Zoom Lens Image Stabilization Using Positive Refractive Power
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a high zoom ratio and maintaining high optical performance over the entire zoom range while ensuring image stabilization, particularly due to difficulties in precisely moving lens units with negative refractive power and increasing system size.
Innovation Solution
A zoom lens configuration with a first positive refractive power unit, a second negative refractive power unit, a third positive refractive power unit, a fourth positive refractive power unit, and a fifth negative refractive power unit, where the third unit moves towards the object side during zooming and the fourth unit moves vertically during image stabilization, with specific focal length and curvature radius conditions to optimize refractive power distribution and reduce system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lens unit with negative refractive power is used for image stabilization, then image blur correction capability is improved, but image stabilization sensitivity increases excessively with zoom ratio making precise movement difficult
Solution Approach 1:
Instead of using a lens unit with negative refractive power for image stabilization as in conventional designs, this patent inverts the approach by using a lens unit with positive refractive power (the fourth lens unit) for image stabilization. This inversion resolves the problem of excessively high stabilization sensitivity that occurs with negative power units at high zoom ratios, enabling more precise and controllable movement for blur correction.
2Ease of manufacture
If a lens unit with negative refractive power is divided into two lens sub units to reduce image stabilization sensitivity, then stabilization sensitivity is reduced, but lens unit thickness increases making it difficult to secure movement space
Solution Approach 1:
Rather than dividing a negative power lens unit into sub-units to reduce sensitivity, this patent inverts the approach by selecting a positive power lens unit (fourth lens unit) for image stabilization. This eliminates the need for subdivision while maintaining appropriate sensitivity levels and preserving sufficient movement space within the lens structure.
3Reliability
If the fourth lens unit with positive refractive power is used for image stabilization, then high optical performance is maintained during stabilization, but the lens unit must be moved precisely
Solution Approach 1:
This patent uses a positive power lens unit (fourth lens unit) for image stabilization instead of the conventional negative power unit, which inverts the traditional approach. This inversion maintains high optical performance during stabilization while the positive power characteristics enable more predictable and controllable movement behavior, improving manufacturability despite the precision requirements.
Solution Approach 2:
The patent carefully controls the refractive power parameter of the fourth lens unit by satisfying specific conditional expressions (1.05 < f4/f3 < 2.00 and 0.30 < f4/fw < 0.80). This parameter optimization ensures that the lens unit has appropriate movement characteristics for precise control during image stabilization while maintaining high optical performance.
4Volume of moving object
If the zoom lens is designed to be compact with high zoom ratio, then system size is reduced, but it becomes difficult to maintain high optical performance over the entire zoom range
Solution Approach 1:
The patent optimizes multiple parameters including the refractive power ratios (f4/f3, f4/fw), curvature radii of lens surfaces, and spacing between lens units. These parameter changes enable the compact lens design to maintain high optical performance across the entire zoom range by carefully balancing the optical contributions of each lens unit.
Solution Approach 2:
The patent employs dynamic movement of multiple lens units during zooming operations. The third lens unit moves toward the object side during zooming, while intervals between adjacent lens units are changed dynamically. This dynamic configuration allows the compact lens to maintain optimal optical performance throughout the zoom range despite the reduced system size.
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 high zoom ratio while maintaining high optical performance and reducing the system's size, effectively correcting image blur and stabilizing images across the zoom range without increasing the system's size or requiring excessive lens movement.
Implementation Method 1
the fourth lens unit is configured to move in a direction having a vertical component with respect to an optical axis during image stabilization
Implementation Method 2
a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; a fourth lens unit having a positive refractive power; and a fifth lens unit having a negative refractive power
Data Source
AI summary
Provided is a zoom lens, including, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; a fourth lens unit having a positive refractive power; a fifth lens unit having a negative refractive power; and a rear lens group including one or more lens units, in which the third lens unit is configured to move toward the object side during zooming from a wide angle end to a telephoto end, in which an interval between adjacent lens units is changed during zooming, in which the fourth lens unit is moved in a direction having a vertical component to an optical axis during image stabilization, and in which focal lengths of the third and fourth lens units are appropriately set.