Acceleration Sensor Anchor Placement for Zero Point Error Reduction
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Solution Overview
Problem
Mechanical stresses between the substrate and the web or seismic mass in acceleration sensors due to different thermal expansion coefficients and inherent stresses lead to zero point errors in capacitance measurements, as the weaker web and seismic mass deform, altering their position relative to the substrate.
Innovation Solution
An acceleration sensor design where the seismic mass is elastically suspended on multiple webs anchored outside the center of gravity, with anchors placed in proximity to minimize deflection and load distribution, allowing for reduced deformation and minimal influence on the relative orientation of the web and seismic mass with respect to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the web and seismic mass are manufactured with inherent stresses or subjected to thermal expansion differences, then mechanical stresses occur causing deformation, but this deformation leads to zero point errors in capacitance measurements
Solution Approach 1:
The patent converts the harmful mechanical stresses into a beneficial configuration by positioning anchors outside the center of gravity. This creates a moment arm that allows the stresses to be distributed as bending moments rather than causing direct deformation of the web-seismic mass connection, thereby eliminating zero point errors while utilizing the inherent stresses
Solution Approach 2:
The patent performs preliminary action by pre-positioning the anchors at specific locations outside the center of gravity during manufacturing. This pre-configured anchor placement ensures that when thermal expansion or inherent stresses occur during operation, the resulting deformations do not affect the relative position between the seismic mass and substrate, preventing zero point errors before they can occur
2Area of stationary object
If multiple anchors are provided close to the center of gravity, then space is saved on the substrate, but the relative orientation of the web and seismic mass becomes more sensitive to substrate deflection
Solution Approach 1:
The patent applies asymmetry by deliberately positioning the anchors outside the center of gravity rather than symmetrically around it. This asymmetric placement creates a stable configuration where the anchor arrangement forms a rigid triangular pattern with the center of gravity, making the web-seismic mass assembly resistant to substrate deflection while maintaining compact space usage
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 design minimizes zero point errors in capacitance measurements by reducing mechanical stresses and deformation, enabling more accurate acceleration sensing while optimizing space usage on the substrate.
Implementation Method 1
The seismic mass is situated on at least two sides of the web and is elastically suspended on the web
Implementation Method 2
The web is anchored on the substrate with the aid of an anchor
Data Source
AI summary
An acceleration sensor having a substrate, at least one web, and a seismic mass, the web and the seismic mass being situated over a plane of the substrate. The seismic mass is situated on at least two sides of the web and elastically suspended on the web. The web is anchored on the substrate with the aid of at least one anchor. At least one anchor is situated outside the center of gravity of the seismic mass.