Zoom Lens Image Stabilization via Orthogonal Second Unit Movement
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Solution Overview
Problem
Existing zoom lenses face challenges in maintaining optical performance during image stabilization at the telephoto end due to strong refractive power of the second lens unit, which leads to manufacturing errors and size limitations, as well as insufficient correction of decentering aberration.
Innovation Solution
A zoom lens configuration with a first lens unit having positive refractive power and a second lens unit with negative refractive power that does not move during zooming, where the second lens unit is stabilized by moving in a direction orthogonal to the optical axis, and the structure is optimized to satisfy specific inequalities for maintaining image stabilizing performance and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second lens unit with strong refractive power is used as the image stabilizing unit, then image stabilization function is achieved, but optical performance deteriorates due to manufacturing errors
Solution Approach 1:
The second lens unit is divided into multiple lens elements (including a positive lens closest to the object and negative lenses) to distribute and balance the refractive power. This segmentation allows the unit to achieve both strong overall refractive power for image stabilization and individual element optimization to reduce sensitivity to manufacturing errors.
Solution Approach 2:
Different lens elements within the second lens unit are assigned specific refractive powers and positions (positive lens closest to object, followed by negative lenses) to optimize local optical properties. This local quality distribution enables the unit to maintain stability against manufacturing tolerances while achieving the required image stabilization performance.
2Adaptability or versatility
If more lenses are added to the second lens unit to achieve further telephoto scheme, then magnification is improved, but decentering aberration correction becomes insufficient
Solution Approach 1:
The second lens unit employs an asymmetric arrangement of lens elements with different refractive powers (positive lens closest to object, followed by negative lenses) rather than a symmetric configuration. This asymmetric design effectively corrects decentering aberrations that occur during image stabilization while enabling extended telephoto magnification capability.
3Adaptability or versatility
If the second lens unit moves during zooming, then zooming function is achieved, but the unit cannot be used for image stabilization
Solution Approach 1:
The lens system is designed with dynamic movement capabilities where the first and third lens units move during zooming to change focal length, while the second lens unit remains stationary during zooming but can move independently during image stabilization. This dynamic separation of functions allows both zooming and image stabilization to be achieved without interference.
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 achieves high optical performance and compact size with effective image stabilization at the telephoto end, reducing the impact of manufacturing errors and aberrations, while maintaining a lightweight design.
Implementation Method 1
a second lens unit having negative refractive power, and a rear group consisting of one or more lens units
Data Source
AI summary
A zoom lens includes a plurality of lens units, the plurality of lens units consisting of, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a rear group consisting of one or more lens units. A distance between adjacent lens units changes during zooming, and the second lens unit does not move for zooming. At least a part of the second lens unit moves in a direction including a component orthogonal to an optical axis during image stabilization. A lens disposed closest to an object in the second lens unit has positive refractive power. A predetermined inequality is satisfied.