Head-up Display Diffuser for Curved Windscreens
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Solution Overview
Problem
Conventional head-up displays for vehicles with non-flat windscreens suffer from image distortion and high production costs due to the need for custom-made optics to correct for the windscreen's spatially variant optical power.
Innovation Solution
A head-up display system utilizing a modified diffuser with spatially variant optical power, specifically a freeform diffuser shaped to compensate for the windscreen's curvature, combined with a standard parabolic mirror to maintain image quality and reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If custom-made optics are used to correct for the windscreen's spatially variant optical power, then image quality is improved, but production cost increases
Solution Approach 1:
The patent applies local quality by implementing a freeform diffuser with spatially variant optical power that is specifically tailored to compensate for the particular windscreen's curvature characteristics. Instead of using uniform correction optics, the diffuser's optical properties are locally optimized at different positions to match the spatially variant distortion caused by the curved windscreen, thereby achieving high image quality correction without requiring completely custom-made complex optical systems.
Solution Approach 2:
The patent utilizes parameter changes by modifying the optical power distribution of the diffuser to match the windscreen's curvature parameters. The freeform diffuser is designed with spatially varying optical parameters that correspond to the measured windscreen geometry, allowing the system to adapt to different windscreen curvatures by changing the diffuser's optical parameters rather than redesigning the entire optical system.
2Ease of manufacture
If standard optics are used, then production cost is reduced, but image distortion occurs due to non-flat windscreen curvature
Solution Approach 1:
The patent introduces a freeform diffuser as an intermediary element between the projection system and the windscreen. This diffuser acts as a mediator that pre-compensates for the windscreen's curvature distortion by having spatially variant optical power that counteracts the windscreen's spatially variant optical power. This allows standard optics to be used while still achieving corrected image quality through the intermediary diffuser.
3Manufacturing precision
If custom optics are designed for each windscreen, then image distortion is corrected, but device complexity increases
Solution Approach 1:
The patent extracts the correction function from the main optical system and places it in a separate freeform diffuser component. By taking out the complex correction requirements from the overall optical design and implementing them in a dedicated diffuser element with spatially variant optical power, the system achieves precise image correction while keeping the rest of the optical system relatively simple and using standard components.
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 a high-quality virtual image with reduced production costs by using a standard parabolic mirror and a custom-shaped diffuser, effectively addressing image distortion caused by non-flat windscreens.
Implementation Method 1
Light scattered from an object contains both amplitude and phase information
Implementation Method 2
Each phase modulating element, or pixel, may vary in state to provide a controllable phase delay to light incident on that phase modulating element
Implementation Method 3
The position of the reconstruction in space may be controlled by using an optical Fourier transform lens, to form the holographic reconstruction, or 'image ', in the spatial domain
Implementation Method 4
A head-up display for a windscreen... forming a virtual image of the image using the windscreen
Data Source
AI summary
A head-up display for a windscreen having spatially variant optical power. The head-up display includes a diffuser arranged to display an image. The diffuser is shaped to compensate for the spatially variant optical power of the windscreen. A holographic projector may be provided, which is arranged to project the image for display onto the diffuser and includes a spatial light modulator arranged to apply a phase-delay distribution to incident light. The phase-delay distribution includes phase-only data representative of an object. The projector further includes Fourier transform means arranged to perform a Fourier transform of phase modulated light received from the spatial light modulator and to form the image on the diffuser.