Electroacoustic Transducer Nodal Ring for Uniform Sound Radiation
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Solution Overview
Problem
Conventional electroacoustic transducers with a concave diaphragm design suffer from non-uniform sound transmission as a function of angle due to direct attachment of piezoceramic devices, leading to energy loss and interference from anti-phase vibrations, compromising their performance in applications requiring wide-angle uniform radiation patterns.
Innovation Solution
An electroacoustic transducer design featuring a cylindrical vibratory component with a planar top wall and outwardly directed base portion, where the housing's inwardly directed lip forms a seal with the vibratory component's corner, creating a nodal ring and shielding anti-phase vibrations, ensuring uniform sound radiation and environmental robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a piezoceramic device is attached directly to the underside of the vibratory diaphragm, then the transducer can be manufactured with a simple structure, but the sound transmission becomes non-uniform as a function of angle due to anti-node vibrations creating lobes in the radiation pattern
Solution Approach 1:
The patent introduces a vibratory component with a nodal ring as an intermediary between the piezoceramic transducer and the external environment. This nodal ring acts as a mediator that prevents anti-node vibrations from radiating sound laterally, thereby eliminating lobes in the radiation pattern while maintaining the simple direct-attachment structure. The vibratory component with its specific nodal characteristics serves as the buffering intermediary that resolves the contradiction between structural simplicity and transmission uniformity.
2Manufacturing precision
If the diaphragm surface is made concave to increase thickness at the periphery for precise resonant frequency adjustment, then resonant frequency precision is improved, but energy is lost into the housing and anti-phase vibrations interfere with sound transmission
Solution Approach 1:
The patent segments the vibratory system into distinct functional zones: a vibratory component with specific geometry (cylindrical side wall, planar top wall, outwardly directed base portion) that creates a nodal ring, separating the regions of constructive and destructive interference. This segmentation isolates the anti-phase vibrations within the housing structure while directing energy through the nodal ring toward the desired radiation direction, thereby reducing energy loss into the housing while maintaining resonant frequency precision.
Solution Approach 2:
The patent applies local quality by creating a specific geometric configuration of the vibratory component with a nodal ring at a particular location. The nodal ring creates localized regions of different vibration characteristics: the top wall radiates sound constructively while the side wall portions in anti-phase are shielded by the housing. This local differentiation of vibration modes at specific locations resolves the energy loss problem while preserving the resonant frequency adjustment capability.
3Ease of manufacture
If a conventional flat diaphragm surface is used, then manufacturing is simpler, but resonant frequency adjustment is critically dependent on the amount of material removed, reducing precision
Solution Approach 1:
The patent employs a vibratory component with a cylindrical side wall and curved geometry rather than a completely flat diaphragm. This curvature provides a more favorable geometric basis for resonant frequency adjustment through material removal, as the cylindrical form allows for more predictable and less critical material removal while maintaining structural integrity and acoustic performance. The curved geometry simplifies manufacturing compared to precision flat surfaces while improving frequency adjustment 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
The design achieves a uniform radiation pattern over a wide angle, reducing energy loss and interference, making it suitable for applications like anemometers, and allows for a rugged, waterproof construction.
Implementation Method 1
at least one piezoelectric element
Implementation Method 2
the flexural-mode of the vibratory component then being such that a nodal ring is created when the electroacoustic transducer is in use
Implementation Method 3
generating a directional beam
Data Source
Figure 1
Figure 2~3
AI summary
An electroacoustic transducer comprising an electromechanical transducer (12) and a vibratory component (36). The latter has a generally cylindrical side wall (38), an outwardly directed portion (40) at the base of the side wall (38), and a generally planar vibratory top wall (42) extending inwardly from the rim of the side wall (38) further from its base to close the upper end of the cylindrical side wall (38). The said outwardly directed portion (40) is mounted on the electromechanical transducer (12).