Vehicle Headlight Reflector Geometry for Tolerance-Stable Cut-Off
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Solution Overview
Problem
Existing light modules for motor vehicle headlights suffer from positioning issues that lead to significant variations in light intensity distribution due to the close proximity of the light source to the reflector, complicating thermal management and making them sensitive to manufacturing and assembly tolerances.
Innovation Solution
A light module design with a reflector featuring a kinked horizontal edge and a horizontally oriented light source, allowing for improved positioning of the PCB upright, which reduces the solid angle covered by the reflector, thereby minimizing the impact of positional variations and enhancing thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the light source is positioned close to the reflector to shape the cut-off line, then the light intensity distribution can be controlled, but the system becomes highly sensitive to position deviations and thermal management becomes difficult
Solution Approach 1:
The patent introduces a vertical dimension to the reflector edge geometry by creating a stepped or tiered structure. Instead of a simple planar edge, the reflector has multiple levels with different heights, allowing the cut-off line to be shaped in three-dimensional space. This dimensional change increases the effective distance between the light source and the critical edge regions, reducing sensitivity to position deviations while maintaining light distribution control through the complex geometry's optical projection.
Solution Approach 2:
The reflector's horizontal edge is divided into multiple segments or steps at different heights. This segmentation creates multiple distinct regions that project different portions of the light beam, allowing independent control over the cut-off line shape. The segmented structure provides tolerance to position variations because each segment can be optimized independently, and the overall light distribution is the composite effect of these segments rather than relying on a single critical edge position.
2Ease of manufacture
If the PCB is positioned horizontally below the light source, then the light module can be assembled, but thermal management becomes ineffective due to heat accumulation
Solution Approach 1:
The patent repositions the PCB from a horizontal arrangement below the light source to a vertical arrangement at the rear of the light module. This dimensional change in PCB orientation creates an open pathway for hot air to rise vertically away from the light source and PCB assembly, eliminating the heat accumulation trap that occurred with horizontal positioning. The vertical PCB placement aligns with the natural convection current direction, enabling effective passive thermal management while maintaining assembly feasibility through standardized mounting structures.
3Use of energy by moving object
If the reflector covers a large solid angle, then light collection is maximized, but positioning freedom is reduced and tolerances become more critical
Solution Approach 1:
The patent applies different geometric characteristics to different regions of the reflector. The main body of the reflector maintains a large solid angle for efficient light collection, while the horizontal edge regions are modified with stepped or tiered structures that create specific optical projections. This local differentiation allows the reflector to simultaneously achieve high light collection efficiency through its overall geometry and positioning flexibility through the specialized edge structures, as the local edge modifications provide tolerance to position variations without compromising the global light gathering capability.
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 design provides greater freedom in positioning the light source and PCB, reducing sensitivity to manufacturing and assembly tolerances, and improves thermal dissipation, resulting in a more stable and efficient light intensity distribution.
Implementation Method 1
a reflector with a concave reflective surface configured to collect and reflect the light rays emitted by the light source into a light beam along an optical axis of the light module
Implementation Method 2
an optical system configured to project the light beam and to form an image of the reflective surface of the reflector
Data Source
AI summary
A light module is provided. The light module includes: a light source capable of emitting light rays around a main emission direction; and a reflector with a concave reflective surface configured to collect and reflect the light rays emitted by the light source into a light beam along an optical axis of the light module. The reflector includes: a front edge running perpendicular to the optical axis; a lateral edge running perpendicular to the main emission direction; and a horizontal edge featuring two segments running in distant planes substantially parallel to both the main emission direction and the optical axis, said segments being connected by a kink segment. The invention further includes an optical system configured to project the light beam and to form an image of the reflective surface of the reflector.