Head-Up Display Eye-Tracking Fallback for Stable Virtual Image Depth
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Solution Overview
Problem
Eye-tracking systems in head-up displays can be unreliable, particularly when displaying multiple plane or 3D content with finite virtual image depths, leading to inconsistent image quality and potential safety issues due to loss of confidence in eye position measurements.
Innovation Solution
A display system that uses eye-tracking to determine user positions within an eye-box, adjusting virtual image distances based on confidence levels, and employing holographic projectors with spatial light modulators to compute bespoke holograms for accurate light delivery and windshield compensation, ensuring continuous image quality even when eye-tracking confidence is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If eye-tracking is used to determine precise eye position for multi-plane or 3D content display, then image quality and viewing experience are improved, but system reliability deteriorates due to unreliable eye position measurements
Solution Approach 1:
The system dynamically adjusts the virtual image distance based on the reliability of eye-tracking measurements. When confidence in eye position is high, the system displays content at finite virtual image distances optimized for multi-plane or 3D effects. When confidence drops below a threshold, the system transitions to projecting at infinite virtual image distance, which is less sensitive to eye position accuracy. This dynamic adaptation resolves the contradiction by making the display system's behavior flexible rather than fixed, allowing it to maintain reliability across varying measurement conditions.
2Measurement precision
If finite virtual image distances are used for multi-plane or 3D content, then viewing experience and image quality are improved, but sensitivity to eye position errors increases
Solution Approach 1:
The system changes the virtual image distance parameter based on eye-tracking confidence levels. At high confidence, finite virtual image distances are used to enable multi-plane or 3D content with superior image quality. At low confidence, the parameter is changed to infinite virtual image distance, which reduces sensitivity to eye position errors. This parameter adaptation allows the system to optimize between image quality and robustness against measurement errors.
3Reliability
If eye-tracking confidence is low, then safety-critical information delivery may be compromised, but switching to infinite virtual image distance maintains continuous viewing experience
Solution Approach 1:
The system introduces virtual image distance as an intermediary parameter that mediates between eye-tracking reliability and viewing experience continuity. When eye-tracking confidence is low, adjusting the virtual image distance to infinity acts as a compensatory mechanism that maintains acceptable viewing experience while the system potentially alerts the user or adjusts other parameters to ensure safety-critical information is still delivered. This intermediary adjustment prevents complete system failure and maintains operational continuity.
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
Ensures a continuous viewing experience for drivers by maintaining image quality and safety-critical information delivery, even when eye-tracking confidence is below a threshold, by projecting at infinite virtual image distances and using eye-box position data for hologram calculation and light control.
Implementation Method 1
a waveguide pupil expander arranged to expand an exit pupil of the display system
Implementation Method 2
Light modulation may be achieved using electrically-addressable liquid crystals, optically-addressable liquid crystals or micro-mirrors
Implementation Method 3
Light scattered from an object contains both amplitude and phase information. This amplitude and phase information can be captured on, for example, a photosensitive plate by well-known interference techniques to form a holographic recording, or 'hologram'
Implementation Method 4
The waveguide pupil expander is arranged to expand an exit pupil of the display system
Data Source
AI summary
Disclosed embodiments include a display system comprising an eye-box from which virtual images formed by the display system are visible. In some embodiments, the display system includes an image projector arranged to project a virtual image at a virtual image distance from the eye-box, and a user-tracking system arranged to determine an eye-box position of a user within the eye-box and a confidence value associated with the determined eye-box position. In some embodiments, the image projector is arranged to (i) project the virtual image at a finite virtual image distance after determining that the confidence value is above a threshold value and (ii) project the virtual image at an infinite virtual image distance after determining that the confidence value is below the threshold value.