LED Light Guide Homogeneity via Segmented Coupling
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Solution Overview
Problem
Existing LED lighting solutions struggle to produce a light source of any length with minimal local brightness differences along its longitudinal axis, leading to uneven illumination and inefficiencies in energy distribution.
Innovation Solution
The LED lighting device employs multiple light guides with end faces arranged at a specific distance to couple radiation, using means for coupling out radiation on the outer peripheral surface to achieve a homogeneous illumination profile, minimizing brightness differences by optimizing the distance and arrangement of light guides and LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the length of glass rods is increased to produce longer light sources, then the light source length is improved, but the brightness uniformity deteriorates due to unacceptable brightness drop in the middle of the glass rod
Solution Approach 1:
The light guide is divided into multiple sections with light sources positioned at intervals along its length. Instead of using a single long glass rod, the patent segments the light guiding function into multiple segments, each illuminated by its own light source, thereby maintaining brightness uniformity across the entire length while avoiding the brightness drop that occurs in the middle of a single long rod.
Solution Approach 2:
The patent introduces an intermediary light guide structure that couples light from multiple LED sources along its length. This light guide acts as a mediator that distributes light uniformly from multiple sources, preventing the brightness drop that would occur in a single long rod by continuously replenishing light along the propagation path.
2Area of stationary object
If fluorescent tubes are used to illuminate larger areas, then the illumination area is improved, but the mechanical reliability deteriorates due to easy breakability under vibrations and mechanical stresses
Solution Approach 1:
The patent replaces the mechanical fluorescent tube system with an LED-based light guide system. LEDs are solid-state components with no fragile filaments or glass envelopes, making them inherently more resistant to mechanical stress and vibration. The light guide itself is designed to be mechanically robust while maintaining optical functionality, thus substituting the fragile fluorescent tube mechanics with a more reliable solid-state system.
3Illumination intensity
If fluorescent tubes are used for lighting, then the illumination capability is improved, but the device complexity increases due to high ignition voltage requirements and electromagnetic interference
Solution Approach 1:
The patent substitutes the complex fluorescent tube power supply system with a simple LED driver circuit. LEDs operate at low voltages and do not require high-voltage ignition circuits or ballasts. This replacement eliminates the sources of electromagnetic interference associated with fluorescent tube power supplies while maintaining illumination capability, thereby significantly reducing device complexity.
4Reliability
If LEDs are mounted in separate housings on the base profile, then the individual LED protection is improved, but the brightness uniformity deteriorates due to large distances between light guides causing significant brightness drop in spaces between them
Solution Approach 1:
The patent merges multiple light guides into a single integrated structure with continuous light emission along its length. Instead of having separate housed LEDs with gaps between them, the light guide integrates the light transmission function continuously, eliminating the dark spaces between individual LED housings and achieving uniform brightness across the entire lighting 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 results in a lighting device that provides a largely homogeneous lighting profile with minimal perceived brightness differences, allowing for the creation of light sources of any length with improved energy efficiency and reduced mechanical stress, suitable for applications in aircraft and other environments.
Implementation Method 1
The light guides are arranged such that an end face of one light guide and the nearest end face of the other light guide are located at a distance A from each other
Implementation Method 2
the outer surface of the optical fibers contains means for extracting the radiation. During operation, i.e., when current flows through the LED, the radiation emitted by the at least one LED is directed through the end face into the optical fiber and guided by total internal reflection
Data Source
Figure 1~2
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Figure 5
AI summary
LED lighting devices are provided that include two optical waveguides and at least one LED in an intermediate region between end faces of the optical waveguides so that radiation from the LED is coupled into the optical waveguides through the end faces. A de-coupler is on outer circumferential surface regions of each of the two separate optical waveguides. The de-coupler reflects the radiation guided in the optical waveguides so that the radiation passes through the optical waveguides and is coupled out of the optical waveguides laterally. The intermediate region has a length that is selected so that a brightness difference, measured perpendicular to an axis of the optical waveguides in the center of the intermediate region, at a distance of 10 mm perpendicular to the axis of the optical waveguides is at most 25% based on a maximum value of brightness along the axis of the optical waveguides.