Multispectral LED Daylight Simulation with Autocalibration
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Solution Overview
Problem
Current color matching systems, particularly in the graphics industry, face challenges with fluorescent lamps that have broad tolerances and aging issues, leading to inaccurate color reproduction and the need for multiple lighting devices to accommodate different light conditions, while LED-based solutions fail to simulate high-quality daylight spectra effectively due to incomplete spectral coverage.
Innovation Solution
A method using multiple LEDs grouped to emit specific spectra, with tristimulus values calculated and stored for precise actuation, allowing for simulation of any desired daylight spectrum along the Planckian locus, and a multispectral color coordination system with measurement and autocalibration capabilities to maintain high-quality light simulation across a wide color temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorescent lamps are used for color matching, then color reproduction meets current ISO standards, but spectral distribution has multiple peaks leading to broad tolerances and aging issues
Solution Approach 1:
The patent divides the continuous spectrum into multiple discrete wavelength bands (380-780nm divided into 7-10 LED groups), with each LED emitting at a specific wavelength range. This segmentation allows precise control over spectral distribution, eliminating the broad tolerances inherent in fluorescent lamps while achieving accurate color reproduction.
Solution Approach 2:
The patent changes the fundamental parameter of light emission from fluorescent phosphor conversion (broad spectrum with peaks) to direct LED emission (narrow bandwidth). By adjusting LED current and combining multiple LEDs with different peak wavelengths, the system achieves precise spectral control without aging issues associated with fluorescent materials.
2Duration of action of stationary object
If LED-based solutions are used, then useful lifetime is extended and robustness improved, but spectral coverage is incomplete failing to simulate high-quality daylight
Solution Approach 1:
The patent combines multiple LEDs with different peak wavelengths (violet 405nm, blue 450nm, cyan 490nm, green 530nm, yellow-green 560nm, red 630nm) into a single illumination system. This merging of discrete spectral components creates a composite spectrum that closely matches daylight, overcoming the limitation of individual LEDs having incomplete spectral coverage.
Solution Approach 2:
The patent creates a composite light source by integrating multiple LED types with complementary spectral characteristics. Each LED contributes a specific portion of the spectrum, and their combined output forms a composite spectrum that achieves high-quality daylight simulation while maintaining LED longevity and robustness.
3Manufacturing precision
If multiple LEDs with different wavelengths are used, then spectral coverage is improved, but device complexity increases
Solution Approach 1:
The patent designs a control system that serves multiple functions: it individually controls each LED's intensity, calculates combined spectral output, compares against target spectra, and adjusts in real-time. This multi-functional approach manages the complexity of multiple LEDs through a unified control architecture rather than separate control circuits for each LED.
Solution Approach 2:
The patent implements a feedback mechanism where the actual combined spectrum of multiple LEDs is measured and compared against the target daylight spectrum. The control system uses this feedback information to adjust individual LED intensities, automatically optimizing spectral distribution and simplifying the management of multiple LED components.
4Reliability
If fluorescent lamps are used, then current color matching standards are met, but metamerism occurs under different light conditions
Solution Approach 1:
The patent changes from using broad-spectrum fluorescent light to narrow-band LED emission, allowing precise control over which wavelengths are present. By selectively activating specific LEDs and adjusting their intensities, the system can create illumination spectra that minimize metamerism while maintaining accurate color rendering across different viewing conditions.
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 stable, high-quality daylight simulation, meeting international standards with a color reproduction index above 90 and low metamerism indices, enabling precise color matching and extending the useful lifetime of LED light sources, thus reducing costs and environmental impact.
Implementation Method 1
producing light by means of a plurality of LEDs disposed in groups, whereby each group is formed from LEDs positioned in compact manner next to one another, and the LEDs within each group emit light at different wavelengths
Implementation Method 2
measuring the spectra of the light emitted by each individual LED at different predetermined working temperatures, calculating the tristimulus values XYZ (CIE1931 2°) for each measured temperature range
Data Source
AI summary
A method and a multispectral color coordination system simulates high-quality daylight spectra. Light is produced with LEDs disposed in groups. Each group emits light at different wavelengths within the daylight spectrum. The wavelength of the light emitted by each LED at different working temperatures and different PWM values is measured. The measurement results for each LED are stored in memory, with assignment to working temperatures and PWM values. The LEDs are actuated at values selected from the memory content, as a function of the light to be emitted by each group. The working temperature of each individual LED chip is constantly measured and compared with the values stored in memory with regard to the current working temperature, and, in case of deviation compensated for by recalculating the spectrum, taking into consideration the PWM values stored in memory for the working temperature, and actuating with these.