Handheld Cutting Tool Safety Circuit Impedance Detection

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Solution Overview

Problem

Hand-held cutting tools, such as scissors and shears, used in farming and vineyard pruning often cause accidents and damage to installation components like trellis wires due to unintended contact, with existing safety systems being either ineffective or cumbersome.

Innovation Solution

An electronic safety circuit integrated into the tool that detects changes in impedance between the user's body and the cutting blades, using conductive accessories like socks and footwear, to prevent accidents by immediately stopping the cutting motion when unintended contact is detected, while allowing normal operation when cutting intended materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If passive protective items like metallic mail gloves are used to prevent accidents, then safety is improved, but the gloves become extremely heavy and uncomfortable

Engineering Contradiction:
ImprovesafetyVSAvoidglove weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical protective system (metallic mail gloves) with an electronic control system that uses electrical conductivity detection to identify unintended contact and automatically stops the cutting tool, thereby maintaining safety without the weight and discomfort of protective gloves

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

2Reliability

If active electronic control systems based on metallic mail gloves are used, then safety is improved, but system complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the conductivity sensing function from the gloves themselves and integrates it directly into the tool's control system, eliminating the need for separate conductive gloves and reducing overall system complexity while maintaining safety functionality

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the safety detection function with the tool's existing control circuitry by integrating conductivity sensors and control logic into the tool housing, thereby reducing system complexity compared to separate glove-based systems

Inventive Principle:
Principle #5Merging (Combining)

3Object-affected harmful factors

If remote detection via electromagnetic waves is used, then safety coverage is improved, but precision and reliability decrease

Engineering Contradiction:
Improvesafety coverageVSAvoiddetection precision
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent uses electrical conductivity as an intermediary property to detect unintended contact, leveraging the fact that human skin and most natural materials have different conductivity characteristics than metal wires, thereby achieving both precision and comprehensive safety coverage

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If electronic safety systems with transmitting and receiving means are incorporated into gloves, then safety functionality is improved, but usage becomes awkward and system complexity increases

Engineering Contradiction:
Improvesafety functionalityVSAvoidusage comfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent enables the tool to perform its own safety monitoring function by integrating conductivity sensors and control logic directly into the tool, eliminating the need for the user to wear or operate separate safety devices, thereby improving ease of operation while maintaining safety functionality

Inventive Principle:
Principle #25Self-service

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 effectively prevents accidents and damage to installation components by rapidly differentiating between intended and unintended contact, ensuring the safety and integrity of the cutting process with minimal user discomfort and system complexity.

Implementation Method 1

An electronic safety circuit integrated into the tool that detects changes in impedance between the user's body and the cutting blades

Methodology Applied
Scientific EffectElectrical impedance: Electrical Resistance

Data Source

PatentEP2825811B1Electric cutting tool with safety stop
Publication Date: 2016.02.24 FLASH ELETTRONICA DI DUCCIO GEMIGNANI
  • EP2825811B1 patent drawingFigure 1
  • EP2825811B1 patent drawingFigure 2

AI summary

The present invention relates to a cutting kit comprising a hand-held cutting tool that includes: a box body (2) made of an electrically non- conductive material; a handgrip (2a) for a hand of a user provided on said body (2); cutting means (1) made of an electrically conductive material extending from said body (2); an electric driving circuit arranged within said body (2) for the operation of said cutting means (1); command and control means (3) of said driving circuit arranged on said handgrip (2a); and a safety circuit (4) adapted to intervene on said driving circuit to control said cutting means (1) independently of the control of said command and control means (3). Said threshold value is a value corresponding to a value detected when said cutting means (1) accidentally make contact with, and are in the stage of incipient injury to, the hand of the user not holding the tool. The cutting kit is characterized in that it also comprises footwear means that can be worn by the user to ensure electrical conductivity between at least one of the user's feet and the ground, said footwear means being adapted to create an impedance on the circuit bridge formed between the handgrip hand and ground at least less than half the impedance that is created on a circuit closing bridge external to the tool, through the user's body, between said cutting means (1) and said electrically conductive element (5), in said stage of incipient injury corresponding to said threshold value.