Plasma Lighting Magnetron Frequency Shift and Filament Control

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Solution Overview

Problem

Plasma lighting systems interfere with wireless local area network (WLAN) devices using the same frequency band due to unregulated electron emission and lack of differentiation between initial heating and operation currents, causing communication interference and channel interference.

Innovation Solution

A plasma lighting system with a magnetron having vanes and straps that allow adjustable oscillation frequency, a power source unit for differentiated filament currents, and a control unit to manage these currents, reducing interference by setting the oscillation frequency between 2,480 MHz and 2,490 MHz and lowering the filament current in normal operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the plasma lighting system uses a magnetron with resonance frequency of 2450 MHz, then the lighting function is achieved, but channel interference with WLAN devices occurs

Engineering Contradiction:
Improvelighting functionVSAvoidchannel interference with WLAN
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the oscillation frequency parameter of the magnetron from the conventional 2450 MHz to a new range of 2480-2490 MHz. This frequency shift resolves the channel interference issue with WLAN devices while maintaining the lighting function, as the new frequency band does not overlap with the 2.4 GHz WLAN band.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces adjustable oscillation frequency capability through modified magnetron structure with vanes and straps. This allows the system to dynamically adjust or select from multiple frequency ranges (2480-2490 MHz), providing flexibility to avoid interference with electronic devices while maintaining reliable lighting operation.

Inventive Principle:
Principle #15Dynamics

2Reliability

If high filament current is applied during initial heating to improve starting characteristics, then the plasma lighting system achieves better activation, but interference with WLAN increases

Engineering Contradiction:
Improvestarting characteristicsVSAvoidinterference with WLAN
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic or staged filament current application: a first filament current during initial heating/activation phase, and a second (lower) filament current during normal operation phase. This time-based differentiation reduces WLAN interference during normal operation while maintaining good starting characteristics during the initial phase.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the filament current based on the operational state: high current during startup to ensure reliable plasma ignition, then transitions to low current during normal operation to minimize interference. This dynamic control resolves the contradiction between starting performance and interference reduction.

Inventive Principle:
Principle #15Dynamics

3Illumination intensity

If high filament current is continuously applied to maintain plasma, then the lighting output is sustained, but the lifespan of the magnetron decreases

Engineering Contradiction:
Improvelighting outputVSAvoidlifespan of magnetron
Core Design Contradiction:
Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent uses staged filament current application where high current is applied only during the initial heating phase necessary for plasma activation, then transitions to low or zero filament current during normal plasma operation. This periodic high-current application maintains lighting output while significantly reducing cumulative thermal stress on the magnetron, thereby extending its lifespan.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

Once plasma is established during the initial heating phase, the system maintains continuous lighting output without requiring continuous high filament current. The plasma sustains itself with minimal or no filament current, ensuring continuous useful action (lighting) while reducing harmful continuous high-current exposure to the magnetron.

Inventive Principle:
Principle #20Continuity of useful action

4Adaptability or versatility

If the oscillation frequency is set to 2450 MHz to match conventional standards, then compatibility with existing systems is maintained, but noise and interference increase

Engineering Contradiction:
Improvecompatibility with existing systemsVSAvoidnoise and interference
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the oscillation frequency parameter from the conventional 2450 MHz to 2480-2490 MHz. This parameter change reduces noise and interference by operating in a less congested frequency band, while the modified magnetron structure with adjustable vanes and straps maintains adaptability to various operational requirements.

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 solution effectively reduces interference with WLAN devices, extends the lifespan of the magnetron, and improves system reliability and user convenience by avoiding frequency band changes, while also reducing noise and energy consumption.

Implementation Method 1

a magnetron including a plurality of vanes having accommodating recesses at upper and lower end portions and two pairs of straps accommodated in the accommodating recesses such that they are respectively and alternately brought into contact with the accommodating recesses, the plurality of vanes and the two pairs of straps forming an oscillating circuit

Methodology Applied
Scientific EffectElectron oscillation:

Implementation Method 2

said magnetron providing oscillating microwaves that have an oscillation frequency determined by the plurality of vanes and the straps

Methodology Applied
Scientific EffectElectromagnetic radiation:

Implementation Method 3

a waveguide connected to the magnetron and having a waveguide space to deliver the microwave

Methodology Applied
Scientific EffectMicrowave transmission: Waveguide

Implementation Method 4

a resonator formed to have a mesh form and having a resonance space accommodating the electrodeless bulb and connected to the waveguide

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 5

an electrodeless bulb charged with a luminous material and emitting light according to the microwaves

Methodology Applied
Scientific EffectPlasma excitation: Plasma

Implementation Method 6

the luminous material of the electrodeless bulb is excited. Then, the luminous material charged in the electrodeless bulb is converted into plasma to generate light

Methodology Applied
Scientific EffectLight emission: Luminescence

Data Source

PatentEP2482622B1Plasma lighting system
Publication Date: 2019.03.06 LG ELECTRONICS INC
  • EP2482622B1 patent drawingFigure 1
  • EP2482622B1 patent drawingFigure 2
  • EP2482622B1 patent drawingFigure 3

AI summary

A plasma lighting system is disclosed. Interference with an electronic device using the same band as that of the plasma lighting system can be avoided by changing the shape of vanes constituting a magnetron, and a filament current of the magnetron at an initial starting stage and that in a normal state are adjusted to be different, thus avoiding interference with a wireless LAN and attenuating noise, and a resonator has a mash form to increase efficiency. Because a rectangular waveguide is bent substantially at a right angle, and the magnetron and the resonator are disposed at one side on the basis of a waveguide space of the waveguide, thus reducing the size and an installation space of the plasma lighting system.