Disk device

Abstract

According to one embodiment, there is generally provided a disk device capable of suppressing variation of a gap between a recording medium and a head and improving reliability. According to one embodiment, a disk device includes: a disk-shaped recording medium; a magnetic head having a write head, a read head, and a heater for adjusting a gap with the recording medium; a suspension assembly supporting the magnetic head; the micro actuator comprises a piezoelectric element arranged on the suspension assembly; and a controller that sets the driving voltage of the piezoelectric element on the basis of the difference between the landing output when the piezoelectric element is driven and the landing output when the piezoelectric element is not driven.

Description

[0001] This application claims priority to Japanese Patent Application No. 2023-199960, filed on November 27, 2023, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] As a disk device, for example, a magnetic disk device includes: a rotatable disk-shaped recording medium having a magnetic recording layer, and a magnetic head for recording and reproducing data on the magnetic recording layer of the recording medium. The magnetic head is supported by a head actuator so as to be movable in the radial direction of the recording medium. In recent years, a magnetic disk device having a micro actuator for finely adjusting the position of the magnetic head has been proposed.

[0004] In a magnetic disk device, in order to increase the recording density, particularly the linear recording density, it is necessary to set a small gap between the magnetic head and the recording medium. However, when driving the micro actuator, the magnetic head moves not only in the track direction (radial direction) of the recording medium but also slightly in a direction crossing the surface of the recording medium. Therefore, there is a case where the gap between the magnetic head and the recording medium changes and the desired set gap cannot be maintained. Summary of the Invention

[0005] A disk device according to one embodiment includes: a disk-shaped recording medium; a magnetic head having a write head, a read head, and a heater for adjusting a gap with the recording medium; a suspension assembly for supporting the magnetic head; a micro actuator including a piezoelectric element provided on the suspension assembly; and a controller that sets a drive voltage of the piezoelectric element based on a difference between a touchdown output when the piezoelectric element is driven and a touchdown output when the piezoelectric element is not driven.

[0006] According to one embodiment, it is possible to provide a disk device capable of suppressing variations in the gap between the recording medium and the head and achieving an improvement in reliability. Brief Description of the Drawings

[0007] Figure 1 is an exploded perspective view showing the top cover of the hard disk drive (HDD) according to the first embodiment separated.

[0008] Figure 2 is a side view schematically showing a magnetic head, a suspension, and a magnetic disk in the HDD.

[0009] Figure 3 is a perspective view showing one head suspension assembly of the actuator assembly in the HDD.

[0010] Figure 4 It is a top view of the top end portion of the head suspension assembly.

[0011] Figure 5 It is a cross-sectional view showing an enlarged view of the head of the magnetic head in the HDD.

[0012] Figure 6 It is a block diagram schematically showing the configuration of the entire HDD including the controller.

[0013] Figure 7 It is a side view of the head of the magnetic head and the disk schematically showing the floating state of the magnetic head.

[0014] Figure 8 It is a flowchart showing the adjustment operation of the drive voltage of the microactuator provided in the head suspension assembly.

[0015] Figure 9 It is a diagram schematically showing the relationship between the drive voltage and the frequency of the microactuator (differential voltage limit).

[0016] Figure 10 It is a flowchart showing the adjustment operation of the drive voltage of the microactuator in the HDD according to the second embodiment.

[0017] Figure 11 It is a flowchart showing the adjustment operation of the drive voltage of the microactuator in the HDD according to the third embodiment.

[0018] Figure 12 It is a diagram schematically showing the relationship between the drive voltage and the frequency of the microactuator in the third embodiment (differential voltage limit).

[0019] Explanation of Reference Numerals

[0020] 10... housing, 11... disk device, 12... base, 15... slider, 16... magnetic head, 17... head, 30... suspension assembly, 34... suspension, 42... wiring member (flexible member), 44... gimbal portion, 54... read head, 58... write head, 76a... first heater, 76b... second heater, 80... head amplifier IC, 90... main controller Detailed Embodiment

[0021] Hereinafter, with reference to the drawings, the disk device according to the embodiment will be described.

[0022] In addition, the disclosure is merely an example, and technical solutions that those skilled in the art can easily conceive with appropriate changes while maintaining the gist of the invention are of course included in the scope of the present invention. In addition, for the sake of clarity, compared with the actual technical solution, the width, thickness, shape, etc. of each part are sometimes schematically shown in the drawings, but it is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each drawing, sometimes the same reference numerals are assigned to elements that are the same as those already described in the previous drawings, and the detailed description is appropriately omitted or simplified.

[0023] (First Embodiment)

[0024] As an example of a disk device, a hard disk drive (HDD) according to the first embodiment will be described in detail. Figure 1 FIG. is an exploded perspective view showing the top cover of the HDD according to the first embodiment separated. Figure 2 FIG. is a block diagram schematically showing the configuration of the entire HDD including a controller.

[0025] As shown in Figure 1 , the HDD 11 includes a rectangular housing 10. The housing 10 has a rectangular box-shaped base 12 with an open upper surface and a cover (top cover) 14. The base 12 has a rectangular bottom wall 12a and side walls 12b erected along the periphery of the bottom wall 12a, and is integrally formed of, for example, aluminum. The cover 14 is formed of, for example, stainless steel into a rectangular plate shape. The cover 14 is screwed and fixed to the side walls 12b of the base 12 by a plurality of threaded members 13, and hermetically closes the upper opening of the base 12.

[0026] Inside the housing 10, a plurality of, for example, 10 disk-shaped recording media, i.e., disks 18, and a spindle motor 19 that supports and rotates the disks 18 are provided. The spindle motor 19 is disposed on the bottom wall 12a. Each disk 18 has, for example, a substrate formed in a circular plate shape with a diameter of 95 mm (3.5 inches) and magnetic recording layers formed on the upper and lower surfaces of the substrate. The disks 18 are coaxially fitted to the hub of the spindle motor 19 and are further clamped by a clamping spring 20. Thus, the disks 18 are supported in a state where they are located in a position parallel to the bottom wall 12a of the base 12. The plurality of disks 18 are rotated in the direction of arrow B at a predetermined rotational speed by the spindle motor 19. In addition, the number of disks 18 mounted is not limited to 10, and may be 9 or less, or 10 or more and 12 or less.

[0027] Inside the housing 10, there are provided a plurality of heads 16 for recording and reproducing information on the disk 18, and an actuator assembly 22 that supports these heads 16 so as to be movable relative to the disk 18. Further, inside the housing 10, there are provided a voice coil motor (VCM) 24 that rotates and positions the actuator assembly 22, a ramp loading mechanism 25 that holds the head 16 at an unloading position away from the disk 18 when the head 16 moves to the outermost periphery of the disk 18, and a substrate unit (FPC unit) 21 on which electronic components such as a conversion connector are mounted.

[0028] The actuator assembly 22 has an actuator block 29 that is rotatably supported about a support shaft 28, a plurality of arms 32 extending from the actuator block 29, and suspension assemblies 30 extending from each of the arms 32. The support shaft 28 is erected on the bottom wall 12a. The head 16 is supported at the top end of each suspension assembly 30.

[0029] The actuator assembly 22 has a support frame (not shown) extending from the actuator block 29 in a direction opposite to the arms 32, and a voice coil 33 is supported by this support frame. The voice coil 33 is located between a pair of magnetic yokes 37 fixed to the base 12, and together with these magnetic yokes 37 and a magnet fixed to either one of the magnetic yokes, constitutes the VCM 24.

[0030] The FPC unit 21 has a substantially rectangular base portion 21a fixed to the bottom wall 12a, an elongated strip-shaped relay portion 21b extending from one side edge of the base portion 21a, and a joint portion 21c continuously provided at the top end of the relay portion 21b. The base portion 21a, the relay portion 21b, and the joint portion 21c are formed by a flexible printed wiring board (FPC). The joint portion 21c is mounted on the actuator block 29. A head amplifier IC 80 described later is mounted on the joint portion 21c.

[0031] On the outer surface of the bottom wall 12a of the base 12, a printed circuit board 27 is screwed. The base portion 21a of the FPC unit 21 is connected to the printed circuit board 27 via a connector (not shown). The printed circuit board 27 constitutes the controller of the HDD 11. The controller controls the operation of the spindle motor 19 and also controls the operations of the VCM 24 and the head 16 via the substrate unit 21.

[0032] Figure 2 It is a side view schematically showing the floating head and the disk.

[0033] As shown in the figure, the disk 18 has a disk-shaped substrate 101 made of a non-magnetic material such as glass. A base layer 102, a magnetic recording layer 103, and a protective film 104 are sequentially laminated on each surface of the substrate 101. The disk 18 is rotated at a predetermined speed in the direction of arrow B by the spindle motor 19.

[0034] The suspension assembly 30 has a suspension 34, a wiring member (flexible member) 42 mounted on the suspension 34, and a tab 40 protruding from the top end of the suspension 34. The head 16 is supported at the gimbal portion 44 of the flexible member 42. The head 16 is electrically connected to the aforementioned head amplifier IC 80 and FPC unit 21 via the flexible member 42.

[0035] The head 16 is configured as a floating head. The head 16 has a substantially rectangular parallelepiped slider 15 and a head 17. The slider 15 has an inflow end 15a, an outflow end (trailing end) 15b, and a disk facing surface (ABS) 13. The head 17 is formed at an end portion on the outflow end 15b side of the slider 15. The head 17 includes a write head element and a read head element. The head 16 is maintained in a state of floating a predetermined amount from the surface of the disk 18 by an air flow C generated between the disk surface and the slider 15 due to the rotation of the disk 18. The direction of the air flow C is the same as the rotation direction B of the disk 18. Along with the rotation of the disk 18, the head 16 moves relative to the disk 18 in the direction (circumferential direction) A opposite to the rotation direction B.

[0036] Next, an example of the suspension assembly 30 will be described in detail.

[0037] Figure 3 is a perspective view showing one suspension assembly, Figure 4 is a top view of the top end portion of the suspension assembly.

[0038] As Figure 3 shown, each suspension assembly 30 has a suspension 34 extending from an arm 32, and a head 16 is mounted at the top end portion of the suspension 34. In addition, the head 16 and the suspension assembly 30 supporting the same are sometimes collectively referred to as a head suspension assembly.

[0039] The suspension 34 that functions as a support plate has a rectangular base plate 36 made of a metal plate several hundred micrometers thick, and an elongated leaf spring-like load beam 38 made of a metal plate several tens of micrometers thick. The base end portion of the base plate 36 is fixed to the top end portion of the arm 32. The load beam 38 is overlapped and arranged at the top end portion of the base plate 36 through its base end portion and is fixed to the base plate 36 by welding at multiple locations. A rod-shaped tab 40 protrudes at the top end of the load beam 38.

[0040] The suspension assembly 30 has an elongated strip-shaped flexible member (wiring member) 42 for transmitting recording signals, reproduction signals, and drive signals for piezoelectric elements, and a pair of piezoelectric elements (e.g., PZT elements) 50 mounted on the flexible member 42. The flexible member 42 has a tip-side portion 42a disposed on the load beam 38 and the base plate 36, a base-end side portion 42b extending outward from the side edge of the base plate 36 and extending along the side edge of the arm 32 to the base end of the actuator block 29, and a connection end portion (not shown) extending from the base-end side portion 42b. The connection end portion has a plurality of connection pads arranged. These connection pads are electrically joined to the connection terminals provided at the joint portion 21c of the actuator block 29.

[0041] The tip of the flexible member 42 is located above the tip of the load beam 38, forming a gimbal portion 44 that functions as an elastic support portion. The head 16 is placed and fixed on the gimbal portion 44 and is supported by the load beam 38 via the gimbal portion 44. A pair of piezoelectric elements 50 as driving elements are mounted on the gimbal portion 44 and are arranged near the head 16. The pair of piezoelectric elements 50 constitute a microactuator.

[0042] The flexible member 42 has a metal thin plate (metal plate) 46 such as stainless steel as a base, and a strip-shaped laminated member (flexible printed wiring board: FPC) 48 attached or fixed to the metal thin plate 46, forming an elongated laminated plate. The laminated member (FPC) 48 has: a base insulating layer (first insulating layer) mostly fixed to the metal thin plate 46; a conductive layer (wiring pattern) formed on the base insulating layer to constitute a plurality of signal wirings, drive wirings, and a plurality of connection pads; and a covering insulating layer (second insulating layer) covering the conductive layer and laminated on the base insulating layer. In the tip-side portion 42a of the flexible member 42, the metal thin plate 46 is attached to the surfaces of the load beam 38 and the base plate 36, or is spot-welded to the surfaces of the load beam 38 and the base plate 36 through a plurality of welding points.

[0043] As Figure 3 and Figure 4 shown, in the gimbal portion 44, the metal thin plate 46 integrally has: a substantially rectangular tongue portion (support portion) 44a on the tip side, a substantially rectangular base-end portion 44b on the base-end side spaced from the tongue portion 44a by a space, and a pair of elastically deformable outrigger brackets (connection portions) 44c connecting the base-end portion 44b and the tongue portion 44a respectively.

[0044] The tongue portion 44a is formed to have a size and shape capable of placing the head 16, for example, formed in a substantially rectangular shape. The tongue portion 44a is arranged such that the central axis in its width direction coincides with the central axis C of the suspension 34 (refer to Figure 4 ).

[0045] The approximate center of the tongue portion 44a abuts against a dimple (convex portion) 47 protruding from the top end portion of the load beam 38. The tongue portion 44a can be displaced in various directions with the dimple 47 as a fulcrum by elastic deformation of a pair of outstretched brackets 44c. Thus, the tongue portion 44a and the magnetic head 16 mounted on the tongue portion 44a can flexibly follow surface variations of the magnetic disk 18 to be displaced in the roll direction or the pitch direction, maintaining a minute gap between the surface of the magnetic disk 18 and the magnetic head 16.

[0046] In the gimbal portion 44, the laminated member 48 of the flexible member 42 is disposed on the metal plate 46 and extends from the base end portion 44b along the central axis C1 above the tongue portion 44a. That is, the laminated member 48 has a base end portion 48a attached to the base end portion 44b, a top end portion 48b attached to the tongue portion 44a, and a pair of strip-shaped bridge portions 48c extending in a bifurcated shape from the base end portion 48a to the top end portion 48b.

[0047] At the top end portion 48b, a plurality of connection pads (electrode pads) 45 are arranged in the width direction. In addition, a plurality of connection pads (electrode pads) 51 for connecting the piezoelectric elements 50 are provided at the base end portion 48a. The laminated member 48 has a plurality of signal wirings W1 extending from the connection pads 45 around both side edge portions of the top end portion 48b to the base end portion 48a side and a plurality of drive wirings W2 extending from the connection pads 51 to the base end portion 48a side. These signal wirings W1 and drive wirings W2 extend over substantially the entire length of the laminated member 48 and are connected to the connection pads 43 of the connection end portion 42c.

[0048] The magnetic head 16 is fixed to the tongue portion 44a by an adhesive. The magnetic head 16 is arranged such that the central axis in the length direction coincides with the central axis C of the suspension 34. In addition, the approximate center of the magnetic head 16 is located above the dimple 47. Connection pads PT of the magnetic head 16 described later are electrically connected to the plurality of connection pads 45 at the top end portion 48b by a conductive adhesive such as solder or silver paste. Thus, the magnetic head 16 is connected to the signal wiring W1 of the laminated member 48 via the connection pads 45.

[0049] As Figure 4 shown, a pair of piezoelectric elements 50 use, for example, rectangular plate-shaped thin film piezoelectric elements (PZT elements). The piezoelectric elements 50 are arranged such that their length direction (expansion and contraction direction) is parallel to the central axis C of the suspension 34. The two piezoelectric elements 50 are arranged on both sides in the width direction Y of the magnetic head 16 and are arranged parallel to each other. Both end portions in the length direction of each piezoelectric element 50 are mounted on and electrically connected to the connection pads 51 at the base end portion 48a. Thus, the piezoelectric elements 50 are connected to the drive wiring W2 of the laminated member 48 via the connection pads 51.

[0050] The piezoelectric element 50 is not limited to a PZT element, and other piezoelectric elements may also be used. Furthermore, the drive element is not limited to a piezoelectric element, and other drive elements capable of expanding and contracting by current application may also be used. In addition, the microactuator is not limited to a pair of drive elements, and may also be constituted by a single drive element. Furthermore, the piezoelectric element is not limited to being disposed near the magnetic head 16, and may also be disposed near the boundary portion between the base plate and the load beam, or may be disposed near both the magnetic head 16 and the boundary portion between the base plate and the load beam.

[0051] By applying a voltage (drive signal) to the piezoelectric element 50, the piezoelectric element 50 expands and contracts along its longitudinal direction (the direction parallel to the central axis C of the suspension). By driving the two piezoelectric elements 50 in directions opposite to each other in terms of the expansion and contraction directions, the pair of bridge portions 48c also slide in opposite directions to each other. As Figure 4 shown, the bridge portion 48c causes the tongue portion 44a of the gimbal portion 44 and the magnetic head 16 to swing around the pit 47 in the direction of arrow D. In this way, the magnetic head 16 can be slightly displaced by the expansion and contraction operation of the piezoelectric element 50. In addition, the swing direction D of the magnetic head 16 corresponds to the seek direction (track crossing direction) of the magnetic head 16 on the magnetic disk 18.

[0052] Next, an example of the configuration of the magnetic head 16 will be described in detail.

[0053] Figure 5 is a cross-sectional view showing an enlarged view of the head 17 of the magnetic head 16 and the magnetic disk 18.

[0054] As Figure 5 shown, the head 17 of the magnetic head 16 has a reproduction head (read head) 54 and a recording head (write head) 58 formed by a thin film process at the trailing end 15b of the slider 15, and is formed as a separated type magnetic head. The read head 54 and the write head 58 are covered with a non-magnetic protective insulating film 53 except for the portions exposed at the ABS 13 of the slider 15. The protective insulating film 53 forms the outer shape of the head 17. Furthermore, the head 17 has a first thermal actuator for controlling the protrusion amount of the write head 58 and a second thermal actuator for controlling the protrusion amount of the read head 54. The first thermal actuator has, for example, a heater 76a buried in the protective insulating film 53 and located near the write head 58. The second thermal actuator has, for example, a heater 76b buried in the protective insulating film 53 and located near the read head 54.

[0055] The length direction of the recording track formed on the perpendicular magnetic recording layer 103 of the magnetic disk 18 is defined as the downtrack direction DT, and the width direction of the recording track orthogonal to the length direction is defined as the cross track direction.

[0056] The read head 54 includes a magnetoresistive effect element 55, and a first magnetic shielding film 56 and a second magnetic shielding film 57 that are disposed on the leading side (inflow side) and trailing side (outflow side) of the magnetoresistive effect element 55 in the track following direction DT with the magnetoresistive effect element 55 therebetween. The magnetoresistive effect element 55, the first magnetic shielding film 56, and the second magnetic shielding film 57 extend substantially perpendicular to the ABS 13. The lower ends (top ends) of the magnetoresistive effect element 55, the first magnetic shielding film 56, and the second magnetic shielding film 57 protrude slightly from the ABS 13.

[0057] The write head 58 is disposed on the trailing end 15b side of the slider 15 with respect to the read head 54. The write head 58 includes: a main magnetic pole 60 that generates a recording magnetic field in a direction perpendicular to the surface of the magnetic disk 18; a trailing shield 62 that is disposed on the trailing side of the main magnetic pole 60 and faces the main magnetic pole 60 across a write gap; a leading shield 64 that faces the leading side of the main magnetic pole 60; and a pair of side shields (not shown) that are integrally formed with the trailing shield 62. The main magnetic pole 60 and the trailing shield 62 constitute a first magnetic core that forms a magnetic circuit, and the main magnetic pole 60 and the leading shield 64 constitute a second magnetic core that forms a magnetic circuit. The write head 58 has a first recording coil 70 wound around the first magnetic core and a second recording coil 72 wound around the second magnetic core.

[0058] The main magnetic pole 60 is formed of a soft magnetic material having a high magnetic permeability and a high saturation magnetic flux density, and extends substantially perpendicular to the ABS 13. The top end portion 60a of the main magnetic pole 60 on the ABS 13 side tapers more and more toward the top toward the ABS 13, and is formed in a columnar shape that is narrower in width than other portions. The top end portion 60a of the main magnetic pole 60 protrudes slightly from the ABS 13 of the slider 15.

[0059] The trailing shield 62 is formed of a soft magnetic material and is provided to efficiently close the magnetic circuit through the soft magnetic layer 102 of the magnetic disk 18 directly below the main magnetic pole 60. The trailing shield 62 is formed in a substantially L shape, and its top end portion 62a is formed in an elongated rectangular shape. The top end portion 62a of the trailing shield 62 protrudes slightly from the ABS 13 of the slider 15.

[0060] The trailing shield 62 has a first connection portion 63 connected to the main magnetic pole 60. The first connection portion 63 is magnetically connected to the upper portion of the main magnetic pole 60, that is, the portion of the main magnetic pole 60 that is separated from the ABS 13, via a non-conductor 65. The first recording coil 70 is wound around the first connection portion 63 in the first magnetic core, for example. When writing a signal to the magnetic disk 18, by passing a recording current through the first recording coil 70, the first recording coil 70 excites the main magnetic pole 60 to cause magnetic flux to flow through the main magnetic pole 60.

[0061] A leading shield 64 formed of a soft magnetic material is disposed opposite to a main magnetic pole 60 on the leading side of the main magnetic pole 60. The leading shield 64 is formed in a substantially L shape, and a top end portion 64a on the ABS13 side is formed in an elongated rectangular shape. The top end portion 64a slightly protrudes from the ABS13 of the slider 15.

[0062] In addition, the leading shield 64 has a second connecting portion 68 joined to the main magnetic pole 60 at a position away from the ABS13. The second connecting portion 68 is formed of a soft magnetic material, for example, 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 ABS13 via a non-conductive body 69. Thus, the second connecting portion 68 forms a magnetic circuit together with the main magnetic pole 60 and the leading shield 64. A second recording coil 72 of the write head 58 is wound around the second connecting portion 68, for example, and a magnetic field is applied to the magnetic circuit.

[0063] A plurality of connection pads PT are provided at the trailing end 15b of the slider 15. The first recording coil 70 and the second recording coil 72 are respectively connected to the connection pads PT via wirings, and further connected to the head amplifier IC80 via a flexible member 42. When writing a signal to the magnetic disk 18, by supplying a recording current to the first recording coil 70 and the second recording coil 72, the main magnetic pole 60 is excited and magnetic flux flows through the main magnetic pole 60.

[0064] Similarly, the magnetoresistive effect element 55 of the read head 54 is connected to the connection pads PT via a wiring (not shown), and further connected to the head amplifier IC80 via a flexible member 42. A signal read by the read head 54 is amplified by the head amplifier IC80 and sent to the main controller.

[0065] The first heater 76a and the second heater 76b are respectively connected to the connection pads PT via wirings, and further connected to the head amplifier IC80 via a flexible member 42. By applying driving power from the head amplifier IC80 to the first heater 76a and the second heater 76b, the heater and the periphery of the heater can be heated, and the write head 58 or the read head 54 can be bulged toward the magnetic disk 18 side.

[0066] Figure 6FIG. 0 is a block diagram schematically showing the configuration of the entire HDD 11 including the main controller. As shown in the figure, the HDD 11 includes a controller that includes a head amplifier IC 80 for driving the head 16, a main controller 90, and a driver IC 52. The head amplifier IC 80 is provided, for example, in the actuator assembly 22 and is electrically connected to the head 16 via the flexure 42. The head amplifier IC 80 includes: a recording current supply circuit (recording current supply unit) 82 that supplies a recording current to the recording coils 70 and 72 of the head 16; a heater power supply circuit 84 that supplies driving power to the thermal actuators (heaters 76a and 76b) of the head 16; an amplifier 86 that amplifies the signal read by the head 16; and a PZT power supply circuit 88 that supplies a driving voltage to the piezoelectric element (micro actuator) 50, etc.

[0067] The main controller 90 and the driver IC 52 are configured to be provided on the aforementioned printed circuit board 27 on the back side of the housing 10. The main controller 90 includes an R / W channel 92, a hard disk controller (HDC) 94, a microprocessor (MPU) 96, a memory 97, etc. The main controller 90 is electrically connected to the head 16 via the head amplifier IC 80. The main controller 90 is electrically connected to the VCM 24 and the spindle motor 19 via the driver IC 52. The HDC 94 can be connected to the host 95.

[0068] In the memory 97 of the main controller 90, various measured values, heater power setting values, etc. described later are stored. In the main controller 90, for example, the MPU 96 includes a write control unit 96a that controls the write head, a read control unit 96b that controls the read head, a heater control unit 96c that controls the power supplied to the thermal actuator, and a PZT control unit 96d that controls the power (voltage) supplied to the piezoelectric element 50, etc.

[0069] Next, the operation of measuring and adjusting the spacing (gap) (sometimes referred to as the flying height or backoff amount (BO)) between the head 16 and the surface of the disk 18 in the HDD 11 configured as described above will be described. The HDD 11 performs the gap measurement and adjustment operation at the time of factory shipment, at regular intervals, or each time a recording operation is performed.

[0070] Figure 7 FIG. 13 is a diagram schematically showing an example of the flying state of the head 16. In the figure, BO represents the backoff amount of the head 16, SP represents the desired gap of the recording head 58. θ represents the tilt angle of the ABS 13 with respect to the surface of the disk 18, and r represents the distance between the trailing end of the slider and the main magnetic pole 60.

[0071] During normal recording operation, the main controller 90 causes the slave heater power supply circuit 84 to supply heater power of a predetermined power (wattage) value to the first heater 76a and the second heater 76b, heating the first heater 76a and the second heater 76b. Thereby, the write head 58 and the surrounding portions are heated and bulge out toward the surface side of the magnetic disk 18, setting the gap (retraction amount) BO between the write head 58 and the disk surface to a predetermined value. By increasing the supply power value to the heater, the protrusion amount increases and the gap decreases. By decreasing the supply power value to the heater, the protrusion amount decreases and the gap increases. The heater control unit 96c and the heater power supply circuit 84 control the heating level (supply power value) of the first heater 76a and the second heater 76b so that the gap BO becomes a desired value. The magnetic head 16 performs a recording operation in a state where the predetermined gap BO is set.

[0072] Figure 8 It is a flowchart showing an example of a measurement and adjustment operation.

[0073] As shown in the figure, for example, in the measurement and adjustment operation of the gap BO at the time of HDD shipment, first, the main controller 90 selects an arbitrary suspension assembly 30 and its magnetic head N (magnetic head 16). The PZT control unit 96d of the main controller 90 causes the slave PZT power supply circuit 88 to supply the maximum drive voltage Vmax (V) of the micro actuator to a pair of piezoelectric elements 50 of the selected suspension assembly 30 to perform expansion and contraction driving. In a state where the piezoelectric element 50 is driven, the main controller 90 supplies heater power from the heater power supply circuit 84 to the first heater 76a and the second heater 76b to bulge the magnetic head 16 toward the surface side of the magnetic disk 18. The main controller 90 increases the heater power value until the lower end corner of the magnetic head 16 contacts (lands) on the surface of the magnetic disk 18, measures the heater power value at the time of landing, and stores it as the landing output (TDP) MA1 (mW) in the memory 97 (ST1).

[0074] Next, the main controller 90 reduces the heater power value to a normal value, returns the magnetic head 16 to the normal floating amount BO, and further stops the power supply to the piezoelectric element 50, that is, returns the piezoelectric element 50 to the non - energized state. In a state where the piezoelectric element 50 is not driven, the main controller 90 supplies heater power from the heater power supply circuit 84 to the first heater 76a and the second heater 76b to bulge the magnetic head 16 toward the surface side of the magnetic disk 18. The main controller 90 increases the heater power value until the lower end corner of the magnetic head 16 contacts (lands) on the surface of the magnetic disk 18, measures the heater power value at the time of landing, and stores it as the landing output (TDP) MA2 (mW) in the memory 97 (ST2).

[0075] The main controller 90 calculates the difference ΔMA = (MA2 - MA1) (mW) between the landing output MA1 (mW) when the microactuator is driven and the landing output MA2 when the microactuator is not driven, and stores it in the memory 97 (ST3). ΔMA corresponds to the change in the floating amount when the piezoelectric element 50 is driven at the maximum driving voltage.

[0076] Generally, the floating amount (retraction amount OB) of the head 16 is determined by the accumulation of variation factors. The variation in the floating amount caused by the driving of the piezoelectric element also becomes one of the variation factors. Here, the target value of the variation in the floating amount caused by the driving of the piezoelectric element is defined as BO. MA . When the output difference ΔMA is greater than the target value BO MA , the risk of contact between the disk 18 and the slider of the head 16 increases. In addition, the target value BO MA is pre-stored in the memory 97.

[0077] Then, according to this embodiment, the main controller 90 compares the calculated output difference ΔMA with the target value BO MA (ST4). When ΔMA is greater than the target value BO MA , the ratio of BO MA to ΔMA (BO MA / ΔMA) is multiplied by the maximum driving voltage Vmax to calculate the correction value Vma (ST5). The main controller 90 sets the obtained correction value Vma as the maximum driving voltage Vmax of the piezoelectric element 50 and stores it in the memory 97. In addition, when ΔMA is less than the target value BO MA , the main controller 90 does not change the maximum driving voltage Vmax, but stores it in the memory 97 as the predetermined maximum driving voltage Vmax (ST7).

[0078] During the recording operation, the main controller 90 drives the piezoelectric element 50 within the range of the maximum driving voltage Vmax set as described above. As a result, the variation in the floating amount (BO) of the head 16 when the microactuator (piezoelectric element) is driven becomes below the target value BO MA . Therefore, even when the microactuator is driven, it is possible to suppress the variation in the floating amount BO of the head 16 and reduce the risk of contact between the disk and the head slider.

[0079] Regarding the HDD according to the first embodiment configured as above, by adjusting the driving voltage of the microactuator based on the difference between the landing output when the microactuator is driven and the landing output when the microactuator is not driven, the variation amount of the floating amount of the head when the microactuator is driven can be suppressed to be below a predetermined target value. Thereby, the risk of contact between the disk and the head slider can be reduced, and the reliability of the HDD can be improved. Furthermore, the floating amount BO of the head 16, that is, the gap between the surface of the disk and the head 16, can be set to the minimum value, and the recording density of the HDD can be improved.

[0080] In summary, according to the first embodiment, a disk device that can suppress the variation of the gap between the recording medium and the head and improve the reliability can be provided.

[0081] In addition, in the first embodiment, for an HDD having a plurality of suspension assemblies and a plurality of heads, it can also be configured to measure and adjust the maximum driving voltage of the aforementioned microactuator for each suspension assembly.

[0082] Next, the HDD according to other embodiments will be described. In the other embodiments described below, the same parts as those in the above first embodiment are denoted by the same reference numerals, and their detailed descriptions are omitted or simplified, and the detailed description will be centered on the parts different from the first embodiment.

[0083] (Second Embodiment)

[0084] Figure 9 It is a schematic diagram for setting the differential voltage limit of the driving voltage of the microactuator in the HDD according to the second embodiment.

[0085] In the second embodiment, the differential voltage limit is applied to the control of the driving voltage of the microactuator (piezoelectric element 50). In addition, in this embodiment, the differential voltage limit is defined as: the higher the frequency of the voltage input to the piezoelectric element 50, the more the control of the voltage difference for each servo frame is suppressed.

[0086] As Figure 9 shown, in the second embodiment, the driving voltage at the sampling frequency is used as the set voltage Vs. In this case, the driving voltage is limited to Vs by the sampling frequency.

[0087] Figure 10 It is a flowchart showing an example of the measurement and adjustment operations of the driving voltage in the second embodiment.

[0088] As shown in the figure, in the second embodiment, similar to the aforementioned first embodiment, the main controller 90 measures the landing output MA1 (ST1) when the micro actuator is driven, measures the landing output MA2 (ST2) when the micro actuator is not driven, and calculates the difference ΔMA (ST3). Next, the main controller 90 compares the calculated output difference ΔMA with the target value BO MA (ST4). When ΔMA is greater than the target value BO MA , when the driving voltage frequency of the piezoelectric element 50 at landing is set to f1, based on the differential voltage limit shown in Figure 9 , the voltage Vf1 corresponding to the frequency f1 is set. The main controller 90 calculates the correction value Vsf1 by multiplying the ratio of BO MA to ΔMA (BO MA / ΔMA) by the voltage Vf1 (ST5). The main controller 90 sets the obtained correction value Vsf1 as the driving voltage Vf1 at the frequency f1 and stores it in the memory 97 (ST6). In addition, when the frequency range at landing is set to f1 to f2, the main controller 90 may also perform the same processing as described above at the frequency fm between f1 and f2.

[0089] On the other hand, in ST4, when ΔMA is less than the target value BO MA , the main controller 90 does not change the driving voltage Vf1 and stores it in the memory 97 as the predetermined driving voltage Vf1 (ST7).

[0090] During the recording operation, the main controller 90 drives the piezoelectric element 50 within the range of the driving voltage Vf1 set as described above. As a result, the variation in the floating amount (BO) of the magnetic head 16 when the micro actuator (piezoelectric element) is driven becomes the target value BO MA or less. Therefore, even when the micro actuator is driven, it is possible to suppress the variation in the floating amount BO of the magnetic head 16 and reduce the risk of contact between the disk and the head slider.

[0091] In summary, according to the second embodiment, it is possible to provide a disk device that can suppress the variation in the gap between the recording medium and the head and improve reliability.

[0092] (Third Embodiment)

[0093] Figure 11 is a flowchart showing an example of the driving voltage measurement and adjustment operation in the third embodiment. Figure 12 is a schematic diagram for setting the differential voltage limit of the driving voltage of the micro actuator in the third embodiment.

[0094] As Figure 11As shown, in the third embodiment, similar to the aforementioned first embodiment, the main controller 90 measures the landing output MA1 during the driving of the micro actuator (ST1), measures the landing output MA2 when the micro actuator is not driven (ST2), and calculates the difference ΔMA (ST3). Next, the main controller 90 compares the calculated output difference ΔMA with the target value BO MA (ST4). When ΔMA is greater than the target value BO MA , when the driving voltage frequency of the piezoelectric element 50 during landing is set to f1, based on the differential voltage limit shown in Figure 12 , the voltage Vs corresponding to the driving voltage frequency of the piezoelectric element 50 during landing is set. The main controller 90 calculates the correction value Vsma by multiplying the ratio of BO MA to ΔMA (BO MA / ΔMA) by the voltage Vs (ST5). The main controller 90 sets the obtained correction value Vsma as the set value Vs of the differential voltage limit at the sampling frequency and stores it in the memory 97 (ST6).

[0095] On the other hand, in ST4, when ΔMA is less than the target value BO MA , the main controller 90 does not change the driving voltage Vs and stores it as the set value Vs of the driving voltage in the memory 97 (ST7).

[0096] During the recording operation, the main controller 90 drives the piezoelectric element 50 within the range of the driving voltage Vs set as described above. In this case, as shown by the dotted line in Figure 12 , the frequency characteristics of the differential voltage limit are suppressed according to the correction value Vsma, so that the variation in the floating amount (BO) of the head 16 during the driving of the micro actuator (piezoelectric element) becomes the target value BO MA or less. Therefore, even when the micro actuator is driven, the variation in the floating amount BO of the head 16 can be suppressed, reducing the risk of contact between the disk and the head slider.

[0097] In summary, according to the third embodiment, a disk device capable of suppressing the variation in the gap between the recording medium and the head and improving reliability can be provided.

[0098] In addition, in either the second embodiment or the third embodiment, for an HDD having a plurality of suspension assemblies and a plurality of heads, the configuration may be such that the measurement and adjustment of the driving voltage of the aforementioned micro actuator are performed for each suspension assembly (each head). By setting the driving voltage for each head, even if there are deviations (fluctuations) in the head separation variations, the variations can be made below a certain level, enabling more accurate retraction control.

[0099] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their variations are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalents.

[0100] For example, the materials, shapes, sizes, etc. of the elements constituting the head of the magnetic head can be changed as needed. In a disk device, the number of disks and magnetic heads can be increased or decreased as needed, and various selections can be made for the size of the disks.

Claims

1. A disk device comprising: a disc-shaped recording medium; a magnetic head having a write head, a read head, and a heater for adjusting a gap with the recording medium; A suspension assembly, supporting the magnetic head; A microactuator, comprising a piezoelectric element disposed on the suspension assembly; as well as The controller sets the driving voltage of the piezoelectric element according to the difference between the landing output when the piezoelectric element is driven and the landing output when the piezoelectric element is not driven.

2. The disk device according to claim 1, The landing output when the piezoelectric element is driven is MA1, the landing output when the piezoelectric element is not driven is MA2, the difference is ΔMA, and the target value of the gap change is BO. MA , when the maximum driving voltage of the piezoelectric element is set to Vmax, When the difference ΔMA is greater than the target value BO MA In the case of MA A correction value Vma is obtained by multiplying the maximum driving voltage Vmax by the ratio of the difference ΔMA, and the calculated correction value Vma is set as the maximum driving voltage Vmax of the piezoelectric element.

3. The disk device according to claim 1, The disk device includes a plurality of suspension assemblies each having the magnetic head and the piezoelectric element. The controller sets the driving voltage of the piezoelectric element for each suspension assembly according to the difference between the landing output when the piezoelectric element is driven and the landing output when the piezoelectric element is not driven.

4. A disk device comprising: a disc-shaped recording medium; a magnetic head having a write head, a read head, and a heater for adjusting a gap with the recording medium; A suspension assembly, supporting the magnetic head; A microactuator, comprising a piezoelectric element disposed on the suspension assembly; as well as The controller sets a differential voltage limit of the piezoelectric element so that the change in the gap caused by driving the piezoelectric element becomes less than a target value based on the difference between the landing output when the piezoelectric element is driven and the landing output when the piezoelectric element is not driven.

5. The disk device according to claim 4, The disk device includes a plurality of suspension assemblies each having the magnetic head and the piezoelectric element. For each suspension component, the controller sets a differential voltage limit of the piezoelectric element so that the change in the gap caused by driving the piezoelectric element is less than a target value based on the difference between the landing output when the piezoelectric element is driven and the landing output when the piezoelectric element is not driven.

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