Onboard Camera Polarization Plate for Reflection Reduction
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Solution Overview
Problem
Conventional onboard cameras experience degraded image accuracy and contrast due to interior reflections from external light, particularly during daytime and nighttime driving, where sunlight and streetlight reflections from dashboards interfere with the image capture, and the use of polarization filters often results in excessive light attenuation and reduced sensitivity.
Innovation Solution
An onboard camera system featuring a CMOS image sensor with a polarization plate that optimizes transmittance characteristics, allowing 5-20% cross transmittance for S-polarized waves and 45-60% parallel transmittance for natural light, reducing reflections and ensuring sufficient light intake for improved image quality and night visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarization filter is installed on the front face of the camera to reduce interior reflection, then the reflection of dashboard on windshield is reduced, but the light amount is excessively attenuated and image quality deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully selecting the polarization angle of the polarization filter to be 45 degrees relative to the camera's optical axis, rather than the conventional 0 or 90 degrees. This angular parameter change allows the filter to reduce interior reflections while maintaining sufficient light transmission for image capture, resolving the contradiction between reflection reduction and light amount preservation
Solution Approach 2:
The patent employs a switchable polarization filter mechanism that can dynamically adjust or remove the polarization filter based on driving conditions (daytime vs. nighttime). This dynamic adjustment allows the system to optimize performance for different lighting conditions, reducing reflections during daytime while ensuring sufficient light intake during nighttime
2Measurement precision
If a polarization filter is installed to reduce interior reflection, then the contrast of acquired image is improved, but the sensitivity of camera is reduced
Solution Approach 1:
By changing the polarization angle parameter to 45 degrees and selecting specific transmittance characteristics (45-60% parallel transmittance for natural light), the patent achieves a balance where image accuracy is improved through reflection reduction while camera sensitivity is preserved through optimized light transmission parameters
Solution Approach 2:
The switchable polarization filter allows the system to dynamically adjust sensitivity based on lighting conditions, maintaining high image accuracy during daytime when reflections are problematic while ensuring sufficient sensitivity during nighttime by removing or adjusting the filter
3Object-affected harmful factors
If the polarization filter attenuates light to reduce reflection, then the reflection light is blocked, but the acquired image differs from human vision
Solution Approach 1:
The patent changes the transmittance parameter of the polarization filter to specific ranges (45-60% parallel transmittance for natural light, 5-20% cross transmittance for S-polarized waves) that allow sufficient light passage to maintain image fidelity to human vision while still achieving effective reflection 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 solution effectively reduces interior reflections, maintains image accuracy, and enhances night visibility by balancing light transmittance to prevent excessive attenuation, allowing the camera to capture images that resemble human vision without degrading contrast.
Implementation Method 1
a polarization plate arranged in front of the camera unit, the image-capturing device constituting the camera unit is a CMOS image sensor, and the polarization plate is a polarization plate whose cross transmittance with respect to S-polarized wave having a wavelength from 420 nm to 700 nm is 5 to 20% or a polarization plate whose parallel transmittance with respect to natural light having a wavelength from 420 nm to 700 nm is 45 to 60%
Data Source
AI summary
The onboard camera is mounted in a vehicle to shoot a driving environment of the vehicle by receiving external light from outside of the vehicle, the onboard camera includes: a camera unit having a lens unit which generates an image by receiving the external light and an image-capturing device which generates an image signal based on the image generated by the lens unit; and a polarization plate arranged in front of the camera unit, the image-capturing device constituting the camera unit is a CMOS image sensor, and the polarization plate is a polarization plate whose cross transmittance with respect to S-polarized wave having a wavelength from 420 nm to 700 nm is 5 to 20% or a polarization plate whose parallel transmittance with respect to natural light having a wavelength from 420 nm to 700 nm is 45 to 60%.