TIR Extractor Element for White LED Light Extraction
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Solution Overview
Problem
Conventional white LEDs face challenges such as light-energy losses, phosphor self-heating, and degradation due to overheating, humidity, and undesired light propagation, which affect their efficiency and durability.
Innovation Solution
A light-emitting device with a total internal reflection (TIR) extractor element, featuring a transparent material with side surfaces shaped to reflect light at an angle equal to or greater than the critical angle for TIR, coupled with a light guide to optimize light output and reduce losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional white LEDs use phosphor down-conversion to generate white light, then the device can achieve white light emission with reduced complexity and better cost efficiency, but light-energy losses occur due to photon conversion and phosphor self-heating from Stokes loss
Solution Approach 1:
The patent extracts the harmful thermal effects and light-energy losses by introducing a TIR extractor element that separates the light extraction function from the phosphor conversion function. The extractor element captures and redirects light that would otherwise be lost, thereby reducing energy losses while maintaining the simplicity of phosphor-based white LED construction
Solution Approach 2:
The TIR extractor element acts as an intermediary component between the phosphor layer and the external environment. It mediates the interaction by capturing scattered light and redirecting it through total internal reflection, thereby reducing energy losses without interfering with the phosphor down-conversion process
2Illumination intensity
If phosphors are used for light conversion in white LEDs, then white light can be generated, but degradation occurs from changes of chemical and physical composition of phosphors due to overheating, humidity, and other damage
Solution Approach 1:
The TIR extractor element provides beforehand cushioning by creating a protective optical pathway that redirects light away from harmful thermal zones. By establishing total internal reflection at controlled interfaces, the system cushions the phosphors from direct exposure to overheating and humidity that would cause degradation
Solution Approach 2:
The extractor element serves as an intermediary barrier between the phosphor material and the harsh environmental conditions. It mediates the optical interactions while protecting the phosphors from direct exposure to humidity and thermal stress, thereby improving reliability
3Illumination intensity
If phosphors convert light through down-conversion, then white light is generated, but light propagates in undesired directions due to random emission of converted light from the phosphor
Solution Approach 1:
The TIR extractor element introduces dynamic light redirection by using angled side surfaces that actively redirect scattered light in controlled directions. The extractor dynamically adjusts the light pathway through total internal reflection, converting random emission into directed light output while maintaining white light generation
Solution Approach 2:
The patent applies dimensionality change by introducing angled side surfaces (e.g., 45-degree angles) that redirect light from the phosphor layer into a different spatial dimension. This transforms the random three-dimensional emission into a more controlled, directional output through geometric optimization
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 TIR extractor element enhances light extraction efficiency, reduces losses, and improves the durability and chromaticity of white LEDs by redirecting and recycling scattered light, leading to improved performance and longevity.
Implementation Method 1
an angle of incidence of light received from the light source that directly impinges on the at least a portion of the side surface is incident on the at least a portion of the side surface at an angle of incidence that is equal to or larger than a critical angle for total internal reflection
Data Source
AI summary
A variety of light-emitting devices are disclosed that are configured to output light provided by a light source. In general, embodiments of the light-emitting devices feature a light source and an extractor element coupled to the light source, where the extractor element includes, at least in part, a total internal reflection (TIR) surface. Luminaires incorporating light-emitting devices of this type are also disclosed.