Moving-Member Hole Patterns Balance Damping and Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acceleration sensors face a drop in sensitivity due to reduced electrostatic capacitance and increased air resistance caused by penetration holes and air resistance when the moving member swings, making it difficult to achieve both high sensitivity and low damping.
Innovation Solution
The design of the physical quantity sensor includes a moving member with penetration holes arranged in a specific pattern to minimize damping while maintaining sensitivity, where the occupancy rate of the holes is optimized to achieve equal hole damping and squeeze film damping, ensuring a high sensitivity of detection and reduced damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If penetration holes are formed in the moving member, then damping is reduced, but sensitivity of detection drops due to reduced electrostatic capacitance
Solution Approach 1:
The moving member is designed with non-uniform penetration hole distribution, where the occupancy rate of penetration holes varies in different regions. Specifically, the occupancy rate in the first area is different from that in the second area, allowing local optimization of damping reduction while maintaining electrostatic capacitance for sensitivity.
Solution Approach 2:
The invention optimizes the occupancy rate parameter of penetration holes to achieve a balance between damping reduction and sensitivity maintenance. By carefully controlling the occupancy rate within specific ranges, the design achieves minimal damping while preserving sufficient electrostatic capacitance for accurate detection.
2Object-generated harmful factors
If penetration holes are increased to reduce damping, then air resistance decreases, but electrostatic capacitance is reduced
Solution Approach 1:
Different regions of the moving member have different penetration hole occupancy rates. The first area and second area are designed with different hole densities, allowing the structure to reduce air resistance in regions where it benefits damping while preserving electrostatic capacitance in regions critical for detection.
Solution Approach 2:
The moving member is segmented into multiple areas with different penetration hole configurations. This segmentation allows independent optimization of each region's properties, enabling the overall structure to achieve both low air resistance and sufficient electrostatic capacitance through coordinated design of different segments.
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 effectively reduces damping while maintaining a high sensitivity of detection, allowing for accurate acceleration measurement by balancing the design of penetration holes to achieve minimal damping and sufficient sensitivity.
Implementation Method 1
μ is a viscous resistance of a gas in the gap, and C is a damping generated in the moving member
Implementation Method 2
a fixed detection electrode arranged at the substrate and detecting an electrostatic capacitance generated between the moving member and the fixed detection electrode
Implementation Method 3
When an acceleration is applied from a direction in which the moving member and the fixed detection electrode overlap each other, the moving member swings about the beam as an axis of rotation
Data Source
AI summary
A physical quantity sensor includes a substrate, and a moving member facing the substrate in a third direction via a gap and becoming displaced in the third direction in relation to the substrate. The moving member has a first part and a second part, and a plurality of penetration holes arranged at the first part and the second part and penetrating the moving member in the third direction. In at least one of a first area overlapping the first part and a second area overlapping the second part, as viewed in a plan view from the third direction, C≤1.5×Cmin is satisfied, where C is a damping and Cmin is a minimum value of the damping.