Zoom Lens Subunit Movement for Close Distance Focusing
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Solution Overview
Problem
Existing zoom lenses for image pickup apparatuses face challenges in achieving a wide image pickup angle, high resolution, and small size while maintaining optical performance from infinity to close distances, particularly in focusing at minimum object distances without compromising mechanical complexity or image quality.
Innovation Solution
A zoom lens configuration with multiple lens units, including a first lens unit with negative refractive power, a first lens subunit with positive refractive power, and a second lens subunit with negative refractive power, where the first lens subunit moves towards the object side and the second lens subunit moves towards the image side during focusing from infinity to minimum object distance, satisfying specific movement and focal length inequalities to ensure optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floating system is adopted over the entire zoom range to maintain optical performance from infinity to close distance, then optical performance is improved, but device complexity increases
Solution Approach 1:
The patent divides the lens system into multiple lens units (first lens unit with negative refractive power, first lens subunit with positive refractive power, and second lens subunit with negative refractive power) that can move independently along different loci during focusing. This segmentation allows each subunit to be optimized for specific focusing ranges while reducing the overall mechanical complexity compared to a single floating system covering the entire zoom range.
Solution Approach 2:
The patent implements dynamic focusing by allowing the first lens subunit and second lens subunit to move along different loci during focusing from infinity to minimum object distance. The first lens subunit moves toward the object side while the second lens subunit moves toward the image side, enabling close distance focusing while maintaining optical performance without requiring a complex floating system across the entire zoom range.
2Volume of moving object
If the zoom lens is designed to achieve wide angle of view and small size, then compactness is improved, but close distance focusing capability deteriorates
Solution Approach 1:
The patent enables close distance focusing in a compact zoom lens by implementing dynamic movement of lens subunits. The first lens subunit moves toward the object side and the second lens subunit moves toward the image side during focusing, allowing the lens to achieve minimum object distance focusing while maintaining a small overall system size and wide angle of view capability.
Solution Approach 2:
The patent utilizes specific movement amount parameters (mA for the first lens subunit and mB for the second lens subunit) and focal length parameters (ft at telephoto end) to optimize the focusing capability. By controlling the movement amounts within specific ranges defined by the inequality 0.20(mB−mA)/ft≤1.00, the lens achieves close distance focusing while maintaining compact dimensions.
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 a zoom lens with reduced close distance and increased maximum image pickup magnification over the entire zoom range, while maintaining high optical performance and simplifying mechanical mechanisms, enabling effective focusing at close distances without significant aberration variations.
Implementation Method 1
a first lens unit having a negative refractive power; a first lens subunit having a positive refractive power; and a second lens subunit having a negative refractive power
Implementation Method 2
lens units, in which an interval between each pair of adjacent lens units is changed during zooming
Data Source
AI summary
Provided is a zoom lens, which includes lens units, in which an interval between each pair of adjacent lens units is changed during zooming, the zoom lens including, in order from an object side to an image side: a first lens unit having a negative refractive power; a first lens subunit having a positive refractive power; and a second lens subunit having a negative refractive power. During focusing from infinity to minimum object distance, the first lens subunit is moved toward the object side, and the second lens subunit is moved toward the image side. Further, a movement amount of the first lens subunit during focusing from infinity to minimum object distance at a telephoto end, a movement amount of the second lens subunit during focusing from infinity to minimum object distance at the telephoto end, and a focal length at the telephoto end are appropriately set.