disk device

Abstract

An embodiment provides a magnetic disk device capable of preventing a main magnetic pole portion from contacting a magnetic disk surface. The magnetic disk device includes: a magnetic disk; a magnetic head including a write element for writing data to the magnetic disk and a heating element for adjusting the amount of levitation relative to the magnetic disk; a control unit for controlling the power supplied to the heating element; and a setting unit for setting a heating value based on a measurement result of the recording quality of data written to the magnetic disk. Furthermore, the control unit controls the power supplied to the heating element based on the heating value set in the setting unit.

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2021-099427 (filing date: June 15, 2021), the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] There is known a technique for adjusting the height of components included in a magnetic head by shaving components by grinding or ion beam etching in a subsequent step of manufacturing the magnetic head. Summary of the Invention

[0004] As described above, due to the shaving of the element height, the concavity and convexity of the main magnetic pole portion varies depending on the pole width. Specifically, the wider the pole width, the greater the protrusion height. Therefore, especially in magnetic heads with wide pole widths, the main magnetic pole portion may come into contact with the protrusion on the disk surface. This contact between the main magnetic pole portion and the disk surface can easily cause wear and contamination of the main magnetic pole portion.

[0005] An object of the embodiment is to provide a magnetic disk device that can prevent a main magnetic pole portion from contacting a magnetic disk surface.

[0006] A magnetic disk device according to one embodiment comprises: a magnetic disk; a magnetic head including a write element for writing data to the magnetic disk and a heating element for adjusting a suspension amount relative to the magnetic disk; a control unit for controlling the power supplied to the heating element; and a storage unit for storing a heating value, wherein the heating value is set based on a measurement result of a recording quality of data written to the magnetic disk, and the control unit controls the power supplied to the heating element based on the heating value stored in the storage unit.

[0007] A magnetic disk device according to one embodiment comprises: a magnetic disk; a magnetic head including a write element for writing data to the magnetic disk, a heating element for adjusting a suspension amount relative to the magnetic disk, and an auxiliary element for assisting the writing of data by the write element; a control unit for controlling the power supplied to the heating element; and a storage unit for storing a heating value, the heating value being set based on a resistance value of the auxiliary element, the control unit controlling the power supplied to the heating element based on the heating value stored in the storage unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a block diagram schematically showing an example of the configuration of the magnetic disk device according to the first embodiment.

[0009] Figure 2It is a side view showing an example of a magnetic head and a magnetic disk in a floating state according to this embodiment.

[0010] Figure 3 This is a cross-sectional view schematically showing, in an enlarged manner, a portion of the head portion of the magnetic head and a portion of the magnetic disk according to this embodiment.

[0011] Figure 4 This is a cross-sectional view schematically showing, in an enlarged manner, a recording head tip portion of a magnetic head and a portion of a magnetic disk in a floating state according to this embodiment.

[0012] Figure 5 This is a cross-sectional view schematically showing, in an enlarged manner, a recording head tip portion of a magnetic head and a portion of a magnetic disk in a floating state according to this embodiment.

[0013] Figure 6 This is a diagram showing an example of the protrusion height relative to the magnetic pole width according to this embodiment.

[0014] Figure 7 This is a diagram showing an example of a state before a subsequent step of scraping the main magnetic pole film forming surface of the recording head according to this embodiment.

[0015] Figure 8 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head according to this embodiment is small.

[0016] Figure 9 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head according to this embodiment is large.

[0017] Figure 10 This is a diagram showing an example of the magnitude of the reproduced signal amplitude with respect to the radial direction (off-track direction) according to this embodiment.

[0018] Figure 11 This is a diagram showing an example of the magnitude of heating power relative to the main magnetic pole width according to this embodiment.

[0019] Figure 12 This is a diagram showing an example of the relationship between the BER degradation amount and the write time according to this embodiment.

[0020] Figure 13 This is a diagram showing an example of a state before a subsequent step of scraping the main magnetic pole film forming surface of the recording head according to the second embodiment.

[0021] Figure 14 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head according to this embodiment is small.

[0022] Figure 15 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head according to this embodiment is large.

[0023] Figure 16 This is a diagram showing an example of the relationship between the protrusion height and the resistance value of the auxiliary element according to this embodiment.

[0024] Figure 17 This is a diagram showing an example of the magnitude of the heating power relative to the resistance value of the auxiliary element according to this embodiment.

[0025] Label Description

[0026] 10 Magnetic disk device, 11 Housing, 12 Magnetic disk, 13 ABS, 14 Spindle motor, 15 Slider, 16 Magnetic head, 17 Head, 18 Head actuator, 30 Head amplifier IC, 40 Main controller, 43 Memory, 54 Playback head, 58 Recording head, 60 Main magnetic pole, 62 Return magnetic pole, 64 Guide core, 65 Auxiliary element, 81 Recording current supply circuit, 82 Auxiliary element current supply circuit, 83 Heating voltage supply circuit, 84 Reading voltage supply circuit, 431 Heating setting unit DETAILED DESCRIPTION

[0027] The following describes the embodiments with reference to the accompanying drawings. In addition, the disclosure is merely an example, and the invention is not limited by the contents described in the following embodiments. Deformations that can be easily thought of by those skilled in the art are of course included in the scope of the disclosure. In order to make the description clearer, the dimensions, shapes, etc. of each part are sometimes changed relative to the actual implementation scheme in the drawings and are shown in a schematic manner. In multiple drawings, the same reference numerals are sometimes marked for corresponding elements, and detailed descriptions are omitted.

[0028] (First embodiment)

[0029] Figure 1 This is a block diagram schematically showing an example of the configuration of a hard disk drive (hereinafter referred to as “HDD”) as the magnetic disk device according to the first embodiment. Figure 2 This is a side view showing an example of a magnetic head and a magnetic disk in a floating state. Figure 3 This is a cross-sectional view schematically showing a portion of the magnetic head and a magnetic disk in an enlarged manner.

[0030] like Figure 1As shown, the HDD 10 includes a rectangular housing 11, a magnetic disk 12 serving as a recording medium disposed within the housing 11, a spindle motor 14 that supports and rotates the magnetic disk 12, and a plurality of magnetic heads 16 that write and read data from the magnetic disk 12. The HDD 10 also includes a head actuator 18 that moves the magnetic head 16 to a desired track on the magnetic disk 12 and positions it. The head actuator 18 includes a suspension assembly 20 that movably supports the magnetic head 16 and a voice coil motor (VCM) 22 that rotates the suspension assembly 20.

[0031] The HDD 10 includes a head amplifier IC 30, a main controller 40, and a driver IC 48. The head amplifier IC 30 is, for example, located in the suspension assembly 20 and electrically connected to the magnetic head 16. The main controller 40 and the driver IC 48 are, for example, configured on a control circuit board (not shown) located on the back side of the housing 11. The main controller 40 includes a read / write channel (RDC) 42, a memory 43, a hard disk controller (HDC) 44, and a microprocessor (MPU) 46. The main controller 40 is electrically connected to the head amplifier IC 30 and, via the driver IC 48, to the VCM 22 and the spindle motor 14. The read / write channel (RDC) 42 outputs a recording signal to the magnetic head 16 or decodes a playback signal read from the magnetic head 16. The memory 43 includes a heating setting unit 431. The heating setting unit 431 sets a heating value, which is a voltage value supplied to the heaters 19a and 19b described later. Details on how to set the heating value will be described later. The hard disk controller (HDC) 44 constitutes an interface with a host computer. The HDD 10 can be connected to a host computer (not shown) via the hard disk controller (HDC) 44 .

[0032] The head amplifier IC 30 also includes a recording current supply circuit 81, an auxiliary element current supply circuit 82, a heating voltage supply circuit 83, and a read voltage supply circuit 84. The recording current supply circuit 81 supplies current to the recording head (including the write element) 54. The auxiliary element current supply circuit 82 supplies current to the auxiliary element 65. The heating voltage supply circuit 83 applies voltage to the heaters 19a and 19b (heating elements). The read voltage supply circuit 84 applies voltage to the playback head (including the read element) 54. The recording current supply circuit 81, the auxiliary element current supply circuit 82, the heating voltage supply circuit 83, and the read voltage supply circuit 84 are each electrically connected to the RDC 42. Furthermore, the recording current supply circuit 81, the auxiliary element current supply circuit 82, the heating voltage supply circuit 83, and the read voltage supply circuit 84 are each electrically connected to the recording head 58, the auxiliary element 65, the heaters 19a and 19b, and the playback head 54 of the magnetic head 16.

[0033] like Figure 1 and Figure 2As shown, the magnetic disk 12 is a perpendicular magnetic recording medium having a recording layer that has anisotropy in a direction perpendicular to the disk surface. Specifically, the magnetic disk 12 has a substrate 101 formed into a disk shape with a diameter of approximately 2.5 inches (6.35 cm) and formed of a non-magnetic body. On each surface of the substrate 101, a soft magnetic layer 102 as a base layer, a magnetic recording layer 103 located on the upper portion of the soft magnetic layer 102, and a protective film 104 are sequentially stacked. The magnetic disk 12 and the hub of the spindle motor 14 are coaxially engaged with each other. The magnetic disk 12 is rotated in the direction of arrow B at a predetermined speed by the spindle motor 14.

[0034] The suspension assembly 20 includes a bearing portion 24 fixed to the frame 11 in a freely rotatable manner and a plurality of suspensions 26 extending from the bearing portion 24. Figure 2 As shown, the magnetic head 16 is supported by the extended ends of the suspensions 26. The magnetic head 16 is electrically connected to the head amplifier IC 30 via a wiring member 28 provided in the suspension assembly 20.

[0035] Next, the structure of the magnetic head 16 will be described in detail.

[0036] like Figure 2 and Figure 3 As shown, the magnetic head 16 is a floating type head having a slider 15 formed in a substantially rectangular parallelepiped shape and a head 17 formed at the end portion on the outflow (trailing) side of the slider 15. The slider 15 is formed of, for example, a sintered body of aluminum oxide and titanium carbide (AlTiC), and the head 17 is formed of a multilayer thin film.

[0037] The slider 15 has a rectangular ABS (air bearing surface) 13 facing the surface of the magnetic disk 12. The slider 15 is maintained in a state of floating a predetermined distance from the surface of the magnetic disk 12 by airflow C generated between the disk surface and the ABS 13 as the magnetic disk 12 rotates. The direction of the airflow C coincides with the rotational direction B of the magnetic disk 12. The slider 15 has a leading end 15a located on the inflow side of the airflow C and a trailing end 15b located on the outflow side of the airflow C.

[0038] like Figure 3 As shown, the head 17 is a separate type magnetic head having a playback head 54 and a recording head 58 formed on the trailing end 15b of the slider 15 using a thin film process. To control the amount of levitation during recording and playback of the head 17, a recording heater 19a is disposed behind the recording head 58, and a playback heater 19b is disposed behind the playback head 54.

[0039] The playback head 54 is composed of a playback element (read element) 55 formed of a magnetic film exhibiting a magnetoresistive effect, and an upper shield 56 and a lower shield 57, each of which is provided on the trailing and leading sides of the playback element 55 so as to sandwich the magnetic film 55. The lower ends of the playback element 55, the upper shield 56, and the lower shield 57 are exposed at the ABS 13 of the slider 15. The playback head 54 is connected to the head amplifier IC 30 via electrodes, wiring, and wiring components 28 (not shown), and outputs read data to the head amplifier IC 30.

[0040] The recording head 58 is disposed on the trailing end 15b side of the slider 15 relative to the playback head 54. The recording head 58 includes a main magnetic pole (write element) 60 made of a high-permeability material that generates a recording magnetic field perpendicular to the surface of the magnetic disk 12; a return magnetic pole 62 that serves as a trailing shield (write shield, first shield); and a guide core 64 that serves as a guide shield (second shield). The main magnetic pole 60 and the return magnetic pole 62 form a first magnetic core that forms a magnetic circuit, while the main magnetic pole 60 and the guide core 64 form a second magnetic core that forms a magnetic circuit. The recording head 58 includes a first coil (recording coil) 70 wound around the first magnetic core and a second coil (recording coil) 72 wound around the second magnetic core.

[0041] like Figure 3 As shown, the main magnetic pole 60 extends approximately perpendicular to the surface of the magnetic disk 12. A leading end portion 60a of the main magnetic pole 60 on the magnetic disk 12 side tapers toward the disk surface, and has, for example, a trapezoidal cross-section. The leading end surface of the main magnetic pole 60 is exposed at the ABS 13 of the slider 15. The width of the trailing end surface 60b of the leading end portion 60a approximately corresponds to the width of a track on the magnetic disk 12.

[0042] The return magnetic pole 62, formed of a soft magnetic material, is positioned on the trailing side of the main magnetic pole 60. It 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 generally L-shape and has a first connecting portion 50 connected to the main magnetic pole 60. The first connecting portion 50 is connected to the upper portion of the main magnetic pole 60, i.e., the portion of the main magnetic pole 60 separated from the ABS 13, via a non-conductive material 52.

[0043] The tip end portion 62a of the return magnetic pole 62 is formed in an elongated rectangular shape, with its tip end surface exposed at the ABS 13 of the slider 15. A leading-side end surface 62b of the tip end portion 62a extends along the width direction of the tracks of the magnetic disk 12 and extends approximately perpendicularly to the ABS 13. This leading-side end surface 62b faces the trailing-side end surface 60b of the main magnetic pole 60 in a substantially parallel relationship, with a write gap WG therebetween.

[0044] The first coil 70 is arranged so as to be wound around a magnetic circuit (first magnetic core) including the main magnetic pole 60 and the return magnetic pole 62. The first coil 70 is wound around, for example, the first connecting portion 50. When writing a signal to the magnetic disk 12, a write current flows through the first coil 70, thereby exciting the main magnetic pole 60 and causing a magnetic flux to flow through the main magnetic pole 60.

[0045] The auxiliary element 65 is disposed between the front end 60a of the main magnetic pole 60 and the return magnetic pole 62 within the write gap WG, with a portion thereof exposed at the ABS 13. The auxiliary element 65 is composed of, for example, a high-frequency auxiliary element or a thermal auxiliary element. Furthermore, the lower end surface of the auxiliary element 65 is not limited to being coplanar with the ABS 13; it may also be positioned upward from the ABS 13 in the height direction.

[0046] like Figure 3 As shown, connection terminals 91 and 92 are connected to the main magnetic pole 60 and the return magnetic pole 62, respectively. These connection terminals 91 and 92 are connected to the head amplifier IC 30 via wiring. This forms a current circuit so that current can flow in series from the head amplifier IC 30 through the main magnetic pole 60, the auxiliary element 65, and the return magnetic pole 62. Furthermore, connection terminals 97 and 98 are connected to the recording heater 19a and the reproducing heater 19b, respectively. These connection terminals 97 and 98 are connected to the head amplifier IC 30 via wiring.

[0047] like Figure 3 As shown, a guide core 64 formed of a soft magnetic material is provided on the leading side of the main magnetic pole 60, facing the main magnetic pole 60. The guide core 64 is formed into a roughly L-shaped shape, and the front end portion 64a on the magnetic disk 12 side is formed into an elongated rectangular shape. The front end surface (lower end surface) of the front end portion 64a is exposed at the ABS 13 of the slider 15. The trailing end surface 64b of the front end portion 64a extends along the width direction of the magnetic track of the magnetic disk 12. The trailing end surface 64b faces the leading end surface of the main magnetic pole 60 with a gap therebetween. This gap is covered by a protective insulating film 76, which is a non-magnetic material.

[0048] The guide core 64 has a second connecting portion 68 that engages the back gap between the guide core 64 and the main magnetic pole 60 at a position away from the magnetic disk 12. The second connecting portion 68 is formed of, for example, a soft magnetic material, and forms a magnetic circuit together with the main magnetic pole 60 and the guide core 64. The second coil 72 of the recording head 58 is arranged so as to be wound around the magnetic circuit (second magnetic core) including the main magnetic pole 60 and the guide core 64, and a magnetic field is applied to the magnetic circuit. The second coil 72 is wound around the second connecting portion 68, for example. In addition, a non-conductive or non-magnetic material may be inserted into a portion of the second connecting portion 68.

[0049] The second coil 72 is wound in the opposite direction to the first coil 70. The first coil 70 and the second coil 72 are connected to terminals 95 and 96, respectively, which are connected to the head amplifier IC 30 via wiring. The second coil 72 can also be connected in series with the first coil 70. Alternatively, the first coil 70 and the second coil 72 can each be configured to control the current supply. The current supplied to the first coil 70 and the second coil 72 is controlled by the head amplifier IC 30 and the main controller 40.

[0050] Next, an example of the floating state of the magnetic head 16 will be described.

[0051] Figure 4 and Figure 5 This is a cross-sectional view schematically showing an enlarged view of the recording head tip portion of the magnetic head 16 and a portion of the magnetic disk 12 in a floating state. Figure 6 This is a diagram showing an example of the protrusion height relative to the main magnetic pole width. Figure 7 、 Figure 8 、 Figure 9 1 is a cross-sectional view schematically showing the shape of the recording head main magnetic pole film forming surface of the magnetic head 16 before and after the head subsequent process. More specifically, Figure 7 1 is a diagram showing an example of a state before a subsequent step of scraping the main magnetic pole film forming surface of the recording head. Figure 8 1 is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head is small. Figure 9 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head is large.

[0052] like Figure 4 As shown in FIG. 1 , when the vicinity of the recording head of the magnetic head 16 when it is suspended over the magnetic disk 12 is enlarged, the main magnetic pole portion (the front end portion of the main magnetic pole 60) slightly protrudes relative to other areas. Figure 7 、 Figure 8 、 Figure 9 As shown, when the height of the element is scraped in the subsequent process of the head, the protrusion height W1 is adjusted by ion beam etching (IBE) after the grinding process of the clamp (CMP) etc. so that the element height becomes the floating surface 200. The main magnetic pole portion is required to have a particularly high magnetic permeability, so the content of magnetic metal materials such as Fe and Co, which have a low ion milling rate, is high. Therefore, as Figure 8 、 Figure 9 As shown in FIG. 2 , the floating surface 200 is relatively protruded. Figure 7 、 Figure 8 、 Figure 9 As shown, there is also milling effect from the side of the cross track width direction, so the narrow width of the magnetic pole Figure 8The protruding height W3 of the head shown, Figure 9 The head with a wider magnetic pole width has a larger protruding height W4 (> W3). As a result, Figure 6 As shown, there is a relationship in which the wider the magnetic pole width, that is, the wider the physical width of the magnetic pole, the larger the protrusion height W.

[0053] On the other hand, Figure 4 、 Figure 5 As shown in FIG, in order to prevent the recording performance of the recording head 16 from being reduced due to head-disk interface (HDI) problems such as wear, contamination, and media protrusion (hereinafter also referred to as "HDI failure"), it is necessary to maintain a guaranteed spacing from the front end of the main magnetic pole 60 to the disk surface. Figure 4 As shown in FIG. 1 , the width of the main magnetic pole 60 is narrow and the protruding height W1 is small. Figure 5 For a head with a wide main pole 60 and a large protrusion height W2 (> W1), as shown, the overall levitation of the slider 15 must be compensated (backed off, BO) by an amount equal to the protrusion height × Cos(θ). θ is the pitch angle of the slider 15 during levitation, typically 100 to 150 rad.

[0054] In the present embodiment, the width of the main magnetic pole 60 is measured as follows.

[0055] Figure 10 FIG. 1 is a diagram showing an example of the magnitude of the reproduced signal amplitude relative to the off-track position (radial position). Figure 10 As shown, while the off-track position is changed by the RDC 42, the reproduced signal amplitude of the data written in one track is measured. This allows the MPU 46 to obtain the half-value width (FWHM) of the off-track profile with the same amplitude. Based on this half-value width, i.e., the width of the main magnetic pole 60, the MPU 46 sets the overall flying distance of the slider 15. Specifically, the MPU 46 performs the following settings.

[0056] Figure 11 1 is a diagram showing an example of the magnitude of heating power relative to the width of the main magnetic pole 60 (hereinafter also referred to as “main magnetic pole width”).

[0057] according to Figure 11 It can be seen that there is a proportional relationship between the main magnetic pole width and the heating power. Figure 10The power of heater 19a is changed based on the half-value width measured as shown, thereby adjusting the overall floating amount of slider 15. Specifically, MPU 46 sets a heating value (a voltage value in this embodiment) corresponding to the measured half-value width in heating setting unit 431 of memory 43. This heating value is set so that the wider the half-value width, the lower the power supplied to heater 19a. For example, this heating value is set when HDD 10 is shipped.

[0058] In addition, the wider the main magnetic pole width, the better the bit error rate (BER) and overlap write (OW) characteristics are, and there is a proportional relationship between them and the heating power (omitted from the figure). Therefore, the MPU46 can also be configured to set the heating value to the heating setting unit 431 based on the measured BER or OW. In addition, when there are multiple heaters in the magnetic head 16, the MPU46 can also change the heating value of the heater 19b other than the heater 19a that is closest to the main magnetic pole in the track running direction. Furthermore, the overall suspension amount of the slider 15 can be adjusted by adjusting the power supplied to all heaters, that is, the total power value, and setting it in the heating setting unit 431.

[0059] Figure 12 : is a diagram showing an example of the relationship between the BER degradation amount and the write time. More specifically, Figure 12 The following is an example of fluctuations in the bit error rate (BER) of recorded data when a long write operation is continued using a magnetic head 16 having a wide magnetic pole width and a large protrusion height in the HDD 10 of the present embodiment and another magnetic disk device different from the present embodiment. Here, the other magnetic disk device refers to a magnetic disk device that does not adjust the heating value of the heating setting unit 341 as described above.

[0060] like Figure 12 As shown, in other magnetic disk devices, the suspension amount of the slider 15 is not adjusted according to the main pole width (protrusion height). Therefore, the spacing (Spacing) from the front end of the main pole 60 to the disk surface is relatively smaller than the spacing (Spacing) that can be guaranteed, and reliability is reduced. When reliability is reduced in this way, the bit error rate will deteriorate over a long period of time. On the other hand, in the HDD 10 of this embodiment, the suspension amount of the slider 15 is adjusted according to the main pole width (protrusion height). Therefore, for example, it is possible to suppress the occurrence of errors caused by the above-described Figure 5 The wide main pole width of the magnetic head 16 causes wear and tear caused by reduced spacing. Figure 12It can be confirmed that the HDD 10 of this embodiment can suppress the degradation of the bit error rate even when the write time becomes long. Therefore, the HDD 10 can avoid the main magnetic pole portion from contacting the disk surface of the magnetic disk 12, and can prevent the occurrence of HDI failures such as wear and contamination of the main magnetic pole portion.

[0061] In the first embodiment, the magnetic head 16 includes an auxiliary element, but the present invention is not limited thereto. For example, the technology described above can also be applied to a magnetic disk device in which the magnetic head does not include an auxiliary element.

[0062] In addition, in the first embodiment described above, the case where the magnetic disk 12 and the magnetic head 16 are a set is described as an example, but the HDD 10 may also include multiple sets of magnetic disks 12 and magnetic heads 16. In the case of an HDD 10 configured in this way, when the power value supplied to the magnetic head 16 with the widest half-value width among the multiple magnetic heads 16 is set to the first power value and the power value supplied to the magnetic head 16 with the narrowest half-value width is set to the second power value, the heating value set in the heating value setting unit 431 for each magnetic head 16 may be set so that at least the first power value is smaller than the second power value. Furthermore, the power value supplied to the heaters 19a and 19b of all the magnetic heads 16 may be set to be smaller than the second power value. Thus, even in the case where the HDD 10 includes multiple sets of magnetic disks 12 and magnetic heads 16, the occurrence of HDI failures such as wear and contamination in the main magnetic pole portion can be prevented.

[0063] (Second embodiment)

[0064] While the first embodiment already described a case where the heating value is set based on the width of the main magnetic pole 60, the second embodiment differs in that the heating value is set based on the resistance value of the auxiliary element 65. The following describes in detail the configuration of the heating setting unit 431 for setting the heating value based on the resistance value of the auxiliary element 65. Components identical to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions of these components are omitted.

[0065] Figure 13 、 Figure 14 、 Figure 15 1 is a cross-sectional view schematically showing the shape of the recording head main magnetic pole film forming surface of the magnetic head 16 before and after the head subsequent process. More specifically, Figure 13 1 is a diagram showing an example of a state before a subsequent step of scraping the main magnetic pole film forming surface of the recording head. Figure 14 1 is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head is small. Figure 15 This is a diagram showing an example of a state in which the amount of scraping on the main magnetic pole film forming surface of the recording head is large. Figure 16This is a diagram showing an example of the relationship between the protrusion height and the resistance value of the auxiliary element.

[0066] As already described Figure 5 As shown, when the height of the element is scraped by the head post-process, after the grinding process of the clamp (CMP) etc., the element height is adjusted by ion beam etching (IBE) so as to become the floating surface 200. This is also the same in the second embodiment. Figure 13 As shown in FIG, the main magnetic pole has a shape that widens toward the deep side (upper side in the figure). Therefore, the width of the remaining main magnetic pole changes depending on the amount of scraping, and the protruding height W of the magnetic pole is also affected.

[0067] like Figure 14 As shown in FIG. 1 , when the scraping amount is small, the width of the main magnetic pole becomes narrower and the protruding height W5 becomes smaller. On the other hand, as shown in FIG. Figure 15 As shown in FIG. 1 , when the scraping amount is large, the width of the main magnetic pole 60 becomes wider and the protruding height W6 (> W5) also becomes larger. Thus, the length of the auxiliary element 65 in the height direction (the vertical direction in the figure) will also change according to the scraping amount. As a result, the resistance value of the auxiliary element 65 itself will also change. Figure 14 As shown in FIG. 1 , when the element length of the auxiliary element 65 is long, the resistance value becomes low. Figure 15 As shown in FIG. 1 , when the element length of the auxiliary element 65 is short, the resistance value becomes high. As a result, Figure 16 As shown in FIG. 1 , the higher the resistance value of the auxiliary element, the larger the protrusion height.

[0068] Figure 17 This is a graph showing an example of the magnitude of heating power relative to the resistance value of the auxiliary element. Figure 17 It can be seen that there is a proportional relationship between the auxiliary element resistance value and the heating power. Therefore, the MPU 46 adjusts the overall floating amount of the slider 15 by changing the power of the heater 19a according to the measured auxiliary element resistance value. Specifically, the MPU 46 sets a heating value (a voltage value in this embodiment) corresponding to the measured auxiliary element resistance value in the heating setting unit 431 of the memory 43. This heating value is set so that the higher the resistance value of the auxiliary element 65, the lower the power supplied to the heater 19a.

[0069] In this way, the MPU 46 adjusts the overall floating amount of the slider 15 by changing the power of the heater 19a according to the auxiliary resistance value of the auxiliary element 65, and can also suppress the above-described Figure 5 Therefore, the HDD 10 can avoid the main magnetic pole portion from contacting the disk surface, similarly to the first embodiment, and can prevent HDI failures such as wear and contamination of the main magnetic pole portion.

[0070] In addition, in the second embodiment described above, the case where the magnetic disk 12 and the magnetic head 16 are a set is described as an example, but the HDD 10 may also include multiple sets of magnetic disks 12 and magnetic heads 16. In the case of the HDD 10 configured in this way, when the power value supplied to the magnetic head 16 with the highest resistance value among the multiple magnetic heads 16 is set to the third power value and the power value supplied to the magnetic head 16 with the lowest resistance value is set to the fourth power value, the heating value set in the heating value setting unit 431 for each magnetic head 16 may be set in the heating value setting unit 431 so that at least the third power value is smaller than the fourth power value. Furthermore, the power value supplied to the heaters 19a and 19b of all the magnetic heads 16 may be smaller than the fourth power value. Thus, even in the case where the HDD 10 includes multiple sets of magnetic disks 12 and magnetic heads 16, the occurrence of HDI failures such as wear and contamination in the main magnetic pole portion can be prevented.

[0071] Furthermore, in the above embodiment, the case where the heating value is set in the heating setting unit 431 when the HDD 10 is shipped is described, but the timing of setting the heating value is not limited to this. For example, it is also possible to configure the heating value to be set again according to the environment in which the user uses the HDD 10 after shipping. In this case, Figure 11 The relationship between the main magnetic pole width and the heating power is stored in the memory 43, and the MPU 46 can also be set to measure the relationship between the main magnetic pole width and the heating power. Figure 10 The half-value width is calculated based on the relationship between the off-track position and the reproduced signal amplitude as shown, and a heating value corresponding to the calculated half-value width is set in the heating setting unit 431. In this way, the HDD 10 can set the optimal heating value in the heating setting unit 431 according to the environment after shipping.

[0072] In addition, several embodiments of the present invention have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the scope of the invention. These embodiments and / or their variations are included within the scope and / or spirit of the invention and are included in the invention described in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: disk; a magnetic head including a write element for writing data to the magnetic disk, a read element for reading data written to the magnetic disk, and a heating element for adjusting a floating amount relative to the magnetic disk; a control unit that controls power supplied to the heating element; as well as a setting unit configured to set a heating value based on a measurement result of recording quality of data written to the magnetic disk; The control unit controls the power supplied to the heating element based on the heating value set in the setting unit. The heating value is set in the setting unit based on a half-value width obtained from a measurement result of an off-track curve of a signal amplitude of data read by the read element.

2. The magnetic disk device according to claim 1, The heating value is set in the setting unit such that the wider the half-value width is, the smaller the power supplied to the heating element is.

3. The magnetic disk device according to claim 1, a group comprising a plurality of said magnetic disks and said magnetic heads, When the power value of the power supplied to the magnetic head having the widest half-value width among the plurality of magnetic heads is set to a first power value and the power value of the power supplied to the magnetic head having the narrowest half-value width is set to a second power value, The heating value is set in the setting unit so that the first power value is smaller than the second power value.

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