Single DMD SLM for AR Mutual Occlusion
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Solution Overview
Problem
Existing Head-Mounted Display (HMD) systems for Augmented Reality (AR) face challenges in achieving mutual occlusion with increased complexity, cost, and power consumption due to the use of cascaded Spatial Light Modulators (SLMs) for occlusion mask generation and virtual content introduction.
Innovation Solution
A single Digital Light Processing (DLP) based Digital Micro-Mirror Device (DMD) SLM is used for both occlusion mask generation and introducing virtual digital content, reducing complexity and power consumption while enabling high-speed Pulse Width Modulation and spatial multiplexing, thereby achieving hard-edge occlusion with reduced cost and increased optical-see-through efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cascaded SLMs are used for occlusion mask generation and virtual content introduction, then mutual occlusion capability is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines the functions of occlusion mask generation and virtual content introduction into a single SLM device. The SLM displays a composite image that includes both the occlusion mask and virtual content, eliminating the need for cascaded SLM configurations and reducing overall device complexity while maintaining mutual occlusion capability.
Solution Approach 2:
The single SLM is designed to perform multiple functions simultaneously: generating the occlusion mask, introducing virtual digital content, and enabling hard-edge occlusion. This multi-functional approach replaces the specialized分工 of multiple SLMs, reducing complexity while preserving all necessary capabilities.
2Adaptability or versatility
If cascaded SLMs are used for occlusion mask generation and virtual content introduction, then mutual occlusion capability is achieved, but power consumption increases
Solution Approach 1:
The patent merges the operations of two SLMs into a single SLM, thereby halving the power consumption associated with SLM operation. The single SLM is driven to display the composite image containing both occlusion and virtual content, eliminating the need to power two separate display modules.
3Adaptability or versatility
If cascaded SLMs are used for occlusion mask generation and virtual content introduction, then mutual occlusion capability is achieved, but optical-see-through efficiency decreases
Solution Approach 1:
The patent combines the optical paths for occlusion and virtual content through a single SLM, eliminating the light loss that occurs when light passes through multiple SLMs in cascade. This single-pass configuration preserves more ambient light, thereby improving optical-see-through efficiency while still achieving hard-edge occlusion.
4Device complexity
If a single SLM is used for both occlusion mask generation and virtual content introduction, then device complexity and cost are reduced, but achieving hard-edge occlusion becomes more difficult
Solution Approach 1:
The patent applies local quality by treating different regions of the SLM display with different processing. The occlusion mask regions are processed to achieve sharp, hard edges through precise binary control, while virtual content regions maintain their visual quality. This localized processing ensures hard-edge occlusion is achieved in critical areas without compromising overall image quality.
Solution Approach 2:
The patent employs temporal multiplexing where the SLM rapidly switches between displaying the occlusion mask and virtual content at different time intervals. This periodic action allows the system to achieve hard-edge occlusion when needed while maintaining virtual content display, with the rapid switching being imperceptible to the human eye.
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
The solution significantly reduces the complexity and cost of the display optics assembly by approximately 50% and lowers power consumption, while enabling effective hard-edge occlusion and high optical-see-through efficiency, allowing for a more compact and efficient AR display system.
Implementation Method 1
The binary switchable DMD SLM has been utilized to its full potential by exploiting its inherent benefits... Binary-stable switching tilt angles enabling Spatial multiplexing
Implementation Method 2
High speed in the micro-seconds regime enabling completely digital Pulse Width Modulation (PWM)
Data Source
AI summary
A display method and system includes a module that intercepts the lightfield from an ambient Real World Scene in an observer's direct line-of-sight, 102, and then routes it through a spatial light modulator where the Scene forms an image. During a first portion of the frame time, selective pixels corresponding to the real world scene image on the SLM are modulated for their transparency or opacity and routed to the observer's eye. In a second portion of the frame time, a Digital computer generated Virtual image is created by spatially multiplexing a second illuminant on the same SLM and then routing it to the observer's eye. The resultant time-averaged image, as perceived by the observer, has the Real World Scene modulated for both its Transparency/opacity and also blended with computer generated Digital Virtual image. The present invention enables the ability to per-pixel hide or occlude physical objects in the Real World scene in the observer's direct line-of-sight, 102, and allows those to be replaced with computer generated Digital content in a pixel wise manner. Physical objects can be camouflaged and completely artificial objects, or remote people can be Digitally introduced into the observer's Physical environment where virtual shadows and virtual lighting can be generated on-demand. Therefore our invention allows blending of the Physical and Digital realms for a truly magical visual experience.