Vehicle Lighting Device Flat Light Guide Homogeneous Scatter
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Solution Overview
Problem
Existing vehicle lighting devices with flat light guides struggle to achieve a homogenous light distribution over a large scattering angle, particularly due to limited scatter effects caused by comparatively flat scattering elements.
Innovation Solution
The light output coupling surface features alternately arranged protrusions and depressions, with protrusions having lateral slopes and tip surfaces that refract and reflect light beams to generate a central and lateral region of light distribution, allowing for a wide and homogenous light scatter without interfering stripes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If comparatively flat scattering elements are used on the light output coupling surface, then the device structure remains simple, but the scatter effect is limited and cannot achieve large scattering angles
Solution Approach 1:
The light output coupling surface is segmented into multiple protrusions and depressions arranged in alternating patterns. Each protrusion contains lateral slopes and a tip surface, creating distinct light deflection zones. This segmentation allows different regions to control light in specific directions, achieving large scattering angles through coordinated action of multiple elements rather than relying on a single flat scattering surface.
Solution Approach 2:
The protrusions and depressions introduce curved surfaces to the otherwise flat light guide output. The lateral slopes of protrusions and the curved tip surfaces create varying normal vectors that deflect light at different angles. This curvature transformation converts the limited scatter of flat surfaces into a wide angular distribution, with tip surfaces generating central light distribution and lateral slopes generating lateral light distribution.
2Illumination intensity
If multiple scattering elements are added to achieve large scatter angle, then scattering performance improves, but interfering stripes appear in the light distribution
Solution Approach 1:
Different regions of the light output coupling surface are assigned different functions: tip surfaces of protrusions are optimized for generating central light distribution, while lateral slopes are optimized for generating lateral light distribution. The depressions between protrusions further modulate the light pattern. This local quality differentiation ensures that each region contributes constructively to the overall homogeneous distribution, preventing the formation of interfering stripes that would result from uniform scattering elements.
3Illumination intensity
If the light output coupling surface is kept flat, then manufacturing is simpler, but homogenous light distribution over large angles cannot be achieved
Solution Approach 1:
The invention introduces protrusions and depressions with curved tip surfaces and lateral slopes to the light output coupling surface. These curved features refract and reflect light at varying angles, creating homogeneous light distribution across a wide angular range. The alternating pattern of protrusions and depressions ensures uniform light extraction throughout the surface, achieving homogeneity that flat surfaces cannot provide.
Solution Approach 2:
The light output coupling surface transitions from a two-dimensional flat plane to a three-dimensional structured surface with protrusions and depressions. This dimensional addition creates multiple light interaction paths through refraction at tip surfaces and total internal reflection at lateral slopes. The third dimension (surface relief) enables control over light distribution homogeneity and scattering angle simultaneously, overcoming the limitations of flat surfaces.
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 design enables a homogenous light distribution with a large horizontal scatter angle, effectively utilizing the entire luminous flux and providing a wide light distribution without stripes, suitable for various lighting functions in vehicles.
Implementation Method 1
a partial light beam of the entering light striking the collection surface is reflected in total towards the light output coupling surface
Implementation Method 2
a partial light beam totally reflected from the collection surface and/or a flat side and an additional partial light beam originating directly from the light input coupling surface are refracted at the tip surface to generate a central region of light distribution
Implementation Method 3
an additional partial light beam of the input light striking the lateral slope is totally reflected towards the tip surface, in order to exit at the tip surface under a comparatively large angle to the main beam direction so that a lateral region of light distribution is generated
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A lighting device for vehicles, having a flat light guide (1) containing two flat sides facing each other (5), one light input coupling surface(8) for the entry of light at a light input coupling side (3) of the flat light guide (1), one light output coupling surface (7) for the output of light input at the light input coupling surface (8) with the light output coupling surface (7) arranged at one light output coupling side (6) of the flat light guide (1) in such a manner that a specified light distribution (L) is generated, one narrow lateral surface (10, 10', 10'') connecting the flat sides (5) with each other and extending from one lateral border (11) of the light output coupling side (6), one collection surface (9) adjacent to the light input coupling surface (8) shaped in such a manner that a partial light beam of the entering light striking the collection surface (9) is reflected in total towards the light output coupling surface (7) without the partial light beam striking the narrow lateral surface (10, 10', 10''), with the light output coupling surface (7) featuring a number of protrusions (13) and depressions (14) alternately arranged in transverse to the main beam direction (H), with the protrusions (13) featuring at least two lateral slopes (15) tapered at an acute angle (α) and a tip surface (17), that the tip surface (17) is shaped in such a manner that a partial light beam (19) which has been totally reflected from the collection surface (9) and/or the flat sides (5) and an additional partial light beam originating directly from the light input coupling surface (8) are refracted at the tip surface (17) to generate a central region (L1) of light distribution (L), that the lateral slope (15) of the protrusion (13) is shaped in such a manner that another partial light beam (20, 21) of the input light striking the lateral slope (15) is totally reflected towards the tip surface (17) and exits the flat light guide (1) at the tip surface (17) to generate a lateral region (L2, L3) of light distribution (L).