Compact Zoom Lens with Differential Group Movement
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Solution Overview
Problem
Existing zoom lenses for mirrorless cameras are large in diameter due to the significant movement of lens groups during zooming, which fails to meet the demand for downsizing while maintaining good optical performance.
Innovation Solution
A zoom lens configuration that includes a first lens group with negative refractive power and subsequent groups with specific refractive powers, allowing for compact design and excellent optical performance. The configuration includes a Gp1 group, Gn1 group, Gp2 group, Gn2 group, and a GL group, with an aperture diaphragm disposed closer to the object side than the Gp2 group, and intervals between adjacent lens groups changing during zooming and focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the amount of movement of lens groups during zooming is large, then the zoom lens can achieve high magnification, but the total optical length becomes long and the lens diameter becomes large
Solution Approach 1:
The patent employs a dynamic zoom mechanism where the first lens group and second lens group move by different amounts during zooming. Specifically, the first lens group moves a larger distance while the second lens group moves a smaller distance, allowing the system to achieve high magnification ratios without requiring all lens groups to traverse long distances, thus reducing the overall optical length while maintaining zoom capability
Solution Approach 2:
The zoom lens is divided into multiple lens groups (first lens group, second lens group, and subsequent groups) with different functions. The first lens group primarily handles zooming motion, while the second lens group and subsequent groups maintain relatively fixed positions or move minimally. This segmentation allows the zoom function to be isolated to specific groups, reducing the total optical length required while achieving high magnification
2Adaptability or versatility
If the amount of movement of lens groups during zooming is large, then the zoom lens can achieve high magnification, but the lens diameter becomes large
Solution Approach 1:
The patent uses differential movement of lens groups during zooming, where the first lens group moves significantly while the second lens group moves minimally. This dynamic arrangement allows the light flux to be controlled more efficiently, reducing the required aperture diameter while maintaining high zoom magnification capability
Solution Approach 2:
Different lens groups are assigned different movement characteristics and functional roles. The first lens group is designed for large movement to achieve zoom, while the second lens group and subsequent groups are positioned to minimize movement and control light flux locally. This local optimization reduces the overall lens diameter requirement while maintaining zoom performance
3Adaptability or versatility
If the change in on-axis light flux during zooming is large, then the zoom lens can achieve high magnification, but the lens diameter becomes large
Solution Approach 1:
The patent implements a dynamic light flux control mechanism where the first lens group's large movement is compensated by the positioning of the second lens group and subsequent groups. This allows the on-axis light flux to be maintained within acceptable limits during zooming, reducing the required lens diameter while achieving high magnification ratios
Solution Approach 2:
The second lens group and subsequent groups act as intermediaries that mediate between the large movement of the first lens group and the image plane. These groups help control and stabilize the light flux path, preventing excessive changes in on-axis light flux that would otherwise require a larger lens diameter
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 achieves a compact zoom lens that can accommodate high-pixel image sensors while maintaining excellent optical performance across the zoom range.
Implementation Method 1
a first lens group having negative refractive power and a subsequent group in order from an object side to an image side. The subsequent group includes, in order from an object side to an image side, a Gp1 group including one or more lens groups and having positive refractive power as a whole, a Gn1 group including one or more lens groups and having negative refractive power as a whole
Data Source
AI summary
A zoom lens includes: a first lens group having negative refractive power and a subsequent group in order from an object side to an image side. The subsequent group includes, in order from an object side to an image side, a Gp1 group including one or more lens groups and having positive refractive power as a whole, a Gn1 group including one or more lens groups and having negative refractive power as a whole, a Gp2 group including one or more lens groups and having positive refractive power as a whole, and a Gn2 group including one or more lens groups and having negative refractive power as a whole. An aperture diaphragm is disposed closer to an object side than the Gp2 group, an interval between adjacent lens groups changes at least during one of zooming and focusing, and a predetermined expression is satisfied.