Head-Up Display Optical Layout for Distortion-Corrected Virtual Images
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Solution Overview
Problem
Conventional head-up display (HUD) systems face challenges in miniaturization while maintaining high visibility and reducing distortion and aberration of virtual images, as they require larger dimensions and complex configurations to achieve desired image size and magnification, and fail to effectively correct aberrations across varying windshield curvatures.
Innovation Solution
A head-up display apparatus with a concave mirror and a lens system where the optical distance between the mirror and the display panel is adjusted to correct distortion and aberration, using a concave mirror with a free-form surface and a lens with a concave surface to minimize the apparatus size and correct virtual image magnification differences caused by windshield curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the object point approaches the focal point to enlarge the virtual image size, then the magnification increases, but the mirror size becomes smaller and the effectively viewable range becomes limited
Solution Approach 1:
The patent introduces a folding mirror to change the optical path from a straight line to a folded configuration. This allows the light to travel a longer effective distance within a compact physical space, enabling high magnification without requiring a large mirror aperture. The folding mirror effectively adds a dimensional component to the optical path layout.
Solution Approach 2:
The folding mirror is positioned within the existing optical system structure, nesting the extended optical path within the compact housing. This allows the system to achieve a long effective optical distance (for high magnification) while maintaining a small physical footprint, similar to how nested dolls achieve large capacities within small outer dimensions.
2Measurement precision
If the distance from the concave mirror to the virtual image is increased to achieve desired magnification, then the image size is sufficient, but the dimension of the information display apparatus becomes larger
Solution Approach 1:
The folding mirror redirects the optical path in a non-linear fashion, allowing the light to traverse a longer effective distance (achieving desired magnification) while the physical apparatus maintains a compact dimension. The optical path length is decoupled from the physical apparatus length through the folding geometry.
3Manufacturing precision
If the upper and lower optical paths are made closer to reduce image magnification distortion, then the distortion is reduced, but the apparatus requires complex configurations and larger dimensions
Solution Approach 1:
The patent applies local quality by using a free-form surface on the concave mirror that is specifically designed to compensate for the magnification differences between upper and lower portions of the image. This localized surface modification corrects the distortion without requiring complex adjustments to the overall optical path geometry.
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 enables the formation of high-visibility virtual images with reduced distortion and aberration, achieving miniaturization of the HUD system while maintaining image quality across different viewpoints on a toroidal windshield.
Implementation Method 1
a concave mirror with a free-form surface... virtual image obtained by being reflected at an upper portion of a windshield
Implementation Method 2
a lens with a concave surface to minimize the apparatus size and correct virtual image magnification differences
Data Source
AI summary
A head-up display apparatus includes a display panel configured to display an image, and a reflecting mirror configured to reflect light from the display panel. An optical distance between the reflecting mirror and the display panel is changed to continuously change a display position of a virtual image from a distant place to an adjacent position such that a virtual image obtained by being reflected at an upper portion of a windshield is formed farther than a virtual image obtained by being reflected at a lower portion of the windshield when viewed from a viewpoint position of a driver.