Automotive Lightguide Complex Prism Homogeneity
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Solution Overview
Problem
The use of optical guides with two light sources in automotive signaling and lighting devices, such as vehicle headlamps, results in discontinuity in light beam homogeneity, especially when the guide is strongly curved and one source is angularly offset from the optical axis, leading to uneven light emission and appearance.
Innovation Solution
A linear optical guide with complex prisms that have a first side for reflecting one luminous flux and a second side with two surfaces forming an obtuse re-entrant angle to deflect rays back into the guide, ensuring uniform light distribution and eliminating discontinuities, even when light sources are offset from the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If two light sources are used on the same waveguide to illuminate long or highly curved guides, then the light emission coverage is improved, but discontinuity and non-uniformity appear at the junction between waveguide sections
Solution Approach 1:
The patent applies local quality by differentiating the functions of different prism regions along the waveguide. Prisms in the first region reflect rays from the first light source, while prisms in the second region reflect rays from the second light source. This localized functional differentiation allows each region to optimize for its specific light source while maintaining overall beam homogeneity across the entire waveguide output.
2Adaptability or versatility
If the waveguide is highly curved or light sources are angularly offset from the optical axis, then the light distribution flexibility is improved, but the discontinuity at junctions is exacerbated
Solution Approach 1:
The patent employs parameter changes by varying the angular orientation of prisms along the waveguide length. Prisms are configured with different reflection angles to accommodate highly curved waveguide paths and angularly offset light sources. This gradual parameter variation ensures continuous light reflection and maintains beam homogeneity even when the waveguide geometry or light source positions change significantly.
3Ease of manufacture
If simple triangular prisms are used in the waveguide, then the manufacturing complexity is reduced, but the brightness uniformity on the exit face is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the waveguide into multiple sections with different prism configurations. The waveguide is segmented into a first region with prisms optimized for the first light source and a second region with prisms optimized for the second light source. This segmentation allows each region to contribute uniformly to the overall brightness distribution, achieving homogeneous illumination that simple uniform prisms cannot provide.
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 provides continuous and uniform light emission and extinction appearance, improving the homogeneity of the illuminated aspect by reducing the contrast between prism lines and increasing the flux recovery, allowing for a more efficient light distribution around the desired optical axis.
Implementation Method 1
light rays to propagate within the waveguide, towards the end of the waveguide longitudinally opposite the source, by internal reflection on the waveguide's surfaces
Implementation Method 2
a prismatic reflecting surface reflects some rays so that they propagate within the waveguide, while reflecting other rays at an angle that causes them to exit the waveguide
Data Source
Figure 1~3
Figure 4~6
AI summary
The guide has a face opposed to a light beam face exit and including prisms following one another according to a longitudinal direction (7) of the guide. The face is arranged to reflect rays of luminous flows towards the exit face. One of the prisms is a complex prism (11), which includes a side (12) configured to reflect rays of one of the flows towards the exit face, and another side (13) including two sections (14, 15). One of the sections reflects rays towards the exit face, and another section deviates the rays towards interior of the guide.