Lighting Device Sensor Placement for Ambient Light Rejection
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Solution Overview
Problem
Existing lighting devices face inefficiencies due to inaccurate sensor readings caused by ambient light interference and sensitivity issues, leading to inaccurate color and intensity measurements of solid state light emitters, particularly in environments with difficult access or high maintenance costs.
Innovation Solution
The design incorporates a lighting device with a reflector and sensor positioned to minimize ambient light interference, where the sensor is placed within a conical region bounded by lines defining an angle of ten degrees or less relative to the light emitter's axis, and is often recessed in the reflector to limit light variation, ensuring that a significant portion of direct light is received while ambient light is minimized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is positioned to receive direct light from the light emitter, then the measurement precision of light intensity is improved, but the sensor becomes more susceptible to ambient light interference
Solution Approach 1:
The sensor is positioned to receive direct light from the light emitter by inverting the conventional approach where sensors typically face away from the light source. This inversion allows the sensor to directly measure the light emitted by the LED, improving measurement precision while the reflector geometry is designed to minimize ambient light interference by directing reflected light away from the sensor's field of view.
Solution Approach 2:
A reflector is introduced as an intermediary element between the light emitter and the sensor. The reflector is positioned to reflect light from the LED toward the sensor, ensuring that the sensor receives sufficient direct light for accurate measurement while the reflector's geometry prevents ambient light from reaching the sensor, thus resolving the contradiction between measurement accuracy and ambient light susceptibility.
2Illumination intensity
If multiple solid state light emitters of different colors are used to produce white light, then the color reproduction quality is improved, but the complexity of maintaining consistent color output increases
Solution Approach 1:
The sensor provides feedback on the actual color output by measuring the light emitted by the solid state light emitters. This feedback is used to detect deviations from the desired color range, and the controller adjusts the current supplied to each emitter accordingly, maintaining consistent color reproduction despite variations in emitter intensity or ambient conditions.
Solution Approach 2:
The system dynamically changes the electrical parameters (current) supplied to each solid state light emitter based on real-time sensor measurements. By adjusting the current to individual emitters of different colors, the system maintains the desired color temperature and reproduction quality, resolving the complexity of coordinating multiple color sources.
3Use of energy by moving object
If solid state light emitters are used to replace traditional lighting devices, then the energy efficiency is improved, but the cost of periodic replacement and maintenance increases for difficult-to-access installations
Solution Approach 1:
The lighting device incorporates a sensor and controller that automatically monitor and adjust the operation of solid state light emitters. This self-service capability detects when emitters are approaching end-of-life or when color output deviates from specifications, and automatically compensates or alerts for replacement, reducing the need for frequent manual inspections and maintenance trips to difficult-to-access locations.
Solution Approach 2:
The system replaces manual mechanical inspection and adjustment processes with automated optical sensing and electronic control. The sensor continuously monitors emitter performance, and the controller automatically adjusts operation, eliminating the need for periodic manual maintenance and replacement, thus resolving the accessibility issue for hard-to-reach installations.
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 enhances the accuracy of light measurements by reducing ambient light interference, allowing for precise adjustment of current to maintain desired color ranges and extending the lifespan of solid state light emitters, thereby improving energy efficiency and reducing maintenance needs.
Implementation Method 1
a first sensor in a conical region bounded by lines that each define an angle of ten degrees or less relative to an axis of direct light emitted by said first light emitter... said first sensor receiving direct light from said first light emitter
Implementation Method 2
a first reflector... comprising at least a first opening, said first sensor opposite said first opening with respect to said first light emitter, such that a portion of light emitted by said first light emitter passes through said first opening to said first sensor
Data Source
AI summary
There is provided a lighting device, comprising at least one light emitter, at least one reflector and at least one sensor. The sensor is positioned within a region which receives direct light from the light emitter when the light emitter is emitting light. In some embodiments, the light emitter comprises one or more light emitting diode. In some embodiments, the sensor is positioned between the light emitter and a power supply. In some embodiments, the reflector comprises at least one opening, and light emitted by the light emitter passes through the opening to the sensor. In some embodiments, the sensor is sensitive to only some wavelengths of visible light. Some embodiments are back-reflecting lamps, and some are forward-reflecting lamps.