Head-Up Display Optics for Road-Aligned Virtual Image Contrast
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Solution Overview
Problem
Conventional head-up displays experience contrast reduction when displaying virtual images along a road surface, which affects the clarity and effectiveness of the augmented reality display for drivers.
Innovation Solution
A head-up display configuration that includes a projection optical system with a first optical element and a second optical element, where the local powers of these elements satisfy specific conditional expressions, reducing the inclination angle of the display device and preventing contrast reduction, allowing for clear virtual image display along a road surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the display device is inclined significantly to display a virtual image along the road surface, then the virtual image can be displayed in the correct orientation, but the contrast of the display device is reduced
Solution Approach 1:
The projection optical system is divided into multiple optical elements (first optical element and second optical element) with different functions. The first optical element handles magnification while the second optical element controls the inclination angle, allowing independent optimization of each function to resolve the contradiction between image orientation and display contrast.
Solution Approach 2:
The first optical element is designed with specific local optical properties (positive or negative power) to achieve magnification, while the second optical element has different local properties to control the inclination angle. This local differentiation allows each element to optimize its specific function without compromising the other, maintaining contrast while achieving proper image orientation.
2Illumination intensity
If the inclination angle of the display device is reduced to prevent contrast reduction, then the contrast is maintained, but the virtual image cannot be properly oriented along the road surface
Solution Approach 1:
The second optical element acts as an intermediary between the display device and the windshield. It receives light from the display device and modifies the optical path to achieve the desired inclination angle for the virtual image, allowing the display device itself to maintain a small inclination angle for high contrast while the intermediary element provides the necessary orientation adjustment.
Solution Approach 2:
The solution moves from adjusting the inclination in one dimension (display device angle) to controlling the virtual image orientation through multiple dimensions (optical path manipulation by multiple elements). The first and second optical elements work together to achieve proper image orientation along the road surface while the display device maintains a minimal inclination angle.
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 prevents contrast reduction and enhances the clarity of virtual images displayed along a road surface, improving driver cognition and the naturalness of the augmented reality experience.
Implementation Method 1
a projection optical system configured to magnify and project the display image, the projection optical system including a first optical element and a second optical element arranged in order of an optical path from the display image
Data Source
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AI summary
The present disclosure provides a head-up display capable of displaying a virtual image along a road surface without reducing a contrast of a display device. A head-up display (100) displaying a virtual image (I) includes a display device (110) and a projection optical system (140); the projection optical system (140) includes a first optical element (123) and a second optical element (125) arranged in order of an optical path from the image; and when optical paths corresponding to an upper end and a lower end of the virtual image are defined as an upper ray (Lu) and a lower ray (Ll), respectively, and a diverging effect and a converging effect are defined as being negative and positive, respectively, the first optical element and the second optical element satisfy conditional expressions P_u1-P_l1<0 and P_u2-P_l2>0 (where P_u1 denotes a local power of the first optical element acting on the upper ray, P_l1 denotes a local power of the first optical element acting on the lower ray, P_u2 denotes a local power of the second optical element acting on the upper ray, and P_l2 denotes a local power of the second optical element acting on the lower ray).