Narrow-band Light Source with Non-overlapping Spectral Peaks
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Solution Overview
Problem
Current light sources with semiconductor devices, such as LEDs and OLEDs, often lack sufficient color contrast due to their limited spectral bandwidth, which is not adequately addressed by existing technologies, impacting applications like surgical illumination and advertising where enhanced visibility is crucial.
Innovation Solution
A light source comprising two narrow-band emitters with different central emission wavelengths within the blue, green, or red color-range, utilizing luminescent materials like quantum dots or rare-earth metal complexes to generate non-overlapping narrow spectral peaks, ensuring significant color contrast by tuning the central emission wavelength for enhanced visibility of specific elements or branding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If semiconductor light emitting devices (LEDs, OLEDs) are used to improve light source efficiency, then energy efficiency is improved, but color contrast deteriorates
Solution Approach 1:
The invention divides the light emission into multiple discrete narrow spectral peaks using separate luminescent materials (e.g., quantum dots with different core sizes) instead of a single broad spectrum source. This segmentation of the spectrum into distinct bands enables both high efficiency (through targeted LED excitation) and high color contrast (through non-overlapping emission bands).
Solution Approach 2:
The invention uses composite luminescent material systems comprising multiple quantum dot types (e.g., CdSe core with different shell materials like ZnS, CdS, or ZnSe) or combinations of quantum dots with rare-earth metal complexes. These composite materials enable simultaneous achievement of narrow bandwidth for contrast and efficient LED coupling for energy savings.
2Illumination intensity
If luminescent materials are included to improve color rendering, then color rendering is improved, but color contrast deteriorates
Solution Approach 1:
The invention applies different luminescent materials with specific properties to different spectral regions. Each quantum dot or rare-earth complex is selected for its narrow emission bandwidth and specific peak wavelength, creating local spectral optimization rather than uniform broad-spectrum emission. This local quality approach maintains good overall color rendering while achieving superior contrast in specific color bands.
Solution Approach 2:
The invention changes the key parameter of luminescent material selection from broad-spectrum phosphors to narrow-band quantum dots and rare-earth complexes. By controlling the core size and composition of quantum dots (which directly determines emission wavelength) and selecting specific rare-earth metal complexes, the invention achieves both adequate color rendering and high color contrast simultaneously.
3Ease of manufacture
If narrow spectral peaks are generated using luminescent materials, then color contrast is improved, but device complexity increases
Solution Approach 1:
The invention merges multiple luminescent materials into a single integrated light source assembly that can be excited by a single LED or LED array. The quantum dots and rare-earth metal complexes are combined in a common phosphor layer or separate layers that are all excited by the same blue or UV LED, simplifying the overall device structure while maintaining multiple narrow spectral peaks.
Solution Approach 2:
The invention uses quantum dots and rare-earth metal complexes as intermediary materials that convert the broad-spectrum LED emission into multiple narrow spectral peaks. These intermediary luminescent materials absorb LED photons and re-emit at specific narrow wavelengths, enabling high color contrast without requiring multiple separate LED sources or complex optical systems.
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 significantly enhances color contrast in the visible spectrum, improving the visibility of surgical instruments, branding, and hidden information, without the need for contrast fluids during surgery or additional lighting, while maintaining good color rendering across the visible range.
Implementation Method 1
At least one of the two narrow-band light emitters comprises a luminescent material for generating the narrow spectral peak
Implementation Method 2
Typically the absorbed photons are emitted as photons having a lower frequency (or longer wavelength: Stokes shift)
Implementation Method 3
Alternatively, the emitted photons may have higher frequency (or shorter wavelength: anti-Stoke shift)
Implementation Method 4
utilizing luminescent materials like quantum dots or rare-earth metal complexes to generate non-overlapping narrow spectral peaks
Data Source
AI summary
The Invention provides a light source, a luminaire and a surgical illumination unit in which two narrow-band light emitters both emit light in a narrow spectral peak having a full-width-half-maximum equal to or smaller than 40 nanometers. Both of the narrow-band light emitters have a different central emission wavelength within a blue color-range, within a green color range or within a red color-range. At least one of the two narrow-band light emitters comprises a luminescent material for generating the narrow spectral peak. The light source is further configured such that a distance between the narrow spectral peaks of the two narrow-band light emitters prevents overlap of the narrow spectral peaks. Due to the individual narrow spectral peaks, a color contrast within one of the color-ranges is significantly enhanced.