Piezoelectric Speaker Diaphragm Vibration Control
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Solution Overview
Problem
Piezoelectric acoustic transducers produce disturbed sound waves due to unregulated vibrations of the metal plate, which are not aligned with the outer shape of the piezoelectric ceramic, resulting in suboptimal sound quality.
Innovation Solution
A speaker element with a diaphragm featuring connection pieces protruding from its edge, thicker than the diaphragm's sheet thickness, and an annular wall, which supports the diaphragm to stabilize its vibrations and align them with the piezoelectric element's deformation, reducing unwanted vibrations and improving sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the entire perimeter of the metal plate is fixed, then the vibrations are well-regulated, but the metal plate cannot vibrate freely resulting in lower sound output
Solution Approach 1:
The continuous perimeter connection is segmented into discrete connection pieces (at least six) distributed around the outer edge of the diaphragm. This segmentation allows different regions to have different degrees of freedom - the connection pieces provide regulation while the spaces between them allow free vibration, resolving the contradiction between vibration regulation and sound output.
2Speed
If protrusions are disposed around the metal plate to regulate vibrations, then resonance frequency can be shifted lower, but the standing wave pattern becomes independent of the piezoelectric ceramic shape causing disturbed sound waves
Solution Approach 1:
Instead of uniform protrusions around the entire perimeter, the connection pieces are strategically positioned at specific locations around the outer edge of the diaphragm. This local quality approach allows the standing wave pattern to conform to the piezoelectric element's shape while still providing vibration regulation, eliminating disturbed sound waves while maintaining low resonance frequency.
3Reliability
If the connection pieces have greater thickness than the diaphragm, then the diaphragm is properly supported, but the device complexity increases
Solution Approach 1:
The connection pieces integrate multiple functions: they provide mechanical support for the diaphragm, serve as connection points to the case, and define the vibration pattern. By merging these functions into a single structural element with varied local thickness, the design achieves reliable diaphragm support without proportionally increasing device 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
The solution stabilizes the diaphragm's vibrations, ensuring they conform to the piezoelectric element's shape, thereby reducing disturbed sound waves and enhancing sound quality by aligning the standing wave pattern with the piezoelectric element's deformation.
Implementation Method 1
a piezoelectric element that is layered on the diaphragm and becomes deformed under application of a voltage to cause the diaphragm to vibrate
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A diaphragm (3) has a plurality of connection pieces (5) disposed on an outer edge of a major surface (3A), the connection pieces (5) protruding outward along the major surface (3A) and being connected to an outer frame (4). A piezoelectric element is layered on the diaphragm (3) and becomes deformed under application of a voltage to cause the diaphragm (3) to vibrate. The thickness of the connection pieces (5) along a z-axis direction is greater than a sheet thickness of the diaphragm (3) in a region on which the piezoelectric element is layered. The connection pieces (5) protrude from the major surface (3A) in the z-axis direction.