World-Referenced Smartglasses Display Alignment With Rigid Optical Coupling
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Solution Overview
Problem
Flexible or deformable frames in head-mounted computing devices like smartglasses can cause misalignment of real and virtual images due to frame deformation, leading to visual discomfort and complexity in real-time alignment adjustments.
Innovation Solution
Rigidly coupling a world-facing radiation detector to a projection system and using an input light direction rerouter, such as a retroreflector, to adjust the angle of incidence at the waveguide surface to maintain parallel output and input directions, ensuring consistent image alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the frame is made flexible and deformable to fit the user comfortably, then the ease of operation and comfort are improved, but the alignment consistency of the display deteriorates
Solution Approach 1:
The frame is divided into flexible portions (for comfort) and rigid portions (for alignment). The rigid portions specifically house the projection system and radiation detector, while other portions remain flexible for wearing comfort. This segmentation allows each part to have optimized properties for its specific function.
Solution Approach 2:
Different portions of the frame have different rigidity properties. The portions requiring display alignment (housing the projection system and detector) are made rigid, while other portions remain flexible. This local differentiation of mechanical properties resolves the contradiction between overall flexibility and local alignment stability.
2Reliability
If rigid components are used to maintain display alignment, then the alignment consistency is improved, but the device weight increases
Solution Approach 1:
Rather than making the entire frame rigid, the rigidity is segmented and applied only to specific portions that house the projection system and radiation detector. This localized rigidity maintains alignment consistency while minimizing the overall weight compared to a fully rigid frame.
Solution Approach 2:
The frame exhibits local quality differentiation where only specific regions require rigid construction for optical alignment, while the rest of the frame can be lighter and more flexible. This optimizes the weight-rigidity tradeoff by applying rigidity only where functionally necessary.
3Reliability
If real-time alignment adjustments are implemented to compensate for frame deformation, then the display alignment consistency is improved, but the device complexity increases
Solution Approach 1:
The rigid portions are pre-configured during manufacturing to maintain the correct spatial relationship between the projection system and radiation detector. This preliminary structural configuration eliminates the need for complex real-time alignment adjustments, as the geometry is preserved by the rigid construction.
Solution Approach 2:
The alignment maintenance function is extracted from active control systems and embedded in the passive structural design. By making the housing portions rigid, the alignment consistency is achieved through structural design rather than through active sensing and adjustment mechanisms, thereby reducing device complexity.
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
Achieves consistent alignment of real and virtual images without increasing system complexity or cost, allowing for a lighter and more comfortable wearable device.
Implementation Method 1
a waveguide configured to couple the internally generated radiation into the waveguide to produce radiation in the waveguide
Implementation Method 2
an input light direction rerouter configured to adjust an initial angle of incidence of the internally generated radiation at a surface of the waveguide to produce radiation directed at an adjusted angle of incidence at the incoupler such that the output direction is substantially parallel to the initial direction of incidence
Data Source
AI summary
Improved techniques of aligning real and virtual images in an augmented reality head-mounted wearable device include rigidly coupling a world-facing radiation detector for processing real images to a projection system in a frame of the head-mounted wearable device for processing virtual images. In some implementations, the augmented reality head-mounted wearable device includes an input light direction rerouter configured to adjust an initial angle of incidence of the internally generated radiation at a surface of the waveguide to produce radiation directed at an adjusted angle of incidence at the incoupler such that the output direction is substantially parallel to the initial angle of incidence. In some implementations, the input light direction rerouter takes the form of a retroreflector that alters the input of the incident light from the projection system such that its direction is substantially a reciprocal of the output light vector.