Asymmetric PZT Electrode Configuration for Microactuator Stroke
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Solution Overview
Problem
Conventional microactuator assemblies in dual-stage actuated disk drive suspensions experience reduced stroke due to unbalanced extensions and contractions among PZT layers, leading to lower total stroke performance.
Innovation Solution
A novel configuration of PZT layers with electrodes of varying lengths, where the second and third layers have shorter active lengths than the first layer, allowing the microactuator to bend into a concave shape during extension and a convex shape during contraction, thereby increasing the total stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional PZT layers are configured with equal active lengths, then the structure is simple and easy to manufacture, but the stroke is reduced due to unbalanced extensions and contractions
Solution Approach 1:
The patent applies asymmetry by configuring the PZT layers with different active lengths. Specifically, the first PZT layer has a longer active length than the second and third PZT layers. This asymmetric configuration creates a deliberate imbalance in the piezoelectric actuation across layers, which generates a bending moment that increases the overall microactuator stroke during extension and contraction cycles.
Solution Approach 2:
The patent implements local quality by varying the active length of PZT layers at different positions within the stacked structure. The first PZT layer (at a specific location in the stack) has a different active length compared to the second and third PZT layers. This localized variation in geometric property optimizes the bending profile and stroke characteristics of the microactuator without requiring complete redesign of the entire structure.
2Measurement precision
If PZT layers have varying active lengths to increase stroke, then positioning accuracy and servo bandwidth are enhanced, but the device complexity increases
Solution Approach 1:
The asymmetric PZT layer configuration with varying active lengths creates different bending profiles during extension and contraction, which enhances the stroke and consequently improves positioning accuracy and servo bandwidth. The asymmetry is deliberately designed to optimize performance rather than increase complexity for its own sake.
Solution Approach 2:
The patent changes the geometric parameter (active length) of the PZT layers to optimize performance. By adjusting the active length of the first PZT layer relative to the second and third layers, the bending profile and stroke are optimized, leading to improved positioning accuracy and servo bandwidth while maintaining a relatively simple stacked structure.
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 increases the stroke of the microactuator by 5-25% by optimizing the bending profiles during both extension and contraction modes, enhancing the positioning accuracy and servo bandwidth of the disk drive suspension.
Implementation Method 1
A piezoelectric actuator assembly is described. The assembly including a first layer including a single active piezoelectric layer... A first electrode is disposed on at least a portion of the bottom surface of the first layer... The third electrode is configured to be shorter than the second electrode such that the active PZT length of the second layer and the third layer is shorter than the active PZT length of the first layer.
Data Source
AI summary
A piezoelectric actuator assembly is described. The assembly including a first layer including a top and a bottom surfaces. The assembly including a second layer having a top and a bottom surfaces, the bottom surface of the second layer is disposed over the top surface of the first layer. The assembly including a third layer having a top and a bottom surfaces, the bottom surface of the third layer is disposed over the top surface of the second layer. The assembly includes a first electrode, a second electrode, a third electrode, and a fourth electrode. The third electrode is configured to be shorter than the second electrode such that the active PZT length of the second layer and the third layer is shorter than the active PZT length of the first layer.