Adjustable IPD Waveguide Translation for AR Eyebox Power Savings
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Solution Overview
Problem
Conventional diffractive display systems waste light power by providing an expanded eyebox larger than necessary for each user, leading to reduced battery life and excess heat generation.
Innovation Solution
The translational movement of waveguide plates relative to the light projection system allows for a reduced expanded eyebox size that accommodates different interpupillary distances, optimizing light power usage and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the expanded eyebox is made larger to accommodate different IPDs, then adaptability is improved, but light power is wasted and battery life is reduced
Solution Approach 1:
The patent implements a movable waveguide plate that can translate along the optical axis relative to the projection system. This dynamic adjustment allows the eyebox size to be optimized for each user's specific IPD, preventing light waste while maintaining adaptability across different users. The translation mechanism enables the system to dynamically reconfigure the optical path based on individual user requirements.
2Adaptability or versatility
If the expanded eyebox is made larger to accommodate different IPDs, then adaptability is improved, but heat generation increases
Solution Approach 1:
By enabling the waveguide plate to translate dynamically, the system can minimize the eyebox size to match each user's specific IPD. This prevents excess light from being expanded into unnecessary areas, thereby reducing the energy waste that would otherwise be converted into heat. The dynamic configuration ensures heat generation is minimized while maintaining full adaptability.
3Use of energy by moving object
If the waveguide plate is made movable to reduce eyebox size, then light power usage is improved, but device complexity increases
Solution Approach 1:
The patent employs a translation assembly with a movable stage that carries the waveguide plate along the optical axis. This mechanical dynamic system allows precise control of the eyebox size to match user IPD, optimizing light power usage. The added complexity is localized to the translation mechanism, while the overall system architecture remains relatively simple.
Solution Approach 2:
The patent changes the positional parameter of the waveguide plate relative to the projection system. By adjusting this single parameter (the distance along the optical axis), the system optimizes light power usage for different IPDs. This parameter-based approach simplifies the control mechanism compared to more complex adaptive systems.
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 enhances battery life and reduces heat generation by using less light power while maintaining a full augmented reality experience across the relevant eyebox region.
Implementation Method 1
diffractive display systems, which comprise transparent display elements through which light for forming images is projected
Implementation Method 2
a light projection system (e.g., including one or more light sources and one or more microelectromechanical system mirrors) that projects light toward the set of transparent plates
Data Source
AI summary
A display system may include a waveguide plate comprising opposing parallel surfaces, an in-coupling grating, an expansion grating, and an out-coupling grating. The display system may include a projection system configured to direct input light toward the in-coupling grating and a translation assembly configured to translate the waveguide plate relative to the projection system along an axis. The in-coupling grating may be configured to diffract the input light to cause total internal reflection of the input light within the waveguide plate. The expansion grating may be configured to (i) cause replica expansion of the input light and (ii) cause the input light to propagate within the waveguide plate toward the out-coupling grating. The out-coupling grating may be configured to (i) cause replica expansion of the input light replica expanded by the expansion grating and (ii) diffract the input light replica expanded by the expansion grating outward from the waveguide plate.