Compact Zoom Lens Design for Brightness and Miniaturization
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Solution Overview
Problem
Existing zoom lenses with a wide-angle end F number greater than 2.552 suffer from insufficient brightness and prolonged total optical length, limiting their miniaturization and optical performance, especially when the zoom ratio is greater than 4.74.
Innovation Solution
A zoom lens design comprising four lens groups with six lenses, where the on-axis distances and focal lengths are optimized to achieve a zoom ratio greater than 1.80, ensuring the lens becomes bright and compact, with a total optical length less than 8.00 mm, by adjusting the refractive powers and spacings of the lenses, particularly through relationships (1) to (9) that define the ratios and focal lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the F number of the wide-angle end is greater than 2.552, then the lens structure can be simplified, but the brightness becomes insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the F number of the wide-angle end to be 2.552 or less, and setting specific numerical ranges for focal lengths (f_Wide, f_Tele), on-axis distances (D12_Wide, D12_Tele, d11_Wide, d11_Tele), and spacing ratios. These parameter optimizations enable the lens to achieve high brightness while maintaining a compact structure with only six lenses arranged in four groups.
2Length of moving object
If the total optical length is reduced for miniaturization, then the lens can be accommodated in compact cameras, but the optical performance may deteriorate
Solution Approach 1:
The patent achieves miniaturization with excellent optical performance through parameter changes by setting the total optical length to 8.00 mm or less while establishing specific numerical relationships for focal lengths, on-axis distances, and spacing ratios. The four lens groups with six lenses are positioned according to precise parameter specifications that maintain optical quality despite the compact size.
Solution Approach 2:
The patent employs dynamics by making the spacing between adjacent lenses or lens groups variable during zooming. The on-axis distances D12 and d11 are designed to change dynamically between wide-angle and telephoto ends, with specific ratio constraints (40.00 ≤ D12_Wide/D12_Tele ≤ 48.00 and 2.00 ≤ d11_Wide/d11_Tele ≤ 2.60) that enable smooth zoom operation while maintaining compact dimensions.
3Adaptability or versatility
If the zoom ratio is increased to provide wider viewing range, then the lens coverage is improved, but the total optical length increases
Solution Approach 1:
The patent resolves the contradiction between zoom ratio and optical length through parameter changes by setting the zoom ratio to 1.80 or more while constraining the total optical length to 8.00 mm or less. This is achieved by optimizing the focal length ratio (f_Tele/f_Wide ≥ 1.80) and precisely controlling the on-axis distances and spacing ratios between lens groups, enabling high adaptability within a compact form factor.
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 zoom lens achieves good optical performance and miniaturization by ensuring the lens is bright and compact, with a zoom ratio greater than 1.80 and a total optical length less than 8.00 mm, addressing the issues of insufficient brightness and length in previous designs.
Implementation Method 1
a first lens L1 having a negative refractive power
Implementation Method 2
a second lens group G2 having a positive refractive power
Implementation Method 3
a fifth lens L5 having a positive refractive power
Implementation Method 4
a sixth lens L6 having a negative refractive power
Data Source
AI summary
The present disclosure relates to a technical field of optical lenses, and discloses a zoom lens. The zoom lens, being sequentially from an object side to an image side, includes a first lens having a negative refractive power, a second lens group having a positive refractive power, a fifth lens having a positive refractive power, and a sixth lens having a negative refractive power, when zooming, among the first lens, the second lens group, the fifth lens, and the sixth lens, a spacing in an optical axis direction of adjacent lenses or lens groups changes, the second lens group includes a second lens having a positive refractive power, a third lens having a negative refractive power, and a fourth lens having a negative positive power. During photographing, when an F number (FNO) of a wide-angle end is less than or equal to 2.0, the zoom lens becomes bright.