Magnetic disk device and control method thereof

Abstract

A magnetic disk device and a control method thereof are provided. The magnetic disk device includes a magnetic disk, a magnetic head, and a controller that controls a movement and a protrusion amount of the magnetic head, the controller detects a first optimal floating amount, which is an optimal pitch between a predetermined position of the magnetic disk and the magnetic head, and estimates a first optimal floating amount distribution based on the first optimal floating amount. The amount of protrusion of the magnetic head is controlled so that the pitch between the magnetic head and the magnetic disk is distributed according to a first optimal floating amount, and the magnetic head is moved, thereby obtaining the movable distance and the optimal moving speed of the magnetic head. Sequentially positioning the moving position of the magnetic head to a plurality of moving positions determined on the basis of the movable distance and the optimal moving speed, and respectively detecting a second optimal floating amount at each moving position; a plurality of spiral servo patterns are written into the magnetic disk by the magnetic head while sequentially positioning the magnetic head to the plurality of movement positions and simultaneously moving the magnetic head, and controlling the protruding amount of the magnetic head so that the pitch between the magnetic head and the magnetic disk at each movement position becomes a first optimal floating amount and each second optimal floating amount.

Description

[0001] This application claims the priority of Japanese Patent Application No. 2023-151949 (filing date: September 20, 2023) as a basic application. The present application incorporates the entire contents of the basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to a magnetic disk device and a control method thereof. Background Art

[0003] In a magnetic disk device having a magnetic disk and a magnetic head for writing and reading data from the magnetic disk, a process of writing a servo pattern of a magnetic disk whose recording surface is blank, i.e., self-servo writing (SSW) is performed. During this execution, the magnetic disk device performs a touch-down process, which is a process of moving the magnetic head along the radial direction of the magnetic disk to the innermost peripheral position where the movement is restricted by a stopper, and making the magnetic head contact (land) with the recording surface of the magnetic disk at the innermost peripheral position. By performing this touch-down process, the spacing between the magnetic head and the recording surface of the magnetic disk, i.e., the floating amount of the magnetic head, can be adjusted to a state suitable for the innermost peripheral position of the magnetic disk.

[0004] However, in the stage of performing self-servo writing, there is no pattern for positioning on the recording surface of the disk. Therefore, in other areas of the disk except the innermost peripheral position, it is difficult to perform positioning (also called tracking) of the magnetic head and landing processing based on the positioning. Therefore, in other areas of the disk except the innermost peripheral position, the floating amount of the magnetic head cannot be set to an appropriate state. Since the floating amount of the magnetic head cannot be set to an appropriate state, it is impossible to perform high-precision self-servo writing for the disk. Summary of the invention

[0005] The present embodiment provides a magnetic disk device capable of executing high-precision self-servo writing and a control method thereof.

[0006] A magnetic disk device according to one embodiment comprises: a magnetic disk; a magnetic head capable of moving relative to the magnetic disk and capable of protruding toward the magnetic disk side and adjusting the protrusion amount; and a controller for controlling the movement of the magnetic head and the protrusion amount of the magnetic head, wherein the controller detects a first optimal floating amount as an optimal spacing between a predetermined position of the magnetic disk and the magnetic head, estimates a first optimal floating amount distribution as an optimal spacing between the magnetic head and the magnetic disk at a plurality of moving positions of the magnetic head based on the first optimal floating amount, and controls the protrusion amount of the magnetic head so that the spacing between the magnetic head and the magnetic disk is in accordance with the first optimal floating amount distribution. The magnetic head moves to find out the movable distance and the optimal moving speed of the magnetic head, and sequentially positions the moving position of the magnetic head to multiple moving positions determined based on the movable distance and the optimal moving speed, and respectively detects the second optimal floating amount as the optimal spacing between the magnetic head and the magnetic disk at each moving position, and sequentially positions and moves the magnetic head to multiple moving positions determined based on the movable distance and the optimal moving speed, and controls the protrusion amount of the magnetic head in such a way that the spacing between the magnetic head and the magnetic disk at each moving position becomes the first optimal floating amount and the second optimal floating amount, and writes multiple spiral servo patterns to the magnetic disk through the magnetic head. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a block diagram showing the structure of one embodiment.

[0008] Figure 2 It is a perspective view showing each magnetic head and each magnetic disk in this embodiment.

[0009] Figure 3 It is a plan view showing an example of each servo pattern involved in this embodiment.

[0010] Figure 4 It is a diagram showing a cross section of main parts of a magnetic head and a magnetic disk in this embodiment.

[0011] Figure 5 It is a diagram showing a first optimum floating amount and a first floating amount distribution at a moving position of the magnetic head in this embodiment.

[0012] Figure 6 It is a diagram showing a first optimum floating amount and a second optimum floating amount and a first floating amount distribution and a second floating amount distribution at a moving position of a magnetic head in this embodiment.

[0013] Figure 7 It is a plan view showing the recording surface of the magnetic disk on which each first spiral servo pattern is written in this embodiment.

[0014] Figure 8 It is a plan view showing the recording surface of the magnetic disk on which each second spiral servo pattern is written in this embodiment.

[0015] Fig. 9 It is a plan view showing the recording surface of the magnetic disk on which each third spiral servo pattern is written in this embodiment.

[0016] Fig.10 : is a flowchart showing the self-servo writing in this embodiment.

[0017] Fig.11 is a flowchart illustrating a landing process in one embodiment.

[0018] Description of Reference Numerals

[0019] 10…disk device, 12…disk, 16…magnetic head, 16W…write head, 40…main controller, 46c…heater control unit, 46d…calculation unit, 47…memory, 74…detection unit, BO…retraction amount, D1…first distribution, D2…second distribution, F1…first floating amount, F2…second floating amount, H…heater, N…number of detections, P1…first position, P2…second position, RL…ramp loading mechanism, S…recording surface, SV1…first spiral servo pattern, SV2…second spiral servo pattern, SV3…third spiral servo pattern, X…ratio. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the disclosure is only an example, and appropriate changes that retain the gist of the invention that can be easily thought of by a person skilled in the art are of course included in the scope of the present invention. In addition, in order to make the drawings and descriptions clearer, there are cases where the width, thickness, shape, etc. of each part are schematically represented compared to the actual form, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, for the same elements as those described in the previous figures, the same figure numbers are sometimes marked and the detailed description is appropriately omitted.

[0021] Below, while referring to the attached Figure 1 A magnetic disk device and a control method thereof according to one embodiment will be described in detail.

[0022] Figure 1 1 shows the structure of the magnetic disk device 10. The magnetic disk device 10 includes a rectangular housing 11, a magnetic disk 12 as a recording medium arranged in the housing 11, a spindle motor 14 that supports and rotates the magnetic disk 12, and a plurality of magnetic heads 16 that write (record) and read (reproduce) data from the magnetic disk 12.

[0023] The magnetic disk device 10 includes a head actuator 18 for moving and positioning the magnetic head 16 to an arbitrary track on the magnetic disk 12. The head actuator 18 includes a carriage assembly 20 for movably supporting the magnetic head 16 and a voice coil motor (VCM) 22 for rotating the carriage assembly 20.

[0024] The carriage assembly 20 includes a bearing 24 rotatably supported by the housing 11 and a plurality of suspensions 26 extending from the bearing 24. The magnetic head 16 is supported at the top of each suspension 26 and moves along the track T when the carriage assembly 20 rotates.

[0025] The magnetic disk device 10 includes a stopper ST for limiting the movement of the magnetic head 16 and a ramp loading mechanism RL capable of holding the magnetic head 16. The stopper ST prevents the magnetic head 16 from excessively moving toward the inner peripheral side relative to the magnetic disk 12. More specifically, the movement of the magnetic head 16 is limited by contacting the VCM 22 that rotates around the bearing portion 24 with the stopper ST.

[0026] The ramp load mechanism RL is located in a region where the magnetic head 16 can move, and is located outside the outermost periphery of the magnetic disk 12 in the radial direction.

[0027] According to the above configuration, the magnetic head 16 can move (also referred to as seek) along the track T between the first position P1 where the movement is limited by the stopper ST and the second position (unloading position) P2 held by the ramp loading mechanism RL. In one example, the first position P1 exists in the innermost area of ​​the magnetic disk 12. The second position is a position corresponding to the outer periphery of the magnetic disk 12.

[0028] The magnetic disk device 10 includes a head amplifier IC (preamplifier) ​​30 for driving the magnetic head 16, a main controller 40, and a driver IC 48. The head amplifier IC 30 is electrically connected to the magnetic head 16. The head amplifier IC 30 includes a recording current supply circuit 32 for supplying a recording current to a recording coil of the magnetic head 16, and a heater power supply circuit 34 for supplying power to a heater H described later.

[0029] The main controller 40 and the driver IC 48 are formed on, for example, a control circuit substrate (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 (HDC) 44, a microprocessor (MPU) 46, a memory 47, etc. The main controller 40 is electrically connected to the VCM 22 and the spindle motor 14 via the driver IC 48. The HDC 44 can be connected to a host computer (host) 45.

[0030] The R / W channel 42 is a signal processing circuit for reading / writing data. The HDC 44 controls data transmission between the host 45 and the R / W channel 42 according to instructions from the MPU 46. The HDC 44 is electrically connected to the R / W channel 42, the MPU 46, the memory 47, etc. The memory 47 includes a volatile memory and a non-volatile memory. For example, the memory 47 includes a buffer memory composed of a DRAM and a flash memory. The memory 47 stores programs and parameters required for the processing of the MPU 46.

[0031] The MPU 46 is the control center of the magnetic disk device 10, and performs the control of the read / write action and the servo control required for the positioning of the magnetic head 16. That is, the MPU 46 includes a write control unit 46a that controls the write process, a read control unit 46b that controls the read process, a heater control unit 46c that controls the value of the power supplied to the heater H described later, a calculation unit 46d that calculates the protrusion amount of the magnetic head 16 described later, and a self-servo control unit 46e that performs servo control such as self-servo writing.

[0032] The write control unit 46a controls data writing processing according to a command from the host computer 45, etc. Specifically, the write control unit 46a controls the VCM 22 via the driver IC 48, places the magnetic head 16 at a predetermined position on the magnetic disk 12, and writes data.

[0033] The read control unit 46b controls the data read process according to a command from the host computer 45, etc. Specifically, the read control unit 46b controls the VCM 22 via the driver IC 48, places the magnetic head 16 at a predetermined position on the magnetic disk 12, and reads data.

[0034] The calculation unit 46d calculates the protrusion amount of the magnetic head 16 based on the "relationship between the power supply value supplied to the heater H and the protrusion amount of the magnetic head 16" pre-stored in the memory 47 and the actual power supply value supplied to the heater H controlled by the heater control unit 46c.

[0035] The self-servo control unit 46e performs control of so-called self-servo writing (SSW) which is a process of writing a servo pattern to the magnetic disk 12. This control includes a landing process of the magnetic head 16 involved in the self-servo writing.

[0036] [Protrusion Amount of Magnetic Head 16]

[0037] When power is supplied to the heater H, the heater H generates heat, and due to the heat, the head face 13, which is a mounting portion of the magnetic head 16 to be described later, of the write head 16W and the read head 16R, thermally expands. Due to the thermal expansion, the write head 16W and the read head 16R of the magnetic head 16 protrude toward the magnetic disk 12 and approach the recording surface S to be described later of the magnetic disk 12. The protrusion amount of the write head 16W and the read head 16R is also referred to as the protrusion amount of the magnetic head 16.

[0038] By controlling the power supplied to the heater H, the protrusion amount of the magnetic head 16 can be adjusted. By adjusting the protrusion amount, the distance between the magnetic head 16 (the write head 16W and the read head 16R) and the recording surface S of the magnetic disk 12, i.e., the so-called spacing, can be adjusted. This spacing is called the floating amount of the magnetic head 16.

[0039] If the power supplied to the heater H is gradually increased from a state of 0, the protrusion amount of the magnetic head 16 gradually increases and the floating amount of the magnetic head 16 gradually decreases. If the power supplied to the heater H is further increased, the protrusion amount of the magnetic head 16 further increases, and finally the write head 16W and the read head 16R are in contact with the recording surface S of the magnetic disk 12 in a landing state. The floating amount of the magnetic head 16 at the time of landing is 0. If the power supplied to the heater H is reduced from this landing state, the protrusion amount of the magnetic head 16 is reduced, and the write head 16W and the read head 16R are separated from the recording surface S of the magnetic disk 12 and the floating amount of the magnetic head 16 is greater than 0.

[0040] The distance (floating amount) between the magnetic head 16 and the recording surface S of the magnetic disk 12 can be adjusted to an optimal state based on the protrusion amount of the magnetic head 16 when the magnetic head 16 lands on the recording surface S of the magnetic disk 12 (the power supplied to the heater H). The optimal state refers to a distance (floating amount) at which the magnetic head 16 does not contact the recording surface S of the magnetic disk 12 and each spiral servo pattern described later can be written to the recording surface S of the magnetic disk 12 with high precision by the magnetic head 16.

[0041] The calculation unit 46d can calculate the protrusion amount of the magnetic head 16 when the magnetic head 16 lands on the recording surface S of the magnetic disk 12 based on the power supplied to the heater H when the magnetic head 16 lands on the recording surface S of the magnetic disk 12. The self-servo control unit 46e can detect the optimal floating amount as a pitch suitable for self-servo writing based on the protrusion amount of the magnetic head 16 calculated by the calculation unit 46d when the magnetic head 16 lands on the recording surface S of the magnetic disk 12 while performing the landing process of landing the magnetic head 16 on the recording surface S of the magnetic disk 12, and adjust the protrusion amount of the magnetic head 16 so as to achieve the optimal floating amount.

[0042] [Configuration of the Magnetic Disk 12 and the Magnetic Head 16]

[0043] like Figure 2As shown, the magnetic disk device 10 includes a plurality of circular magnetic disks 12 coaxially fitted with a rotation shaft 14 a of a spindle motor 14 , and a plurality of magnetic heads 16 disposed with respect to the magnetic disks 12 .

[0044] Each magnetic disk 12 has a recording surface S on the upper surface side and the lower surface side. These recording surfaces S include a plurality of tracks Tr formed along the circumferential direction of the magnetic disk 12, and a plurality of sectors C formed by dividing these tracks Tr in the circumferential direction. The plurality of tracks Tr are arranged in a radial direction of the magnetic disk 12. Each magnetic disk 12 is driven to rotate at a predetermined speed by a spindle motor 14.

[0045] Each magnetic head 16 is arranged to face one recording surface S of each magnetic disk 12. The main controller 40 can control each magnetic head 16. For example, the main controller 40 can control the heater power supply circuit 34 by the heater control unit 46c to adjust the power value supplied to the heater H of each magnetic head 16.

[0046] Figure 3 An example of a plurality of servo patterns written on the recording surface S of the magnetic disk 12 is shown. A plurality of servo patterns (also referred to as product servo patterns) PSV used in the magnetic disk device 10 as a final product and a plurality of auxiliary servo patterns BSV different from these product servo patterns PSV are written on the recording surface S of the magnetic disk 12. The plurality of auxiliary servo patterns BSV include a plurality of first spiral servo patterns (also referred to as CGS; Coarse Guide Spiral Pattern) SV1, a plurality of second spiral servo patterns (also referred to as FGS, Fine Guide Spiral Pattern) SV2, and a plurality of third spiral servo patterns (also referred to as FS, Final Spiral Pattern) SV3 described later.

[0047] The product servo pattern PSV is written on the recording surface S of the magnetic disk 12 by performing self-servo writing while using the auxiliary servo pattern BSV written in the process of self-servo writing on the blank disk for positioning control of the magnetic head 16 .

[0048] Figure 4 The main parts of the magnetic head 16 and the magnetic disk 12 are shown in an enlarged manner. The magnetic head 16 includes a write head 16W and a read head 16R formed by a thin film process at the end of the slider 15, and is formed as a separate head. The slider 15 has a head surface (ABS; AirBearing Surface: air bearing surface) 13, which is a surface facing the recording surface S of the magnetic disk 12 in order to float from the recording surface S of the magnetic disk 12. The write head 16W writes data to the recording surface S of the magnetic disk 12. The read head 16R reads the data written to the recording surface S of the magnetic disk 12.

[0049] The magnetic disk 12 is configured as a perpendicular magnetic recording medium. The magnetic disk 12 has, for example, a substrate 101 formed in a disk shape with a diameter of 96 mm (about 3.5 inches) and made of a non-magnetic body. On each surface (recording surface S) of the substrate 101, a soft magnetic layer 102 as a base layer and 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 sequentially stacked.

[0050] The read head 16R includes a magnetoresistance effect element 55, and includes a first magnetic shielding film 56 and a second magnetic shielding film 57 arranged so as to sandwich the magnetoresistance effect element 55 in the longitudinal direction LD of the recording track formed in the perpendicular magnetic recording layer 103 of the magnetic disk 12. The magnetoresistance effect element 55 and the magnetic shielding films 56 and 57 extend substantially perpendicularly to the head face 13. The lower end portions (top ends) of the magnetoresistance effect element 55 and the magnetic shielding films 56 and 57 protrude slightly from the head face 13.

[0051] The write head 16W includes a main magnetic pole 60, a return magnetic pole 62, a non-conductive body 52, a leading magnetic pole 64, a second connecting portion 67, a first recording coil 70, and a second recording coil 72. The main magnetic pole 60, the return magnetic pole 62, and the leading magnetic pole 64 are formed of a high magnetic permeability material. The main magnetic pole 60 and the return magnetic pole 62 constitute a first magnetic core forming a magnetic circuit. The main magnetic pole 60 and the leading magnetic pole 64 constitute a second magnetic core forming a magnetic circuit.

[0052] The main magnetic pole 60 extends substantially perpendicularly to the head surface 13. The top end portion 60a of the main magnetic pole 60 on the head surface 13 side is narrowed toward the head surface 13 and is formed into a columnar shape having a narrower width than other portions. The top end portion 60a of the main magnetic pole 60 protrudes slightly from the head surface 13 of the slider 15.

[0053] The return magnetic pole 62 is provided to efficiently close the magnetic circuit via the soft magnetic layer 102 of the magnetic disk 12 directly below the main magnetic pole 60. The return magnetic pole 62 is formed in a substantially L-shape. The top end portion 62a of the return magnetic pole 62 is formed in an elongated rectangular shape and slightly protrudes from the head face 13 of the slider 15. The top end portion 62a of the return magnetic pole 62 has a magnetic pole end face 62b that is opposite to the top end portion 60a of the main magnetic pole 60 with a write gap WG therebetween. The magnetic pole end face 62b extends perpendicularly or slightly inclined relative to the head face 13.

[0054] The return magnetic pole 62 has a first connection portion 50 connected to the main magnetic pole 60. The first connection portion 50 is magnetically connected to the upper portion of the main magnetic pole 60, that is, the portion of the magnetic pole 60 separated from the head surface 13, via the non-conductive body 52. ​​The first recording coil 70 is wound around the first connection portion 50 at the first magnetic core, for example. When writing a signal to the magnetic disk 12, a write current flows in the first recording coil 70, so that the first recording coil 70 excites the main magnetic pole 60 and causes magnetic flux to flow in the main magnetic pole 60.

[0055] The leading magnetic pole 64 is provided on the leading side of the main magnetic pole 60 so as to face the main magnetic pole 60. The leading magnetic pole 64 is formed in a substantially L-shape. The top end portion 64a on the head face 13 side of the leading magnetic pole 64 is formed in an elongated rectangular shape. The top end portion 64a protrudes slightly from the head face 13 of the slider 15. The top end portion 64a has a magnetic pole end face 64b facing the top end portion 60a of the main magnetic pole 60 with a gap therebetween.

[0056] The leading magnetic pole 64 has a second connecting portion 67 connected to the main magnetic pole 60 at a position away from the head surface 13. The second connecting portion 67 is formed of, for example, a soft magnetic body, and is magnetically connected to the upper portion of the main magnetic pole 60, that is, the portion of the main magnetic pole 60 away from the head surface 13, via the non-conductive body 59. Thus, the second connecting portion 67 forms a magnetic circuit together with the main magnetic pole 60 and the leading magnetic pole 64. The second recording coil 72 is, for example, wound around the second connecting portion 67 to apply a magnetic field to the magnetic circuit.

[0057] The magnetic head 16 further includes a heater (electric heater) H and a detection unit 74. The heater H is composed of a first heater H1 for heating the write head 16W and a second heater H2 for heating the read head 16R. The first heater H1 and the second heater H2 are connected to the head amplifier IC30 via wiring and connection terminals 43, respectively. The heater power supply circuit 34 of the head amplifier IC30 supplies power of a desired value to the first heater H1 and the second heater H2, respectively. When power is supplied to the first heater H1 and the second heater H2, as described above, the write head 16W and the read head 16R of the magnetic head 16 protrude toward the magnetic disk 12.

[0058] The heater H is not limited to being composed of two heaters, namely the first heater H1 and the second heater H2 , and may be composed of, for example, one heater that heats the write head 16W.

[0059] The detection unit 74 is disposed near the heater H, and in one example, is located between the first heater H1 and the second heater H2. The detection unit 74 can detect the contact (landing) of the magnetic head 16 with respect to the recording surface S of the magnetic disk 12. In addition, the detection unit 74 can detect that the magnetic head 16 is held in the ramp loading mechanism RL, that is, the magnetic head 16 moves to the second position P2.

[0060] The detection unit 74 is, for example, an HDI (Head Disk Interface) sensor that detects changes in resistance value due to temperature changes. Specifically, if the power supplied to the heater H is increased and the magnetic head 16 lands on the recording surface S of the magnetic disk 12, friction heat is generated between the magnetic head 16 and the magnetic disk 12, and the temperature of the HDI sensor changes (increases). At this time, the resistance value of the HDI sensor as a resistance element changes, so it can detect that the magnetic head 16 has landed on the recording surface S of the magnetic disk 12.

[0061] Here, a method of detecting that the magnetic head 16 is located at the second position P2 will be described.

[0062] When the magnetic head 16 moves from the first position P1 toward the second position P2, if the magnetic head 16 is on the magnetic disk 12, the temperature of the magnetic head 16 is kept constant by the air flowing into the head surface 13. When the magnetic head 16 reaches the second position P2, the cooling by the air disappears, so the temperature of the magnetic head 16 rises. By monitoring the change in the resistance of the HDI sensor as the detection unit 74, it is possible to detect whether the magnetic head 16 is located at the second position P2.

[0063] In addition, the method of detecting that the magnetic head 16 is located at the second position P2 is not limited to the above-described method, and a method of monitoring the current supplied to the VCM 22 may be used.

[0064] As described above, when the magnetic head 16 lands on the magnetic disk 12, the landing can be detected by the detection unit 74. And, the protrusion amount of the magnetic head 16 during the landing detection can be calculated by the calculation unit 46d. The self-servo control unit 46e can detect the optimal floating amount as a pitch suitable for self-servo writing based on the protrusion amount of the magnetic head 16 during the landing calculated by the calculation unit 46d, and adjust the protrusion amount of the magnetic head 16 in a manner to achieve the optimal floating amount.

[0065] [Self-servo writing]

[0066] Next, the blank disk self-servo writing executed by the main controller 40 will be described.

[0067] Figure 5 The relationship between the first optimum flying amount F1 of the magnetic head 16 and the position of the magnetic head 16 in the radial direction of the magnetic disk 12 is shown. Figure 6 The relationship between the first optimum flying amount F1 and the second optimum flying amount F2 of the magnetic head 16 and the position of the magnetic head 16 in the radial direction of the magnetic disk 12 is shown. Figure 7 The recording surface S of the magnetic disk 12 on which the first spiral servo pattern SV1 is written is shown. Figure 8 The recording surface S of the magnetic disk 12 on which the second spiral servo pattern SV2 is written is shown. Fig. 9The recording surface S of the magnetic disk 12 on which the third spiral servo pattern SV3 is written is shown. Fig.10 The steps of self-servo writing of a blank disk are shown.

[0068] like Fig.10 As shown, when the blank disk self-servo writing starts, the main controller 40 moves the magnetic head 16 facing one recording surface S (referred to as the first spiral surface S1) among the multiple recording surfaces S of each magnetic disk 12 to the first position P1 (S1) on the innermost circumference of the magnetic disk 12. At the first position P1, the main controller 40 performs a landing process for bringing the magnetic head 16 into contact with the first spiral surface S1, and detects the optimal spacing between the magnetic head 16 and the first spiral surface S1 at the first position P1 as the first optimal floating amount F1 (S2) based on the protrusion amount of the magnetic head 16 at the time when the magnetic head 16 lands on the first spiral surface S1.

[0069] The protrusion amount of the magnetic head 16 at the time when the head 16 lands on the first spiral surface S1 is calculated by the calculation unit 46d. The protrusion amount of the magnetic head 16 at the time when the magnetic head 16 lands at the first position P1 is referred to as the inner circumference side TD value.

[0070] Then, if Figure 5 As shown, the main controller 40 estimates the optimal spacing between the magnetic head 16 and the first spiral surface S1 at multiple moving positions z9, z8, z7, z6, z5, z4, z3, z2, z1, and z0 of the magnetic head 16 from the first position P1 to the second position P2 in the radial direction of the magnetic disk 12 as the first floating amount distribution D1 (S3) based on the first optimal floating amount F1 detected above and the reference floating amount distribution AVE pre-stored in the memory 47. Position z9 corresponds to the first position P1. The reference floating amount distribution AVE is a shift of the average value of multiple optimal floating amounts obtained in other magnetic disk devices in the past. The first floating amount distribution D1 takes the first optimal floating amount F1 as the starting point, and shifts according to the change of the reference floating amount distribution AVE while ensuring a predetermined margin between the first optimal floating amount F1 and the reference floating amount distribution AVE. The first floating amount distribution D1 is used in the following slope learning process for obtaining the movable distance and the optimal moving speed of the magnetic head 16.

[0071] After estimating the first floating amount distribution D1 (S3), the main controller 40 performs a ramp learning process (S4). The ramp learning process refers to a process of calculating the movable distance of the magnetic head 16 (the distance between the first position P1 and the second position P2) and determining the optimal moving speed (optimal seek speed) of the magnetic head 16 in the radial direction of the magnetic disk 12 based on the calculated movable distance. Specifically, in the ramp learning process, by adjusting the moving speed (seek speed) of the magnetic head 16 while repeatedly performing a loading (Load) action of moving the magnetic head 16 from the first position P1 (movement to) the second position P2 and an unloading (Unload) action of moving the magnetic head 16 from the second position P2 (return movement) to the first position P1, the movable distance of the magnetic head 16 between the first position P1 and the second position P2 is obtained, and the optimal moving speed of the magnetic head 16 is obtained.

[0072] As a method for determining the optimal moving speed of the magnetic head 16, for example, the moving speed of the magnetic head 16 is adjusted while monitoring the number of data sampled by the magnetic head 16 in one loading action, and the moving speed of the magnetic head 16 when the number of sampled data becomes a desired value is determined as the optimal moving speed. For example, in the case where the number of sampled data obtained in one loading action is, for example, "500" and the desired number of sampled data is, for example, "495", the moving speed of the magnetic head 16 is adjusted in such a way that the number of data sampled by the magnetic head 16 in one loading action becomes "495". The moving speed of the magnetic head 16 after the adjustment can be determined as the optimal moving speed. In addition, based on the time when the magnetic head 16 moves from the first position P1 to the second position P2 and the moving speed of the magnetic head 16, the movable distance of the magnetic head 16 from the first position P1 to the second position P2 can be calculated.

[0073] When the number of data sampled by the head 16 in one loading action is, for example, "500", it can be predicted that the middle position between the first position P1 and the second position P2 exists between the position where the number of data sampled by the head 16 becomes "250" and the position where the number of data sampled by the head 16 becomes "251".

[0074] That is, the moving position of the magnetic head 16 in the area between the first position P1 and the second position P2 can be determined by finding the movable distance of the magnetic head 16 from the first position P1 to the second position P2 and finding the optimal moving speed of the magnetic head 16. Since the moving position of the magnetic head 16 can be determined, high-precision positioning of the magnetic head 16 between the first position P1 and the second position P2 can be achieved.

[0075] During the loading and unloading operations of the magnetic head 16, the main controller 40 controls the power supplied to the heater H in such a manner that the distance between the magnetic head 16 and the first spiral surface S1 is between the first position P1 and the second position P2 according to the first optimal floating amount distribution D1 estimated above. Thus, the loading and unloading operations of the magnetic head 16 can be repeatedly performed in such a manner that the magnetic head 16 does not contact the first spiral surface S1 of the magnetic disk 12.

[0076] After the slope learning process of step S4 is performed, Figure 6 As shown, in the area from the first position P1 to the second position P2, including positions z8 to z0 other than the first position P1 (non-landing area), the main controller 40 sequentially positions the magnetic head 16 to a plurality of moving positions z8 to z0 determined based on the movable distance and the optimal moving speed obtained through the above-mentioned slope learning processing, and moves the magnetic head 16 at the optimal moving speed, and performs landing processing at each moving position of the moving position z8 to z0, thereby detecting the optimal spacing between the magnetic head 16 and the first spiral surface S1 at each moving position as the second optimal floating amount F2 (S5).

[0077] Next, the main controller 40 determines the transition of the first optimal flotation amount F1 suitable for the first position P1, that is, the position z9, and the plurality of second optimal flotation amounts F2 suitable for the movement positions z8 to z0 as the second flotation amount distribution D2 (S6). Figure 6 The second optimum flying amount distribution D2 is indicated by a dashed line in FIG. The second optimum flying amount distribution D2 is used for writing a first spiral servo pattern described later in self-servo writing, and shifts in accordance with changes in the reference flying amount distribution AVE at a position closer to the reference flying amount distribution AVE than the first flying amount distribution D1.

[0078] Next, in the area from the first position P1 to the second position P2, the main controller 40 sequentially positions the magnetic head 16 to a plurality of positions z9-z0 determined based on the movable distance and the optimal moving speed obtained by the slope learning process, and moves it at the optimal moving speed, and controls the power supplied to the heater H so that the distance between the magnetic head 16 at the moving position z9-z0 and the first spiral surface S1 is in accordance with the second floating amount distribution D2, that is, the first optimal floating amount F1 and each second optimal floating amount F2, while Figure 7 As shown, a plurality of first spiral servo patterns SV1 are written on the first spiral surface S1 of the magnetic disk 12 by the magnetic head 16 (S7).

[0079] In this way, by sequentially positioning the head 16 at a plurality of positions z9 to z0 determined based on the movable distance and the optimal moving speed obtained through slope learning and moving at the optimal moving speed, and setting the spacing between the head 16 and the first spiral surface S1 at each moving position to the first optimal floating amount F1 at position z9 and to the second optimal floating amount F2 corresponding to each moving position at positions z8 to z0, each first spiral servo pattern SV1 can be written onto the first spiral surface S1 of the magnetic disk 12 with high precision without causing the head 16 to contact the first spiral surface S1 of the magnetic disk 12.

[0080] exist Figure 7 In the example of FIG. 8 , eight first spiral servo patterns SV1 are written, but the number of the first spiral servo patterns SV1 is not limited.

[0081] Moreover, in the area from the first position P1 to the second position P2 of the second spiral surface S2 different from the first spiral surface S1 among the multiple recording surfaces S of each magnetic disk 12, the main controller 40 positions the magnetic head 16 opposite to the second spiral surface S2 in sequence to a plurality of positions z9~z0 determined based on the above-mentioned written first spiral servo patterns SV1 while moving at the above-mentioned optimal moving speed, and performs landing processing at each moving position z9~z0, thereby detecting the optimal distance between the magnetic head 16 and the second spiral surface S2 at each moving position as the third optimal floating amount F3 (S8).

[0082] Similarly, in the area from the first position P1 to the second position P2 of the third spiral surface S3 which is different from the first spiral surface S1 and the second spiral surface S2 among the multiple recording surfaces S of each magnetic disk 12, the main controller 40 positions the magnetic head 16 opposite to the third spiral surface S3 in sequence to a plurality of positions z9~z0 determined based on the above-mentioned written first spiral servo patterns SV1 while moving at the above-mentioned optimal moving speed, and performs landing processing at each moving position of the moving positions z9~z0, thereby detecting the optimal distance between the magnetic head 16 and the third spiral surface S3 at each moving position as the fourth optimal floating amount F4 (S9).

[0083] Then, the main controller 40 positions the magnetic head 16 opposite to the second spiral surface S2 in sequence to a plurality of positions z9-z0 determined based on the first spiral servo patterns SV1 written above and moves at the above-mentioned optimal moving speed, and controls the power supplied to the heater H in such a manner that the distance between the magnetic head 16 and the second spiral surface S2 at each moving position becomes the third optimal floating amount F3 corresponding to each moving position, while Figure 8 As shown, a plurality of second spiral servo patterns SV2 are written on the second spiral surface S2 by the magnetic head 16 (S10).

[0084] In this way, by positioning the head 16 based on each written first spiral servo pattern SV1 and moving it at the above-mentioned optimal moving speed, and setting the distance between the head 16 and the second spiral surface S2 at each moving position to the third optimal floating amount F3 corresponding to the moving position, each second spiral servo pattern SV2 can be written into the second spiral surface S2 with high precision through the head 16 without making the head 16 contact with the second spiral surface S2.

[0085] exist Figure 8 In the example shown in FIG. 1 , twelve second spiral servo patterns SV2 are written, but the number of second spiral servo patterns SV2 to be written is not limited.

[0086] Similarly, the main controller 40 positions the magnetic head 16 opposite to the third spiral surface S3 in sequence to a plurality of positions z9-z0 determined based on the first spiral servo patterns SV1 written above and moves at the above-mentioned optimal moving speed, and controls the power supplied to the heater H in such a manner that the distance between the magnetic head 16 and the third spiral surface S3 at each moving position becomes the fourth optimal floating amount F4 corresponding to each moving position, while Fig. 9 As shown, a plurality of third spiral servo patterns SV3 are written on the third spiral surface S3 by the magnetic head 16 (S11).

[0087] In this way, by positioning the head 16 based on each written first spiral servo pattern SV1 and moving it at the above-mentioned optimal moving speed, and setting the distance between the head 16 and the third spiral surface S3 at each moving position to the fourth optimal floating amount F4 corresponding to the moving position, each third spiral servo pattern SV3 can be written into the third spiral surface S3 with high precision through the head 16 without making the head 16 contact with the third spiral surface S3.

[0088] exist Fig. 9 In the example of FIG. 24 3rd spiral servo patterns SV3 are written, but the number of the 3rd spiral servo patterns SV3 to be written is not limited.

[0089] [Landing Process in Step S5]

[0090] Regarding the landing process of step S5 for detecting each second optimal floatation amount F2 in the non-landing area, refer to Fig.11 The flowchart is explained in detail.

[0091] First, the main controller 40 moves the magnetic head 16 to the first position (S501), and in this state controls the heater power supply circuit 34 so that the protrusion of the magnetic head 16 is reduced by a predetermined amount (retraction amount) BO compared to the above-mentioned inner circumference side TD value (S502). Next, the main controller 40 sets a predetermined increase ratio X of the protrusion of the magnetic head 16 under one floating amount detection action (S503), and sets a predetermined upper limit value of the floating amount detection number N (S504). Next, the main controller 40 sets a control flag (S505) for ending the floating amount detection of the step S5 when the magnetic head 16 is held on the ramp loading mechanism RL, that is, when the moving position of the magnetic head 16 based on the processing of the latter step S506 reaches the second position P2.

[0092] In the above step S502, the protrusion of the magnetic head 16 is reduced by a predetermined amount B0 compared to the inner circumference side TD value, but it is sufficient to reduce the protrusion of the magnetic head 16 to a state where the magnetic head 16 does not contact the recording surface S of the magnetic disk 12. For example, the protrusion of the magnetic head 16 may be reduced to approximately 0. In the above step S505, it is also possible to determine whether the magnetic head 16 has moved to the second position P2 based on the resistance value of the HDI sensor as the detection unit 74.

[0093] Next, the main controller 40 moves the magnetic head 16 toward a predetermined position as a floating amount detection object (S506), and determines whether the moving position of the magnetic head 16 reaches the peripheral area of ​​the predetermined position (S507). Figure 6 In the case of the position z5 in the predetermined position, the peripheral area of ​​the predetermined position refers to the area from the middle position between the position z6 and the position z5 to the middle position between the position z5 and the position z4. In the case that the moving position of the magnetic head 16 does not reach the peripheral area of ​​the predetermined position (S507: "No"), the main controller 40 reduces the protrusion amount of the magnetic head 16 by a predetermined amount (S508), returns to the above step S506, and continues to move the magnetic head 16 toward the above predetermined position.

[0094] When the moving position of the magnetic head 16 reaches the peripheral area of ​​the above-mentioned predetermined position (S507: "Yes"), the main controller 40 increases the protrusion amount of the magnetic head 16 by a predetermined amount (S509). Specifically, the main controller 40 increases the protrusion amount of the magnetic head 16 by a value ΔT, which is a value obtained by adding the product value of the number of detection times N of the floating amount at the current time point and the above-mentioned increase ratio X and the second optimal floating amount F2 corresponding to the above-mentioned predetermined position (for example, position z5) in the first optimal floating amount distribution D1, and subtracting the above-mentioned setback amount BO from the added result.

[0095] ΔT=F2+N×X-BO

[0096] For example, when the second optimal floating amount F2 corresponding to the above-mentioned predetermined position in the first optimal floating amount distribution D1 is "115nm", the number of detections N of the floating amount at the current time point is "1", the increase ratio X is "3nm", and the retreat amount BO is "2nm", the increase ΔT in the protrusion amount of the magnetic head 16 is "116nm".

[0097] Next, the main controller 40 determines whether the magnetic head 16 has landed on the recording surface S of the magnetic disk 12 based on the detection result of the detection unit (HDI sensor) 74 ( S510 ).

[0098] When the magnetic head 16 lands on the recording surface S of the magnetic disk 12 (S510: "Yes"), the main controller 40 uses the protrusion amount of the magnetic head 16 at that time point (the calculation result of the operation unit 46d) as a reference value for detecting the second optimal floating amount F2 at the above-mentioned predetermined position and stores it in the memory 47 (S511). Then, the main controller 40 reduces the protrusion amount of the magnetic head 16 at the current time point by a predetermined amount (S512), and returns to the above-mentioned step S506 to move the magnetic head 16 toward the predetermined position as the next floating amount detection object (S506).

[0099] In the judgment of the above step S510, when the magnetic head 16 has not landed on the recording surface S of the magnetic disk 12 (S510: "No"), the main controller 40 increases the number of detections N by "1" (S513) to determine whether the number of detections N has reached the above upper limit value set in the above step S504 (S514).

[0100] When the detection number N has not reached the upper limit (S514: No), the main controller 40 returns to the step S509 and further increases the protrusion amount of the magnetic head 16 by a predetermined amount (S509). The processing after the step S509 is the same as described above.

[0101] When the detection number N reaches the upper limit (S514: Yes), the main controller 40 returns to step S506 and moves the magnetic head 16 toward the next predetermined position for floating amount detection (S506). This movement allows the magnetic head 16 to perform the same landing process at all movement positions.

[0102] In addition, when the number of detection times N reaches the above-mentioned upper limit value (S514: "Yes"), the main controller 40 moves to the above-mentioned step S511, and uses the protrusion amount of the head 16 at the time point when the number of detection times N reaches the above-mentioned upper limit value (the calculation result of the operation unit 46d) as a reference value for detecting the second optimal floating amount F2 at the above-mentioned predetermined position and stores it in the memory 47 (S511).

[0103] The embodiments of the present invention have been described, but the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The above embodiments and their variations are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope of their equivalents.

Claims

1. A magnetic disk device comprising: disk; A magnetic head capable of moving relative to the magnetic disk and capable of adjusting the protrusion toward the magnetic disk and the amount of the protrusion; as well as A controller controls the movement of the magnetic head and the protrusion amount of the magnetic head, the controller, detecting a first optimum floating amount as an optimum distance between a predetermined position of the magnetic disk and the magnetic head, Based on the first optimal floating amount, a first optimal floating amount distribution is estimated as an optimal distance between the magnetic head and the magnetic disk at a plurality of moving positions of the magnetic head, The movable distance and the optimal moving speed of the magnetic head are obtained by controlling the protrusion amount of the magnetic head while moving the magnetic head in such a manner that the distance between the magnetic head and the magnetic disk is distributed according to the first optimal floating amount. While sequentially positioning the moving position of the magnetic head to a plurality of moving positions determined based on the movable distance and the optimal moving speed, respectively detecting a second optimal floating amount as an optimal spacing between the magnetic head and the magnetic disk at each moving position, While the magnetic head is positioned and moved sequentially to a plurality of moving positions determined based on the movable distance and the optimal moving speed, the protrusion amount of the magnetic head is controlled in such a way that the distance between the magnetic head and the magnetic disk at each moving position becomes the first optimal floating amount and each second optimal floating amount, and a plurality of spiral servo patterns are written to the magnetic disk through the magnetic head.

2. The magnetic disk device according to claim 1, The disk is circular, The magnetic head is movable between a first position and a second position of the magnetic disk and includes a heater that generates heat by supplied power, wherein the protrusion amount varies according to the heat generated by the heater. The controller adjusts the protrusion amount of the magnetic head by controlling the power supplied to the heater.

3. The magnetic disk device according to claim 2, the controller, A landing process is performed at the first position of the magnetic disk to control the protrusion amount of the magnetic head in such a manner that the magnetic head contacts the magnetic disk, and the first optimal floating amount is detected based on the protrusion amount of the magnetic head when the magnetic head contacts the magnetic disk.

4. The magnetic disk device according to claim 2, the controller, Based on the first optimal flying amount, optimal distances between the magnetic head and the magnetic disk at a plurality of movement positions of the magnetic head from the first position to the second position are estimated as the first optimal flying amount distribution.

5. The magnetic disk device according to claim 2, the controller, The movable distance and the optimal moving speed are obtained by controlling the protrusion of the magnetic head so that the distance between the magnetic head and the magnetic disk is distributed according to the first optimal floating amount and causing the magnetic head to repeatedly reciprocate between the first position and the second position.

6. The magnetic disk device according to claim 2, the controller, In an area other than the first position in the area from the first position to the second position, the magnetic head is positioned and moved sequentially to a plurality of moving positions determined based on the movable distance and the optimal moving speed, and the landing process is performed at each moving position, thereby detecting each of the second optimal floating amounts.

7. The magnetic disk device according to claim 1, the controller, The magnetic head is positioned and moved sequentially to a plurality of positions determined based on the written spiral servo patterns, and the landing process is performed at each of the moving positions, thereby detecting the optimal spacing between the magnetic head and the magnetic disk at each moving position as a third optimal floating amount, While the magnetic head is positioned and moved sequentially to a plurality of positions determined based on the written spiral servo patterns, the protrusion amount of the magnetic head is controlled in such a way that the distance between the magnetic head and the magnetic disk at each moving position becomes the third optimal floating amount, and a plurality of second spiral servo patterns are written to the magnetic disk through the magnetic head.

8. A method for controlling a magnetic disk device, The magnetic disk device comprises: disk; a magnetic head capable of moving relative to the magnetic disk and capable of protruding toward the magnetic disk and changing the amount of protrusion; and A controller controls the movement of the magnetic head and the protrusion amount of the magnetic head, In the control method of the magnetic disk device, detecting a first optimum floating amount as an optimum distance between a predetermined position of the magnetic disk and the magnetic head, Based on the first optimal floating amount, a first optimal floating amount distribution is estimated as an optimal distance between the magnetic head and the magnetic disk at a plurality of moving positions of the magnetic head, The movable distance and the optimal moving speed of the magnetic head are obtained by controlling the protrusion amount of the magnetic head while moving the magnetic head in such a manner that the distance between the magnetic head and the magnetic disk is distributed according to the first optimal floating amount. While sequentially positioning the moving position of the magnetic head to a plurality of moving positions determined based on the movable distance and the optimal moving speed, respectively detecting a second optimal floating amount as an optimal spacing between the magnetic head and the magnetic disk at each moving position, While the magnetic head is positioned and moved sequentially to a plurality of moving positions determined based on the movable distance and the optimal moving speed, the protrusion amount of the magnetic head is controlled in such a way that the distance between the magnetic head and the magnetic disk at each moving position becomes the first optimal floating amount and each second optimal floating amount, and a plurality of spiral servo patterns are written to the magnetic disk through the magnetic head.

Images