LED Light Extraction Faces with Lumiphoric Materials
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Solution Overview
Problem
Conventional solid-state lighting devices, such as LEDs, face challenges in maximizing light emission efficiency due to omnidirectional light emission and optical losses associated with internal mirrors or reflectors, which can lead to absorption and reduced directional light output.
Innovation Solution
The design incorporates a primary and secondary light-extraction face with light-segregation elements and lumiphoric materials to allow omnidirectional light to exit freely, reducing optical losses and enhancing light emission efficiency by directing light through the use of reflective materials and encapsulant materials with light-affecting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If internal mirrors or reflectors are used to redirect light toward a desired direction, then light extraction efficiency in a desired direction is improved, but optical losses occur due to absorption by the reflective surfaces
Solution Approach 1:
The patent removes internal mirrors and reflectors from the LED chip structure, allowing light to exit through multiple faces without being redirected by reflective surfaces. This extraction of the problematic reflective elements eliminates the associated optical losses while maintaining light output through a different architectural approach.
Solution Approach 2:
Instead of redirecting light in a single primary direction using mirrors, the patent enables light to exit through multiple faces (top, bottom, and sidewalls) of the LED chip. This multi-dimensional light extraction approach distributes light output across different spatial dimensions, achieving high directional efficiency without reflective surfaces.
2Illumination intensity
If internal mirrors or reflectors are used to redirect light, then light emission efficiency is improved, but device complexity increases due to additional conductive and insulating features
Solution Approach 1:
The patent eliminates internal mirrors and reflectors from the LED chip, removing the complex network of conductive features, vias, and insulating layers that would be required to create and support these reflective elements. This simplification maintains emission efficiency through a cleaner architectural approach.
3Loss of energy
If omnidirectional light is allowed to exit freely through multiple faces, then optical losses are reduced, but light uniformity and directionality are compromised
Solution Approach 1:
The patent applies different optical properties to different faces of the LED chip. The top face maintains high light extraction efficiency for omnidirectional output, while the sidewalls are engineered with specific optical characteristics to provide directional control. This local differentiation allows each face to optimize for its specific function, achieving both low optical losses and controlled light directionality.
Solution Approach 2:
The patent modifies optical parameters such as refractive index, surface roughness, and emission characteristics of different LED chip faces to control light extraction. By adjusting these parameters locally on different surfaces, the device achieves optimized light uniformity and directionality while maintaining high extraction efficiency and minimizing optical losses.
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 improves light extraction and emission efficiency, providing uniform and directional light output with reduced glare and increased pixel-like resolution, suitable for both display and general illumination applications.
Implementation Method 1
at least one lumiphoric material arranged between different LEDs of the plurality of LEDs registered with the at least one light-segregation element, wherein the at least one lumiphoric material is arranged between the at least one light-segregation element and the secondary light-extraction face
Implementation Method 2
The design incorporates a primary and secondary light-extraction face with light-segregation elements and lumiphoric materials to allow omnidirectional light to exit freely, reducing optical losses and enhancing light emission efficiency by directing light through the use of reflective materials
Data Source
AI summary
Solid-state lighting devices, for example, light-emitting diodes (LEDs), which include a primary light-extraction face and a secondary light-extraction face that generally opposes the primary light-extraction face are disclosed. In some embodiments, mirrors internal to the LED may be omitted, and omnidirectional light from the active region is allowed to freely exit the primary light-extraction face and the secondary light-extraction face. In other embodiments, the first light-extraction face and second light-extraction face include opposing sidewalls of an LED. In such embodiments, mirrors internal to the LED may be utilized to direct omnidirectional light from the active region toward the first light-extraction face and the second light-extraction face.