LED Lighting Device Color Drift Compensation via Feedback Control
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Solution Overview
Problem
Conventional lighting devices struggle to maintain a consistent color emission over time due to differences in ageing behavior and temperature dependence among various classes of light-emitting diodes, leading to fluctuations in light color and color temperature.
Innovation Solution
The lighting device incorporates a carrier with mounted light-emitting diodes of different colors and a color sensor that detects light intensity, along with a light-measuring area to reflect and scatter light, allowing for measurement values to regulate the diodes to maintain a constant color locus and temperature, using a drive apparatus to adjust operating conditions based on these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple classes of light-emitting diodes with different colors are used, then the lighting device can emit white mixed light, but the color consistency deteriorates over time due to different ageing behaviors and temperature dependence
Solution Approach 1:
The patent employs color sensors to detect the actual color output of the LED mixture and feeds this information back to a control unit. The control unit adjusts the driving currents of individual LED classes based on this feedback to compensate for color drift caused by ageing and temperature variations, thereby maintaining consistent color output over time
Solution Approach 2:
The system dynamically changes the operating parameters (driving currents) of different LED classes based on detected temperature and color measurements. By adjusting these parameters in real-time, the system compensates for the inherent instability of multiple LED classes and maintains consistent color mixing ratios
2Stability of the object's composition
If color sensors and control systems are added to maintain color consistency, then color stability improves, but device complexity increases
Solution Approach 1:
The control unit serves multiple functions: it processes temperature sensor data, receives color sensor measurements, calculates appropriate current adjustments, and controls multiple LED classes. This multi-functionality reduces the need for separate dedicated components for each control task, thereby limiting the increase in overall system complexity
3Measurement precision
If light-measuring areas are added to reflect and scatter light for measurement, then measurement accuracy improves, but manufacturing complexity increases
Solution Approach 1:
Instead of making the entire housing complex, the patent introduces light-measuring areas with specific optical properties (reflective and scattering characteristics) only at the locations where light measurement is required. These localized treatments with specialized optical properties allow accurate color detection without requiring complex manufacturing across the entire device
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 configuration ensures that the lighting device emits light with a consistent color and color temperature over a long period, reducing fluctuations by ±5% or less, thereby maintaining a stable light output.
Implementation Method 1
at least one color sensor which detects the light from at least one of the multiplicity of light-emitting diodes during operation
Implementation Method 2
at least one light-measuring area which is illuminated by the light from at least one of the multiplicity of light-emitting diodes and reflects and/or scatters at least part of said light
Implementation Method 3
at least one light-measuring area which is illuminated by the light from at least one of the multiplicity of light-emitting diodes and reflects and/or scatters at least part of said light
Implementation Method 4
a multiplicity of light-emitting diodes, wherein at least two of the light-emitting diodes are suitable for emitting light of mutually different colors during operation
Data Source
AI summary
A lighting device has a carrier with a mounting face. A number of light-emitting diodes include at least two of the light-emitting diodes suitable for emitting light of different colors during operation. At least one color sensor, during operation, detects the light of at least one of the light-emitting diodes. At least one light-measuring face is illuminated by light of at least one of the light-emitting diodes and reflects and/or scatters at least a portion of this light. The light-emitting diodes and the at least one color sensor are arranged on the mounting surface, the at least one light-measuring face is arranged at a distance from the carrier, and the at least one color sensor; detects for the most part light reflected by the at least one light-measuring face from at least one of the multiplicity of light-emitting diodes.