Light Pipe Extraction Profile for Lateral Illuminance Control
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Solution Overview
Problem
Existing light pipes struggle to provide effective control over lateral illuminance distributions, particularly in side-light mode, leading to inefficient lighting solutions that can increase heat loads and energy consumption in applications like freezer cases.
Innovation Solution
A luminaire design featuring a light pipe with a radial swath of light-extraction means, where the efficiency varies from a first average efficiency point to a second average efficiency point, allowing for improved control of lateral illuminance distributions by optimizing light extraction along the length of the pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is extracted uniformly from the side of the light pipe, then the light extraction is simple to implement, but the lateral illuminance distribution is uneven and cannot be controlled
Solution Approach 1:
The patent applies local quality by varying the extraction efficiency of the light-extraction means at different radial positions. Specifically, the extraction efficiency is set to be lower at radial positions closer to the light pipe center and higher at radial positions farther from the center. This non-uniform local property distribution enables control over lateral illuminance distribution, allowing uniform or customized illumination patterns on target surfaces while maintaining a relatively simple overall structure.
2Illumination intensity
If the light source is placed inside the freezer case to enable side-light illumination, then the lighting function is achieved, but the heat load on the freezer increases
Solution Approach 1:
The patent uses a light pipe as an intermediary to decouple the light source from the target illumination area. The light source is positioned outside the freezer case, and the light pipe serves as a medium to transport the light into the freezer case for side-light extraction. This intermediary approach allows the light source to be thermally isolated from the freezer interior, reducing heat load while maintaining effective illumination.
3Illumination intensity
If constant extraction efficiency is used in the radial swath, then the manufacturing is simple, but the control over lateral illuminance is insufficient
Solution Approach 1:
The patent implements local quality by defining different extraction efficiency zones within the radial swath. The extraction efficiency is set to vary continuously or in steps from the center outward, creating distinct local regions with different optical properties. This approach provides sufficient control over lateral illuminance distribution while maintaining manufacturability through techniques such as variable pigment concentration in coating materials or structured surface features.
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 design reduces heat loads and energy consumption by allowing for more efficient lateral illuminance control, enabling significant energy savings and improved lighting performance in applications such as freezer cases and signage.
Implementation Method 1
a light pipe with a longitudinal center... light propagates to a virtual target area that intersects the propagation plane; the light pipe intervening between the radial swath and the target area
Data Source
AI summary
A luminaire with improved lateral illuminance control comprising a light pipe with a longitudinal center is disclosed. A light-extraction means applied to a radial swath of the light pipe has a longitudinal portion having dimension along its length, centered about a slice on the light pipe longitudinally; said slice being orthogonal to the longitudinal center and located in a propagation plane through which light propagates to a virtual target area intersecting the propagation plane. The light pipe intervenes between the radial swath and the target area. A first average efficiency point of the light-extraction means corresponds to the minimum distance to the target area being at least approximately 20% less than a respective, second average efficiency point corresponding to a respective maximum distance to such area. The light-extraction means efficiency varies from the first average efficiency point to the second average efficiency point though more than one non-zero value.