Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Patent
1991-09-16
1996-10-08
Heinz, A. J.
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
360 9807, 360 9808, G11B 5012
Patent
active
055637507
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to disk files, and in particular to a method of mounting a stationary shaft on which rotatable recording subassemblies such as a disk stack or rotary actuator can be mounted.
BACKGROUND OF THE INVENTION
One of the most common methods of storing digital data is to use a stack of one or more disks, mounted for simultaneous rotation about a common axis. Data are stored in concentric tracks about this axis on the surfaces of the disk or disks. The data are written onto and/or retrieved from these tracks by a transducing head, which can scan radially across the disk surface. By rotating the disk to the correct azimuthal angle, and moving the head to the correct radial distance, it is possible to access any point on the disk surface. The constant desire to increase the density of data storage on such disks means that the separation between adjacent tracks must be made as small as possible. This demands very accurate positioning of the head in order for the correct track to be located.
In one type of disk file, a stationary spindle shaft is rigidly fixed directly to a support structure. This support structure generally forms part of the walls of the disk file. The disks are mounted on a hub, which is caused to rotate about the spindle shaft by an electric motor within the hub. The heads are mounted on an actuator which produces their desired radial movement. This can be achieved either by rotating the actuator about a stationary shaft parallel to the spindle shaft, so that the head pivots in an arc across the disk surface, or else by linear motion of the actuator so that the head moves across the disk surface towards and away from the disk centre, effectively in a purely radial direction. The actuator is also mounted on the support structure: in the case of a rotary actuator, via an actuator shaft.
Often the spindle shaft is made of steel, which improves the efficiency of the in-hub motor, whilst the support structure is aluminium for lightness. Disk files of this general design are described in EP-0222939-A1 and U.S. Pat. No. 4,797,762.
For correct operation of the disk file, it is essential that each head can be accurately positioned over the desired track on the disk surface. This means that any uncontrolled movement of the head and the disk surface must be minimised, implying that the mountings and supports for the disk and the head must be as secure as possible. Usually the support structure comprises at least one piece of cast metal, the cast metal imparting mechanical strength and structural rigidity to the device. Note that in the type of disk file described above, the materials of the shaft and its support structure may be different, causing a potential problem with differential thermal expansion. Careful design of the means of attachment of the spindle shaft and actuator to the support structure is necessary to minimise unwanted movement of the disk and head.
U.S. Pat. No. 4,797,762 discloses one method of securing a shaft to its support structure in a disk file. The bottom of the spindle shaft is firmly glued into a hole in a first support structure, whilst the top of the spindle shaft is attached to a second support structure using a shouldered washer or bush. The shaft is bolted to the washer and the washer glued to the outer casing. The hole for the washer in the second support structure is slightly larger than the washer itself, allowing a certain leeway lest the holes for the top and bottom of the shaft are not quite properly aligned. By allowing this freedom in positioning of the washer, the washer can be glued into place to retain the shaft end in a stress-free manner. In this device, in common with many others, the top and bottom of the shaft are attached to two separate support structures. Such a design is susceptible to misalignment of the two shaft holes, and may also not hold the shaft as rigidly as desired.
The stability of the disk file can be improved if both ends of the shaft are attached to the same support structure. This is the case i
REFERENCES:
patent: 4875117 (1989-10-01), Slezak
Dew Graham N.
Hall Michael W.
Hearn Anthony R.
Young Julian T.
Billion Richard E.
Heinz A. J.
International Business Machines - Corporation
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