Physical Quantity Sensor Recess Layout for Cross-Axis Sensitivity
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Solution Overview
Problem
Existing physical quantity sensors face issues with non-uniform moment of inertia due to recessed rotor and stators, leading to increased cross-axis sensitivity and reduced detection accuracy.
Innovation Solution
The sensor design incorporates a first recess in the movable electrode group, a second recess in the fixed electrode group, and a third recess in the frame unit to balance the mass distribution, ensuring uniform moment of inertia and reducing cross-axis sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rotor and stators are recessed to different depths, then the sensor structure can be optimized for detection, but the center of gravity balance is lost and cross-axis sensitivity increases
Solution Approach 1:
The patent introduces a counterweight portion in the rotor that compensates for the mass difference created by recessing the rotor and stators to different depths. This counterweight is positioned to balance the center of gravity of the movable body, thereby eliminating the cross-axis sensitivity while maintaining the detection accuracy benefits of the recessed structure.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the rotor. Specifically, certain regions of the rotor are recessed to different depths to optimize detection performance, while a counterweight portion is added to compensate for the mass distribution. This local differentiation allows the sensor to achieve both high detection accuracy and low cross-axis sensitivity.
2Adaptability or versatility
If the thickness of comb electrode is changed for each rotor, then the sensor can accommodate multiple stators, but the center of gravity balance is lost
Solution Approach 1:
The counterweight portion is specifically designed to compensate for the mass distribution changes caused by varying comb electrode thicknesses. By adjusting the mass and position of the counterweight, the center of gravity of the movable body is maintained at the desired location, enabling multi-stator compatibility without compromising stability.
Solution Approach 2:
The patent varies the thickness parameter of the comb electrodes for different rotors to accommodate multiple stators, while simultaneously adjusting the counterweight parameters (mass, position) to maintain center of gravity balance. This coordinated parameter adjustment allows the sensor to achieve versatility with multiple stators while preserving mechanical stability.
Data Source
AI summary
A physical quantity sensor detects a physical quantity in a third direction, and includes a fixer fixed to a substrate, a support beam having one end coupled to the fixer, and a movable body. The movable body includes a movable electrode unit and a frame unit. The fixed electrode unit includes a first fixed electrode group and a second fixed electrode group. The movable electrode unit includes a first movable electrode group and a second movable electrode group. A first recess recessed in the third direction is provided in the first movable electrode group, a second recess recessed in the third direction is provided in the second fixed electrode group, and a third recess recessed in the third direction is provided in a region of the frame unit on a second movable electrode group side.