Micro Speaker Diaphragm Thinning for Higher SPL and Strength
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Solution Overview
Problem
Traditional moving coil speakers are large in size and occupy significant space, and existing MEMS processes for reducing their size do not adequately address performance enhancement needs.
Innovation Solution
A micro speaker structure with a diaphragm featuring a locally thinner region formed by an etching pattern, embedded coil, and magnetic elements, along with a method for fabrication that includes etch stop layers and patterned dielectric layers to protect the coil during etching, enhancing diaphragm elasticity and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diaphragm thickness is reduced to increase elasticity and sensitivity, then the sensitivity and sound pressure level are improved, but the mechanical strength is compromised
Solution Approach 1:
The patent applies local quality by creating an etching pattern with varying thickness across the diaphragm surface. The diaphragm has a first region with greater thickness for mechanical strength and a second region with lesser thickness for enhanced elasticity and sensitivity. This non-uniform thickness distribution allows different parts of the diaphragm to serve different functions, resolving the contradiction between overall strength and localized sensitivity.
2Reliability
If the diaphragm thickness is uniformly reduced to enhance elasticity, then the sensitivity is improved, but the coil protection during etching becomes difficult
Solution Approach 1:
The patent applies preliminary action by forming the etching pattern and protective layers before completing the coil structure. The etching pattern is created in the diaphragm material first, then the coil is formed over this patterned surface. This sequence allows the etching process to be completed before the coil is in place, eliminating the need to protect the coil during etching while still achieving the desired sensitivity enhancement.
3Strength
If traditional moving coil speaker design is used, then the mechanical strength is maintained, but the size is large and occupies significant space
Solution Approach 1:
The patent applies parameter changes by transitioning from traditional macro-scale moving coil speaker dimensions to micro-scale dimensions enabled by MEMS technology. The diaphragm thickness is reduced from traditional millimeter-scale to micrometer-scale (with varying thickness across regions), and the overall speaker volume is dramatically reduced while maintaining adequate mechanical strength through the strategic thickness variation and structural design.
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 sensitivity and sound pressure level through increased diaphragm elasticity, leveraging a locally thinner etching pattern and multi-layered coil design, while maintaining mechanical strength.
Implementation Method 1
The micro speaker structure achieves improved sensitivity and sound pressure level through increased diaphragm elasticity
Implementation Method 2
The micro speaker structure includes a coil, a carrier board, and a first permanent magnetic element
Data Source
AI summary
A micro speaker structure is provided, including a substrate, a diaphragm, a coil, a carrier board, and a permanent magnetic element. The substrate has a hollow chamber. The diaphragm is disposed over the substrate and covers the hollow chamber. The diaphragm includes an etching pattern recessed form a first surface of the diaphragm. Etching patterns are used to increase sound pressure level at special frequency range. The coil is embedded in the diaphragm. The carrier board is disposed on the bottom surface of the substrate. The permanent magnetic element is disposed on the carrier board and in the hollow chamber. The first surface of the diaphragm faces the permanent magnetic element.