Vehicle Headlight Lighting Device Polarization Control
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Solution Overview
Problem
Existing motor vehicle headlight systems suffer from reduced efficiency due to the need for two polarization filters, leading to light loss and potential overheating, especially at high illuminance, when using liquid crystal elements with unpolarized light sources.
Innovation Solution
The lighting device employs a polarizing beam splitter to divide light into two linearly polarized beam paths, with a Fresnel parallelepiped arrangement to convert one path's polarization to match the other, allowing a single liquid crystal element or LCoS to be illuminated efficiently, and a polarization filter to control light transmission, thereby minimizing light loss and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two polarization filters are used with unpolarized light sources, then the liquid crystal element can be properly controlled, but light loss increases and efficiency decreases
Solution Approach 1:
The patent segments the light path into two separate polarized beam paths using a polarizing beam splitter. Each beam path is independently processed through its own polarization rotation means, allowing the system to work with polarized light from the start and eliminate the need for the first polarization filter, thus reducing light loss while maintaining reliable liquid crystal control.
Solution Approach 2:
The patent applies preliminary polarization by using a polarizing beam splitter to divide the light into two polarized beam paths before the light reaches the liquid crystal element. This preliminary action ensures that the liquid crystal element receives properly polarized light, eliminating the need for the first polarization filter and reducing subsequent light loss.
2Reliability
If two polarization filters are used, then polarization control is achieved, but heat generation increases at high illuminance
Solution Approach 1:
By segmenting the light path into two polarized beams and processing each separately with polarization rotation means, the system eliminates the need for the first polarization filter. This removes a major heat-generating component while maintaining precise polarization control through the polarization rotation means and second polarization filter.
Solution Approach 2:
The patent introduces polarization rotation means as an intermediary between the polarizing beam splitter and the liquid crystal element. This intermediary component rotates the polarization of each beam path independently, allowing the system to maintain polarization control without requiring the first polarization filter, thereby reducing heat generation.
3Loss of energy
If a polarizing beam splitter with two beam paths is used, then light utilization efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the two polarized beam paths after they have been independently processed by their respective polarization rotation means. The reflective means combines the first beam path with the second beam path, allowing both processed beams to contribute to illuminating the liquid crystal element, thus maintaining high light utilization efficiency while managing complexity through systematic integration.
Solution Approach 2:
The polarization rotation means act as intermediaries that process each beam path independently before merging. This modular approach allows the system to maintain high light utilization efficiency by processing both beams while managing complexity through standardized intermediate processing stages.
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 configuration enhances the efficiency of the lighting device by utilizing the entire light flux and reducing heat issues, allowing for improved light distribution and functionality in various beam functions like low beam, high beam, and fog lighting.
Implementation Method 1
a polarizing beam splitter which is connected downstream of the at least one attachment optics and divides the light beams collimated by the attachment optics into a first and a second linearly polarized Splits the beam path, the polarization directions of the beam paths being rotated 90° to one another
Implementation Method 2
a Fresnel parallelepiped arrangement to convert one path's polarization to match the other
Implementation Method 3
a single liquid crystal element or LCoS to be illuminated efficiently, and a polarization filter to control light transmission, thereby minimizing light loss and heat generation
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Lighting device (51, 52, 53) for a motor vehicle headlight, comprising: - a light source (100) whose light beams can be collimated by at least one optic (200), - a polarizing beam splitter (300) that divides the collimated light beams into a first and a second linearly polarized beam path (310, 320), - a first means for polarization rotation (400) which is configured to rotate the polarization direction of the second beam path (320) so that the second beam path (320) has the polarization direction of the first beam path (310), - a reflective means (350) which is configured to deflect the first beam path (310), - a single second means for polarization rotation (600) which comprises at least one segment which can be switched to an active and an inactive state by means of electrical signals, - a polarization filter means (610),which is configured to transmit or block the light rays rotated with respect to polarization by the second means for polarization rotation (600), and - at least one projection lens (700) which is provided for generating a light distribution or a partial light distribution of a light function in front of a motor vehicle.