Remote Phosphor Light Emitting Diodes for High Efficacy White Light
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Solution Overview
Problem
Conventional semiconductor light emitting devices struggle to produce white light with high color rendering index and luminous efficacy, particularly in wavelength ranges where efficiency is difficult to achieve, such as around 550 nm.
Innovation Solution
A semiconductor light emitting apparatus incorporating a wavelength conversion element with wavelength conversion material and a plurality of light emitting diodes oriented to emit light onto the conversion element, which includes a substrate, a transparent outer shell, and an optical material, such as phosphor, to enhance light emission efficiency and color rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple LEDs emitting light of different colors are used to produce white light, then color rendering index is improved, but luminous efficacy deteriorates due to narrow spectral power distributions and gaps in wavelength coverage
Solution Approach 1:
The patent uses a single blue LED with fixed wavelength parameters and changes the phosphor material parameters (composition, particle size, concentration) to achieve different color temperatures and maintain high efficacy. This resolves the contradiction by keeping the efficient blue LED unchanged while optimizing the wavelength conversion material properties
Solution Approach 2:
The patent introduces phosphor particles as an intermediary substance between the blue LED and the human eye. The phosphor converts part of the blue light to yellow light, and the mixture appears white to observers. This intermediary enables high efficacy white light without requiring multiple inefficient LEDs across different wavelength gaps
2Use of energy by moving object
If wavelength conversion material is applied directly to the LED to convert blue light to white light, then luminous efficacy is improved, but color rendering index deteriorates due to insufficient spectral coverage
Solution Approach 1:
The patent applies phosphor particles with specific local properties (yellow-emitting characteristics) at specific locations (remote from the LED chip) to achieve the desired spectral quality. By positioning the phosphor remotely and using particles with optimized properties, the system maintains high efficacy while improving color rendering through selective wavelength conversion
3Device complexity
If phosphor particles are used to convert blue LED light to white light, then device complexity is reduced, but manufacturing precision deteriorates due to challenges in achieving uniform phosphor distribution and coating
Solution Approach 1:
The patent uses inexpensive phosphor particles that can be easily applied and discarded if needed, rather than complex integrated wavelength conversion structures. The particles are applied as a coating that can be optimized for uniformity through simple processes like dip coating or spray application, reducing manufacturing precision requirements while maintaining structural simplicity
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 apparatus achieves greater than 250 lumens per watt at a color temperature of 2000 K to 8000 K, with some embodiments producing up to 270 lumens per watt, while maintaining a high color rendering index of 80 or more, enabling efficient white light production.
Implementation Method 1
a wavelength conversion element comprising wavelength conversion material, and a plurality of light emitting diodes that are oriented to emit light to impinge upon the wavelength conversion element
Data Source
AI summary
A semiconductor light emitting apparatus a semiconductor light emitting device configured to emit light inside a hollow shell including wavelength conversion material dispersed therein or thereon. A semiconductor light emitting apparatus according to some embodiments is capable of generating in excess of 250 lumens per watt, and in some cases up to 270 lumens per watt.