence portion 80, the amplitude of the off-track vibration also changes. Figure 7 is a diagram showing the form of the off-track vibration generated in the slider 15 of the head 16. In Figure 5 , the form of the off-track vibration of the slider 15 corresponding to the displacement of the film of the substrate 101 (change in film thickness) is shown. Here, the form of the off-track vibration in the tracks of the disk 12 where there are

[0055] as shown in Figure 7 is shown. Corresponding to the sharp change in the film thickness with respect to the normal region at the circumferential positions P81, P82, P83, the slider 15 undergoes off-track vibration. That is, in the regions S92, S94, S96 which are the normal regions outside the circumferential positions P81, P82, P83 corresponding to the holder influence portions 81, 82, 83, almost no off-track vibration occurs. In contrast, in the ranges S91, S93, S95 of the circumferential positions P81, P82, P83 corresponding to the holder influence portions 81, 82, 83, off-track vibration occurs. In other words, at the holder influence portions 81, 82, 83, the amplitude of the off-track vibration is larger than that in the normal region. In the illustrated example, the amplitude of the off-track vibration in the normal regions (S92, S94, S96) is almost zero.

[0056] As long as the amplitude of the off-track vibration is within an allowable range, the generation of this off-track vibration itself is not a particularly big problem. The off-track vibration, directly speaking, the maximum amplitude of the off-track vibration depends on the temperature. This is because the damping material (vibration damping material) of the support body carrying the slider 15 of the head 16 has temperature characteristics. The temperature here is the ambient temperature of the HDD 10. Generally speaking, when the ambient temperature becomes low, the damping performance deteriorates, and thus the amplitude of the off-track vibration becomes larger.

[0057] Figure 8 is a diagram showing the relationship between the temperature and the off-track vibration in the test machine of the HDD 10. In Figure 8In the figure, the horizontal axis represents the temperature (ambient temperature), and the vertical axis represents the maximum amplitude of the off-track vibration. In this testing machine, there is a holding member influence portion 80 in the disk 12. In Figure 8 it shows the temperature characteristics of the maximum amplitude of the off-track vibration generated in the slider 15 of the magnetic head 16 in such a testing machine of the HDD 10. Here, as an example, it shows: when the magnetic head 16 records and reproduces data on a predetermined track of the disk 12 of the testing machine of the HDD 10, the temperature characteristics of the maximum amplitude of the off-track vibration generated in the slider 15 of the magnetic head 16. In Figure 8 it, the solid lines L81, L82, and L83 are the trajectories corresponding to the respective results in the case where the temperature characteristics of the maximum amplitude of the off-track vibration generated in the slider 15 of the magnetic head 16 are measured three times.

[0058] In Figure 8 it, X8H is the maximum operating temperature of the HDD 10, and X8L is the minimum operating temperature of the HDD 10. The maximum operating temperature X8H is the maximum temperature of the ambient temperature assumed for the operation of the HDD 10, and as an example, it is about 60°C (hereinafter referred to as high temperature). The minimum operating temperature X8L is the minimum temperature of the ambient temperature assumed for the operation of the HDD 10, and as an example, it is about 5°C (hereinafter referred to as low temperature). In contrast, X8A is the execution temperature of the measurement test of the maximum amplitude of the off-track vibration (hereinafter referred to as the measurement temperature X8A), that is, the ambient temperature of the HDD 10 set during the test, and here it is normal temperature (about 30°C). This test is executed when setting the outer edge position of the data area 110 in the HDD 10 described later.

[0059] In Figure 8 the temperature characteristics shown by the solid line L81 and the temperature characteristics shown by the solid line L82, the maximum amplitude of the off-track vibration is lower than the value of the allowable value (hereinafter referred to as the allowable off-track vibration amplitude) Y81 at the maximum operating temperature X8H and the measurement temperature X8A, that is, at high temperature and normal temperature. However, the maximum amplitude of the off-track vibration exceeds the value of the allowable off-track vibration amplitude Y81 at the minimum operating temperature X8L, that is, at low temperature. That is, at a temperature lower than the measurement temperature X8A and higher than the minimum operating temperature X8L, the maximum amplitude of the off-track vibration exceeds the value of the allowable off-track vibration amplitude Y81.

[0060] In contrast, Figure 8 in the temperature characteristics shown by the solid line L83, the maximum amplitude of the off-track vibration is lower than the value of the allowable off-track vibration amplitude Y81 at the maximum operating temperature X8H and the measurement temperature X8A, that is, at high temperature and normal temperature. Moreover, the maximum amplitude of the off-track vibration is also lower than the value of the allowable off-track vibration amplitude Y81 at the minimum operating temperature X8L, that is, at low temperature. That is, in any of the cases of high temperature, normal temperature, and low temperature, the maximum amplitude of the off-track vibration is limited within the range of the allowable off-track vibration amplitude Y81.

[0061] Therefore, when the maximum amplitude of the off-track vibration at the measurement temperature X8A, i.e., room temperature, is equal to or less than the value of the temperature characteristic shown by the solid line L83 (hereinafter referred to as the allowable off-track vibration amplitude threshold) Y82, based on the temperature characteristic shown by the solid line L83, it can be presumed that the maximum amplitude of the off-track vibration at the lowest operating temperature X8L, i.e., low temperature, can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81.

[0062] In addition, in this case, when the maximum amplitude of the off-track vibration at the measurement temperature X8A, i.e., room temperature, is equal to or less than a predetermined threshold Y8A, it can be more reliably presumed that the maximum amplitude of the off-track vibration at the lowest operating temperature X8L, i.e., low temperature, can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81. The predetermined threshold Y8A is a predetermined value that is smaller than the value of the allowable off-track vibration amplitude Y81 and larger than the allowable off-track vibration amplitude threshold Y82, and as an example, it is the allowable off-track vibration amplitude reference value Y9 described later.

[0063] Here, as Figure 3 and Figure 6 shown, the holder influence portion 80 extends from the outer peripheral surface 101a of the substrate 101 of the disk 12 toward the inner side in the off-track direction. Therefore, regarding the off-track vibration generated in the slider 15 of the magnetic head 16 when passing over the holder influence portion 80, the smaller the region is toward the inner side in the off-track direction. That is, the smaller the influence of the holder influence portion 80 on the off-track vibration is in the region toward the inner side in the off-track direction.

[0064] Therefore, in the present embodiment, the slider 15 is moved to the radius position where the maximum amplitude of the off-track vibration becomes equal to or less than the allowable off-track vibration amplitude Y81 for testing, and the evaluation is repeated. Thus, the radius position of the disk 12 where the maximum amplitude of the off-track vibration of the slider 15 becomes the allowable off-track vibration amplitude Y81 can be set.

[0065] Figure 9 is a diagram showing the relationship between the radius position of the disk 12 in the HDD 10 and the off-track vibration. In Figure 9 it, the horizontal axis represents the radius position of the disk 12, i.e., the distance from the rotation center of the disk 12, and the vertical axis represents the maximum amplitude of the off-track vibration. X91 represents the innermost radius position (innermost periphery of the floating guarantee area) of the floating guarantee area where the magnetic head 16 records and reproduces data on the disk 12, and X92 represents the outermost radius position (outermost periphery of the floating guarantee area) of the floating guarantee area. In addition, X93 represents the outer edge position of the disk 12 (the position of the outer peripheral surface 101a of the substrate 101) (hereinafter, also referred to as the disk outer edge portion X93).

[0066] As Figure 9As shown, in the HDD 10, the maximum amplitude of the off-track vibration slightly increases from the innermost circumference X91 of the floating guarantee area, but remains almost constant, and changes to a sharp increase near the outermost circumference X92 of the floating guarantee area. Also, the maximum amplitude of the off-track vibration exceeds a predetermined threshold value at the outermost circumference X92 of the floating guarantee area and further increases until the outer edge position (disk outer edge part) X93. The predetermined threshold value at this time is the allowable off-track vibration amplitude reference value Y9.

[0067] The allowable off-track vibration amplitude reference value Y9 is set based on Figure 8 the allowable off-track vibration amplitude Y81 shown. For example, it is set to a value smaller than the value of the allowable off-track vibration amplitude Y81. As an example, it is set to a predetermined value that is smaller than the value of the allowable off-track vibration amplitude Y81 and larger than the allowable off-track vibration amplitude threshold Y82 ( Figure 8 the predetermined threshold value Y8A shown).

[0068] According to such a setting, when the maximum amplitude of the off-track vibration at the measurement temperature X8A, i.e., normal temperature, is below the allowable off-track vibration amplitude reference value Y9, according to Figure 8 the example shown, it can be more reliably presumed that the maximum amplitude of the off-track vibration at the lowest operating temperature X8L, i.e., low temperature, can be suppressed below the allowable off-track vibration amplitude Y81.

[0069] Therefore, in Figure 9 the value X9A of the radius position of the disk 12 when the maximum amplitude of the off-track vibration becomes the allowable off-track vibration amplitude reference value Y9 is set as the outer edge position of the data area 110. Thus, at the radius position X9A of the data area 110, the maximum amplitude of the off-track vibration of the slider 15 of the head 16 can be reliably suppressed below the allowable off-track vibration amplitude Y81.

[0070] In Figure 9 the example shown, the cause of the off-track vibration is the holder influence part 80. Therefore, for the area of the disk 12 other than the holder influence part 80, the off-track vibration caused by the holder influence part 80 is suppressed to the minimum, directly speaking, its maximum amplitude is suppressed below the allowable off-track vibration amplitude Y81. Therefore, the area of the disk 12 in the data area 110 other than the holder influence part 80 is extended to the outermost circumference X92 of the floating guarantee area. In other words, the area of the data area 110 corresponding to the holder influence part 80 is narrowed inward compared to the outermost circumference X92 of the floating guarantee area.

[0071] Figure 10It is a plan view showing the form of the data area 110 of the disk 12 in the HDD 10 according to this embodiment. In the illustrated example, there are three holder influence portions 81, 82, and 83 in the disk 12. These three holder influence portions 81, 82, and 83 extend from the disk outer edge portion X93 toward the inner side in the off-track direction, exceeding the outermost periphery X92 of the floating guarantee area. That is, the three holder influence portions 81, 82, and 83 have portions (hereinafter referred to as extension portions) 81a, 82a, and 83a located at positions inside the outermost periphery X92 of the floating guarantee area.

[0072] As Figure 10 shown, the outer edge 110a of the data area 110 of the disk 12 bypasses (avoids) the extension portions 81a, 82a, and 83a of the holder influence portions 81, 82, and 83 and enters the inner side in the off-track direction. The portion of the outer edge 110a of the data area 110 corresponding to other than the extension portions 81a, 82a, and 83a (hereinafter referred to as the first outer edge) 121 is set to Figure 9 the outermost peripheral radius position (outermost periphery of the floating guarantee area) of the floating guarantee area shown by X92 in the figure. The first outer edge 121 is continuous in an arc shape concentric with the disk 12. In contrast, the portion of the outer edge 110a of the data area 110 corresponding to the extension portions 81a, 82a, and 83a (hereinafter referred to as the second outer edge) 122 is located on the inner peripheral side of the disk 12 compared to the first outer edge 121. The second outer edge 122 is set to Figure 9 the radius position shown by X9A in the figure. The portion connecting the first outer edge 121 and the second outer edge 122 (hereinafter referred to as the third outer edge) 123 corresponds to the boundary between the sectors where the holder influence portions 81, 82, and 83 exist and the sectors where the holder influence portions 81, 82, and 83 do not exist, which will be described later. That is, the outer edge 110a of the data area 110 has the first outer edge 121, the second outer edge 122, and the third outer edge 123.

[0073] As a result, the data area 110 has the following form: The portion corresponding directly to the extension portions 81a, 82a, and 83a, that is, the portion corresponding to the holder influence portions 81, 82, and 83, is narrowed in a substantially rectangular concave shape compared to the first outer edge 121 (outermost periphery X92 of the floating guarantee area). That is, the data area 110 has the following form: The portion corresponding to other than the extension portions 81a, 82a, and 83a, that is, the portion corresponding directly to other than the holder influence portions 81, 82, and 83, extends from the second outer edge 122 to the first outer edge 121. In other words, through the first outer edge 121, the second outer edge 122, and the third outer edge 123, a concave portion 111 is defined in the outer edge 110a of the data area 110. That is, at least a part (three places in the illustrated example) of the outer edge 110a of the data area 110 has a concave portion 111 recessed toward the inner peripheral side of the disk 12.

[0074] In the data area 110, in the recess 111 which corresponds to the holding member influencing portions 81, 82, 83 and is narrower than the first outer edge 121 (the outermost periphery X92 of the floating guarantee area), recording and reproduction of data are prohibited. That is, the recess 111 is excluded from the data area 110. Whether to allow or prohibit (allowance or not) recording and reproduction of data is set for each sector of the track where the holding member influencing portions 81, 82, 83 exist.

[0075] As described above, in the magnetic disk 12, the film thickness of the holding member influencing portions 81, 82, 83 (for example, the thickness of the perpendicular magnetic recording layer 103) is different from the film thickness of the other portions. The recess 111 is arranged corresponding to the holding member influencing portions 81, 82, 83 and is excluded from the data area 110. Therefore, the film thickness of the perpendicular magnetic recording layer 103 of the recess 111 is different from the film thickness of the perpendicular magnetic recording layer 103 of the data area 110.

[0076] Figure 11 It is a diagram schematically showing an example of whether recording and reproduction of data are allowed for each sector in each track of a plurality of tracks of the magnetic disk 12. Data can be recorded and reproduced for sectors where recording and reproduction of data are allowed, and data cannot be recorded and reproduced for sectors where recording and reproduction of data are prohibited. The magnetic disk 12 in the illustrated example has m + 1 tracks assigned track numbers from 0 to m. Regarding the track numbers, the track existing at the outermost periphery X92 of the floating guarantee area is set to 0, and they are assigned in ascending order from this track toward the inner side in the skew direction, and the track existing at the innermost periphery X91 of the floating guarantee area is set to m. Each of these tracks has n + 1 sectors assigned sector numbers from 0 to n. m and n are arbitrary natural numbers and can be different or the same.

[0077] In the illustrated example, holding member influencing portions 80 exist in sector 4 and sector 5 of track 0, and sector 4 and sector 5 of track 1. Therefore, recording and reproduction of data are prohibited for these four sectors. In Figure 11 these, these prohibited sectors are represented by a grid. In contrast, sectors other than sector 4 and 5 of track 0 and sectors other than sector 4 and 5 of track 1 allow recording and reproduction of data. In addition, all sectors 1 to n of each track from track 2 to track m allow recording and reproduction of data. That is, all sectors of all tracks located on the inner side in the skew direction compared with track 1 allow recording and reproduction of data. In Figure 11 these, these allowed sectors are represented by a blank.

[0078] Whether data recording and reproduction in each sector of such multiple tracks is permitted is managed, for example, by a table (hereinafter referred to as the recording and reproduction permission table) in which values of a predetermined flag (hereinafter referred to as the recording and reproduction flag) are set. As an example, a value of 0 is set for the recording and reproduction flag in a sector where data recording and reproduction is permitted, and a value of 1 is set for the recording and reproduction flag in a sector where data recording and reproduction is prohibited, enabling the two to be uniquely distinguished. Further, the values of these recording and reproduction flags are recorded for each sector of all tracks of all disks 12 of the HDD 10 in the recording and reproduction permission table and tabulated.

[0079] The recording and reproduction permission table is created, for example, by the data area management unit 46c of the MPU 46 during quality inspection (testing) before the product (HDD 10) is shipped and stored as data area information in the non-volatile memory of the memory 47 of the host controller 40. Further, the data area management unit 46c performs a process of allocating logical addresses to the sectors of the disk 12 (hereinafter referred to as the LBA allocation process). The LBA allocation process is a process of allocating logical addresses to the disk 12 based on the recording and reproduction permission table, that is, based on the presence or absence of the holder influence unit 80 of the disk 12. In the LBA allocation process, the data area management unit 46c appropriately allocates logical addresses to the sectors according to the values of the recording and reproduction flags of the sectors recorded in the recording and reproduction permission table.

[0080] For example, logical addresses are allocated to sectors where the value of the recording and reproduction flag is set to 0 and data recording and reproduction is permitted. In contrast, logical addresses are not allocated to sectors where the value of the recording and reproduction flag is set to 1 and data recording and reproduction is prohibited. As a result, sectors without the holder influence unit 80 are allocated logical addresses and used as the data area 110 of the disk 12. In contrast, sectors with the holder influence unit 80 are not allocated logical addresses and are excluded from the data area 110 of the disk 12.

[0081] Thus, according to the HDD 10 according to the present embodiment, even when the holder influence unit 80 exists in the disk 12, the off-track vibration of the slider 15 of the head 16 caused by the holder influence unit 80 can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81. At this time, based on Figure 8 the temperature characteristics of the maximum amplitude of the off-track vibration shown, the maximum amplitude of the off-track vibration at a low temperature (around 5°C) can be appropriately estimated in a situation where the ambient temperature of the HDD 10 is normal temperature (around 30°C).

[0082] Therefore, for example, when the HDD 10 is shipped from the factory, the temperature characteristics of the maximum amplitude of the off-track vibration are confirmed at normal temperature (around 30°C) and high temperature (around 60°C). Even if the temperature characteristics at low temperature (around 5°C) are not confirmed from the perspective of manufacturing efficiency, the maximum amplitude of the off-track vibration at low temperature can be appropriately estimated, and the off-track vibration can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81.

[0083] In addition, according to Figure 9 the relationship between the radius position of the disk 12 in the HDD 10 and the off-track vibration as shown, the outer edge 110a of the data area 110 can be set based on the temperature characteristics of the maximum amplitude of the off-track vibration.

[0084] This outer edge 110a is set according to the off-track vibration caused by the holder influence portion 80 of the disk 12. Therefore, the data area 110 corresponding to the holder influence portion 80 can be set to be inside (the second outer edge 122) of the outermost periphery X92 of the floating guarantee area. On the other hand, the data area 110 other than the holder influence portion 80 can be extended to the outermost periphery X92 (the first outer edge 121) of the floating guarantee area. Thus, even if there is a holder influence portion 80 in the disk 12, the data area 110 where data recording and reproduction can be performed can be extended to the maximum extent.

[0085] Therefore, according to the present embodiment, even at low temperature, the maximum amplitude of the off-track vibration can be appropriately suppressed within the range of the allowable off-track vibration amplitude Y81, and the data area 110 can be extended to the maximum extent. As a result, the data area 110 can be set taking into account the amplitude change of the off-track vibration with respect to the ambient temperature change of the HDD 10, and the recording density and reliability of the HDD 10 can be improved.

[0086] The embodiments of the present invention have been described above, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention described in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: a magnetic disk having a data area capable of recording and reproducing data; and a magnetic head for recording the data in the data area and reproducing the data from the data area, The outer edge of the data area includes a first outer edge, a second outer edge, and a third outer edge, and at least a portion thereof has a recessed portion recessed toward the inner circumference of the disk, the second outer edge being located on the inner circumference of the disk compared to the first outer edge, and the third outer edge connecting the first outer edge and the second outer edge.

2. The magnetic disk device according to claim 1, The magnetic disk includes a substrate and a magnetic recording layer provided on a surface of the substrate. The film thickness of the magnetic recording layer in the concave portion is different from the film thickness of the magnetic recording layer in the data region.

3. The magnetic disk device according to claim 2, The recessed portion is arranged in a circumferential direction of the magnetic disk so as to correspond to a position where the substrate is held by a holder when the magnetic recording layer is formed.

4. The magnetic disk device according to claim 3, The first outer edge and the second outer edge are set at the following radial position of the magnetic disk, which is a radial position at which the maximum amplitude of the radial off-track vibration of the magnetic head toward the magnetic disk when recording or reproducing the data on the magnetic disk becomes below a predetermined threshold.

5. The magnetic disk device according to claim 4, The first outer edge is set at the outermost radial position of a region where the magnetic head can float relative to the surface of the magnetic disk.

6. The magnetic disk device according to claim 5, Regarding the maximum amplitude of the off-track vibration of the magnetic head, an allowable value at a predetermined low temperature lower than the normal temperature is estimated based on a detected value when the ambient temperature of the magnetic disk device is at the normal temperature.

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