Light Guide Decoupling Portion for Homogeneous Vehicle Lighting
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Solution Overview
Problem
Light guides used in motor vehicle lighting and signaling often suffer from inhomogeneous lighting due to imperfections caused by assembly and manufacturing constraints, leading to areas of over-intensity that are both photometrically and aesthetically undesirable.
Innovation Solution
A light guide with intentionally formed irregularities, specifically decoupling portions that refract light rays instead of reflecting them, to prevent untimely decoupling and improve homogeneity, along with a variable section that facilitates easier demolding and fixing, and a cover to mask decoupled rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light guide is designed with a variable cross-section to facilitate assembly and demolding, then ease of manufacture is improved, but inhomogeneous lighting is generated due to premature ray decoupling
Solution Approach 1:
The patent applies local quality by creating a specific decoupling portion with a particular geometric configuration (smaller cross-section) at a localized position within the light guide, rather than making the entire light guide variable cross-section. This localized modification allows premature ray decoupling to be controlled and directed toward the mask, while maintaining uniform lighting in the main propagation path. The decoupling portion has specific dimensional characteristics (cross-sectional area at least twice smaller than the light guide cross-section) that enable it to selectively intercept and redirect stray rays.
2Illumination intensity
If reflective facets are used to decouple rays for lighting function, then lighting effectiveness is improved, but areas of over-intensity are created leading to inhomogeneous lighting
Solution Approach 1:
The patent introduces a mask as an intermediary element positioned between the light guide and the external environment. This mask selectively blocks certain light paths and intercepts stray rays that would otherwise create areas of over-intensity. The mask works in conjunction with the decoupling portion to redirect and control the distribution of light rays, ensuring homogeneous lighting across the entire light guide output surface while maintaining effective illumination.
3Manufacturing precision
If a cover is added to mask decoupled rays, then lighting homogeneity is improved, but device complexity increases
Solution Approach 1:
The patent merges the mask function with the existing light guide structure by integrating the mask directly into the light guide assembly. The mask is positioned at the end of the light guide where stray rays exit, combining the light guiding function with the ray masking function in a unified structure. This integration approach minimizes the increase in device complexity while achieving homogeneous lighting, as the mask becomes an inherent part of the light guide system rather than a separate complex assembly.
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 more uniform lighting distribution by controlling the exit of light rays, eliminating inhomogeneities and enhancing the aesthetic and photometric quality of the lighting.
Implementation Method 1
The surface of the waveguide forms a diopter between the waveguide material, which has a given refractive index (typically around 1.6 for polycarbonate), and the surrounding air, which has a different refractive index (very close to 1). This difference in refractive index between two adjacent media results in a critical angle of incidence beyond which refraction is impossible and total internal reflection occurs.
Implementation Method 2
This difference in refractive index between two adjacent media results in a critical angle of incidence beyond which refraction is impossible and total internal reflection occurs. In the case of a polycarbonate medium surrounded by air, this critical angle is approximately 39° (according to Snell's law).
Data Source
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AI summary
The guide (1004) has an external surface forming a guiding diopter, where the guide is provided for guiding light rays by reflection on the guiding diopter. A decoupling portion (1030) is arranged with a refraction decoupling diopter (1034) so as to refract the light rays to decouple the rays from the guide, and to transmit the rays out of the guide through the refraction decoupling diopter. The decoupling portion is arranged on a section of variable cross-section (1024) that is adjacent to an end of the guide. The section of the variable cross-section of the guide comprises a fastening unit.