Automobile Headlight Double Mask System for Parasitic Ray Control
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Solution Overview
Problem
Existing optical modules for motor vehicle headlamps with split masks suffer from chromatic aberration issues, leading to parasitic rays above the desired cut-off, which are annoying and can cause dazzling, and existing solutions like black paint coatings are prone to peeling and additional manufacturing steps.
Innovation Solution
A double cover system with two optically active portions offset relative to the optical axis, where the second portion is inclined by at least 35°, and the first edge is inclined relative to the horizontal, eliminating parasitic rays by directing them away from the lens, without the need for absorbent coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a split mask is used to correct chromatic aberration, then chromatic aberration is reduced, but parasitic rays appear above the cut-off
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different zones of the mask. The first mask portion (correcting chromatic aberration) is kept reflective, while the second mask portion (controlling parasitic rays) is made absorbent. This localized differentiation allows each zone to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The mask is segmented into two distinct portions: a first portion for chromatic aberration correction and a second portion for parasitic ray control. This segmentation allows independent optimization of each portion's properties - the first portion maintains reflectivity for optical correction while the second portion uses absorbent material to eliminate parasitic rays.
2Object-generated harmful factors
If black paint coating is applied to the mask, then parasitic rays are suppressed, but manufacturing complexity increases and coating may peel off
Solution Approach 1:
The patent employs an absorbent coating on the second mask portion that is applied selectively only where needed, rather than coating the entire mask. This reduces the manufacturing complexity compared to full-mask coating, while still achieving parasitic ray suppression. The coating is applied in a controlled manner during assembly rather than as a separate manufacturing step.
3Object-generated harmful factors
If the second cache portion is inclined by at least 35°, then parasitic rays are redirected away from the lens, but the structure becomes more complex
Solution Approach 1:
The patent introduces asymmetry in the mask structure by inclining the second mask portion at a specific angle (at least 35°) relative to the first portion. This asymmetric configuration is optimized to redirect parasitic rays away from the lens while maintaining functional effectiveness. The asymmetric design is integrated into the overall mask geometry rather than added as a separate complex component.
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
Effectively suppresses parasitic rays above the cut-off without complicating the manufacturing process or risking coating deterioration, maintaining the module's anti-chromatic aberration properties throughout its life.
Implementation Method 1
the second portion is inclined, at least over part of its (upper) zone capable of receiving rays coming from the source or the reflector, by at least 35°... relative to the vertical or relative to the median plane of the first cache portion
Data Source
Figure 1a~3
Figure 4~6
Figure 5a~5e
AI summary
The module has a light source and a double mask system including two active optical mask portions (C1, C2) moved with respect to each other along an optical axis. The portion (C2) is inclined to 38-40 degree on a part of an upper zone (C22) with respect to a vertical or a median plane of the mask portion (C1), where the upper zone receives rays caused from the light source or a reflector. The mask portion (C2) has a shoulder (P) that delimits the upper part and a lower part (C21) of the portion (C2), where the lower part is inclined to an angle lower than or equal to 25 degree.