Multi-layer Film Filter for On-vehicle Imaging Under Low Color Rendition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
On-vehicle cameras face challenges with reduced sensitivity due to half-mirror mounting, limited view angles, and color degradation under high temperatures and poor color rendition from high-pressure sodium lamps, which affect visibility and image processing accuracy.
Innovation Solution
An imaging system with a multi-layer film filter made of inorganic materials for selective wavelength transmission, combined with an image processing section to enhance color separation and visibility under various lighting conditions, allowing for improved color discrimination and reliability across different environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a camera is mounted in a door mirror to avoid aerodynamic drag and improve vehicle design, then vehicle performance is maintained, but image sensitivity is reduced due to the half-mirror mounting
Solution Approach 1:
The camera is extracted from the door mirror assembly and mounted independently on the vehicle body (front bumper, grille, or fender). This separation eliminates the half-mirror mounting configuration that caused sensitivity reduction while maintaining the benefit of not requiring door mirror modification. The camera operates in a dedicated mounting position optimized for imaging performance.
2Reliability
If a camera is mounted in the engine room to avoid aerodynamic drag, then vehicle design is improved, but camera reliability deteriorates due to high temperature and harsh environment
Solution Approach 1:
The camera is extracted from the engine room environment and relocated to positions on the front bumper, grille, or fender. These locations provide exposure to outdoor conditions without the extreme temperatures and harsh environment of the engine room, thereby maintaining design benefits while protecting camera reliability.
Solution Approach 2:
The vehicle body structure (bumper, grille, or fender) serves as an intermediary mounting platform that positions the camera in a favorable environment. This intermediary location shields the camera from direct engine heat while maintaining optimal imaging angles and environmental exposure.
3Object-affected harmful factors
If a camera is mounted in the passenger compartment to avoid external environmental exposure, then camera protection is improved, but driver's field of view and interior comfort are deteriorated
Solution Approach 1:
The camera is extracted from the passenger compartment and mounted on the exterior vehicle body (front bumper, grille, or fender). This external mounting provides adequate environmental protection through the vehicle's exterior structure while completely eliminating the intrusion into the passenger compartment space, thereby preserving driver's field of view and interior comfort.
4Loss of energy
If high-pressure sodium lamps are used for road lighting to improve economic efficiency, then lighting cost is reduced, but color rendition is deteriorated making it difficult to recognize colors
Solution Approach 1:
The imaging spectrum is segmented into multiple discrete wavelength bands using a multi-band optical filter (transmitting blue, green, and red bands). By capturing images at these specific wavelength segments and combining them, the system reconstructs color information that compensates for the poor color rendition of high-pressure sodium lamps, enabling accurate color recognition under economically efficient lighting conditions.
Solution Approach 2:
The system changes the spectral parameters of captured light by using optical filters to select specific wavelength bands. This parameter transformation converts the limited spectral information from high-pressure sodium lamp illumination into comprehensive color data through multi-band filtering and computational combination, thereby improving color rendition while maintaining the economic benefits of sodium lamp usage.
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 system provides higher visibility than the naked eye under regular road lighting and maintains performance across high temperatures and intense light, with improved color discrimination and reduced color degradation, enabling effective vehicle monitoring.
Implementation Method 1
a multi-layer film filter, disposed above the photoelectric conversion elements and formed of inorganic materials, for selectively transmitting only a particular wavelength band of the incident light to separate a color component from the incident light
Implementation Method 2
photoelectric conversion elements for converting incident light to electricity for each of the unit pixels
Data Source
AI summary
An imaging system according to the present inventions includes an image sensor in which a plurality of unit pixels are arranged on a chip and an image processing LSI for converting color components output from the image sensor to color signals. The imaging system is configured to select only color component which have passed through filters having similar spectral characteristics to spectral characteristics of the human eye from separation filter groups forming multi-layer film filters under white light and, on the other hand, combine color components which have passed through arbitrarily selected filters of the filters the separation filter groups to output the combined color components under illumination of low rendering lightning.