Five-Group Imaging Lens with Dual-Move Focus Mechanism
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Solution Overview
Problem
Existing imaging lenses for short-distance imaging suffer from defocus due to lens position errors and require larger size and weight, with significant variations in aberrations and sensitivity between focus groups, making them unsuitable for modern high-pixel cameras.
Innovation Solution
An imaging lens configuration with a specific arrangement of five lens groups, where the first lens group is immovable, and the second and fourth lens groups move along different trajectories during focus changes, satisfying certain conditional expressions to minimize defocus and aberration variations, while reducing the lens system's size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a five-group configuration with movable second and fourth lens groups is used for short-distance imaging, then imaging capability is improved, but defocus occurs due to lens position errors
Solution Approach 1:
The patent applies parameter changes by carefully selecting the focal lengths of the lens groups (f1, f2, f3, f4, f5) and their relative positions to satisfy specific conditional expressions. This optimization reduces the sensitivity of the optical system to position errors, thereby minimizing defocus while maintaining short-distance imaging capability.
Solution Approach 2:
The patent segments the optical system into five distinct lens groups with specific refractive power configurations (positive, negative, positive, positive, negative). This segmentation allows independent optimization of each group's function and movement characteristics, improving overall system performance while reducing defocus sensitivity.
2Adaptability or versatility
If the lens system is designed for short-distance imaging with high magnification, then imaging capability is improved, but the lens system size and weight increase
Solution Approach 1:
The patent optimizes the focal length parameters and refractive power distribution of the five lens groups to achieve short-distance imaging capability with reduced overall system size and weight. The conditional expressions constrain the parameters to values that minimize mass while maintaining optical performance.
3Adaptability or versatility
If the lens system is designed for short-distance imaging with high magnification, then imaging capability is improved, but aberrations are not satisfactorily corrected
Solution Approach 1:
The patent divides the optical system into five lens groups with alternating positive and negative refractive powers. This segmentation enables independent correction of different types of aberrations by each group, achieving satisfactory aberration correction across the entire system while maintaining short-distance imaging capability.
Solution Approach 2:
The patent carefully selects and constrains the focal length parameters, refractive powers, and relative positions of the lens groups through conditional expressions. These parameter optimizations ensure that aberrations are corrected while maintaining the desired short-distance imaging performance.
4Length of moving object
If the ratio of lens total length to back focus is reduced for compactness, then device size is improved, but focus sensitivity increases making the system more prone to defocus
Solution Approach 1:
The patent optimizes the ratio of lens total length to back focus by carefully selecting the focal lengths and positions of the five lens groups. The conditional expressions ensure that this ratio is constrained to values that achieve compactness while minimizing focus sensitivity and defocus occurrence.
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 effectively suppresses defocus and aberration variations, achieving high image quality and compactness, suitable for high-pixel cameras with reduced lens system size and weight.
Implementation Method 1
an imaging lens which includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power
Data Source
AI summary
The imaging lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power. In a case of changing focus from an object at infinity to an object at the closest distance, the first lens group is immovable, and the second lens group and the fourth lens group are moved in an optical axis direction along different trajectories from each other. In addition, predetermined conditional expressions (1) to (3) are satisfied.