Vehicle Display Polarization Switching for Sunglasses Visibility
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Solution Overview
Problem
Conventional vehicle display devices experience reduced virtual image luminance when polarizing sunglasses are worn due to polarization direction mismatches and component variations, leading to potential quality deterioration.
Innovation Solution
A display device with a polarization switching unit that rotates a wave plate to adjust polarization direction based on the presence of polarizing sunglasses, using a controller to detect optimal rotation angles for maximum luminance and correct for assembly deviations, ensuring S or P polarization components are emitted as principal components accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wave plate is rotated by an electric motor to switch polarization direction, then the display can adapt to both modes (with and without polarizing sunglasses), but the virtual image quality deteriorates due to rotational position deviation and component variations
Solution Approach 1:
The patent implements a feedback mechanism where the imaging device captures luminance information of the virtual image, and the controller adjusts the wave plate rotation angle based on this feedback to maximize luminance. This closed-loop control compensates for assembly variations and tolerance deviations, ensuring optimal virtual image quality in both modes (with and without polarizing sunglasses).
Solution Approach 2:
The patent performs preliminary calibration by rotating the wave plate within a prescribed range before actual use, detecting luminance values at different angles, and determining the optimal rotation angle in advance. This preliminary action ensures that the system is pre-adjusted to compensate for component variations before the occupant actually uses the display.
2Device complexity
If the wave plate rotation position is fixed according to design specifications, then the device structure is simple, but assembly variations cause deviation from optimal polarization angles
Solution Approach 1:
Instead of relying solely on precise manufacturing, the patent uses feedback from the imaging device to detect actual luminance and automatically adjusts the wave plate angle to compensate for assembly variations. This approach maintains simple device structure while achieving high manufacturing precision through active compensation.
Solution Approach 2:
The system performs self-calibration by automatically detecting its own performance (luminance) and adjusting accordingly. The controller autonomously determines the optimal wave plate angle without requiring external intervention or complex precision manufacturing, allowing the system to self-correct for assembly variations.
3Ease of operation
If the wave plate is rotated to correct polarization direction, then visibility with polarizing sunglasses is improved, but luminance may be reduced due to suboptimal rotation angles
Solution Approach 1:
The imaging device provides feedback on actual luminance levels, allowing the controller to optimize the wave plate rotation angle to maximize luminance while maintaining the correct polarization direction for visibility with polarizing sunglasses. This ensures both visibility and brightness are optimized simultaneously.
Solution Approach 2:
The patent dynamically changes the rotation angle parameter of the wave plate based on detected conditions and luminance feedback. By adjusting this parameter within a prescribed range and selecting the angle that maximizes luminance, the system maintains both visibility and brightness under varying conditions.
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 maintains high virtual image luminance by adjusting polarization direction and correcting for component variations, enhancing visibility with and without polarizing sunglasses.
Implementation Method 1
a wave plate configured to be able to emit emission light of the display while changing a polarization direction
Implementation Method 2
a reflector configured to directly or indirectly receive the emission light from the polarization switching unit, and reflect the emission light toward an eye box as a visible range for a virtual image
Data Source
AI summary
A display device for a vehicle includes: a display, a polarization switching unit, a reflector, and a controller. The polarization switching unit includes a wave plate that can cause emission light of the display to be emitted while changing a polarization direction thereof, and a drive device that can rotate the wave plate between a position of not using polarizing sunglasses and a position of using polarizing sunglasses. The controller rotates the wave plate within a prescribed range, detects luminance values for each fixed rotation angle of the wave plate within a prescribed range from imaging information of an imaging device that transmits a principal component of transmitted light of the wave plate at a position of the eye box, and sets, as a correction angle, a rotation angle of the wave plate corresponding to a maximum luminance value among the luminance values.