Dynamic magnetic information storage or retrieval – Head mounting – For moving head into/out of transducing position
Reexamination Certificate
2001-02-21
2003-10-28
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head into/out of transducing position
C360S254900
Reexamination Certificate
active
06639758
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk drive apparatus, preferably, a hard disk drive (HDD) employed as a data storing device of a computer. More particularly, the present invention relates to an HDD having a ramp shape that employs a head loading/unloading mechanism.
2. Description of Related Art of the Invention
The HDD is the most popular data storing means for computers. The HDD is structured so that a single or a plurality of magnetic disks are disposed on the same shaft and driven by a spindle motor therein. The capacity of the HDD is decided in accordance with the specifications of the subject computer in which the HDD is installed. Usually, the HDD is provided with one or more magnetic disks to satisfy the required capacity. For example, if 5 GB (gigabytes) is requested as the capacity of the HDD, five 1 GB magnetic disks (1 GB/disk) will be prepared. However, because there are a variety of computer specifications, 4 GB and 3 GB HDDs are also prepared.
The main components of a typical HDD are a magnetic disk and a spindle motor for driving the magnetic disk, and a case for holding and housing the magnetic disk, the motor, and other parts. This case is referred to as an enclosure case. One type of enclosure case can correspond to a plurality of capacity types. For example, if an enclosure case is designed in expectation that the HDD will be provided with five 1 GB magnetic disks so as to compose a 5 GB HDD, then the HDD will be provided with five 1 GB magnetic disks to comply with a requested capacity of 5 GB and with three 1 GB magnetic disks for a requested capacity of 3 GB. Such an HDD is referred to as a depopulation version HDD.
In a very compact and thin type HDD, for example, where the subject HDD is provided with a magnetic disk of 1 inch size, both sides of the magnetic disk are formed as recording surfaces and a magnetic head is prepared for each of those recording surfaces. If the capacity of one recording surface is 170 MB in such a thin type HDD, the HDD can have two capacity types; 340 MB and 170 MB. If a 340 MB HDD is defined as a standard one, the 170 MB HDD can be manufactured as a depopulation version of a 340 MB HDD in which only one side of the magnetic disk is used as a recording surface. In this case, the HDD has only one magnetic head for its one recording surface while the standard 340 MB HDD has two magnetic heads for its two recording surfaces.
Contact start-stop type disk drive apparatuses have been the main stream so far. In such a contact start-stop type disk drive apparatus, such a disk-like recording medium as a magnetic disk or the like is rotated, thereby generating an air bearing. The air bearing makes a head slider float from the surface of the disk so as to write data on the recording medium and read data from the recording medium. The head slider is mounted at a suspension arm composing a head arm of an actuator mechanism. In such a contact start-stop type HDD, however, the head slider is grounded on a save area on the disk surface when the rotation of the recording medium is stopped.
In a contact start-stop type disk drive apparatus, the head slider may possibly be sucked onto the surface of the data area and/or moved to the data area by a shock, thereby damaging the surface of the disk. To avoid such troubles and improve the reliability of the apparatus at the rest time, therefore, a load/unload type disk drive apparatus has been developed for commercial use. For example, such a load/unload type HDD is provided with a suspension arm for holding a magnetic head, as well as a part referred to as a ramp block. This HDD, while it is at rest, enables the ramp block to hold the suspension arm, thereby the head slider is prevented from touching the surface of the disk while the head slider is unloaded in the save area. The suspension arm has a load/unload tab having a projection and a ramp is formed at the ramp block. The ramp block is disposed so as to be close to the outer peripheral portion of the disk.
The loading/unloading mechanism, when the operation of the disk drive apparatus is stopped, rotates the suspension arm, thereby placing the projection of the load/unload tab of the suspension arm on the tab holding position so as to unload the head.
FIG. 6
shows a magnetic disk
150
, a suspension arm
160
, and a ramp
170
. In
FIG. 6
, only one suspension arm
160
is shown so as to simplify the description for better understanding.
A load/unload tab
161
is formed at the suspension arm
160
. The suspension arm
160
is rotated by a VCM (Voice Coil Motor not illustrated) in the radial direction of the magnetic disk
150
, that is, towards
150
A or
150
B. At the ramp
170
are formed a load/unload surface consisting of a first slope surface
171
, a flat surface
172
, a second slope surface
173
, and a supporting surface
174
.
When data writing/data reading on/from the magnetic disk
150
is finished, the VCM rotates the suspension arm
160
towards
150
B, that is, in the unloading direction. The load/unload tab
161
of the suspension arm
160
rubs against the flat surface
172
after climbing the first slope surface
171
of the ramp
170
. The tab
161
then goes down the second slope surface
173
and stops on the supporting surface
174
. At the time of starting writing/reading data on/from the magnetic disk
150
, the load/unload tab
161
of the suspension arm
160
, which has stopped on the supporting surface
174
, climbs the second slope surface
173
, then rubs against the flat surface
172
, and goes down the first slope surface
171
to be loaded in the direction
150
A.
Because the load/unload tab
161
of the suspension arm
160
rubs against the ramp
170
on the loading/unloading condition of the head, a friction torque is generated between them. Therefore, the driving force of the head driving mechanism including the VCM is determined by taking this friction torque into consideration.
In case of a 1-inch-diameter HDD as described above, if the HDD is provided with two magnetic heads, the HDD has two suspension arms
160
. Therefore, if a friction torque Tf is generated when one suspension arm
160
climbs the second slope surface
173
on the loading condition of the head, the total friction torque will become 2Tf. Consequently, the head driving mechanism including the VCM must have a driving force enough to load the suspension arms
160
against this 2Tf.
However, if the HDD is a depopulation type one provided with only one magnetic head, the HDD has only one suspension arm
160
. The total friction torque will thus become Tf. The head driving mechanism of the depopulation version HDD conforms to that of an HDD provided with two magnetic heads. At the time of loading the head, a current is applied to the VCM and when the suspension arm
160
reaches the flat surface
172
, the speed of the suspension arm
160
is detected with use of the counter electromotive force of the VCM. After that, the speed of the suspension arm
160
, that is, a current supplied to the VCM is controlled. Consequently, if the HDD is provided with only one magnetic head, thereby the total friction torque becomes a half of that of an HDD provided with two magnetic heads, then the suspension arm
160
, that is, the magnetic head reaches the magnetic disk
150
before the power supplied to the VCM is controlled. As a result, the current might not be controlled in some cases.
In case of a 1-inch-diameter HDD, the HDD is manufactured basically as an analog of, for example, an 2.5-inch-diameter disk HDD. Consequently, the diameter of the coil composing the VCM becomes small just like in the 2.5-inch-diameter HDD. The counter electromagnetic force obtained from the VCM is in proportion to the square of the coil diameter. For example, if the diameter of the coil of a 2.5-inch-diameter HDD is 2.5 mm, the diameter of the coil of a 1-inch-diameter HDD is 1 mm. The counter electromagnetic force obtained from the 1-inch-diameter HDD is thus about 16% of that of the 2.5-inch-diameter HDD. Co
Matsuda Hiroshi
Nakamura Takahide
Ohta Mutsuro
Takahashi Keishi
Heinz A. J.
Hitachi Global Storage Technologies - Netherlands B.V.
Klein Esther E.
Nunnelley Lewis L.
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