DSA Suspension Mid-Load Beam Dual Actuators
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Solution Overview
Problem
Dual stage actuated disk drive suspensions face challenges in minimizing vibration excitation and securing higher frequency modes due to the placement of PZT microactuators, which can lead to reduced servo bandwidth and potential damage from PZT cracking.
Innovation Solution
Placing PZT microactuators in the middle of the load beam, closer to the head slider and away from the mount plate, decouples actuation from the head stack, reducing vibration transfer and increasing structural stiffness to achieve higher frequency modes above 6 kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PZT microactuators are placed on the mount plate closer to the actuator arm, then fine control of the head slider is improved, but vibration excitation of the head stack assembly increases and servo bandwidth is reduced
Solution Approach 1:
The PZT microactuators are extracted from the mount plate location and relocated to the load beam, separating the fine positioning function from the vibration-prone mount plate area. This extraction removes the source of vibration excitation while preserving the fine control capability at a location that does not couple strongly to head stack assembly modes.
Solution Approach 2:
The load beam serves as an intermediary structure that carries the PZT microactuators away from the mount plate. This intermediate location provides mechanical isolation from the head stack assembly vibration modes while maintaining the necessary positioning functionality through the beam's structural connection.
2Reliability
If PZT microactuators are placed close to the actuator arm, then decoupling from head stack is improved, but structural stiffness is reduced and first bending mode frequency decreases
Solution Approach 1:
The load beam is designed with localized stiffening features at specific regions to maintain overall structural rigidity while allowing the PZT actuators to be positioned at locations that provide decoupling. This local quality enhancement ensures that stiffness is maintained where needed without preventing the beneficial positioning of actuators.
Solution Approach 2:
The placement of PZT microactuators asymmetrically positioned on the load beam creates an optimized configuration where the actuators are sufficiently distant from the head stack for decoupling, yet the beam's asymmetric structural design maintains necessary stiffness characteristics through strategic material distribution and geometric configuration.
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 configuration effectively reduces vibration excitation of the head stack assembly, enhances servo bandwidth, and minimizes stress on PZT microactuators, preventing cracking and ensuring reliable head positioning.
Implementation Method 1
A piezoelectric element, sometimes referred to simply as a PZT, is often used as the microactuator motor
Data Source
AI summary
A dual stage microactuated (DSA) suspension has two microactuators which are located approximately mid-load beam, and which are close to the stiffening edge rails of the load beam. A vertically extending C-spring is formed in the rails adjacent the microactuators in order to allow the microactuators to expand and contract.