Piezoelectric Actuator Slanted Electrode Angles
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Solution Overview
Problem
Existing piezoelectric actuators with slanted surfaces on the lower electrode face challenges in achieving uniform orientation of the piezoelectric body, leading to ineffective driving regions and reliability issues due to compromised coverability of insulating films.
Innovation Solution
The actuator design features a first electrode with multiple slanted surfaces, where the angle between the substrate and the farthest slanted surface is smaller than that of other slanted surfaces, enhancing the effective region of the piezoelectric body while maintaining high reliability through improved coverability of insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slanted surface is formed at the end portion of the lower electrode to improve insulating film coverability, then the coverability is improved, but the piezoelectric body develops ununiform orientation reducing the effective driving region
Solution Approach 1:
The end portion of the lower electrode is divided into multiple slanted surfaces with different slant angles rather than a single slanted surface. This segmentation allows different regions to serve different functions: some regions provide gentle slopes for good insulating film coverability, while other regions provide steeper slopes to maintain piezoelectric body orientation and effective driving region.
Solution Approach 2:
Different slanted surfaces are assigned different local properties (different slant angles) according to their specific functional requirements. The slanted surfaces closer to the substrate have smaller angles for better film coverage, while those farther away have larger angles to preserve the piezoelectric body's effective region, creating locally optimized conditions throughout the structure.
2Reliability
If the slant angle of the slanted surface is made small to improve insulating film coverability, then the coverability is improved, but the horizontal length of the slanted surface increases reducing the effective region of the piezoelectric body
Solution Approach 1:
The total horizontal length required for insulating film coverage is distributed across multiple slanted surfaces with different angles. This segmentation allows the gentle slope requirement to be met over a distributed path while minimizing the horizontal encroachment on the piezoelectric body's effective region compared to a single long slanted surface.
Solution Approach 2:
Instead of using a single slanted surface that extends horizontally, the solution introduces multiple slanted surfaces at different angles and positions. This transforms the problem from a one-dimensional horizontal trade-off to a two-dimensional configuration where vertical positioning and angular variation work together to achieve both film coverage and preserve effective area.
3Area of stationary object
If the end portion of the lower electrode is made perpendicular to avoid reducing the effective region, then the effective region is maintained, but the insulating film coverability deteriorates
Solution Approach 1:
Rather than using a single perpendicular end portion, the structure is segmented into multiple slanted surfaces. This allows the piezoelectric body to maintain its full effective region while the insulating film is accommodated through the stepped configuration of multiple surfaces, each with appropriate angles for film coverage.
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 design effectively expands the piezoelectric body's operational region, enhances actuation efficiency, and improves the reliability of the actuator by optimizing the slanted surface angles and insulating film coverage.
Implementation Method 1
An actuator using a piezoelectric body, which changes its shape upon application of an electric field
Data Source
AI summary
An actuator has a first electrode, a piezoelectric body, and a second electrode that are on a surface of a substrate in this order and an insulating film covering at least a side surface of the piezoelectric body. The actuator has a plurality of slanted surfaces slanted relative to the substrate at an end portion of a surface of the first electrode which is opposite from the substrate, and an angle between the substrate and a first slanted surface of the plurality of slanted surfaces which is farthest away from the substrate is smaller than an angle between the substrate and any other one of the slanted surfaces.