Flexible PCB Microphone Arrays for 3D Beamforming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional microphone arrays are limited by rigid PCB technology to planar geometries, which restricts the design of directional microphone arrays and fails to effectively combat background noise in mobile applications, especially when the signal-to-noise ratio (SNR) falls below 5 dB.
Innovation Solution
The use of flexible printed circuit boards (PCBs) to mount surface-mount MEMS or electret microphone devices, allowing for more general microphone array geometries and combining multiple devices to enhance signal-to-noise ratio through beamforming, where the signals from multiple devices are summed to form a new microphone signal, effectively dealing with thermal noise and achieving improved noise rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional rigid PCB technology is used to mount microphone devices, then the manufacturing process is simple and reliable, but the array geometry is limited to planar configurations
Solution Approach 1:
The patent applies flexible PCB technology to replace conventional rigid PCBs, enabling the microphone array to achieve non-planar geometries such as cylindrical, spherical, and arbitrary 3D configurations. The flexible substrate allows the array manifold to be formed in three-dimensional space while maintaining the simplicity of surface-mount manufacturing processes.
Solution Approach 2:
The invention transitions from two-dimensional planar array configurations constrained by rigid PCBs to three-dimensional spatial arrangements enabled by flexible PCBs. This dimensional change allows microphone elements to be positioned in complex geometries that exploit spatial diversity for improved noise rejection and directional sensitivity.
2Reliability
If more microphone devices are combined to enhance signal-to-noise ratio through beamforming, then the noise rejection improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple surface-mount microphone devices on a flexible PCB to form a microphone array that performs beamforming. By merging the signals from multiple microphones through the flexible interconnect, the system achieves improved signal-to-noise ratio and noise rejection while maintaining a compact form factor that would be difficult to achieve with rigid structures.
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
This approach enables the creation of high-quality, professional-grade directional microphone arrays with improved noise rejection and immunity to background noise, achieving a gain in signal-to-noise ratio and allowing for more flexible array geometries, such as cylindrical, spiral, and polyhedral configurations.
Implementation Method 1
mounting microphone devices on flexible PCBs that are now used in miniaturized product design and as interconnects in complex multi-board systems, to allow more-general microphone array geometries
Implementation Method 2
combining multiple devices to enhance signal-to-noise ratio through beamforming, where the signals from multiple devices are summed to form a new microphone signal, effectively dealing with thermal noise and achieving improved noise rejection
Data Source
AI summary
A microphone array, having a three-dimensional (3D) shape, has a plurality of microphone devices mounted onto (at least one) flexible printed circuit board (PCB), which is bent to achieve the 3D dimensional shape. Output signals from the microphone devices can be combined (e.g., by weighted or unweighted summation or differencing) to form sub-element output signals and/or element output signals, and ultimately a single array output signal for the microphone array. The PCB may be uniformly flexible or may have rigid sections interconnected by flexible portions. Possible 3D shapes include (without limitation) cylinders, spirals, serpentines, and polyhedrons, each formed from a single flexible PCB. Alternatively, the microphone array may be an assembly of multiple, interconnecting sub-arrays, each having two or more rigid portions separated by one or more flexible portions, where each sub-array has at least one cut-out portion for receiving a rigid portion of another sub-array.