The present invention relates to a hard disk drive (HDD) with thermally assisted magnetic heads and, more particularly, to a head stack assembly (HSA) with a light shielding structure to shield undesired laser light emitted by a laser diode module to prevent light coupling generating between adjacent laser diode modules.
HDDs are common information storage devices. With improvements in recording density of magnetic HDDs, there has been a demand for improving the performance of magnetic heads and magnetic recording media. In a magnetic hard disk drive, a magnetic head is mounted on a slider that flies above the surface of a magnetic recording medium.
Recently, a technology so-called thermal assisted magnetic recording has been proposed, and a thermal assisted magnetic head also has been put to use. The technology uses a magnetic recording medium having high coercivity. When writing data, a write magnetic field and heat are applied almost simultaneously to the area of the magnetic recording medium where to write data, so that the area rises in temperature and drops in coercivity for data writing. The area where data is written subsequently falls in temperature and rises in coercivity to increase the thermal stability of magnetization.
Commonly, the heat source comes from the thermal assisted magnetic head.
With this arrangement of the laser diode module 130, the laser diode module 130 is vertically mounted on the slider substrate 110, the laser light is emitted perpendicular to top and bottom surfaces of the laser diode 131. As shown, the laser lights with two directions includes a downward laser light 191 emitted from the top surface of the laser diode 131 to the write element (the direction facing to a rotating disk is so-called downward, herein), and an upward laser light 192 emitted from the bottom surface of the laser diode 131 (the direction against a rotating disk is so-called upward), so as to reach a photodiode 133 embedded in the mounting base 132 thereby detecting the laser light.
However, in the HSA level, the upward laser light 192 becomes an undesired light for adjacent laser diode which may affect the stability of the interfered laser diode. Many HGAs with a thermal assisted magnetic head are stacked in a HSA, every two thermal assisted magnetic heads and every two HGAs facing the same rotating disks are so-called a thermal assisted magnetic head pair, a HGA pair, here.
Accordingly, it is desired to provide improved HSA with light shielding structure, and disk drive unit to overcome the above-mentioned drawbacks.
One aspect of the present invention is to provide a head stack assembly with a light shielding structure, to shield undesired laser light to interfere adjacent laser diode module of adjacent head gimbal assembly, thereby improving thermal stability of the thermal assisted magnetic head.
Another aspect of the present invention is to provide a disk drive unit including a head stack assembly with a light shielding structure, to shield undesired laser light to interfere adjacent laser diode module of adjacent head gimbal assembly, thereby improving thermal stability of the thermal assisted magnetic head.
To achieve above objectives, a head stack assembly of the present invention includes a mounting base, a plurality of drive arms connected with the mounting base, and multiple pairs of head gimbal assemblies connected with the drive arms. Each head gimbal assembly includes a thermal assisted magnetic head, the thermal assisted magnetic head has an air bearing surface, a bottom surface opposite to the air bearing surface, and a laser diode module mounted on the bottom surface and adapted to emit a downward laser light to a write element of the thermal assisted magnetic head and an upward laser light, wherein a light shielding structure is provided to prevent the upward laser light emitting to other laser diode modules to generate light coupling.
As a preferred embodiment, the light shielding structure is a tilting structure arranged for the laser diode module.
Preferably, the laser diode module includes a mounting substrate and a laser diode unit mounted on the mounting substrate.
More preferably, the laser diode unit and the mounting substrate have a back surface respectively, the laser diode unit and the mounting substrate are tilted toward a trailing edge of the thermal assisted magnetic head, with a tilt angle is formed between the back surfaces and a vertical line perpendicular to the bottom surface of the thermal assisted magnetic head.
Optionally, the tilt angle is in a range of 0.5° to 1.5°.
As another embodiment, the mounting substrate is mounted on the bottom surface of the thermal assisted magnetic head vertically, and the laser diode unit is mounted on the bottom surface of the thermal assisted magnetic head slantwise, with a tilt angle is formed between a top surface of the laser diode unit and the bottom surface of the thermal assisted magnetic head.
Preferably, a photodiode unit is embedded in the mounting substrate and connected with the laser diode unit to detect the upward laser light.
As another embodiment, the light shielding structure includes a plurality of shielding plate connected with the mounting base.
Preferably, two thermal assisted magnetic heads of each pair of the head gimbal assembly are faced to a same rotating disk, and the shielding plate is set between two adjacent thermal assisted magnetic heads in adjacent pair of the head gimbal assembly.
More preferably, the shielding plate is made of conductive and nontransparent material.
A disk drive unit of the present invention includes a head stack assembly having a mounting base, a plurality of drive arms connected with the mounting base, and multiple pairs of head gimbal assemblies connected with the drive arms. Each head gimbal assembly includes a thermal assisted magnetic head having an air bearing surface, a bottom surface opposite to the air bearing surface, and a laser diode module mounted on the bottom surface and adapted to emit a downward laser light to a write element of the thermal assisted magnetic head and an upward laser light, wherein a light shielding structure is provided to prevent the upward laser light emitting to other laser diode modules to generate laser light coupling.
In comparison with the prior art, as the present invention provides a light shielding structure to prevent the upward laser light emitting to other laser diode modules to generate light coupling, thus the upward laser light may not received by a photodiode of the adjacent laser diode module, and less light coupling is generated, therefore the detection result of the adjacent photodiode is accurate, and in turns, the laser power of the adjacent thermal assisted magnetic head is easy to control, finally thermal stability of the adjacent thermal assisted magnetic head is improved.
Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.
The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:
a is a partial exploded perspective view of a conventional thermal assisted magnetic head;
b is a partial side view of a head stack assembly with the thermal assisted magnetic heads;
c is a partial view of the head stack assembly of
a is a perspective view of a head stack assembly with thermal assisted magnetic heads according to one embodiment of the present invention;
b is a simplified and partial side view of the head stack assembly shown in
Various preferred embodiments of the invention will now be described with reference to the figures, wherein like reference numerals designate similar parts throughout the various views. As indicated above, the invention is directed to a head stack assembly (HSA) with a light shielding structure, and a disk drive unit with the same, which can shield undesired laser light emitted by a laser diode module to prevent light coupling between adjacent laser diode modules, so as to improve thermal stability of the thermal assisted magnetic head.
Referring to
As shown, the slider substrate 231 has an ABS 231a, a bottom surface 231b opposite to the ABS 231a, a trailing edge 231c, a leading edge 231d opposite to the trailing edge 231c, and two side surfaces (not labeled). The ABS 231a facing to the disk is processed so as to provide an appropriate flying height, and a read/write element 340 is embedded in the trailing edge 231c. The trailing edge 231c has multiple bonding pads (not shown) to connect with a suspension 290 of the HGA 201. Specifically, the laser diode module 232 is mounted on the bottom surface 231b, for emitting laser light to facilitate writing.
Concretely, as shown in
During writing operations, the thermally assisted magnetic head 230 aerodynamically flies above the surface of the rotating disks 203 with a predetermined flying height. When writing data, signal current is conducted through the coils 348 and flux is induced into the first and second magnetic poles 344, 346, which causes flux to fringe across the pole tips at the ABS 231a. This flux magnetizes circular tracks on the rotating disk 203 during a write operation. Meanwhile, laser light is generated from the laser diode unit 233, and propagated through the waveguide 354 and guided to the plasmon unit 356. Then, the near-field generating surface 3561 of the plasmon unit 356 will generate near-field light which may be propagated to the ABS 231a. The generated near-field light reaches the surface of the magnetic disk 203, and heats a portion of the magnetic recording layer of the magnetic disk 203. As a result, the coercive force of the portion is decreased to a value that facilitates writing; thus the thermally assisted magnetic recording can be accomplished successfully.
Detailed description of the laser diode module 232 follows now.
Referring to
Within the contemplation of the present invention, a light shielding structure is provided to prevent the undesired laser light interference to the adjacent thermal assisted magnetic head in the adjacent HGA pair. In this embodiment, the light shielding structure is a tilting structure arranged for the laser diode module 232.
As shown in
With this configuration of the tilting laser diode modules 232, the direction of the upward laser light 261 emitted from the laser diode 233 is changed with a minor inclining, thus the upward laser light 261 may not received by the photodiode 235′ of the adjacent laser diode unit 233′, and less light coupling is generated, therefore the detection result of the adjacent photodiode 235′ is accurate, and in turns, the laser power of the adjacent thermal assisted magnetic head 230′ is easy to control, finally thermal stability of the adjacent thermal assisted magnetic head is improved.
As an optional embodiment, as shown in
While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.
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