Zoom Lens Cemented Fourth Group Compact Thickness
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Solution Overview
Problem
Existing zoom lenses with bending optical systems struggle to achieve a high variable power ratio and wide field angle while maintaining a thin camera thickness, often resulting in increased aberrations and reduced productivity due to complex lens group configurations and sensitivity to decentration errors.
Innovation Solution
A zoom lens configuration with a 5 or 6 lens group structure, including a first lens group with a reflective optical element and a fourth lens group composed of three cemented lenses with specific refractive index and Abbe number conditions, which simplifies the structure, reduces aberrations, and improves productivity by minimizing decentration errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a bending optical system with reflective optical element is used to reduce camera thickness, then the thickness in the optical axis direction is reduced, but the variable power ratio is limited to about 4 or 5
Solution Approach 1:
The lens system is divided into five distinct lens groups with specific refractive power characteristics. The fourth lens group is further segmented into three cemented lenses (positive, negative, and positive) to achieve precise control over the variable power ratio while maintaining compact thickness. This segmentation allows the system to achieve a variable power ratio of about 6 or more while keeping the camera thickness reduced.
2Device complexity
If the fourth lens group is composed of three separate lenses without cementing, then the structure is simpler, but lens decentration error and distance error between lenses increase
Solution Approach 1:
The third, fourth, and fifth lenses are cemented together to form a single fourth lens group unit. This merging reduces the number of separate components that need to be precisely positioned and aligned. By cementing these lenses, the system maintains structural simplicity while significantly reducing lens decentration errors and inter-lens distance variations, thereby improving manufacturing precision without requiring extremely tight tolerances on individual lens alignment.
3Length of stationary object
If the fourth lens group thickness is reduced to achieve compact structure, then the overall camera thickness is reduced, but lens element decentration error sensitivity increases
Solution Approach 1:
By cementing the third, fourth, and fifth lenses into a single fourth lens group, the system reduces the cumulative effect of decentration errors that would occur with separate lenses. The cemented structure acts as a unified unit, maintaining compact thickness while reducing sensitivity to manufacturing tolerances and alignment errors, thereby improving reliability without sacrificing compactness.
4Adaptability or versatility
If a 6 group configuration is used to increase variable power ratio, then the variable power ratio reaches about 5, but the device complexity increases
Solution Approach 1:
The patent consolidates three lenses (positive, negative, and positive) into a single fourth lens group through cementing. This merging approach achieves a variable power ratio of about 6 or more while maintaining a manageable 5-group configuration rather than a more complex 6-group configuration. The cemented structure reduces the number of separate components that need to be independently controlled, thereby reducing overall device complexity while achieving high variable power ratio.
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 proposed configuration achieves a high variable power ratio and wide field angle while maintaining a compact camera thickness, effectively correcting aberrations and improving the accuracy and positioning of lens elements, thus enhancing the optical performance and reducing manufacturing errors.
Implementation Method 1
a bending optical system that bends an optical axis by 90 degrees by a reflective optical element (e.g., prism)
Implementation Method 2
a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power
Data Source
AI summary
A zoom lens including a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, in an order from an object; wherein a variable power from a wide angle end to a telephoto end is performed by changing distances among the respective lens groups, and the fourth lens group comprises a three cemented lens comprising a positive c1 lens, a negative c2 lens, and a positive c3 lens from an order from the object.