LED Spectrum Shift Compensation via Single Reference Channel
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Solution Overview
Problem
Thermal accumulation in LED light sources causes spectrum changes, making accurate color measurements challenging, especially in single-dimensional reference channel systems, which are costly to compensate for.
Innovation Solution
A system and method using a single reference channel with a processor, memory, and sensors to emit flashes of light, measure intensity at multiple wavelengths, and apply linear regression to generate a coefficient for correcting thermally dependent spectrum shifts, allowing for accurate color measurement without the need for multiple intensity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dual channel spectrophotometer with multiple LEDs and reference channel is used to compensate for thermal spectrum changes, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential function of wavelength monitoring from the complex reference channel system. Instead of using a full reference channel that monitors all wavelengths, the invention identifies and monitors only the specific wavelength (peak wavelength) that exhibits thermal drift. This extracted approach maintains measurement accuracy while dramatically simplifying the reference channel requirements.
Solution Approach 2:
The patent replaces expensive, complex reference channel hardware with a simple, inexpensive approach using basic spectral measurements and computational correction. The solution uses readily available spectral data and mathematical algorithms rather than costly additional optical components, achieving the same compensation function at much lower cost and complexity.
2Measurement precision
If a reference channel monitors intensity variation at each wavelength to compensate for LED spectrum change, then spectrum change compensation is improved, but the cost of the reference channel increases
Solution Approach 1:
The patent applies local quality by focusing monitoring efforts only where thermal drift occurs most significantly - at the peak wavelength of the LED spectrum. Rather than uniformly monitoring all wavelengths with equal precision, the invention concentrates measurement and correction resources on the critical peak wavelength region, achieving effective compensation with minimal reference channel requirements.
Solution Approach 2:
The patent replaces expensive reference channel hardware with inexpensive computational methods. By using basic spectral measurements combined with mathematical correction algorithms, the invention achieves spectrum change compensation without requiring costly additional optical components, detectors, or complex reference channel assemblies.
3Measurement precision
If multiple LEDs are used to generate spectrally-uniform illumination, then color measurement accuracy is improved, but thermal sensitivity and spectrum change increase
Solution Approach 1:
The patent implements feedback by continuously monitoring the peak wavelength of the LED spectrum and using this information to correct measurements in real-time. The system measures the actual spectral characteristics, compares them to reference values, and applies computational corrections to compensate for thermal drift, creating a closed-loop system that maintains accuracy despite temperature changes.
Solution Approach 2:
The patent addresses thermal sensitivity by changing the approach from preventing temperature changes to compensating for their effects. Instead of attempting to maintain constant LED temperature through complex thermal management, the invention allows temperature variations but compensates for resulting spectral shifts through wavelength-dependent correction factors and mathematical algorithms.
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 effectively compensates for thermal spectrum shifts in LED light sources, providing accurate and cost-effective color measurements by using a single reference channel, reducing flash-to-flash variability and improving measurement repeatability.
Implementation Method 1
This flash is reflected off of both the calibration target, and a reference target and measured by a sample sensor and a reference sensor respectively
Implementation Method 2
The sample sensor consists of an element such as a diffraction grating that splits the light incident on it from the sample into parts at a plurality of wavelengths
Implementation Method 3
when an LED is activated for an extended time, thermal accumulation on the P-N junction will cause a spectrum change in the light emitted by the LED
Implementation Method 4
Light emitting diodes are a widely used illumination source for obtaining accurate color measurements
Data Source
AI summary
In accordance with a broad aspect of the present invention the system and method described are directed to correcting with a single reference channel thermally dependent spectrum shifts of a light source used with a spectrophotometer. In one embodiment of the system and method described, a light measuring device uses the measured light intensity values to generate a correction coefficient for use in correcting measured light from an object under analysis.