Compact Four-Lens Imaging System with Nested Shutter
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Solution Overview
Problem
Existing imaging lenses for digital and cellular phones face challenges in achieving a balance between compactness and high performance, particularly in securing sufficient space for a shutter mechanism while maintaining downsized and cost-effective manufacturing, and in reducing aberrations and chromatic aberration.
Innovation Solution
A four-lens configuration with specific power arrangements and shapes, including a meniscus-shaped fourth lens and aspherical surfaces, optimized to satisfy conditional expressions that ensure sufficient space for a shutter mechanism, reduce lens size, and enhance image forming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the aperture diaphragm and shutter mechanism are disposed nearer to the object side than the first lens to reduce shading and improve telecentric performance, then the image quality is improved, but the overall length of the lens increases which is disadvantageous for downsizing
Solution Approach 1:
The aperture diaphragm and shutter mechanism are nested within the lens system between the first and second lenses, utilizing the internal space of the lens structure. This allows the components to be housed without increasing the overall lens length, while still maintaining their functional requirements for reducing shading and improving telecentric performance.
Solution Approach 2:
Instead of positioning components along the optical axis in front of the lens (one-dimensional extension), the solution moves them into the internal volume of the lens system (three-dimensional utilization). This dimensional transition allows compact integration without extending the front focal distance.
2Length of moving object
If the aperture diaphragm and shutter mechanism are interposed between the first and second lenses to reduce overall length, then the lens is downsized, but sufficient space for arranging these components cannot be secured
Solution Approach 1:
The lens design optimizes specific local regions between the first and second lenses to provide adequate clearance for the aperture diaphragm and shutter mechanism. By carefully controlling the air gaps and component positions in these local areas, sufficient space is created for the mechanisms while maintaining the overall compact lens structure.
Solution Approach 2:
The air interval D2 between the first and second lenses is specifically optimized to provide the necessary space for the aperture diaphragm and shutter mechanism. By adjusting this parameter within a specific range (0.5mm ≤ D2 ≤ 2.0mm), the design secures adequate room for the components while maintaining compact overall dimensions.
3Manufacturing precision
If aspherical surfaces are used in the lenses to enhance performance and enable downsizing, then the image forming performance is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of making all lens surfaces aspherical, the invention applies aspherical surfaces only to specific lenses (the first, third, and fourth lenses) where they provide the most benefit for aberration correction and compactness. This partial application achieves the performance goals while reducing manufacturing complexity and cost compared to making all surfaces aspherical.
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 enables a compact, high-performance imaging lens that secures sufficient space for a shutter mechanism, reduces lens size, and corrects aberrations, making it suitable for both digital and cellular phone cameras with improved cost-effectiveness and image quality.
Implementation Method 1
a first lens (G1) having a convex surface on the object side and having a positive power
Implementation Method 2
a second lens (G2) having a concave surface on the object side and having a negative power
Implementation Method 3
a third lens (G3) having a positive power
Implementation Method 4
a fourth lens (G4) having a convex surface on the object side and near an optical axis of the imaging lens, the fourth lens having a meniscus shape
Data Source
Figure 1~2
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Figure 5~6
AI summary
A compact imaging lens e.g., for a cellular phone includes: in order from its object side, a first lens (G1) having a convex surface (R1) on the object side and having a positive power; an aperture diaphragm (St); a second lens (G2) having a concave surface (13) on the object side and having a negative power; a third lens (G3) having a positive power; and a fourth lens (G4) having a convex paraxial surface (R7) on the object side, the fourth lens having a meniscus shape. The imaging lens satisfies the two following inequalities: where f denotes the focal length of the imaging lens; D2 represents the air interval between the first lens and second lens along the optical axis; and TL represents the distance along the optical axis from the object-side surface of the first lens (G1) to the image plane (Simg).