Double-Folded Light Path for Head-Mounted Device Parallax Elimination
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Solution Overview
Problem
Incorporating optical components such as displays and cameras into head-mounted devices is challenging due to limited space, leading to suboptimal performance as components may not be mounted in desired locations, resulting in issues like motion parallax when capturing and displaying real-world images.
Innovation Solution
An optical system with a double-folded light path, utilizing a reflective polarizer and a partially reflective mirror, virtually shifts the position of forward-facing components like cameras and displays to align with the user's eye boxes, eliminating parallax and improving image alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forward-facing components are mounted on the front side of the housing, then the components are spatially separated from the eye boxes, but this causes motion parallax and misalignment between captured images and the user's field of view
Solution Approach 1:
The patent introduces an optical system with a double-folded light path as an intermediary between the forward-facing component and the user's eye. This optical system includes a first reflective surface and a second reflective surface that work together to shift the apparent position of the forward-facing component, thereby eliminating motion parallax and improving image alignment without requiring physical relocation of the component.
2Manufacturing precision
If the optical system uses a double-folded light path with reflective surfaces separated by a given distance, then the forward-facing component position is virtually shifted toward the eye box, but this increases the complexity of the optical system
Solution Approach 1:
The patent employs a double-folded light path that utilizes multiple reflective surfaces arranged in a specific spatial configuration. By folding the light path through multiple reflections between the first and second reflective surfaces, the system achieves precise virtual position shifting of the forward-facing component without requiring large physical separations, thereby managing optical system complexity while maintaining manufacturing precision.
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 solution ensures that images from forward-facing components are displayed without parallax, enhancing user experience by maintaining image alignment with the user's field of view, even during head movements, and making the displayed face images appear lifelike and parallax-free to external observers.
Implementation Method 1
The optical system may have a reflective polarizer and a partially reflective mirror that are separated by a given distance. The optical system may virtually shift the forward-facing component toward the eye box by twice the given distance.
Data Source
AI summary
An electronic device such as a head-mounted device may have a user display for displaying an image to a user. The image may be displayed at an eye box after passing through a lens that is interposed between the display and the eye box. A forward-facing component such as a forward-facing camera and/or an externally viewable display may be supported in the housing. The forward-facing component may be overlapped by an optical system. The optical system may have a double-folded light path that virtually shifts the position of the forward-facing component. The optical system may have a reflective polarizer and a partially reflective mirror that are separated by a given distance. The optical system may virtually shift the forward-facing component toward the eye box by twice the given distance.