Waveguide-Based Projector for Head-Up Display Eyebox Expansion
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Solution Overview
Problem
Existing projector-based head-up display (HUD) systems face challenges in achieving a sufficiently large eyebox due to the small etendue of microdisplays, leading to unreliable positioning of both eyes within the eyebox. Additionally, diffuser screens used to expand etendue suffer from backscattering, image blurring, and potential damage from concentrated sunlight.
Innovation Solution
The proposed solution involves a waveguide-based projector device that omits diffuser screens and instead uses an optical waveguide within a network of lenses to expand etendue and enlarge the eyebox. The waveguide captures and replicates light to create an expanded pupil, functioning as an etendue expander without the drawbacks of diffuser screens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If diffuser screens are used to expand etendue, then the eyebox size increases, but backscattering and image blurring occur
Solution Approach 1:
The patent removes the diffuser screen from the optical system entirely, replacing it with a waveguide-based etendue expansion mechanism. This extraction of the problematic component eliminates backscattering and image blurring while maintaining the eyebox expansion function through alternative means (waveguide geometry and optical elements).
Solution Approach 2:
The patent introduces a waveguide as an intermediary component between the microdisplay and the output optics. The waveguide serves as a mediator that expands etendue through its geometric structure and optical properties without requiring a diffuser screen, thereby avoiding the harmful backscattering effects while achieving the desired eyebox enlargement.
2Area of stationary object
If diffuser screens are used to expand etendue, then the eyebox size increases, but the system becomes vulnerable to sunlight concentration damage
Solution Approach 1:
By removing the diffuser screen from the system, the patent eliminates the component that concentrates and reflects sunlight, thereby removing the vulnerability to solar damage while preserving the etendue expansion capability through the waveguide architecture.
Solution Approach 2:
The patent converts the harmful concentration of sunlight on diffuser screens into a beneficial distributed light path through the waveguide. The waveguide's optical structure disperses and guides light away from concentrated solar hot spots, transforming a potential damage mechanism into a protective light distribution system.
3Area of stationary object
If microdisplay etendue is small, then the system remains compact, but the eyebox size becomes insufficient for reliable eye positioning
Solution Approach 1:
The patent employs the waveguide to expand etendue by utilizing optical path length and geometric dispersion in additional dimensional spaces. The waveguide's extended structure and internal optical pathways create effective etendue expansion without requiring a proportionally larger microdisplay area, thereby maintaining system compactness while achieving sufficient eyebox size.
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
This approach effectively enlarges the eyebox to accommodate both eyes simultaneously, eliminates the backscattering and image blurring issues associated with diffuser screens, and reduces the risk of damage from sunlight concentration, while also optimizing manufacturing costs and compatibility with various projection technologies.
Implementation Method 1
an optical waveguide within a network of lenses to expand etendue and enlarge the eyebox. The waveguide captures and replicates light to create an expanded pupil
Implementation Method 2
The waveguide captures and replicates light to create an expanded pupil, functioning as an etendue expander
Implementation Method 3
a first set of lenses optically coupled to the first port and a second set of lenses optically coupled to the second port
Implementation Method 4
The first set of lenses optically coupled to the first port and a second set of lenses optically coupled to the second port
Data Source
AI summary
In examples, a device comprises an optical waveguide and first and second ports on the optical waveguide, the second port larger than the first port. The device also comprises a first set of lenses optically coupled to the first port and a second set of lenses optically coupled to the second port.