Curved Optical Waveguide for HUD Stray Light Suppression
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Solution Overview
Problem
Existing head-up displays for vehicles face challenges in mitigating the effects of sunlight reflections, which can cause glare and safety hazards due to the inability to effectively manage stray light.
Innovation Solution
The design incorporates a curved optical waveguide with a coupling area that directs incident light perpendicular to the propagation axis, allowing for total internal reflection and concentration of light onto a glare protection area, thereby absorbing stray light and preventing it from reaching the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a flat optical waveguide is used, then total internal reflection occurs effectively, but stray light is reflected towards the user causing glare
Solution Approach 1:
The patent applies curvature to the boundary surfaces of the optical waveguide, transforming flat interfaces into curved surfaces. This curvature causes incident stray light to be reflected in different directions rather than uniformly, directing it away from the user's eye while maintaining optical guidance functionality through controlled curvature radius
2Volume of moving object
If the optical waveguide expands in the direction of propagation, then space utilization improves, but curvature in the propagation direction complicates total internal reflection
Solution Approach 1:
The patent introduces asymmetric curvature where the radius of curvature is significantly larger in the propagation direction compared to the transverse direction. This asymmetric design allows the waveguide to expand and utilize space effectively while maintaining conditions suitable for total internal reflection by minimizing curvature effects in the critical propagation direction
3Object-affected harmful factors
If a curved surface is used to concentrate light, then stray light is redirected to glare protection, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies appropriate ranges for the radius of curvature parameter to balance optical performance and manufacturability. By optimizing this parameter within a specific range, the design achieves effective stray light redirection while maintaining feasibility for standard manufacturing processes, avoiding excessively tight tolerance requirements
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 solution effectively neutralizes the impact of stray light, ensuring a safer and more reliable display experience by minimizing glare and optimizing the use of space within the head-up display system.
Implementation Method 1
an optical waveguide with interfaces at which total internal reflection occurs
Data Source
Figure 1
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AI summary
The invention relates to a device for displaying a virtual image (VB). The device has an imaging unit (100), an optical waveguide (5) with boundary surfaces (51001, 51002, 52001, 52002), at which total inner reflection occurs, and an optical waveguide (510, 520) which widens in a first direction (y, x). At least one of the boundary surfaces (51001, 51002, 52001, 52002) of the widening optical waveguide (510, 520) is a curved surface.