Zoom Lens System with Segmented Second Group for Compact Autofocus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses face challenges in achieving a compact, high-performance optical system that supports both zoom and focus operations efficiently, particularly in digital camera systems.
Innovation Solution
The proposed zoom lens system consists of a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent lens group. The second lens group is further divided into sub-groups with specific refractive powers, allowing for adjustments in distance between lens groups during zoom and focus operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a positive-lead zoom lens configuration is used to extend the telephoto focal length, then the focal length range is improved, but the optical system size increases
Solution Approach 1:
The second lens group is divided into three sub-groups (G2a, G2b, G2c) with different refractive powers. This segmentation allows each sub-group to be optimized for specific functions, enabling compact design while achieving extended telephoto focal length through coordinated movement of the sub-groups during zooming
Solution Approach 2:
The patent implements dynamic adjustment of distances between lens groups during zooming. Specifically, the distance between G1 and G2 increases while the distance between G2 and the rear lens group decreases, allowing the system to achieve variable focal lengths in a compact configuration rather than requiring fixed extended spacing
2Weight of moving object
If the inner focus method is used to reduce focusing lens group weight, then the weight is reduced, but the focusing speed and precision may be affected
Solution Approach 1:
The second lens group is segmented into sub-groups G2a, G2b, and G2c, where G2b serves as the focusing lens group. This segmentation allows G2b to be designed as a lightweight component optimized for rapid focusing movement, while the other sub-groups provide the necessary optical power to maintain focusing precision despite the reduced mass of the moving group
Solution Approach 2:
Different sub-groups are assigned different refractive powers and functions: G2a has positive refractive power, G2b has negative refractive power and is optimized for focusing movement, and G2c has negative refractive power. This local optimization allows G2b to be lightweight for fast focusing while the combined system maintains the optical performance needed for precise focusing
3Volume of moving object
If lens groups are moved closer together during zooming to reduce size, then compactness is improved, but optical performance may deteriorate
Solution Approach 1:
The patent implements dynamic adjustment of inter-group distances during zooming: the distance between G1 and G2 increases while the distance between G2 and the rear lens group decreases. This dynamic reconfiguration allows the system to maintain optimal optical performance at each focal length setting while keeping the overall system compact, rather than using fixed spacing
Solution Approach 2:
Dividing the second lens group into three sub-groups with different refractive powers allows for more flexible spatial arrangement. The sub-groups can be positioned and spaced to optimize optical performance at different focal lengths, enabling the system to maintain high image quality throughout the zoom range despite the compact overall size
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
This configuration enables a compact optical system with improved optical performance across the entire zoom and focus range, while also facilitating high-speed automatic focusing and reducing the weight of the focusing lens group.
Implementation Method 1
a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a subsequent (rear) lens group GR
Data Source
AI summary
A zoom lens system includes a first lens group; a second lens group; and a subsequent lens group arranged in that order from the object side. The second lens group consists of a second lens group-a, a second lens group-b, and a second lens group-c arranged in that order from the object side. A distance between the first lens group and the second lens group increases and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.