Zoom Lens Focusing Group Segmentation for Weight Reduction
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Solution Overview
Problem
Existing zoom lens systems face challenges in achieving a compact and lightweight focusing lens group for rapid and quiet focusing operations while maintaining superior optical quality, particularly in correcting field curvature during zooming.
Innovation Solution
A zoom lens system comprising a positive first lens group, a negative second lens group, and a positive rearward-remaining lens group, where the second lens group is divided into a non-moving and a moving sub-lens group, and the rearward-remaining lens group includes multiple lens groups with changing distances during zooming, satisfying specific focal length and refractive index conditions to minimize weight and aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the rear sub-lens group is configured of three lens elements, then the focusing function is achieved, but the size and weight of the focusing lens group cannot be reduced sufficiently
Solution Approach 1:
The second lens group is divided into a front sub-lens group and a rear sub-lens group, with the rear sub-lens group serving as the focusing lens group. This segmentation allows the focusing function to be isolated to a specific subgroup, enabling size and weight reduction of the moving focusing portion while maintaining the overall focusing capability of the system.
Solution Approach 2:
The focusing function is extracted from the entire lens system and assigned specifically to the rear sub-lens group. By taking out only the necessary focusing components and making them movable while keeping other lens groups fixed, the patent achieves rapid and quiet focusing operation with reduced weight and size of the moving focusing lens group.
2Weight of moving object
If a single lens element is used for the lens group behind the second lens group, then the size and weight are reduced, but field curvature fluctuation occurs during zooming
Solution Approach 1:
Different lens groups are assigned different functions and movement characteristics. The first lens group moves for focusing, the second lens group is divided with the rear sub-lens group moving for focusing, and the rearward-remaining lens group has multiple lens groups with changing distances during zooming. This local differentiation of quality and function allows each subgroup to be optimized for its specific role, correcting field curvature where needed while minimizing weight elsewhere.
3Object-affected harmful factors
If multiple lens groups are used in the rearward-remaining lens group with changing distances, then field curvature is corrected, but the device complexity increases
Solution Approach 1:
The rearward-remaining lens group is segmented into multiple lens groups with changing distances during zooming, allowing field curvature correction to be achieved through coordinated movement of these subgroups. This segmentation enables complex optical correction to be distributed across multiple simpler moving components rather than requiring a single complex mechanism.
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 miniaturized and reduced-weight focusing lens group that performs rapid and quiet focusing while effectively correcting field curvature and aberrations, ensuring superior optical quality during zooming operations.
Implementation Method 1
a zoom lens system includes a positive first lens group, a negative second lens group, and a positive rearward-remaining lens group, in that order from the object side
Data Source
AI summary
A zoom lens system includes a positive first lens group, a negative second lens group, and a positive rearward-remaining lens group. Upon zooming from the short to long focal length extremities, the distance between the first and second lens groups increases, the distance between the second and rearward-remaining lens groups decreases, and at least the first lens group and at least part of the rearward-remaining lens group moves. The second lens group includes a negative first sub-lens group which does not move during a focusing operation, and a negative second sub-lens group which moves in the optical axis direction during a focusing operation. The positive rearward-remaining lens group includes at least two lens groups, the distance therebetween mutually changing during zooming from the short focal length extremity to the long focal length extremity.