Illumination System Ambient Light Detection Stray Light Rejection
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Solution Overview
Problem
Existing illumination systems face challenges in accurately detecting ambient light intensity and color temperature due to the interference of stray light from the light source, particularly when integrated sensors are used, which limits their ability to adapt to varying ambient conditions effectively.
Innovation Solution
The system employs light sensors with sensitivity peaks set outside the spectrum emitted by the LED module, allowing them to sense primarily ambient light, with multiple sensors covering different wavelength ranges to reduce stray light interference and improve accuracy, and a control circuit that adjusts the LED output based on detected light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light sensor is located in the vicinity of the light source to improve detection of ambient light intensity and CCT, then the detection accuracy is improved, but the effect of stray light from the light source on the light sensor increases
Solution Approach 1:
The patent applies local quality by assigning different spectral sensitivity characteristics to different parts of the sensor system. Specifically, multiple sensors with different spectral responses are used: some sensors are sensitive to wavelengths below 420nm (violet region) and/or above 680nm (red region), while being insensitive to the LED emission spectrum. This localized spectral differentiation allows each sensor to detect specific wavelength ranges, enabling accurate ambient light detection while rejecting stray light from the LED source.
2Device complexity
If integrated light sensors are used to adapt the illumination system to ambient light, then the system integration is improved, but the detection capability is limited by stray light from the light source
Solution Approach 1:
The patent applies segmentation by dividing the detection function into multiple independent sensors, each with specific spectral sensitivity characteristics. Instead of using a single integrated sensor, the system employs multiple sensors with different spectral responses (some sensitive to wavelengths below 420nm and/or above 680nm, others with different characteristics). This segmentation allows the system to detect ambient light parameters accurately while rejecting LED stray light, maintaining system integration without compromising detection capability.
3Measurement precision
If the light sensor senses wavelengths within the LED module spectrum to improve detection sensitivity, then the detection sensitivity is improved, but the ability to distinguish ambient light from LED light is reduced
Solution Approach 1:
The patent applies local quality by creating sensors with specialized spectral sensitivity profiles that match specific wavelength regions. Sensors are designed to be sensitive to wavelengths below 420nm (violet) and/or above 680nm (red), which are outside the main LED emission spectrum. This localized spectral sensitivity allows the sensors to detect ambient light with high sensitivity while automatically discriminating against LED light, as the LED spectrum does not significantly overlap with these wavelength regions.
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 enables the illumination system to reliably adapt to various ambient light situations, such as sunrise, sunset, and different weather conditions, by minimizing the impact of stray light and providing precise control over light output and color temperature, resulting in improved flexibility and accuracy.
Implementation Method 1
the light sensor has its sensitivity peak set to be at a lower wavelength than the spectrum emitted by the LED module, preferably (violet) below 420nm, more preferably below 410nm, and/or that the light sensor has its sensitivity peak set to be at a higher wavelength than the spectrum emitted by the LED module, preferably above red or 680nm
Data Source
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AI summary
The invention proposes an improved illumination system (1). The illumination system (1) comprises: an LED module (2) having at least one LED or OLED; at least one light sensor (3); and a control circuit (4) designed to control the current flowing through the LED module (2), and to be supplied with an individual sensing signal of each of the at least one light sensor (3). The at least one light sensor (3) is designed such that: the light sensor (3) has its sensitivity peak set to be at a lower wavelength than the spectrum emitted by the LED module (2), preferably below 42onm, more preferably below 4ionm, and/or the light sensor (3) has its sensitivity peak set to be at a higher wavelength than the spectrum emitted by the LED module (2), preferably above 68onm. Furthermore, the invention proposes a method for calibrating the illumination system (1). The control circuit (4) is designed to calculate a crosstalk calibration value, by detecting the contribution of a switching on or increasing of the current through the LED module (2) in a non-ambient light state, on the basis of the supplied detection signals.