Capacitive Acceleration Sensor with Single-Base Suspension
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Solution Overview
Problem
Existing acceleration sensors with a mass movably supported outside its center of gravity suffer from low detection accuracy for accelerations not perpendicular to the base surface due to minimal distance change during tilting, and they cannot be installed in compact housings without limiting the mass's movability, making them unsuitable for small, portable devices.
Innovation Solution
The acceleration sensor features a mass exposed from a material layer, with electrodes and spring elements situated between the mass and the support substrate, allowing for high detection accuracy in multiple spatial directions by using a single base surface suspension and subdivided electrodes for differential capacitance measurement, and adjustable spring constants achieved through cavities sealed by diaphragms, enabling precise measurement of small accelerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mass is supported on only one base surface to increase deflection amplitude, then detection accuracy is improved, but the mass becomes less stable
Solution Approach 1:
The patent applies local quality by providing suspension elements only at specific locations (edges or corners) of the mass rather than uniform support across the entire base surface. This localized suspension approach allows the mass to deflect freely in the measurement direction while maintaining stability through strategically positioned support points, resolving the contradiction between detection accuracy and stability.
2Volume of moving object
If the gap between base plate and mass is filled with housing material for compact installation, then device size is reduced, but mass movability is limited
Solution Approach 1:
The patent segments the housing into distinct regions: a first region containing the base plate and mass, and a second region filled with housing material. This segmentation allows the mass to move freely within its functional space while the housing material provides compact enclosure, resolving the contradiction between device size reduction and mass movability.
Solution Approach 2:
The patent introduces an intermediary air gap or vacuum space between the mass and the housing material filling. This intermediary region acts as a mediator that allows the mass to deflect and move for acceleration detection while still enabling compact housing design, resolving the contradiction between compact installation and mass movability.
3Measurement precision
If electrodes are subdivided for differential capacitance measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the electrodes into multiple independent electrode pairs arranged around the mass. Each pair can be independently connected to measurement electronics, enabling differential capacitance measurement that improves precision while maintaining manageable device complexity through modular electrode configuration.
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 enhances detection accuracy across all spatial directions, allows for miniaturization, and enables installation in compact housings by increasing the deflection amplitude and capacitance change, thereby improving measurement precision and adaptability.
Implementation Method 1
at least one spring element which generates a restoring force when the mass is deflected from its neutral position
Implementation Method 2
first electrodes on the mass and second electrodes being located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time
Data Source
AI summary
An acceleration sensor having a mass which is movably supported outside its center of gravity, first electrodes on the mass and second electrodes located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time. At least one spring element which generates a restoring force when the mass is deflected from its neutral position is provided on the side of the mass facing the capacitive sensor. The mass may be obtained by being exposed from a material layer, and the mass is surrounded, at least at its side faces, by this material.