Light Emitting Device Diffusion Layer Brightness Saturation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting devices with semiconductor laser light sources and phosphors experience local brightness saturation and temperature quenching when high-density laser light is collected and focused, leading to efficiency decreases due to brightness saturation and heat generation.
Innovation Solution
The light emitting device employs a diffusion layer to diffuse the excitation light, preventing local peak brightness distribution and incorporating reflection members to enhance light extraction efficiency, thereby avoiding brightness saturation and temperature quenching, and improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light is collected by a condenser lens and irradiated onto a phosphor in a spotlight manner, then light density is increased, but local brightness saturation and temperature quenching occur, decreasing efficiency
Solution Approach 1:
A diffusion layer is introduced as an intermediary component between the condenser lens and the phosphor. This diffusion layer receives the high-density laser light from the condenser lens and redistributes it uniformly across the phosphor surface, preventing local brightness saturation and temperature quenching while maintaining overall high light density for efficient wavelength conversion.
Solution Approach 2:
The optical path is segmented into distinct functional zones: the condenser lens focuses light to a small area, the diffusion layer divides and redistributes this concentrated light across a larger phosphor surface area, and the phosphor converts the distributed light to different wavelengths. This segmentation prevents harmful concentration of energy in one location.
2Power
If excitation density is increased to improve light output, then brightness saturation occurs, causing RF efficiency to abruptly decrease
Solution Approach 1:
The diffusion layer acts as a mediator that decouples the relationship between excitation density and phosphor illumination density. It allows high excitation density at the diffusion layer input (from the condenser lens) while maintaining optimal, non-saturating illumination density across the phosphor surface, thereby preserving RF efficiency at high power levels.
3Illumination intensity
If laser light is focused in a spotlight manner onto the phosphor, then light concentration is improved, but color unevenness occurs due to non-uniform excitation distribution
Solution Approach 1:
The diffusion layer serves as an intermediary that transforms the non-uniform spotlight excitation pattern from the condenser lens into a uniform illumination pattern across the phosphor. This ensures even excitation of the phosphor material, producing uniform wavelength-converted light and eliminating color unevenness while maintaining high overall light concentration.
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 allows for high-density laser light projection while preventing efficiency drops from brightness saturation and temperature quenching, suppressing color unevenness, and enhancing light extraction efficiency by diffusing excitation light and using reflection members to re-enter light into the wavelength conversion layer.
Implementation Method 1
The light emitting device employs a diffusion layer to diffuse the excitation light, preventing local peak brightness distribution
Implementation Method 2
a wavelength conversion member (for example, phosphor) in combination
Implementation Method 3
The phosphor 220 irradiated with the laser light can emit light as a result of excitation by the laser light
Implementation Method 4
incorporating reflection members to enhance light extraction efficiency, thereby avoiding brightness saturation and temperature quenching
Implementation Method 5
the laser light can be collected by the condenser lens 230 to pass through the through hole of the holder 240 and be projected on the phosphor 220
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light emitting device (10) can project high density laser light by collecting laser light to irradiate with light in a spotlight manner while remedying local brightness saturation and temperature quenching, and can suppress the lowering of efficiency due to such local brightness saturation and temperature quenching. The light emitting device (10) can include an excitation light source (14) for emitting excitation light; a wavelength conversion member (12) including a diffusion layer (30) and a wavelength conversion layer (32), the diffusion layer (30) having a first face (30a) and a second face (30b) opposite to the first face (30a), the diffusion layer (30) configured to diffuse excitation light that is irradiated onto the first face (30a) and cause the diffused light to exit through the second face (30b), the wavelength conversion layer (32) having a third face (32a) in contact with the second face (30b) and a fourth face (32b) opposite to the third face (32a), the wavelength conversion layer (32) configured to convert the excitation light incident on the third face (32a) in wavelength and cause the wavelength-converted light to exit through the fourth face (32b); and an optical system (16, 44) configured to collect the excitation light from the excitation light source (14) to irradiate the first face (30a) with the collected excitation light in a spotlight manner. In the light emitting device (10), the diffusion layer (30) can have a thickness that is set in such a manner that brightness distribution of the diffused light exiting through the second face (30b) does not include a local peak.