Ghost Image Free HUD via Field Lens Projection
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Solution Overview
Problem
Existing head-up display (HUD) systems suffer from ghost images due to reflections off windscreen surfaces, which are exacerbated by larger tilting angles and thicker windscreens in vehicles like trucks and buses, and current mitigation methods are costly and visually unappealing.
Innovation Solution
An image generation system using a display screen with a field lens and anisotropic optical components that project light to form virtual images at different distances, ensuring the offset between primary and ghost images is below the threshold of human resolution, eliminating the ghost image without modifying the screen or internal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a special multi-layer wedged windscreen is used to overlap reflected images, then ghost image elimination is achieved, but manufacturing cost and device complexity increase significantly
Solution Approach 1:
The patent introduces a field lens as an intermediary optical component between the image source and the windscreen. This lens projects the image at a controlled distance such that the offset between front-surface and back-surface reflections is minimized, effectively using the lens as a mediator to manage the ghost image problem without modifying the windscreen itself.
Solution Approach 2:
The patent changes the projection distance parameter controlled by the field lens to optimize image overlay. By adjusting the projection distance, the system achieves optimal overlap between primary and ghost images, reducing ghost image visibility through parameter optimization rather than structural modification.
2Adaptability or versatility
If the windscreen tilting angle is increased for larger vehicles, then vehicle design flexibility is improved, but ghost image offset increases making the problem more prominent
Solution Approach 1:
The patent creates a universal solution that works across different vehicle types and windscreen configurations. The field lens system is designed to accommodate various tilting angles and windscreen thicknesses, providing ghost image mitigation that is adaptable to multiple applications without requiring vehicle-specific customization.
Solution Approach 2:
The system adjusts the projection distance parameter through the field lens to compensate for different windscreen tilting angles. By changing the projection parameters dynamically, the system maintains effective ghost image overlap across various vehicle configurations, from cars to trucks and buses.
3Object-affected harmful factors
If conventional mitigation techniques are applied to windscreens with large tilting angles, then ghost image reduction is achieved, but system cost increases
Solution Approach 1:
The field lens serves as a cost-effective intermediary component that manages ghost image formation through optical parameter control rather than expensive windscreen modifications. This approach replaces costly wedged windscreens or nanoparticle coatings with a relatively simple lens-based solution.
Solution Approach 2:
The system creates a virtual copy of the image at a controlled projection distance, allowing the ghost image to be positioned in optimal overlap with the primary image. This copying approach at controlled distance is more economical than physical windscreen modifications.
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
This solution provides a ghost image-free HUD system that can project images at shorter distances, is adaptable to various windscreen angles, and maintains image quality without the need for costly modifications or special windscreen designs.
Implementation Method 1
an anisotropic optical component configured to magnify the first and second virtual image along the second axis only
Implementation Method 2
the field lens is configured to project the first virtual image at a first projection distance and the second virtual image at a second projection distance
Implementation Method 3
a portion of the light is reflected by the front surface of the display screen forming a first virtual image, a portion of the light is transmitted through the display screen and is incident on the back surface of the display screen forming a second virtual image
Data Source
AI summary
An image generation system for providing a ghost image free head-up display, the system comprising a display screen having a front surface and a back surface, a picture generation unit for projecting an image towards the display screen for reflection towards an eye box, a field lens, and an anisotropic optical component having a first optical power along a first axis and second optical power along a second axis, wherein the first and second axis are perpendicular, wherein the picture generation unit is configured to project light through the field lens such that light is incident on the front surface of the display screen forming a first virtual image, wherein a portion of the light is transmitted through the display screen and is incident on the back surface of the display screen forming a second virtual image, wherein the first and second virtual images are offset along the first axis, wherein the field lens is configured to project the first virtual image at a first projection distance and the second virtual image at a second projection distance such that the offset is below a threshold magnitude and the first and second virtual images are substantially overlaid as viewed from the eye box, and wherein the anisotropic optical component is configured to magnify the first and second virtual image along the second axis only.