Light Guide End Surface Adhesive Absorption for Headlight Hotspots
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Solution Overview
Problem
In motor vehicle headlights, elongated light guides often produce hotspots at their ends due to total reflection, leading to uneven light distribution and reduced effective light emission, which is exacerbated by the need to cover these areas to prevent hotspot visibility, thereby shortening the light guide and reducing installation space efficiency.
Innovation Solution
The light guide has a light-transmissive end surface that protrudes into an adhesive bed, allowing light to exit and be absorbed, with the adhesive being light-absorbing to prevent reflection back into the guide, and the end surface geometry optimized for maximum transmittance to minimize hotspots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the light guide is extended beyond the light coupling-out surface, then the effective length and installation space utilization are improved, but hotspots form at the end surface due to total reflection, deteriorating light homogeneity
Solution Approach 1:
The invention converts the harmful total reflection at the light guide end surface into a beneficial effect by applying a light-absorbing adhesive coating. This coating absorbs the reflected light, preventing hotspot formation while maintaining the extended light guide structure for optimal space utilization. The adhesive transforms the harmful reflected light into absorbed energy, eliminating the adverse visual effect.
Solution Approach 2:
The invention applies a light-absorbing adhesive coating specifically at the end surface region of the light guide where hotspots form, rather than modifying the entire light guide structure. This localized treatment addresses the hotspot problem at the critical end area while preserving the light guide's overall functionality and extended length for optimal installation space utilization.
2Object-generated harmful factors
If a screen is added to cover the end area of the light guide, then hotspot visibility is reduced, but the effective length of the light guide is reduced, deteriorating installation space utilization
Solution Approach 1:
The invention changes the optical parameter of the light guide end surface by applying a light-absorbing adhesive coating with different optical properties (high absorption, low reflection) compared to the original transparent or reflective end surface. This parameter change eliminates hotspots without requiring physical coverage, thereby preserving the full effective length of the light guide for optimal installation space utilization.
3Object-generated harmful factors
If a screen is added to cover the end area, then hotspot visibility is reduced, but the light exit surface area is reduced, deteriorating light emission efficiency
Solution Approach 1:
The invention converts the harmful reflected light at the end surface into beneficial absorbed light by applying a light-absorbing adhesive coating. This eliminates hotspots while preserving the full light exit surface area, as the adhesive coating allows light to be absorbed rather than reflected, maintaining optimal light emission efficiency without requiring physical coverage that would reduce the exit surface area.
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 enhances light homogeneity and utilization of installation space by reducing hotspots and maximizing light emission without the need for additional covers, ensuring efficient light distribution and improved appearance.
Implementation Method 1
the adhesive being light-absorbing to prevent reflection back into the guide
Implementation Method 2
light from the at least one light source being able to be coupled into the light guide via a coupling area at a first end area of the at least one light guide, with the at least one light guide having a light decoupling surface and a light deflection surface on a rear side opposite the front side, so that light coupled from the at least one light source into the at least one light guide is deflected at the light deflection surface and emitted from the light-guiding element via the light decoupling surface
Data Source
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AI summary
The invention relates to a lighting unit (100) for a motor vehicle, wherein the lighting unit (100) comprises a housing (10) with a housing opening (11) and a cover plate (12) closing the housing opening (11), wherein an adhesive bed (13) is provided on an edge surrounding the housing opening (11), in which the cover plate (12) is bonded to the housing (10) with an adhesive (14), and wherein at least one elongated light guide (1, 2) is arranged in the housing (10), into which light from at least one light source (3, 4) can be coupled via a coupling area (1a, 2a) at a first end region of the light guide (1, 2), and wherein the at least one light guide (1, 2) has a light-transmitting termination surface in a second end region (21, 22) that delimits the at least one light guide (1, 2). (21a, 22a) and wherein the second end region (21, 22) of the optical fiber (1, 2) projects into the adhesive bed (13),such that the end surface (21a, 22a) at least partially contacts the adhesive (14) located in the adhesive bed (13).