Wide-Angle Imaging Lens With High Central Magnification
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Solution Overview
Problem
Existing in-vehicle camera optical systems face challenges in achieving a wide angle of view equivalent to fisheye lenses while maintaining sufficient imaging magnification in the central angle of view area, often resulting in larger camera sizes and suboptimal optical performance.
Innovation Solution
The optical system comprises a front unit and a rear unit with specific lens configurations, including aspherical lenses, to achieve a maximum half angle of view of π/2, balancing high central resolution and wide angle of view, and correcting optical distortions to ensure good visibility and reduced image deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the image sensor size is increased to achieve a wider angle of view, then the angle of view is improved, but the camera size becomes larger
Solution Approach 1:
The patent applies parameter changes by modifying the projection characteristic function from conventional fisheye projections to a new function y=f×tanθ×k(θ) where k(θ) is a correction factor. This mathematical transformation allows the optical system to achieve a maximum half angle of view of π/2 (180 degrees) while maintaining high imaging magnification in the central area, thereby widening the angle of view without proportionally increasing the camera size
Solution Approach 2:
The patent implements dynamics by creating a variable imaging magnification system where the magnification changes dynamically across different angle ranges. The correction factor k(θ) varies with the angle θ, providing high magnification for central angles (|θ|<θa) and appropriate magnification for peripheral angles (θa≤|θ|<π/2), allowing the system to adapt its characteristics to different viewing requirements without increasing overall size
2Measurement precision
If the imaging magnification in the central angle of view area is increased, then the detection accuracy is improved, but the angle of view becomes narrower
Solution Approach 1:
The patent applies local quality by creating different optical characteristics for different regions of the field of view. The correction factor k(θ) is designed to provide high imaging magnification (dy/dθ > 0.5f) for central angles where |θ|<θa, ensuring high detection accuracy for vehicles and obstacles directly ahead, while allowing different magnification characteristics for peripheral angles, thus achieving high central resolution without sacrificing overall angle of view
Solution Approach 2:
The system dynamically adjusts imaging magnification based on the angle of view through the correction factor k(θ). This creates a variable magnification system that provides high magnification in the central region for accurate detection while maintaining appropriate magnification in peripheral regions to preserve the wide angle of view, effectively resolving the contradiction between central resolution and overall field of view
3Adaptability or versatility
If a fisheye lens with wide angle of view is used, then the angle of view is improved, but the imaging magnification in the central area becomes insufficient
Solution Approach 1:
The patent transforms the projection characteristic from conventional fisheye projections (y=f×θ, y=2f×sin(θ/2), or y=f×sinθ) to a new projection function y=f×tanθ×k(θ). This parameter change in the projection function allows the system to maintain the wide angle of view capability of fisheye lenses while simultaneously improving the imaging magnification in the central area through the correction factor k(θ), which ensures dy/dθ > 0.5f for central angles
Solution Approach 2:
The patent converts the inherent limitation of fisheye lenses (low central magnification) into a benefit by applying a correction factor that enhances central area imaging. The new projection function y=f×tanθ×k(θ) takes advantage of the tanθ relationship which naturally provides higher magnification in the central region compared to linear or sine-based projections, while the k(θ) factor further optimizes this effect to ensure sufficient central imaging magnification
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 a compact in-vehicle camera with improved detection accuracy of vehicles and surroundings, maintaining high resolution in the low angle of view area and securing a wide angle of view equivalent to fisheye lenses, while suppressing optical distortion and ensuring good optical performance.
Implementation Method 1
The optical system comprises, in order from an enlargement conjugate position to a reduction conjugate position, a front unit and a rear unit
Data Source
Figure 1
Figure 2A~2B
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AI summary
An optical system (100A to 100D) includes, in order from an enlargement conjugate side to a reduction conjugate side, a front unit (101A to 101D) including a plurality of lenses, an aperture stop (ST), and a rear unit (102A to 102D) including a plurality of lenses. A projection characteristic of the optical system representing a relationship between a half angle of view and an image height on an image plane satisfies a predetermined condition.