Compact HUD Waveguide Combining Light Pipe and Turning Grating
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Solution Overview
Problem
Conventional Head-Up Displays (HUDs) are large, expensive, and difficult to fit into smaller aircraft due to their reliance on large optical components, which also increase size, weight, and complexity, leading to reduced brightness and contrast, and are costly for smaller aircraft.
Innovation Solution
A compact HUD system utilizing a catadioptric optical system with a polarizing beam splitter, field lens with diffractive surface, and a waveguide combiner, which includes a turning grating or mirror array to expand the pupil, reducing the need for expensive corrector lenses and minimizing package size while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional HUDs use large optical components to form adequate field of view and viewing eye box, then the field of view and eye box are sufficient, but the volume and weight of the package become too large to fit within the constrained space in the cockpit of smaller aircraft
Solution Approach 1:
The patent combines multiple optical functions (collimation, field of view expansion, eye box formation) into a single integrated waveguide component. The waveguide incorporates diffraction gratings that simultaneously perform pupil expansion and field of view control, eliminating the need for separate lenses, mirrors, and prisms found in conventional HUDs.
Solution Approach 2:
The patent uses diffraction gratings with specific periodic structures to change the optical parameters of light propagation. By controlling the grating period, orientation, and depth, the system transforms the spatial distribution of light to achieve both adequate field of view and compact packaging without requiring large optical components.
2Reliability
If conventional HUDs use large optical components including lenses, prisms, and mirrors, then adequate optical performance is achieved, but the cost becomes too expensive for smaller aircraft
Solution Approach 1:
The patent extracts the essential optical functions from the complex assembly of conventional HUD components and implements them through a single waveguide with diffractive structures. This eliminates expensive precision-machined optical components while maintaining the necessary optical performance through programmable diffraction patterns.
Solution Approach 2:
The patent replaces mechanical optical components (lenses, mirrors, prisms) with a diffractive optical system based on diffraction gratings. This substitution uses wave optics principles rather than geometric optics, enabling compact integration and reduced manufacturing costs while maintaining or improving optical performance.
3Area of stationary object
If conventional HUDs use folded optical paths with multiple components, then the field of view is expanded, but the package size increases due to additional optical components
Solution Approach 1:
The patent merges multiple optical components into a single waveguide structure. The waveguide simultaneously performs collimation, beam steering, and field of view expansion that would traditionally require separate lenses, mirrors, and prisms arranged in folded optical paths.
Solution Approach 2:
The patent transitions from planar folded optical paths to three-dimensional light propagation within the waveguide. By using diffraction gratings that operate in multiple dimensions, the system achieves expanded field of view without the need for folded paths, reducing the number of components and simplifying the overall device structure.
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 solution enables a compact, cost-effective HUD system with improved brightness and contrast, suitable for smaller aircraft, providing a wide field of view and efficient polarization management, while reducing size and weight, and maintaining high optical efficiency.
Implementation Method 1
a light pipe configured to expand a pupil in a first direction
Implementation Method 2
which includes a turning grating or mirror array to expand the pupil
Implementation Method 3
A compact HUD system utilizing a catadioptric optical system with a polarizing beam splitter
Implementation Method 4
field lens with diffractive surface
Data Source
AI summary
A head up display can be used in compact environments. The head up display includes a combiner system including at least one light pipe and a waveguide. The at least one light pipe includes a turning grating or mirror array for providing light into the waveguide from the light pipe. An additional light pipe can also be provided. The combiner system can be headworn or stand-alone and can provide dual axis pupil expansion.