Vibration Sensor Venting for EMI Shielding and Sensitivity
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Solution Overview
Problem
Current vibration sensors for handheld and wearable electronic devices face challenges in achieving high signal-to-noise ratios due to inadequate design for electromagnetic interference (EMI) shielding and sensitivity.
Innovation Solution
A vibration sensor design featuring a circuit board, a pressure-enhancing member with a diaphragm and mass, and a metal housing that defines multiple chambers, where the air-containing volume of the first chamber is smaller than the third chamber, allowing for improved air damping and EMI shielding, enhancing sensitivity and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air-containing volume of the first chamber is increased to improve sensitivity, then the sensitivity improves, but the air damping decreases and frequency response becomes less smooth
Solution Approach 1:
The patent divides the internal space into multiple chambers (first chamber, second chamber, third chamber) with different air-containing volumes. The first chamber has a smaller volume optimized for air damping and frequency response, while the third chamber has a larger volume. This segmentation allows each chamber to serve different functional purposes, resolving the contradiction between sensitivity and frequency response smoothness.
Solution Approach 2:
Different chambers are designed with different air-containing volumes tailored to their specific functions. The first chamber near the diaphragm has a smaller volume to provide adequate air damping, while the third chamber has a larger volume. This local optimization of chamber volumes allows the system to achieve both good frequency response and adequate sensitivity without compromising either parameter.
2Object-affected harmful factors
If the metal housing is added to improve EMI shielding, then the EMI shielding improves, but the device complexity increases
Solution Approach 1:
The metal housing serves multiple functions simultaneously: it provides EMI shielding, defines the third chamber, offers mechanical support, and protects internal components. By combining multiple functions into a single component, the patent achieves effective EMI shielding without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the EMI shielding function with the structural housing that defines the third chamber. Instead of adding a separate shielding layer, the housing itself is made of metal to provide both structural integrity and electromagnetic interference protection, thereby reducing overall device complexity while achieving dual benefits.
3Measurement precision
If the pressure-enhancing member with mass is added to improve sensitivity, then the sensitivity improves, but the device complexity increases
Solution Approach 1:
The patent combines the pressure-enhancing member with the diaphragm assembly, where the mass is integrated onto the diaphragm or its supporting structure. This merging of the pressure-enhancing function with the existing diaphragm structure improves sensitivity without adding a completely separate complex subsystem.
Solution Approach 2:
The patent modifies the physical parameters of the existing diaphragm structure by adding mass to the pressure-enhancing member, which changes the dynamic characteristics and improves sensitivity. This parameter modification approach allows sensitivity enhancement without requiring a complete redesign of the sensing structure.
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 effectively increases the sensitivity of the vibration sensor and achieves a higher signal-to-noise ratio by improving air damping and shielding against electromagnetic interference, meeting the performance requirements for modern electronic devices.
Implementation Method 1
When the pressure-enhancing member moves to squeeze the air in the second chamber, the sensitivity of the pressure sensing device will be greatly improved... an air-containing volume of the first chamber is smaller than that of the third chamber, which helps to increase air damping below the diaphragm
Implementation Method 2
The metal housing covers the pressure-enhancing member and the pressure sensing device. Under the shielding of the metal housing, the pressure sensing device is more effective against electromagnetic interference (EMI)
Implementation Method 3
The pressure-enhancing member includes a diaphragm and a mass... When the pressure-enhancing member moves to squeeze the air in the second chamber, the sensitivity of the pressure sensing device will be greatly improved
Data Source
AI summary
A vibration sensor is designed to have a pressure-enhancing member, a pressure sensing device and first, second, third chambers. An air gap is designed to enable the first chamber to be vented to the third chamber such that the first chamber is combined with the third chamber to obtain a communicable air volume. An adhesive layer is formed between a spacer and a circuit board, and the air gap is formed in an adhesive-absent section between the spacer and the circuit board. When the pressure-enhancing member is moved to squeeze the air in the second chamber, a sensitivity of the pressure sensing device will be greatly improved.