Acceleration Sensor Spring Force Compensation Trim Electrodes
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Solution Overview
Problem
Existing acceleration sensors face limitations in reducing spring stiffness while maintaining sensitivity and shock resistance, due to manufacturing constraints.
Innovation Solution
The acceleration sensor employs trimming electrodes connected to the sensor mass and substrate, allowing for adjustable electrostatic forces that counteract spring forces, enabling flexible adjustment of the effective spring constant and reducing manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spring stiffness is reduced to increase sensitivity, then sensitivity to acceleration is improved, but shock resistance deteriorates
Solution Approach 1:
The patent applies electrostatic forces between trim electrodes and the sensor mass to dynamically adjust and compensate the spring force in real-time. By applying a DC voltage to the trim electrodes, an electrostatic force is generated that counteracts the spring force, allowing the effective spring constant to be adjusted without changing the physical spring elements. This resolves the contradiction by enabling low effective stiffness for sensitivity while maintaining the physical spring structure for shock resistance.
Solution Approach 2:
The patent changes the electrical parameter (voltage applied to trim electrodes) to control the electrostatic force, which in turn adjusts the effective spring constant. By varying the voltage, the system can achieve different effective stiffness values without modifying the mechanical spring structure, thus maintaining both sensitivity and shock resistance.
2Measurement precision
If spring stiffness is reduced below manufacturing limits, then sensitivity is improved, but manufacturing feasibility deteriorates
Solution Approach 1:
The patent replaces part of the mechanical spring system with an electrostatic force system. Instead of relying solely on mechanical springs to provide the restoring force, electrostatic forces between the trim electrodes and sensor mass are used to compensate and adjust the spring force. This substitution allows the effective spring constant to be tuned beyond what is achievable with mechanical manufacturing alone.
Solution Approach 2:
The patent uses electrical voltage as a control parameter to adjust the electrostatic force, thereby changing the effective spring constant without changing the physical dimensions or material properties of the manufactured components. This allows sensitivity optimization independent of manufacturing constraints.
3Adaptability or versatility
If additional trim electrodes are added to compensate spring forces, then spring rate adjustability is improved, but device complexity increases
Solution Approach 1:
The patent makes the trim electrodes serve multiple functions: they generate electrostatic forces to compensate spring forces, enable spring constant adjustment, and can potentially serve as detection electrodes. By making the trim electrodes multi-functional, the need for separate adjustment mechanisms is eliminated, reducing overall device complexity while maintaining adjustability.
Solution Approach 2:
The patent combines the function of spring compensation electrodes with the detection electrode function into a single electrode structure. The trim electrodes are integrated with the sensor mass and substrate, merging multiple functions into fewer components, thereby reducing device complexity while maintaining spring rate adjustability.
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 allows for a freely adjustable spring rate, increased sensitivity, and reduced distortions, enhancing the reliability and compactness of the acceleration sensor by compensating spring forces with electrostatic forces, thus overcoming manufacturing limitations.
Implementation Method 1
an electrostatic force is generated on the sensor mass by applying an electrical trim voltage between the first and second trim electrodes, which opposes the spring force
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The invention relates to an acceleration sensor (100) having a sensor material (120) which is mounted by means of spring elements (130) so as to be movable along a movement axis (x) over a substrate (110), first trim electrodes (140) which are connected to the sensor material (120), and second trim electrodes (150) which are connected to the substrate (110) and are associated with the first trim electrodes (140). When the sensor material is deflected along the movement axis, a spring force acting on the sensor material (120) is generated by the spring elements (130), and when the sensor material (120) is deflected, an electrostatic force acting on the sensor material (120), which counteracts the spring force, is generated by application of an electrical trim voltage between the first trim electrodes (140) and the second trim elements (150).