Zoom Lens Compact Design Using Folded Optical Path
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses face challenges in achieving miniaturization while maintaining high performance and image quality, especially in small-sized devices like cellular phones and digital still cameras, due to the need for space to move lens groups for magnification and focusing, and the demand for wide-angle views and aberration correction.
Innovation Solution
A zoom lens configuration with a first lens group having positive and negative refractive powers, a second lens group composed of two lenses with negative refractive power, and a third lens group with positive refractive power, where the second lens group moves in a concave trajectory and the third lens group moves linearly, minimizing space requirements and using a light path changing member like a prism to reduce thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zoom lens is designed with multiple lens groups that move along the optical axis to enable magnification and focusing, then the imaging performance and aberration correction are improved, but the overall length of the zoom lens increases, making miniaturization difficult
Solution Approach 1:
The patent introduces a light path changing member (prism or mirror) that bends the optical path at approximately 90 degrees. This changes the light propagation from a straight line to a bent path, allowing the lens groups to be arranged in a folded configuration rather than extending linearly. The zoom lens thus achieves compact overall length while maintaining the necessary optical path length for multiple lens groups to perform magnification and focusing functions.
Solution Approach 2:
The patent arranges lens groups and the light path changing member in a nested or folded configuration where components are positioned to utilize space efficiently. The intermediate lens group is placed between the object-side and image-side lens groups, and the light path changing member is integrated into this arrangement, allowing the optical system to be compact while maintaining functional separation of lens groups.
2Reliability
If the number of lenses and lens groups is increased to achieve high magnification change and satisfactory aberration correction, then the imaging quality is improved, but the device complexity and space requirements increase
Solution Approach 1:
The patent designs each lens group to perform multiple functions. The object-side lens group with negative refractive power contributes to both wide-angle imaging and aberration correction. The intermediate lens group with positive refractive power assists in both magnification change and distortion correction. The image-side lens group with negative refractive power helps control both chromatic aberration and field curvature. This multi-functional design allows satisfactory aberration correction with a relatively small number of lens groups.
Solution Approach 2:
The patent specifies particular refractive power relationships between lens groups to optimize performance. The composite focal lengths of lens groups are constrained within specific ranges relative to the overall focal length of the zoom lens. These parameter constraints ensure that each lens group contributes effectively to aberration correction while maintaining compact dimensions and enabling high magnification change.
3Adaptability or versatility
If the zoom lens is designed for wide-angle views and high magnification change, then the versatility and imaging quality are improved, but the thickness and overall size of the lens increase
Solution Approach 1:
The patent uses a light path changing member to bend the optical path, transforming the linear arrangement into a folded configuration. This allows the zoom lens to achieve wide-angle views and high magnification change without increasing thickness, as the optical path length is accommodated in a bent rather than extended manner.
Solution Approach 2:
The patent employs a zoom lens mechanism where lens groups move dynamically along the optical axis to achieve magnification change from wide-angle to telephoto. The object-side and image-side lens groups move in opposite directions, while the intermediate lens group moves to assist in focusing and aberration correction. This dynamic arrangement allows the lens to maintain compact thickness while providing versatile imaging capabilities across different focal lengths.
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 allows for satisfactory aberration correction, including chromatic aberration and distortion, while achieving miniaturization and high image quality, with reduced thickness and improved portability in small devices.
Implementation Method 1
a light path changing member that is provided closer to the image plane side relative to those lenses and changes a traveling direction of an incident light
Implementation Method 2
The first lens group is composed of a lens having positive refractive power so that a curvature radius of a surface thereof on the object side is positive, a lens having negative refractive power so that a curvature radius of a surface thereof on the image plane side is positive
Data Source
AI summary
A zoom lens includes a first lens group, a second lens group, a third lens group, and a fourth lens group. The first lens group includes a first lens that has positive refractive power, a second lens that has negative refractive power, and a prism. The second lens group includes a third lens that has positive refractive power and a fourth lens that has negative refractive power. The third lens group includes a stop, a fifth lens that has positive refractive power, and a sixth lens that has negative refractive power. The fourth lens group includes a seventh lens that has positive refractive power. Upon changing magnification from a wide-angle end to a telephoto end, the first and fourth lens groups are fixed, the second lens group first moves toward an image plane side and then moves toward an object side, and the third lens group linearly moves toward the object side.