Solid State Lighting Apparatus High S/P Ratio
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Solution Overview
Problem
Conventional solid state lighting devices face challenges in achieving high scotopic/photopic ratio (S/P ratio) and color rendering index (CRI) simultaneously, while maintaining high luminous efficacy and brightness, due to the trade-off between these parameters and the reduced efficacy of long-wavelength blue and green emitters.
Innovation Solution
The use of blue electrically activated solid state light emitters, in combination with green and red lumiphors, to generate aggregate emissions with a S/P ratio of at least 1.95, incorporating specific peak wavelengths and lumiphoric materials to enhance color rendering and brightness, and allowing for independent control of red emitters to optimize output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If long-wavelength blue and green solid state emitters are used to increase S/P ratio, then scotopic/photopic ratio is improved, but luminous efficacy deteriorates
Solution Approach 1:
The patent divides the solid state emitter array into multiple segments with different peak wavelengths (430-455nm, 456-469nm, 600-650nm) that can be independently controlled. This segmentation allows optimization of each wavelength's contribution to achieve high S/P ratio while maintaining overall luminous efficacy through selective activation of emitters based on operational requirements
Solution Approach 2:
The patent changes the operational parameters by independently controlling the drive current to different solid state emitters. By adjusting the intensity of each wavelength component (blue at 430-455nm, blue at 456-469nm, and red at 600-650nm), the system optimizes the S/P ratio while compensating for the reduced efficacy of long-wavelength emitters through enhanced short-wavelength emission
2Illumination intensity
If multiple solid state emitters with different wavelengths are combined to achieve high S/P ratio, then scotopic/photopic ratio is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple solid state emitters with different peak wavelengths onto a single substrate, creating an integrated multi-wavelength light source. This combining approach achieves high S/P ratio functionality while consolidating what could have been separate devices into one unified structure, thereby managing complexity through integration rather than multiplication of discrete components
Solution Approach 2:
The patent creates a universal solid state lighting device that can simultaneously provide illumination with high S/P ratio, adjustable color temperature, and high luminous efficacy. The multi-functional design allows the same device structure to optimize for different operational modes (daylight simulation, energy efficiency, color rendering) without requiring separate specialized devices for each function
3Illumination intensity
If blue and green emitters are used to achieve high S/P ratio, then scotopic/photopic ratio is improved, but color rendering index deteriorates
Solution Approach 1:
The patent applies local quality by adding a red emitter component (600-650nm) to specifically address the color rendering deficiency caused by blue-green dominant emission. This localized addition of red wavelength content improves the spectral power distribution in the red region, thereby enhancing color rendering index without compromising the high S/P ratio achieved through blue emitter optimization
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
This approach results in lighting devices with high S/P ratio, high CRI, and high luminous efficacy, providing improved color rendering and energy efficiency, while maintaining brightness and flexibility in configuration.
Implementation Method 1
A solid state lighting device may include, for example, at least one organic or inorganic light emitting diode ("LED")
Implementation Method 2
at least one first electrically activated solid state light emitter, and at least one second electrically activated solid state light emitter
Implementation Method 3
a first lumiphoric material... arranged to receive spectral output from the at least one first electrically activated solid state light emitter and the at least one second electrically activated solid state light emitter
Data Source
AI summary
Solid state light emitting apparatuses include blue LEDs (e.g., including short wavelength and long wavelength blue LEDs in combination) to stimulate green lumiphors, with supplemental emissions by red lumiphors and/or red solid state light emitters, to provide aggregate emissions with high S/P ratio (e.g., ≧1.95) and high color rendering values (e.g., ≧85), preferably in combination with high brightness and high luminous efficacy. In certain embodiments, a light emitting apparatus may be devoid of a LED having a peak wavelength of from 470-599 nm and/or devoid of lumiphors with peak wavelengths in the yellow range. Multiple LEDs may be arranged in an emitter package. A fabrication method includes mounting multiple solid state emitters (e.g., with a first blue and a second red emitter) to a common substrate, applying a stencil or mask over the second emitter, applying a lumiphoric material over the first emitter, and removing the stencil or mask.