Removable Knob Switch Resonance Sensing for Precise IH Power Control

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Solution Overview

Problem

Induction heating devices using capacitive touch-type knob switches face increased manufacturing costs and decreased efficiency due to the need for multiple touch sensors to sense rotation, leading to potential operational errors and inaccurate thermal power adjustments.

Innovation Solution

An induction heating device that adjusts thermal power using a frequency pulse based on the resonance characteristic between a knob switch and a resonance detecting unit, which varies with the rotation degree of the knob switch, incorporating a first and second magnetic material and capacitors to output a frequency pulse corresponding to an impedance inflection point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive touch-type knob switches with multiple touch sensors are used to sense rotation, then the induction heating device can detect rotation degree, but manufacturing costs increase and manufacturing efficiency decreases

Engineering Contradiction:
Improverotation degree detectionVSAvoidmanufacturing cost and efficiency
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the capacitive touch sensor system with a magnetic field-based detection system. A magnet is attached to the knob, and a magnetic sensor detects the magnet's position to determine rotation degree. This substitution eliminates the need for multiple touch sensors and their complex control logic, thereby reducing manufacturing costs and improving manufacturing efficiency while maintaining accurate rotation detection capability.

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

Solution Approach 2:

The patent changes the detection parameter from capacitive touch signals to magnetic field signals. By using a magnet and magnetic sensor, the system detects rotation through changes in magnetic field position rather than through multiple touch sensor readings. This parameter change simplifies the detection mechanism and reduces manufacturing complexity.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple touch sensors are used to sense knob rotation, then rotation degree can be detected, but the device complexity increases

Engineering Contradiction:
Improverotation degree detectionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex multi-sensor capacitive touch system with a simple magnet and magnetic sensor arrangement. The magnet attached to the knob creates a magnetic field that the magnetic sensor detects, providing rotation information through a single sensor instead of multiple touch sensors. This significantly reduces device complexity.

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

Solution Approach 2:

The magnetic sensor serves multiple functions: detecting the magnet's presence, determining rotation degree, and identifying knob position. This multi-functionality eliminates the need for separate touch sensors and control logic for each detection task, thereby reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If multiple touch sensors are used for rotation sensing, then thermal power adjustment can be controlled, but operational errors and inaccurate adjustments may occur

Engineering Contradiction:
Improvethermal power controlVSAvoidoperational accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces the capacitive touch sensor system with a magnetic field-based detection system. A magnet is attached to the knob, and a magnetic sensor detects the magnet's position to determine rotation degree. This substitution eliminates the need for multiple touch sensors and their complex control logic, thereby reducing manufacturing costs and improving manufacturing efficiency while maintaining accurate rotation detection capability.

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

4Adaptability or versatility

If a detachable knob switch is provided on the induction device, then the device can be adjusted for different cooking areas, but the knob switch may become detached or lost

Engineering Contradiction:
Improveknob switch compatibilityVSAvoidknob switch attachment
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the mechanical attachment system with a magnetic attachment system. A magnet is embedded in the knob switch, and it magnetically attaches to a corresponding magnetic material in the device body. This magnetic attachment provides secure fixation while allowing easy attachment and detachment, maintaining versatility while improving reliability and preventing loss.

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

This solution reduces manufacturing costs, simplifies the manufacturing process, and enhances the accuracy of thermal power adjustments by using a frequency pulse to control the heating coil, ensuring precise power control.

Implementation Method 1

a resonance detecting unit configured to output a frequency pulse based on a resonance characteristic between the resonance detecting unit and the knob switch

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

the first magnetic material 16 has a polarity opposite to a polarity of a second magnetic material disposed in the lower portion of the knob area, and the first magnetic material 16 can be attached to the knob area using an attractive force between the first magnetic material 16 and the second magnetic material

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 3

The induction device denotes a cooking device that performs heating using an induction heating method

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP3823418B1Removable knob switch device and induction heating cooker using knob switch
Publication Date: 2023.08.16 LG ELECTRONICS INC
  • EP3823418B1 patent drawingFigure 1
  • EP3823418B1 patent drawingFigure 2
  • EP3823418B1 patent drawingFigure 3

AI summary

The present disclosure relates to an induction heating device comprising: a heating coil provided in a main body; a knob switch, detachable from and attachable to a knob area formed on one surface of the main body, for adjusting a heating power of the heating coil by rotation when attached to the knob area; a resonance detecting unit for outputting a frequency pulse corresponding to an impedance inflection point that varies according to a degree of rotation of the knob switch; and a controller for controlling the heating power of the heating coil according to the frequency pulse.