Vehicle Light Guide Surface Geometry for Cut-Off Line Accuracy
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Solution Overview
Problem
Imaging errors, particularly distortion, occur in lighting devices as the horizontal distance from the optical axis increases, causing the cut-off line in the light image to be inclined or bent downwards, and reducing light emission in the desired areas.
Innovation Solution
The upper light deflection surface is modified in specific regions laterally of the vertical longitudinal plane, with intersection curves having an average inclination greater than the longitudinal axis intersection curve, ensuring light rays are reflected differently to compensate for imaging errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional light guide body with a standard upper light deflection surface is used, then the device structure is simple and easy to manufacture, but imaging errors occur causing the cut-off line to be inclined or bent downwards at increased horizontal distances from the optical axis
Solution Approach 1:
The upper light deflection surface is modified only in specific lateral regions away from the vertical longitudinal plane, while maintaining the standard shape in other areas. This localized modification approach corrects imaging errors in specific zones without unnecessarily complicating the entire light guide body structure, thus balancing manufacturing precision improvement with device complexity control
Solution Approach 2:
The patent introduces a new dimensional characteristic to the upper light deflection surface by creating regions with different average inclinations relative to the horizontal reference plane. This dimensional variation in the surface geometry enables correction of imaging errors that occur at different lateral distances, improving cut-off line accuracy without requiring complete structural redesign
2Manufacturing precision
If the upper light deflection surface is modified to correct imaging errors, then the cut-off line accuracy is improved, but the manufacturing complexity increases
Solution Approach 1:
By applying surface modifications only to specific lateral regions rather than the entire upper light deflection surface, the patent minimizes the impact on manufacturing processes. The modified regions are clearly defined by their lateral position and average inclination characteristics, allowing for targeted manufacturing approaches that reduce overall fabrication complexity
Solution Approach 2:
The patent modifies specific geometric parameters of the upper light deflection surface, namely the average inclination angles of intersection curves in lateral regions. By carefully selecting and implementing specific parameter changes rather than complete redesign, the cut-off line accuracy is improved while keeping manufacturing processes relatively straightforward
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 modified deflection surface ensures that light rays emerge at a consistent height, maintaining a straight cut-off line and appropriate light distribution across varying lateral distances from the optical axis.
Implementation Method 1
Light emitted by the light source travels through the light guide body mainly via total internal reflection to the light exit surface
Implementation Method 2
Light emitted by the at least one light source and coupled into the light guide body via the light coupling region propagates in the light guide body, is deflected from the upper light deflection surface to the lower light deflection surface and deflected from the lower light deflection surface to the light exit surface, and exits the light guide body via the light exit surface, passes through the projection optics device and is imaged from the projection optics device as a light distribution with a cut-off line
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
A lighting device (1) for a vehicle, particularly a motor vehicle, comprises at least one light source (10) configured to emit light, a transparent light guide body (100), at least one light coupling area (101) to couple light from the light source (10) into the light guide body (100), and a projection optics device (200) with an optical axis (X) and a focal point (F). The light guide body (100) has an upper light deflection surface (102), a light exit surface (104), and a lower light deflection surface (103). The light travels through the guide body (100), deflects between surfaces (102) and (103), and exits via the exit surface (104). Regions (BE; BE1; BE1' ... BE10') of the upper light deflection surface (102) deviate in shape from the vertical longitudinal plane (LE), resulting in intersection curves (SK1, SK2, SK3; SK1', SK2', SK3') with greater average inclinations (α1, α2) than the longitudinal axis intersection curve (SK0).