Membrane MEMS Electroacoustic Transducer With Slit-Driven Displacement
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Solution Overview
Problem
Existing micro-speakers face challenges in achieving a balance between miniaturization, performance, and cost, with issues such as limited displacement at low frequencies, process variability, and unsuitability for SMT assembly due to membrane materials and structural asymmetry.
Innovation Solution
A microelectromechanical electroacoustic transducer design featuring a semiconductor membrane with symmetric central connection portions and slits, combined with piezoelectric actuators, which enhances displacement and maintains structural integrity and symmetry, allowing for high sound pressure levels and compatibility with SMT processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the membrane area is reduced for miniaturization, then the device size is reduced, but the sound pressure level decreases
Solution Approach 1:
The membrane is divided into multiple segments by introducing through slits, creating a multi-lobed structure that vibrates in different phases. This segmentation increases the overall displacement amplitude while maintaining a small membrane area, thereby preserving sound pressure level despite miniaturization.
Solution Approach 2:
The invention transitions from considering only the two-dimensional membrane area to utilizing the third dimension of displacement amplitude. By creating a multi-lobed structure with larger displacement amplitude through strategic slit placement, the system compensates for reduced area to maintain sound pressure output.
2Ease of operation
If the membrane is made discontinuous to increase displacement, then the yielding improves, but the response dynamics become non-constant across bandwidth
Solution Approach 1:
The through slits are positioned asymmetrically relative to the membrane center, creating a specific multi-lobed vibration pattern. This asymmetric placement optimizes the vibration modes to maintain consistent response dynamics across the audio bandwidth while achieving the necessary displacement amplitude.
Solution Approach 2:
The invention carefully controls the geometric parameters of the through slits (width, length, position) to optimize the membrane's vibration characteristics. By adjusting these parameters, the system achieves both high yielding and consistent response dynamics across the full audio bandwidth.
3Ease of operation
If the membrane is made discontinuous with cantilever structures, then the displacement increases, but process variability affects performance
Solution Approach 1:
The through slits serve multiple functions simultaneously: they create the necessary membrane discontinuity for high displacement, defines the vibration lobes for consistent response, and provide self-alignment features that reduce sensitivity to manufacturing variations. This multi-functionality makes the design more robust to process variability.
4Ease of operation
If polymeric membrane is used for high yielding, then the response improves, but the device cannot withstand soldering temperatures
Solution Approach 1:
The invention changes the material parameter from polymeric to semiconductor material, while compensating for the typically lower yielding of semiconductor materials through structural design (through slits creating multi-lobed vibration). This allows the membrane to withstand high soldering temperatures while maintaining adequate displacement through geometric optimization.
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 improved sound pressure levels, especially at low frequencies, while reducing process variability and enabling miniaturization without compromising audio quality and assembly compatibility.
Implementation Method 1
a piezoelectric actuator on a peripheral portion of the membrane
Data Source
AI summary
A microelectromechanical electroacoustic transducer includes a supporting frame of semiconductor material, a membrane of semiconductor material, connected to the supporting frame along a perimeter and having central symmetry, and a piezoelectric actuator on a peripheral portion of the membrane. The membrane has through slits of elongated shape arranged around a center of the membrane.