Remote Phosphor Tube for High Efficacy LED Lighting
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Solution Overview
Problem
Conventional semiconductor light emitting devices struggle to achieve high luminous efficacy and color rendering index, particularly in producing white light with a color temperature between 2000 K and 8000 K, due to limitations in spectral power distribution and wavelength conversion efficiency.
Innovation Solution
Incorporating a wavelength conversion element with phosphor material in a semiconductor light emitting apparatus, where the light emitting diode is oriented to impinge upon the wavelength conversion element, enhancing light conversion efficiency and reducing backscattering, and using an elongated hollow wavelength conversion tube with uniformly or non-uniformly dispersed phosphor to achieve high lumens per watt output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple phosphor materials are used to achieve high color rendering index, then color accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple phosphor materials (yellow phosphor and red phosphor) within a single wavelength conversion element. This merging approach allows the element to convert blue LED light into a spectrum containing both yellow and red components, achieving high color rendering index without requiring separate conversion elements for each wavelength range.
Solution Approach 2:
The wavelength conversion element is designed to perform multiple functions simultaneously: it acts as both the yellow phosphor converter and the red phosphor converter in a single integrated structure. This multi-functionality reduces device complexity by eliminating the need for separate conversion elements while maintaining high color rendering performance.
2Loss of energy
If phosphor concentration is increased to improve wavelength conversion, then conversion efficiency is improved, but phosphor obstruction increases and reduces light output
Solution Approach 1:
The patent applies local quality by dispersing phosphor particles non-uniformly within the transparent medium. The phosphor concentration is optimized locally within the wavelength conversion element rather than being uniformly distributed, allowing sufficient conversion efficiency in regions where phosphor is present while maintaining light transmission in regions with lower phosphor concentration.
Solution Approach 2:
The patent transitions from a two-dimensional view (phosphor layer thickness) to a three-dimensional distribution approach. Phosphor particles are dispersed throughout the volume of the transparent medium in the wavelength conversion element, allowing light to interact with phosphor over an extended path length without encountering high local concentrations that would cause obstruction.
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 solution achieves greater than 230 lumens per watt at various color temperatures between 2000 K and 8000 K, with a high color rendering index of 80 or more, and reduces phosphor obstruction by optimizing the path length of light through the wavelength conversion material.
Implementation Method 1
The term 'wavelength conversion material' is used herein to refer to any material that absorbs light at one wavelength and re-emits light at a different wavelength
Implementation Method 2
The wavelength conversion material may include a yellow phosphor, such as cerium-doped yttrium aluminum garnet (YAG)
Implementation Method 3
Semiconductor light emitting devices ('LEDs'), such as light emitting diodes and laser diodes, are widely known solid-state lighting elements that are capable of generating light upon application of voltage thereto
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 230 lumens per watt.