Zoom Lens with Five Groups for High Magnification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compact zoom lenses with high variable magnification ratios are limited to less than 10×, failing to achieve both compactness and high performance, particularly in maintaining optical performance and focusing sensitivity across wide and telephoto ends.
Innovation Solution
A zoom lens configuration comprising five lens groups with specific refractive powers, where the distance between certain groups is adjusted during zooming to satisfy certain focal length ratios and image formation magnification criteria, ensuring a high variable magnification ratio exceeding 12× while maintaining compactness and high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a zoom lens is designed to be compact, then the size is reduced, but the variable magnification ratio is limited to less than 10×
Solution Approach 1:
The lens system is divided into five distinct lens groups with specific refractive power characteristics. Each group is assigned a particular function: the first group provides positive refractive power for wide angle coverage, the second group provides negative refractive power for telephoto extension, the third group has positive refractive power for optical performance correction, the fourth group has positive refractive power for additional focusing control, and the fifth group has negative refractive power for final image quality optimization. This segmentation enables the lens to achieve high variable magnification ratio (12× or more) while maintaining compact size by distributing optical functions across multiple specialized groups rather than relying on a single complex group.
Solution Approach 2:
The patent implements dynamic distance adjustment between lens groups during zooming operations. Specifically, the distance between the first and second lens groups is increased, the distance between the second and third lens groups is decreased, and the distance between the third and fourth lens groups is decreased when varying magnification from wide angle to telephoto end. This dynamic reconfiguration of inter-group distances enables the lens to maintain optimal optical performance across the entire magnification range while keeping the overall lens structure compact.
2Adaptability or versatility
If the variable magnification ratio is increased to over 12×, then the adaptability is improved, but the optical performance and focusing sensitivity deteriorate
Solution Approach 1:
Each lens group is designed with specific local optical characteristics tailored to its function. The first lens group has positive refractive power optimized for wide angle performance, the second lens group has negative refractive power optimized for telephoto extension, the third lens group has positive refractive power optimized for optical performance correction, the fourth lens group has positive refractive power optimized for focusing control, and the fifth lens group has negative refractive power optimized for final image quality. This local quality optimization ensures that each group contributes its specialized capability, maintaining overall optical performance even at high variable magnification ratios of 12× or more.
Solution Approach 2:
The patent employs specific parameter relationships to maintain optical performance across the zoom range. Formula (H) establishes that 0.10 ≤ fw/f3 < 0.15, where fw is the focal length of the entire lens system at the wide angle end and f3 is the focal length of the third lens group. This parameter constraint ensures that the optical characteristics are balanced appropriately. Additionally, Formula (C) specifies that −0.65 ≤ (1−(β5T)2) < 0.05, where β5T is the image formation magnification of the fifth lens group at telephoto end, which controls focusing sensitivity and optical performance. These parameter changes and constraints enable the lens to maintain reliable optical performance while achieving high variable magnification ratios.
3Adaptability or versatility
If the distance between lens groups is adjusted for high magnification ratio, then the variable magnification ratio is improved, but the device complexity increases
Solution Approach 1:
Multiple lens groups are combined into a single integrated optical system with coordinated movement. The first, second, third, fourth, and fifth lens groups are positioned and moved together as a unified structure, sharing common support mechanisms and coordination controls. This merging approach reduces the overall complexity compared to having separate independent groups, while still enabling the necessary distance adjustments between groups to achieve high variable magnification ratios of 12× or more.
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 enables a zoom lens with a high variable magnification ratio of over 12×, achieving compactness and high performance by optimizing the movement and refractive power distribution of lens groups, thereby maintaining optical performance and reducing focusing complexity.
Implementation Method 1
a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power
Data Source
AI summary
A zoom lens substantially consists of, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group. When varying magnification, the distances between adjacent lens groups are changed, while all of the lens groups are moved with respect to an image formation position. If β5T represents the image formation magnification of the fifth lens group when focusing on infinity at the telephoto end, fw represents the focal length of the entire lens system at the wide angle end, and f3 represents the focal length of the third lens group, formula (Ca): −5.00≦1−(β5T)2≦−3.30 and formula (H): 0.10<fw/f3<0.50 are satisfied.