Waveguide Projection Substrate With Polarization Leakage Reduction
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Solution Overview
Problem
Conventional eyeglass-type devices with optical systems suffer from complex configurations and leakage of image light in unintended directions, causing the user's eyes to appear glowing.
Innovation Solution
A projection optical system incorporating a projection substrate with an optical waveguide and a polarization reduction plate to reduce leakage light, using a polarization reduction plate with an air layer between itself and the optical waveguide to minimize light emission in unintended directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an optical system is incorporated into limited space for eyeglass-type devices, then the device can be worn as glasses, but the optical system becomes complex
Solution Approach 1:
The patent combines the waveguide and polarization reduction plate into a single integrated projection substrate structure. The polarization reduction plate is formed as part of the substrate itself rather than being a separate component, merging multiple functions into one element to reduce overall device complexity while maintaining the eyeglass-form factor
2Illumination intensity
If light is projected through the optical waveguide, then image light can be displayed to the user, but leakage light is emitted in directions other than toward the user
Solution Approach 1:
The patent utilizes the polarization characteristics of leaked light and converts this previously harmful effect into a beneficial one. By introducing the polarization reduction plate with specific polarization characteristics, the leaked light that would normally cause glowing eyes is instead selectively attenuated, while the desired image light is preserved. The harmful leakage is transformed into a controlled filtering mechanism
3Object-generated harmful factors
If a polarization reduction plate is added to reduce leakage light, then leakage light is reduced, but the configuration becomes more complex
Solution Approach 1:
The polarization reduction plate is integrated directly into the projection substrate as a formed part of the substrate structure itself, rather than being a separate add-on component. This merging of the polarization reduction function into the substrate eliminates the need for additional discrete parts and assembly steps, thereby reducing overall device complexity while achieving effective leakage light reduction
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 system effectively reduces leakage light, ensuring the user's eyes do not appear glowing and maintains a simple configuration.
Implementation Method 1
a polarization reduction plate that (i) is provided on the first surface side with an air layer between itself and the optical waveguide, (ii) covers at least a part of the optical waveguide, and (iii) reduces light with a polarization direction from the image light leaking from the first surface of the projection substrate
Data Source
AI summary
A projection optical system including: a projection substrate for projecting an image light onto a second surface while transmitting at least a part of light, that is incident from a first surface, to the second surface opposite to the first surface, the projection substrate having an optical waveguide; and a polarization reduction plate that is provided on the first surface side with an air layer between itself and the optical waveguide, covers at least a part of the optical waveguide, and reduces light with a polarization direction from the image light leaking from the first surface of the projection substrate, wherein the optical waveguide guides at least a part of projection light for projecting the image light, and emits the projection light as the image light from the second surface.