Micrometric Loudspeaker Linearization Springs
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Solution Overview
Problem
Micrometric loudspeakers face challenges in achieving satisfactory performance in terms of bandwidth and sound pressure level due to stiffening of flexible membranes and non-linear behaviors associated with piezoelectric actuators, which limit their integration into portable devices and compatibility with microfabrication processes.
Innovation Solution
A micrometric loudspeaker design incorporating a frame with a central crosspiece, two piezoelectric actuators, and elastic blades in a recessed-guided bending configuration, along with linearization springs to reduce longitudinal stresses and prevent stiffening, allowing for optimal flexibility and reduced geometric nonlinearities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the membrane guidance system is made more rigid for miniaturization, then the structural stability is improved, but the resonant frequency increases and bandwidth is reduced
Solution Approach 1:
The patent employs a flexible membrane instead of a rigid guidance system. The membrane's flexibility allows it to adapt to different vibration frequencies and modes, enabling the miniaturized loudspeaker to maintain wide bandwidth coverage (20 Hz to 20 kHz) despite the reduced structural rigidity inherent in miniaturized designs.
2Area of stationary object
If the surface area of the mechano-acoustic transducer is reduced for miniaturization, then the device size is reduced, but large displacement is required to achieve satisfactory sound pressure level
Solution Approach 1:
The patent changes the physical parameters of the membrane to optimize performance. By selecting specific material properties (density, elasticity) and geometric parameters (thickness, surface area), the membrane achieves sufficient displacement amplitude despite the reduced size. The membrane's flexibility compensates for the smaller surface area, allowing it to generate adequate sound pressure levels.
3Ease of manufacture
If flexible membranes are used in micrometric loudspeakers, then the manufacturing complexity is reduced, but geometric nonlinearities increase under deformation
Solution Approach 1:
The patent applies local quality by designing the membrane with specific regional characteristics. The membrane structure is optimized to maintain geometric linearity in the deformation zones most critical for sound generation, while other areas can accommodate greater flexibility. This localized optimization reduces geometric nonlinearities while preserving the manufacturing advantages of flexible membranes.
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 enhances sound pressure level and bandwidth performance by minimizing stiffening and non-linear behaviors, enabling better integration into portable devices and compatibility with microfabrication processes.
Implementation Method 1
Each piezoelectric actuator is associated with an elastic blade to induce, when it is electrically powered, a deformation of the elastic blade by bimetallic effect
Implementation Method 2
A mechanical-acoustic transducer, very often a membrane, converts this displacement into sound pressure
Data Source
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AI summary
Micrometer Loudspeaker The invention relates to a micrometer loudspeaker (1) comprising: • A frame (11), • An electromechanical transducer, and • A mechano-acoustic transducer comprising a rigid plate (131) movably mounted within the frame; the electromechanical transducer comprises two piezoelectric actuators (121a, 121b) and two elastic blades (122a, 122b); the frame comprises a central crossbar (111) from which the two blades extend until they engage two lateral coupling edges (132a, 132b) of the mechano-acoustic transducer; the mechano-acoustic transducer comprises two linearization springs (133a, 133b), each extending from one of the lateral edges to the rigid plate, to allow, during deformation of the blades, a displacement of the two lateral edges towards the central crossbar and reduce the longitudinal stresses applied to the blades during their deformation due to their "fixed-guided" bending configuration.The speaker delivers satisfactory performance, particularly in terms of bandwidth and/or sound pressure level produced.