Compact Zoom Lens Design with Aperture Stop Segmentation
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving a balance between image quality and portability, as larger image pickup surface areas require larger lenses, and existing designs struggle to maintain image quality while minimizing size.
Innovation Solution
A zoom lens configuration comprising a first positive lens unit, a first negative lens unit, a second negative lens unit, and a second positive lens unit, with specific refractive power arrangements and conditional expressions to optimize lens thickness and aperture stop placement, allowing for a compact design while maintaining image quality across the zoom range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image pickup surface area is made large to improve image quality, then the zoom lens becomes large, but portability deteriorates
Solution Approach 1:
The zoom lens is divided into multiple lens units (first positive lens unit, first negative lens unit, second negative lens unit, and second positive lens unit) that can move independently relative to each other during zooming. This segmentation allows each unit to be optimized for specific functions, enabling compact overall design while maintaining image quality across the zoom range.
Solution Approach 2:
The distances between lens units are dynamically changed during zooming from wide angle end to telephoto end. Specifically, the distance between the first positive lens unit and the second negative lens unit widens more at the telephoto end than at the wide angle end, while other distances change in coordinated manner. This dynamic adjustment enables compact form factor while maintaining optical performance.
2Adaptability or versatility
If the zooming ratio is increased to improve versatility, then the lens complexity increases, but device complexity worsens
Solution Approach 1:
Each lens unit serves multiple functions: the first positive lens unit contributes to both wide angle and telephoto performance, the negative lens units enable compact zooming mechanism, and the second positive lens unit aids in focus and aberration correction. This multi-functionality allows achieving high zooming ratio with a relatively simple four-unit configuration rather than requiring many specialized elements.
3Volume of moving object
If the lens thickness is reduced to improve portability, then the refractive power becomes insufficient, but image quality deteriorates
Solution Approach 1:
Different lens units are assigned different refractive power characteristics optimized for their specific positions and functions. The first positive lens unit has positive refractive power for light convergence, the negative lens units have negative refractive power for beam expansion and compactness, and the second positive lens unit provides additional convergence. This localized optimization of refractive power in each unit enables sufficient total refractive power while keeping individual unit thicknesses minimal.
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 compact zoom lens with a high zooming ratio and wide angle of view, achieving improved image quality and portability by reducing off-axis aberrations and curvature of field, while ensuring sufficient refractive power and minimizing lens thickness.
Implementation Method 1
a first positive lens unit having a positive refractive power, a first negative lens unit having a negative refractive power, a second negative lens unit having a negative refractive power, and a second positive lens unit
Data Source
AI summary
A zoom lens comprises four lens unit, and at the time of zooming, each of a distance between a first positive lens unit and a first negative lens unit and a distance between a second negative lens unit and a second positive lens unit changes, and a distance between the first positive lens unit and the second negative lens unit widens more at the telephoto end than at the wide angle end, and the first positive lens unit includes an object-side sub-lens unit and an image-side sub-lens unit, and an aperture stop is disposed between the object-side sub-lens unit and the image-side sub-lens unit, and the first negative lens unit includes a negative lens and a positive lens, and a refracting surface nearest to an image in the first negative lens unit is concave toward the image side, and a refracting surface nearest to an object in the second positive lens unit is concave toward the object side, and a refracting surface nearest to the image in the second positive lens unit is convex toward the image side, and the zoom lens satisfies predetermined conditional expressions.