Waveguide Optical Layout for Compact Image Projection
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Solution Overview
Problem
Existing optical elements, such as those used in head-mounted displays, require downsizing of the waveguide to enhance portability and usability.
Innovation Solution
An optical system with a projection optical system and a light guide that includes an in-coupling region and a propagation region, where the distance from the projection optical system to the entrance pupil is longer in one plane than to the in-coupling region, allowing image light rays to converge and diverge appropriately within the light guide, thereby reducing its size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the waveguide is downsized to improve portability, then the light guide size is reduced, but the optical path length and image quality may deteriorate
Solution Approach 1:
The patent positions the entrance pupil at a different axial distance from the projection optical system than the in-coupling region, creating an asymmetric optical path along the first axis. This dimensional arrangement allows the optical system to maintain effective image projection while reducing the overall light guide size, resolving the contradiction between compactness and optical quality
Solution Approach 2:
The patent modifies the optical path parameters by establishing specific distance relationships: the distance from the projection optical system to the entrance pupil in the plane perpendicular to the first axis is longer than the distance to the in-coupling region. This parameter optimization enables compact light guide design while preserving optical performance
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 configuration enables the downsizing of the light guide, allowing for a more compact optical system while maintaining effective image projection and expansion of the field of view.
Implementation Method 1
an in-coupling region for guiding the image light ray to an inside of the light guide and allowing the image light ray to travel in a direction of a first axis within the light guide
Implementation Method 2
a propagation region for allowing the image light ray from the in-coupling region to propagate in the direction of the first axis, and allowing part of the image light ray to travel in a predetermined direction including a directional component of a second axis perpendicular to the first axis
Data Source
AI summary
An optical system includes: a projection optical system for projecting an image light ray output from a display element and forming an image; and a light guide including an in-coupling region for guiding the ray to an inside of the guide and allowing it to travel in a first axis direction within the guide, and a propagation region for allowing the ray from the in-coupling region to propagate in the direction of the first axis, and allowing part of the ray to travel in a predetermined direction including a directional component of a second axis perpendicular to the first axis. In an optical path of the ray, a distance from the projection optical system to an entrance pupil of the projection optical system relative to the element in a plane perpendicular to the first axis is longer than a distance from the projection optical system to the in-coupling region.