Portable Tool Safety via Body Capacitance Detection

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Solution Overview

Problem

Existing safety systems for portable electric tools are cumbersome, requiring users to wear metal gloves, special clothing, or ensure electrical conductivity with the ground, and are not suitable for use in humid environments or precise distance measurement.

Innovation Solution

A safety system that uses a radioelectric signal generator to inject a signal into the user's body, which is then emitted as an electromagnetic signal, allowing the portable tool to measure the distance between the user and the tool's machining member and adjust the actuator speed accordingly, without the need for conductive materials or special clothing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal gloves or conductive clothing are used to detect user proximity, then safety detection capability is improved, but device complexity and user burden increase

Engineering Contradiction:

Improvesafety detection capabilityVSAvoidcomplexity of conductive accessories

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/conductive contact-based safety system with an electromagnetic field-based detection system. Instead of requiring metal gloves or conductive clothing to detect user proximity, the system uses a radioelectric signal generator and antenna to create an electromagnetic field that detects the user's presence through capacitive coupling, eliminating the need for complex conductive accessories.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electromagnetic field as an intermediary between the tool and the user. The radioelectric signal generator creates an electromagnetic field that interacts with the user's body capacitance, allowing distance detection without direct conductive contact. This intermediary field enables safety detection while avoiding the complexity of metal gloves or conductive clothing systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If conductive materials and special clothing are required for safety, then detection accuracy is improved, but ease of operation deteriorates

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidease of tool operation

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent makes the user's body the detection element itself. The human body naturally possesses capacitive properties that interact with the electromagnetic field, requiring no special clothing or accessories. The system automatically detects the user's presence and distance by measuring the interaction between the electromagnetic field and the user's body capacitance, making operation as easy as approaching the tool.

Inventive Principle:

Principle #25Self-service

3Reliability

If electrical conductivity with ground is ensured for safety, then safety detection is improved, but adaptability to different environments deteriorates

Engineering Contradiction:

Improvesafety detectionVSAvoidsuitability for different environments

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces ground-based electrical conductivity requirements with electromagnetic field-based capacitive detection. The system measures the user's body capacitance relative to the tool through the electromagnetic field, which does not depend on ground contact or environmental humidity. This allows the safety system to function reliably in diverse environments including humid conditions where ground conductivity may be compromised.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 system provides effective safety without the need for heavy or bulky conductive accessories, operates reliably in various conditions, and allows for precise distance measurement and adjustment of the tool's speed to prevent accidents.

Implementation Method 1

A safety system which uses a radioelectric signal generator to inject a signal into the user's body, which is then emitted as an electromagnetic signal

Methodology Applied

Scientific EffectElectromagnetic radiation:

Implementation Method 2

an antenna to receive the electromagnetic signal and send it to a control unit in the form of a radioelectric signal

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3458228B1System and method for increasing the safety of a portable electrical tool

Publication Date: 2021.11.17 FELCO SA

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AI summary

The present invention relates to a system for increasing the safety of a portable electrical tool (10), comprising: a generator (40) of a radioelectric signal, which generator is electrically coupled to said user (1) so as to inject into the body of the user (1) said radioelectric signal (s(t)), said radioelectric signal (s(t)) then being emitted by said user (1) in the form of an electromagnetic signal; and the portable electrical tool (10), which is arranged to be borne by a member of the user and comprises: a machining member (4); a holding member (2); an actuator connected to the machining member (4); an antenna fastened to the machining member (4) and/or the holding member (2) and arranged to receive a radioelectric signal corresponding to the electromagnetic signal emitted by the user (1). A computing module (30) determines a distance between the user and the machining member and/or holding member on the basis of the electromagnetic signal received by the antenna, and modifies accordingly the speed of the actuator.