Micro Speaker Acoustic Mesh for Ultra-High-Frequency SPL
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Solution Overview
Problem
Traditional moving coil speakers have a large size and there is a need to reduce their size while maintaining or improving sound pressure level (SPL) performance, particularly in ultra-high frequency bands above 20 kHz, which is compromised by Helmholtz resonance in the back side hollow chamber.
Innovation Solution
A micro speaker structure with a substrate, diaphragm, coil, circuit board, and acoustic mesh is designed, where the acoustic mesh covers vent holes on the circuit board to reduce the resonant frequency of the back side hollow chamber, using multiple layers and magnetic elements to enhance sound performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional moving coil speakers are used, then sound pressure level performance is maintained, but device size becomes large and occupies much space
Solution Approach 1:
The patent replaces the traditional mechanical moving coil speaker structure with a micro-electromechanical system (MEMS) based speaker structure. This substitution enables significant size reduction while maintaining acoustic performance through integrated micro-scale components including a diaphragm, coil, and magnetic element fabricated using semiconductor processing techniques
Solution Approach 2:
The patent employs a nested structure where the coil is embedded within the diaphragm, and the magnetic element is positioned within the hollow chamber formed by the substrate. This nesting arrangement maximizes space utilization and enables compact integration of multiple functional components in a miniaturized speaker structure
2Productivity
If micro speaker size is reduced using MEMS process, then manufacturing scalability is improved, but sound pressure level performance in ultra-high frequency bands deteriorates due to Helmholtz resonance
Solution Approach 1:
The patent changes the physical parameters of the acoustic system by introducing an acoustic mesh with specific pore sizes (0.1-20 μm) and controlling the hollow chamber volume. These parameter adjustments modify the Helmholtz resonance frequency to achieve improved sound pressure level performance in ultra-high frequency bands while maintaining miniaturized dimensions
Solution Approach 2:
The patent introduces an acoustic mesh as an intermediary component between the hollow chamber and the external environment. This mesh structure with controlled pore characteristics acts as a mediator to manage acoustic pressure and reduce Helmholtz resonance effects, thereby improving ultra-high frequency sound pressure level performance
3Reliability
If acoustic mesh with small pores is used to reduce Helmholtz resonance, then sound pressure level performance in ultra-high frequency bands is improved, but acoustic mesh complexity increases
Solution Approach 1:
The patent employs a porous acoustic mesh material with precisely controlled pore sizes in the range of 0.1-20 micrometers. This porous structure provides the necessary acoustic filtering function to reduce Helmholtz resonance while maintaining a relatively simple overall device architecture, avoiding the need for complex multi-component acoustic management systems
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 micro speaker structure achieves improved sound pressure level (SPL) performance in ultra-high frequency bands by reducing the resonant frequency drop, enhancing frequency response and reliability through the use of acoustic meshes and magnetic elements.
Implementation Method 1
the requirements for the sound pressure level (SPL) performance of micro speakers in the ultra-high frequency bands (e.g., above 20 kHz) have become increasingly higher
Implementation Method 2
The acoustic mesh has a plurality of pores to allow sound to pass through, and the pores are smaller than the vent hole
Implementation Method 3
The coil is embedded in the diaphragm
Implementation Method 4
The micro speaker structure further includes a first permanent magnetic element disposed on the top surface of the circuit board and in the hollow chamber
Data Source
AI summary
A micro speaker structure is provided. The micro speaker structure includes a substrate, a diaphragm, a coil, a circuit board, and at least one acoustic mesh. The substrate has a hollow chamber. The diaphragm is disposed over the substrate and covers the hollow chamber. The coil is embedded in the diaphragm. The circuit board is attached to the substrate, wherein at least one vent hole passes through the top surface and the bottom surface of the circuit board. The acoustic mesh is disposed on the bottom surface of the circuit board to cover the vent hole. The acoustic mesh has a plurality of pores to allow sound to pass through, and the pores are smaller than the vent hole.