LED Package Asymmetric Emitter Alignment for Light Coupling
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Solution Overview
Problem
Conventional LED packages suffer from reduced light coupling efficiency due to substantial reflections and recycling of light within the package, which decreases optical efficiency and increases heat production, limiting their brightness and reliability in applications like automotive lighting and digital micromirror devices.
Innovation Solution
The LED package design positions multiple emitters on a substrate such that their total emitting area is substantially equal to the total reflective area, with an optical axis non-parallel to the emitters' optical axis, allowing for increased light recapture and reduced heat generation, enhancing illumination intensity without increasing etendue, and achieves this without using additional lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED packages use traditional emitter positioning with parallel optical axes, then the structure is simple and easy to manufacture, but light coupling efficiency is reduced due to substantial reflections and recycling of light within the package
Solution Approach 1:
The patent positions multiple LED emitters with their optical axes substantially non-parallel to each other and non-parallel to the package optical axis, creating an asymmetric light emission pattern. This asymmetric arrangement prevents light from recycling back into the emitters through the substrate, thereby improving light coupling efficiency while maintaining manufacturing feasibility through standardized emitter mounting procedures
2Ease of manufacture
If conventional LED packages use traditional emitter positioning, then manufacturing is straightforward, but heat production increases due to reduced optical efficiency
Solution Approach 1:
By arranging emitters with non-parallel optical axes relative to the package optical axis, the patent optimizes light extraction efficiency. This asymmetric configuration reduces the amount of light trapped and recycled within the package, thereby improving overall optical efficiency and reducing waste heat generation without complicating the manufacturing process
3Loss of energy
If LED emitters are positioned with optical axes non-parallel to the package optical axis, then light coupling efficiency is improved, but the emitter positioning precision requirements increase
Solution Approach 1:
The patent specifies that the optical axes of the emitters be substantially non-parallel to the package optical axis, without requiring precise angular control. This partial action approach achieves sufficient light coupling efficiency improvement through the non-parallel arrangement itself, without demanding excessive manufacturing precision for exact angular positioning
Solution Approach 2:
The asymmetric positioning of emitters with non-parallel optical axes creates a geometric configuration that inherently improves light coupling efficiency. The asymmetry itself serves as the primary mechanism for reducing light recycling, eliminating the need for high-precision angular control and simplifying manufacturing requirements
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 configuration improves light coupling efficiency by up to 25% and reduces heat production, resulting in increased illumination intensity and longer lifespan, making LEDs more suitable for high-brightness applications like automotive lighting and digital displays.
Implementation Method 1
each of the LED emitters includes a reflective surface and a p/n junction located over the reflective surface
Implementation Method 2
LEDs typically include a PN junction diode semiconductor that emits photons when voltage is applied. This process of photon emission is called injection electroluminescence and occurs when electrons move from the N-type material to fill the lower energy holes that exist in the P-type material
Data Source
AI summary
One aspect of an LED package, which is covered by this disclosure, includes at least two LED emitters located on a substrate wherein each of the at least two LED emitters forms an emitting area. The emitting area is substantially equal to a reflective area of the LED package, and the LED package has an optical axis that is substantially non-parallel to an optical axis of each of the at least two LED emitters.