Capacitive Acceleration Sensor Rotational Electrode Design
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Solution Overview
Problem
Capacitive acceleration sensors face limitations in sensitivity and performance, particularly in small designs, due to the inherent limitations of capacitive measuring principles and electrode configurations, which affect their ability to accurately measure acceleration across various ranges.
Innovation Solution
The design enhances capacitance sensitivity by shaping the electrodes to maximize the area away from the axis of rotation and using torsion springs for support, allowing for rotational motion that increases capacitance change, and potentially incorporating a second stationary electrode to optimize capacitance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor is designed with small dimensions, then the device size is reduced, but the capacitance sensitivity decreases
Solution Approach 1:
The patent applies local quality by creating non-uniform electrode spacing where the gap between movable and stationary electrodes varies across the electrode surface. This results in localized regions of high capacitance change density, concentrating the sensitivity in specific areas rather than distributing it uniformly, thereby maintaining high sensitivity in compact sensor designs
Solution Approach 2:
The patent transitions from one-dimensional translatory motion to two-dimensional rotational motion of the movable electrode. This dimensional change allows the electrode to sweep across a larger area relative to the stationary electrode, increasing the effective capacitance change area and sensitivity without proportionally increasing the sensor footprint
2Device complexity
If translatory motion is used, then the structure is simple, but the capacitance sensitivity is insufficient
Solution Approach 1:
The patent employs dynamic rotational motion of the movable electrode instead of static or simple translatory positioning. The rotational movement creates time-varying capacitance changes as different portions of the movable electrode pass by the stationary electrode, significantly enhancing the dynamic range and sensitivity of the acceleration measurement
Solution Approach 2:
The patent uses asymmetric electrode configurations where the movable and stationary electrodes have different geometries and are positioned at specific orientations. This asymmetry, combined with rotational motion, creates uneven capacitance distribution that maximizes the capacitance change signal for a given acceleration input
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 approach improves the sensitivity and performance of capacitive acceleration sensors by enhancing capacitance change during rotational motion, enabling more accurate and reliable acceleration measurement, particularly in small sensor designs.
Implementation Method 1
the movable electrode of the acceleration sensor is rigidly supported at the axis of rotation, such that the movable electrode is free to turn in a rotational motion about the axis of rotation
Implementation Method 2
The capacitance between the surfaces, i.e. the capacity for storing electric charge, depends on the area of the surfaces and on the distance between the surfaces
Data Source
AI summary
The invention relates to measuring devices used in the measuring of acceleration and, more specifically, to capacitive acceleration sensors. The capacitive acceleration sensor according to the present invention contains a movable electrode (5) supported at an axis of rotation (7). The capacitance change in the pair of electrodes of the acceleration sensor, according to the present invention, is enhanced. The acceleration sensor structure, according to the present invention, enables improving the capacitance sensitivity of the pair of electrodes based on rotational motion and measuring acceleration with good performance in capacitive acceleration sensor designs.