Light Guide with Dual Rows of Inclined Reflecting Facets
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Solution Overview
Problem
Existing light guides for motor vehicle lighting and signaling devices face challenges in producing a homogeneous light beam, with previous solutions either resulting in irregular images or non-homogeneous beams for viewing angles off the main axis due to variations in facet pitch and height or width along the guide.
Innovation Solution
A light guide with a transparent body featuring a diopter surface and two rows of inclined reflecting facets, where the first row has larger facets that increase in width and the second row has smaller facets, both with connecting facets forming prismatic volumes, allowing for efficient light exit and beam homogeneity along and transverse to the guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pitch and/or height of prismatic facets are varied along the guide to compensate for progressive light loss, then light homogeneity along the guide is improved, but image irregularity increases
Solution Approach 1:
The patent applies local quality by varying the pitch and/or height of prismatic facets at different locations along the light guide. Specifically, the pitch between adjacent facets or the height of facets is modified in the direction of light propagation to compensate for progressive light loss, while maintaining optical functionality. This localized variation achieves homogeneous light distribution without requiring uniform facet dimensions throughout the guide.
2Illumination intensity
If the width of prismatic facets is increased progressively along the guide to compensate for light loss, then light homogeneity is improved, but beam homogeneity for off-axis viewing angles deteriorates
Solution Approach 1:
The patent applies local quality by progressively increasing the width ofprismatic facets along the light guide in the direction of light propagation. This gradual width increase compensates for progressive light loss and achieves homogeneous light distribution along the guide while maintaining beam homogeneity for off-axis viewing angles.
3Illumination intensity
If multiple rows of reflecting facets with different characteristics are used, then beam homogeneity is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the light guide into multiple rows of reflecting facets, where each row contains facets with specific characteristics (different pitches, heights, or widths). This segmentation allows different rows to contribute differently to light extraction, achieving homogeneous beam distribution while managing structural complexity through organized row configurations.
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 generates a highly homogeneous light beam along the principal direction and transversely, effectively compensating for progressive light loss and improving beam homogeneity across various viewing angles.
Implementation Method 1
reflecting facets having a prismatic profile so as to deviate light rays passing through the guide by successive reflection at the diopter. This deviation enables the rays in question to encounter the diopter with an angle of incidence less than the total reflection limit angle and therefore to exit the body of the guide.
Data Source
AI summary
A light guide including a transparent body which is generally elongated in a principal direction with an outer facet forming a diopter with the environment of the body, a first row of inclined facets adapted to reflect the rays in order for them to exit, and at least one second row of reflecting facets of smaller size than the corresponding reflecting facets of the first row. The light reflected by the second row or rows is added to the light beam coming from the first row. The widths of the first row and the second rows can respectively and progressively increase and decrease from the light source so as to compensate the progressive losses of light traveling in the light guide.