Zoom Lens Diaphragm Positioning for Compact Wide-Angle Design
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Solution Overview
Problem
Existing zoom lenses with high zoom ratios and wide angles face challenges in achieving a balance between optical performance, size, and weight, particularly in setting the diaphragm position and focal length of lens units, leading to increased lens diameter and difficulty in maintaining good imaging performance across the entire zoom range.
Innovation Solution
A zoom lens configuration with a first lens unit having positive refractive power that does not move during zooming, and subsequent units including a moving positive lens unit and a diaphragm that moves, where the diaphragm is positioned closer to the object side at the wide-angle end than at the telephoto end, satisfying the condition 0.01≤Lwt/Td≤0.25, to maintain a compact size and high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the lens diameter of the first lens unit is increased to achieve a wider angle of view, then the angle of view is improved, but the zoom lens becomes larger
Solution Approach 1:
The patent applies dynamics by making the diaphragm movable during zooming rather than fixed. The diaphragm moves to different positions along the optical axis depending on the zoom setting, allowing the first lens unit to maintain a smaller diameter while still achieving wide angle of view at the wide-angle end. This dynamic adjustment resolves the contradiction by enabling angle of view variation without proportionally increasing lens diameter.
Solution Approach 2:
The patent changes the parameter of diaphragm position dynamically during zooming. By adjusting the diaphragm's axial position according to the zoom ratio, the system can optimize the effective aperture and ray heights for different focal lengths, allowing wide angle of view with a smaller first lens unit diameter than would be required with a fixed diaphragm configuration.
2Adaptability or versatility
If the focal length of the first lens unit is shortened to achieve a wider angle of view, then the angle of view is improved, but it becomes difficult to achieve good optical performance
Solution Approach 1:
The movable diaphragm allows the system to dynamically optimize optical performance across different zoom settings. At the wide-angle end, the diaphragm is positioned to control off-axis rays effectively, maintaining good peripheral imaging performance even with a shorter focal length first lens unit. This dynamic control compensates for the optical performance degradation that would normally result from shortening the focal length.
Solution Approach 2:
By changing the diaphragm position parameter during zooming, the system can maintain optimal f-ratios and ray control for different focal lengths. This allows the first lens unit to have a shorter focal length for wide angle of view while the movable diaphragm adjusts to maintain proper illumination and reduce aberrations, thereby preserving optical performance.
3Reliability
If the lens unit including the diaphragm has three or more lenses to maintain optical performance, then optical performance is improved, but the size and weight increase
Solution Approach 1:
The movable diaphragm provides an additional degree of freedom for optical optimization without adding lens elements. By dynamically adjusting the diaphragm position, the system can achieve good optical performance with fewer lenses in the diaphragm unit, thereby reducing weight while maintaining reliability through dynamic control rather than static optical complexity.
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 zoom lens with a wide angle of view, small size, and light weight, while maintaining high optical performance across the entire zoom range by optimizing the movement of lens units and diaphragm position, thus addressing the challenges of lens diameter and imaging performance.
Implementation Method 1
a first lens unit having a positive refractive power
Implementation Method 2
a moving positive lens unit consisting of one or two lenses, having a positive refractive power, and configured to move in zooming
Implementation Method 3
a diaphragm configured to move in zooming. The diaphragm is closer to the object side at the wide-angle end than at the telephoto end
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, and a subsequent unit including a plurality of lens units, The first lens unit is configured not to move for zooming. A distance between each pair of adjacent lens units changes in zooming. The subsequent unit includes, in order from the image side to the object side, a lens having a positive refractive power and configured not to move for zooming, a moving positive lens unit consisting of one or two lenses, having a positive refractive power, and configured to move in zooming, and a diaphragm configured to move in zooming. The diaphragm is closer to the object side at the wide-angle end than at the telephoto end. A predetermined condition is satisfied.