White LED Diffusing Layer for Uniform Color and Lower Phosphor Use
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Solution Overview
Problem
Existing color tunable white light emitting devices, such as CSP and COB LEDs, face challenges with high manufacturing costs and low color uniformity due to the need for individual coating of LED chips and the use of excessive photoluminescence material.
Innovation Solution
A white light emitting device comprising a first and second LED on a substrate, with first and second photoluminescence material layers disposed over the LEDs, and a diffusing layer with light scattering particles over the photoluminescence layers, which enhances color uniformity and reduces the amount of photoluminescence material required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual coating of LED chips with photoluminescence material is used (CSP method), then color uniformity is improved, but manufacturing cost increases and manufacturing time increases
Solution Approach 1:
The device segments the photoluminescence materials into multiple layers (first photoluminescence material layer and second photoluminescence material layer) with different color temperatures, allowing each layer to contribute differently to the overall color output. This segmentation enables color tuning while using a simpler COB manufacturing process rather than individual chip coating.
Solution Approach 2:
The patent introduces a vertical stacking dimension by placing multiple photoluminescence material layers at different heights above the LED chips. The first photoluminescence material layer is positioned closer to the chips while the second layer is positioned higher, creating a three-dimensional structure that enables color control without requiring individual chip processing.
2Manufacturing precision
If individual coating of LED chips with photoluminescence material is used (CSP method), then color uniformity is improved, but manufacturing time increases
Solution Approach 1:
The patent merges multiple LED chips and multiple photoluminescence material layers into a single integrated COB structure. This combining approach allows all chips to be processed simultaneously in one manufacturing batch rather than coating each chip individually, dramatically reducing manufacturing time while maintaining color uniformity through the multi-layer design.
3Temperature
If excessive photoluminescence material is used to achieve desired color temperature, then color temperature control is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses partial action by employing two photoluminescence material layers with different color temperatures (first layer: 6000K-10000K, second layer: 2000K-4000K) in specific combinations. By selectively activating or adjusting the contribution of each layer, the system achieves precise color temperature control without requiring excessive amounts of photoluminescence material, thereby reducing manufacturing costs.
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 achieves enhanced color uniformity and reduced manufacturing costs by utilizing a diffusing layer with light scattering particles, which increases the conversion of LED light to photoluminescence light, thereby reducing the need for excessive photoluminescence material.
Implementation Method 1
white light emitting LEDs include one or more photoluminescence materials which absorb a portion of the excitation light emitted by the LED and re-emit light of a different color
Implementation Method 2
a diffusing layer disposed over the first and second photoluminescence layers, the diffusing layer comprising light scattering particles
Data Source
AI summary
An exemplary white light emitting device includes a plurality of LEDs disposed on a substrate, where the LEDs emit blue light at substantially the same correlated color temperature; a first photoluminescence material layer disposed over a first subset of the LEDs; a second photoluminescence material layer disposed over a second subset of the LEDs different from the first subset of the plurality of LEDs, the second photoluminescence material layer separate from the first photoluminescence material layer; and a diffusing layer separate from and disposed over the first and second photoluminescence layers, where the diffusing layer is associated with a plurality of light scattering particles.