Flexure Crossbar Alignment for Slider Fly Height Stability
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Solution Overview
Problem
Existing flexure designs in hard disk drives fail to minimize fly height modulation during near-contact recording due to high-frequency vibrations, leading to kinetic energy transfer and increased wear on both slider and disk surfaces, which affects data recording accuracy and reliability.
Innovation Solution
A novel flexure system with a base portion, outrigger portions, and transverse crossbars that minimize energy transfer during head-disk interface events by positioning the slider's center of percussion directly below the crossbar axis, reducing kinetic energy storage and damping coefficient, and incorporating electrically conducting traces for mechanical and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing flexure designs are used in near-contact recording, then the slider can maintain contact with the disk surface, but high-frequency vibrations cause kinetic energy transfer and increased wear
Solution Approach 1:
The patent applies mechanical vibration principles by designing the flexure to have specific natural frequencies that avoid resonance with disk rotation frequencies. The flexure geometry is optimized to minimize high-frequency vibrations during near-contact recording, reducing kinetic energy transfer and fly height modulation while maintaining reliable slider-disk contact.
Solution Approach 2:
The patent changes physical parameters of the flexure including its stiffness, mass distribution, and geometric dimensions. By adjusting these parameters, the flexure's dynamic response is optimized to minimize vibrations and energy transfer during near-contact operation, resolving the contradiction between maintaining contact and reducing wear.
2Measurement precision
If the flexure stiffness in the radial direction is increased to maintain positioning accuracy, then read/write head positioning accuracy improves, but the flexure becomes less compliant with disk surface variations
Solution Approach 1:
The patent applies local quality by creating non-uniform stiffness distribution within the flexure structure. Different regions of the flexure have different stiffness characteristics - the radial direction has higher stiffness for positioning accuracy, while other directions maintain compliance for adapting to disk surface variations. This resolves the contradiction through spatially differentiated mechanical properties.
Solution Approach 2:
The patent uses composite material structures in the flexure design, combining materials or structural configurations that provide anisotropic mechanical properties. This allows the flexure to exhibit high stiffness in the radial direction for positioning accuracy while maintaining compliance in other directions for adapting to disk surface variations.
3Measurement precision
If the slider is mounted distally on the flexure, then radial positioning accuracy is maintained, but pitch moment during slider lift is insufficient
Solution Approach 1:
The patent resolves this contradiction by considering three-dimensional mounting configurations rather than simple distal mounting. The slider is positioned and oriented in multiple dimensions on the flexure, allowing the center of percussion to be vertically aligned with the flexure attachment point while maintaining radial positioning accuracy. This multi-dimensional approach enables both accurate positioning and adequate pitch moment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexure system stabilizes slider motion, increases the margin of clearance between the slider and disk surface, reduces read-back signal modulation, and minimizes wear and impedance, maintaining accurate fly height and data transfer efficiency.
Implementation Method 1
A novel flexure system with a base portion, outrigger portions, and transverse crossbars that minimize energy transfer during head-disk interface events by positioning the slider's center of percussion directly below the crossbar axis, reducing kinetic energy storage and damping coefficient
Implementation Method 2
As the disk is rapidly rotated by a spindle motor, hydrodynamic pressure causes an air flow between the ABS of the slider and the surface of the disk. This flow lifts the slider so that it literally flies above the surface of the disk (at a 'fly height') on a layer of air.
Data Source
AI summary
A flexure mounted slider and its method of fabrication is described, wherein the slider is affixed to a pair of highly compliant, transverse (to the longitudinal axis of a load beam) crossbars whose common axis passes directly above the center of percussion of the slider. The location of the center of percussion of the slider relative to the flexure eliminates translational motion of the slider during HDI events, but not twisting motion in a pitch direction during normal operation, and thereby minimizes the transfer of kinetic energy between the slider and the flexure during HDI events with a hard disk. The high compliance of the flexure crossbars to twists in a pitch direction, as well as the compliance of the outriggers to bending, allows the slider to pass over irregularities in the disk during normal operations.