Multi-Wavelength LED Structure Without Phosphor White Conversion
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Solution Overview
Problem
Existing white light emitting devices using phosphors are complex to manufacture, costly, and prone to heat degradation due to non-heat-resistant resins containing phosphors.
Innovation Solution
A light emitting device comprising a short wavelength light emitting portion and a long wavelength light emitting portion, combined by a coupling layer, which emits multi-wavelength light without the use of phosphors, allowing for white light emission at wafer or chip levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor and resin are used to convert blue light to white light, then white light emission is achieved, but manufacturing complexity and production cost increase
Solution Approach 1:
The patent extracts and eliminates the phosphor and resin components from the white light emitting device. Instead of using blue LED chips with phosphor converters, the invention uses multiple LED chips with different wavelengths (violet, blue, cyan) directly to generate white light, thereby removing the problematic phosphor-resin system and simplifying the device structure
Solution Approach 2:
The patent segments the white light generation function into multiple independent LED chips emitting at different wavelengths (violet 405nm, blue 450nm, cyan 495nm). Each LED chip operates independently without requiring phosphor conversion, and their combined output produces white light, thus eliminating the need for phosphor materials and reducing manufacturing complexity
2Illumination intensity
If phosphor-containing resin is used for wavelength conversion, then white light is emitted, but heat resistance and durability deteriorate over time
Solution Approach 1:
The patent removes the heat-sensitive phosphor-containing resin from the device structure. By using direct-emission LED chips at multiple wavelengths, the invention eliminates the resin material that degrades under thermal stress, thereby significantly improving the device's heat resistance and long-term reliability
Solution Approach 2:
The patent uses multiple LED chips with different wavelength characteristics to replicate the function previously performed by phosphor materials. The violet, blue, and cyan LED chips collectively produce the spectral output that would have required phosphor conversion, but without the thermal degradation issues of phosphor-resin systems
3Illumination intensity
If multiple LED stacks with different wavelengths are combined, then multi-wavelength light emission is achieved, but device structure becomes more complex
Solution Approach 1:
The patent merges multiple LED stacks with different wavelength emissions (violet, blue, cyan) into a single integrated device structure. The LED stacks are arranged in parallel and electrically connected to common electrodes, combining their light output to produce white light while maintaining a compact and unified device architecture
Solution Approach 2:
The patent designs a universal device structure that can accommodate multiple LED stacks with different wavelength characteristics. The common electrode design and parallel arrangement allow the device to perform multiple functions (emitting violet, blue, cyan, and combined white light) through a single integrated structure, reducing overall device complexity
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 simplifies manufacturing, reduces production costs, and enhances durability by eliminating heat-sensitive phosphors, while achieving efficient multi-wavelength light emission.
Implementation Method 1
Each of the first and second LED stacks includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer
Data Source
AI summary
A light emitting device includes a short wavelength light emitting portion, a long wavelength light emitting portion, and a coupling layer combining the short wavelength emitting portion and the long wavelength light emitting portion. Each of the short wavelength light emitting portion and the long wavelength light emitting portion includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer. The active layer of the long wavelength light emitting portion contains more Indium (In) than the active layer of the short wavelength light emitting portion, and the short wavelength light emitting portion emits light of a shorter wavelength than that of light emitted from the long wavelength light emitting portion.