Blue LED Red Fluorescent Light Extraction
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Solution Overview
Problem
Conventional red-color LEDs exhibit poor temperature characteristics, leading to reduced output at high temperatures, necessitating the development of more efficient light emission devices that can maintain performance across varying temperatures.
Innovation Solution
A light emitting device comprising a blue-color light emitting element, a fluorescent material layer, a reflective film, a light-transmissive member, and an absorbing layer, where the fluorescent material layer converts blue-color light to red-color light, the reflective film enhances light extraction, and the absorbing layer reduces light leakage, thereby improving light emission efficiency and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a red-color LED is used as a light source, then red-color light emission is achieved, but the output is reduced under high temperatures due to poor temperature characteristics
Solution Approach 1:
A blue-color LED is used as an intermediary light source to excite a red-color fluorescent material, which then emits red-color light. This mediator approach allows the system to achieve red-color light emission without using a red-color LED directly, thereby avoiding the temperature characteristic problems of red-color LEDs while maintaining reliable red light output across varying temperatures.
2Illumination intensity
If a dielectric multilayer film reflecting blue-color light is provided between a blue-color LED and a red-color fluorescent material layer, then light emission efficiency of red-color light is improved, but the device structure becomes more complex
Solution Approach 1:
The patent utilizes the color conversion property of fluorescent materials, where a blue-color LED excites a red-color fluorescent material to emit red-color light. This color change mechanism simplifies the device structure by eliminating the need for complex blue-light reflecting dielectric multilayer films, while still achieving high red-color light emission efficiency through the inherent fluorescent conversion process.
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 device achieves enhanced light emission efficiency and color purity by effectively converting blue-color light to red-color light, maintaining performance across temperatures and reducing light leakage, resulting in a more reliable and efficient light emitting solution.
Implementation Method 1
The fluorescent material layer is excited by the first light to emit second light being longer in wavelength than the first light
Implementation Method 2
The reflective film is disposed on the fluorescent material layer to reflect part of the first light and transmit the second light
Implementation Method 3
The absorbing layer is disposed on the light-transmissive member to absorb part of the first light
Data Source
AI summary
A light emitting device according to one embodiment of the present disclosure includes a light emitting element, a fluorescent material layer, a reflective film, a light-transmissive member, and an absorbing layer. The light emitting element emits first light. The fluorescent material layer is disposed on the light emitting element. The fluorescent material layer is excited by the first light to emit second light being longer in wavelength than the first light. The reflective film is disposed on the fluorescent material layer to reflect part of the first light and transmit the second light. The light-transmissive member is disposed on the reflective film. The absorbing layer is disposed on the light-transmissive member to absorb part of the first light. The light emitting element is identical in area to or smaller in area than the fluorescent material layer in a plan view.