1. Field
The present technique relates to head sliders arranged in storage medium drives such as hard disk drives (HDDs), and more particularly to a head slider having a heater embedded in a nonmagnetic film corresponding to a head element.
2. Description of the Related Art
In a head slider, for example, a nonmagnetic film made of Al2O3 (alumina) is laminated on a slider body made of Al2O3—Tic (alumina-titanium carbide, AlTic). The nonmagnetic film has a head element and a heater embedded therein. The surface of the nonmagnetic film is covered with, for example, a protection film made of diamond like carbon (DLC). The head element is thus covered with the protection film.
The heater applies heat to a thin-film coil pattern provided in the head element. The thin-film coil pattern linearly expands accordingly, and hence, a read gap and a write gap of the head element can come close to a magnetic disk. A flying height of the head element is determined on the basis of a bulging amount of the thin-film coil pattern.
To determine the bulging amount, zero calibration is performed. Reference documents are Japanese Laid-open Patent Publication No. 2003-203321, Japanese translation of PCT international application Publication No. 2002-500798, Japanese Laid-open Patent Publication No. 2002-117509, Japanese Laid-open Patent Publication No. 05-20635, and US2005/0057841.
In the zero calibration process, the bulging amount of the thin-film coil pattern is gradually increased. When the protection film comes into contact with the magnetic disk, the bulging amount of the thin-film coil pattern is obtained. A most suitable bulging amount for reading and writing can be determined on the basis of the obtained bulging amount.
During the zero calibration process, the protection film comes into contact with the magnetic disk. As the contact is repeated, the protection film may be subjected to wear. The wear may reduce the thickness of the protection film. As a result, the protection film can no longer effectively protect the head element. For example, the head element may be subjected to corrosion under a high temperature and humidity environment. The characteristics of the head element may be deteriorated.
The present technique is provided in light of the situations described above, and an object of the technique is to provide a head slider and a storage medium drive capable of preventing a head element from being damaged in this manner.
The disclosed technique was produced for solving the problems due to the foregoing related techniques. A head slider arranged opposite to a storage medium has a slider body, an insulating nonmagnetic layer laminated on a trailing edge of the slider body, and a rail formed on a medium-opposing surface of the slider body and extending from the slider body to the nonmagnetic film. A head element is embedded in the nonmagnetic film, a front edge of the head element being exposed at a top surface of the rail. A heater is embedded in the nonmagnetic film, the heater causing the head element to bulge at the top surface of the rail. A protection film is laminated on the top surface of the rail, and a protrusion is configured to protrude from a surface of the protection film and come closer to the storage medium than the top surface of the protection film when the head element bulges.
The housing space houses at least a magnetic disk 14 as a storage medium. The magnetic disk 14 is mounted to a rotating shaft of a spindle motor 15. The spindle motor 15 can rotate the magnetic disk 14 at a high speed of, for example, 5400, 7200, 10000, or 15000 rpm. The magnetic disk 14 is a perpendicular recording magnetic storage medium.
The housing space further houses a carriage 16. The carriage 16 has a carriage block 17. The carriage block 17 is rotatably coupled to a vertically extending spindle 18. The carriage block 17 has a plurality of carriage arms 19 horizontally extending from the spindle 18. The carriage block 17 may be molded, for example, by extrusion using aluminum.
A head suspension 21 is attached to the tip end of each of the carriage arms 19. The head suspension 21 extends from the tip end of the carriage arm 19 to the front. A flexure is bonded to the tip end of the head suspension 21. The flexure has a gimbal spring. As the gimbal spring works, a flying head slider 22 can change its posture relative to the head suspension 21. Though described below, an electromagnetic conversion element (head element) is mounted to the flying head slider 22.
When an airflow is generated at the surface of the magnetic disk 14 due to the rotation of the magnetic disk 14, a positive pressure, or a buoyant force, and a negative pressure act on the flying head slider 22 because of the effect of the airflow. The buoyant force and the negative pressure are balanced with a pressing force of the head suspension 21, whereby the flying head slider 22 can continuously fly with a relatively high rigidity during the rotation of the magnetic disk 14.
If the carriage 16 rotates around the spindle 18 while the flying head slider 22 flies, the flying head slider 22 can move along a radial line of the magnetic disk 14. As a result, the electromagnetic conversion element mounted on the flying head slider 22 can move across a data zone between the innermost recording track and the outermost recording track. The electromagnetic conversion element on the flying head slider 22 can be positioned at a desired recording track.
The carriage block 17 is connected to a power source such as a voice coil motor (VCM) 23. As the VCM 23 works, the carriage block 17 can rotate around the spindle 18. The carriage arm 19 and the head suspension 21 can swing in accordance with the rotation of the carriage block 17.
As shown in
For reading of magnetic information, sense current is supplied from the head IC 27 to the read head element of the electromagnetic conversion element. The read head element employs, for example, a current-perpendicular-to-plane (CPP) read head element. For writing of magnetic information, write current is supplied from the head IC 27 to the write head element of the electromagnetic conversion element. The write head element employs, for example, a single pole head element. The current value of the sense current is determined to a given value. The current is supplied to the head IC 27 from a small circuit board 29 disposed in the housing space, and a printed circuit board (not shown) attached to the back side of a bottom plate of the base 13.
A medium-opposing surface, or an air bearing surface 34 of the flying head slider 22 faces the magnetic disk 14. The air bearing surface 34 has a flat base surface 35 serving as a reference plane. As the magnetic disk 14 rotates, an airflow 36 acts on the air bearing surface 34 from the front edge to the rear edge of the slider body 31.
A front rail 37 is formed at the air bearing surface 34. The front rail 37 projects from the base surface 35 near the upstream side, or the leading side of the airflow 36. The front rail 37 extends in a slider width direction along the leading edge of the base surface 35. Also, a rear rail 38 is formed at the air bearing surface 34. The rear rail 38 projects from the base surface 35 near the downstream side, or the trailing side of the airflow 36. The rear rail 38 is arranged at the center in the slider width direction. The rear rail 38 extends from the slider body 31 to the element-containing film 32.
Further, a pair of auxiliary rear rails 39 are formed at the air bearing surface 34. The auxiliary rear rails 39 project from the base surface 35 near the trailing side. The auxiliary rear rails 39 are arranged respectively along left and right edges of the base surface 35. Hence, the auxiliary rear rails 39 are arranged with an interval provided therebetween in the slider width direction. The rear rail 38 is arranged between the auxiliary rear rails 39.
The front rail 37, the rear rail 38, and the auxiliary rear rails 39 have air bearing surfaces (ABS) 41, 42, and 43 at their top surfaces. Leading edges of the air bearing surfaces 41, 42, and 43 are connected to the top surfaces of the rails 37, 38, and 39 through steps 44, 45, and 46. The air bearing surface 34 receives the airflow 36 generated due to the rotation of the magnetic disk 14. At this time, relatively large positive pressures, or buoyant forces are generated at the air bearing surfaces 41, 42, and 43 because of the effects of the steps 44, 45, and 46. Also, a large negative pressure is generated at the rear, or the back of the front rail 37. Accordingly, the flying posture of the flying head slider 22 is determined on the basis of the balance between the buoyant forces and the negative pressure. The configuration of the flying head slider 22 is not limited to the one described above.
On the air bearing surfaces 41, 42, and 43, for example, protection films (not shown) are laminated. The top surface of the rear rail 38 is covered with the protection film at the trailing edge of the air bearing surface 42. As shown in
Also referring to
The CPP read head element 47 has a magnetoresistive film 59 such as a spin-valve film or a tunnel junction film. The magnetoresistive film 59 is interposed between an upper electrode 61 and a lower electrode 62. The upper and lower electrodes 61 and 62 are respectively in contact with the upper and lower boundaries of the magnetoresistive film 59 at the front edge where the upper and lower electrodes 61 and 62 are exposed at the surface of the slider body 31. The upper and lower electrodes 61 and 62 supply the magnetoresistive film 59 with sense current. The upper and lower electrodes 61 and 62 may have a conductivity, and a soft magnetic property. If the upper and lower electrodes 61 and 62 are made of a conductive and soft magnetic material such as a permalloy (Ni—Fe alloy), the upper and lower electrodes 61 and 62 can also serve as upper and lower shield layers of the CPP read head element 47. In this way, the upper and lower electrodes 62 define a read gap.
The single pole head element 48 has a main pole 64 and an auxiliary pole 65 both being exposed at the air bearing surface 42. The main pole 64 and the auxiliary pole 65 may be made of a conductive soft magnetic material such as a permalloy. The main pole 64 and the auxiliary pole 65 together define a magnetic core of the single pole head element 48. For example, a nonmagnetic gap layer 66 made of Al2O3 is interposed between the main pole 64 and the auxiliary pole 65. When a magnetic field is produced by the thin-film coil pattern (described below), with the effect of the nonmagnetic gap layer 66, the magnetic flux leaks from the main pole 64 to the auxiliary pole 65. The leaking magnetic flux forms a gap magnetic field, or a recording magnetic field. In this way, the main pole 64 and the auxiliary pole 65 define a write gap.
Also referring to
A thin-film coil pattern 71 is disposed on the nonmagnetic gap layer 66. The thin-film coil pattern 71 extends along a plane in a spiral manner. The thin-film coil pattern 71 is embedded in an insulating layer 72 above the nonmagnetic gap layer 66. The above-described auxiliary pole 65 is formed on the surface of the insulating layer 72. The auxiliary pole 65 is magnetically coupled to the main pole 64 at the center of the thin-film coil pattern 71. When current is supplied to the thin-film coil pattern 71, magnetic flux circulates through the main pole 64 and the auxiliary pole 65.
The element-containing film 32 has a heater arranged therein corresponding to the electromagnetic conversion element 33. The heater is, for example, a heating wire 73 embedded in the insulating layer 72. The heating wire 73 extends along a plane. As shown in
As shown in
The current supply circuit 82 is connected to the single pole head element 48. Write current is supplied from the current supply circuit 82 to the single pole head element 48. The single pole head element 48 generates a magnetic field on the basis of the supplied write current.
The power supply circuit 83 is connected to the heating wire 73. Electric power is supplied from the power supply circuit 83 to the heating wire 73. The heating wire 73 generates heat in accordance with the supplied electric power. The temperature of the heating wire 73 is determined by the electric energy. That is, the bulging amount of the bulge 74 can be controlled on the basis of the electric energy.
The head IC 27 is connected to a control circuit (hard disk controller, HDC) 84. The control circuit 84 instructs the head IC 27 to supply the sense current, write current, and electric power. In addition, the control circuit 84 detects the voltage of the sense current. Before the detection of the voltage, the preamplifier circuit 81 amplifies the voltage of the sense current.
The control circuit 84 determines the binary data on the basis of the output of the preamplifier circuit 81. Further, the control circuit 84 detects “a fluctuation” of the voltage value on the basis of the output of the preamplifier circuit 81. For example, when the protection pads 49 come into contact with the magnetic disk 14 on account of the formation of the bulge 74, the flying head slider 22 may be slightly vibrated. At this time, “a fluctuation” is generated in the voltage value of the sense current. The control circuit 84 detects “the fluctuation”.
The control circuit 84 controls the operations of the preamplifier circuit 81, the current supply circuit 82, and the power supply circuit 83 corresponding to a predetermined software program. Such a software program may be stored in, for example, a memory 85. With the software program, zero calibration (described later) is performed. Data required for the zero calibration may be also stored in the memory 85. The software program and data may be transmitted to the memory 85 from other storage medium. The control circuit 84 and the memory 85 may be mounted on the circuit board 29.
In this hard disk drive 11, the bulging amount of the single pole head element 48 is determined before reading or writing of magnetic information. To determine the bulging amount, zero calibration is performed. During the zero calibration, the bulging amount of the bulge 74 is measured when the protection pads 49 come into contact with the magnetic disk 14. A bulging amount of the bulge 74 for reading or writing of information is determined on the basis of the measured bulging amount in the contact state. The bulging amount of the bulge 74 for reading or writing of information is determined, whereby the single pole head element (electromagnetic conversion element) 48 can fly over the surface of the magnetic disk 14 at a predetermined flying height. The zero calibration may be performed, for example, every time when the hard disk drive 11 is activated.
To perform the zero calibration, the control circuit 84 executes the predetermined software program. When the software program is executed, the control circuit 84 performs initial setting of the hard disk drive 11. In the initial setting, the control circuit 84 instructs the spindle motor 15 to drive. The magnetic disk 14 rotates at a predetermined rotation speed accordingly. Also, the control circuit 84 instructs the VCM 23 to drive. The carriage 16 swings around the spindle 18 accordingly. As a result, the flying head slider 22 faces the surface of the magnetic disk 14. The flying head slider 22 flies over the magnetic disk 14 at a predetermined flying height. Further, the control circuit 84 supplies the head IC 27 with current. The control circuit 84 monitors the output of the preamplifier circuit 81. That is, the control circuit 84 observes the voltage value of the sense current. At this time, the power supply circuit 83 suspends the supplement of the electric power.
When the initial setting is completed, the control circuit 84 supplies the power supply circuit 83 with a command signal. The control circuit 84 increases the bulging amount of the bulge 74 by a given increment. In response to the reception of the command signal, the power supply circuit 83 supplies the heating wire 73 with electric power of an electric energy corresponding to the increased bulging amount. The given increment may be, for example, 0.1 nm. The electric energy may be determined in advance on the basis of the coefficient of linear expansion of the single pole head element 48. When the bulging amount of the bulge 74 is increased, the control circuit 84 determines “contact” between the protection pads 49 and the magnetic disk 14. For the judgment, the control circuit 84 observes the presence of “a fluctuation” appearing in the voltage value of the sense current.
The control circuit 84 increases the bulging amount of the bulge 74 by the given increment until the control circuit 84 observes “the fluctuation”. The protection pads 49 always come close to the magnetic disk 14 as compared with the top of the bulge 74, in accordance with the bulging amount of the bulge 74. Finally, as shown in
In the above-described hard disk drive 11, the protection pads 49 come into contact with the magnetic disk 14 when the bulging amount of the bulge 74 is determined. The top surface of the protection film 51 can be prevented from coming into contact with the magnetic disk 14 in the area between the protection pads 49. Thus, wear of the protection film 51 can be reliably prevented at the top of the bulge 74. The protection film 51 can effectively protect the electromagnetic conversion element 33. Thus, corrosion of the electromagnetic conversion element 33 can be reliably prevented.
As shown in
As shown in
With the above-described flying head slider 22, the protection pads 49 do not have to be disposed parallel to the trailing edge of the slider body 31. For example, one of the protection pads 49 may be disposed near the leading edge, and the other one may be disposed near the trailing edge. Otherwise, the protection pads 49 may be replaced with a protruding wall continuously surrounding the periphery of the bulge 74. In this case, the protruding wall may have a notch. The shape of the protection pad 49 is not limited to those described above. The shape of the protection pad 49 may be modified as desired.
With the above-described configuration of the present technique, the protrusions come close to the storage medium as compared with the top surface of the protection film when the head element bulges. Accordingly, the top surface of the protection film can be reliably prevented from coming into contact with the storage medium when the protrusions come into contact with the storage medium. Wear of the protection film can be prevented at the front edge of the head element. Damage of the head element can be thus effectively prevented.
In addition, since the pair of protrusions are provided on the surface of the protection film, and the protrusions are disposed parallel to the trailing edge of the slider body with the predetermined interval provided between the protrusions, the pair of protrusions can come into contact with the storage medium stably.
Further, since the nonmagnetic film has the first region with the first coefficient of linear expansion, and the second regions with the second coefficient of linear expansion which is larger than the first coefficient of linear expansion, the second regions being provided on both sides of the head element, the width of the bulge of the head element is increased by the effects of the heater and the second regions. The interval between the protection pads is increased. Thus, the protection pads can come into contact with the storage medium stably.
With the present technique, the head slider and the storage medium drive capable of preventing the head element from being damaged can be provided.
Number | Date | Country | Kind |
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2007-034502 | Feb 2007 | JP | national |