Wedge-Shaped Combiner for Head-Up Display Double Image Elimination
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Solution Overview
Problem
Conventional head-up displays suffer from double images due to optical path differences between the inner and outer surfaces of the combiner, leading to unclear display information and increased costs when using specialized glass structures to mitigate this issue.
Innovation Solution
A head-up display design featuring a combiner with a wedge-shaped cross-section and arc-shaped optical surfaces, where the front surface forms a first arc-shaped optical surface and the rear surface forms a second arc-shaped optical surface with a greater curvature, ensuring that display images reflected from both surfaces coincide in size and position, preventing double images and allowing for use with standard glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thin plate-shaped combiner is used to reflect display light rays toward the driver, then the driver can see display information on the windshield, but double images occur due to optical path differences between the inner and outer surfaces of the combiner
Solution Approach 1:
The combiner is designed with a wedge shape where the thickness varies in one direction, creating asymmetric optical paths. This asymmetric geometry causes light rays reflected from the inner and outer surfaces to converge at the same position, eliminating double images while maintaining the combiner's reflective function
Solution Approach 2:
The solution transitions from a two-dimensional flat plate combiner to a three-dimensional wedge-shaped combiner with varying thickness. This dimensional change introduces a gradient in the optical path length that compensates for the path difference between inner and outer surface reflections, causing the reflected images to coincide
2Manufacturing precision
If an antireflection film is applied to the rear surface of the combiner to suppress reflected light rays, then double images are prevented, but the total cost of the head-up display increases
Solution Approach 1:
The invention replaces the expensive antireflection film treatment with a wedge-shaped combiner structure that can be manufactured using standard glass or plastic materials. This geometric solution is more cost-effective while achieving the same image clarity goal by eliminating double images through optical path convergence
Solution Approach 2:
The solution changes the physical parameter of the combiner from a uniform thickness plate to a variable thickness wedge shape. This parameter change modifies the optical path length gradient, causing reflected light rays from both surfaces to converge at the same position, thereby eliminating double images without requiring additional costly coatings
3Manufacturing precision
If a front glass with a three-layer structure is used as a combiner to make reflected light rays overlap, then double images are reduced, but the device complexity increases
Solution Approach 1:
The invention extracts the essential function of eliminating double images from the complex three-layer structured front glass and implements it through a simple wedge-shaped combiner with variable thickness. This simplifies the overall device structure while maintaining the ability to converge reflected light rays from inner and outer surfaces to the same position
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 enables clear and stable display of information without double images, reducing costs by allowing the use of general front glass and improving user experience by maintaining focus on the windshield without frequent line-of-sight changes.
Implementation Method 1
a combiner 23 (a reflection member) formed on a surface of the windshield 21. Accordingly, the driver is allowed to be able to recognize display light rays 24 (display image) which forms a virtual image overlapping a scene in front of the windshield through the windshield
Implementation Method 2
the front surface of the combiner forms a first arc-shaped optical surface which receives and reflects the display light rays emitted from the display device toward the driver so that the driver sees a first virtual image of the display light rays with a set magnification greater than 1 on the outside of the windshield, and the rear surface forms a second arc-shaped optical surface which receives and reflects the display light rays emitted from the display device toward the driver so that the driver sees a second virtual image which coincides with the first virtual image
Data Source
AI summary
A head-up display includes a display device and a combiner that has a rear surface brought into contact with an inner surface of a windshield of a vehicle, and reflects a display light rays emitted from the display device by a front surface of the combiner toward a driver in the vehicle. The front surface forms a first arc-shaped optical surface which receives and reflects the display light rays toward the driver so that the driver sees a first virtual image of the display light rays with a set magnification greater than 1 on the outside of the windshield. The rear surface forms a second arc-shaped optical surface which receives and reflects the display light ray toward the driver so that the driver sees a second virtual image which coincides with the first virtual image in terms of the size and position on an outside of the windshield.