Phosphor-Converted Emitter for High-CRI White Light Brightness
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Solution Overview
Problem
Current radiation-emitting devices fail to achieve enhanced brightness while emitting white light with a high color rendering index (CRI), particularly in converting blue light into infrared and visible light effectively.
Innovation Solution
The device incorporates a semiconductor chip emitting blue light, a down-converting phosphor converting blue light into red and infrared light, and an up-converting phosphor, specifically β-NaYF4 doped with lanthanoids, which converts infrared light into visible light, along with an organic dye enhancing energy transfer for broader infrared conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a down-converting phosphor converts blue light into infrared light, then the color rendering index is improved, but the brightness is reduced because infrared light is not visible to the human eye
Solution Approach 1:
An up-converting phosphor layer is introduced as an intermediary between the down-converting phosphor and the human eye. This intermediary layer converts the invisible infrared light back into visible light, allowing the infrared energy to contribute to both color rendering and perceived brightness simultaneously
Solution Approach 2:
The invention changes the wavelength parameter of the light twice: first down-converting from blue to infrared, then up-converting from infrared to visible. This dual parameter transformation allows the same energy to serve multiple functions - improving color rendering while maintaining brightness
2Illumination intensity
If an up-converting phosphor converts infrared light into visible light, then the brightness is enhanced, but the color rendering index may be compromised
Solution Approach 1:
The invention merges the functions of down-conversion and up-conversion phosphors into a single integrated system. The down-converting phosphor provides the infrared component for color rendering, while the up-converting phosphor simultaneously converts this infrared light to visible light for brightness enhancement, achieving both goals together
3Illumination intensity
If multiple phosphors are used for wavelength conversion, then the color rendering and brightness are improved, but the device complexity increases
Solution Approach 1:
The up-converting phosphor layer is positioned to receive infrared light from the down-converting phosphor layer, creating a nested structure where one phosphor layer is functionally embedded within the optical path of another. This nested arrangement allows multiple conversion functions to be achieved in a compact, integrated configuration rather than separate systems
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 significantly enhances the brightness of the radiation-emitting device by converting invisible infrared light into visible light, achieving a warm white impression with a high CRI and improved color temperature.
Implementation Method 1
a radiation-emitting semiconductor chip (1), emitting electromagnetic radiation of a first wavelength range B from a radiation exit surface (2)... the semiconductor chip (1) comprises a semiconductor layer sequence with an active zone (3) generating the electromagnetic radiation of the first wavelength range B
Implementation Method 2
a first phosphor (6) converting electromagnetic radiation of the first wavelength range B into electromagnetic radiation of a second wavelength range R
Implementation Method 3
an up-converting phosphor (8) converting infrared light of the second wavelength range R into visible light
Data Source
AI summary
A radiation-emitting device may include a radiation-emitting semiconductor chip configured to emit electromagnetic radiation of a first wavelength range from a radiation exit surface, a first phosphor configured to convert electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range. The second wavelength range may be or include infrared light. The device may further include an up-converting phosphor configured to convert infrared light of the second wavelength range into visible light.