Reflective Display Panel for Waveguide Gaze Tracking
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Solution Overview
Problem
Designing virtual and augmented reality headsets with near-eye displays that are aesthetically pleasing, energy-efficient, and exhibit optimal optical performance is challenging due to component bulkiness and power consumption issues.
Innovation Solution
The implementation of a head-mounted device with a display module comprising a waveguide, a reflective display panel operating in dual modes for image light modulation and infrared light reflection, an infrared image sensor, and control circuitry for gaze tracking and optical alignment, along with a time multiplexing scheme to prevent interference between image and world-facing camera operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective display panel is used to modulate image light, then image display quality is improved, but the device bulkiness increases
Solution Approach 1:
The infrared image sensor is positioned within the display module housing, nested alongside the reflective display panel and illumination optics. This nested arrangement allows the imaging components to occupy space that would otherwise be unused, reducing overall device bulkiness while maintaining full image display functionality.
Solution Approach 2:
The display module is designed to serve multiple functions: it acts as both the image display component and the housing for the infrared image sensor. This multi-functional design eliminates the need for separate dedicated imaging components, thereby reducing device volume while maintaining high image display quality.
2Adaptability or versatility
If dual operating modes are implemented for the reflective display panel, then functional versatility is improved, but device complexity increases
Solution Approach 1:
The reflective display panel is designed with dynamic switching capability between two operating modes: image modulation mode and infrared reflection mode. This dynamic adaptability allows a single component to serve multiple functions, enhancing functional versatility while the integrated control circuitry manages the switching complexity internally.
Solution Approach 2:
The reflective display panel serves as a universal component that can either modulate image light for display or reflect infrared light for imaging operations. This multi-functionality is achieved through integrated control circuitry that switches the panel's operation based on the required function, thereby enhancing versatility while containing complexity within the integrated system.
3Reliability
If time multiplexing is used to prevent interference between display and camera operations, then operational reliability is improved, but processing time increases
Solution Approach 1:
The system implements periodic time multiplexing where the reflective display panel alternates between image modulation operations and infrared reflection operations in regular cycles. This periodic switching ensures reliable operation by preventing interference between display and imaging functions, while the rhythm of the cycling is optimized to minimize total processing time.
Solution Approach 2:
The time multiplexing scheme is designed to maintain continuous useful action by rapidly switching between display and imaging modes within each frame period. The brief transition times between modes are minimized, ensuring that the system maintains high operational reliability while the total time loss from multiplexing is kept to a minimum through efficient timing.
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 minimizes bulkiness, optimizes power usage, and enhances optical performance by enabling efficient image display and gaze tracking while preventing interference between display and camera operations, providing a seamless user experience.
Implementation Method 1
the reflective display panel may generate image light by modulating image data onto illumination light produced by the illumination optics
Implementation Method 2
the reflective display panel may reflect infrared light from the waveguide towards the infrared image sensor
Implementation Method 3
The waveguide may have an input coupler configured to couple image light into the waveguide. The waveguide may have an output coupler configured to couple the image light out of the waveguide and towards an eye box
Implementation Method 4
A partially reflective coating may be layered onto the reflective surface. The partially reflective coating may pass infrared wavelengths while reflecting visible wavelengths
Implementation Method 5
The infrared image sensor may gather infrared image sensor data based on the infrared light. The infrared light may be a version of the additional infrared light that has reflected off of an object external to the display such as a user's eye
Data Source
AI summary
A display may include a reflective display panel, an infrared image sensor and a waveguide. The panel may be operated in a first operating mode in which the panel reflects image light towards the waveguide and a second operating mode in which the panel reflects infrared light from the waveguide towards the infrared image sensor. The panel may also reflect infrared light from an infrared emitter towards the waveguide. If desired, the infrared image sensor may be mounted adjacent a reflective surface of a reflective input coupling prism on the waveguide. The infrared image sensor may receive the infrared light through the reflective surface. If desired, a world-facing camera may receive world light through the waveguide. The display module and the world-facing camera may be operated using a time multiplexing scheme to prevent the image light from interfering with images captured by the world-facing camera.