LED Waveguide Directing Light via Total Internal Reflection
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Solution Overview
Problem
Conventional semiconductor LEDs emit light in all directions, leading to inefficiencies in light output as only a fraction escapes the package, necessitating techniques to redirect light in desired directions for improved efficiency.
Innovation Solution
The development of an LED structure and package that incorporates a substrate, multiple layers, a reflector, and a waveguide system with an adjustable shutter to direct light in two or more desired directions, allowing for controlled light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED structures emit light in all directions, then light generation is simple, but light extraction efficiency is low
Solution Approach 1:
The LED structure is segmented into multiple functional layers including a substrate, first layer, active layer, and second layer. Additionally, the light extraction system is segmented into a reflector and a waveguide, allowing light to be directed in multiple specific directions rather than all directions, thereby improving light extraction efficiency while maintaining manageable structural complexity through modular design
Solution Approach 2:
A waveguide is introduced as an intermediary component between the LED active layer and the external environment. The waveguide, positioned below the substrate and aligned with apertures in the reflector, mediates the transmission of light in specific directions (first and second directions), enabling controlled light extraction without requiring the LED structure itself to be overly complex
2Illumination intensity
If a reflector is used to redirect light, then light output in desired direction increases, but device complexity increases
Solution Approach 1:
The reflector and waveguide are merged into a coordinated light management system. The reflector redirects light upward toward the substrate, while the waveguide, positioned below the substrate with apertures aligned to the reflector, transmits light in specific downward directions. This merging of components achieves high illumination intensity in desired directions while consolidating the light control function into an integrated package structure
Solution Approach 2:
The waveguide serves multiple functions: it acts as a structural support element below the substrate, provides a pathway for light transmission in specific directions, and works in conjunction with the reflector to achieve comprehensive light control. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity
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 enhances light output by enabling simultaneous emission in multiple directions, improving light extraction efficiency and versatility in various applications such as flashlights, display backlighting, and computing devices.
Implementation Method 1
at least one waveguide formed below the substrate. A first portion of light from the LED is directed in a first direction and a second portion of light from the LED is directed in a second direction via the waveguide
Implementation Method 2
In order to increase light output, techniques for reflecting light emitted from the substrate in a desired direction are typically used
Data Source
AI summary
A light-emitting diode (LED) apparatus comprises a substrate, a first layer formed over at least a portion of the substrate, an active layer formed over at least a portion of the first layer, a second layer formed over at least a portion of the active layer, and at least one waveguide formed below the substrate. A first portion of light from the LED is directed in a first direction and a second portion of light from the LED is directed in a second direction via the waveguide, the second direction being different than the first direction. The apparatus may further comprise a shutter formed at least one of above and below the waveguide, the shutter being adjustable to control an amount of light entering or exiting the waveguide.