Zoom Lens Group Segmentation for Angle Stability
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Solution Overview
Problem
Conventional zoom lenses fail to provide a wide angle of view while minimizing size and weight, and they struggle to suppress variations in angles of view during focusing operations, which is essential for portable broadcast lenses.
Innovation Solution
A zoom lens configuration comprising a first lens group with positive refractive power fixed during magnification changes, a second lens group with negative refractive power moving from the object side to the image side, a third lens group with negative refractive power correcting the imaging surface, and a fourth lens group with positive refractive power fixed during magnification changes, optimized by specific conditional formulas for lens distances, radii of curvature, and Abbe's numbers to achieve compactness and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional zoom lenses are designed to achieve high variable magnification ratios, then magnification capability is improved, but the lens size and weight increase
Solution Approach 1:
The lens is divided into four distinct lens groups (first, second, third, and fourth groups) with specific refractive powers and movement characteristics. This segmentation allows each group to perform specialized functions, enabling compact design while maintaining high magnification capability through coordinated movement of specific groups rather than requiring a monolithic large lens structure.
Solution Approach 2:
The patent employs dynamic movement of the second lens group from the object side to the image side during magnification changes, and dynamic focusing by moving the 12 lens group. This dynamic configuration allows the lens to achieve variable magnification ratios without requiring a fixed, oversized lens structure, thereby reducing overall lens weight while maintaining adaptability.
2Volume of moving object
If conventional zoom lenses are designed for compact size, then lens size is reduced, but the angle of view becomes insufficient
Solution Approach 1:
The patent utilizes conditional formulas to precisely control optical parameters including the focal length of each lens group, the distance between lens groups, and the refractive indices of lens materials. By optimizing these parameters, the lens achieves a compact size while maintaining a sufficiently wide angle of view, resolving the contradiction between compactness and field coverage.
3Volume of moving object
If the first lens group is miniaturized to reduce size, then lens size is reduced, but the ability to suppress angle of view variations during focusing deteriorates
Solution Approach 1:
The first lens group is further segmented into three sub-groups (11, 12, and 13 lens groups) with different refractive powers and movement characteristics. This segmentation allows the miniaturized first lens group to maintain angle of view stability during focusing operations through the coordinated action of its sub-groups, while still achieving compact dimensions.
Solution Approach 2:
The 12 lens group within the first lens group is designed to move during focusing operations, while the 11 and 13 lens groups remain fixed. This dynamic configuration within the miniaturized first lens group enables it to suppress angle of view variations during focusing, resolving the contradiction between size reduction and stability maintenance.
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 effectively suppresses variations in angles of view, reduces size and weight, and minimizes high-order spherical aberrations, enabling high-quality imaging with a wide angle of view.
Implementation Method 1
a first lens group having a positive refractive power, which is fixed while changing magnification; a second lens group having a negative refractive power, which moves from an object side to an image side while changing magnification
Implementation Method 2
a third lens group having a negative refractive power, which corrects movement of an imaging surface while changing magnification
Data Source
AI summary
A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes an 11 lens group having a negative power, which is fixed during focusing operations, a lens group having a positive power, which moves during focusing operations, and a lens group having a positive power, which is fixed during focusing operations. The 11 lens group includes two negative meniscus lenses having concave surfaces toward an image side, and a cemented lens constituted by a biconcave lens toward an object side and a biconvex lens toward the image side. A distance D4 between the second meniscus lens and the cemented lens and the focal distance f1 of the first lens group satisfy the relationship: 0.60<D4/f1<2.0. Thereby, variations in angles of view while changing magnification are suppressed, sufficient reductions in size and weight, and high performance are achieved.