Shutter Eyewear for Head-Up Displays
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Solution Overview
Problem
Traditional head-up displays (HUDs) in the aerospace industry rely on sophisticated optics to meet performance requirements, which can be bulky, costly, and inefficient, and existing solutions do not effectively address the need for high transmittance in avionic environments.
Innovation Solution
A conformal-capable head-up display system using shutter eyewear with dual, crossed dichroic guest-host liquid crystal display (LCD) light shutters, which alternately project pre-distorted images for each eye, reducing the need for precise angular control and allowing high transmittance by controlling image visibility through temporal multiplexing and active pre-distortion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sophisticated optics are used in HUDs, then performance requirements for angular control and uniformity are met, but the system becomes bulky, heavy, and costly
Solution Approach 1:
The patent replaces traditional mechanical optical systems with liquid crystal technology. The liquid crystal shutter assembly uses electro-optic effects rather than complex mechanical optics to achieve the same image projection and control functions, eliminating bulky lenses and mirrors while maintaining angular control precision
Solution Approach 2:
The patent changes the operational parameters of the display system by using liquid crystal materials that can rapidly switch between transparent and opaque states when voltage is applied. This allows for precise control of light transmission without requiring sophisticated optical pathways, thereby reducing system weight while maintaining performance
2Reliability
If traditional sophisticated optics are used in HUDs, then performance requirements for angular control and uniformity are met, but the system becomes costly
Solution Approach 1:
The patent replaces expensive precision optical components with more cost-effective liquid crystal technology. The liquid crystal shutter assembly can be manufactured using standard semiconductor fabrication processes rather than requiring precision optical machining, significantly reducing manufacturing costs while maintaining angular control precision
Solution Approach 2:
The patent employs liquid crystal materials and components that are inherently less expensive than traditional optical elements. These liquid crystal assemblies can be replaced more easily and at lower cost than precision optics, making the overall system more cost-effective
3Illumination intensity
If liquid crystal shutters are used to control image visibility, then high transmittance is achieved, but temporal multiplexing is required
Solution Approach 1:
The patent uses periodic switching of the liquid crystal shutters at frequencies above human perception thresholds. The shutters open and close in rapid succession for each eye, creating the illusion of simultaneous viewing while actually using temporal multiplexing. This periodic action maintains high average transmittance while enabling stereoscopic display
Solution Approach 2:
The patent maintains continuous display output by rapidly alternating between left and right eye images. The liquid crystal shutters switch so quickly that the human visual system perceives continuous imagery, eliminating the need for mechanical synchronization mechanisms while achieving high transmittance through the liquid crystal material
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 high transmittance and simplified optical requirements, enabling the use of compact and low-cost optics while minimizing vergence errors and accommodating non-ideal windscreen distortions, thus providing effective and efficient HUD functionality in avionic environments.
Implementation Method 1
a liquid crystal cell having a contrast ratio in a range from about 200 to about 400
Implementation Method 2
a pi cell stacked between two polarizers
Implementation Method 3
dual, crossed dichroic guest-host liquid crystal display (LCD) light shutters
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A system and method of displaying a conformal-capable head-up display image is provided. Distortions caused by combiner curvature, for example, are removed by pre-distorting and projecting separate images for each eye.Shutter-based eyewear controls the visibility as the imagery is cycled, e.g., shuttered, between left and right eyes. The combined image generator, projector and eyewear system maintains minimal vergence errors, minimal dipvergence errors, acceptable average transmittance, and optionally, high conformality.