Zoom Lens First Unit Segmentation for Compact High Zoom Ratio
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Solution Overview
Problem
Current zoom lenses face challenges in achieving a balance between a wide angle of view, high zoom ratio, and compact size, while maintaining high optical performance and minimizing chromatic aberration, especially when used in high-resolution image pickup apparatuses like 4K and 8K cameras.
Innovation Solution
The zoom lens design includes a first lens unit with positive refractive power that does not move for zooming, multiple intermediate lens units that move, and a rear lens unit with positive refractive power, where the interval between adjacent lens units changes during zooming. This configuration satisfies specific inequalities to optimize the retrofocus ratio, focal length ratios, and aberration control, allowing for a compact and high-performance lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the angle of view or zoom ratio is increased, then the optical performance is improved, but the diameter of the first lens unit increases, resulting in an increase in size of the zoom lens
Solution Approach 1:
The first lens unit is divided into three lens subunits (first, second, and third) with different refractive powers. The first lens subunit has negative refractive power, the second has positive refractive power and moves for focusing, and the third has positive refractive power. This segmentation allows each subunit to be optimized independently, enabling high zoom ratios and wide angles of view while controlling the overall diameter of the first lens unit.
2Adaptability or versatility
If the zoom ratio is increased, then the versatility is improved, but the complexity of the lens structure increases
Solution Approach 1:
The patent employs two or more movable lens units that move in zooming, in addition to the focusing movement of the second lens subunit. The intervals between adjacent lens units change dynamically during zooming operations. This dynamic configuration enables high zoom ratios while maintaining a manageable structural complexity through optimized movement mechanisms.
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 design enables a zoom lens with a wide angle of view, high zoom ratio, and reduced size and weight, while maintaining high optical performance and controlling aberrations, making it suitable for high-resolution image capture applications.
Implementation Method 1
a first lens unit with a positive refractive power, which does not move for variation of magnification
Implementation Method 2
a plurality of movable lens units, which moves in variation of magnification, and a rear lens unit with a positive refractive power, such as that discussed in Japanese Patent Application Laid-Open No. 2015-161693
Implementation Method 3
a second lens subunit with a positive refractive power and configured to move for focusing
Data Source
AI summary
A zoom lens includes, from an object side a first lens unit (a positive refractive power) configured not to move for zooming, two or more intermediate lens units configured to move in zooming, and a rear lens unit (a positive refractive power), wherein an interval between each pair of adjacent lens units changes in zooming, the first lens unit includes, from the object side, a first lens subunit (a negative refractive power) configured not to move for focusing, a second lens subunit (a positive refractive power) configured to move for focusing, and a third lens subunit (a positive refractive power), the zoom lens satisfies specific inequalities concerning a focal length of the first lens unit, a length on an optical axis from a last surface to a rear principal point of the first lens unit, and a focal length of the zoom lens at a telephoto end.