Front-Focus Imaging Lens with Integral Moving Groups
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Solution Overview
Problem
Existing imaging lenses face challenges in miniaturization and optical performance, with complex mechanisms and increased size due to floating systems, which fail to adequately address the demand for smaller size and higher image sensor ratios, especially when focusing from infinity to close-range objects.
Innovation Solution
A front-focus-type imaging lens configuration comprising a first lens group with positive refractive power, a diaphragm, and a second lens group with positive refractive power, where the first and second lens groups move integrally during focusing, while the third lens group remains stationary, satisfying specific conditional expressions for curvature and focal lengths to achieve a compact size and simplified mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floating system is employed to improve optical performance during focusing, then aberration correction is enhanced, but the mechanism becomes complicated and the lens barrel size increases
Solution Approach 1:
The lens system is divided into three distinct lens groups (G1, G2, G3) with different functions. The first lens group G1 includes multiple lenses for aberration correction, the second lens group G2 handles focusing movement, and the third lens group G3 remains stationary for stable image formation. This segmentation allows each group to be optimized independently, simplifying the overall mechanism while maintaining optical performance.
Solution Approach 2:
Instead of using a floating system where multiple lens groups move relative to each other during focusing, this invention inverts the approach by keeping the third lens group G3 stationary and moving only the second lens group G2. This reverse approach simplifies the focusing mechanism while the first lens group G1 is designed with specific curvature relationships to correct aberrations without requiring complex floating movements.
2Length of moving object
If the lens system is miniaturized to reduce size, then the total length decreases, but the optical performance and image quality deteriorate
Solution Approach 1:
The lens groups are arranged in a compact nested configuration where the first lens group G1 with positive power is positioned closest to the object, followed by the second lens group G2 with negative power, and the third lens group G3 with positive power nearest to the image plane. This nested arrangement optimizes space utilization and allows the lens system to achieve miniaturization while maintaining effective optical paths for high-quality image formation.
Solution Approach 2:
The invention employs specific parameter relationships, particularly the curvature radius ratio R1Yr/R1Zf between 1.01 and 1.7 for the first lens group, and controlled focal length ratios between lens groups. These parameter optimizations enable the compact lens design to achieve both miniaturization and high optical performance by precisely tuning the optical characteristics within the constrained space.
3Reliability
If more lenses are added to improve aberration correction, then optical performance improves, but the lens diameter and total length increase
Solution Approach 1:
The first lens group G1 is specifically designed with local quality optimization, where the curvature radius of the image-side surface of the second lens (R1Yr) and the object-side surface of the lens closest to the image side (R1Zf) maintain a specific ratio. This localized curvature optimization enables effective aberration correction within the first lens group without requiring additional lenses that would increase the overall lens diameter.
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 results in a smaller, more compact imaging lens with improved optical performance, simplifying the apparatus configuration and reducing manufacturing costs by minimizing lens diameter and total length, while effectively correcting various aberrations and maintaining image quality across focus ranges.
Implementation Method 1
During focusing from an infinite distance object to a close-range object, the first lens group, the diaphragm, and the second lens group integrally moves to the object side
Implementation Method 2
a first lens group that has a positive refractive power; a diaphragm; a second lens group that has a positive refractive power; and a third lens group
Data Source
AI summary
The imaging lens consists of, in order from the object side, a first lens group G1 having a positive power, a diaphragm, a second lens group G2 having a positive power, and a third lens group G3. Each of the lens groups includes three or more lenses. A positive lens is disposed on a most object side in the first lens group G1, and a meniscus lens, which is concave toward the object side, is disposed to be closest to the object side in the second lens group G2. During focusing from an infinite distance object to a close-range object, elements ranging from the first lens group G1 to the second lens group G2 integrally move toward the object side, and the third lens group G3 remains stationary. The imaging lens satisfies a conditional expression about a radius of curvature of an air lens of the first lens group G1.