Eye-Tracked Light Field Display for Wide-View HUDs
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Solution Overview
Problem
Existing head-up displays (HUDs) face challenges in automotive applications due to space constraints, limited fields of view, and disparities in focus distances between virtual and real-world environments, while stereoscopic displays introduce obstructions and waveguides are constrained by manufacturing complexities, leading to impractical setups.
Innovation Solution
A light field display system that utilizes an optical combiner to reflect synthetic light fields based on the relative location of viewers, combining virtual content with real-world light fields, allowing for a large field of view and high-quality, depth-perceiving images without the need for additional glasses or large projection optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a separate optical combiner is incorporated in proximity of the viewer, then large projection surfaces can be created, but the device complexity increases and space constraints are violated
Solution Approach 1:
The patent merges the combiner and display into a single integrated unit located at the windshield, eliminating the need for separate optical combiners and complex projection optics. This integration achieves large projection surfaces while simplifying the overall device structure and reducing space requirements.
Solution Approach 2:
The windshield serves multiple functions: it acts as both the display surface and the combiner, simultaneously providing structural support, optical reflection, and display functionality. This multi-functionality eliminates the need for dedicated separate components.
2Reliability
If display reflects visual scene through windshield, then virtual image is created at distance, but focus distance disparity occurs between virtual image and real-world environment
Solution Approach 1:
The system dynamically adjusts display parameters including focal distance and vergence to match the viewer's eye position and accommodation state. By changing these parameters in real-time based on tracking data, the system eliminates focus distance disparity and prevents visual fatigue.
Solution Approach 2:
The system uses eye tracking feedback to continuously monitor viewer position and adjust display parameters accordingly. This closed-loop control ensures the virtual image remains at a comfortable focus distance that matches the real-world environment.
3Reliability
If stereoscopic displays with additional glasses are utilized, then independent focus control is achieved, but obstructions within field of view are introduced
Solution Approach 1:
The patent extracts the focus control capability from physical glasses and implements it through software-based rendering and optical parameter adjustment in the display system itself. This eliminates the need for additional glasses while preserving independent focus control for each eye.
4Reliability
If projector-based approaches are used, then images can be projected, but larger space for projection optics is required resulting in narrow field of view
Solution Approach 1:
The display is merged directly with the windshield surface, eliminating the need for separate projection optics and mirrors. This integration enables wide field of view while maintaining effective image projection capability across the entire windshield area.
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 system provides a realistic and high-quality synthetic light field augmentation of the real-world environment, offering a comfortable viewing experience with depth perception and a wide field of view, suitable for automotive and other space-constrained environments.
Implementation Method 1
an optical combiner arranged on an optical path of the light field display unit and on an optical path of a real-world light field of a real-world environment... the optical combiner is employed to reflect a first part and a second part of the synthetic light field towards the first eye and the second eye
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
Tracking means (104) are utilised to determine a relative location of a first eye (124a, 202a, 312a, 416a, 422a, 504, 806a) and of a second eye (124b, 202b, 312b, 416b, 422b, 504, 806b) of user(s) (126) with respect to an optical combiner (108). An input (502) for a light field display unit (106, 302, 400, 804) is generated, based on the relative location of the first eye and of the second eye. The input is employed at the light field display unit to produce a synthetic light field (130), wherein the optical combiner is employed to reflect a first part and a second part of the synthetic light field towards the first eye and the second eye, respectively, whilst optically combining the first part and the second part of the synthetic light field with a real-world light field (112) of a real-world environment (102).