Zoom Lens Compact Design with Vibration Reduction Subgroups
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Solution Overview
Problem
Telephoto type zoom lenses face challenges in reducing total optical length while maintaining long focal lengths and incorporating vibration reduction and focusing lens groups with small diameters for improved optical performance, especially in remote surveillance applications where image blurring from vibrations and weather conditions is a concern.
Innovation Solution
A zoom lens configuration comprising a first positive refractive power lens group, a second negative refractive power lens group, a third positive refractive power lens group, and a fourth negative refractive power lens group, where the fourth lens group includes sub-groups that move to correct image blur and focus, with specific conditional expressions to optimize refractive powers and lens movements for reduced size and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal length is increased on the telephoto side, then the optical performance is improved, but the total optical length increases
Solution Approach 1:
The fourth lens group is divided into five sub-groups (G4A, G4B, G4C, G4D, G4E) with different functions. The G4B sub-group is dedicated to vibration reduction and G4D to focusing, allowing independent optimization of each function while maintaining compact overall length.
Solution Approach 2:
The lens groups are designed with dynamic movement capabilities: G2 and G3 move during zooming, G4B moves perpendicular to the optical axis for vibration reduction, and G4D moves along the optical axis for focusing. This dynamic design allows compact structure while maintaining long focal length performance.
2Reliability
If a vibration reduction lens group is added, then image blur correction capability is improved, but the device complexity increases
Solution Approach 1:
The fourth lens group serves multiple functions: G4A and G4C contribute to the overall negative refractive power of the fourth lens group, G4B provides vibration reduction, and G4D provides focusing. This multi-functional design reduces overall device complexity by combining multiple functions within a single lens group structure.
3Productivity
If a focusing lens group with small diameter is used, then the autofocus speed is improved, but the optical performance may deteriorate
Solution Approach 1:
The G4D focusing lens group is designed with specific local optical properties (negative refractive power and particular focal length) that are optimized for its focusing function. This local optimization allows the small-diameter focusing group to maintain high optical performance while achieving fast autofocus speed.
4Adaptability or versatility
If the fourth lens group is configured with multiple sub-groups for vibration reduction and focusing, then the functionality is improved, but the manufacturing complexity increases
Solution Approach 1:
The fourth lens group is segmented into five functional sub-groups, each with specific roles. This segmentation allows independent optimization and manufacturing of each sub-group according to its specific functional requirements, thereby managing manufacturing complexity while enhancing overall functionality.
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 reduces the total optical length while achieving long focal lengths on the telephoto side, incorporating a vibration reduction lens group and a focusing lens group with small diameters, thereby enhancing optical performance and correcting image blurring caused by vibrations and weather conditions.
Implementation Method 1
a fourth B lens group which has a negative refractive power and which moves in a direction intersecting with an optical axis during image blur correction
Implementation Method 2
a fourth D lens group which has a negative refractive power and which moves along the optical axis during focusing
Implementation Method 3
a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a third lens group that has a positive refractive power; and a fourth lens group that has a negative refractive power
Data Source
AI summary
The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a stop, and a negative fourth lens group. During zooming, the second and third lens groups move. The fourth lens group consists of, in order from the object side, a fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, and a negative fourth D lens group moving during focusing, and a positive fourth E lens group. The zoom lens satisfies predetermined conditional expressions.