Piezoelectric Ultrasonic Sensor Electrode Layout for Low Reverberation
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Solution Overview
Problem
Existing ultrasonic sensors suffer from spurious vibrations and increased reverberation times due to asymmetrical electrode configurations, leading to deteriorated reverberation characteristics and reduced vibration intensity.
Innovation Solution
The ultrasonic sensor design includes a piezoelectric element with symmetrically arranged electrodes, where the second electrode extends to both end edges in one direction and is spaced apart in an orthogonal direction, allowing direct wiring connection without additional members, enhancing vibration intensity and reducing spurious vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If asymmetric electrode configuration is used for direct wiring connection, then device complexity is reduced, but spurious vibrations increase and reverberation characteristics deteriorate
Solution Approach 1:
The patent applies asymmetry principle by intentionally designing the electrode configuration to be asymmetric with respect to the piezoelectric element center. The first electrode is positioned at a first location and the second electrode at a second location, creating an asymmetric arrangement that enables direct wiring connection while controlling vibration characteristics. This asymmetric design allows the wiring to be directly connected to the electrodes without additional members, reducing device complexity while maintaining reliable reverberation characteristics through controlled asymmetric vibration modes.
2Force
If electrode extends to end edges in one direction, then vibration intensity increases, but spurious vibrations occur due to asymmetry
Solution Approach 1:
The patent applies local quality principle by creating non-uniform electrode spacing arrangements. The distance between the first electrode and second electrode in the first direction is different from the distance in the second direction, establishing different local vibration characteristics in different directions. This local quality variation allows the electrode to extend to end edges in one direction to maximize vibration intensity while the asymmetric spacing in orthogonal directions controls and reduces spurious vibrations by creating controlled vibration mode differences.
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 reduces spurious vibrations and shortens reverberation time, improving the sensor's reverberation characteristics and reception sensitivity by minimizing interference with desired resonant frequencies.
Implementation Method 1
The piezoelectric element includes a piezoelectric body, a first electrode, a second electrode, and a third electrode. The piezoelectric body includes a first surface and a second surface. The first surface is on the bottom portion side. The second surface is on a side opposite to the first surface. The first electrode is on the first surface. The second electrode is on the second surface. The second electrode is opposed to the first electrode with the piezoelectric body interposed therebetween.
Data Source
AI summary
An ultrasonic sensor includes a piezoelectric body including first and second surfaces. First and second electrodes are respectively provided on the first and second surfaces. The second electrode is opposed to the first electrode with the piezoelectric body interposed therebetween. A third electrode is provided on the second surface. The third electrode is spaced apart from the second electrode. The third electrode is electrically connected to the first electrode. When viewed from a thickness direction in which the first surface and the second surface are arranged, the second electrode extends to both end edges of the second surface in a first direction and is spaced apart from both end edges of the second surface in a second direction orthogonal to the first direction.