Light Guide Panel Assemblies with Homogenizing Reflector
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Solution Overview
Problem
Conventional light emitting panel assemblies face challenges in achieving even illuminance and reducing glare, particularly in vertically oriented configurations, where high luminance at low vertical angles causes visual discomfort, and in horizontally oriented configurations, where glare is mitigated by baffling, while also dealing with undesirable visible lines of light emission.
Innovation Solution
The design incorporates vertically oriented light guides with decreasing width, angled extraction elements, and reflective surfaces to balance light extraction and distribution, using upper and side guide reflectors to homogenize light and minimize glare, ensuring even illuminance and reducing visible light lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If light emitting panel assemblies are vertically oriented to reduce glare at high vertical angles, then projected area increases at higher vertical angles avoiding glare, but small projected area at low vertical angles results in high luminance causing visual discomfort
Solution Approach 1:
The light guide is designed with non-uniform extraction characteristics along its length, with extraction elements having varying depths and densities. The lower portion has deeper and more densely spaced extraction elements to reduce luminance, while the upper portion has shallower and more sparsely spaced elements to maintain brightness, creating locally optimized light distribution properties.
Solution Approach 2:
The patent employs dynamic light redistribution through reflective surfaces and multiple internal reflections within the light guide. Light from LED modules is dynamically redirected through total internal reflection and specular reflection to achieve uniform luminance distribution across the vertical surface, adapting the light path based on geometric optics principles.
2Productivity
If conventional light guides are used with uninterrupted linear light paths, then light transmission is efficient, but visible lines of light (headlamping) appear from extraction elements
Solution Approach 1:
The light guide surface is segmented into multiple extraction elements distributed along the light guide length. Each extraction element acts as an independent light extraction zone, breaking the continuous light path into discrete segments that prevent the formation of visible headlamp lines while maintaining overall light transmission efficiency.
Solution Approach 2:
Extraction elements are designed with varying local properties including different depths, widths, and spacing intervals along the light guide. This local variation in extraction characteristics ensures that light is extracted uniformly across the surface, preventing concentration of light into visible lines while preserving efficient light transmission through the guide.
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 achieves a desirable batwing distribution with even illuminance and reduced glare, enhancing visual comfort by minimizing high luminance at low angles and eliminating undesirable light lines, while allowing for cost-effective LED spacing and improved optical control.
Implementation Method 1
Light travels through the light guide by way of total internal reflection until it is extracted
Implementation Method 2
when the light is extracted by extraction elements the light can appear to the viewer as undesirable visible lines of light
Data Source
Figure 1
Figure 2A~2D
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AI summary
A light emitting panel assembly is provided. The light emitting panel assembly includes: a housing; a light guide within the housing, the light guide having a first major surface with a plurality of extraction elements, a second major surface, a lower surface, an upper surface, a light source adjacent to the lower surface of the light guide; and an upper guide reflector having a diffuse reflective surface adjacent to and facing the upper surface of the light guide, whereby light from the light source traveling through the light guide toward the upper guide reflector spreads within the light guide, and whereby the upper guide reflector homogenizes the light before the light is redirected to the light guide. A luminaire comprising such a light emitting panel assembly is also provided.