Zooming Optical System with Single-Lens Autofocus Group
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Solution Overview
Problem
Conventional zooming optical systems face challenges in achieving high optical performance while downsizing and speeding up autofocusing.
Innovation Solution
A zooming optical system configuration that includes a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group, where the distances between these groups are varied during zooming, and the third lens group moves along the optical axis for focusing, composed of a single positive lens to enhance optical performance and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional zooming optical system configuration is used, then optical performance can be maintained, but the system size cannot be reduced and autofocusing speed is insufficient
Solution Approach 1:
The optical system is divided into four distinct lens groups (G1, G2, G3, G4) with specific refractive power configurations. The third lens group G3 is further segmented to be a single positive lens, which can be independently moved for focusing operations. This segmentation allows each group to have optimized functions while reducing overall system complexity and size.
Solution Approach 2:
The patent implements dynamic zooming by varying distances between lens groups during zooming operations. Specifically, the distance between G1-G2, G2-G3, and G3-G4 are all varied during zooming from wide-angle to telephoto end. Additionally, the third lens group G3 is designed to move dynamically along the optical axis for focusing from infinite to near-distance objects, enabling fast autofocusing.
2Reliability
If the third lens group is composed of multiple lenses, then optical performance can be improved, but the system size increases and focusing speed decreases
Solution Approach 1:
The patent extracts the focusing function from a complex multi-lens third lens group and implements it using a single positive lens. This extraction simplifies the third lens group G3 while maintaining its ability to correct aberrations and enable fast focusing by moving along the optical axis.
Solution Approach 2:
The patent changes the structural parameter of the third lens group from multiple lenses to a single positive lens. This parameter change reduces the mass and complexity of the focusing group, thereby increasing autofocusing speed while maintaining optical performance through proper positioning and refractive power design.
3Length of moving object
If lens groups are positioned closer together, then system size is reduced, but optical performance deteriorates due to increased aberrations
Solution Approach 1:
The patent applies local quality by assigning specific refractive power characteristics to each lens group: G1 has positive refractive power, G2 has negative refractive power, and G3 has positive refractive power. This alternating pattern of refractive powers allows each group to contribute differently to aberration correction, enabling compact positioning while maintaining optical performance.
Solution Approach 2:
The patent converts the potential harm of compact lens positioning (which increases aberrations) into a benefit by using the negative refractive power of G2 and positive refractive power of G3 to actively correct aberrations introduced by the compact configuration. The specific arrangement transforms the challenge of small size into an opportunity for optimized aberration correction.
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 configuration enables high optical performance with downsized optics and accelerated autofocusing, effectively correcting aberrations and reducing the lens barrel's outer diameter.
Implementation Method 1
a third lens group having positive refractive power; and a fourth lens group having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the fourth lens group being varied; the third lens group being composed of one positive lens; and focusing from an infinite-distance object up to a near-distance object being conducted by moving the third lens group in a direction of the optical axis
Data Source
AI summary
A zooming optical system includes, in order from an object side along an optical axis: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group is varied, a distance between the second lens group and the third lens group is varied, and a distance between the third lens group and the fourth lens group is varied; the third lens group is composed of one positive lens; and a focus from an infinite-distance object up to a near-distance object is conducted by moving the third lens group in a direction of the optical axis.