Asymmetric Light Extracting Structures for Uniform Illumination
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Solution Overview
Problem
Lightguides used in linear lighting devices face challenges with light power and color uniformity due to absorption losses, leading to reduced efficiency and non-uniform illumination.
Innovation Solution
Incorporating a plurality of discrete light extracting structures with specific angles and configurations, such as notches and protrusions, along the lightguide to reflect light towards the center, optimizing light extraction and reducing absorption, thereby enhancing light uniformity and system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If light propagates through a lossy lightguide, then light can be transported over distance, but light power and color uniformity are reduced due to absorption
Solution Approach 1:
The lightguide is divided into multiple sections with discrete light extracting structures at different positions. Each structure extracts light locally, segmenting the overall light extraction process to compensate for absorption losses along the length of the lightguide
Solution Approach 2:
Different light extracting structures are positioned at different locations along the lightguide with specific angular orientations tailored to each position. This local customization optimizes light extraction efficiency at each segment to maintain uniformity despite varying absorption characteristics
2Length of stationary object
If light propagates through a lossy lightguide, then light can be transported over distance, but color uniformity is reduced
Solution Approach 1:
The light extraction is segmented into multiple discrete structures positioned along the lightguide. This segmentation allows independent optimization of each extraction point to maintain consistent color output across the entire length despite absorption variations
Solution Approach 2:
The angular parameters of the light extracting structures are varied along the length of the lightguide. By changing the orientation angles of different structures, the patent compensates for absorption effects and maintains uniform color characteristics across the full propagation distance
3Illumination intensity
If conventional light extracting structures are used, then light extraction is achieved, but absorption losses reduce system efficiency
Solution Approach 1:
Light is extracted at multiple predetermined positions along the lightguide before significant absorption losses can occur. The discrete light extracting structures are positioned to capture light early in its propagation path, preventing energy loss
Solution Approach 2:
The angular orientation of light extracting structures is optimized to specific values (e.g., 45 degrees, 60 degrees) to maximize extraction efficiency. By carefully selecting these angular parameters, the system minimizes absorption losses while maintaining high light extraction performance
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
The solution significantly mitigates absorption losses, achieves improved illumination uniformity, and increases system efficiency by directing light towards the target plane with reduced color shift, as demonstrated by simulations and experimental results.
Implementation Method 1
the first surface of each light extracting structure may be adapted to extract light propagating in the first direction along the optical axis from the second side of the lightguide by reflecting the propagating light toward the second side primarily by total internal reflection
Data Source
AI summary
A lightguide defines an optical axis and has an optical absorption coefficient of at least 0.02 cm−1 at a wavelength of 500 nm. The light guide includes a plurality of discrete light extracting structures, each with a first surface configured to extract light propagating in a first direction along the light guide, a second surface configured to extract light propagating in a second direction along the light guide, and a light extraction efficiency of less than 2%. The first surface and the second surface in each of the light extracting structures making an angle with each other larger than 90 degrees; the angle between the first and second surfaces of at least one of the light extracting structures being different from the angle between the first and second surfaces of at least another one of the light extracting structures.