Segmented Phosphor Layers for LED Modules
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Solution Overview
Problem
Conventional light-emitting devices using blue LEDs with green and red phosphors suffer from reduced luminescence intensity due to light refraction and absorption issues at the boundary between phosphor layers, leading to quenched green light and decreased overall luminescence.
Innovation Solution
A light-emitting module design featuring phosphor layers divided into regions with different peak fluorescence wavelengths, where the first phosphor region emits longer wavelength light than the second, arranged alternately to prevent interference with light extraction, reducing Stokes loss and enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If green phosphor and red phosphor are used together in a light-emitting device, then color rendering is improved, but green light is quenched by the red phosphor absorbing it
Solution Approach 1:
The phosphor layer is segmented into multiple distinct layers: a green phosphor layer and a red phosphor layer arranged in sequence. This segmentation prevents the red phosphor from absorbing green light by spatially separating the two phosphor materials, thereby eliminating the quenching effect while maintaining color rendering improvement.
2Loss of energy
If green phosphor layer is formed on red phosphor layer, then green light quenching is solved, but light refraction and reflection at the boundary reduce luminescence intensity
Solution Approach 1:
A resin layer is introduced as an intermediary between the green phosphor layer and the red phosphor layer. This resin layer acts as an optical coupling medium that reduces refraction and reflection at the phosphor layer boundaries, thereby minimizing light loss and maintaining high luminescence intensity while preserving the quenching prevention effect.
3Ease of manufacture
If multiple phosphor layers are stacked, then color rendering is enhanced, but light extraction efficiency decreases due to boundary refraction and absorption
Solution Approach 1:
Resin layers are placed between adjacent phosphor layers to serve as optical intermediaries. These resin layers have refractive indices that bridge the gap between different phosphor materials, reducing refraction and reflection losses at each boundary and improving overall light extraction efficiency while maintaining the multi-phosphor color rendering enhancement.
Solution Approach 2:
The refractive index parameter of the phosphor layers is optimized by selecting appropriate resin materials with suitable refractive indices for the intermediate layers. This parameter change reduces optical impedance mismatch between layers, minimizing refraction and reflection losses and improving light extraction efficiency.
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 suppresses luminescence intensity reduction, improving the color rendering and efficiency of light-emitting modules by minimizing light interference and absorption, resulting in higher luminescence intensity and uniform color output.
Implementation Method 1
Each of the phosphor layers includes a phosphor that absorbs light emitted from the light-emitting element and emits fluorescence
Implementation Method 2
a blue LED 104 mounted on a conductor pattern 103 that is provided on the sub-mount substrate 102
Data Source
AI summary
A light-emitting module (1) includes a substrate (10), a plurality of light-emitting elements (14) formed on the substrate (10), and phosphor layers (15) covering each of the light-emitting elements (14). Each of the phosphor layers (15) includes a first phosphor region (15a) and a second phosphor region (15b) that are divided in the direction substantially parallel to the surface of the substrate (10). Each of the first phosphor region (15a) and the second phosphor region (15b) includes a phosphor that absorbs light emitted from the light-emitting element (14) and emits fluorescence. The maximum peak wavelength of fluorescence emitted from the first phosphor region (15a) is longer than that of fluorescence emitted from the second phosphor region (15b).