HUD Image Doubling Correction via Offset Compensation
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Solution Overview
Problem
Windscreens in viewing devices, such as HUDs, suffer from image doubling due to their two dioptres, leading to poor image quality and requiring costly solutions like reflective films or dedicated windscreen modifications.
Innovation Solution
Generating an initial image on the display as a succession of offset images, including both positive and negative versions of an ideal image, to ensure that the combined reflections from both dioptres result in a single, undistorted 'ideal' image perceived by the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a windscreen with two dioptres is used for protection, then protection function is improved, but image quality deteriorates due to image doubling
Solution Approach 1:
The invention applies preliminary action by pre-calculating and generating compensation images that anticipate the doubling effect. The system computes offset images with adjusted luminance values before display, so that when the windscreen naturally doubles the image, the secondary reflection perfectly compensates for the distortion, transforming a protective structure's defect into a corrected output.
Solution Approach 2:
The invention changes parameters by modifying the luminance values and positional offsets of compensation images based on the specific windscreen characteristics. By calculating the reflection coefficient k and offset (dx, dy) for each windscreen, the system adjusts the parameters of generated compensation images to match the actual doubling effect, enabling precise correction without physical modifications to the windscreen.
2Manufacturing precision
If reflective films or dedicated windscreens are used to eliminate image doubling, then image quality is improved, but cost and complexity increase
Solution Approach 1:
The invention replaces mechanical/optical correction systems (reflective films, prismatic inserts, dedicated windscreens) with a computational image processing system. Instead of physically modifying the windscreen or adding optical elements, the system uses software algorithms to generate compensation images that correct the doubling effect through digital processing and selective luminance adjustment.
Solution Approach 2:
The invention creates compensation images as copies of the original display image, offset by calculated amounts and adjusted in luminance. These copied images are generated in advance and superimposed on the original, allowing the system to correct the doubling effect by adding pre-computed image copies rather than using complex physical correction mechanisms.
3Manufacturing precision
If patches are applied to prioritize single reflection, then image doubling is reduced, but chromatic filtering and cost increase
Solution Approach 1:
The invention inverts the conventional approach by not trying to eliminate the second reflection, but rather generating an additional image specifically designed to be reflected by the second dioptre. Instead of blocking or minimizing the external reflection, the system creates a compensation image whose reflection perfectly matches and corrects the distortion caused by the windscreen's dual-dioptre structure.
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 approach eliminates the need for additional optical elements or windscreen modifications, reducing costs and allowing for wider fields of view, adaptability, and simpler implementation across various windscreen types without altering existing cockpit components.
Implementation Method 1
the optical combiner must have a single reflection surface of good optical quality. However, the windscreens are made up of at least two dioptres, an input face and an output face that cause, when the light flux is reflected on the windscreen, a doubling of the observed image.
Data Source
AI summary
The general technical field of the invention is that of viewing devices mounted on vehicles and comprising a display whose image is reflected by the windscreen of the vehicle, making it possible to superimpose the displayed image on the outside world. One of the major problems with this type of display is that the windscreen gives, by reflection, two non-superimposed doubled images. The basic principle of the invention is that the initial image is such that the combination of the first reflected image and the second image reflected by the windscreen gives a “clean” or “ideal” perceived image without any offsets. To perform this function, an image is generated on the display that comprises, obviously, the “ideal” image, but also a succession of offset images comprising negatives of the “ideal” image so that the resultant sum of the first reflected image and of the second reflected image includes no more than the “ideal” image. Obviously, the principle of the invention can be applied to simple displays or to displays comprising an image collimated to infinity or to a great distance.