Zoom Lens with Perpendicular Shifting Sub-Group
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving high power variation ratios while maintaining miniaturization and preventing performance degradation, particularly due to issues with off-axis aberrations and hand shake correction, which are exacerbated by high zoom ratios and the need for large lens diameters and complex driving mechanisms.
Innovation Solution
A zoom lens configuration with four lens groups, including a first positive, second negative, third positive, and fourth positive refracting power groups, where the second and fourth groups move to compensate for variations, and the third group's positive sub-group is shiftable perpendicular to the optical axis, with specific conditional expressions to optimize refracting powers and curvatures, ensuring effective aberration correction and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture ratio is increased to prevent noise, then the light receiving area is reduced, but the lens diameter increases and the structure becomes more complex
Solution Approach 1:
The third lens group is divided into a negative sub-group and a positive sub-group, with the positive sub-group being movable for hand shake correction. This segmentation allows the hand shake correction function to be implemented without requiring the entire lens system to be complex, isolating the correction mechanism to a specific subsystem.
Solution Approach 2:
The positive sub-group of the third lens group is given the specific property of being movable perpendicular to the optical axis, while other lens groups remain fixed. This localized mobility provides hand shake correction capability without requiring the entire lens system to be redesigned with complex mechanisms.
2Adaptability or versatility
If a high zoom ratio is achieved, then the power variation ratio increases, but off-axis aberrations worsen and the lens diameter increases
Solution Approach 1:
The positive sub-group of the third lens group is made dynamically movable perpendicular to the optical axis to correct hand shake and off-axis aberrations. This dynamic adjustment capability allows the lens to maintain image quality across the high zoom ratio range without requiring a larger lens diameter.
Solution Approach 2:
The focal length of the positive sub-group is specifically designed to satisfy the conditional expression |f3n|/f3 < 1.0, where f3n is the focal length of the negative sub-group and f3 is the focal length of the third lens group. This parameter optimization enables effective aberration correction while maintaining the high zoom ratio capability.
3Ease of operation
If the third lens group is shifted for hand shake correction, then the image shifting capability is improved, but the driving mechanism becomes more complex
Solution Approach 1:
Instead of shifting the entire third lens group, only the positive sub-group is made movable. This segmentation reduces the mass that needs to be driven, simplifying the driving mechanism while maintaining the hand shake correction capability.
Solution Approach 2:
The positive sub-group is given the specific function of hand shake correction through its ability to move perpendicular to the optical axis. This localized functional assignment simplifies the overall driving mechanism compared to shifting the entire lens group.
4Volume of moving object
If the lens system is miniaturized, then the camera size is reduced, but the light receiving area decreases causing more noise
Solution Approach 1:
The movable positive sub-group enables hand shake correction in a miniaturized lens system, allowing the use of smaller aperture ratios without excessive noise. The dynamic correction capability compensates for the reduced light gathering area, maintaining image quality in a compact form factor.
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 effectively suppresses performance degradation, achieves miniaturization, and corrects various aberrations, including coma and off-axis aberrations, while maintaining a high zoom ratio, thereby enhancing image quality and simplifying the lens barrel structure.
Implementation Method 1
a positive sub group having a positive refracting power... to shift an image in a direction substantially perpendicular to the optical axis
Data Source
AI summary
A zoom lens is disclosed which is superior in reduction of the lens diameter and can suppress degradation in performance while a high zoom ratio is achieved. The zoom lens is formed as a zoom lens of a four-group configuration having positive, negative, positive and positive groups. The second and fourth lens groups (G2, G4) move whereas the first and third lens groups (G1, G3) are fixed. An aperture stop (S) is disposed on the object side of the third lens group.(G3) The third lens group (G3) includes negative (L31) and positive (L32, L33) sub groups with an air distance left therebetween. The positive sub group (L32, L33) is shiftable perpendicularly to the optical axis (x) to shift an image substantially perpendicularly. A conditional expression 1.4 < |f3n|/f3 < 3 is satisfied where f3n is the focal distance of the negative sub group (L31) and f3 is the focal distance of the third lens group (G3).