International Business Machines Corporation

Other

Richard W Luoma

Zine-Eddine Boutaghou

John Beck

James M Rigotti

John R Reidenbach

Luke A Cossette

Peter M Herman

Darrell Eugene Bratvold

Daniel O Castrodale

Clarence R Schwieters

Willard Leon Gudgel

Arthur P Brende

Glenn A Benson

William Kenneth Aylsworth

A rigid disk drive spindle motor includes a bobbin carried by the motor hub which has a permanent magnet attached to the inner cylindrical surface and a laminated back iron mounted at the outer cylindrical surface. The laminated back iron may be in the form of concentric cylinders or a spiral wound strip with adjoining cylinders or convolutions secured to and electrically separated from one another by an adhesive material. In another form, the back iron may be formed as a series of washer like rings mounted on the bobbin which is a configuration similar to the laminations used in the motor stator and would permit fabrication using the same manufacturing techniques. The back iron is formed of high resistance silicon steel so that both the back iron material and the laminated structure discourage Eddy current formation. The spiral wound embodiment may also be modified by having the spiral strip periodically, axially interrupted to further reduce undesired induced currents. Use of the bobbin serves to assure the concentricity of the closely adjoining stationary and rotary parts of the spindle motor and to facilitate easier manufacture and assembly. To further confine the magnetic fields, laminated fringe ring assemblies are provided at each axial end of the back iron structure. These assemblies are formed of washer like rings of permeable material that are secured to one another and electrically separated by adhesive material.

Laminated back iron structure for increased motor efficiency

Laminated back iron structrue for increased motor efficiency

A magnetic fluid seal is provided by mounting an annular, axially polarized magnet mounted on the device base member and an annular ring pole piece with an inner diameter that cooperates with an outer diameter surface of the hub assembly to form a fluid gap that is radially outward and within the axial extent of the spindle bearings. The secondary gap of the seal assembly is within the bearing assembly sealed volume while the principal sealing gap is within the hub assembly to confine any debris or aerosols resulting from high rotational velocity or shock to be contained in proximity to the flux fields that can recapture any magnetic material. The assembly also inherently presents an effective conductive path to provide enhanced grounding of the rotating assembly through the magnetic fluid in the second gap which is not subject to impairment caused by bonding materials. The seal assembly design also provides for self loading of the magnetic fluid without permitting escape of smeared liquid beyond the region of the seal assembly.

Magnetic fluid seal and ground path for low profile disk drives

The instability of a cage in a precision ball bearing at high speeds may be eliminated by controlling the position of the cage. The control of a position of a cage is accomplished by forming three ball pockets or holes in the cage for the balls of the ball bearing assembly to a dimension that will result in a tight running fit between the ball and the ball pocket. A tight running fit between the ball and the cage is found in three of the ball pockets in a ball bearing assembly while the diameter of the large ball pockets or other remaining ball pockets is enlarged to provide a clearance between the balls and the cage which is at least twice the clearance between the ball and the guide ball pocket having the tight running fit, and preferably three to five times that clearance. When properly lubricated, the tight running fit will insure stabilization and control of the cage so that the cage remains stable at high rotational speeds.

Direct access storage device having a stable ball bearing cage design

An enclosure for a rigid disk data file is shown which includes a base casting and a cover that interface along planar surface that is not perpendicular to the axis of the spindle supporting the data disks. The base casting at one side extends axially along the disk stack and has the transducer positioning actuators mounted through openings therein. At the opposite side, the disk stack is fully exposed to permit easy access to the disk surface for procedures such as servo writing during manufacture of the drive. This structure makes possible concurrent operation of the product heads and servo writing heads.

Disk drive enclosure with an inclined parting surface

An actuator for positioning transducers with respect to a disk storage device data surface provides a substantially sealed head-disk enclosure from which the voice coil motor permanent magnets are excluded. The mounting flange-inner core member, end cap and collar and shorted turn provide a sealed enclosure about the transducer carriage, voice coil and working air gap of the voice coil motor (VCM) with the permanent magnet and outer core pieces assembled to the device thereafter. The permanent magnets can be excluded from the clean room assembly area and this source of the most destructive particulate contamination are outside the head-disk enclosure.

Disk drive with isolated voice coil motor magnet

Shown and described is a recirculating air system for a disk drive assembly wherein air moves radially over the disk surfaces, over the transducer carriage at an increased velocity, past the actuator mechanism and through a filter before recirculation is induced by the hub assembly on which the disks are mounted and which functions also as an impeller. The hub-disk assembly also forms an integral part of the drive motor rotor assembly. Also, a breather filter and breather opening communicate with the recirculating air path at the low pressure location of the recirculating path to assure that air entering the system passes through the breather filter.

Self-ventilated recirculating airflow system

The magnetic head actuator includes a substantially totally enclosed self-shielding voice coil linear motor which includes a continuous, cylindrical permanent magnet of flexible material which is sealed against the inner cylindrical wall of the outer core by a flared copper sleeve that also serves as a non-magnetic, conductive shorted turn to reduce instantaneous inductance of the drive coil. An annular reluctance gap in the outer core provides symmetrical distribution of the permanent magnet flux.

Linear moving coil actuator

A punching, reading and printing machine for document cards having a hopper holding the cards in vertical disposition, card transporting means moving the cards out of the hopper into horizontal disposition in a horizontal card path and closely spaced punching, reading and printing mechanisms operative on the cards while in the horizontal path. The punching mechanism includes a row of punches extending transversely of the card path each made active by an interposer and a leaf spring actuator for the interposer, and the printing mechanism includes a row of print hammers extending longitudinally of the card path and an electromagnet and armature for each of the print hammers. The interposer springs extend longitudinally of and over the path of card travel preceding the punches, and the armatures extend transversely of the machine for shortening the machine and rendering it more compact.

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Rochester, MN, United States of America

Richard W Luoma