Capacitive Load Sensor with Curved Elastic Body
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Solution Overview
Problem
Capacitive load sensors have a limited dynamic range where capacitance changes linearly with load, making it difficult to detect loads through simple processing in a wide range due to the narrow range of linear capacitance change.
Innovation Solution
A load sensor design featuring an electrode, a dielectric, and an elastic body with conductivity, where the elastic body is bent in the up-down direction and has projecting portions on its surface, allowing the number of contacting portions and contact area with the dielectric to increase with load, thereby changing capacitance linearly across a wide range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional capacitive load sensor uses a flat elastic conductive layer, then the structure is simple, but the range where capacitance changes linearly according to the load is narrow
Solution Approach 1:
The elastic body is designed with a bending shape (curved surface) instead of a flat structure. This curvature causes the projecting portions to sequentially contact the dielectric surface as load increases, creating a progressive capacitance change that maintains linearity across a wider dynamic range.
Solution Approach 2:
The elastic body surface is divided into multiple projecting portions instead of a continuous flat surface. These discrete segments contact the dielectric sequentially under increasing load, enabling the capacitance to change linearly through controlled engagement of individual segments rather than uniform compression.
2Ease of manufacture
If the elastic body is made flat, then manufacturing is easier, but the capacitance changes non-linearly with load beyond a small range
Solution Approach 1:
The elastic body incorporates a bending shape with curved surfaces instead of being completely flat. This curvature is designed to control the sequential contact of projecting portions with the dielectric, ensuring linear capacitance change across an extended load range while remaining manufacturable through standard molding techniques.
3Area of stationary object
If a rough surface with many uneven structures is used, then contact area increases, but the linear capacitance change range remains limited
Solution Approach 1:
Instead of using a continuous rough surface, the elastic body features discrete projecting portions arranged in a segmented pattern. These segments contact the dielectric sequentially as load increases, providing sufficient total contact area while maintaining linear capacitance progression through controlled engagement of individual segments.
Solution Approach 2:
The projecting portions are arranged on a curved surface that facilitates sequential contact with the dielectric. This curvature ensures that as load increases, different segments engage in a controlled manner, expanding the dynamic range where capacitance changes linearly while maintaining adequate contact area.
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
Enables load detection through simple processing in a wide dynamic range by linearly changing capacitance in response to varying loads, expanding the range where capacitance changes linearly.
Implementation Method 1
an elastic body disposed so as to face a lower surface of the dielectric and having conductivity plurality of projecting portions are formed on an upper surface of the elastic body, and the elastic body has a bending shape that is bent in an up-down direction
Implementation Method 2
the capacitance of a capacitor formed by the electrode, the dielectric, and the conductive elastic body can be changed linearly in a wide load range
Data Source
AI summary
A load sensor includes: an electrode; a dielectric formed on a lower surface of the electrode; and a conductive elastic body disposed so as to face a lower surface of the dielectric and having conductivity. A plurality of projecting portions are formed on an upper surface of the conductive elastic body. The conductive elastic body has a bending shape that is bent in an up-down direction, in at least a part thereof. Alternatively, at least either the conductive elastic body or the electrode has a bending shape that is bent in an up-down direction, in at least a part thereof.