Oblique-Interface Light Pipe for Flexible AR Folding Angles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light pipes used in augmented reality systems are challenging to integrate aesthetically due to their length and straightness, leading to inefficiencies in folding and alignment with wearable frames, especially when mixing different light source colors.
Innovation Solution
A light pipe design comprising two optical structures with different refractive indices, allowing for flexible folding angles through refractive and reflective mechanisms, including reflective coatings and gaps, to align with the frame of glasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a straight light pipe is used, then the light pipe maintains structural simplicity and ease of manufacture, but it protrudes beyond the desired optical engine envelope and cannot be aesthetically aligned with wearable frames
Solution Approach 1:
The light pipe is divided into multiple optical structures (first optical structure, second optical structure, and intermediate optical structures) that can be independently configured. Each structure has specific optical surfaces that can be angled relative to others, allowing the overall light pipe to be folded at desired angles while maintaining manageable complexity in each individual component.
Solution Approach 2:
The patent introduces angular orientation as an additional degree of freedom by configuring optical surfaces at specific angles (e.g., first angle, second angle, third angle) relative to each other. This allows the light pipe to fold in three-dimensional space rather than being constrained to a straight line, enabling aesthetic alignment with wearable frames while controlling the overall envelope.
2Shape
If a banded optical fiber is used to curve the light pipe, then the light pipe can be folded to fit the envelope, but light propagation efficiency decreases due to inability to maintain total internal reflection
Solution Approach 1:
The patent changes the optical parameters at the interfaces between optical structures by configuring surfaces at specific angles and using optical elements with different refractive indices. This allows the light path to be redirected through controlled refraction and reflection rather than forced curvature, maintaining total internal reflection conditions and preserving light propagation efficiency while achieving the desired folded shape.
3Loss of energy
If a right-angled prism with reflective coating is used to fold the light pipe, then light propagation efficiency is maintained, but the folding angle is limited to specific angles only
Solution Approach 1:
The patent creates a dynamic and flexible optical path by using multiple optical structures with independently configurable angles and refractive indices. Rather than being fixed to specific folding angles like traditional prisms, the system can be adapted to achieve various folding angles by adjusting the configuration of intermediate optical structures and their surface angles, providing versatility while maintaining efficiency through controlled optical interactions.
4Device complexity
If the light pipe is made longer to maintain straight alignment, then structural simplicity is preserved, but it protrudes beyond the desired optical engine envelope
Solution Approach 1:
The patent achieves an effective curved or folded light path through the angular configuration of multiple optical structures rather than physically curving the light pipe. By arranging optical surfaces at specific angles and using refraction/reflection at interfaces, the light travels through a compact, folded path that fits within the desired envelope while maintaining straight segments within each optical structure for structural simplicity.
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 design enables efficient and aesthetic integration of light pipes in wearable frames by allowing for any desired folding angle, enhancing optical efficiency and alignment with system components.
Implementation Method 1
an interface between the second surface and the third surface being oblique to the longitudinal axis of the light pipe such that an input light ray to the input surface injected parallel to the longitudinal axis is output from the output surface as an output light ray non-parallel to the input light ray
Implementation Method 2
at least one outer sidewall of the first and second optical structures is coated with a reflective coating, the reflective coating constraining the optical path within the light pipe
Data Source
Figure 1
Figure 2A~2B
Figure 3~5
AI summary
A light pipe includes at least two optical structures having different refractive indices. An interface between the two optical structures is oblique to a longitudinal axis of the light pipe such that an output ray from an output surface at a distal end of the light pipe is non-parallel to an input ray that is parallel to the longitudinal axis at an input surface at a proximal end of the light pipe. Light refracts inside the light pipe between the (at least) two optical structures altering the direction of an optical path of the light through the light pipe, thereby allowing higher degrees of freedom for the selection of the angle of deviation (folding angle) of the light pipe. By optimizing various parameters of the light pipe, a desired output optical axis angle (i.e., folding angle) can be achieved that suits the desired optical engine envelope.