Compact Imaging Lens System for Autonomous Driving
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Solution Overview
Problem
Existing imaging lens systems for car-mounted cameras face challenges in achieving compactness and sufficient brightness, with large front lenses prone to damage and long total track lengths hindering compactness, and F-numbers around 2.4 to 3.0 being too low for instantaneous sensing capabilities required for autonomous driving.
Innovation Solution
An imaging lens system comprising a front lens group with a meniscus lens and a rear lens group, including a cemented lens, optimized to satisfy specific focal length ratios and lens power relationships, ensuring compactness and reduced aberrations, thereby enhancing brightness and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a stereographic projection lens system is used to capture a larger peripheral area, then the field of view is improved, but the ratio of image height change to angle of view change becomes non-uniform, leading to sensing accuracy degradation
Solution Approach 1:
The patent changes the projection type from stereographic to equidistant projection, which fundamentally alters the mathematical relationship between angle of view and image height. In equidistant projection, the image height is directly proportional to the angle of view (h = f·θ), ensuring uniform scaling across the entire field of view. This parameter change in the projection geometry resolves the non-uniform scaling issue while maintaining wide-angle capture capability.
2Illumination intensity
If the front lens diameter is increased to improve light gathering, then brightness is improved, but the lens becomes more prone to damage from flying stones and the system becomes less compact
Solution Approach 1:
The patent achieves higher brightness not by increasing the front lens diameter, but by optimizing the F-number to 1.8 or lower through improved optical design. This allows the use of a smaller front lens diameter while maintaining or exceeding the brightness of systems with larger lenses, thereby reducing vulnerability to stone damage and improving compactness.
Solution Approach 2:
The lens system is divided into multiple lens groups with specific focal length ratios (front lens group focal length / rear lens group focal length between 0.3 and 0.6). This segmentation allows each group to be optimized for its specific function while collectively achieving the desired brightness and compactness, avoiding the need for a single large front lens.
3Manufacturing precision
If the total track length of the lens system is increased to improve imaging performance, then optical quality is improved, but compactness is degraded
Solution Approach 1:
The patent optimizes the ratio of front lens group focal length to rear lens group focal length to be between 0.3 and 0.6, and sets the F-number to 1.8 or lower. These parameter optimizations enable high-quality imaging with a shortened total track length, achieving compactness without sacrificing optical performance.
4Illumination intensity
If the F-number is increased (lower value) to improve brightness, then instantaneous sensing capability is improved, but the lens system becomes less compact
Solution Approach 1:
The patent sets the F-number to 1.8 or lower and optimizes the focal length ratio between lens groups, which enables high brightness without requiring a longer total track length. The optimized optical configuration allows light to be efficiently gathered and focused, achieving F≤1.8 while maintaining compact dimensions.
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 allows for a compact and bright imaging lens system that supports accurate and instantaneous sensing, crucial for autonomous driving applications, by optimizing the lens configuration to achieve the required focal length ratios and reduce aberrations.
Implementation Method 1
a first lens, the first lens being a meniscus lens having negative power with an object-side surface whose convex surface faces an object side
Implementation Method 2
a second lens, the second lens being a meniscus lens with the object-side surface whose concave surface faces the object side
Implementation Method 3
a fifth lens and a sixth lens constituting a cemented lens
Data Source
AI summary
An imaging lens system includes, sequentially from an object side toward an image side: a front lens group Gf including: a first lens, which is a meniscus lens having negative power with an object-side surface whose convex surface faces the object side; a second lens, which is a meniscus lens with the object-side surface whose concave surface faces the object side; and a third lens having positive power; an iris; and a rear lens group Gr including: a fourth lens having positive power; a fifth lens, a sixth lens constituting a cemented lens; and a seventh lens. The imaging lens system satisfies a following Expression (1):2.0<Frg/F<3.0 (1)where Frg is a composite focal length of the rear lens group Gr and F is a focal length of an entire optical system.