Zoom Lens Compactness via Fourth Group Two-Stage Movement
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Solution Overview
Problem
There is a demand for compact zoom lenses with high optical performance that can achieve a high zoom ratio while maintaining compactness, which existing zoom lenses have not effectively addressed.
Innovation Solution
A zoom lens configuration comprising 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 with positive refractive power, where the distances between lens groups change during zooming, and the fourth lens group moves to the image side after initially moving to the object side, with specific focal length and refractive index conditions to optimize optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional zoom lens configurations are used to achieve high zoom ratio, then the zoom ratio increases, but the total length of the lens increases
Solution Approach 1:
The patent implements a dynamic zoom mechanism where the fourth lens group moves to the image side after initially moving to the object side during zooming. This two-stage movement pattern enables the lens to achieve high zoom ratio (0.40f1/ft < 0.80) while maintaining compact total length (TLt/(fw*ft)1/2 < 3.50) by optimizing the trajectory and positioning of movable lens groups throughout the zoom range.
2Adaptability or versatility
If the fourth lens group moves only in one direction during zooming, then the structure is simpler, but the zoom ratio and optical performance are limited
Solution Approach 1:
The patent divides the zooming process into distinct stages by segmenting the movement of the fourth lens group into two phases: first moving toward the object side, then moving toward the image side. This segmented movement strategy allows independent optimization of each phase's contribution to focal length adjustment, achieving high zoom ratio while maintaining manageable structural complexity through controlled multi-directional motion.
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 results in a compact zoom lens with excellent optical performance and a high zoom ratio, effectively addressing the need for downsizing while maintaining optical quality by optimizing the focal lengths and refractive indices of the lens groups.
Implementation Method 1
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
Data Source
AI summary
A zoom lens includes, in order from the object side: a first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, and a fourth lens group (G4) having positive refractive power. Upon zooming from the wide angle end state to the telephoto end state, the interval between each lens group changes and the fourth lens group (G4) moves to the image side after having once moved to the object side. The third lens group (G3) has, in order from the object side, a positive lens, a positive lens, and a negative lens. The zoom lens satisfies the following conditional expression: 2.50<TLt/(fw*ft)1/2<3.30, where TLt is the total length of the zoom lens in the telephoto state, fw is the focal distance of the total zoom lens system in the wide angle state, and ft is the focal distance of the total zoom lens system in the telephoto state.