Head-worn Display Optical Module Stray Light Management
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Solution Overview
Problem
Current wearable computing systems face challenges in providing effective see-through displays that overlay digital information onto the real world while minimizing stray light and maintaining high contrast.
Innovation Solution
The development of head-worn computing (HWC) systems that incorporate advanced optical modules, including a DLP-based upper optical module with a TIR wedge and corrective wedge, and a lower optical module with a combiner element, to manage image light and dark state light effectively, reducing stray light and enhancing contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional display optics are used in wearable computing systems, then the system structure is simple, but stray light is excessive and contrast is poor
Solution Approach 1:
The optical system is divided into multiple functional modules: an upper optical module containing a TIR wedge and corrective wedge, and a lower optical module containing a combiner element. Each module performs a specific function in managing light paths, separating image light from dark state light, and reducing stray light through structured optical segmentation.
Solution Approach 2:
A light guide plate is introduced as an intermediary component between the DLP device and the user's eye. This light guide plate manages the propagation of both image light and dark state light, facilitating their separation and directing them to appropriate destinations, thereby reducing stray light while maintaining system compactness.
2Illumination intensity
If advanced optical modules are used to reduce stray light, then contrast improves, but device complexity increases
Solution Approach 1:
The system converts dark state light (which would normally be wasted or cause stray light) into a useful component by directing it through the light guide plate to illuminate the combiner element. This dark state light contributes to the overall display brightness while the separation of image light paths maintains high contrast and deep blacks.
Solution Approach 2:
The optical design utilizes multiple spatial dimensions and light paths: image light follows one path through the TIR wedge to the combiner, while dark state light is redirected through the light guide plate. This multi-dimensional light management enables simultaneous achievement of high brightness and high contrast without requiring overly complex optical components.
3Volume of moving object
If compact optical design is used for wearable devices, then device size is reduced, but stray light control becomes difficult
Solution Approach 1:
The optical components are nested within a compact head-worn structure: the DLP device is positioned within the upper optical module, which contains the TIR wedge and corrective wedge. The lower optical module with the combiner element is integrated into the same housing, creating a nested arrangement that minimizes overall device volume while maintaining effective stray light control through proper optical path management.
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 proposed HWC systems achieve sharp contrast, high brightness, and deep blacks, providing an immersive augmented reality experience while effectively suppressing stray light and maintaining a clear view of the environment.
Implementation Method 1
an upper optical module, including a TIR wedge
Implementation Method 2
a lower optical module, including a combiner element
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The present invention relate to head-worn computing ("HWC") systems. HWC involves, in some instances, a system that mimics the appearance of head-worn glasses or sunglasses. The glasses may be a fully developed computing platform, such as including computer displays presented in each of the lenses of the glasses to the eyes of the user. In embodiments, the lenses and displays may be configured to allow a person wearing the glasses to see the environment through the lenses while also seeing, simultaneously, digital imagery, which forms an overlaid image that is perceived by the person as a digitally augmented image of the environment, or augmented reality ("AR").