Patent Application
20220415349
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-107222, filed Jun. 29, 2021, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a magnetic disk device.
As a magnetic recording and reproducing device, for example, a magnetic disk device comprises a rotatable disk-shaped recording medium, a magnetic head for recording/reproducing data on a magnetic recording layer of the recording medium and a head actuator that positions the magnetic head at a desired radial position on the recording medium. The magnetic head includes a slider, a reproducing element and a recording element provided on the slider. In order to improve the recording density, a magnetic head having an assist function, for example, a heater, have been proposed. Here, by heating the magnetic head with the heater, the reproducing element and/or recording element are expanded to the recording medium side, so as to control the distance between the reproducing and/or recording element and the surface of the recording medium.
However, it takes a certain amount of time until the temperature of the magnetic head, especially the recording element section and the entire head, to saturate. For example, a certain amount of time is required from the time when the heater is started to be energized for the recording element to expand and protrude to the desired position. On the other hand, it is required for the magnetic disk drives to record data at high speed by shortening the time from the start to the end of writing. In order to shorten the time to start writing, it is necessary to shorten the above-described protruding time. Therefore, in order to achieve high-speed processing in a magnetic disk device, the protruding time needs to be shortened.
Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, a magnetic disk device comprises a rotatable magnetic disk and a magnetic head including a recording head portion that records data on the magnetic disk. The recording head portion comprises a main magnetic pole that applies a recording magnetic field to the magnetic disk, a first yoke provided on a first side of the main magnetic pole and a second yoke provided on a second side of the main magnetic pole, which is opposite to the first side. The magnetic head includes a first heater provided to oppose a side of the first yoke, opposite to the main magnetic pole and a second heater provided to oppose a side of the second yoke, opposite from the main magnetic pole.
Embodiments will be described hereinafter with reference to the accompanying drawings. The disclosure is merely an example, and proper changes within the spirit of the invention, which are easily conceivable by a skilled person, are included in the scope of the invention as a matter of course. In addition, in some cases, in order to make the description clearer, the widths, thicknesses, shapes, etc., of the respective parts are schematically illustrated in the drawings, compared to the actual modes. However, the schematic illustration is merely an example, and adds no restrictions to the interpretation of the invention. Besides, in the specification and drawings, the same or similar elements as or to those described in connection with preceding drawings or those exhibiting similar functions are denoted by like reference numerals, and a detailed description thereof is omitted unless otherwise necessary.
As an example of the magnetic disk devices, a hard disk drive (HDD) according to the first embodiment will be described in detail.
As shown in
The HDD 10 comprises a head amplifier IC 30 that drives the magnetic heads 16, a main controller 40 and a driver IC 48. The head amplifier IC 30 is, for example, provided on the carriage assembly 20 and is electrically connected to the magnetic heads 16. The head amplifier IC 30 comprises a recording current supply circuit 32 that supplies a recording current to the recording coils of the magnetic heads 16, a heater voltage supply circuit 34 that supplies drive power to a thermal actuator (to be referred to as “heater” hereinafter) of the magnetic heads 16, which will be described later and an amplifier (not shown) that amplifies the signal read by the magnetic heads 16, and the like.
The main controller 40 and the driver IC 48 are, for example, installed on a control circuit board (not shown) provided on a rear surface side of the housing 11. The main controller 40 comprises an R/W channel 42, a hard disk controller (HDC) 44, a microprocessor (MPU) 46, a memory 47 and the like. The main controller 40 is electrically connected to the magnetic head 16 via the head amplifier IC 30. The main controller 40 is electrically connected to the VCM 22 and the spindle motor 14 via the driver IC 48. Note that the HOC 44 is connectable to a host computer 45.
In the memory 47 of the main controller 40, a heater power setting table (not shown) and the like, are stored. In the main controller 40, for example, the MPU 46 adjusts the power supplied to the heater based on the heater power setting table.
As shown in
As shown in
The magnetic heads 16 each comprise a substantially rectangular disk-facing surface (air bearing surface (ABS)) 13 that opposes the surface of the respective magnetic disk 12. The Magnetic head 16 is maintained in a state where it flies a predetermined amount above the surface of the respective magnetic disk 12 by air flow generated between the disk surface and the ABS 13 by the rotation of the magnetic disk 12. The direction of the air flow coincides with the rotational direction B of the magnetic disk 12. As the magnetic disk 12 rotates, the magnetic head 16 travels in a direction opposite to the disk rotation direction B with respect to the magnetic disk 12.
As shown in
The longitudinal direction of the recording track formed on the perpendicular magnetic recording layer 103 of the magnetic disk 12 is defined as a down-track direction DT, and the width direction of the recording track orthogonal to the longitudinal direction is defined as a cross-track, direction.
The reproduction head 54 includes a magnetoresistive element 55 and a first magnetic shield film 56 and a second magnetic shield film 57 disposed respectively on a leading side and a trailing side of the magnetoresistive effect element 55 in the down track direction DT so as to interpose the magnetoresistive effect element 55 therebetween. The magnetoresistive element 55, the first and second magnetic shielding films 56 and 57 are extend substantially perpendicularly to the ABS 13.
The recording head 58 is provided on a trailing side (a first side) of the slider 15 with respect to the reproduction head 54. The opposite side of the trailing side is a leading side (a second side). The recording head 58 includes a main magnetic pole 60 that generates a recording magnetic field in the perpendicular direction to the surface of the magnetic disk 12, a trailing shield (a first yoke) 6 provided on the trailing side of the main magnetic pole 60 and opposing the main magnetic pole 60 with a wright gap. 62, a leading shield (a second yoke) 64 opposing the leading side of the main magnetic pole 60, and a pair of side shields (not shown) formed to be integrated with the leading shield and provided on respective sides both sides of the main magnetic pole 60 along the cross track direction. The main magnetic pole 60 and the trailing shield 62 constitute a first magnetic core which forms a magnetic path, and the main magnetic pole 60 and the leading shield 64 constitutes a second magnetic core that forms a magnetic path. The recording head 58 includes a first recording coil 70 wound on the first magnetic core and a second recording coil 70 wound on the second magnetic core.
The main magnetic pole 60 is formed from a soft magnetic material having high magnetic permeability and high saturation flux density, and extends substantially perpendicular to the ABS 13. A distal end portion 60a of the main magnetic pole 60 on the ABS 13 side is tapered down toward the ABS 13 and formed into a columnar shape having a width less relative to those of other parts.
The trailing shield 62 is formed of a soft magnetic material and is provided to efficiently close the magnetic path via the soft magnetic layer 102 of the magnetic disk 12 directly under the main magnetic pole 60. The trailing shield 62 is formed into a substantially L-shape, and a distal end portion thereof 62a is formed into a slender rectangular shape.
The trailing shield 62 includes a first connection portion 50 connected to the main magnetic pole 60. The first connection portion 50 is magnetically connected to an upper portion of the main magnetic pole 60, that is, a portion of the main magnetic pole 60, which is away from the ABS 13, via a non-conductive material 52. The first recording coil 70 is wound around, for example, the first connection portion 50 in the first magnetic core. When writing a signal to the magnetic disk 12, a recording current is applied to the first recording coil 70, and thus the first recording coil 70 excites the main magnetic pole 60 to make magnetic flux flow to the main magnetic pole 60.
The leading shield 64, formed of a soft magnetic material, is provided on the leading side of the main magnetic pole 60, to oppose the main magnetic pole 60. The leading shield 64 is formed into substantially an L-shape, and the leading portion 64a on the ABS 13 side formed into a slender rectangular shape.
Further, the leading shield 64 includes a second connection portion 68 bonded to the main magnetic pole 60 at a position separated from the ABS 13. The second connection 68 is formed, for example, of a soft magnetic material, and is magnetically connected to the upper portion of the main magnetic pole 60, that is, the portion of the main magnetic pole 60, which is away from the ABS 13, via the non-conductive material 69. Thus, the second connection 68 forms a magnetic circuit together with the main magnetic pole 60 and the leading shield 64. The second recording coil 72 of the recording head 58 is, for example, wound around the second connection 68. The second recording coil 72 of the recording head 58, for example, is arranged to be wound around the second connection 63 so as to apply a magnetic field to the magnetic circuit.
The configurations of the heaters will now described.
As shown in
As shown in
With this structure, the heater 76c includes a plurality of vertical portion each extending perpendicular to the ABS 13, and the vertical portions are arranged in the track width direction so as to be spaced apart from each other. The vertical portions located at both ends in the track width direction extend upward beyond the upper end of the trailing shield 62, and the upper ends of the vertical portions are substantially alignment with the upper end of the recording head 58. Those vertical portions in the middle section along the track width direction are located to oppose the trailing shield 62, extend upward beyond the upper end of the trailing shield 62, and the upper ends of the vertical portions are substantially alignment with the upper end of the recording head 58. The lower side of the heater 76c is not exposed to the ABS 13, but extends to the vicinity of the ABS 13.
Note that the heater (second heater) 76d has a shape similar to that of the heater 76c.
Next, an example of connection between the heater 76b, heater 76c and heater 76d, and the heater voltage supply circuit 34 of the head amplifier IC 30 will be described with reference to
In the example of the connection shown in
In the example of the connection shown in
In the example of the connection shown in
When recording data on a magnetic disk, the indicated voltage is applied to the heaters 76c and 76d based on the instructions of the MPU 46, and the recording head 58 is thermally expanded by the heat of the heaters 76c and 76d. In more detail, by applying voltage to the heaters 76c and 76d, the temperatures of the trailing shield 62, the leading shield 64, the first recording coil 70 and the second recording coil 72 are increased, to cause thermal expansion. Thus, the ABS 13 of the head portion 17 also expands toward the surface of the magnetic disk 12, and thus the flying amount with respect to the surface of the magnetic disk, that is, the gap between the ABS 13 of the head 17 and the surface of the magnetic disk 12 can be adjusted.
The head portion of the magnetic head according to a comparative example will now be described.
As shown in
As shown in
Therefore, as compared to the temperature distribution of the comparative example shown in
As shown in
As indicated by the characteristic line g4 in
As shown in the characteristic lines g4 and g5, the protruding time at which the gap D1 stabilizes is T3 for the magnetic head of this embodiment, whereas it is T4 (>T3) for the magnetic head of the comparative example, That is, it can be understood that the magnetic head of this embodiment reaches the gap D1 faster than the magnetic head of the comparative example. Since data recording is carried out after the gap is stabilized, the magnetic head of this embodiment is able to record data faster than the magnetic head of the comparative example.
According to the HDD 10 of the first embodiment, which is configured as described above, the recording head 5 can be efficiently heated by the heaters 76c and 76d located in the vicinity of the recording head 58. With this structure, in the HDD 10, the time required for the magnetic head to protrude can be shortened, making it possible to start recording earlier. Thus, the performance of the data recording process of the HDD 10 can be improved.
Next, the magnetic head of an HDD of another embodiment will be described. In this embodiment, which will be provided below, the same parts as those in the first embodiment described above are denoted by the same reference symbols as those of the first embodiment, and the detailed description thereof may be omitted or simplified.
As shown in
As shown in
As shown in
As described above, the heaters 76c and heater 76d may be configured according to the sizes of the trailing shield 62 and the leading shield 64. With the above-described configuration, the recording head 58 can be thermally expanded more efficiently.
In the second embodiment as well, advantageous effect similar to those of the first embodiment described above can be obtained.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
The recording head of the magnetic head of each of the embodiments can be applied to a type which does not comprise a leading shield and/or side shields. The material, shape, size, etc., of the elements which constitute the head portion of the magnetic head can be changed as needed. In the magnetic disk device, the number of magnetic disks and the number of magnetic heads can be increased or decreased as needed, and the size of the magnetic disks can be selected in various ways. The shapes of the first and second heaters are not limited to those of the embodiments described above, and can be changed in various ways as needed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-107222 | Jun 2021 | JP | national |
