Patterned Phosphor LED Array for Uniform Multi-Color Light Output
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Solution Overview
Problem
Current phosphor-converted LED arrays suffer from non-uniform light projection due to dark gaps and color variations across the light source, which are typically addressed using diffusers or secondary optics, but these solutions do not fully eliminate the issue of color over angle and source variation.
Innovation Solution
A patterned converter layer with two or more different phosphor regions is applied over the LED arrays, where the first region converts light to a warm white color and the second region converts light to a cooler white color, improving light uniformity by adjusting the converter material concentration and path length to match the color of light emitted from different angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single phosphor converter layer is used over LED arrays, then the device structure is simple, but the light projection becomes non-uniform with dark gaps and color variations
Solution Approach 1:
The patent applies local quality by dividing the converter layer into multiple regions with different phosphor materials or concentrations. Each region is positioned to compensate for specific optical deficiencies in corresponding LED areas, creating locally optimized light output that collectively achieves uniform overall illumination.
Solution Approach 2:
The converter layer is segmented into multiple distinct regions rather than using a uniform layer. This segmentation allows different phosphor materials to be placed in specific zones to address dark gaps and color variations, transforming a single-function layer into a multi-functional compensation structure.
2Illumination intensity
If diffusers or secondary optics are added to address non-uniform light projection, then light uniformity improves, but the device complexity and loss of energy increase
Solution Approach 1:
The patent merges the function of color correction and uniformity compensation directly into the converter layer itself, eliminating the need for separate diffusers or secondary optics. By integrating multiple phosphor regions with different properties into a single converter structure, it achieves both color balance and uniformity without additional optical components.
Solution Approach 2:
The multi-region converter layer performs multiple functions simultaneously: it converts LED wavelengths, compensates for dark gaps, corrects color variations, and ensures uniform light projection. This single multi-functional structure replaces what would traditionally require multiple separate components.
3Illumination intensity
If phosphor concentration is increased to improve light conversion, then the color rendering improves, but the light path length increases causing color over angle variation
Solution Approach 1:
Different phosphor regions are designed with locally optimized concentrations and materials. Regions experiencing different optical path lengths have adjusted phosphor properties to compensate, ensuring that light viewed from different angles maintains consistent color characteristics.
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 enhances the uniformity of light projection, reduces the need for additional diffusers, and allows for tunable lighting systems that can seamlessly transition between warm and cool white colors without visible pixelation, resulting in a more consistent and efficient light output.
Implementation Method 1
a patterned converter layer with two or more different phosphor regions is applied over the LED arrays, where the first region converts light to a warm white color and the second region converts light to a cooler white color
Data Source
AI summary
A lighting device is disclosed that includes a plurality of light emitting diodes arranged in an array, a plurality of trenches disposed between and optically isolating the light emitting diodes, and a patterned converter layer disposed over an array surface formed by light emitting surfaces of the light emitting diodes and upper surfaces of the trenches, the patterned converter layers including a first region having a first converter and a second region having a second converter different from the first converter, the first region and second region disposed over different areas of the array surface.