Triaxial Acceleration Sensor Rocker Mass Design
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Solution Overview
Problem
Conventional triaxial acceleration sensors require large space due to separate seismic masses for each direction, making them less compact and efficient for applications in entertainment and automotive electronics.
Innovation Solution
A triaxial micromechanical acceleration sensor design utilizing a rocker mass connected via z and x-y springs, allowing detection of accelerations in all three spatial directions with a single mass element, enabling a compact arrangement by using grid and substrate electrodes for differential analysis of deflections and rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three separate seismic masses are used for detecting accelerations in all three spatial directions, then measurement precision is improved, but device area increases significantly
Solution Approach 1:
The patent merges three separate seismic masses into a single integrated mass element that can detect accelerations in all three spatial directions. This mass element is connected to the substrate through multiple spring systems (x-springs, y-springs, and z-springs) that enable independent movement and detection in each direction, thereby reducing the overall sensor area while maintaining measurement capability.
Solution Approach 2:
The single mass element serves multiple functions by being capable of detecting accelerations in x, y, and z directions simultaneously. The spring systems connect this universal mass element to the substrate in a way that allows it to respond to forces from all three spatial directions, making one mass element perform the work of three separate masses.
2Measurement precision
If three independent sensor cores with separate seismic masses are implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines three independent sensor cores into a single integrated structure where one mass element is connected to the substrate through multiple spring systems. This merging reduces the number of separate components while maintaining the ability to measure accelerations in all three directions through a unified detection mechanism.
Solution Approach 2:
The single mass element is segmented into different functional regions through the spring systems, with x-springs, y-springs, and z-springs providing independent movement paths for each spatial direction. This segmentation allows the unified mass element to be analyzed differentially for each direction while reducing overall structural complexity compared to three separate masses.
3Area of stationary object
If a single mass element is used for detecting accelerations in all three spatial directions, then device area is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent employs dynamic spring systems (x-springs, y-springs, z-springs) that enable the single mass element to move dynamically in response to accelerations in different directions. The spring systems provide the necessary degrees of freedom for the mass element to respond accurately to forces from x, y, and z directions, maintaining measurement precision through dynamic response rather than static structure.
Solution Approach 2:
The patent utilizes differential evaluation of capacitance changes from multiple electrode pairs to detect the orientation and position of the mass element. By comparing signals from different electrode pairs (e.g., first and second electrode pairs for x-direction, third and fourth for y-direction), the system achieves feedback-based precision in determining acceleration direction and magnitude, compensating for the limitations of a single mass element.
4Measurement precision
If grid electrodes and substrate electrodes are used for differential analysis, then zero deviation compensation is improved, but device complexity increases
Solution Approach 1:
The electrode system is segmented into multiple pairs (first electrode pair, second electrode pair for x-direction; third electrode pair, fourth electrode pair for y-direction; first and second electrode pairs for z-direction). Each pair forms a capacitor with the mass element, allowing differential evaluation to compensate for zero deviations. This segmentation enables systematic compensation while organizing complexity into manageable functional groups.
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 achieves a highly compact configuration while maintaining accurate detection of accelerations in all directions, reducing size and improving zero deviation compensation.
Implementation Method 1
a z spring connected to the rocker mass, which allows the rocker mass to rotate about an axis
Implementation Method 2
at least one additional spring system connected to the substrate and the rocker mass. The additional spring system allows the rocker mass to deflect in an x or y direction
Implementation Method 3
The seismic mass and the stationary electrodes form one or more capacitors. A deflection of the seismic mass caused by an acceleration acting on the micromechanical acceleration sensor results in a change in the capacitances of these capacitors
Implementation Method 4
At least one z electrode, fixedly connected to the substrate, may be situated opposite to the rocker mass which allows a detection of a rotation of the rocker mass
Data Source
AI summary
An acceleration sensor includes a substrate, a rocker mass, a z spring connected to the rocker mass, which allows the rocker mass to rotate about an axis, and at least one additional spring system connected to the substrate and the rocker mass. The additional spring system allows the rocker mass to deflect in an x or y direction oriented parallel or perpendicular to the axis. The z spring or the additional spring system allows the rocker mass to deflect in a y or x direction oriented parallel or perpendicular to the axis.