Fluorescent Thermochromic Hob Indicator for Clear Residual Heat Display

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Solution Overview

Problem

Existing optical temperature displays for cooking devices, particularly hot and residual heat indicators, face limitations in visibility and complexity, especially when integrated into conventional hob plates, and do not effectively utilize quantum properties of thermochromic materials for enhanced visibility.

Innovation Solution

The use of fluorescent thermochromic materials with particle sizes between 10 nm and 80 nm, predominantly between 20 nm and 50 nm, which exhibit quantum effects, are applied under or adjacent to the hob plate, allowing for increased visibility through fluorescence, especially at high temperatures, and can be integrated into various cooking device configurations, including induction heating and radiant heaters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional thermochromic material is used for temperature display, then the display can indicate temperature changes, but the visibility is insufficient especially through conventional hob plates

Engineering Contradiction:
Improvevisibility of temperature displayVSAvoidreliability of temperature indication
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies fluorescence excitation parameters (wavelength, intensity) to the thermochromic material to enhance its visibility. By changing the optical parameters and using fluorescence excitation, the temperature display becomes significantly more visible through conventional hob plates while maintaining reliable temperature indication.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary fluorescence excitation source (such as UV-LEDs or phosphors) that mediates between the thermochromic material and the observer. This intermediary enhances the visibility of the temperature display by converting invisible or faint thermochromic changes into bright fluorescent signals that can be seen through the hob plate.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If thermochromic material is applied under the hob plate, then the display structure is simplified, but the visibility and recognition through the hob plate is reduced

Engineering Contradiction:
Improvestructure of optical display deviceVSAvoidvisibility through hob plate
Core Design Contradiction:
Device complexityVSIllumination intensity

Solution Approach 1:

The patent changes the optical parameters of the thermochromic material by applying fluorescence excitation. This allows the material to emit bright fluorescent light that can penetrate through conventional hob plates, thereby maintaining the simplified under-plate structure while significantly improving visibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs periodic or pulsed fluorescence excitation (e.g., through LED activation) to enhance the visibility of the thermochromic display through the hob plate. This periodic excitation creates intense, periodic fluorescent emission that improves recognition while maintaining structural simplicity.

Inventive Principle:
Principle #19Periodic action

3Illumination intensity

If quantum dot materials with small particle size are used, then fluorescence and quantum effects are enhanced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvefluorescence visibilityVSAvoidparticle size control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent optimizes the particle size parameter of the quantum dot thermochromic material to a specific range (10-80 nm) where quantum effects and fluorescence are maximized. By carefully controlling this size parameter, the patent achieves enhanced fluorescence visibility while managing manufacturing precision requirements through defined specifications.

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

This solution provides a highly visible and reliable optical temperature display that mimics an illuminated warning, enhancing safety by clearly indicating hazardous temperatures through a color change, even through conventional hob plates, with improved ease of use and comfort.

Implementation Method 1

The indicator comprises thermochromic material for temperature indication. The thermochromic material essentially consists of metal oxides which are fluorescent and are present as a powder. A predominant proportion of the powder or the thermochromic material has a particle size between 10 nm and 80 nm

Methodology Applied
Scientific EffectThermochromism: Thermochromism

Implementation Method 2

the material is fluorescent and is selected in particular in such a way that it lights up more or less by itself above the transition temperature

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentEP2587165B1Cooking appliance with optical temperature indication
Publication Date: 2014.12.10 E G O ELEKTRO GERAETEBAU GMBH
  • EP2587165B1 patent drawingFigure 1~4
  • EP2587165B1 patent drawingFigure 5~6

AI summary

A cooking device with a hob plate and a heating device underneath has a display device for optically displaying the temperature underneath the hob plate. The display device has thermochromic material for temperature display, the thermochromic material consisting essentially of metal oxides that are fluorescent and are present as a powder in the manner of quantum dots with a very predominant proportion of grain sizes between 10 nm and 80 nm and a color are added.