Virtual Image Display Device Sunglasses Detection
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Solution Overview
Problem
Head-up displays struggle to provide optimal image visibility for users wearing polarized sunglasses due to the polarization-dependent reflectance of windshields, resulting in either dark images for non-wearers or inadequate brightness for wearers.
Innovation Solution
A virtual image display device that selectively projects s-polarized and p-polarized light components onto a windshield, measuring their reflectance to determine if polarized sunglasses are being worn and adjusting the projection accordingly to ensure suitable brightness and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If s-polarized light is used for projection, then visibility for users without polarized sunglasses is improved, but visibility for users wearing polarized sunglasses deteriorates
Solution Approach 1:
The patent implements dynamic switching between s-polarized and p-polarized projection modes based on detection of whether the user is wearing polarized sunglasses. The system transitions from a static projection approach to a dynamic one that adapts to user conditions, resolving the contradiction between optimizing for non-wearers and accommodating wearers
Solution Approach 2:
The patent changes the polarization parameter of the projection light from fixed s-polarization to variable polarization states. By switching between s-polarized and p-polarized light modes, the system adapts to different user conditions, resolving the visibility contradiction for different sunglasses types
2Adaptability or versatility
If p-polarized light is used for projection, then compatibility with polarized sunglasses is improved, but visibility for users without polarized sunglasses deteriorates
Solution Approach 1:
The system dynamically selects between p-polarized and s-polarized projection modes based on real-time detection of user sunglasses status. When polarized sunglasses are detected, the system switches to p-polarized mode; otherwise, it uses s-polarized mode for optimal visibility
Solution Approach 2:
The polarization parameter of the projection light is changed from fixed to variable, allowing the system to switch between s-polarized and p-polarized states. This parameter adaptation resolves the contradiction by matching the projection polarization to the user's sunglasses type
3Adaptability or versatility
If both s-polarized and p-polarized projection modes are always available, then adaptability to different users is improved, but power consumption and light source life deteriorate
Solution Approach 1:
Instead of maintaining both s-polarized and p-polarized light sources continuously, the system activates only the polarization mode needed for the current user condition. This local quality approach applies full resources to the required mode rather than maintaining all modes simultaneously, reducing power consumption while preserving adaptability
Solution Approach 2:
The system uses the windshield reflection itself as a measurement medium to detect polarized sunglasses, eliminating the need for separate detection hardware. This self-service approach reduces system complexity and power consumption while maintaining the ability to adapt to different users
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 automatically determines the presence of polarized sunglasses and adjusts the image display light to maintain optimal brightness and visibility for both users with and without polarized sunglasses, reducing power consumption and extending the life of light sources.
Implementation Method 1
the reflectance of a common windshield made of glass, etc. has polarization dependency, and the p-polarized component is less easily reflected than the s-polarized component
Implementation Method 2
When the user is wearing polarized sunglasses, the s-polarized component that is easily reflected by the windshield is shielded by the polarized sunglasses
Data Source
AI summary
A virtual image display device includes: an image projection unit that selectively projects a first projection light linearly polarized in a first direction and a second projection light linearly polarized in a second direction orthogonal to the first direction to a windshield; a reflected light measurement unit that measures an intensity of light incident from the windshield into the image projection unit along a light path in which the first projection light and the second projection light are projected; and a determination unit that determine whether a user is wearing polarized sunglasses that shield a component linearly polarized in the first direction, based on a first light intensity measured by the reflected light measurement unit when the first projection light is projected and a second light intensity measured by the reflected light measurement unit when the second projection light is projected.