MEMS Speaker Capsule Structure for Miniaturized Audio Output

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing miniaturized speakers for portable devices face challenges in achieving good audio performance with low distortion across the audible frequency range due to increased resonance frequency and reduced membrane surface, which limits acoustic pressure and integration into smaller devices.

Innovation Solution

A MEMS speaker design incorporating a bimetallic strip actuation system coupled with an amplification capsule, featuring a rigid central zone and flexible outer zone, enhances displacement and audio performance while being compatible with microfabrication techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the speaker is miniaturized to fit portable devices, then the device size is reduced, but the resonance frequency increases and bandwidth is reduced

Engineering Contradiction:

Improvespeaker sizeVSAvoidaudio performance quality

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The speaker is divided into distinct functional components: a fixed frame, a movable membrane, and a separately controllable actuation system. This segmentation allows independent optimization of each component's dimensions and properties, enabling miniaturization while maintaining performance through precise control of the actuation force applied to the membrane.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the actuation mechanism from traditional electromagnetic to electrostatic, which allows for different force-generation characteristics. By controlling the voltage applied to the actuation electrodes, the system can achieve the necessary membrane displacement with smaller dimensions, thereby reducing resonance frequency and maintaining bandwidth in miniaturized configurations.

Inventive Principle:

Principle #35Parameter changes

2Area of moving object

If the membrane surface is reduced for miniaturization, then the device fits better in portable devices, but the acoustic pressure radiated is reduced

Engineering Contradiction:

Improvemembrane surface areaVSAvoidacoustic pressure

Core Design Contradiction:

Area of moving objectVSStress or pressure

Solution Approach 1:

The actuation system applies a preliminary static force to the membrane through controlled voltage on the actuation electrodes, positioning the membrane in an optimal starting position. This preliminary action enables the membrane to achieve greater dynamic displacement during operation, compensating for the reduced surface area and maintaining acoustic pressure output in miniaturized speakers.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If electromagnetic transducers are used to achieve large membrane displacements, then audio performance is improved, but the speaker dimensions increase and microfabrication becomes incompatible

Engineering Contradiction:

Improvemembrane displacement capabilityVSAvoidmicrofabrication compatibility

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The invention replaces the electromagnetic actuation system with an electrostatic actuation system that is compatible with microfabrication processes. The electrostatic actuators can be directly integrated into the MEMS structure using standard semiconductor fabrication techniques, eliminating the need for separate magnetic components and enabling miniaturized, monolithic speaker production.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 MEMS speaker achieves improved displacement and acoustic pressure, maintaining audio quality and compatibility with miniaturized portable devices through microfabrication methods.

Implementation Method 1

A MEMS speaker design incorporating a bimetallic strip actuation system

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a second mechanical-acoustic transducer 20 that converts this displacement (Sm) into an acoustic pressure (Sa), that can be heard by the human ear 30

Methodology Applied

Scientific EffectAcoustic transduction: Acoustics

Data Source

PatentUS12528104B2MEMS speaker and method of microfabrication of such a speaker

Publication Date: 2026.01.20 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A MEMS speaker suitable for generating audible sound waves, includes a bimetallic strip actuation system extending in a first plane and an amplification capsule including a membrane extending in a second plane, parallel to the first plane, the membrane including a rigid interior zone and a flexible exterior zone, and a rigid coupling wall, fastened at the periphery of the bimetallic strip actuation system to make the exterior zone of the membrane integral with said actuation system.