Zoom Lens Hand Shake Correction via Partial Group Shifting
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Solution Overview
Problem
Existing zoom lenses face challenges in effectively correcting hand shake-induced image blur across the entire zoom range while minimizing the size of the barrel and driving mechanism, particularly at the telephoto end where small hand shake angles result in large image blur and increased aberration fluctuations.
Innovation Solution
A zoom lens configuration with specific focal length ratios and refractive power distributions among lens groups, including a final lens group with a negative and positive refractive power, and a second lens group with aspheric surfaces, allows for effective hand shake correction up to 1.0° across the zoom range, minimizing barrel size and aberration fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the third lens group is shifted for hand shake correction, then the shake correction coefficient is improved, but fluctuation in aberrations increases and the correctable angle is limited to about 0.5°
Solution Approach 1:
The final lens group is divided into three partial lens groups (G51, G52, G53) with different refractive powers. The second partial lens group (G52) with positive refractive power is specifically selected for shift operations during hand shake correction, while the other partial groups remain stationary. This segmentation allows optimized correction performance with reduced aberration fluctuations compared to shifting the entire third lens group.
2Measurement precision
If a part or the whole of the final lens group is shifted to correct hand shake, then the rays pass through with small diameter reducing sensitivity to eccentricity, but the shift amount in telephoto end state extremely increases requiring larger outer diameter and thickness
Solution Approach 1:
The second partial lens group (G52) is designed with specific optical properties (positive refractive power and specific focal length relationship) that optimize the balance between correction effectiveness and shift amount. By positioning G52 within the final lens group and giving it specific refractive characteristics, the patent achieves reduced eccentricity sensitivity while maintaining manageable shift amounts even in telephoto end state.
3Adaptability or versatility
If the shift lens group is designed with sufficient effective diameter to correct hand shake angle of 1.0°, then the correction capability is improved, but the outer diameter and thickness extremely increase causing the driving mechanism to increase in size
Solution Approach 1:
The patent optimizes the focal length of the second partial lens group (fG52) relative to the focal length of the final lens group (fG5) by establishing the conditional expression 0.05 < fG52/fG5 < 0.30. This parameter optimization enables the lens group to achieve sufficient correction capability for 1.0° hand shake angles while maintaining a compact size that prevents excessive growth of the driving mechanism.
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 enables comprehensive hand shake correction and maintains excellent imaging performance by satisfying specific conditional expressions for focal length ratios and refractive power distributions, ensuring effective aberration correction and miniaturization of the driving mechanism.
Implementation Method 1
shift a partial lens group constituting a lens system in a direction substantially perpendicular to the optical axis so as to shift image position and correct fluctuation in aberrations
Implementation Method 2
a zoom lens which optically corrects image blur caused by hand shake and the like
Data Source
AI summary
Provided is a zoom lens that has a plurality of lens groups and performs zooming by changing spaces between the plurality of lens groups. A final lens group closest to an image side includes, in order from an object side to an image side: a first partial lens group that has a negative refractive power; a second partial lens group that has a positive refractive power; and a third partial lens group that has a positive refractive power. Image blur is corrected by shifting the second partial lens group in a direction substantially perpendicular to an optical axis. Assuming that a focal length of the first partial lens group is fGF, a focal length of the second partial lens group is fGS, and a focal length of a whole lens system of the lens groups in a telephoto end state is ft, the following expressions are satisfied: −0.24<fGF/ft<−0.09; and 0.12<fGS/ft<0.32.