Variable Magnification Lens Shake Correction via Second Group
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Solution Overview
Problem
Conventional variable magnification optical systems for compact digital cameras face challenges in providing sufficient aberration performance and camera-shake correction, particularly in compact designs where the first lens group's movement is difficult due to its weight and the degree of sensitivity to decentering is insufficient, leading to suboptimal image quality and increased complexity.
Innovation Solution
A variable magnification optical system with a power arrangement of 'negative, positive, negative, and positive' lens groups, where the second lens group moves in the in-surface direction perpendicular to the optical axis to correct camera shake, ensuring an appropriate degree of sensitivity to decentering by maintaining the first and fourth lens groups immobile, and adhering to the focal length and image height ratio within the range of 1.7 to 2.7, thereby optimizing aberration correction and system length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first lens group is moved for camera-shake correction, then camera-shake correction function is achieved, but the heavy weight of the first lens group increases device complexity and requires high-accuracy motor thrust and detection systems
Solution Approach 1:
The patent extracts the camera-shake correction function from the first lens group and assigns it to the second lens group. By separating the correction function from the heavy first lens group, the system achieves camera-shake correction without requiring high-accuracy motor thrust and detection systems for the heavy first lens group, thus reducing device complexity while maintaining correction reliability.
Solution Approach 2:
The patent applies local quality by making only the second lens group movable for camera-shake correction while keeping the first lens group fixed. This localized movement approach allows camera-shake correction to be achieved with smaller, less complex motors and detection systems, as only a portion of the optical system needs to be movable rather than the entire first lens group.
2Reliability
If the second lens group is moved for camera-shake correction, then camera-shake correction is achieved, but the degree of sensitivity to decentering becomes insufficient in compact designs with short back focus
Solution Approach 1:
The patent applies parameter changes by carefully controlling the back focus distance and the position of the second lens group. By optimizing these parameters, the system achieves appropriate sensitivity to decentering for compact designs with short back focus, ensuring that camera-shake correction remains effective while maintaining manufacturing precision requirements at acceptable levels.
3Device complexity
If the first lens group is made immobile, then device complexity is reduced, but aberration correction performance may deteriorate
Solution Approach 1:
The patent segments the optical system into multiple lens groups with distinct functions: the first lens group handles aberration correction while remaining fixed, and the second lens group handles camera-shake correction by moving. This segmentation allows each group to optimize its specific function independently, maintaining aberration correction performance while reducing overall device complexity.
Solution Approach 2:
The patent achieves multi-functionality by designing the second lens group to serve dual purposes: it contributes to aberration correction when fixed, and provides camera-shake correction when moved. This universal design allows the system to maintain aberration correction performance even with the first lens group immobile, as the second lens group compensates for the reduced degrees of freedom.
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 enables effective camera-shake correction with a compact design, reducing the need for high-accuracy motor thrust and detection systems, while maintaining high aberration correction capabilities, thus suitable for small-size image-taking apparatuses.
Implementation Method 1
the second lens group moves in an in-surface direction vertical to an optical axis direction to thereby correct shake resulting from imaging on the image surface
Data Source
AI summary
A variable magnification optical system including at least: a first lens group having a negative optical power, a second lens group having a positive optical power, a third lens group having a negative optical power, and a fourth lens group having a positive optical power moves the second lens group in an—in-surface direction vertical to the optical axis direction in zooming to thereby correct shake resulting from imaging on the image surface.