Thermochromic Coating on Lighter Shield for Heat Warning

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Solution Overview

Problem

Handheld lighters with metallic shields often reach temperatures that can burn users due to the heat source, and existing solutions do not provide a simple and cost-effective means to warn users of this hazard.

Innovation Solution

A thermochromic coating is applied to the metallic shield, comprising an electron-donative organic compound, an electron-accepting compound, and a reaction medium that enables a reversible electron transfer reaction, changing color in response to temperature changes above 60°C, providing a visible warning when the shield is too hot to touch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a metallic shield is used to steady the gas flame, then the flame stability is improved, but the shield temperature increases to burnable levels

Engineering Contradiction:
Improveflame stabilityVSAvoidshield temperature
Core Design Contradiction:
Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent applies a thermochromic coating to the metallic shield that changes color when the shield temperature exceeds a safe threshold. This visual color change serves as a warning indicator to users, allowing the shield to maintain its flame-stabilizing function while providing safety awareness through color transformation.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The thermochromic coating acts as an intermediary between the hot metallic shield and the user. It translates the thermal energy into a visual signal without direct contact, mediating the safety communication without interfering with the shield's primary function of stabilizing the gas flame.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a temperature warning system is added to the lighter, then user safety is improved, but the device complexity increases

Engineering Contradiction:
Improveuser safetyVSAvoidlighter complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a thermochromic coating that undergoes reversible color changes in response to temperature variations. This passive optical system provides temperature warning functionality without requiring active electronic components, motors, or power sources, thereby maintaining device simplicity while enhancing safety.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The thermochromic coating is a self-regulating system that automatically responds to temperature changes without external control. The coating self-activates the warning function when temperature thresholds are exceeded and self-resets when cooling occurs, eliminating the need for external power sources or control mechanisms.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If a thermochromic coating with narrow hysteresis is used, then the temperature warning accuracy is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvetemperature warning accuracyVSAvoidcoating application precision
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent formulates the thermochromic coating with specific ratios of electron-donative organic compound, electron-accepting compound, and reaction medium to achieve the desired hysteresis characteristics. By adjusting these compositional parameters, the coating exhibits narrow temperature hysteresis for accurate warning while remaining manufacturable with standard coating application processes.

Inventive Principle:
Principle #35Parameter changes

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 thermochromic coating effectively warns users of excessive heat by changing color, ensuring safety without additional complexity or cost, maintaining reliability through its reversible and non-melt memory properties.

Implementation Method 1

The thermochromic coating is configured to reversibly change color in response to an increase of the temperature of the metallic shield to a first temperature of about 60 °C or above. The thermochromic coating is configured to reversibly change color in response to a decrease of the temperature of the metallic shield to a second temperature which is about 0 to about 20 °C below the first temperature.

Methodology Applied
Scientific EffectThermochromism: Thermochromism

Implementation Method 2

The thermochromic coating comprises an electron-donative organic compound (component (a)), an electron-accepting compound (component (b)), and a reaction medium which enables an electron transfer reaction between the components (a) and (b) above the melting or softening point of the reaction medium (component (c)).

Methodology Applied
Scientific EffectElectron transfer reaction: Redox Reactions

Implementation Method 3

a reaction medium which enables an electron transfer reaction between the components (a) and (b) above the melting or softening point of the reaction medium (component (c))

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3859211B1Handheld lighter with high temperature warning indicator
Publication Date: 2024.01.24 SOCIETE BIC SA
  • EP3859211B1 patent drawingFigure 1~2

AI summary

The present disclosure relates to a temperature warning indicator for a handheld lighter which warns the user that parts of the lighter may be too hot to touch without burning the user.