Hybrid LED Illumination System for High CRI and Efficacy
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Solution Overview
Problem
Existing lighting systems face challenges in achieving high luminous efficacy and color rendering index (CRI) over a wide range of correlated color temperatures (CCT) values, particularly due to inefficiencies in solely LED-based systems and the limitations of phosphor-LED systems, including the need for multiple stages of mixing and material costs.
Innovation Solution
A white light emitting device comprising a violet to blue LED, a phosphor material, and a red LED, where the phosphor absorbs radiation from the violet to blue LED and emits light in the green range, and the red LED has a peak emission greater than 615 nm, with the amber LED having a peak emission at least 25 nm greater than the red LED, to achieve high CRI and luminous efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If blue LED combined with yellow phosphor is used to produce white light, then luminous efficacy is improved, but color rendering index (CRI) deteriorates
Solution Approach 1:
The patent combines multiple LED types (blue LED with wavelength 430-470nm, green LED with wavelength 500-560nm, and red LED with wavelength 610-650nm) with yellow phosphor in a single illumination system. This merging of multiple light sources allows the system to maintain high luminous efficacy from the blue LED-phosphor combination while adding green and red spectral components to improve color rendering index to 80-85.
Solution Approach 2:
The patent uses a composite approach by combining multiple semiconductor materials (InGaN for blue and green LEDs, AlInGaP for red LEDs) with phosphor materials (YAG:Ce, TAG:Ce, or BOS). This composite material strategy enables the system to achieve both high efficiency and broad spectral coverage for improved color rendering.
2Manufacturing precision
If multiple LED mixing stages are used to achieve high CRI, then color rendering is improved, but efficiency deteriorates due to multiple mixing stages
Solution Approach 1:
The patent segments the illumination system into distinct functional modules: a blue LED module with yellow phosphor for high efficacy white light generation, a green LED module for filling the green spectral gap, and a red LED module for completing the spectral coverage. Each module operates independently at high efficiency, avoiding the cumulative efficiency losses of sequential mixing stages while achieving comprehensive spectral coverage for high CRI.
3Use of energy by moving object
If green LED efficiency is improved, then luminous efficacy is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by selecting specific wavelength ranges for each LED type that optimize their respective efficiencies: blue LEDs at 430-470nm, green LEDs at 500-560nm, and red LEDs at 610-650nm. By targeting these specific spectral regions where mature, efficient LED technologies exist, the patent achieves high overall luminous efficacy without encountering the manufacturing difficulties associated with less mature green LED technologies.
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 high luminous efficacy of at least 330 Im/Wopt and CRI of at least 80, with improved color control and stability across various CCT values, overcoming the inefficiencies of solely LED-based and phosphor-LED systems.
Implementation Method 1
a phosphor material radiationally coupled to the first LED; the phosphor converts the violet to blue light into green
Data Source
AI summary
A white light hybrid illumination system including an amber LED, a red LED, and a phosphor converted LED such as a blue LED chip and a green phosphor, wherein a peak emission difference between the amber and red LED is at least 25 nm. This system provides higher color quality than prior devices due to its high luminous efficacy, high CRI over a wide CCT range, and better color control.