Dual-Pump LED Phosphor Mix for Tunable Melanopic Lighting
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Solution Overview
Problem
Conventional phosphor-converted LEDs (pcLEDs) employing a royal-blue pump LED are not optimal for tunable lighting systems that require both a maximum tunable range of the melanopic to photopic (m/p) ratio and good color rendering, as the royal-blue emission peak overlaps with melanopic sensitivity, making it difficult to achieve both maximized and minimized m/p ratios while maintaining acceptable color fidelity.
Innovation Solution
A lighting device comprising a royal-blue light source and a blue light source, combined with a wavelength converting structure containing green and red phosphors, which absorbs and down-converts royal-blue and blue light to emit a second light with a higher m/p ratio, achieving a peak spectral power density between 447-531 nm and a correlated color temperature (CCT) of 4000K or greater, along with a color rendering index (Ra) greater than 80.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a royal-blue pump LED is used in a phosphor-converted LED, then the device can achieve high efficiency and narrow peak emission, but the emission peak overlaps with melanopic sensitivity making it difficult to achieve both maximized and minimized m/p ratios while maintaining acceptable color fidelity
Solution Approach 1:
The invention segments the light source into multiple independent LED chips with different peak wavelengths (violet 405nm, blue 450nm, cyan 495nm, green 530nm, yellow-green 560nm, red 630nm). Each LED chip can be independently controlled to emit at its peak wavelength, allowing the system to segment the spectral output and achieve precise m/p ratio tuning while maintaining color fidelity through selective wavelength combination.
2Adaptability or versatility
If phosphor materials are used to convert wavelength, then the emission spectrum can be adjusted, but the color rendering and m/p ratio control become compromised due to the fixed emission characteristics of phosphors
Solution Approach 1:
The invention changes the fundamental parameter approach from using fixed phosphor emission characteristics to using multiple LED chips with independently controllable peak wavelengths. By varying the drive currents to each LED chip, the system can dynamically adjust the spectral power distribution and m/p ratio while maintaining precise color fidelity through digital control of each wavelength component.
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 maximizes melanopic stimulation while maintaining high color fidelity, allowing for tunable lighting systems that can vary melanopic illuminance and minimize circadian disruption, with an m/p ratio greater than that of CIE daylight illuminant at corresponding CCT values.
Implementation Method 1
a green phosphor, the green phosphor configured to absorb a first portion of at least one of the royal-blue light and the blue light, and to down-convert the first portion to green light
Implementation Method 2
a red phosphor configured to absorb at least one of a second portion of at least one of the royal-blue light and the blue light and a portion of the green light and to down-convert the at least one of the second portion and the portion of the green light to red light
Data Source
AI summary
This specification discloses lighting device the includes a combination of a royal-blue and blue pump LEDs with a mixture of phosphors to provide light with a high melanopic content and maximize an m/p ratio while maintaining high color fidelity, and a tunable lighting system including the lighting device.