Capacitive Inertial Sensor Layout With Internal Dampers for Miniaturization
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Solution Overview
Problem
Existing physical quantity sensors, such as those described in JP-T-2021-524035, face challenges with increased size due to the placement of damping plates outside the proof mass, which hinders miniaturization while maintaining accurate detection.
Innovation Solution
The proposed physical quantity sensor incorporates damper units within the movable body, utilizing a compact design that includes damper units inside the movable body to damp vibrations and prevent cross-axis sensitivity, while incorporating a reinforcer to maintain structural integrity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If damper units are provided outside the proof mass, then vibration damping is achieved, but the sensor size increases
Solution Approach 1:
The damper units are nested inside the movable body structure, specifically positioned within the region surrounded by the support beam and frame unit. This internal placement allows the damper to function within the existing sensor footprint without requiring additional external space, thereby achieving vibration damping while preventing sensor size increase
Solution Approach 2:
The damper units are positioned in a region surrounded by the support beam and frame unit, utilizing the internal three-dimensional space of the movable body. This spatial arrangement allows the damper to be integrated within the existing structure rather than adding to external dimensions, effectively using internal volume to achieve damping functionality
2Volume of moving object
If sensor size is reduced for miniaturization, then compactness is achieved, but cross-axis sensitivity increases
Solution Approach 1:
The patent replaces mechanical reinforcement methods with electrostatic force fields generated by the fixed and movable electrodes. These electrostatic forces provide the necessary mechanical support and stability to maintain low cross-axis sensitivity without requiring additional mechanical structures that would increase sensor size
Solution Approach 2:
The patent optimizes electrical parameters including electrode spacing, electrode area, and drive voltage to achieve the desired mechanical stability and cross-axis sensitivity performance. By adjusting these electrical parameters, the system maintains measurement precision in miniaturized configurations without requiring proportional increases in physical dimensions
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 configuration allows for miniaturization of the sensor while maintaining high detection accuracy and reducing cross-axis sensitivity, enabling efficient detection of physical quantities like acceleration in multiple directions.
Implementation Method 1
a damper unit coupled to the frame unit, provided in a region surrounded by the support beam and the frame unit, and configured to damp vibration of the frame unit in the first direction
Implementation Method 2
the movable electrode unit including a movable electrode facing the fixed electrode of the fixed electrode unit
Data Source
AI summary
A physical quantity sensor includes an anchor fixed to a substrate, a support beam, a fixed electrode unit, a movable body, and a damper unit. The fixed electrode unit is provided at the substrate. One end of the support beam is coupled to the anchor. The movable body includes a movable electrode unit and a frame unit. The movable electrode unit includes a movable electrode facing a fixed electrode of the fixed electrode unit. The frame unit couples the movable electrode unit and the other end of the support beam. The damper unit is coupled to the frame unit, is provided in a region surrounded by the support beam and the frame unit, and damps vibration of the frame unit in a first direction.