Liquid Crystal Headlamp Control for Uniform Brightness
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Solution Overview
Problem
Vehicle lighting systems using liquid crystal elements often exhibit uneven brightness due to the viewing direction-dependent light transmission characteristics, which becomes pronounced during gradation control.
Innovation Solution
A vehicle lighting system with a control unit that adjusts the voltage across different regions of the liquid crystal element to optimize light transmission, and optionally uses a pair of lamp units with line-symmetrical or point-symmetrical viewing directions to reduce brightness differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light is made incident to the liquid crystal element at a wide angle including components inclined from the normal, then the illumination coverage is improved, but uneven brightness occurs due to viewing direction-dependent light transmission
Solution Approach 1:
The patent divides the light incident surface into multiple regions (first region with viewing direction incidence, second region with non-viewing direction incidence) and applies different voltage controls to each region. This local differentiation allows the system to maintain uniform brightness across the entire illumination area despite the wide-angle light incidence that would otherwise cause viewing direction-dependent brightness variations.
Solution Approach 2:
The patent changes the voltage parameter applied to different regions of the liquid crystal element. By setting the first voltage for the first region and the second voltage for the second region, the system adjusts the light transmission characteristics in each region to compensate for viewing direction effects, thereby achieving uniform brightness across the wide-angle illumination area.
2Ease of operation
If gradation control is applied to the liquid crystal element, then the light distribution pattern control is improved, but the uneven brightness phenomenon becomes more prominent
Solution Approach 1:
The patent implements region-specific voltage control where the first region (receiving light along the viewing direction) and the second region (receiving light from other directions) are controlled with different voltages. This local quality approach ensures that gradation control can be applied to adjust light distribution patterns while compensating for viewing direction-dependent brightness variations in each region, preventing the uneven brightness phenomenon from becoming prominent during gradation control.
Solution Approach 2:
The patent incorporates a control unit that manages the voltage application to different regions of the liquid crystal element. This feedback mechanism allows the system to adjust the voltage in each region based on the expected light incidence characteristics, thereby maintaining brightness uniformity even when gradation control is applied to create specific light distribution patterns.
3Device complexity
If a single lamp unit is used, then the device complexity is reduced, but the brightness uniformity across different viewing angles cannot be compensated
Solution Approach 1:
The patent achieves brightness uniformity compensation within a single lamp unit by dividing the light incident surface into multiple regions and applying different voltage controls to each region. This approach maintains relatively simple device structure while effectively compensating for viewing direction-dependent brightness variations through local quality differentiation in the voltage control strategy.
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 system effectively reduces uneven brightness by controlling light transmission across various regions of the liquid crystal element, ensuring more uniform illumination.
Implementation Method 1
an optical shielding unit which cuts off a part of light irradiated to the front from the light emitting unit and forms a cut-off suitable for the light distribution pattern of the vehicle headlamp, where the optical shielding unit is configured by an electro-optic element equipped with a light control function
Implementation Method 2
The control unit carries out electrical switching control of the electro-optic element to selectively control the light control portion, thereby changing the shape of the light distribution pattern
Implementation Method 3
a lens that projects the periphery of the vehicle the irradiation light formed by the liquid crystal element
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
To reduce uneven brightness of light irradiated from a vehicle lighting system. The system includes a lamp unit and a control unit where the lamp unit includes: a light source that emits light; a liquid crystal element using the light emitted from the light source to form irradiation light; and a lens projecting the irradiation light; where the light from the light source enters the element at an angle including a direction inclined from the normal of a light incident surface of the element; where the light incident surface has a first region in which most light enters from a viewing direction of the element and a second region in which most light enters from other directions, and where the control unit drives the element by setting a first voltage of the first region to be low and setting a second voltage of the second region to be high.