Compact Zoom Lens System With Folded Optical Path
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Solution Overview
Problem
Conventional zoom lens systems for compact image pickup devices are limited by size, cost, and durability due to the need for multiple movable lens groups and light path bending elements, which increase the overall length and weight, while compromising on dust and water protection.
Innovation Solution
A compact zoom lens system with three lens groups, where the first group is stationary with a reflecting element for path bending, and the second and third groups are movable, featuring aspheric surfaces to correct aberrations and maintain a fixed overall length, comprising six lenses and a right-angle prism for optical path manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple movable lens groups and light path bending elements are used to achieve zoom functionality, then the zoom ratio and imaging performance are improved, but the overall length and weight of the lens system increase
Solution Approach 1:
The patent introduces a light path bending element (prism or mirror) to change the optical path from a linear arrangement to a folded geometry. This allows the lens groups to be arranged in a compact configuration where light reflects at angles, effectively shortening the overall length of the lens system while maintaining the zoom functionality through the movement of lens groups along the optical axis.
Solution Approach 2:
The lens system is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, third lens group with positive refractive power) that can move independently along the optical axis. This segmentation allows each group to be optimized for specific functions (zooming, focusing) while maintaining a compact overall structure when not in use.
2Manufacturing precision
If multiple movable lens groups are used to achieve zooming and focusing, then the imaging performance is improved, but the durability and dust/water protection are compromised
Solution Approach 1:
Instead of making the lens barrel extend outward to accommodate movable lens groups (which compromises dust and water protection), the patent inverts the approach by having the lens groups move inward along a fixed optical axis. The first lens group remains stationary while the second and third lens groups move along the optical axis, maintaining a fixed overall length that preserves durability and protection while still enabling zoom and focus functions.
3Length of moving object
If a right-angle prism is added to bend the optical path, then the overall length is shortened, but the device complexity and cost increase
Solution Approach 1:
The light path bending element (prism or mirror) serves multiple functions: it bends the optical path to shorten the overall length, and can also serve as a structural support for mounting lens groups and as a protective cover for internal components. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite adding the optical path bending capability.
4Manufacturing precision
If five lens groups with 9 to 11 lens elements are used, then the imaging performance is improved, but the size, cost and weight of the image pickup device increase
Solution Approach 1:
The patent optimizes the refractive power parameters of each lens group to achieve the required imaging performance with fewer elements. The first lens group has positive refractive power, the second has negative refractive power, and the third has positive refractive power. By carefully selecting and optimizing these refractive power parameters, the system achieves good imaging quality with only three lens groups instead of five, thereby reducing the total number of lens elements, weight, and cost.
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 achieves a compact, reliable, and cost-effective zoom lens system with improved image quality by reducing the optical system length, correcting aberrations, and maintaining a fixed overall length, suitable for small-sized image pickup devices.
Implementation Method 1
a first lens group which is stationary and includes a reflecting element for bending an optical path
Implementation Method 2
each of the first, second and third lens groups has at least one aspheric lens surface
Data Source
AI summary
A compact zoom lens system includes, in order from an object side to an image side along an optical axis thereof, a first lens group having positive refractive power, a second lens group having positive refractive power and a third lens group also having positive refractive power. The first lens group is stationary and includes a reflecting element for bending the optical path. The second and third lens groups are movable along the optical axis, and each of the first, second and third lens groups has at least one aspheric lens surface. When zooming from a wide-angle end to a telephoto end, the second lens group moves toward the object side and the third lens group moves toward the image side, so as to reduce the spacing between the first and second lens groups and increase the spacing between the second and third lens groups. By this specific optical configuration, the compact zoom lens system has the advantages of small size, simple structure, low cost, good reliability and better image quality.