LED Driver Calibration Using Stored Spectral Data
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Solution Overview
Problem
Conventional LED light fixtures face challenges in achieving uniform and consistent spectral characteristics due to manufacturing variability and limited color production capabilities, leading to difficulties in reproducing desired colors across different fixtures and manufacturers.
Innovation Solution
A system comprising a controller connected to light fixtures with memory chips that store LED data, allowing the processor to determine the intensity of radiant energy for each LED to produce a user-selected color, and employing techniques like constant current and pulse width modulation to prevent color shifts during dimming, along with the use of multiple LEDs with varying wavelengths to create a wide spectrum of colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional LED manufacturing processes are used, then production efficiency is maintained, but manufacturing precision deteriorates due to high variability in LED wavelength and light quality
Solution Approach 1:
The patent measures and stores the actual wavelength and spectral characteristics of each LED during manufacturing or initial setup, before the LED is installed in the fixture. This preliminary characterization data is then used by the controller to calculate appropriate drive currents that will produce the desired spectral output, compensating for manufacturing variations without requiring complex real-time adjustments.
Solution Approach 2:
The system uses measured spectral data from each LED to create a feedback loop where the controller adjusts the drive current to each individual LED based on its specific characteristics. This closed-loop approach ensures that despite manufacturing variations, the combined output of multiple LEDs achieves the target spectral power distribution and color consistency.
2Adaptability or versatility
If multiple LEDs from different manufacturers are used to create a wide spectrum of colors, then adaptability improves, but manufacturing precision deteriorates due to variability in LED characteristics
Solution Approach 1:
The patent treats each LED as having unique local characteristics by measuring and storing individual spectral data for each LED. The controller then applies location-specific drive currents to each LED based on its measured wavelength and efficiency characteristics. This allows the system to use LEDs from multiple manufacturers with different spectral properties while maintaining overall color consistency through individualized control.
Solution Approach 2:
The system changes the electrical parameters (drive current, pulse width modulation duty cycle) for each LED based on its measured spectral characteristics. By adjusting these parameters individually for each LED, the system compensates for manufacturing variations and achieves consistent spectral output across LEDs from different manufacturers with different wavelength characteristics.
3Ease of operation
If conventional dimming techniques are used, then ease of operation improves, but color stability deteriorates due to spectral shifts during dimming
Solution Approach 1:
The system incorporates spectral measurement data to create a feedback mechanism that adjusts drive currents during dimming operations. When the light output level is reduced, the controller references the stored spectral characteristics and modifies the drive current to each LED to compensate for the natural spectral shift that occurs at lower current levels. This maintains color consistency across the dimming range.
Solution Approach 2:
The patent implements dynamic control of LED drive currents based on the desired output level and the measured spectral characteristics of each LED. Rather than using a static dimming approach that applies the same reduction to all LEDs, the system dynamically adjusts individual LED currents to maintain the target spectral power distribution across the entire dimming range, preventing color shifts.
4Manufacturing precision
If individual LED calibration is performed, then manufacturing precision improves, but loss of time increases during setup and calibration
Solution Approach 1:
The patent performs spectral measurements and stores calibration data for each LED during the manufacturing process or initial setup, before the LED is installed in the fixture. This preliminary characterization eliminates the need for time-consuming on-site calibration, as the controller can immediately use the pre-stored data to calculate appropriate drive currents for achieving the desired spectral output.
Solution Approach 2:
The system creates a digital copy or model of each LED's spectral characteristics by measuring and storing its wavelength, spectral power distribution, and efficiency data. This digital twin allows the controller to simulate and calculate the optimal drive currents needed to achieve target spectral outputs without requiring physical trial-and-error calibration, significantly reducing setup time while maintaining precision.
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
Enables uniform color production across different light fixtures, regardless of manufacturer or LED assortment, and allows users to select or create colors locally and remotely, ensuring accurate color representation and consistency.
Implementation Method 1
light emitting diodes (LEDs)
Implementation Method 2
LEDs are subject to manufacturing deviations, which result in each LED possessing slightly different light qualities
Data Source
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AI summary
The present disclosure relates generally to techniques for adjusting a light source to provide radiant energy having a particular spectral characteristic, and more particularly, to a system and method of selectively controlling and calibrating LEDs within a light fixture to produce radiant energy so that the light fixture emits light at a desired color. First, a color is created via a user 1 using a user interface 5 or via a spectrometer or other light measuring source 31. Next, the color is transmitted to controller 3 which controls a light fixture 9 or a mini-fixture 19. The controller 3 then communicates with the memory chip 15 of light fixture 9 or mini-fixture 19 to determine the number of LEDs in the fixture and the wavelength emitted by those LEDs. Processor 7 receives the data 17 from the memory chip 15 and uses an algorithm to determine an amplitudes 13a-13n to be sent to each LED 1 la-1 In in light fixture 9 or mini-fixture 19.