Zoom Lens with Prism for Compact High-Performance Imaging
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving miniaturization while maintaining high performance and image quality, particularly in small-sized devices like cellular phones and digital still cameras, due to the need for space to move lens groups for magnification and focusing, and the demand for effective aberration correction.
Innovation Solution
A zoom lens configuration with a first lens group having negative refractive power, a second lens group composed of a positive and negative lens, and a third lens group with positive refractive power, where the second lens group moves concavely and the third lens group moves linearly, minimizing space requirements and using a light path changing member like a prism to reduce thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple lens groups are moved for magnification and focusing, then imaging performance is improved, but the whole length of the zoom lens increases
Solution Approach 1:
The zoom lens is divided into multiple lens groups (first through fourth lens groups) with different refractive powers, where only specific groups (second and third) are moved for magnification and focusing. This segmentation allows imaging performance to be maintained through selective movement while reducing the overall movement space required compared to moving all lens groups.
Solution Approach 2:
The patent employs a bent-type optical path configuration using a light path changing member (prism) to fold the optical path at approximately right angles. This transforms the linear optical path into a two-dimensional layout, reducing the whole length of the zoom lens in the direction of the optical axis while maintaining the necessary space for lens group movement.
2Length of moving object
If a light path changing member is used to reduce thickness, then miniaturization is improved, but optical path complexity increases
Solution Approach 1:
A light path changing member (prism) is introduced as an intermediary element to fold the optical path at approximately right angles. This prism serves as a mediator that redirects light between lens groups, enabling compact thickness reduction while maintaining clear optical path management through its positioned arrangement between the first and second lens groups.
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 allows for high-performance image quality with reduced thickness and aberration correction, achieving both miniaturization and satisfactory image formation across the entire magnification range.
Implementation Method 1
a light path changing member that changes a traveling direction of an incident light
Implementation Method 2
a first lens group having negative refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power
Data Source
AI summary
A zoom lens includes a first lens group G1 that is negative, a second lens group G2 that is negative, and a third lens group G3 that is positive. The first lens group G1 includes a first lens L1 that is negative and a prism P, and the second lens group G2 includes a second lens L2 that is positive and a third lens L3 that is negative. The third lens group G3 includes a stop ST, a fourth lens L4 that is positive, and a fifth lens L5 that is negative. According to this configuration, upon changing magnification from a wide-angle end to a telephoto end, the first lens group G1 is secured, the second lens group G2 first moves to the image plane side and then moves to the object side, and the third lens group G3 linearly moves to the object side.