Head-Up Display Cover Curvature Stray Light Reduction
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Solution Overview
Problem
The existing head-up display devices suffer from stray light issues due to the design of the opening cover, which can be noticeable when the device's height is lowered, and there is a need to reduce the overall height of the display while minimizing stray light.
Innovation Solution
A head-up display device with a light-transmissive cover having a downward convex shape, a first optical element that converges the display light, and a second optical element positioned to reflect the light towards the opening, where the distance between the display element and the first optical element, and the focal length of the first optical element satisfy a specific relationship, ensuring that the converged light intersects correctly and reduces stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the opening cover is designed with a curved surface to reduce device height, then the device height is reduced, but stray light occurs due to light reflecting off the cover
Solution Approach 1:
The patent converts the potentially harmful stray light reflection from the cover into a beneficial effect by carefully designing the cover's curved surface shape and positioning the display element such that reflected light is directed toward the projection area rather than creating unwanted glare. The cover curvature that could cause stray light is instead utilized to redirect light constructively.
Solution Approach 2:
The patent applies different surface properties to different parts of the cover. The cover has a curved surface with specific radius of curvature that is optimized to control light reflection patterns. Additionally, the display element is positioned at a specific distance from the cover, creating localized optical conditions that prevent stray light while maintaining compact height.
2Length of moving object
If the display element is positioned closer to the first optical element to reduce height, then the device becomes more compact, but optical performance may deteriorate
Solution Approach 1:
The patent optimizes specific parameters including the distance between the display element and the first optical element, the radius of curvature of the cover, and the positioning of the display element relative to the optical elements. These parameter optimizations allow the system to achieve compact dimensions while maintaining proper optical function and image quality.
Solution Approach 2:
The patent addresses the height constraint by optimizing the lateral positioning and optical configuration rather than simply increasing vertical distance. The display element is positioned at a specific lateral distance from the first optical element, and the cover's curved surface in the lateral dimension is designed to control light paths, allowing compact vertical profile without sacrificing optical performance.
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 inhibits stray light and allows for a reduced height of the head-up display device by optimizing the optical path and positioning of the elements, enabling a more compact design without increasing the height of the device.
Implementation Method 1
the first optical element has an effect of converging the display light
Implementation Method 2
a second optical element that is disposed ahead of the first optical element on a portion of the optical path of the display light after the first optical element, and reflects the display light toward the opening
Data Source
AI summary
A head-up display device includes: a housing including an opening at a top; a cover closing the opening; a display element housed in the housing; a first optical element on an optical path of display light from the display element; and a second optical element disposed on a portion of the optical path of the display light after the first optical element, and reflecting the display light toward the opening. The cover has a downward convex shape and includes a curved surface portion descending from a front end portion toward a rear end portion of the cover. The first optical element converges the display light. Among the display light emitted from a first end portion of the display element closer to the first optical element, light incident on an upper end portion of the first optical element travels toward a point below an upper edge of the second optical element.