HUD Polarization Conversion for Sunglasses Visibility
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Solution Overview
Problem
Conventional HUD devices using linearly polarized light are not visible to drivers wearing polarized sunglasses, as they block the s-polarized light used for displaying virtual images on windshields or combiners, leading to reduced visibility of HUD images.
Innovation Solution
The HUD device employs a polarization conversion element, such as a polymer film with refractive index ellipsoids, to convert s-polarized light into elliptically polarized light, ensuring the HUD image can be seen even with polarized sunglasses, while also being modularized, reduced in size, and improving light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linearly polarized light (s-polarized light) is used for displaying virtual images in HUD device, then reflection characteristics are improved, but visibility is blocked when driver wears polarized sunglasses
Solution Approach 1:
The patent changes the polarization state parameter from linear polarization to elliptical polarization by introducing a polarization conversion element. This transformation allows the light to pass through polarized sunglasses while maintaining visibility, resolving the contradiction between reflection characteristics and visibility with polarized sunglasses
Solution Approach 2:
The patent introduces a polarization conversion element as an intermediary component between the light source and the windshield. This element converts s-polarized light into elliptically polarized light, enabling the light to penetrate polarized sunglasses and making the HUD image visible to drivers wearing such sunglasses
2Reliability
If conventional HUD device configuration is used, then image projection is achieved, but device size is large and light use efficiency is low
Solution Approach 1:
The patent merges the polarization conversion function into the existing optical path by integrating a polarization conversion element that can be positioned on existing mirrors or optical components. This consolidation achieves compactization without sacrificing image projection capability, reducing device size while maintaining reliability
Solution Approach 2:
The patent optimizes optical parameters including incident angles and polarization states to improve light use efficiency. By changing the polarization state and optimizing the optical path configuration, the system achieves better light utilization with a more compact form factor
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 solution allows drivers to view HUD images effectively when wearing polarized sunglasses, while also achieving cost-effective, compact, and high-efficiency image projection systems.
Implementation Method 1
means configured to convert polarization of the polarized light of the image projected from the image display apparatus
Implementation Method 2
convert s-polarized light into elliptically polarized light
Implementation Method 3
a collimator configured to convert light emitted from the light source into substantially parallel light
Implementation Method 4
a light guide on which the light emitted from the collimator is incident and which emits the light in a direction different from an incident direction
Data Source
AI summary
A HUD device and an image display apparatus for solving a problem that a HUD image cannot be seen in a HUD device that displays a virtual image when wearing the sunglasses having polarization function are provided. A head up display device for a vehicle is provided with an image display apparatus configured to project an image onto a windshield or a combiner by polarized light and means of converting polarization of polarized light of the image projected from the image display apparatus, the means being provided on a part of a light path from the image display apparatus to the windshield or the combiner.