LED Optical Element With Reflective-Absorptive Layers for Heat Stability
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Solution Overview
Problem
High junction temperatures in light-emitting diodes (LEDs) cause polymer coatings to degrade, leading to reduced light emission performance and inconsistent display appearances in multi-LED systems.
Innovation Solution
An optical element with a reflective surface for specific light spectra and an absorptive surface for another spectrum, composed of metal and dielectric layers, is used to manage light emission and absorption, preventing degradation at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer coating is used on LED to control light emission, then light emission performance can be controlled, but the polymer degrades at high junction temperatures leading to reduced reliability
Solution Approach 1:
The patent uses a composite optical element comprising a transparent substrate with multiple coating layers including dielectric layers and reflective layers. This composite structure replaces the single polymer coating, providing both optical control and thermal stability. The dielectric layers (e.g., SiO2, Si3N4, TiO2) and reflective layers (e.g., Al, Ag, Au) are deposited on the substrate to create a multi-layer composite that withstands high junction temperatures while controlling light emission.
2Stability of the object's composition
If polymer coating is used to control light emission, then light direction can be managed, but appearance consistency deteriorates in multi-LED systems due to degradation
Solution Approach 1:
The patent employs a composite optical element with transparent substrate, dielectric layers, and reflective layers that maintains stable optical properties at high operating temperatures. This composite structure prevents the degradation issues seen in polymer coatings, ensuring consistent appearance across multiple LEDs in displays. The inorganic materials used in the composite structure do not degrade like organic polymers, maintaining stable light emission characteristics.
Solution Approach 2:
The patent optimizes the thickness parameters of each layer in the composite optical element to control light emission characteristics. By carefully selecting and adjusting the thickness of dielectric layers and reflective layers, the system achieves desired optical performance while maintaining stability at high temperatures. This parameter optimization ensures consistent appearance across multi-LED systems.
3Use of energy by moving object
If optical element with reflective and absorptive surfaces is used, then light emission efficiency improves, but device complexity increases
Solution Approach 1:
The optical element serves multiple functions within a single integrated structure: the transparent substrate provides mechanical support and light transmission, dielectric layers provide optical control and protection, and reflective layers redirect light. This multi-functional design improves light emission efficiency while avoiding the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The optical element is segmented into distinct functional layers (transparent substrate, dielectric layers, reflective layers), each performing a specific optical function. This segmentation allows for optimized performance of each layer while maintaining an integrated structure that can be manufactured as a single unit, balancing complexity with functionality.
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 solution enhances light emission efficiency and maintains consistent appearance in LED displays by reflecting desired light and absorbing unwanted light, improving brightness and energy efficiency while withstanding high temperatures.
Implementation Method 1
a first surface of the optical element, which contacts the light emission surface, is configured to reflect light associated with the first optical spectrum
Implementation Method 2
a second surface of the optical element, opposite the first surface of the optical element, is configured to absorb light associated with a second optical spectrum
Data Source
Figure 1A
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AI summary
An emitter includes a light emission region configured to emit light associated with a first optical spectrum, a light emission surface, and an optical element disposed on the light emission surface. A first surface of the optical element, which contacts the light emission surface, is configured to reflect light associated with the first optical spectrum. A second surface of the optical element, opposite the first surface of the optical element, is configured to absorb light associated with a second optical spectrum. At least one aperture is formed in the optical element.