Automotive Light Guide Plate Transversal Groove Uniformity
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Solution Overview
Problem
Automotive rear lights with ribbon-like transparent or semi-transparent portions face issues with non-uniform light intensity due to the placement of LED diodes, leading to uneven backlighting and a less desirable appearance.
Innovation Solution
The automotive lighting unit incorporates a light-guide plate with a transversal groove and stepped profile, allowing for total internal reflection to distribute light uniformly along the front sidewall, while minimizing the unit's dimensions by optimizing the placement of LED diodes and light sources to parallel the main optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If LED diodes are positioned to strike against the end segment of the rear sidewall of the light-guide plate, then the depth of the lighting unit is reduced, but light intensity uniformity deteriorates due to direct light reaching the front sidewall
Solution Approach 1:
The patent introduces a reflective layer as an intermediary element between the LED diodes and the light-guide plate. This reflective layer redirects the light that would otherwise directly reach the front sidewall, ensuring uniform light distribution while maintaining the reduced depth configuration. The reflective layer acts as a mediator that transforms the optical path without requiring increased depth.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the light-guide plate. Specifically, the front sidewall region is designed with enhanced light extraction features or different refractive properties compared to other regions, allowing it to uniformly distribute light even when receiving light from a compact LED arrangement. This local differentiation enables uniform illumination without increasing overall depth.
2Illumination intensity
If the light-guide plate is made with significant width to ensure uniform light distribution, then light intensity uniformity is improved, but the depth of the lighting unit increases
Solution Approach 1:
The patent modifies optical parameters such as refractive index, absorption coefficients, or surface roughness at specific locations within the light-guide plate. By changing these optical parameters locally, the plate can achieve uniform light distribution with a more compact width, thereby reducing the overall depth of the lighting unit while maintaining illumination quality.
3Device complexity
If a small group of LED diodes is used to reduce component count, then device complexity is reduced, but light intensity uniformity deteriorates due to direct light reaching the front sidewall
Solution Approach 1:
The reflective layer serves as a mediator that enables a small group of LED diodes to achieve uniform light distribution. By redirecting light that would otherwise create hot spots, the reflective layer allows fewer LED diodes to effectively illuminate the entire front sidewall uniformly, thus reducing device complexity without sacrificing illumination quality.
Solution Approach 2:
The patent replaces a mechanical solution (using more LED diodes to cover the entire area) with an optical solution (using a reflective layer to redirect light). This substitution reduces the number of physical components while achieving the same uniform illumination effect through optical manipulation.
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 configuration ensures uniform light intensity along the front sidewall, enhancing the quality of backlighting and reducing the overall size of the lighting unit, addressing the issue of non-uniformity and depth constraints.
Implementation Method 1
The light produced by this small group of LED diodes reaches the front sidewall of the light-guide plate following an optical path that has a length that is substantially equal to the one of the optical path followed by the light emitted by the LED diodes striking against the rest of the rear sidewall of the light-guide plate
Data Source
AI summary
Automotive lighting unit comprising a first lighting assembly able to backlight a transparent or semi-transparent portion of the front half-shell; the lighting assembly comprising: at least one light-guide plate made of photoconductive material, which is arranged inside the rear casing with a front sidewall of the plate facing the transparent or semi-transparent portion, and with a rear sidewall of the plate facing the rear casing; a first oblong light source which is located inside the rear casing at a first segment of the rear sidewall, and is capable of directing the light produced inside the light-guide plate so that the light travels inside the body of the light-guide plate towards the front sidewall; and a second light source which is located inside the rear casing at a second segment of the rear sidewall complementary to the first segment, and is capable of directing the light produced inside the light-guide plate, so that this light travels inside the body of the light-guide plate towards a first lateral sidewall of the light-guide plate connecting the second segment of the rear sidewall of the light-guide plate to the front sidewall of the same light-guide plate. The light-guide plate is provided with a transversal groove that extends along one of the two faces of the light-guide plate, from the front sidewall of the light-guide plate towards the rear sidewall of the light-guide plate, so as to be interposed between the first lateral sidewall of the plate and the front sidewall of the plate, and is crossed by the light reflected by the first lateral sidewall of the light-guide plate towards the front sidewall of the light-guide plate.