Head-Mounted Display Optical Path Redirection Using Light Reflecting Member
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Solution Overview
Problem
The existing image display devices for head-mounted displays have limited flexibility in arranging the image forming devices due to their placement on the viewer side of the light guide panels, restricting the degree of freedom in positioning and potentially causing discomfort from heat emission.
Innovation Solution
The display apparatus positions the light reflecting member between the image forming device and the light guide panel, allowing for increased flexibility in arranging the image forming device and reducing heat-related discomfort by placing it away from the viewer's head, with the light guide panel interposed between the light reflecting member and the image forming device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the image forming device is placed on the viewer side of the light guide panel, then the optical path is simplified, but the degree of freedom in arranging the image forming device is limited and heat-related discomfort increases
Solution Approach 1:
The patent introduces a light reflecting member positioned at an angle (e.g., 45 degrees) relative to the light guide panel, changing the spatial dimension of light propagation. This allows the image forming device to be positioned away from the viewer's head while still delivering light to the eye through the light guide panel, thereby increasing arrangement flexibility without significantly complicating the optical path.
Solution Approach 2:
The light reflecting member acts as an intermediary element between the image forming device and the light guide panel. It receives light from the image forming device and redirects it into the light guide panel, enabling flexible positioning of the image forming device while maintaining efficient light coupling.
2Length of stationary object
If the image forming device is placed close to the viewer's head, then the optical path length is reduced, but heat-related discomfort increases
Solution Approach 1:
The optical path is segmented into multiple sections: the image forming device, the light reflecting member, the light guide panel, and the eye. This segmentation allows the image forming device to be positioned away from the viewer's head (reducing heat exposure) while the light guide panel delivers the light over a longer distance without significant loss, as the light is confined within the light guide panel through total internal reflection.
3Object-affected harmful factors
If the light reflecting member is positioned away from the light guide panel, then heat-related discomfort is reduced, but astigmatism and stray light issues may increase
Solution Approach 1:
The light reflecting member is designed with specific local properties: a reflective surface with precise angular orientation (e.g., 45 degrees) and potentially different surface qualities at different locations. This ensures that light is reflected at the correct angle into the light guide panel while minimizing stray light and preventing astigmatism, even when the image forming device is positioned away from the viewer's head.
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 configuration enhances the degree of freedom in arranging the image forming device, reduces heat-related discomfort, and minimizes astigmatism and stray light issues, while maintaining image quality and visibility.
Implementation Method 1
a light guide panel 121 that causes incident light to propagate therein by total reflection
Data Source
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AI summary
A display apparatus includes: a frame (10) to be mounted on the head of a viewer; and an image display device (100) attached to the frame (10). The image display device (100) includes: an image forming device (111); and an optical device (120) that guides an image from the image forming device (111) to an eye of the viewer. The optical device (120) includes: a first deflecting unit (130) that deflects the image from the image forming device (111); and a second deflecting unit (140) that deflects the image deflected by the first deflecting unit (130), toward the eye (21) of the viewer. A light reflecting member (151) is further provided to face the image forming device (111), with the optical device (120) being interposed between the image forming device (111) and the light reflecting member (151). Light emitted from the image forming device (111) passes through the optical device (120), is reflected by the light reflecting member (151), reenters the optical device (120), and is deflected by the first deflecting unit (130).