Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
1999-11-17
2002-07-09
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06417985
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to magnetic disk drives, which drive spindle motors to rotate magnetic disks so that magnetic heads read and write information on the magnetic disks. Particularly, this invention relates to improvements in mechanical structures of the magnetic disk drives whose thickness is reduced and which are improved in impact resistance and heat radiation.
This application is based on Patent Application No. Hei 10-328658 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
First, a description will be given with respect to impact resistance of the conventional magnetic disk drives.
In general, the magnetic disk drives are very weak against impact being applied from the external. So, there is a possibility that the magnetic disk drives are remarkably reduced in life when human operators (or users) drop the magnetic disk drives on desks so that small impact of 100 G is applied to the magnetic disk drives. For this reason, in an event in which the user drops the magnetic disk drive from the desk to the floor so that large impact of 1000 G or more is applied to the magnetic disk drive, the magnetic disk drive may be fatally damaged.
There are two reasons why the magnetic disk drives have weakness against the impact, as follows:
A first reason is occurrence of jumping in which the magnetic head jumps due to impact being applied to the magnetic disk drive. In that case, the magnetic head hits a magnetic recording medium, so that a medium surface and the head are damaged. It is known that in general, the head is subjected to jumping due to impact of 100 G or so.
To avoid occurrence of the jumping of the head, the conventional technology employs a method to refuge the head outside of the medium at a stop mode of the magnetic disk drive. Even in such a method, however, it is unavoidable that a suspension portion for supporting the head is deformed and damaged due to impact of 1000 G or more.
A second reason is damageability in which a bearing of a spindle motor for rotating the medium is easily damaged.
In case of a ball bearing, for example, load corresponding to a product of “(impact acceleration)×(mass of body of revolution)” concentrates at the bearing. This causes impressions to be formed on a ball and its sliding surface.
To avoid the above problems, engineers discuss using pressure bearings as the bearings. The pressure bearing receives impact by “line contact”, which approximates to “surface contact”. As compared with the ball bearing, the pressure bearing is improved in impact resistance. Until now, however, the pressure bearing does not have sufficient reliability to accomplish required functions of the bearing. So, the present technology does not proceed to adoption of the pressure bearing to the magnetic disk drive. Even if the magnetic disk drive uses the pressure bearing, the pressure bearing merely provides impact resistance of several-hundreds G class. So, it cannot be said that the magnetic disk drive using the pressure bearing sufficiently overcomes large impact which exceeds 1000 G.
To cope with the aforementioned problems, engineers and scientists propose a variety of techniques with regard to shock absorber mechanisms of the magnetic disk drives.
For example, Japanese Patent Application, First Publication No. Hei 4-368690 discloses a magnetic disk drive, which is equipped with shock absorbers made of chloroprene rubber at four corners of a housing.
Japanese Patent No. 2594760 (corresponding to Japanese Patent Application, First Publication No. Hei 8-36873) discloses a magnetic disk drive equipped with shock absorbers (or bumpers) made of elastic material, which are installed in recesses formed at outer edge portions of a base of the magnetic disk drive.
In addition, Japanese Patent Application, First Publication No. Hei 6-176555 discloses a magnetic disk drive equipped with a shockabsorber added structure. Herein, shock absorbers are arranged at four corners of a frame as well as some portions in proximity to both ends of a connector receiving portion. Those shock absorbers damps impacts being applied to the magnetic disk drive. So, it is possible to prevent internal mechanical parts and members of the magnetic disk drive from being damaged.
Next, a description will be given with respect to measures against the heat that the magnetic disk drives generate. In general, the magnetic disk drive is constructed by a disk enclosure for installing mechanical parts such as a spindle motor and an actuator as well as a package for mounting electronic components used for control.
Among the aforementioned parts and components, main heating sources are the spindle motor, a coil portion of the actuator and IC parts such as control channels.
It is well known that if the magnetic disk drive operates for a long time, a surface temperature increases by 30 degrees or more. If a using environment is severe in temperature which exceeds 50 degrees (Celsius), there is a possibility in which temperature of the magnetic disk drive exceeds 80 degrees (Celsius). In such an high-temperature event, the magnetic disk drive is placed in an uncontrollable state, so it malfunctions.
To cope with the aforementioned problem, the conventional technology uses a fan which is arranged in a housing (or case) installing the magnetic disk drive. Using such a fan, the magnetic disk drive is cooled down to avoid temperature increase.
Japanese Patent Application, First Publication No. Hei 9-115279 discloses a magnetic disk drive equipped with heat conductive members as heat radiators. Herein, heat conductive members are tightly adhered to the package, disk enclosure and housing. Specifically, heat conductive sheets are inserted into a gap between the disk enclosure and electronic components on the package as well as a gap between the disk enclosure and a wall of a housing for installing the disk enclosure. Those sheets radiates heat of the package and heat of the disk enclosure due to thermal conductivity.
Next, a description will be given with respect to a conventional installation method for installing the package mounting electronic components in the disk enclosure.
The conventional 3.5-inch (or 2.5-inch) magnetic disk drives using 3.5 inch (or 2.5 inch) disks employ a specific structure for installation. For example, the magnetic disk drive disclosed by Japanese Patent Application, First Publication No. Hei 9-115279 employs a structure in which the package is attached to a back of the disk enclosure.
The aforementioned structure is subjected to standardization, which determines positions for screwing the disk enclosure on the housing and a position for arranging a connector on the package. Thus, it is possible to install the magnetic disk drives in spaces, which are prepared in advance in personal computers and servers, with compatibility.
In general, the packages are uncovered. So, users are able to directly touch important electronic components of the packages.
As described above, the 3.5-inch (or 2.5-inch) magnetic disk drives are standardized in structures for installation in the housings (or main bodies). So, the magnetic disk drives are tightly screwed on the housings.
In the case of the personal computers, the magnetic disk drives are fixed to sheet metals of the housings by screws, so they are installed in the housings. In the case of the servers, the magnetic disk drives are fixed to racks exclusively used for installation of the magnetic disk drives by screws, then, the racks are inserted into the servers.
The packages normally use SCSI connectors or IDE connectors (where “SCSI” is an abbreviation for “Small Computer Systems Interface”, while “IDE” is an abbreviation for “Integrated Device Electronics”). Those connectors are not designed in consideration of repetition of insertion and extraction which are repeated many times. So, they are connected to the hard disk drives with very strong connecting forces.
The aforementioned conventional techniques regarding th
Heinz A. J.
NEC Corporation
Young & Thompson
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