Light-Guide Decoupling for Multi-Directional Vehicle Lighting
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Solution Overview
Problem
Conventional light-guiding optical systems for motor vehicles struggle to efficiently distribute light to multiple directions, such as up to 90°, while maintaining high light intensity and homogeneity, especially in complex 3D shapes like modern headlights and lamps that require various light functions.
Innovation Solution
A light-guiding optical system with a light guide featuring decoupling surfaces and reflective elements that direct light rays to specific output directions, including a combination of reflective surfaces oriented at obtuse angles and lengths tailored for optimal light distribution, ensuring light rays exit the guide without total reflection, thereby achieving efficient light distribution across different functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional light guides use total internal reflection to guide light, then light can be transmitted along the optical axis with minimal loss, but light cannot be efficiently distributed to multiple directions (up to 90°) while maintaining high intensity and homogeneity
Solution Approach 1:
The light guide is segmented into multiple functional zones along its longitudinal axis, with each zone containing decoupling elements oriented at specific angles to direct light in different directions. This segmentation allows the single light guide to fulfill multiple light functions (tail light, side clearance light, etc.) while maintaining homogeneous light distribution in each direction through optimized decoupling element geometry and spacing.
2Adaptability or versatility
If decoupling elements are added to the light guide to distribute light to multiple directions, then light can be directed to fulfill various light functions, but light loss increases and homogeneity decreases
Solution Approach 1:
Different sections of the light guide are equipped with decoupling elements having locally optimized properties (angle, depth, spacing) matched to the specific light function required at that position. This local quality optimization ensures that each decoupling event extracts only the necessary amount of light in the required direction, minimizing energy loss while achieving the desired light distribution pattern for tail lights, side clearance lights, and other functions.
3Ease of manufacture
If the light guide uses a simple cylindrical shape, then manufacturing is easier, but light distribution to multiple directions with high homogeneity cannot be achieved
Solution Approach 1:
The invention transitions from simple cylindrical light guides to prismatic light guides with polygonal cross-sections (triangle, quadrangle, pentagon, hexagon). This dimensional change in the cross-sectional geometry enables precise control over light decoupling angles and directions through the prism faces, achieving homogeneous light distribution to multiple directions while maintaining manufacturing feasibility through standard molding techniques for the polyhedral shapes.
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 system effectively directs light to multiple directions with high efficiency and homogeneity, adapting to the mechanical and optical design of the lighting device, ensuring clear visibility and fulfilling various photometric requirements, including tail lights and side clearance lights.
Implementation Method 1
The conduction of light in light guides is based on the principle of total light reflection. Light bound to a light guide from a light source, most frequently a LED (light-emitting diode) propagates along the optical axis through the light guide, using total reflection from the cylindrical walls of the light guide.
Implementation Method 2
Total reflection occurs at the interface of two environments having a different refractive index. If a light ray spreads at an angle Φi that is bigger than the critical angle Φc from an optically denser environment (i.e. environment with a higher refractive index value to an optically sparser environment, i.e. having a lower refractive index value), total reflection occurs at the interface
Data Source
AI summary
The light-guiding optical system comprises at least one light source (2) and a light guide (1) for coupling and guiding light rays (10) emitted by a light source (2). Furthermore, the light guide (1) may comprise a decoupling surface (4) on its rear side (13) and an output surface (3) for the exit of light rays (10) decoupled by the decoupling surface (4) on an opposite front side (14). The decoupling surface (4) comprises: (i) first decoupling elements (5) configured to decouple light rays (10) falling onto the first decoupling elements (5) out of the light guide (1) approximately in a pre-determined first output direction (p) to fulfill a first light function, and (ii) a second decoupling element (6) configured to uncouple light rays (10) falling onto the second decoupling elements (6) out of the light guide (1) approximately in a pre-determined second output direction (d), which is deflected from the first output direction (p), to fulfill the second light function.