Optical Waveguide Virtual Image Projection With Variable Depth
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Solution Overview
Problem
Conventional head-up displays have a limited eyebox size, restricting viewer seating positions, and lack the ability to vary projection distances, making them less suitable for both classic and augmented reality applications.
Innovation Solution
A device incorporating an optical waveguide with a switchable holographic layer that adjusts projection distances, allowing for multiple image planes at different depths, including stereoscopic perception and augmented reality enhancements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an optical waveguide is used to expand the exit pupil, then the eyebox size is enlarged, but the projection distance becomes fixed and cannot be varied
Solution Approach 1:
The patent introduces a switchable holographic layer that can dynamically change the optical path within the waveguide, enabling the projection distance to be varied between near and far ranges while maintaining the expanded eyebox provided by the waveguide structure
Solution Approach 2:
The holographic layer acts as an intermediary element within the optical waveguide system, manipulating light propagation to create different virtual image distances without compromising the exit pupil expansion achieved by the waveguide
2Device complexity
If a fixed projection distance is used, then the device structure is simple, but the device cannot accommodate both classic and augmented reality applications
Solution Approach 1:
The switchable holographic layer provides dynamic reconfigurability, allowing the same device to adapt between classic display mode and augmented reality mode with different projection distances, thereby increasing application compatibility without requiring multiple separate systems
Solution Approach 2:
The optical waveguide with switchable holographic layer serves multiple functions: it expands the exit pupil for larger eyebox, enables variable projection distances, and supports both classic and augmented reality applications through a single integrated 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
Enables flexible projection distances and simultaneous display of information at various depths, enhancing user flexibility and compatibility with both classic and augmented reality applications.
Implementation Method 1
The light that is coupled into the optical waveguide and carries the image information undergoes total internal reflection at the interfaces thereof and is thus guided within the optical waveguide
Implementation Method 2
a first light-incidence-side diffraction grating that diffracts incident light to cause the diffracted light to enter the optical waveguide
Data Source
AI summary
A device for generating a virtual image. The device has at least one image-generating unit for producing an image and an optical waveguide for expanding an exit pupil. The optical waveguide has an output coupling region. An optical element for influencing a projection distance for at least a partial region of the virtual image is arranged adjacent to the output coupling region.