Wavelength Filter Segmentation for Compact Vehicle Camera Systems
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Solution Overview
Problem
Existing camera systems for driver and passenger monitoring in moving vehicles face challenges in reducing the overall size of the imaging optical system while maintaining high sensitivity and accurate image capture, especially when dealing with oblique angles of incidence.
Innovation Solution
The camera system incorporates a wavelength filter with perpendicularly and obliquely incident regions, where the principal ray is incident perpendicularly and obliquely, respectively, and an image sensor sensitive to a predetermined wavelength, allowing higher transmittance through the obliquely incident region, reducing the power requirements of the lens system and enabling efficient image capture without the need for zero-degree incidence across the entire filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the principal ray is made to incident perpendicularly on the entire wavelength filter to reduce spectral shift, then the imaging optical system size increases, but the transmission accuracy is improved
Solution Approach 1:
The wavelength filter is divided into a perpendicularly incident region and an obliquely incident region, where each region has different optical properties optimized for its specific function. The perpendicularly incident region maintains spectral accuracy while the obliquely incident region enables compact system design by accepting oblique rays with higher transmittance.
2Volume of moving object
If the imaging optical system is reduced in size, then the overall device becomes more compact, but the sensitivity for capturing oblique angles decreases
Solution Approach 1:
The obliquely incident region of the wavelength filter is designed with higher transmittance for oblique rays, specifically optimizing the filter's local properties to maintain sensitivity even when the optical system is compact and rays must travel at oblique angles.
3Ease of manufacture
If the wavelength filter uses uniform transmittance across all incident angles, then the manufacturing is simpler, but the performance at oblique angles deteriorates
Solution Approach 1:
The wavelength filter employs different transmittance characteristics in different regions: the perpendicularly incident region has standard transmittance while the obliquely incident region has enhanced transmittance for oblique rays, optimizing performance for both regions simultaneously.
Solution Approach 2:
The wavelength filter is segmented into functionally distinct regions with different optical properties, allowing each region to be optimized independently for its specific incident angle requirements.
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
This configuration allows for compact imaging optics and enhanced sensitivity in capturing images of individuals on board moving vehicles, particularly at oblique angles, thereby improving the monitoring system's effectiveness and reducing the overall size of the imaging system.
Implementation Method 1
The imaging optical system has light coming from a subject passed through the wavelength filter and imaged on the image capturing plane
Implementation Method 2
The image sensor has sensitivity to light ray having a predetermined wavelength
Implementation Method 3
The imaging optical system has light coming from a subject passed through the wavelength filter and imaged on the image capturing plane
Data Source
AI summary
A camera system includes an image sensor, a wavelength filter, and an imaging optical system. The image sensor has an image capturing plane. The imaging optical system is configured to have light coming from a subject passed through the wavelength filter and imaged on the image capturing plane. The wavelength filter has a perpendicularly incident region and an obliquely incident region. On the perpendicularly incident region, a principal ray, which has passed through the imaging optical system, is incident perpendicularly. On the obliquely incident region, a principal ray, which has passed through the imaging optical system, is incident obliquely. The image sensor has sensitivity to a light ray having a predetermined wavelength. The light ray having the predetermined wavelength is transmitted at a higher transmittance through at least a part of the obliquely incident region than through the perpendicularly incident region.