HUD Waveguide Periscopic Effect Eliminates Alignment Detector
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Solution Overview
Problem
Conventional Head-Up Displays (HUDs) require a Combiner Alignment Detector (CAD) to prevent misalignment errors, which adds cost, complexity, and reliability issues, and are not suitable for compact or less precise stow mechanisms.
Innovation Solution
A HUD system that uses a substrate waveguide with input and output diffraction gratings to achieve a periscopic effect, eliminating the need for a CAD and providing insensitivity to positional and angular errors, thereby reducing costs and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Combiner Alignment Detector (CAD) is used to prevent misalignment errors, then alignment precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the CAD component from the HUD system entirely. By using a substrate waveguide with integrated diffraction gratings, the alignment detection function is eliminated, achieving alignment precision through the inherent optical design rather than active detection mechanisms.
Solution Approach 2:
The substrate waveguide with diffraction gratings provides self-alignment through its optical design. The periscopic effect created by the gratings automatically maintains proper alignment without requiring external detection or correction systems, making the system self-correcting for alignment errors.
2Measurement precision
If a Combiner Alignment Detector (CAD) is used to prevent misalignment errors, then alignment precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the CAD component, removing the associated manufacturing costs for the detector, its mounting structure, and calibration procedures. The alignment function is achieved through the standard substrate waveguide fabrication process with integrated diffraction gratings.
Solution Approach 2:
The substrate waveguide with diffraction gratings provides a cost-effective alternative to expensive CAD systems. The gratings are fabricated using standard semiconductor manufacturing techniques, making the solution economically viable for mass production.
3Measurement precision
If a Combiner Alignment Detector (CAD) is used to prevent misalignment errors, then alignment precision is improved, but system reliability decreases
Solution Approach 1:
By removing the CAD component, the patent eliminates potential failure points associated with the detector, its electronics, and calibration mechanisms. The system becomes more reliable as it no longer depends on active alignment detection and correction systems.
Solution Approach 2:
The substrate waveguide with diffraction gratings provides inherent alignment stability through its optical design. The periscopic effect automatically compensates for misalignments, making the system more reliable by eliminating components that could fail.
4Device complexity
If a substrate waveguide with diffraction gratings is used to achieve periscopic effect, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent integrates the diffraction gratings directly into the substrate waveguide structure, combining multiple functions into a single component. This reduces overall device complexity while the gratings are fabricated using standard semiconductor manufacturing processes that can achieve required precision.
Solution Approach 2:
The diffraction grating design parameters (period, depth, shape) are optimized to achieve the desired periscopic effect while being compatible with standard manufacturing capabilities. By carefully selecting grating parameters, the system achieves high performance without requiring ultra-precision manufacturing beyond standard industrial capabilities.
5Ease of operation
If the combiner is moved to and from operational and stowed positions using a less precise stow mechanism, then ease of operation is improved, but alignment precision deteriorates
Solution Approach 1:
The substrate waveguide with diffraction gratings provides self-alignment through the periscopic effect. As the combiner moves between positions, the grating design automatically compensates for positional variations, maintaining alignment precision without requiring a high-precision stow mechanism.
Solution Approach 2:
The diffraction grating parameters are designed to provide tolerance to positional and angular variations. By optimizing the grating geometry and period, the system maintains stable image display across six degrees of freedom, allowing use of less precise but more operationally convenient stow mechanisms.
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 achieves stable image display across six degrees of freedom without the need for a CAD, even with less precise stow mechanisms, resulting in a compact, lightweight, and cost-effective HUD with reduced alignment errors.
Implementation Method 1
The collimated light travels from the input to the output within the substrate waveguide by total internal reflection
Implementation Method 2
An input diffraction grating is disposed in a first area at the input, and an output diffraction grating is disposed in a second area at the output. The second diffraction grating is parallel with respect to the first diffraction grating or perpendicular to the first diffraction grating. The second diffraction grating is matched to the first diffraction grating to achieve a periscopic effect.
Data Source
AI summary
A display can be utilized with an image source. The display includes a collimator and a substrate waveguide. The substrate waveguide sees collimated light from the collimator at an input and provides the collimated light to an output. The collimated light travels from the input to the output within the substrate by total internal reflection. An input diffraction grating is disposed in a first area at the input and an output diffraction grating is disposed in a second area at the output. The second diffraction grating is matched to the first diffraction grating. A combiner alignment detector is not required due to the periscopic effect according to one embodiment.