Ultrasonic Sensor Acoustic Matching Layer Segmentation
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Solution Overview
Problem
Ultrasonic sensors face issues with low propagation efficiency of ultrasonic waves and leakage currents due to improper design, leading to inaccurate detection and safety concerns, particularly in applications requiring high detection accuracy and electrical safety.
Innovation Solution
The ultrasonic sensor design features an air layer opposite the vibrating plate and piezoelectric element, increasing the contact area with the acoustic matching layer to enhance wave propagation and reduce leakage currents, while a partition wall between units suppresses residual vibration, improving detection accuracy and electrical safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an acoustic matching layer is provided around the piezoelectric element, then ultrasonic wave propagation is improved, but leakage current is generated
Solution Approach 1:
The acoustic matching layer is segmented into two distinct regions: a first acoustic matching layer in contact with the piezoelectric element, and a second acoustic matching layer in contact with the vibration plate. This segmentation allows the first layer to provide acoustic coupling while the second layer manages vibration, preventing leakage current paths through the piezoelectric element.
Solution Approach 2:
The first acoustic matching layer acts as an intermediary between the piezoelectric element and the second acoustic matching layer. It provides the necessary acoustic coupling for ultrasonic wave propagation while preventing direct contact between the piezoelectric element and the vibration plate, thereby eliminating the leakage current path.
2Loss of energy
If the vibration plate area is increased to improve ultrasonic wave transmission, then propagation efficiency is improved, but residual vibration increases
Solution Approach 1:
The acoustic matching layer is divided into functional segments: the first layer handles piezoelectric element coupling, and the second layer manages vibration plate contact. This segmentation allows the vibration plate to have sufficient area for efficient ultrasonic transmission while the second acoustic matching layer provides vibration damping to reduce residual vibrations.
3Area of stationary object
If the piezoelectric element is surrounded by acoustic matching layer, then detection coverage is improved, but detection accuracy decreases due to leakage current
Solution Approach 1:
The acoustic matching structure is segmented into two layers with distinct functions. The first layer provides localized acoustic coupling for detection, while the second layer extends the detection coverage area without creating leakage current paths, thereby maintaining detection accuracy while improving coverage.
Solution Approach 2:
The first acoustic matching layer serves as an intermediary that enables detection coverage extension through the second layer while preventing leakage current. This intermediary structure allows the piezoelectric element to detect targets over a wider area without compromising measurement precision.
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 significantly enhances the propagation efficiency of ultrasonic waves and reduces leakage currents, resulting in improved detection accuracy and electrical safety, enabling precise target identification and safer operation.
Implementation Method 1
a piezoelectric element (300) which is provided on a first surface (50b) of the vibration plate (50)
Implementation Method 2
the space (S) is filled with an acoustic matching layer (20) from which the ultrasonic wave is to be transmitted to a measuring target
Implementation Method 3
a reflection layer (71) that is to reflect other ultrasonic waves which are transmitted in a different direction from a transmitted ultrasonic wave transmitted to a measuring target side
Implementation Method 4
the ultrasonic wave reflected by the detection target and received by the ultrasonic sensor unit
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
To provide an ultrasonic sensor that can improve propagation efficiency of an ultrasonic wave, an ultrasonic sensor 1 comprises a substrate 10 where an opening section W is formed; a vibration plate 50 provided on the substrate 10 so as to close the opening section; a piezoelectric element 300 provided on a surface of the vibration plate 50 on an opposite side to the opening section W and having a first electrode 60, a piezoelectric material layer 70, and a second electrode 80; and a reflection layer 71 provided in a space around the piezoelectric element 300 on the surface of the vibration plate on an opposite side to the opening section, to reflect other ultrasonic waves transmitted in a different direction from a transmitted ultrasonic wave transmitted to a measuring target side on an interface between the piezoelectric element and the reflection layer, and having a thickness so as to superimpose other ultrasonic waves on the transmitted ultrasonic wave.