Optical Extender for Vehicle HUD Eyebox Expansion
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Solution Overview
Problem
Current heads-up display (HUD) systems for vehicles are large and difficult to package due to limited eyebox size, short projection distance, and small virtual image, requiring larger curved mirrors to meet increasing demands, which complicates integration into constrained instrument panels and results in reduced image quality with holographic waveguides.
Innovation Solution
An optical extender with a multi-polynomial top surface is introduced between the main mirror and the windshield or aspheric combiner, modifying the light path to increase the eyebox size and projection distance without enlarging the HUD system's footprint, using a method that determines the shape based on vehicle geometry and desired parameters to create an improved optical path for the virtual image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the curved mirror is increased to improve eyebox size, then the eyebox size is improved, but the system size increases and becomes difficult to package
Solution Approach 1:
The optical system is segmented into multiple functional components: the curved mirror for image projection, the aspheric combiner for beam steering and image magnification, and the optical extender with multi-polynomial surface for eyebox expansion. This segmentation allows each component to be optimized independently, achieving large eyebox without proportionally increasing overall system size.
Solution Approach 2:
The optical extender acts as an intermediary component between the curved mirror and the aspheric combiner. It modifies the light path to expand the eyebox while maintaining a compact form factor, effectively mediating between the conflicting requirements of large eyebox and small system size.
2Length of stationary object
If the size of the curved mirror is increased to improve projection distance, then the projection distance is improved, but the system size increases and becomes difficult to package
Solution Approach 1:
The aspheric combiner and optical extender introduce additional optical dimensions and pathways that extend the effective projection distance without increasing the physical footprint of the system. The multi-polynomial surface creates complex light path folding that achieves long projection distance in a compact package.
3Area of moving object
If the size of the curved mirror is increased to improve virtual image size, then the virtual image size is improved, but the system size increases and becomes difficult to package
Solution Approach 1:
The aspheric combiner with multi-polynomial surface introduces sophisticated curvature variations that magnify the virtual image without requiring a larger curved mirror. The complex surface geometry manipulates light paths to achieve image magnification while maintaining compact system dimensions.
4Volume of moving object
If holographic waveguides are used to reduce system size, then the system size is reduced, but image quality deteriorates with fringing and color matching errors
Solution Approach 1:
Instead of using holographic waveguides that create images through diffraction and can suffer from quality issues, this patent uses a reflective optical system with a curved mirror and aspheric combiner that creates a direct optical copy of the display image. This approach maintains superior image quality with accurate color matching and no fringing artifacts while achieving compact packaging through clever optical design.
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 solution effectively increases the eyebox size and projection distance of HUD systems, allowing for larger virtual images without increasing the system's size, thereby improving packaging and image quality while preventing issues like fringing and color matching errors.
Implementation Method 1
The optical extender has a multi-polynomial top surface that modifies light in the light path to, when the light in the light path intersects the aspheric surface, create an optical path wherein a virtual image of the projection image is visible from an eyebox defined within a cabin of the vehicle.
Implementation Method 2
a main mirror to redirect and magnify the projection image towards an aspheric surface of the vehicle
Data Source
AI summary
Apparatus and method for designing an optical extender for a vehicle heads up display (HUD). An example vehicle includes a windshield and a HUD system. The HUD system includes an image source to provide a projection image and a main mirror to project the projection image onto the windshield. The image source and the main mirror define a light path. The HUD system also includes an optical extender between the main mirror and the windshield. The optical extender has a multi-polynomial top surface that modifies light in the light path to, when the light in the light path intersects the windshield, create an optical path wherein a virtual image of the projection image is visible from an eyebox defined within a cabin of the vehicle.