Shear Mode Piezoelectric Micro-Actuator for Disk Drive Head Positioning
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Solution Overview
Problem
Current micro-actuators in disk drives face limitations in track density and data storage capacity due to insufficient frequency response, mechanical stiffness, and susceptibility to vibrations, which affect the precision and reliability of head positioning in magnetic and optical disk drives.
Innovation Solution
A collocated, rotational, shear mode piezoelectric micro-actuator is integrated into the suspension and head gimbal assembly, utilizing shear mode piezoelectric motors to provide rotational displacement for fine track positioning, enhancing mechanical stiffness and reducing vibrations, while minimizing mass displacement and particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voice coil motor (VCM) is used for head positioning, then seeking and coarse track following can be achieved, but resolution and frequency response are insufficient for high track density
Solution Approach 1:
The patent divides the actuation function into two stages: a VCM for seeking and coarse track following, and a piezoelectric micro-actuator for fine track positioning. This segmentation allows each actuator to be optimized for its specific function, with the piezoelectric micro-actuator providing the high resolution and frequency response needed for high track density applications.
Solution Approach 2:
The patent combines a VCM and a piezoelectric micro-actuator into a dual-stage actuator system that works together for head positioning. The VCM handles low-frequency, large-displacement movements while the piezoelectric micro-actuator handles high-frequency, small-displacement adjustments, achieving both good resolution and frequency response.
2Quantity of substance
If track density is increased to boost storage capacity, then more data can be stored, but head positioning precision and frequency response requirements become more stringent
Solution Approach 1:
The dual-stage actuator system segments the positioning task into coarse and fine adjustments, enabling the system to meet the stringent positioning precision requirements imposed by high track density while maintaining the ability to store large amounts of data.
3Measurement precision
If a piezoelectric micro-actuator is integrated into the suspension and head, then fine track positioning resolution and frequency response are improved, but mechanical stiffness and vibration susceptibility become concerns
Solution Approach 1:
The patent integrates the piezoelectric micro-actuator directly into the suspension and head gimbal assembly, merging it with the existing mechanical structure. This integration improves fine track positioning resolution and frequency response while the overall structural design maintains necessary mechanical stiffness and reduces vibration susceptibility.
4Measurement precision
If dual-stage actuators are used with VCM and micro-actuator, then seeking and fine positioning can be performed, but device complexity increases
Solution Approach 1:
The patent segments the actuation system into two distinct stages with clearly defined functions, which simplifies the control strategy compared to attempting to use a single actuator for all positioning tasks. The VCM handles the easy, low-precision seeking operations while the piezoelectric micro-actuator handles the difficult, high-precision fine positioning, making the overall system more manageable despite the added complexity.
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
This solution increases track density and data storage capacity by improving frequency response and mechanical integrity, reducing vibrations, and maintaining precise head positioning, thus enhancing the performance of disk drives and related equipment.
Implementation Method 1
A collocated, rotational, shear mode piezoelectric micro-actuator is integrated into the suspension and head gimbal assembly, utilizing shear mode piezoelectric motors to provide rotational displacement for fine track positioning
Data Source
AI summary
A rotational, shear mode, piezoelectric motor is integrated with a suspension, head or head gimbal assembly (HGA) into a collocated, rotational, shear mode, piezoelectric micro-actuated suspension, head or head gimbal assembly (HGA) for use in disk drives and disk drive manufacturing equipment. When excited by a control voltage, the collocated, shear mode, piezoelectric micro-actuated HGA rotates the head enabling high frequency, high resolution track positioning of the read/write element. The motor is integrated with the head and flexure (collocation). The head rotates about a rotation axis that is ideally located at the center of mass of the head. A shear mode piezoelectric motor rotates the head. A collocated, rotational, shear mode, piezoelectric micro-actuated HGA has high stiffness, high frequency response, high positioning resolution, low mass and low internal vibration for improved tracking, increased track density and greater disk drive storage capacity. Furthermore, its solid integration improves shock resistance and reduces micro-contamination.