Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
1998-11-05
2002-12-03
Miller, Brian E. (Department: 2754)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06490123
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
A present invention relates to a magnetic disk drive, particularly, rotating a magnetic disk medium in a high speed and a magnetic disk drive system using this technique.
2. Description of the Related Art
In a magnetic disk drive system that is used as a high precision external storage, for example, a computer, a file server or a disk array, it is well known that a magnetic head flies a given distance over a recording surface of a magnetic disk medium in the magnetic disk drive system, so that information is recorded on or reproduced from the magnetic disk medium via a magnetic flux.
Performance of magnetic disk drives greatly affects the throughput of the magnetic disk drive system. For better performance, there are typically the following improvements of the system.
1) a memory capacity improvement within a limited system hardware (Increase of an information storage capacity per unit volume)
2) retrenchment of time for moving a magnetic head to a dedicated track on the magnetic disk medium (Shortening of seek time)
3) retrenchment of waiting time in rotation for waiting a magnetic head to a dedicated location at the specified position of a truck of the magnetic disk medium
These items were resolved in the present invention by an increase of rotational speed of the magnetic disk media, which also increases an input-output transfer rate of information between magnetic disk drive and upper system, and between magnetic disk drive system and upper system.
There is a “3.5 inches” form factor drive that is well known. Here, “3.5 inches” is called the shape coefficient. “3.5 inches” size means a magnetic disk drive which is about 4 inches (101.6 mm) in width, and about 5.75 inches (146.1 mm) in length. It usually is about 1 inch in height unless otherwise specified.
In case a rectangular parallelepiped circumscribes a magnetic disk drive, let's imagine the largest face that is parallel to the magnetic disk medium. At this time, the largest face of the “3.5 inches” drive can include two largest faces of a “2.5 inches” drive. Similarly, a largest face of the “5 inches” drive can include two largest faces of a “3.5 inches” drive. The shapes that fall in the above relationships are called form factors.
The conventional “3.5 inches” magnetic disk drive has a structure, in a housing with 3.5 inches shape coefficient, which comprises: an arm than supports magnetic head parts, a carriage with the arm, which positions the magnetic head to the specified location on the magnetic disk media, an in-hub-type spindle motor that has rotational mechanism within a hub that holds the magnetic disk media on its outer surface, and magnetic disk media of which most outside diameter is 95 mm stacked on the hub (hereinafter called “3.5 inches” disk for short)
Here, there are “3.5 inches” magnetic disk drives which have mainly about 1 inch (25.4 mm) height or about 1.63 inches (41.4 mm) height.
FIG. 3
shows an inner structure (plan view) of prior “3.5 inches” magnetic disk drive. External size of the housing
13
is a 3.5 inches form factor size (101.6 mm×146 mm). Magnetic disk media
23
are secured by a disk clamp
33
to a spindle motor
43
, which are rotated at predetermined speed in this housing.
Magnetic heads
53
are secured to an edge of an actuator (the carriage and a coil)
63
. The actuator
63
is secured rotatably by a pivot bearing
73
to the housing. The housing
13
secures a voice coil motor
83
that consists of a magnetic circuit. The coil of the actuator
63
is flowed by electricity, then it generates a rotational torque with electromagnetic force and drives the actuator
63
. Consequently, the magnetic head
53
supported at the edge of the actuator executes a seek operation in which the head are located at an artbitrary location on the disk media
23
along a quasi-radial direction.
In the 1.6 inches height magnetic disk drive with an about 41 mm official height, the spindle motor
43
is mounted stackingly with eight “3.5 inches” disk media (0.8 mm thickness). In 1 inch height magnetic disk drive with an about 25.4 mm official height, it is mounted stackingly with four “3.5 inches” disk media.
Other prior arts about faster rotating technique of spindle motors are disclosed, for example, at Japanese Laid opened, sho 63-104282 (corresponding to U.S. Pat. No. 5,243,479) and at Japanese Laid opened, hei 04-205776 that shows stacking structures with “3.5 inches” disk media or “2.5 inches” disk media in a housing of 5.25 inches of shape coefficient.
Inventors of this application tried to rotate magnetic disk media of 1.6 inches height magnetic disk drive shown in
FIG. 3
faster than in prior arts. They confirmed that when a rotational speed of spindle motor
43
becomes 10000 rpm from 7200 rpm (prior rotational speed), electric energy consumption increases with about 60 percent and becomes more than 20 watts despite a lightweight design review that decreases the disk media
23
from 10 disks to 8 disks in the stack.
They also confirmed that an inner temperature of the housing
13
becomes more than 80 degree centigrade without cooling means surrounding the 1.6 inches height magnetic disk drive shown in FIG.
3
. The cooling means are, for example, a fan that makes air flow for cooling.
Inventors of this application tried to rotate magnetic disk media of 1.6 inches height magnetic disk drive shown in
FIG. 12
faster than in prior arts. When a rotational speed of spindle motor
43
becomes 12000 rpm from 6300 rpm (prior rotational speed), electric energy consumption increases with about 460 percent.
Japanese Laid opened, hei 4-205776 shows a magnetic disk drive that mounts a stack of magnetic disk media smaller in outer size than that of “5.25 inches” magnetic disk media within a housing that is designed for a 5.25 inches form factor size magnetic disk drive. But it does not consider an increase of heat generation caused from faster rotation and higher density mounting.
Japanese Laid opened, sho 63-104282 (corresponding to U.S. Pat. No. 5,243,479) does not consider fully a heat radiation while it discloses an increase of rotational speed of magnetic media.
Inventors of this application mounts magnetic disk media for “2.5 inches” form factor magnetic disk drives, in the housing for 1.6 inches height “3.5 inches” magnetic disk drive. And further they rotates the media at 12000 rpm in order to fabricate a magnetic disk drive with a high transfer rate of information (
FIG. 13
, FIG.
14
). Inventors of this application found that it is necessary for keeping the inner temperature equal to or lower than 60 degrees centigrade to mount eight disk media or less when 0.8 mm thickness media are adopted and to mount eleven disk media or less when 0.635 mm thickness media are adopted. That is, they found that it is possible to rotate disk media faster with victimizing the information storage capacity in some extent, and that the storage capacity and the faster rotation of the media are in the trade-off relationship.
Here, disk media for the 2.5 inches form factor magnetic disk drive have a 65±3 mm diameter (outermost diameter) and a 0.8 mm±0.2 mm thickness or a 0.4 mm±0.2 mm thickness. Normal thicknesses of the media are 0.8 mm, 0.635 mm or 0.381 mm.
One of the reasons why the inner temperature of the housing (during a seek operation) is kept in the predetermined temperature or less, for example, 60 degree centigrade or less, is to get a long life of the disk drive by setting an enough margin in temperature for long lives of a lubricant on the disk media surface and a grease in bearings of the spindle motor. Another is not to give a bad influence to a status between the magnetic head and the magnetic disk media, and to a posture of a slider. Consequently, recording or reproducing with a information to or from the disk media are not influenced badly. Thus, temperature specifications of the magnetic disk drive can be guaranteed.
Thus, inventors of this application found that it is necessary for making the stack of
Akira Chuma
Ishigaki Tatsuya
Iwakura Masao
Kodama Naoki
Kojima Toshiaki
Hitachi , Ltd.
Miller Brian E.
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