Head-Mounted Display Light Guide with Absorption Layers
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Solution Overview
Problem
Existing head-up display systems suffer from 'ghost spots' due to inappropriate angular components of image light being misdirected onto the viewer's retina, causing unwanted light spots that detract from the intended image.
Innovation Solution
Incorporating a light guide member with tilted optical layers, including absorption and transflective layers, to absorb and redirect inappropriate angular components of image light, ensuring only correctly angled light reaches the viewer's eye, thereby reducing ghost spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a light guide member with prism reflection surface and transflective surfaces is used to guide image light, then the image light can be directed to the viewer's eyes, but ghost spots are produced due to inappropriate angular components of light
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using the light absorption layer to absorb the harmful inappropriate angular components of light that would otherwise create ghost spots. The absorption layer transforms the harmful scattered light into absorbed energy, eliminating the ghost spot effect while preserving the useful parallelized light flux for clear image display.
Solution Approach 2:
The patent applies local quality by introducing a light absorption layer with specific optical properties at a particular location within the light guide member. This layer has different optical characteristics (light absorbing) compared to the surrounding transparent regions, allowing it to selectively target and absorb inappropriate angular components of light while leaving the appropriate light flux unaffected.
2Area of stationary object
If light from off-center positions on the display device is guided through the substrate, then more of the display area is visible, but the prism reflection surface and transflective surfaces change part of the parallelized light flux to non-parallelized light flux with incorrect angles
Solution Approach 1:
The patent applies the intermediary principle by introducing a light absorption layer as a mediator between the prism reflection surface and the final light output. This intermediate layer selectively interacts with the light flux, absorbing the inappropriate angular components that would otherwise reach the viewer as ghost spots, while allowing the correctly angled light to pass through.
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
Effectively minimizes ghost spots by selectively absorbing inappropriate angular components, improving the clarity and accuracy of the displayed image by ensuring only intended light reaches the viewer's retina.
Implementation Method 1
a first light absorption layer that absorbs part of the guided image light
Implementation Method 2
a first transflective layer that reflects at least part of the image light absorbed by the first light absorption layer toward the light exiting portion
Implementation Method 3
diffused light from each position on the display device is converted info a parallelized light flux
Implementation Method 4
the parallelised light flux is then incident on the substrate and totally reflected off a prism reflection surface of the substrate
Data Source
AI summary
A head-mounted display that guides image light displayed by an image formation unit and focuses the image light on a viewer's side includes a light guide member that angularly converts the image light incident from the image formation unit based on reflection at a plurality of transflective layers, and a light absorption layer is disposed on each of the transflective layers. The light guide member has a light incident surface through which the image light is introduced into the light guide member, a prism reflection surface that is disposed at an end of the light guide member, serves as one of the plurality of transflective layers, and reflects the image light introduced through the light incident surface, and the light absorption layers disposed between the light guide member and the prism reflection surface.