Capacitance-Based Load Sensor With Dielectric Stress Relaxation
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Solution Overview
Problem
Existing load sensors are prone to dielectric body breakage due to stress, leading to inappropriate load detection when a short circuit occurs between conductive members.
Innovation Solution
A load sensor design featuring a dielectric body with a stress relaxation part, such as a clearance, to release stress and prevent breakage, ensuring accurate load detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dielectric body is used in the load sensor, then accurate load detection is achieved, but the dielectric body may break due to stress during load application
Solution Approach 1:
The dielectric body is segmented into multiple regions with different properties: a stress concentration region that absorbs stress during load application and a non-stress concentration region that maintains dielectric function. This segmentation allows the dielectric body to withstand stress without breaking while preserving measurement accuracy.
Solution Approach 2:
Different regions of the dielectric body are given different local qualities: the stress concentration region has properties that allow stress absorption (such as lower density or different material composition), while the non-stress concentration region maintains high dielectric strength. This local differentiation resolves the contradiction between stress resistance and measurement accuracy.
2Strength
If the dielectric body is made thicker to prevent breakage, then durability improves, but the sensor size increases
Solution Approach 1:
Instead of uniformly thickening the dielectric body, the invention segments it into regions with different thicknesses: the stress concentration region has greater thickness for durability, while the non-stress concentration region maintains minimal thickness for compact size. This selective thickening prevents breakage without significantly increasing overall sensor volume.
Solution Approach 2:
The dielectric body exhibits local quality variations in thickness: thicker in stress-prone areas for durability, thinner in non-stress areas for compactness. This local differentiation allows the sensor to achieve both durability and small size simultaneously.
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 stress relaxation part inhibits dielectric body breakage, allowing for reliable and precise load detection even under repeated stress applications.
Implementation Method 1
The dielectric body has a stress relaxation part for releasing stress applied to the dielectric body during load application
Implementation Method 2
the detector detects a pressing force, based on change in capacitance between the first electrically-conductive member and the second electrically-conductive member
Data Source
AI summary
A load sensor includes: a first base member and a second base member disposed so as to face each other; an electrically-conductive elastic body disposed on an opposing face of the first base member; a wire member that is electrically conductive and disposed between the second base member and the electrically-conductive elastic body; and a dielectric body disposed between the electrically-conductive elastic body and the wire member. The dielectric body has a stress relaxation part for releasing stress applied to the dielectric body during load application.