HUD Waveguide Diffraction Layout for Complete Virtual Images
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Solution Overview
Problem
Existing head-up display systems suffer from partial image missing and inefficient utilization of luminous fluxes due to angular variations in incident light, and there is a demand for higher luminance in displayed images.
Innovation Solution
An optical system with a first expansion region that splits and duplicates luminous fluxes in one direction and a second expansion region that further splits and duplicates them in a perpendicular direction, where the first expansion region has a central region with a diffracted light quantity greater than the end regions, optimizing the diffraction efficiency to prevent partial image missing and improve luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a waveguide with diffractive optical element is used to expand exit pupil, then the exit pupil can be expanded in two directions, but angular variation in incident luminous flux causes partial image missing and reduces luminance efficiency
Solution Approach 1:
The waveguide is divided into multiple functional regions: a first expansion region with a diffraction grating for expanding luminous flux in a first direction, and a second expansion region with a different diffraction grating for expanding in a second direction. This segmentation allows each region to be optimized independently for its specific expansion direction, preventing image loss while maintaining angular variation tolerance.
Solution Approach 2:
Different regions of the waveguide are assigned different diffraction grating configurations with specific orientations and parameters. The first expansion region has gratings optimized for horizontal expansion while the second expansion region has gratings optimized for vertical expansion. This local differentiation ensures that each region contributes effectively to image completeness without causing partial image missing.
2Quantity of substance
If diffractive optical elements are used to expand luminous flux, then exit pupil is increased, but utilization efficiency of luminous flux decreases due to angular variations
Solution Approach 1:
The system dynamically adapts to angular variations in incident luminous flux by using multiple expansion regions with different diffraction grating orientations. As the angle of incident light changes, different regions of the waveguide become more or less effective, but the combined effect of all regions ensures continuous efficient utilization of luminous flux across a range of angles, preventing efficiency loss.
Solution Approach 2:
The diffraction grating parameters (orientation, period, depth) are changed across different regions of the waveguide to optimize performance for different incident angles. By varying these parameters spatially, the system maintains high luminous flux utilization efficiency even when the angle of incident light varies, preventing energy loss.
3Device complexity
If uniform diffraction is applied across the entire waveguide, then expansion is simplified, but end regions cause image loss and reduce overall system performance
Solution Approach 1:
The waveguide is segmented into distinct expansion regions with different diffraction grating configurations. The first expansion region uses gratings oriented for horizontal expansion while the second expansion region uses gratings oriented for vertical expansion. This segmentation prevents image loss at boundaries while maintaining manageable system complexity through modular design.
Solution Approach 2:
The diffraction grating configurations are made asymmetric across different regions rather than uniform throughout. The first expansion region has gratings with specific orientation and parameters optimized for one direction, while the second expansion region has differently oriented gratings optimized for the perpendicular direction. This asymmetric design prevents image loss while keeping the overall system relatively simple.
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 effectively prevents partial image missing and enhances the utilization of luminous fluxes, ensuring a complete and properly luminated virtual image is displayed to the observer, even with angular variations in incident light.
Implementation Method 1
a first expansion region that expands a luminous flux traveling in a first direction by splitting and duplicating it into luminous fluxes traveling in a second direction intersecting the first direction
Implementation Method 2
a second expansion region that expands the luminous fluxes traveling in the second direction by splitting and duplicating them to increase the number of luminous fluxes
Implementation Method 3
a light-transmitting member that reflects a luminous flux emitted from the optical system, the image as a virtual image being displayed superimposed on a real scene visible through the light-transmitting member
Data Source
AI summary
An optical system includes a first expansion region that expands a luminous flux traveling in a first direction by splitting and duplicating it into luminous fluxes traveling in a second direction intersecting the first direction to increase the number of luminous fluxes, and a second expansion region that expands the luminous fluxes traveling in the second direction by splitting and duplicating them to increase the number of luminous fluxes. The first expansion region has a central region that contains a center of the first expansion region, and an end region that lies on at least one end side of the first expansion region. The end region has a diffracted light quantity less than half the diffracted light quantity in the central region.