Image Projection Device Polarization Adjustment for Sunglasses Visibility
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Solution Overview
Problem
Image projection devices in vehicles face visibility issues when polarized sunglasses are worn due to the low reflectance of P-polarized light and high reflectance of S-polarized light on windshields, leading to S-polarized light being cut by the sunglasses, making it difficult for occupants to see projected images.
Innovation Solution
An image projection device that emits P-polarized light and includes a polarization adjustment unit to adjust the polarization direction of the light, ensuring it aligns with the windshield's curvature, thereby enhancing visibility even with polarized sunglasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If S-polarized light is used for image projection onto the windshield, then the reflectance of the projected light is high, but the visibility is reduced when polarized sunglasses are worn
Solution Approach 1:
The invention changes the polarization parameter of the projected light from S-polarized to P-polarized light. This parameter change allows the light to be reflected effectively by the windshield while remaining visible through polarized sunglasses, as P-polarized light is not blocked by the S-polarizing filter in the sunglasses.
Solution Approach 2:
Instead of using S-polarized light which is traditionally reflected by windshields, the invention inverts the approach by using P-polarized light. This inversion resolves the conflict between high reflectance and visibility through polarized sunglasses, as P-polarized light behaves differently when interacting with the windshield and sunglasses combination.
2Reliability
If P-polarized light is used for image projection, then the visibility with polarized sunglasses is improved, but the reflectance on the windshield is low
Solution Approach 1:
The invention applies local quality by making the polarization state of light position-dependent across the windshield. Different regions of the windshield receive light with different polarization orientations, allowing each local area to optimize both reflectance and visibility through sunglasses simultaneously.
Solution Approach 2:
The invention uses a composite approach by combining P-polarized light with a curved windshield surface. This combination creates a system where the curved surface modifies the polarization state of P-polarized light to achieve both adequate reflectance and visibility through polarized sunglasses.
3Reliability
If the polarization direction is adjusted according to the curved surface shape of the windshield, then the visibility is secured, but the device complexity increases
Solution Approach 1:
The invention utilizes the curved surface shape of the windshield to achieve the desired polarization adjustment. The curvature of the windshield naturally modifies the polarization state of the projected light, eliminating the need for additional complex polarization adjustment mechanisms while still achieving visibility through polarized sunglasses.
Solution Approach 2:
The windshield's curved surface serves the dual function of both displaying the projected image and automatically adjusting the polarization direction of the light. This self-service approach eliminates the need for separate polarization adjustment devices, reducing system complexity while maintaining visibility.
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 device ensures clear visibility of projected images by adjusting the polarization direction of light to match the windshield's shape, allowing P-polarized light to be effectively reflected and seen through polarized sunglasses.
Implementation Method 1
the polarization direction of irradiation light emitted from an image irradiation unit is set to be S-polarized with respect to the windshield... the image light irradiated from the projection optical unit includes P-polarized light with respect to the display unit... a polarization adjustment unit configured to adjust a polarization direction of the image light
Implementation Method 2
reflection of light on the windshield tends to have low reflectance of a P-polarized component and high reflectance of an S-polarized component... the irradiation light reaching a position of a viewpoint is only S-polarized light... the image light irradiated from the projection optical unit includes P-polarized light
Data Source
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AI summary
Provided is an image projection device capable of ensuring visibility even when polarized sunglasses or the like are used. Provided is an image projection device (100) for projecting a projection image onto a display unit (WS) for displaying a virtual image, comprising: an image irradiation unit (10) that irradiates image light (L1); and a projection optical unit (20) that projects the image light (L1) as a projection image onto the display unit (WS). The image light (L1) irradiated from the projection optical unit (20) includes p-polarized light with respect to the display unit (WS). The image projection device (100) comprises a polarization adjustment unit (30) that adjusts the polarization direction of the image light (L1).