Acoustic Membrane Array Spacing for Lamb Wave Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic arrays face challenges with mechanical cross-talk between adjacent acoustic membranes on thin substrates, which can diminish performance and require additional insulation or increased spacing, leading to bulkier designs and higher fabrication costs.
Innovation Solution
The design optimizes the distance between adjacent acoustic membranes on a thin substrate such that lamb waves generated at the resonance frequency arrive in-phase, enhancing actuation and minimizing cross-talk. This is achieved by determining the lamb wavelength and adjusting the membrane distances to be an integer multiple of the wavelength, allowing for a densely packed array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic insulation is added between transducers to avoid cross-talk, then cross-talk is reduced, but fabrication cost increases and device becomes bulkier
Solution Approach 1:
The patent changes the spacing parameter between transducers to specific values (integer multiples of lambda/2) that transform the harmful lamb waves into beneficial constructive interference patterns, eliminating the need for additional insulation structures
Solution Approach 2:
The patent converts the harmful mechanical cross-talk caused by lamb waves into a beneficial effect by spacing transducers at distances where lamb waves arrive in-phase, causing constructive interference that enhances rather than degrades performance
2Object-affected harmful factors
If distance between transducers is increased to avoid cross-talk, then cross-talk is reduced, but the number of transducers that can fit on a given surface decreases
Solution Approach 1:
The patent optimizes the spacing parameter to specific discrete values (integer multiples of lambda/2) that simultaneously achieve cross-talk reduction and maximize transducer density by preventing harmful interference while allowing close packing
3Length of stationary object
If transducers are densely packed on a thin substrate, then device thickness is reduced and flexibility is improved, but mechanical cross-talk between adjacent transducers increases
Solution Approach 1:
The patent changes the spacing parameter between transducers to specific multiples of lambda/2, which transforms the propagation characteristics of lamb waves on the thin substrate from harmful to beneficial, enabling dense packing without cross-talk
Solution Approach 2:
The patent employs a periodic spacing pattern where transducers are positioned at regular intervals corresponding to integer multiples of lambda/2, creating a systematic arrangement that ensures lamb waves from adjacent transducers always arrive in-phase
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 approach enables the creation of densely packed acoustic arrays with reduced cross-talk, maintaining performance while minimizing design bulk and fabrication costs, and allowing for flexible, thin substrates.
Implementation Method 1
a main source of mechanical cross-talk between adjacent acoustic membranes on a relatively thin substrate or foil can be traced to anti-symmetrical lamb waves travelling through an intermediate section of such substrate
Implementation Method 2
the lamb waves, generated at the resonance frequency of the membranes
Data Source
AI summary
An acoustic device (100) comprises an array of acoustic membranes (1, 2, 3, 4) formed on a foil (10). Each of the acoustic membranes (1, 2, 3, 4) is configured to vibrate at a resonance frequency (Fr) of the acoustic membranes (1, 2, 3, 4) for generating respective acoustic waves (W1,W2,W3,W4). Relative phases (ΔΦ12,ΔΦ34) are determined at which the acoustic membranes (1, 2, 4, 5) are actuated for generating a predetermined interference pattern (C) between the acoustic waves (W1,W2,W3,W4). A lamb wavelength (As) is determined of lamb waves (Ws) at the resonance frequency (Fr) travelling through intermediate sections (lOi, lOj) of the foil (10) between adjacent acoustic membranes (1,2; 3,4). Distances (X12,X34) of the intermediate sections (10i, 10j) between the adjacent acoustic membranes (1,2; 3,4) in the layout are determined in accordance with the relative phases (ΔΦ12,ΔΦ34) and the lamb wavelength (λs) for having the lamb waves (Ws), generated by one acoustic membrane (1,3), arrive in phase with an adjacent acoustic membrane (2,4).