Dynamic magnetic information storage or retrieval – Head mounting – For adjusting head position
Reexamination Certificate
2001-02-06
2001-12-18
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For adjusting head position
C360S294600
Reexamination Certificate
active
06331923
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to disk drive suspensions and, more particularly, to load beams for disk drive suspensions displaced by microactuators and having features allowing greater stroke sensitivity (or displacement response to microactuator elongation and contraction) for increased distance of stroke without loss of torsion performance with a given voltage input. The invention suspensions utilize microactuation by a piezoelectric crystal to shift the load beam distal end relative to the beam base portion over the disk to be read. The invention uses plural reverse deflections (or turns of direction) along the length of the suspension spring elements to provide a softer resistance to lateral movement and less constraint of the suspension movement that is responsive to longitudinal dimensional change in the piezoelectric crystals, while maintaining the structural integrity of the suspension. Manufacturing advantages accrue from the inventive use of the plural reverse deflections over the use of single deflections. Single deflections tend to spring back and plural, reverse deflections counteract this tendency. The invention enables effective microactuation of suspensions with the use of greatly reduced voltages, e.g. 5 volts, rather than 40 volts heretofore employed by virtue of heightened stroke sensitivity. Stroke sensitivity, measured in NMNOLT, is increased, for example, to over 41 NMNOLT from the just about 31 NMNOLT obtained with single deflection in the suspension spring elements.
2. Related Art
Load beams are used to carry sliders containing read/write heads adjacent spinning disks. The load beam has a base portion anchored to an actuator arm that pivotally shifts the load beam and its associated slider angularly to move between tracks on the disk. The mass and inertia of conventional actuators means it requires considerable power to operate them.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved suspension. It is a further object to provide a load beam of novel design and a method of forming such load beams and suspensions. It is a further object to provide for the actuation of a suspension load beam with microactuators acting against a beam spring portion having an improved expansion and contraction capability. It is a further object to utilize piezoelectric crystals acting between the load beam base potion and the beam portion across the spring portion under voltages of less than about 40 volts to as little as 5 volts or less and to increase the stroke sensitivity of microactuated suspensions to greater than 40 NMNOLT. It is a still further object to provide a load beam having specially conformed spring elements bent from the plane of the load beam to be disposed vertically to the load beam to support the beam portion from the base portion and also to readily allow changes in dimension of the spring portion through the decrease or increase in repeating reversed arcuate sections of the spring elements.
The invention accordingly provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable electrodynamic microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion angularly displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising a plurality of longitudinally extended, multiply reversely deflected spring elements providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the suspension includes right and left hand microactuators acting on the beam portion in displacing relation, the microactuator comprises a piezoelectric crystal, and the suspension has a stroke sensitivity above about 35 NMNOLT.
In a further embodiment, the invention provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable piezoelectric crystal microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising a plurality of longitudinally extended, multiply reversely deflected spring elements providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the spring portion comprises right and left spring elements, and the microactuator comprises right and left piezoelectric crystals coupled between the base and beam portions inboard of the right and left spring elements, the load beam spring portion extends in a plane, the spring portion having right and left side rails extending normal to the spring portion plane and defining respectively opposed right and left spring elements that extend laterally of the load beam, the spring elements being reversely deflected at spaced locations along their longitudinal extent to form spaced proximate and distal local arcuate sections, the sections extending parallel to the spring portion plane, the proximate arcuate sections open inwardly and are open toward each other across the spring portion, the distal arcuate sections open outwardly and are closed toward each other, and the spring elements converge on one another from their proximate ends to their distal ends.
Further, while the microactuators are typically bonded to the load beam, the invention contemplates a positive coupling of the load beam to the microactuators in lieu of or in addition to an adhesive bond. For this purpose, the microactuator and the load beam define cooperating inter fitting structures, the microactuator acting through the interfitting structures to displace the load beam.
The right and left piezoelectric crystals thus have proximate portions attached to the base portion and distal portions attached to the beam portion (includes a continuation of the spring portion attached to the beam portion), and intermediate portions between the proximate and distal portions, the arcuate sections being disposed opposite the crystal intermediate portions.
Typically, the arcuate sections are each deflected a like amount from their respective spring elements, the piezoelectric crystals each have outer edges, and the distal arcuate sections are closer to the crystal outer edges than the proximate arcuate sections, the suspension having a stroke sensitivity above about 35 NMNOLT.
In a further embodiment, the invention provides a center spring element as well as right and left spring elements. Thus, the invention in this embodiment provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable piezoelectric crystal microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising right, left, and central longitudinally extended, multiply reversely deflected spring elements providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the microactuator comprises right and left piezoelectric crystals coupled between the b
Bachand Louis J.
Magnecomp Corporation
Tupper Robert S.
LandOfFree
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