Plastic Aspherical Imaging Lens System with Cemented Elements
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Solution Overview
Problem
Conventional imaging lens systems for monitoring and in-vehicle cameras use a large number of glass lenses, leading to high costs and reduced imaging performance due to significant temperature changes, with existing systems having a relatively large F-value and significant field curvature and lateral aberration.
Innovation Solution
An imaging lens system comprising a negative meniscus lens, a positive lens, a negative lens, a positive lens, and a meniscus lens, with an aperture stop positioned between the second and third lenses, and the lens surfaces of the third and fourth lenses bonded, using aspherical plastic lenses to reduce the number of lenses and improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass lenses are used in imaging lens system, then temperature resistance is improved, but manufacturing cost increases and mass production becomes difficult
Solution Approach 1:
The patent changes the material parameter from glass to plastic (resin), enabling mass production through injection molding while achieving sufficient heat resistance for camera applications. This material substitution resolves the contradiction by providing a cost-effective alternative that maintains adequate temperature resistance.
Solution Approach 2:
The patent uses composite lens structures combining plastic lenses with specific coating layers and bonding interfaces. The cemented lens structure (third lens bonded to fourth lens) creates a composite system that achieves both cost-effectiveness and thermal stability through material combination.
2Ease of manufacture
If aspherical plastic lenses are used, then manufacturing cost decreases and mass production becomes possible, but imaging performance may deteriorate
Solution Approach 1:
The patent employs aspherical surfaces on multiple lenses (first, second, third, and fourth lenses) to correct optical aberrations. The aspherical shapes enable plastic lenses to achieve glass-level imaging performance by eliminating spherical aberration and other distortions, resolving the contradiction between material choice and optical quality.
Solution Approach 2:
The patent optimizes various parameters including refractive indices (1.503-1.676), Abbe numbers (23.4-36.9), and aspherical coefficients to achieve superior imaging performance from plastic lenses. These parameter optimizations ensure that plastic aspherical lenses meet the precision requirements previously only achievable with glass.
3Power
If F-value is reduced for better lens speed, then imaging performance improves, but field curvature and lateral aberration increase
Solution Approach 1:
The patent divides the optical system into five distinct lens groups with specific functions: negative meniscus (field curvature correction), positive (light gathering), negative (aberration correction), positive (focus), and meniscus (distortion correction). This segmentation allows each lens to address specific aberrations while maintaining overall fast lens speed.
Solution Approach 2:
The cemented lens structure (third lens bonded to fourth lens) creates a composite optical element that effectively controls lateral aberration and field curvature. The bonding interface and material combination enable correction of these aberrations while maintaining the fast F-value of F/2.0.
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 provides an imaging lens system with excellent lens speed, high imaging performance, and minimal deterioration even with temperature changes, while being less expensive and reducing lateral aberration and field curvature.
Implementation Method 1
the lens surface on the image side of the third lens and the lens surface on the object side of the fourth lens are bonded to each other
Data Source
AI summary
An imaging lens system includes: in order from an object side, a first lens including a negative meniscus lens having a convex surface facing the object side, a second lens including a positive lens having a convex surface facing the object side, a third lens including a negative lens having a concave surface facing an image side, a fourth lens including a positive lens having a convex surface facing the object side, and a fifth lens including a meniscus lens having a concave surface facing the image side, in which: the imaging lens system further includes an aperture stop arranged on the object side or the image side of the second lens, and the lens surface on the image side of the third lens and the lens surface on the object side of the fourth lens are bonded to each other.