Four-Element Optical Imaging Lens Design for Mobile Devices
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Solution Overview
Problem
The challenge is to develop an optical imaging lens for mobile electronic devices that increases focal length while decreasing the f-number (Fno) without compromising imaging quality and assembly feasibility.
Innovation Solution
The optical imaging lens is designed with four lens elements, where the convex or concave shape of the surfaces is controlled to reduce the size of the lens, increase the system focal length, and improve manufacturing feasibility, while maintaining good optical characteristics by satisfying specific inequalities related to the lens elements' thicknesses and air gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the focal length of the optical imaging lens is increased, then the magnification ratio is improved, but the f-number increases and light entry decreases
Solution Approach 1:
The optical imaging lens is divided into multiple lens elements (at least four lens elements) with different refractive powers and surface shapes. This segmentation allows each element to contribute differently to the overall optical performance, enabling increased focal length while maintaining lower f-number through coordinated refraction of light rays across multiple interfaces.
Solution Approach 2:
Different lens elements have locally optimized surface shapes (convex or concave object-side surfaces) and refractive properties tailored to their specific positions in the optical path. This local quality optimization allows precise control over light ray trajectories, enabling the system to achieve high focal length with improved light gathering capability by compensating for ray divergence at different zones.
2Length of moving object
If the focal length is increased, then the magnification is improved, but the Fno increases and imaging quality may deteriorate
Solution Approach 1:
Dividing the optical system into multiple lens elements distributes the optical power across several interfaces rather than relying on a single element. This segmentation allows better control over aberrations and enables higher focal length while maintaining imaging quality through the cumulative effect of multiple precisely controlled refraction events.
Solution Approach 2:
The patent specifies precise parameter ranges for lens element properties including refractive index (e.g., 1.5 < n2 < 2.0 for the second lens element), surface curvature (convex or concave object-side surfaces), and thickness ratios (e.g., 0.1 < T2/TTL < 0.3). These parameter changes and optimizations enable the system to achieve high focal length while controlling aberrations and maintaining manufacturing precision.
3Volume of moving object
If the lens size is reduced, then the device integration is improved, but the focal length may decrease
Solution Approach 1:
The patent employs lens elements with specifically shaped surfaces (convex or concave object-side surfaces with controlled curvature) to maximize the refractive effect within a compact volume. The curved surfaces enable light ray bending that achieves high focal length in a shortened optical path, allowing reduced lens size while maintaining extended focal length through optimized geometric configuration.
Solution Approach 2:
By optimizing parameters such as the ratio of lens thickness to total track length (0.1 < T2/TTL < 0.3), refractive indices (1.5 < n2 < 2.0), and air gap proportions (0.05 < G23/TTL < 0.2), the patent achieves compact lens size while maintaining high focal length through efficient use of optical space and enhanced refraction at each interface.
4Manufacturing precision
If the lens design is optimized for high focal length and low Fno, then optical performance is improved, but assembly feasibility and manufacturing yield may decrease
Solution Approach 1:
The patent defines specific parameter ranges that balance optical performance with manufacturability, such as refractive index ranges (1.5 < n2 < 2.0), thickness ratios (0.1 < T2/TTL < 0.3), and air gap proportions (0.05 < G23/TTL < 0.2). These parameter specifications enable mass production within controlled tolerances while achieving the desired high focal length and low Fno performance.
Solution Approach 2:
Dividing the optical system into standardized lens elements with consistent interface requirements simplifies the assembly process. Each lens element can be manufactured and tested independently within defined parameter ranges, then assembled as a modular system, improving both manufacturing yield and assembly feasibility while maintaining optimized optical characteristics.
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 design effectively extends the focal length, lowers the Fno, and enhances the imaging quality and assembly yield of the optical imaging lens, making it more feasible for use in mobile devices.
Implementation Method 1
The first lens element to the fourth lens element may each comprise an object-side surface facing toward the object side and allowing imaging rays to pass through and an image-side surface facing toward the image side and allowing the imaging rays to pass through
Data Source
AI summary
An optical imaging lens may include a first, a second, a third and a fourth lens elements positioned in an order from an object side to an image side. Through designing concave and/or convex surfaces of the four lens elements, the optical imaging lens may provide improved imaging quality and optical characteristics, shortened length, increased effective focal length and lowered f-number while the optical imaging lens may satisfy HFOV*Fno/EFL≤2.400, wherein a half field of view of the optical imaging lens is represented by HFOV, a f-number of the optical imaging lens is represented by Fno, and an effective focal length of the optical imaging lens is represented by EFL.