Liquid Crystal Headlamp Control for Uniform Wide-Angle Illumination
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Solution Overview
Problem
Vehicle headlamps using liquid crystal elements often exhibit uneven brightness due to the viewing direction-dependent light transmission characteristics, which becomes pronounced during gradation control, leading to light unevenness when irradiating the front of a vehicle.
Innovation Solution
A vehicle lighting system with a lamp unit and a control unit that uses a liquid crystal element, where light is incident at a wide angle with different voltage settings for regions aligned with and not aligned with the viewing direction, and the lamp units are arranged to have 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 of the light incident surface, then the light distribution pattern can be expanded to cover a wider area, but uneven brightness occurs due to the viewing direction dependence of the liquid crystal element
Solution Approach 1:
The patent divides the light incident surface of the liquid crystal element into multiple regions (first region and second region) with different light incident angle characteristics. The first region receives light mainly from directions along the viewing direction, while the second region receives light mainly from directions not along the viewing direction. This local differentiation allows each region to maintain appropriate brightness characteristics while collectively achieving wide-area illumination.
Solution Approach 2:
The light incident surface is segmented into distinct regions based on the direction of light incidence relative to the viewing direction of the liquid crystal element. By controlling which regions receive light from which directions, the system can manage the viewing angle dependence of the liquid crystal element to reduce uneven brightness while maintaining wide coverage.
2Manufacturing precision
If gradation control is applied to the irradiation light, then the light distribution pattern can be precisely adjusted, but the uneven brightness phenomenon becomes more prominent
Solution Approach 1:
The patent applies different control strategies to different regions of the liquid crystal element. The first region, which receives light along the viewing direction, is controlled with different voltage characteristics than the second region, which receives light from other directions. This regional differentiation allows gradation control to be applied while compensating for viewing angle effects to maintain brightness uniformity.
3Device complexity
If a single light source is used to simplify the system structure, then device complexity is reduced, but it becomes difficult to control light incidence from multiple directions simultaneously
Solution Approach 1:
The patent introduces a spatial dimension to light control by utilizing light incident surfaces oriented in different directions. Instead of adding multiple light sources, the system uses the directional characteristics of a single light source in combination with multi-directional light incident surfaces to achieve control over light incidence from different directions.
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 reduces uneven brightness by controlling light transmission across different regions of the liquid crystal element, resulting in more uniform irradiation light distribution.
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
a lens that projects the periphery of the vehicle the irradiation light formed by the liquid crystal element
Data Source
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.