Capacitive Force Sensor with Tilting Displacement Body
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Solution Overview
Problem
Conventional capacitive force sensors are affected by temperature changes and in-phase noise, leading to fluctuations in output and increased production costs when attempting to mitigate these issues.
Innovation Solution
A force sensor design featuring a deformable body with a tilting portion and displacement bodies connected to capacitive elements, amplifying displacement for sensitive detection, and using multiple capacitive elements to differentiate force directions, thereby reducing noise and temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional capacitive force sensors are used, then the sensor structure is simple and production cost is low, but the output fluctuates due to temperature changes and in-phase noise
Solution Approach 1:
The sensor is divided into multiple capacitive elements (first and second capacitive elements) arranged in specific orientations. Each element detects force components in different directions, and the final force magnitude is calculated by combining these components. This segmentation allows the sensor to maintain simple individual element structures while achieving stable, noise-resistant force measurement through differential calculation.
2Measurement precision
If strain-gauge force sensors are used, then force and torque detection is achieved, but the assembling process is complicated and stopper mechanism cannot be contained
Solution Approach 1:
The invention replaces the strain-gauge mechanical attachment system with an integrated capacitive sensing system. The capacitive elements are formed as integral parts of the sensor structure rather than being attached separately, eliminating complex assembly steps. The stopper mechanism is also integrated into the capacitive structure, allowing it to be contained within the sensor body without complicating the assembly process.
3Reliability
If detection circuit is changed to solve temperature and noise issues, then output stability is improved, but production cost increases
Solution Approach 1:
The invention converts the potential harm of temperature changes and noise into a benefit by using differential measurement. The first and second capacitive elements are positioned to experience similar environmental conditions, so temperature-induced changes affect both elements equally. By calculating the difference between their outputs, common-mode noise and temperature effects are rejected, achieving stable measurements without expensive temperature compensation circuits.
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
The design results in a cost-effective, highly sensitive force sensor that minimizes the impact of temperature changes and in-phase noise, providing stable and accurate force measurements.
Implementation Method 1
the detection circuit includes a capacitive element disposed at the displacement portion, and detects an applied force in accordance with a change in the capacitance value of the capacitive element
Implementation Method 2
a deformable body that includes a force receiving portion and a fixed portion, and is elastically deformed by a force acting on the force receiving portion
Data Source
AI summary
A capacitive force sensor that is inexpensive but highly sensitive, and is hardly affected by temperature changes and in-phase noise in the use environment. A force sensor includes: a deformable body having a force receiving portion and a fixed portion; a displacement body that is connected to the deformable body, and is displaced by elastic deformation caused in the deformable body; and a detection circuit that detects an applied force, in accordance with the displacement caused in the displacement body.