Blue LED Phosphor Conversion for High CRI SSL Lighting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid state lighting (SSL) luminaires struggle to achieve high color rendering index (CRI) and efficacy, especially at color temperatures between 2700 K and 4000 K, due to reliance on temperature-sensitive red LEDs and low conversion efficiency of red phosphors, which increases complexity and cost with compensation circuitry.
Innovation Solution
SSL luminaires that combine blue, yellow, and red light components using LED chips with specific conversion materials, such as blue LEDs coated with red or green phosphors, to produce white light without relying on temperature-sensitive red LEDs, thereby eliminating the need for complex compensation circuitry and enhancing emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SSL luminaires use temperature-sensitive red LEDs to achieve high CRI, then color rendering index is improved, but device complexity and cost increase due to compensation circuitry
Solution Approach 1:
The patent removes temperature-sensitive red LEDs from the system entirely, extracting the problematic component that required complex compensation circuitry. Instead, it uses only thermally stable blue LEDs with phosphor conversion materials (yellow, green, red phosphors) to generate the necessary spectral components, thereby eliminating the need for temperature compensation mechanisms while maintaining high CRI.
Solution Approach 2:
The patent changes the operational parameters by operating blue LEDs at wavelengths (430-480 nm) and temperatures where they exhibit thermal stability. By shifting from direct red LED emission to phosphor-based red light generation through blue LED excitation, the system achieves temperature insensitivity and eliminates the need for complex control circuitry.
2Illumination intensity
If conventional SSL luminaires use red phosphors with low conversion efficiency, then red light component is produced, but emission efficiency decreases
Solution Approach 1:
The patent introduces blue LEDs as an intermediary energy source that excites phosphor materials (yellow, green, and red phosphors) to generate the desired spectral components. This intermediary approach replaces direct red LED emission with phosphor conversion, achieving better overall emission efficiency by utilizing the high efficiency of blue LED generation and the favorable conversion characteristics of multiple phosphor materials.
3Temperature
If SSL luminaires combine multiple LED types to achieve desired color temperature, then color temperature control is improved, but device complexity increases
Solution Approach 1:
The patent makes blue LEDs universal by using them as the single light source type for all color temperature requirements. By varying the composition and proportions of phosphor materials (yellow, green, red phosphors) coated on the blue LEDs, the system achieves different color temperatures (2700K-4000K) without requiring multiple LED chip types or complex control circuitry, thereby simplifying the device architecture.
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
These luminaires produce consistent and efficient white light with desired color temperatures between 2700 K and 4000 K, improving CRI and reducing the complexity and cost associated with temperature compensation, while maintaining high emission efficiency.
Implementation Method 1
The yellow phosphor layer absorbs blue light from the blue LED and emits yellow light; the green phosphor layer absorbs blue light and emits green light; the red phosphor layer absorbs blue light and emits red light
Implementation Method 2
Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light
Data Source
AI summary
SSL lamps or luminaires are disclosed that combine blue, yellow (or green) and red photons or emissions to generate light with the desired characteristics. In different embodiments according to the present invention, the blue emission is not provided by an LED chip or package having a blue LED coated with a yellow phosphor, with blue light leaking through the yellow phosphor. Instead, the blue light component can be provided by other types of LED chips in the SSL luminaire such as one having a blue LED covered by a different colored conversion material, with blue light from the blue LED leaking through the different colored conversion material. In one embodiment, the blue component can be provided by an LED chip comprising a blue emitting LED covered by a conversion material that absorbs blue light and re-emits red light, with a portion of the blue light from the LED leaking through the red conversion material.