Compact Zoom Lens System with Dual-Function Third Unit
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Solution Overview
Problem
Existing zoom lens systems face challenges in reducing their overall length while maintaining excellent optical performance, leading to increased size and weight of the lens barrel.
Innovation Solution
A zoom lens system with a four-unit construction of negative, positive, negative, and positive optical power, where the first and third lens units move along the optical axis, and the fourth lens unit is fixed, satisfying specific conditions to achieve compactness and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lens units are made movable to contribute to both focusing and zooming functions, then optical performance is improved, but the overall length of the lens system increases
Solution Approach 1:
The third lens unit is designed to perform dual functions: it moves along the optical axis during zooming (contributing to focal length change) and also moves during focusing from infinity to close-object conditions. This multi-functionality allows a single lens unit to replace what would traditionally require separate mechanisms, thereby improving optical performance while controlling the overall length of the lens system.
2Reliability
If lens units are made movable to contribute to focusing and zooming, then optical performance is improved, but the lens barrel size increases
Solution Approach 1:
By making the third lens unit capable of performing both focusing and zooming operations through its movement along the optical axis, the patent reduces the need for additional dedicated lens units or mechanisms. This consolidation decreases the overall complexity and volume requirements of the lens barrel, allowing for a more compact design that maintains excellent optical performance.
3Length of moving object
If the third lens unit moves along the optical axis for both zooming and focusing, then the lens system becomes more compact, but the mechanism complexity increases
Solution Approach 1:
The patent divides the lens system into four distinct lens units with specific optical power assignments (negative, positive, negative, positive). The third lens unit is specifically designated to handle both focusing and zooming movements. This segmentation allows for a structured approach where each unit has a defined role, making the overall mechanism more manageable and easier to implement despite the dual-function requirement.
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 and lightweight zoom lens system with reduced overall length, enabling a smaller lens barrel and improved optical performance, while preventing dust entry and simplifying the lens barrel configuration.
Implementation Method 1
a zoom lens system, in order from an object side to an image side, comprising a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(c)
Figure 3(a)~3(c)
AI summary
A zoom lens system comprising a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, wherein the first lens unit and the third lens unit move along an optical axis, and the fourth lens unit is fixed with respect to an image surface, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the third lens unit moves along the optical axis, in focusing from an infinity in-focus condition to a close-object in-focus condition, and the conditions: 0.0 < |M3/fW| < 0.5 and 0.2 < |f3/f4| < 1.0 (M3: an amount of movement of the third lens unit in zooming, f3: a composite focal length of the third lens unit, f4: a composite focal length of the fourth lens unit, fW: a focal length of the entire system at a wide-angle limit) are satisfied; an interchangeable lens apparatus; and a camera system.