Vehicle Headlight Beam Control During Temperature Derating
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Solution Overview
Problem
Temperature derating of light emitting units in vehicle headlights leads to deterioration in frontal visibility due to darkening of the additional light distribution pattern, particularly affecting the upper and lower edge sides, which can cause discomfort and reduced visibility for drivers.
Innovation Solution
A vehicle headlight system with a controller that adjusts the inclination of light source units to move the upper edge of the low beam light distribution pattern upward before or after temperature derating, ensuring the lower edge side of the additional light distribution pattern remains bright, thereby preventing the formation of intensity valleys that could cause visibility issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature derating is performed on the second light source unit to protect it from heat, then the light emitting unit is protected from heat damage, but the additional light distribution pattern becomes dark and frontal visibility deteriorates
Solution Approach 1:
The upper edge of the low beam light distribution pattern is moved upward before temperature derating is performed. This preliminary action ensures that when the additional light distribution pattern darkens due to duty ratio reduction, the upwardly moved low beam pattern provides compensating illumination in the upper and lower edge regions, preventing visibility deterioration.
Solution Approach 2:
The patent applies different control strategies to different regions of the light distribution pattern. The upper edge of the low beam pattern is specifically adjusted to compensate for darkening in the additional light distribution pattern's edge regions, while the center region maintains its original characteristics. This localized adjustment ensures visibility is maintained where it is most needed without affecting overall system performance.
2Illumination intensity
If the upper edge of the low beam light distribution pattern is moved upward after temperature derating, then visibility can be improved, but two peaks are formed in the intensity distribution creating a dark valley that worsens visibility
Solution Approach 1:
The upper edge movement is performed before temperature derating rather than after. This timing ensures that the low beam light distribution pattern is already in its adjusted position when the additional light distribution pattern darkens, preventing the formation of a dark valley between two peaks and maintaining uniform illumination across the high beam pattern.
Data Source
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AI summary
A vehicle headlight (1) includes a first light source unit (20), a second light source unit (40), and a controller (CO), in which the controller (CO) moves at least an upper edge of a low beam light distribution pattern (101) upward in a case of performing temperature derating on the second light source unit (40) based on a temperature of the second light source unit (40) in a state where a high beam light distribution pattern (105) is formed.