Anti-glare Venetian Blind for Head-up Display Stray Light
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Solution Overview
Problem
Conventional head-up displays suffer from stray light reflections that reduce image contrast and are limited by the size of the eyebox, which restricts viewer positioning, and existing anti-reflective solutions compromise performance or require significant installation space.
Innovation Solution
An anti-glare element comprising a Venetian blind with slats supported by an integral spring mechanism that allows precise, temperature-independent angle adjustment, enabling effective shading of stray light while maintaining a large eyebox.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If reflective components are tilted to prevent reflections, then stray light is reduced, but installation space increases and component performance is compromised
Solution Approach 1:
Instead of tilting the anti-reflective component to redirect stray light away from the eyebox, the patent inverts the approach by using a flat component that absorbs stray light through a black coating. The component remains perpendicular to the optical axis, eliminating the need for additional installation space while maintaining stray light reduction effectiveness.
Solution Approach 2:
The patent converts the harmful stray light reflections into a beneficial effect by using a black coating that absorbs the stray light. The black coating transforms the harmful reflected light into absorbed energy, preventing it from reaching the viewer's eye while maintaining the compact flat structure of the component.
2Object-affected harmful factors
If anti-reflective coatings are applied to reduce reflections, then reflection intensity is reduced, but the coatings reduce achievable light intensity
Solution Approach 1:
The patent applies the black anti-reflective coating only to specific regions where stray light is generated, rather than coating the entire optical component. This localized application reduces reflections in critical areas while preserving light transmission in areas where it is needed for the main optical path.
Solution Approach 2:
The patent uses a partial coating approach, applying the black coating only to the extent necessary to reduce stray light reflections. This partial action is sufficient to eliminate the harmful reflections without excessively reducing the overall light intensity that reaches the viewer.
3Adaptability or versatility
If the eyebox is enlarged to allow more viewing positions, then viewer positioning freedom increases, but the optical unit size must increase
Solution Approach 1:
The patent replaces the mechanical approach of enlarging the optical unit with an optical approach using a fiber optic plate. The fiber optic plate dilates the exit pupil optically, allowing a larger eyebox without increasing the physical size of the optical unit. This substitution enables the system to maintain a compact form factor while providing extended viewing flexibility.
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 provides enhanced image contrast by reducing stray light reflections and enlarges the eyebox without compromising installation space, offering precise and adaptable shading to suit various viewer positions and environmental conditions.
Implementation Method 1
The light coupled into the optical fiber is totally reflected at its interfaces and is thus guided within the optical fiber.
Implementation Method 2
The integral spring has a flexible mechanism. This has the advantage of enabling freedom from hysteresis and play, which leads to precise adjustment.
Implementation Method 3
the angle of incidence is independent of temperature, since heat-induced expansion of the integral spring may change its overall length but not its basic shape.
Implementation Method 4
The anti-glare element is a Venetian blind comprising a plurality of slats whose angle of incidence is defined by at least one integral spring.
Data Source
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AI summary
The present invention relates to an apparatus for generating a virtual image (VB), comprising: - a display element (11) for generating an image; - an optical waveguide (5, 510, 520) for expanding an exit pupil and - an anti-glare element (81) arranged in the beam path downstream of the optical waveguide (5), said anti-glare element (81) being designed as a blind (83) having a plurality of slats (82) the pitch (α) of which is defined by at least one one-piece spring (7, 7', 7a).