Headlamp Light Guide End Surface for Hotspot-Free Light Emission
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Solution Overview
Problem
Existing lighting devices in motor vehicle headlights using elongated optical fibers suffer from hotspots at the end section due to reflections, which disrupt the uniformity of light emission and reduce the effective length and light emission area, necessitating space-consuming solutions like apertures that compromise installation space and light output.
Innovation Solution
The end surface of the optical fiber is shaped to follow a virtual base surface with targeted deviations through optical surface segments, distributing light reflections to avoid hotspots and reduce luminance differences, allowing for controlled light exit and adaptation to headlight housing shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat termination surface is used at the end of the optical fiber, then the structure is simple and easy to manufacture, but hotspots are formed due to concentrated light reflections, disrupting uniformity
Solution Approach 1:
The termination surface is segmented into multiple inclined surface segments instead of being flat. Each segment is angled to reflect light away from the optical axis, distributing the reflected light more evenly and preventing hotspot formation while maintaining manufacturability through standardized segment geometries.
Solution Approach 2:
The termination surface uses asymmetric inclination angles for different segments rather than a symmetric flat surface. This asymmetric design directs reflected light at various angles to achieve uniform distribution along the optical fiber, eliminating the concentrated reflections that cause hotspots.
2Area of stationary object
If the end section of the optical fiber is visible, then the effective length and light emission area are maximized, but hotspots are visible which negatively affect the appearance
Solution Approach 1:
Different segments of the termination surface are given different local qualities through varying inclination angles. This allows each segment to control light reflection locally, directing it away from the optical axis to eliminate hotspots while preserving the overall light emission area and effective length of the optical fiber.
3Illumination intensity
If apertures are used to cover the end section and hide hotspots, then the appearance uniformity is improved, but the effective length and light emission area are reduced, consuming installation space
Solution Approach 1:
Instead of hiding the hotspots with apertures, the invention converts the harmful concentrated reflections into beneficial distributed light patterns by using inclined surface segments. The reflection that previously created hotspots is now directed at angles that distribute light evenly, eliminating the need for apertures and preserving the full effective length and light emission 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
The solution effectively reduces or eliminates hotspots, optimizing light distribution and maintaining uniformity while maximizing the effective length and light emission area without requiring additional space, thus enhancing the appearance and functionality of the lighting device.
Implementation Method 1
Light coupled into the optical fiber propagates longitudinally along the fiber due to total internal reflection
Implementation Method 2
a light deflection surface is provided on its rear side. This surface is designed such that, in a known manner, light is deflected to the light output surface and strikes it at an angle that allows the light to exit the optical fiber
Data Source
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AI summary
The invention relates to a lighting device (100) for a motor vehicle, comprising an elongated light guide (1) and at least one light source (2) associated with the light guide (1). The light guide (1) has a termination surface (21) in an end section (20) that limits the light guide (1), wherein the shape of the termination surface (21) follows the shape of a virtual base surface (30), wherein at least in areas of the virtual base surface (30) targeted deviations from the shape of the virtual base surface (30) are provided by providing several optical surface segments (40), wherein the termination surface (21) is formed by the optical surface segments (40) in the areas where a targeted deviation exists and corresponds to the virtual base surface (30) in the areas without deviation, and wherein the optical surface segments (40) deviate from the virtual base surface (30) such that from a,more light can exit the optical guide (1) from several or preferably each optical surface segment (40) than from a corresponding virtual base shape surface segment (30a), and/or reflects one, several, or preferably each optical surface segment (40) of the optical surface (1) as it propagates in the optical guide (1) to the termination surface (21) in such a way that the amount of light exiting the light coupling surface (11) per unit area in an end section (20) of the optical guide (1) is less than would be the case if reflected at the virtual base surface (30).