Waveguide Combiner Glare Mitigation for Tactical Aircraft HUDs
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Solution Overview
Problem
Conventional Head-Up Displays (HUDs) are large, expensive, and difficult to fit in small aircraft, and they are susceptible to glare and sunspot imaging, especially in glass cockpit environments, which is a challenge for tactical aircraft with large area head-down displays.
Innovation Solution
A compact HUD system using a substrate waveguide combiner with input and output couplers and a glare mitigator, which includes a diffuser or active element to prevent glare by diffusing or blocking sunlight before it strikes the waveguide, allowing for reduced susceptibility to solar glare and sunspot imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a waveguide combiner is used to reduce HUD size, then the device complexity and size are reduced, but susceptibility to glare and sunspot imaging increases
Solution Approach 1:
A diffuser element is introduced as an intermediary component between the waveguide combiner and the pilot's eye. This diffuser scatters sunlight that enters the waveguide, preventing concentrated sunspots and glare from reaching the pilot while maintaining the compact waveguide structure.
Solution Approach 2:
The waveguide combiner is designed with spatially varying properties - the diffuser is positioned only in regions where sunlight enters the waveguide, while other regions maintain their original optical properties for normal HUD operation. This localized treatment reduces glare without affecting overall HUD performance.
2Adaptability or versatility
If conventional HUDs are used to provide display information, then display functionality is achieved, but the device is large and difficult to fit in small aircraft
Solution Approach 1:
The patent replaces the traditional mechanical lens-based optical system with a substrate waveguide combiner that uses total internal reflection and diffraction gratings to guide and display information. This substitution dramatically reduces the physical size while maintaining HUD functionality.
Solution Approach 2:
The waveguide combiner utilizes the thickness dimension of a flat substrate to achieve optical functions that traditionally required large volumetric lens systems. By guiding light through the substrate thickness via total internal reflection, the system achieves compact form factor while maintaining adequate field of view and eye box.
3Object-affected harmful factors
If a diffuser is added to reduce glare, then glare susceptibility is reduced, but the device complexity increases
Solution Approach 1:
The diffuser element is integrated with the waveguide combiner structure, either as a separate layer bonded to the combiner surface or as a patterned region within the combiner substrate itself. This merging approach reduces the number of discrete components and simplifies the overall system assembly.
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 HUD system provides a compact, glare-resistant display solution that is compatible with large area head-down displays, offering improved visibility and reduced sunspot brightness while maintaining an unobstructed view, suitable for tactical aircraft.
Implementation Method 1
The input coupler diffracts light from an image source into a waveguide
Implementation Method 2
The waveguide is transparent and allows viewing of an outside scene and diffracted light from the image source
Implementation Method 3
The output coupler diffracts light out of the waveguide towards a pilot's eye
Implementation Method 4
A diffuser may be disposed between a surface of the combiner and a windshield of the cockpit or between the surface of the combiner and a ceiling of the cockpit
Data Source
AI summary
A system and method for a head up display (HUD) can mitigate glare. The head up display can include a waveguide combiner including an input grating and an output grating and a glare mitigator disposed to prevent glare through the output grating from reaching an eye box. The glare mitigator can be a shade, a diffuser, a dimming element, or other device for mitigating glare. The glare mitigator can be an active or passive glare mitigator.