Magnetic disc device

Abstract

To provide a magnetic disc device capable of appropriately setting a data region of a magnetic disc in view of an amplitude change of off-track vibration for an ambient temperature change.SOLUTION: A magnetic disc device includes a magnetic disc and a magnetic head. The magnetic disc has a data region capable of data recording and playback. The magnetic head records data into a data region and plays back the data from the data region. An outer edge of the data region has: a first outer edge; a second outer edge that is located on an inner circumferential side of the magnetic disc from the first outer edge; and a third outer edge that connects together the first outer edge and the second outer edge, and at least partially has a concaved part that is concaved towards the inner circumferential side of the magnetic disc.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] Embodiments relate to a magnetic disk drive.

Background Art

[0002] On the surface of a magnetic disk, which is a recording medium used in a magnetic disk drive, there are irregularities generated during the manufacturing process. When a slider of a magnetic head passes through such an irregular portion, off-track vibration is likely to occur in the slider. 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 magnetic disk. The off-track direction is parallel to the surface of the magnetic disk and perpendicular to the track of the magnetic disk, and is, simply put, the radial direction of the magnetic disk. Since the amplitude of the off-track vibration changes according to the temperature (ambient temperature) in the environment where the magnetic disk drive is used, it may become larger than expected. In a state where the amplitude of the off-track vibration is large, there is a risk that data is written due to interference with an adjacent track to the track to be written. Therefore, when the amplitude of the off-track vibration becomes large, it is necessary to prohibit recording (data writing is not possible) on the target track.

[0003] Therefore, in order to improve the recording density and reliability of the magnetic disk drive, it is necessary to set a region (hereinafter referred to as a data region) that can be used for data recording and reproduction on the magnetic disk in consideration of the change in the amplitude of the off-track vibration with respect to the change in the ambient temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] An embodiment of the present invention aims to provide a magnetic disk device capable of appropriately setting a data area of a magnetic disk in consideration of a change in the amplitude of off-track vibration with respect to a change in the ambient temperature.

Means for Solving the Problems

[0006] A magnetic disk device according to an embodiment includes a magnetic disk and a magnetic head. The magnetic disk has a data area capable of recording and reproducing data. The magnetic head records the data in the data area and reproduces the data from the data area. The outer edge of the data area has a first outer edge, a second outer edge located on the inner circumferential side of the magnetic disk with respect to the first outer edge, and a third outer edge connecting between the first outer edge and the second outer edge, and has a recess recessed at least partially toward the inner circumferential side of the magnetic disk.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0008] Hereinafter, the magnetic disk device according to the embodiment will be described with reference to FIGS. 1 to 11. FIG. 1 is a block diagram showing a schematic configuration of a hard disk drive (hereinafter referred to as HDD) 10 according to the embodiment. HDD 10 is an example of a magnetic disk device.

[0009] As shown in FIG. 1, the HDD 10 includes a rectangular housing 11, a magnetic disk 12 as a recording medium housed in the housing 11, a spindle motor 14 that supports and rotates the magnetic disk 12, and a magnetic head 16 that records (writes) and reproduces (reads) data with respect to the magnetic disk 12 (specifically, a data area 110 described later). The number of the magnetic disks 12 and the magnetic heads 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 open top and a cover (not shown) covering the opening of the base.

[0010] The HDD 10 includes a head actuator 18 that moves and positions the magnetic head 16 on a desired track of the magnetic disk 12. The head actuator 18 includes a carriage assembly 20 that movably supports the magnetic head 16 and a voice coil motor (hereinafter referred to as VCM) 22 that rotates the carriage assembly 20.

[0011] The HDD 10 includes a controller including a head amp IC 30 that drives the magnetic head 16, a main controller 40, and a driver IC 48. The head amp IC 30 is provided, for example, in the carriage assembly 20 and is electrically connected to the magnetic head 16. The head amp 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 magnetic head 16. The read amplifier amplifies a reproduction (read) signal read from the magnetic disk 12 and outputs it to the main controller 40 (specifically, the R / W channel 42 described later).

[0012] The main controller 40 and the driver IC 48 are configured on a control circuit board (not shown) provided on the back side of the housing 11, for example. 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 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 the host 45.

[0013] Data area information is stored in the memory 47 of the main controller 40. The data area is an area where predetermined data is recorded and reproduced on the magnetic disk 12. The data area 110 includes a user data area available to the user and a system data area necessary for system management. Hereinafter, the circumferential direction of the magnetic disk 12 is referred to as the track direction, and the radial direction of the magnetic disk 12, that is, the direction parallel to the magnetic disk 12 and orthogonal to the track direction is referred to as the off-track direction.

[0014] The data area information is information regarding the data area 110 of the magnetic disk 12, and is a set of information including, for example, information on the holder influence portion existing on the surface of the magnetic disk 12 described later, information indicating the outer edge position of the data area 110 of the magnetic disk 12, and information indicating whether to permit recording and reproduction of data for each sector of the magnetic disk 12. These information are obtained, for example, in the quality inspection of the magnetic disk 12 before the shipment of the product (HDD 10). Details regarding the data area information, its acquisition and management will be described later.

[0015] In the main controller 40, for example, the MPU 46 includes a write control unit 46a that controls the recording (write) head, a read control unit 46b that controls the playback (read) head, and a data area management unit 46c that manages the data area. The MPU 46 executes the processing of, for example, the write control unit 46a, the read control unit 46b, and the data area management unit 46c on the firmware. Note that the MPU 60 may include these write control unit 46a, read control unit 46b, and data area management unit 46c as circuits.

[0016] In accordance with a command from the host 45, the write control unit 46a controls the recording (write) process of data to the magnetic disk 12, and the read control unit 46b controls the playback (read) process of data from the magnetic disk 12. The write control unit 46a and the read control unit 46b control the VCM 22 via the driver IC 48 to position (seek) the magnetic head (recording head and playback head) 16 at a target position on the magnetic disk 12.

[0017] The data area management unit 46c manages the data area 110 of the magnetic disk 12. In the present embodiment, the data area management unit 46c performs LBA allocation processing on the data area 110 based on a recording / playback permission table as described later.

[0018] FIG. 2 is a diagram schematically showing the magnetic disk 12 and the magnetic head 16 floating above the magnetic disk 12 from the sides thereof. As shown in FIGS. 1 and 2, the magnetic disk 12 is configured as a perpendicular magnetic recording medium. The magnetic disk 12 has, for example, a substrate 101 made of a non-magnetic material formed in a disk shape with a diameter of 96 mm (about 3.5 inches).

[0019] On each surface of the substrate 101, a soft magnetic layer 102, which is an underlayer made of a material exhibiting soft magnetic properties, a perpendicular magnetic recording layer 103 having magnetic anisotropy in a direction perpendicular to the surface of the magnetic 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 magnetic disk 12 is configured to include these soft magnetic layer 102, perpendicular magnetic recording layer 103, and protective film 104 laminated on the surface of the substrate 101.

[0020] Note that the data area 110 of the magnetic disk 12 may be provided on only one side of the substrate 101. A plurality of magnetic disks 12 are coaxially fitted to the hub of the spindle motor 14. These magnetic disks 12 rotate at a predetermined speed in a predetermined direction (the direction indicated by arrow B) by the spindle motor 14.

[0021] 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 shown in FIG. 2, the magnetic head 16 is supported at the extending end of each arm 26. The magnetic head 16 is electrically connected to the head amplifier IC 30 via a wiring member (flexure) 28 provided in the carriage assembly 20.

[0022] As shown in FIG. 2, the magnetic head 16 is configured as a flying head and has a slider 15 formed in a substantially rectangular parallelepiped shape and a head portion 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 portion 17 is formed of a plurality of layers of thin films. The slider 15 is attached to the gimbal portion 28a of the wiring member 28.

[0023] The slider 15 has a substantially rectangular disk facing surface (air bearing surface (hereinafter referred to as ABS)) 13 facing the surface of the magnetic disk 12. The slider 15 is maintained in a state of floating by a predetermined amount from the surface of the magnetic disk 12 by an air flow C generated between the disk surface and the ABS 13 due to the rotation of the magnetic disk 12. The direction of the air flow C (the direction indicated by the arrow C) coincides with the rotation direction B of the magnetic disk 12. The slider 15 has a leading end 15a located on the inflow side of the air flow C and a trailing end 15b located on the outflow side of the air flow C. The head portion 17 is formed at the trailing end 15b of the slider 15. As the magnetic disk 12 rotates, the magnetic head 16 travels in the direction indicated by the arrow A (head traveling direction) with respect to the magnetic disk 12, that is, in the direction opposite to the rotation direction B of the magnetic disk 12.

[0024] Next, the management of the data area information of the magnetic disk 12 in the present embodiment will be described. As a premise, the general characteristics of the magnetic disk 12 will be first described. FIG. 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 magnetic disk 12. The data area 110 of the magnetic 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.

[0025] As shown in FIG. 3, in the magnetic disk 12, the data area 110 is located 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 magnetic disk 12 and record and reproduce data with respect to the data area 110.

[0026] In the example shown in FIG. 3, the region between the dashed line C31 and the dashed line C32 is the floating guarantee region. The dashed line C31 indicates the outermost circumference of the floating guarantee region, and the dashed line C32 indicates the innermost circumference of the floating guarantee region (the innermost circumferential radius position of the floating guarantee region). In order to efficiently increase the recording capacity of the HDD10, the outermost circumference C31 of the floating guarantee region should be brought as close as possible to the outer edge of the magnetic disk 12, and the data region 110 should be made as large as possible.

[0027] FIG. 4 is a diagram showing a comparison of the floating degree of the magnetic head between the floating guarantee region of the magnetic head and the outside of the region. In FIG. 4, the horizontal axis indicates the distance (floating gap) between the disk surface of the magnetic disk and the magnetic head (for example, the ABS of the slider), and the vertical axis indicates the output value of the AE (Acoustic Emission) sensor. The AE sensor is a contact sensor provided on the slider of the magnetic head of the HDD tester, detects the contact between the disk surface and the magnetic head, and the detection output increases as the two come into stronger contact. Therefore, according to the detection output of the AE sensor, it is possible to determine to what extent the slider of the magnetic head can float with respect to the disk surface. That is, if it is known at what floating gap the slider of the magnetic head records and reproduces with respect to the magnetic disk, the floating guarantee region of the magnetic head can be determined.

[0028] In FIG. 4, the thick line L41 indicates the trajectory of the floating state of the magnetic head in the floating guarantee region, and the thin line L42 indicates the trajectory of the floating state of the magnetic head outside the floating guarantee region. As shown by the thin line L42 in FIG. 4, outside the floating guarantee region, when the gap between the disk surface and the magnetic head becomes narrower than X42, the detection output of the AE sensor rises sharply. On the other hand, as shown by the thick line L41 in FIG. 4, in the floating guarantee region, 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 floating guarantee of the magnetic head, and in the illustrated example, it corresponds to the value of the detection output of the AE sensor at the gaps X41 and X42.

[0029] In the illustrated example, a floating guarantee value of the magnetic head is set to a value of gap X4A that is smaller than gap X42 and larger than gap X41. In other words, if the detection output of the AE sensor rapidly increases at gap X4A, which is the floating guarantee value, for example, it can be estimated that the region of the disk surface inside the position of the magnetic head at that time is within the floating guarantee region.

[0030] As shown in FIGS. 2 and 3, the magnetic disk 12 is formed by applying a plurality of layers (three layers in the illustrated example) of films on the surface of the substrate 101. In order to properly maintain the posture of the substrate 101 during these film depositions, it is necessary to hold the substrate 101. In the example of the film deposition process shown in FIG. 3, the substrate 101 is held by a holder 90. The holder 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 holders 90 for holding the substrate 101 is not particularly limited. In the illustrated example, the posture of the substrate 101 is held by three holders 91, 92, and 93.

[0031] When the substrate 101 is held by the holder 90, the film thickness at the portion held by the holder 90 during film deposition on the substrate 101 is different from that at the portion not held. That is, in the magnetic disk 12, a portion (hereinafter referred to as the holder influence portion) 80 where the thickness (film thickness) of the film (for example, the perpendicular magnetic recording layer 103) is different from that at the portion not held is formed at the portion of the substrate 101 held by the holder 90. Therefore, the thickness of the film formed on the substrate 101 is not uniform but non-uniform.

[0032] In the illustrated example, for the magnetic disk 12, there are three holder influence portions 81, 82, and 83, one at each location held by the three holders 91, 92, and 93. These holder influence portions 81, 82, and 83 extend in the off-track direction from the outer peripheral surface 101a pressed by the holders 91, 92, and 93. The holder influence portions 81, 82, and 83 in the illustrated example have a triangular shape whose width gradually narrows as it goes toward the inside in the off-track direction (the center of the magnetic disk 12). However, the planar shape of the holder influence portions 81, 82, and 83 is not limited to such a triangular shape. Also, although the planar shapes of the holder influence portions 81, 82, and 83 are shown to be the same for convenience, their actual planar shapes are not the same.

[0033] Figure 5 is a diagram showing the displacement (change in film thickness) of the film formed on the substrate 101 of the magnetic disk 12 in the track where the holder influence portions 81, 82, and 83 are present. In Figure 5, the horizontal axis indicates the circumferential position, and the vertical axis indicates the displacement of the film. The displacement of the film here is shown as the degree of change in film thickness when the film thickness in a location where the holder influence portions 81, 82, and 83 do not exist (hereinafter referred to as the normal region) is set to 0. In the example shown in Figure 5, at the circumferential positions P81, P82, and P83 corresponding to the holder influence portions 81, 82, and 83, the film thickness changes rapidly with respect to the normal region. As for the displacement of the film, assume the case where the film thickness rapidly decreases (becomes thinner), that is, when the holder influence portions 81, 82, and 83 are recesses with respect to the normal region. However, there may also be a case where the film thickness rapidly increases (becomes thicker), that is, when the holder influence portions 81, 82, and 83 are protrusions with respect to the normal region.

[0034] Thus, in the holder influence portion 80, the film is displaced (the film thickness changes) with respect to the normal region. That is, the gap between the disk surface of the magnetic disk 12 and the magnetic head 16 changes between the holder influence portion 80 and the normal region. However, when performing a test on the floating guarantee of the magnetic head as described with reference to Figure 4, there may be a case where the detection output of the AE sensor does not increase in the holder influence portion 80 and becomes below the allowable value. In this case, it may be erroneously determined that the holder influence portion 80 is a normal region, in other words, that the holder influence portion 80 is included in an appropriate floating guarantee region.

[0035] On the other hand, when the slider 15 of the magnetic head 16 passes over the disk surface of the rotating magnetic disk 12, a shearing force acts between the slider 15 and the disk surface. FIG. 6 is a plan view for explaining the mode of the shearing force generated between the slider 15 and the disk surface.

[0036] As shown by the two-dot chain line in FIG. 6, for example, when the slider 15 of the magnetic head 16 is located near the inner circumference of the magnetic disk 12, the center line of the arm 26 of the carriage assembly 20 is in a state along the circumferential direction (rotation direction B) of the magnetic disk 12. At this time, a shearing force acts in the direction along the center line of the arm 26 between the slider 15 passing over the disk surface of the rotating magnetic disk 12 and the disk surface. The center line of the arm 26 is a virtual line (the one-dot chain line L6 shown in FIG. 6) connecting the rotation center C20 of the bearing portion 24 of the carriage assembly 20 and the center C15 of the slider 15.

[0037] On the contrary, as shown by the solid line in FIG. 6, for example, when the slider 15 of the magnetic head 16 is located near the outer circumference of the magnetic disk 12, the center line L6 of the arm 26 is inclined at a predetermined angle with respect to the circumferential direction (rotation direction B) of the magnetic disk 12 at the position of the slider 15 passing over the disk surface of the rotating magnetic disk 12. At this time, a shearing force as shown by the solid arrow F6 in FIG. 6 acts between the slider 15 passing over the disk surface of the rotating magnetic disk 12 and the disk surface.

[0038] Such a shearing force F6 has a component in a direction crossing the track of the magnetic disk 12 with respect to the arm 26 (the component indicated by the dashed arrow F61 in FIG. 6; hereinafter referred to as the component force F61). Due to the action of such a component force F61, the arm 26 of the carriage assembly 20, and specifically the slider 15 of the magnetic head 16, vibrates in the off-track direction. Hereinafter, such vibration is referred to as off-track vibration. When the slider 15 passes over the holder influence portion 80, since the gap between the magnetic head 16 and the disk surface changes, 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.

[0039] FIG. 7 is a diagram showing the mode of off-track vibration generated in the slider 15 of the magnetic head 16. FIG. 7 shows the mode of off-track vibration of the slider 15 corresponding to the displacement of the film of the substrate 101 (change in film thickness). Here, the mode of off-track vibration in the track of the magnetic disk 12 where the holder influence portions 81, 82, 83 as shown in FIG. 5 exist is shown.

[0040] As shown in FIG. 7, the slider 15 vibrates off-track corresponding to the sudden change in film thickness with respect to the normal region at the circumferential positions P81, P82, P83. That is, in regions other than the circumferential positions P81, P82, P83 corresponding to the holder influence portions 81, 82, 83, that is, within the normal regions S92, S94, S96, it hardly vibrates off-track. On the contrary, within the ranges S91, S93, S95 of the circumferential positions P81, P82, P83 corresponding to the holder influence portions 81, 82, 83, it vibrates off-track. In other words, in the holder influence portions 81, 82, 83, the amplitude of the off-track vibration becomes 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.

[0041] As long as the amplitude of the off-track vibration remains within an acceptable range, the occurrence of the off-track vibration itself is not particularly problematic. The off-track vibration, specifically the maximum amplitude of the off-track vibration, is temperature-dependent. This is because the damping material (vibration damping material) mounted on the support that supports the slider 15 of the magnetic head 16 has temperature characteristics. The temperature here is the ambient temperature (environmental temperature) of the HDD 10. Generally, when the ambient temperature becomes low, the damping performance deteriorates, so the amplitude of the off-track vibration increases.

[0042] FIG. 8 is a diagram showing the relationship between the temperature and the off-track vibration in the test apparatus of the HDD 10. In FIG. 8, the horizontal axis represents the temperature (ambient temperature), and the vertical axis represents the maximum amplitude of the off-track vibration. In such a test apparatus, there is a holder influence portion 80 on the magnetic disk 12. FIG. 8 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 test apparatus of the HDD 10. Here, as an example, when the magnetic head 16 records and reproduces data on a predetermined track of the magnetic disk 12 mounted on the test apparatus 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 are shown. In FIG. 8, the solid lines L81, L82, and L83 are the trajectories corresponding to the respective results when 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.

[0043] In FIG. 8, 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 highest temperature of the ambient temperature in which the operation of the HDD 10 is assumed, and is about 60° C. (hereinafter referred to as high temperature) as an example. The minimum operating temperature X8L is the lowest temperature of the ambient temperature in which the operation of the HDD 10 is assumed, and is about 5° C. (hereinafter referred to as low temperature) as an example. On the other hand, 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 at the time of the test, and is room temperature (about 30° C.) here. Such a test is executed when setting the outer edge position of the data area 110 in the HDD 10 described later.

[0044] In the temperature characteristics indicated by the solid line L81 and the temperature characteristics indicated by the solid line L82 in FIG. 8, the maximum amplitude of the off-track vibration is below the value of the allowable value (hereinafter referred to as the allowable off-track vibration amplitude) Y81 at the highest operating temperature X8H and the measured temperature X8A, that is, at both 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 lowest operating temperature X8L, that is, at low temperature. That is, at a temperature lower than the measured temperature X8A and higher than the lowest operating temperature X8L, the maximum amplitude of the off-track vibration exceeds the value of the allowable off-track vibration amplitude Y81.

[0045] On the other hand, in the temperature characteristics indicated by the solid line L83 in FIG. 8, the maximum amplitude of the off-track vibration is below the value of the allowable off-track vibration amplitude Y81 at the highest operating temperature X8H and the measured temperature X8A, that is, at both high temperature and normal temperature. Furthermore, the maximum amplitude of the off-track vibration is also below the value of the allowable off-track vibration amplitude Y81 at the lowest operating temperature X8L, that is, at low temperature. That is, in any case of high temperature, normal temperature, and low temperature, the maximum amplitude of the off-track vibration remains within the range of the allowable off-track vibration amplitude Y81.

[0046] Therefore, when the maximum amplitude of the off-track vibration at the measured temperature X8A, that is, at normal temperature, is equal to or less than the value (hereinafter referred to as the allowable off-track vibration amplitude threshold) Y82 in the temperature characteristics indicated by the solid line L83, it can be estimated that according to the temperature characteristics indicated by the solid line L83, the maximum amplitude of the off-track vibration at the lowest operating temperature X8L, that is, at low temperature, can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81.

[0047] In this case, when the measurement temperature X8A, that is, the maximum amplitude of the off-track vibration at room temperature, is equal to or less than a predetermined threshold value Y8A, it can be more reliably estimated that the maximum amplitude of the off-track vibration at the minimum operating temperature X8L, that is, at low temperature, can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81. The predetermined threshold value 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 value Y82. As an example, it is the allowable off-track vibration amplitude reference value Y9 described later.

[0048] Here, as shown in FIGS. 3 and 6, the holder influence portion 80 extends inward in the off-track direction from the outer peripheral surface 101a of the substrate 101 of the magnetic disk 12. Therefore, the off-track vibration generated in the slider 15 of the magnetic head 16 when passing over the holder influence portion 80 becomes smaller in the region closer to the inner side in the off-track direction. That is, the influence of the holder influence portion 80 on the off-track vibration becomes smaller in the region closer to the inner side in the off-track direction.

[0049] Therefore, in the present embodiment, the slider 15 is moved to a radius position at which the maximum amplitude of the off-track vibration becomes equal to or less than the allowable off-track vibration amplitude Y81, and the test is performed and repeatedly evaluated. Thereby, the radius position of the magnetic disk 12 at which the maximum amplitude of the off-track vibration of the slider 15 becomes the allowable off-track vibration amplitude Y81 can be set.

[0050] FIG. 9 is a diagram showing the relationship between the radius position of the magnetic disk 12 and the off-track vibration in the HDD 10. In FIG. 9, the horizontal axis represents the radius position of the magnetic disk 12, that is, the distance from the rotation center of the magnetic disk 12, and the vertical axis represents the maximum amplitude of the off-track vibration. X91 represents the innermost radius position (innermost circumference of the floating guarantee area) of the floating guarantee area of the magnetic head 16 that records and reproduces data on the magnetic disk 12, and X92 represents the outermost radius position (outermost circumference of the floating guarantee area) of the floating guarantee area. Further, X93 represents the outer edge position of the magnetic 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).

[0051] As shown in FIG. 9, 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 maintains a substantially constant value, and suddenly increases just before the outermost circumference X92 of the floating guarantee area. Then, 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 to the outer edge position (disk outer edge portion) X93. The predetermined threshold value at this time is the allowable off-track vibration amplitude reference value Y9.

[0052] The allowable off-track vibration amplitude reference value Y9 is set based on the allowable off-track vibration amplitude Y81 shown in FIG. 8. For example, it is set to a value smaller than the value of the allowable off-track vibration amplitude Y81, and as an example, it is set to a predetermined value (predetermined threshold value Y8A shown in FIG. 8) that is smaller than the value of the allowable off-track vibration amplitude Y81 and larger than the allowable off-track vibration amplitude threshold value Y82.

[0053] According to such a setting, when the maximum amplitude of the off-track vibration at the measurement temperature X8A, that is, at room temperature, is equal to or less than the allowable off-track vibration amplitude reference value Y9, it can be more reliably estimated according to the example shown in FIG. 8 that the maximum amplitude of the off-track vibration at the minimum operating temperature X8L, that is, at low temperature, can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81.

[0054] Therefore, in FIG. 9, the value X9A of the radius position of the magnetic 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. Thereby, at the radius position X9A of the data area 110, the maximum amplitude of the off-track vibration of the slider 15 of the magnetic head 16 can be surely suppressed to be equal to or less than the allowable off-track vibration amplitude Y81.

[0055] In the example shown in FIG. 9, the cause of the off-track vibration is the holder influence portion 80. Therefore, in the region of the magnetic disk 12 other than the holder influence portion 80, the off-track vibration caused by the holder influence portion 80 is minimized, and specifically, its maximum amplitude is suppressed to be equal to or less than the allowable off-track vibration amplitude Y81. For this reason, among the data regions 110, the region of the magnetic disk 12 other than the holder influence portion 80 is extended up to the outermost circumference X92 of the floating guarantee region. In other words, among the data regions 110, the region corresponding to the holder influence portion 80 is narrowed to the inside of the outermost circumference X92 of the floating guarantee region.

[0056] FIG. 10 is a plan view showing the mode of the data region 110 of the magnetic disk 12 in the HDD 10 according to the present embodiment. In the illustrated example, there are three holder influence portions 81, 82, and 83 on the magnetic disk 12. These three holder influence portions 81, 82, and 83 extend beyond the outermost circumference X92 of the floating guarantee region toward the inside in the off-track direction from the outer edge portion X93 of the disk. That is, the three holder influence portions 81, 82, and 83 have portions (hereinafter referred to as extension portions) 81a, 82a, and 83a located inside the outermost circumference X92 of the floating guarantee region.

[0057] As shown in FIG. 10, the outer edge 110a of the data area 110 of the magnetic disk 12 enters the inner side in the off-track direction, bypassing (avoiding) the extending portions 81a, 82a, 83a of the holder influence portions 81, 82, 83. Among the outer edge 110a of the data area 110, the portion corresponding to other than the extending portions 81a, 82a, 83a (hereinafter referred to as the first outer edge) 121 is set as the outermost peripheral radius position (outermost periphery of the floating guarantee area) of the floating guarantee area indicated by X92 in FIG. 9. The first outer edge 121 is continuously formed in an arc shape concentric with the magnetic disk 12. On the other hand, among the outer edge 110a of the data area 110, the portion corresponding to the extending portions 81a, 82a, 83a (hereinafter referred to as the second outer edge) 122 is located on the inner peripheral side of the magnetic disk 12 with respect to the first outer edge 121. The second outer edge 122 is set as the radius position indicated by X9A in FIG. 9. The portion connecting between 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 sector where the holder influence portions 81, 82, 83 to be described later exist and the sector where the holder influence portions 81, 82, 83 do not exist. 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.

[0058] As a result, the data area 110 has a form in which the extending portions 81a, 82a, 83a, and in particular, the portions corresponding to the holder influence portions 81, 82, 83 are narrowed in a substantially rectangular concave shape with respect to the first outer edge 121 (outermost periphery X92 of the floating guarantee area). That is, the data area 110 has a form in which the portions corresponding to other than the extending portions 81a, 82a, 83a, and in particular, other than the holder influence portions 81, 82, 83 are extended from the second outer edge 122 to the first outer edge 121. In other words, the first outer edge 121, the second outer edge 122, and the third outer edge 123 define a concave portion 111 on the outer edge 110a of the data area 110. That is, the outer edge 110a of the data area 110 has concave portions 111 recessed toward the inner peripheral side of the magnetic disk 12 at least in part (three places in the illustrated example).

[0059] In the data area 110, at a location narrower than the first outer edge 121 (the outermost circumference X92 of the floating guarantee area), that is, the concave portion 111, corresponding to the holder influence portions 81, 82, and 83, recording and reproduction of data are prohibited. That is, the concave portion 111 is excluded from the data area 110. Whether to permit or prohibit (permissibility) recording and reproduction of data in this way is set in units of sectors of the track where the holder influence portions 81, 82, and 83 are present.

[0060] As described above, in the magnetic disk 12, the holder influence portions 81, 82, and 83 have a different film thickness (for example, the thickness of the perpendicular magnetic recording layer 103) from other locations. The concave portion 111 is arranged corresponding to the holder influence portions 81, 82, and 83 and is excluded from the data area 110. Therefore, the film thickness of the perpendicular magnetic recording layer 103 of the concave portion 111 is different from the film thickness of the perpendicular magnetic recording layer 103 of the data area 110.

[0061] FIG. 11 is a diagram schematically showing an example of whether recording and reproduction of data for each sector in each of a plurality of tracks of the magnetic disk 12 are permitted. Data can be recorded and reproduced for sectors where recording and reproduction of data are permitted, and data cannot be recorded and reproduced for sectors where recording and reproduction of data are prohibited. The magnetic disk 12 according to the illustrated example has m + 1 tracks to which track numbers from 0 to m are assigned. The track numbers are assigned in ascending order from the track existing at the outermost circumference X92 of the floating guarantee area as 0 and inward in the off-track direction from the track, and the track existing at the innermost circumference X91 of the floating guarantee area is m. Each of these tracks has n + 1 sectors to which sector numbers from 0 to n are assigned. m and n are arbitrary natural numbers and may be different or the same.

[0062] In the figure example, there are holder influence parts 80 in sector 4 and sector 5 of track 0, and sector 4 and sector 5 of track 1. Therefore, data recording and playback are prohibited for these four sectors. In FIG. 11, these prohibited sectors are shown shaded. In contrast, sectors other than sector 4 and 5 of track 0 and sectors other than sector 4 and 5 of track 1 allow data recording and playback. In addition, all sectors from sector 1 to sector n of each of tracks 2 to track m allow data recording and playback. That is, all sectors of all tracks located inside the off-track direction from track 1 allow data recording and playback. In FIG. 11, these permitted sectors are shown in white.

[0063] Whether data recording and playback are permitted for each sector in such a plurality of tracks is managed by, for example, a table (hereinafter referred to as a recording / playback permission table) in which values of a predetermined flag (hereinafter referred to as a recording / playback flag) are set. As an example, a value of 0 is set for the recording / playback flag for a sector where data recording and playback are permitted, and a value of 1 is set for the recording / playback flag for a sector where data recording and playback are prohibited, so that the two can be uniquely distinguished. Then, the values of these recording / playback flags are recorded in the recording / playback permission table for each sector of all tracks of the entire magnetic disk 12 of the HDD 10 and tabulated.

[0064] The recording / playback permission table is created by the data area management unit 46c of the MPU 46, for example, in a quality inspection (test) before shipment of the product (HDD 10), and is stored as data area information in the non-volatile memory of the memory 47 of the main controller 40. Then, the data area management unit 46c performs a process of assigning logical addresses to the sectors of the magnetic disk 12 (hereinafter referred to as LBA assignment process). The LBA assignment process is a process of assigning logical addresses to the magnetic disk 12 according to the recording / playback permission table, that is, according to the presence or absence of the holder influence part 80 of the magnetic disk 12. In the LBA assignment process, the data area management unit 46c appropriately assigns logical addresses to the sectors according to the values of the recording / playback flags of the sectors recorded in the recording / playback permission table.

[0065] For example, a logical address is assigned to a sector in which the value of the recording / reproducing flag is set to 0 and data recording / reproducing is permitted. On the other hand, a logical address is not assigned to a sector in which the value of the recording / reproducing flag is set to 1 and data recording / reproducing is prohibited. As a result, sectors where the holder influence portion 80 does not exist are assigned logical addresses and used as the data area 110 of the magnetic disk 12. On the contrary, sectors where the holder influence portion 80 exists are not assigned logical addresses and are excluded from the data area 110 of the magnetic disk 12.

[0066] As described above, according to the HDD 10 according to the present embodiment, even when the holder influence portion 80 exists on the magnetic disk 12, the off-track vibration of the slider 15 of the magnetic head 16 caused by the holder influence portion 80 can be suppressed to be equal to or less than the allowable off-track vibration amplitude Y81. At that time, based on the temperature characteristics of the maximum amplitude of the off-track vibration as shown in FIG. 8, the maximum amplitude of the off-track vibration at a low temperature (about 5°C) can be appropriately estimated under the condition that the ambient temperature of the HDD 10 is normal temperature (about 30°C).

[0067] Therefore, for example, when the temperature characteristics of the maximum amplitude of the off-track vibration are confirmed at normal temperature (about 30°C) or high temperature (about 60°C) at the time of shipment of the HDD 10, and the confirmation of the temperature characteristics at low temperature (about 5°C) is not performed from the viewpoint 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.

[0068] Further, according to the relationship between the radial position of the magnetic disk 12 and the off-track vibration in the HDD 10 as shown in FIG. 9, the outer edge 110a of the data area 110 can be set according to the temperature characteristics of the maximum amplitude of the off-track vibration.

[0069] Such an outer edge 110a is set in response to the off-track vibration caused by the holder influence portion 80 of the magnetic disk 12. For this reason, while setting the data area 110 corresponding to the holder influence portion 80 inside (the second outer edge 122) of the outermost periphery X92 of the floating guarantee area, 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. Thereby, even when the holder influence portion 80 exists on the magnetic disk 12, the data area 110 where data recording and reproduction are possible can be extended to the maximum extent.

[0070] Therefore, according to the present embodiment, even at low temperatures, 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, considering the change in the amplitude of the off-track vibration with respect to the change in the ambient temperature of the HDD 10, the data area 110 can be set, and it becomes possible to improve the recording density and reliability of the HDD 10.

[0071] As described above, the embodiments of the present invention have been described. However, such embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0072] 10…Magnetic disk device (HDD), 12…Magnetic disk, 15…Slider, 16…Magnetic head, 17…Head portion, 18…Head actuator, 20…Carriage assembly, 22…Voice coil motor (VCM), 24…Bearing portion, 26…Arm (suspension), 28…Wiring member (flexure), 30…Head amplifier IC, 40…Main controller, 42…R / W channel, 44…Hard disk controller (HDC), 45…Host, 46…Microprocessor (MPU), 46a…Write control unit, 46b…Read control unit, 46c…Data area management unit, 47…Memory, 48…Driver IC, 80, 81, 82, 83…Holder influence portion, 81a, 82a, 83a…Extension portion of the 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 the data area, 111…Recess, 121…First outer edge, 122…Second outer edge, 123…Third outer edge, C32…Innermost circumference of the floating guarantee area, C32…Innermost circumference of the floating guarantee area, X91…Innermost radius position of the floating guarantee area (innermost circumference of the floating guarantee area), X92…Outermost radius position of the floating guarantee area (outermost circumference of the floating guarantee area), X93…Disk outer edge portion (outer edge position of the magnetic disk (outer peripheral surface position of the substrate)), Y81…Allowable off-track vibration amplitude, Y82…Allowable off-track vibration amplitude threshold, Y8A, Y9…Allowable off-track vibration amplitude reference value.

Claims

1. 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, wherein an outer edge of the data area has a first outer edge, a second outer edge located on an inner circumferential side of the magnetic disk with respect to the first outer edge, and a third outer edge connecting between the first outer edge and the second outer edge, and has a recess recessed toward the inner circumferential side of the magnetic disk at least in part. A magnetic disk device.

2. The magnetic disk has a substrate and a magnetic recording layer provided on a surface of the substrate, wherein a film thickness of the magnetic recording layer in the recess is different from a film thickness of the magnetic recording layer in the data area. The magnetic disk device according to claim 1.

3. In a circumferential direction of the magnetic disk, the recess is arranged corresponding to a position where the substrate is held by a holder during film formation of the magnetic recording layer. The magnetic disk device according to claim 2.

4. The first outer edge and the second outer edge are set at a radius position of the magnetic disk where a maximum amplitude of an off-track vibration in a radial direction of the magnetic disk generated in the magnetic head during recording or reproducing of the data with respect to the magnetic disk is equal to or less than a predetermined threshold value. The magnetic disk device according to claim 3.

5. The first outer edge is set at an outermost peripheral radius position of a region where the magnetic head can float with respect to a surface of the magnetic disk. The magnetic disk device according to claim 4.

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

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