PC Red LED Phosphor Structure for Color Purity and Blue Pass-Through
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Solution Overview
Problem
Current Phosphor-Converted Red LEDs (PC Red LEDs) face challenges in generating narrowband red light due to the high cost and low absorption efficiency of narrowband red fluoride phosphors, leading to increased manufacturing costs and reduced color purity due to 'blue pass through' and moisture sensitivity.
Innovation Solution
Incorporating a combination of narrowband red fluoride phosphors and broadband red phosphors in a single or double-layer photoluminescence structure, with the broadband phosphor having higher absorption efficiency to reduce blue pass through and improve color purity, while isolating the narrowband phosphor from moisture using innovative packaging structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If narrowband red fluoride phosphors are used to generate narrowband red light, then color purity is improved, but manufacturing cost increases and absorption efficiency decreases
Solution Approach 1:
The patent combines narrowband red fluoride phosphors with broadband red phosphors in a hybrid phosphor system. The broadband phosphors (such as CaAlSiN3:Eu2+) have high absorption efficiency and convert blue light effectively, while the narrowband fluoride phosphors (such as K2SiF6:Mn4+) provide narrowband red emission for high color purity. This merging allows the system to achieve both high absorption efficiency and high color purity while reducing the amount of expensive narrowband phosphor needed.
Solution Approach 2:
The invention uses composite phosphor materials consisting of multiple phosphor types with complementary properties. The broadband red phosphor component provides efficient blue light absorption and high quantum efficiency, while the narrowband fluoride phosphor component contributes narrowband red emission. This composite approach creates a phosphor mixture that achieves high color purity (narrow FWHM) while maintaining high absorption efficiency and reducing manufacturing cost by optimizing the ratio of expensive to inexpensive phosphor materials.
2Manufacturing precision
If narrowband red fluoride phosphors are used, then color purity is improved, but reliability decreases due to moisture sensitivity
Solution Approach 1:
The patent introduces broadband red phosphors as intermediary materials that absorb blue light and re-emit red light, reducing the burden on moisture-sensitive narrowband fluoride phosphors. The broadband phosphors act as a protective intermediary layer that converts blue light before it reaches the narrowband phosphors, thereby reducing their exposure to blue light and minimizing moisture-related degradation. This intermediary approach allows the narrowband phosphors to maintain their high color purity function while the broadband phosphors provide stability and moisture resistance.
3Manufacturing precision
If narrowband red fluoride phosphors are used, then color purity is improved, but absorption efficiency decreases leading to blue pass through
Solution Approach 1:
The patent merges the functions of broadband red phosphors (high absorption efficiency) with narrowband fluoride phosphors (high color purity) in a hybrid phosphor system. The broadband phosphors absorb blue light efficiently and convert it to red light, while the narrowband fluoride phosphors provide narrowband red emission. This merging ensures that most blue light is absorbed by the broadband phosphors before reaching the narrowband phosphors, minimizing blue pass through while maintaining high color purity in the final red light output.
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 approach significantly reduces the usage of narrowband red fluoride phosphor, enhances absorption efficiency, and improves color purity and reliability of PC Red LEDs, achieving high brightness and luminous efficacy comparable to broadband red phosphor-based LEDs.
Implementation Method 1
a photoluminescence material that converts blue light from an LED chip to red light
Implementation Method 2
narrowband red fluoride phosphors...converts substantially all of the excitation light generated by the LED chip to light of a selected color
Data Source
AI summary
An LED package comprising: a housing comprising a two-dimensional array of cups comprising a first cup for a first LED, a second cup for a second LED, a third cup for a third LED, and a fourth cup for a fourth LED; and a lead frame comprising respective anode and cathode regions for each cup. Each anode region comprises an anode electrode on a floor of the cup and an anode terminal for providing power to the anode electrode, and each cathode region comprises a cathode electrode on the floor of the cup and a cathode terminal for providing power to the cathode electrode, and wherein the respective anode and cathode terminals for each cup are located along opposing edges of the housing and are aligned with each other.