LED Encapsulant with Spatial Scatterer Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting diodes (LEDs) struggle with non-uniform color temperature and intensity profiles due to variations in light path lengths through conversion materials, leading to undesirable color variations when viewed from different angles, particularly in 'glob-in-a-cup' packaging methods and electrostatic deposition processes.
Innovation Solution
The use of an encapsulant with spatially varying light scattering properties, incorporating scattering particles and surface modifications to redirect light and achieve uniform emission profiles, ensuring consistent color temperature and intensity across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LEDs use phosphor conversion materials to generate white light, then white light emission is achieved, but non-uniform color temperature and intensity profiles occur due to variations in light path lengths
Solution Approach 1:
The encapsulant incorporates light scattering centers with spatially varying concentrations - higher concentration near the LED chip and lower concentration toward the periphery. This gradient distribution creates localized scattering effects that compensate for the longer light path lengths at the edges, ensuring uniform color temperature and intensity across the emission profile.
Solution Approach 2:
The patent modifies the optical parameters of the encapsulant by varying the concentration of light scattering particles (such as TiO2, SiO2, or ZrO2) throughout the encapsulant volume. This parameter change in scattering concentration directly addresses the non-uniformity caused by varying light path lengths through the phosphor conversion layer.
2Illumination intensity
If light scattering particles are added to the encapsulant, then spatial color temperature uniformity is improved, but the device complexity increases
Solution Approach 1:
The encapsulant is formulated as a composite material combining the base encapsulant matrix (transparent resin or silicone) with dispersed light scattering particles (TiO2, SiO2, ZrO2, or other oxides). This composite structure achieves the desired optical uniformity while maintaining a relatively simple single-component encapsulant geometry, avoiding the need for multiple discrete optical elements.
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 effectively randomizes the exit points of photons, resulting in improved spatial color temperature uniformity and tailored emission profiles, enhancing the performance of light emitting devices by minimizing color and intensity variations across different viewing angles.
Implementation Method 1
The encapsulant has light scattering properties that vary spatially in relation to the emission angle of light propagating through the encapsulant
Data Source
Figure 1a~1b
Figure 2~4
Figure 5~7
AI summary
A light emitting device having an encapsulant with scattering features to tailor the spatial emission pattern and color temperature uniformity of the output profile. The encapsulant is formed with materials having light scattering properties. The concentration of these light scatterers is varied spatially within the encapsulant and/or on the surface of the encapsulant. The regions having a high density of scatterers are arranged in the encapsulant to interact with light entering the encapsulant over a desired range of source emission angles. By increasing the probability that light from a particular range of emission angles will experience at least one scattering event, both the intensity and color temperature profiles of the output light beam can be tuned.