Head-Up Display Waveguide Layout for Wider Multi-Depth Field of View
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Solution Overview
Problem
Existing image projectors, particularly head-up displays, face challenges in expanding the field of view due to the limited range of angles of light rays that can propagate through the eye's pupil, resulting in a small and position-dependent visible image area, which complicates integration into vehicles.
Innovation Solution
The use of a pupil expander, such as a waveguide, to increase the range of angles of light rays that can propagate through the eye's pupil, allowing for simultaneous formation of near-field and far-field images without additional clearance volume, achieved by optimizing the field of view through holographic projection techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spatial light modulator is used for image projection, then the device can generate virtual images, but the diffraction angle is limited which restricts the field of view
Solution Approach 1:
The patent divides the image projection into multiple discrete angular channels using diffraction gratings. Each grating segment directs light at a specific angle, creating multiple virtual images at different positions. This segmentation allows the system to achieve a wide overall field of view by combining multiple narrow angular channels, resolving the contradiction between limited diffraction angle and required field of view.
Solution Approach 2:
The patent transitions from a single-plane image projection to a multi-plane configuration where virtual images are formed at different distances (near-field and far-field planes). By adding the dimensional parameter of image distance, the system expands the effective field of view without requiring a larger diffraction angle from the spatial light modulator.
2Area of moving object
If the field of view is expanded to improve visibility, then more angular ranges can be seen, but the clearance space required increases significantly
Solution Approach 1:
The patent implements a nested configuration where multiple virtual image planes are positioned within the same physical clearance volume. The near-field and far-field image planes are arranged such that their light paths overlap spatially, allowing the system to provide multiple fields of view without proportionally increasing the required clearance space. This nesting approach resolves the contradiction by making the volume requirement grow slower than the field of view expansion.
3Adaptability or versatility
If multiple virtual images are formed at different distances, then near-field and far-field images can be displayed simultaneously, but the system complexity increases
Solution Approach 1:
The patent makes the spatial light modulator and diffraction grating system multi-functional by enabling them to generate virtual images at multiple distances simultaneously using the same hardware components. By controlling the holographic content and grating parameters, the system can adaptively switch between near-field and far-field image formation or display both concurrently, achieving versatility without adding separate projection systems for each distance.
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
Enhances the field of view in head-up displays by enabling simultaneous formation of near-field and far-field images without increasing the required clearance volume, allowing for more flexible integration into vehicle dashboards.
Implementation Method 1
a pupil expander, such as a waveguide, to increase the range of angles of light rays that can propagate through the eye's pupil
Implementation Method 2
The spatial light modulator may be reflective meaning that modulated light is output in reflection. The spatial light modulator may equally be transmissive meaning that modulated light is output in transmission.
Data Source
AI summary
Systems and methods disclosed herein include, among other aspects, a head-up display comprising an eye-box having a first dimension and a second dimension, where the head-up display is arranged to form first image content in a first image area at a first image area distance from the eye-box and second image content in a second image area at a second image area distance from the eye-box, where the first image area distance is less than the second image area distance and the first image area is at least partially overlapping in the first dimension with the second image area, and where the second image area extends less far in angular space than the first image area in at least one direction of the first dimension.