Capacitive Sensor With Inclined Electrodes

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Solution Overview

Problem

Conventional capacitive force sensors require complex assembly with electrical wires, which can be damaged during movement and lead to oxidation issues, complicating the assembly process and reducing sensor reliability.

Innovation Solution

A capacitive sensor design featuring inclined electrodes and a movable part that creates a coupling capacitance without an electrical wire, simplifying assembly, preventing wire damage, and eliminating oxidation risks, while allowing for directional movement detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electrical wire is used to connect the measuring circuit to the moving element's electrode, then electrical contact is established, but the assembly becomes complex and the wire is susceptible to damage and oxidation

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the electrical wire from the system entirely. Instead of using a physical wire to connect the measuring circuit to the moving element's electrode, the invention uses a wireless capacitive coupling method where the measuring circuit measures capacitance changes directly through the support structure, eliminating the wire and its associated problems of damage and oxidation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical electrical wire connection with an electrical field-based measurement system. The measuring circuit measures capacitance changes caused by the position of the moving element, substituting the mechanical wire connection with an electromagnetic field-based detection method that is more reliable and less complex.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If an electrical wire is used to connect the measuring circuit to the moving element's electrode, then electrical contact is established, but oxidation of the electrical contacts occurs due to low electrical current

Engineering Contradiction:
Improveelectrical contact stabilityVSAvoidoxidation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the electrical wire from the system entirely. Instead of using a physical wire to connect the measuring circuit to the moving element's electrode, the invention uses a wireless capacitive coupling method where the measuring circuit measures capacitance changes directly through the support structure, eliminating the wire and its associated problems of damage and oxidation.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If the support surfaces are parallel, then the sensor structure is simple, but the sensor cannot detect movement in a preferred direction

Engineering Contradiction:
Improvemovement detection capabilityVSAvoidsupport structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces asymmetry in the support structure by making the second outer surface inclined relative to the first outer surface. This asymmetric configuration creates a preferred direction for movement detection, allowing the sensor to detect movement along the inclination direction while maintaining structural simplicity. The inclined surface geometry provides directional sensitivity without requiring complex additional components.

Inventive Principle:
Principle #4Asymmetry

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 design enhances assembly simplicity, reduces wear on the measurement circuit, prevents oxidation, and effectively detects movement in a preferred direction, improving the reliability and durability of capacitive force sensors.

Implementation Method 1

two electrodes extending opposite each other and movable relative to each other. These two electrodes then form a capacitor defined by a coupling capacitance which is measured using an electrical measuring circuit providing an alternating current. The measured capacitance then depends on the distance between these two electrodes.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

a support comprising a first outer surface on which a first electrode extends and a second outer surface, inclined relative to the first outer surface, on which a second electrode extends; a part, movable relative to the support, the part comprising a first conductive surface and a second conductive surface in electrical contact with the first conductive surface, the first conductive surface extending opposite the first electrode and the second conductive surface extending opposite the second electrode so as to create a coupling capacitance between the first electrode and the second electrode

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP4184138B1Capacitive sensor
Publication Date: 2024.12.04 VALEO COMFORT & DRIVING ASSISTANCE
  • EP4184138B1 patent drawingFigure 1~2

AI summary

The invention relates to a capacitive sensor (1) comprising: - a support (10) comprising a first outer surface (11) on which a first electrode (21) extends and a second outer surface (12), inclined with respect to the first outer surface, on which a second electrode (22) extends; - a part (30), movable with respect to the support, the part comprising a first conductive surface (41) and a second conductive surface (42) in electrical contact with the first conductive surface, the first conductive surface extending opposite the first electrode and the second conductive surface extending opposite the second electrode so as to create a coupling capacitance between the first electrode and the second electrode; - a measuring circuit (60) designed to measure the coupling capacitance.