Substrate Guided Relay With Multiple Output Couplers
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Solution Overview
Problem
Substrate-guided optical image relays face limitations in achieving a wide horizontal field of view due to the fundamental constraints imposed by the angle of total internal reflection and the angular information maintenance during light propagation, which restricts the image reproduction and viewing experience.
Innovation Solution
The implementation of multiple output couplers with different projection angles and individually selectable light valves, allowing for sequential operation and control of light transmission to achieve a wider field of view, with the use of liquid crystal material and polarized light management to optimize light routing and alignment with the eyebox.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single output coupler is used in a substrate-guided optical image relay, then the device complexity is reduced, but the horizontal field of view is limited by the angle of total internal reflection
Solution Approach 1:
The patent divides the single output coupler function into multiple output couplers (first, second, and third output couplers) with different projection angles. Each output coupler is positioned at different locations on the substrate and oriented at different angles to guide light to different horizontal fields of view, thereby achieving a wide field of view without requiring complex adjustable mechanisms in each coupler
Solution Approach 2:
The patent employs light valves positioned between the image source and output couplers that can dynamically switch between different operational states. These light valves enable sequential operation where different portions of the image are directed to different output couplers based on the desired field of view, providing dynamic adaptability while maintaining relatively simple static coupler structures
2Adaptability or versatility
If multiple output couplers with different projection angles are used to achieve wide field of view, then the horizontal field of view is enhanced, but the optical complexity and alignment requirements increase
Solution Approach 1:
Each output coupler is designed with specific local properties - different projection angles and positions - optimized for its particular function in the wide field of view system. The first output coupler has a first projection angle for a first horizontal field of view portion, the second output coupler has a second projection angle for a second horizontal field of view portion, and the third output coupler has a third projection angle for a third horizontal field of view portion
Solution Approach 2:
The system employs sequential operation where light valves switch between different operational states to direct different portions of the image to different output couplers in a periodic or time-sequential manner. This allows the complex multi-coupler system to be controlled through periodic switching rather than requiring all couplers to be simultaneously active and precisely aligned
3Volume of moving object
If light is propagated through the substrate to guide image rays, then the form factor is reduced, but the angular information is maintained which restricts image reproduction
Solution Approach 1:
The patent adds the dimension of multiple projection angles by positioning output couplers at different locations and orientations on the substrate. Instead of relying on a single angle of projection, the system uses spatial distribution of multiple couplers with different angular characteristics, thereby breaking the constraint that substrate-guided relays must maintain angular information while achieving wide field of view and improved image reproduction
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 configuration enhances the horizontal field of view to 120 degrees or more, providing a seamless and efficient image reproduction experience by integrating image portions over time, improving uniformity and reducing optical complexity, while maintaining high eyebox light efficiency.
Implementation Method 1
the fundamental constraints imposed by the angle of total internal reflection and the angular information maintenance during light propagation
Data Source
AI summary
A substrate guided relay includes multiple output couplers and multiple light valves positioned between the substrate and the output couplers. The number of light valves may be equal to the number of output couplers, or may be more or less than the number of output couplers. The light valves may be enabled sequentially, or may be enabled based on the position of a user's eye. The light valves may include liquid crystal material.