Cooktop Touch Key Layout for False-Touch Heating Control

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Solution Overview

Problem

Conventional cooking devices with touch keys on top plates are prone to unintended operation changes when users accidentally touch the keys with cloths or spills, leading to fluctuations in electricity conduction to the heating source, affecting safety and convenience.

Innovation Solution

A cooking device with a cancel electrode on the lower surface of the top plate near the touch key, which detects impedance changes to prevent unintended operation by maintaining electricity conduction and limiting control commands when the touch key is touched accidentally, ensuring stable heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a touch key is provided on the top plate for user operation, then ease of operation is improved, but reliability deteriorates due to unintended operation when users accidentally touch the key with cloths or spills

Engineering Contradiction:
Improvetouch key operationVSAvoidfalse operation prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The electrode structure is segmented into multiple regions: a touch key electrode for intentional operation and a cancel electrode for detecting accidental contact. This segmentation allows the system to distinguish between intended and unintended user actions by monitoring which electrode is contacted

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cancel electrode acts as an intermediary detection element that monitors the operational environment. When accidentally contacted, it serves as a mediator to prevent the control unit from executing commands from the touch key, thereby blocking false operations without affecting intentional user input

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the touch key detection sensitivity is increased to detect finger touches, then ease of operation is improved, but object-affected harmful factors worsen due to detection of accidental touches with cloths or spills

Engineering Contradiction:
Improvetouch detection sensitivityVSAvoidaccidental touch detection
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The detection system is divided into separate functional zones: the touch key electrode with high detection sensitivity for finger contact, and the cancel electrode that specifically monitors for accidental contact objects. This spatial segmentation allows each electrode to be optimized for its specific detection purpose

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The touch key and cancel electrode are positioned asymmetrically relative to the top plate surface and each other. The touch key is positioned for optimal finger contact, while the cancel electrode is positioned to detect accidental contact from the sides or above, creating asymmetric detection zones that reduce false positives

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

Prevents false operations and maintains consistent heating by accurately differentiating intended and unintended touch inputs, enhancing user safety and convenience by preventing unintended changes in electricity conduction to the heating source.

Implementation Method 1

detecting that an impedance between the cancel electrode and a ground potential is lowered by greater than or equal to a predetermined value compared to when the portion of the top plate near the cancel electrode is not touched with a finger

Methodology Applied
Scientific EffectImpedance detection: Electrical Resistance

Data Source

PatentEP2107856B1Cooking device
Publication Date: 2014.11.05 PANASONIC HOLDINGS CORP
  • EP2107856B1 patent drawingFigure 1~3
  • EP2107856B1 patent drawingFigure 4~5
  • EP2107856B1 patent drawingFigure 6

AI summary

There is provided a cooking device that prevents an electricity conduction setting to a heating source from fluctuating when a user is not intending to operate a touch key. The cooking device includes a heating source (10) for heating an object to be heated; a top plate (1) provided on an upper surface of the device; a touch key (13) that is provided on the top plate and is operable to input a control command by being touched with a finger; a cancel electrode (5) provided at a periphery of the touch key; and a control unit (8) for controlling an electricity conduction to the heating source based on the control command. When detecting that a portion of the top plate near the cancel electrode is touched with the finger, the control unit (8) maintains a condition of electricity conduction to the heating source in time of the detection, and limits an operation based on the control command input to the touch key while detecting that the portion of the top plate near the cancel electrode is being touched with the finger.