Light-Emitting Device With Opposing Drive Currents for EMI Reduction
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Solution Overview
Problem
Existing light-emitting devices with multiple LEDs in one pixel suffer from electromagnetic interference (EMI) due to aligned magnetic fields and induced electromagnetic waves.
Innovation Solution
A light-emitting device with a first and second light emitter, where the drive currents flow in opposite directions, and their periods of flow at least partially overlap, effectively canceling out the electromagnetic waves generated by each emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitters are arranged in one pixel, then the luminance and color quality are improved, but electromagnetic interference increases due to aligned magnetic fields
Solution Approach 1:
The patent applies asymmetry by arranging light emitters with different orientations so that their current flow directions are not aligned. Specifically, at least one light emitter has a current flow direction that differs from the others, creating asymmetric current paths that generate magnetic fields with different orientations. This asymmetry prevents the constructive interference of magnetic fields that occurs with aligned emitters, thereby reducing electromagnetic interference while maintaining multiple emitters per pixel for improved luminance and color quality.
2Illumination intensity
If drive currents flow through multiple light emitters, then the light output is improved, but electromagnetic waves with aligned phases cause interference
Solution Approach 1:
The patent applies inversion by deliberately orienting at least one light emitter's current flow direction opposite to or differently from the other emitters. This inverted or differentiated orientation causes the magnetic fields generated by these emitters to have opposite or different phases, leading to destructive interference of electromagnetic waves rather than constructive interference. This reduces electromagnetic interference while maintaining the light output from multiple emitters.
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 configuration reduces electromagnetic interference by ensuring that the electromagnetic waves induced by the drive currents in the first and second light emitters have opposite phases, thereby canceling each other out.
Implementation Method 1
A first drive current through the first light emitter and a second drive current through the second light emitter flow in opposite directions. A period in which the first drive current flows and a period in which the second drive current flows at least partially overlap each other.
Data Source
AI summary
A light-emitting device includes a first light emitter and a second light emitter. A first drive current through the first light emitter and a second drive current through the second light emitter flow in opposite directions. A period in which the first drive current flows and a period in which the second drive current flows at least partially overlap each other. This structure causes the phase of an electromagnetic wave induced by the first drive current to be opposite to the phase of an electromagnetic wave induced by the second drive current, thus allowing the electromagnetic waves to at least partially cancel each other and reducing electromagnetic interference.