Photosensor Light Guide for LED Feedback Control
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Solution Overview
Problem
Existing light sources with feedback control systems for color and luminosity in LED luminaires face issues such as unwanted ambient light interference, insufficient light reaching sensors, and imbalanced LED contributions, leading to unstable color output and efficiency.
Innovation Solution
A light source with a photosensor light guide that captures stray light from LEDs and directs it to photosensors for feedback control, using a substantially planar light guide with in-coupling and out-coupling portions to optimize the sensing of light and reduce ambient light interference, allowing for precise control of LED outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback control system with photosensors is implemented to monitor LED output, then color stability and luminosity control are improved, but unwanted ambient light interferes with sensor accuracy
Solution Approach 1:
A light guide plate is introduced as an intermediary component to channel LED light to the photosensors while blocking ambient light. The light guide plate acts as a mediator that separates the useful light signal from environmental interference, allowing accurate color feedback without ambient light contamination.
Solution Approach 2:
The photosensors are optically coupled to the light guide plate to extract only the LED-generated light for feedback measurement. This extraction principle isolates the measurement signal from ambient light by having sensors read only from the guided LED light path, not from direct environmental exposure.
2Measurement precision
If photosensors are positioned close to LEDs for effective feedback, then light sensing efficiency is improved, but the sensors obscure part of the light source output
Solution Approach 1:
The optical system is segmented into separate functional zones: the light guide plate collects and channels LED light, while photosensors are positioned at a distance to read from the plate's output surface. This segmentation allows sensors to be close enough for efficient coupling while far enough not to block the main light output path.
Solution Approach 2:
The photosensors are positioned in a different spatial dimension relative to the LEDs - coupled to the light guide plate surface rather than directly adjacent to the LED emitters. This dimensional repositioning enables optical coupling without physical obstruction of the light source.
3Adaptability or versatility
If multiple LEDs are used to provide white light or color changing output, then color versatility is improved, but maintaining stable output color becomes more complex
Solution Approach 1:
A single light guide plate serves multiple functions: it guides light from multiple different LED types (red, green, blue, amber), channels their combined output, and delivers the mixed signal to photosensors. This universal light guiding structure simplifies the feedback system compared to having separate sensing paths for each LED type.
Solution Approach 2:
The optical paths from multiple LEDs are merged within the light guide plate, which combines their light and presents a unified signal to the photosensors. This merging approach consolidates what would otherwise require multiple separate sensing systems into a single integrated feedback mechanism.
4Object-affected harmful factors
If a light guide plate is used to direct LED light to photosensors, then ambient light interference is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The light guide plate creates an optical copy or representation of the LED output at its output surface. The photosensors read this optical copy rather than measuring directly at the LED, which provides sufficient measurement accuracy while being more tolerant of manufacturing variations in the coupling interface.
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 solution provides stable color output and luminosity by effectively monitoring and adjusting LED intensities, maintaining desired color quality and rendering efficiency despite temperature changes and aging, while minimizing the impact of ambient light.
Implementation Method 1
a substantially planar light guide comprising one or more in-coupling portions and one or more out-coupling portions
Data Source
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AI summary
The present invention provides a light source comprising one or more light-emitting elements, one or more photosensors and, a photosensor light guide, such as, for example, a substantially planar light guide. The photosensor light guide is generally configured to capture and guide some of the light emitted from the one or more light-emitting elements to one or more photosensors optically coupled thereto, the light sensed thereby being useable as a basis for controlling the respective outputs of the one or more light-emitting elements.