Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
2001-11-28
2003-03-11
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06532137
ABSTRACT:
This application claims the priority benefit of Japanese Patent Application No. 2000-363,528 filed on Nov. 29, 2000, and entitled “Disk Drive Apparatus, Hard Disk Drive, Filter and Method for Inspecting Disk Drive Apparatus.”
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk drive apparatus suitable for the hard disk drive (hereinafter, HDD) used as data storage means for computers, and particularly to a head assembly for reading/writing data from/to magnetic disk.
2. Background Art
The HDD, which is the most conventional data storage means for computers, has a structure in which a single or a plurality of magnetic disks are coaxially arranged and driven by a spindle motor. Data recording and writing are carried out by a magnetic head provided opposite to said magnetic disk, which is swung by an actuator, usually a voice coil motor (hereinafter, VCM). The above magnetic disks, magnetic head, and actuator are accommodated in a housing called a disk enclosure. The disk enclosure is formed of a base made of an aluminum alloy shaped in a thin case, and a top cover for sealing the opening of the base.
The storage capacity of a HDD depends on the specification of the computer on which it is mounted, and usually it has a single or plurality of magnetic disks to satisfy the storage capacity. For instance, if the storage capacity demanded of the HDD is 30 GB (gigabytes), three magnetic disks each having a storage capacity of 10 GB are prepared. However, there are various computer specifications, and a product having a HDD of 10 GB also exists. In this case, the disk enclosure and other parts are unified to support a plurality of storage capacities. For instance, the disk enclosure and other parts are previously designed so that a maximum of three magnetic disks each of 10 GB are mounted namely, an HDD of 30 GB is formed, and three magnetic disks are mounted if the required storage capacity is 30 GB, two disks are mounted for 20 GB, and one disk is mounted for 10 GB. Three magnetic disks can be mounted on this HDD, and the HDD that actually has three magnetic disks mounted thereon is called the full population version, while the HDD that actually has two or one disk mounted thereon is called the depopulation version.
In the depopulation version, the number of magnetic disks to be mounted on the HDD is increased or decreased according to the required storage capacity. Then, the number of magnetic heads for reading/writing data from/to magnetic disks is increased or decreased according to the number of magnetic disks. For instance, four magnetic heads are provided if the number of magnetic disks is two, and two magnetic heads are provided if the number of magnetic disks is one. If the number of magnetic heads is decreased, the weight decreases accordingly, which results in deviation of the center of gravity of the actuators to which the magnetic heads are attached. Thus, usually dummy heads are attached to the actuators to maintain their center of gravity.
3. Problems to be Solved by the Invention
By attaching dummy heads, the center of gravity of the actuators including magnetic heads, or of the head assembly can also be made to match the swing shaft in the depopulation version. It is important to cause the center of gravity of the head assembly to match its swing shaft for increasing the accuracy of the magnetic head positioning.
FIG. 5
is a perspective view showing the conventional head assembly using dummy heads. In
FIG. 5
, a head assembly
200
has, as the main structural elements of it, a pivot shaft holder
210
, a coil
220
for VCM (voice coil motor) which is attached to the pivot shaft holder
210
, arms
231
-
233
which are attached at positions symmetrical to the coil
220
for VCM with respect to the pivot shaft, suspension arms
241
-
244
which are attached to the end portions of the arms
231
-
233
, and magnetic heads
251
-
254
which are attached to the end portions of the suspension arms
241
-
244
.
It is assumed that the head assembly
200
performs data read/write for the HDD having two magnetic disks mounted or the HDD having one magnetic disk mounted as the depopulation version. For the HDD of the full population version on which two magnetic disks are mounted, as shown in the upper portion of
FIG. 5
, the four suspension arms
241
-
244
respectively having the magnetic heads
251
-
254
attached thereto are attached to the arms
231
-
233
. On the other hand, for the HDD of the depopulation version on which only one magnetic disk is mounted, as shown in the lower portion of
FIG. 5
, dummy heads
261
and
262
are attached where the suspension arms
241
and
242
are to be attached.
The head assembly
200
, in which the four suspension arms
241
-
244
are attached to the arms
231
-
233
, and the head assembly
200
, in which the two dummy heads
261
and
262
are attached, are both designed so that the center of gravity matches the swing shaft. However, by attaching the dummy heads
261
and
262
, a further resonance frequency affecting the performance of the HDD may occur in the head assembly
200
. Accordingly, it is required to adjust the center of gravity of the head assembly
200
without attaching the dummy heads
261
and
262
.
In Published Unexamined Utility Model Application No. 5-36655 Specification, there is disclosed a technique for adjusting the center of gravity of a head assembly. In the head assembly disclosed in Published Unexamined Utility Model Application No. 5-36655, a counter weight is fixed by a screw between the pivot shaft and the coil for VCM. However, the technique disclosed in Published Unexamined Utility Model Application No. 5-36655 is primarily intended to adjust the position of the center of gravity if the center of gravity deviates from the swing center of the head assembly. That is, it is not intended to adjust the center of gravity of the depopulation version head assembly.
Accordingly, it is an object of the present invention to provide a head assembly which enables the adjustment of its center of gravity for the depopulation version, while suppressing the occurrence of a resonance frequency affecting the performance of the disk drive apparatus.
SUMMARY OF THE INVENTION
In one embodiment of the present invention, the problems described above are solved by attaching a counter weight for adjusting the center of gravity of the head assembly of the depopulation version at a specific position on the head assembly. Accordingly, the present invention is a head assembly swinging over data storage media, the head assembly comprising a head for reading/writing data from/to the data storage media, an arm to which the head is attached, a swing shaft for supporting the arm, a coil for voice coil motor extended from the swing shaft, and a counter weight set at a predetermined position on the swing shaft which is on the side opposite to the coil for voice coil motor with respect to the swing shaft.
Since the counter weight is provided on the swing shaft, the head assembly of the present invention can reduce the occurrence of the vibration due to swing motion as compared with the dummy head attached to the arm, thereby to suppress the occurrence of a resonance frequency affecting the performance of the disk drive apparatus. Further, in the head assembly of the present invention, the counter weight is provided on the side opposite to the coil for the voice coil motor with respect to the swing shaft. This suggests that the counter weight is attached for the depopulation version, but it is not attached for the full population version, as detailed in the section of embodiments.
In the depopulation version, the number of data storage media is reduced from the full population version, and the number of heads is reduced accordingly. Thus, if the head assembly of the present invention is applied to the depopulation version, a plurality of the arms is provided, and there are existing arms to which the head is attached, and arms to which the arm is not attached.
Further, in the head assembly of
Huang Fu-Ying
Ohta Mutsuro
Takahashi Keishi
Takeuchi Kohichi
Bracewell & Patterson L.L.P.
Cao Allen
International Business Machines - Corporation
Martin Robert B.
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