Four-Lens Optical System for Mobile Camera Miniaturization
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Solution Overview
Problem
Conventional optical lens systems for mobile phone cameras, with three or four glass spherical lens elements, face challenges in achieving higher resolution and miniaturization due to insufficient degrees of freedom and increased manufacturing complexity, while also struggling to correct chromatic aberration and other optical aberrations effectively.
Innovation Solution
A four-lens optical lens system with a specific arrangement of refractive powers, including a strong positive first lens element, a negative second lens element for chromatic aberration correction, and alternating negative and positive third and fourth lens elements to balance aberrations, along with an aperture stop placement that enhances telecentricity and reduces the total track length, using either glass or plastic materials with aspheric surfaces to optimize image quality and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional three-lens element system is used, then the device complexity is low, but the image quality cannot satisfy higher resolution requirements
Solution Approach 1:
The optical system is segmented into four distinct lens elements with specific refractive power distributions. The first lens element provides strong positive refractive power, the second element corrects chromatic aberration with negative refractive power, and the third and fourth elements balance various aberrations through alternating negative and positive refractive powers. This segmentation allows each element to perform specialized functions, achieving high image quality while maintaining manageable system complexity.
2Manufacturing precision
If multiple glass spherical lens elements are used to correct aberrations, then image quality improves, but manufacturing difficulty increases
Solution Approach 1:
The patent specifies precise parameter ranges for each lens element, including refractive indices (e.g., 1.5-1.7 for positive lenses, 1.6-1.8 for negative lenses), curvatures, and thicknesses. By optimizing these parameters, the system achieves effective aberration correction while using standard glass materials and conventional manufacturing processes, thereby reducing manufacturing difficulty compared to using multiple complex glass spherical elements.
3Length of stationary object
If the total track length is reduced for miniaturization, then the device size decreases, but aberration correction becomes more difficult
Solution Approach 1:
The patent addresses the miniaturization challenge by optimizing the spatial arrangement of lens elements along the optical axis and by using aspheric surfaces with specific conic coefficients. The fourth lens element, in particular, employs an aspheric surface with a conic coefficient between -0.5 and -1.0 to correct off-axis aberrations. This dimensional optimization allows the system to maintain compact total track length while achieving effective aberration correction through sophisticated surface geometry.
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 effectively improves image quality, reduces the total track length, and maintains miniaturization by balancing refractive powers and correcting various aberrations, while allowing for cost-effective high-precision lens production using either glass or plastic materials, thus addressing the limitations of conventional systems.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with negative refractive power; a fourth lens element with positive refractive power having a concave image-side surface
Data Source
AI summary
An optical lens system for taking image has, in order from the object side to the image side: a positive first lens element with a convex object-side surface; a negative plastic second lens element with a concave object-side surface; a negative plastic third lens element with a concave object-side surface; a positive fourth lens element with a concave image-side surface; and an aperture stop located between an object to be photographed and the second lens element. The second lens element is provided with at least one aspheric surface, the third lens element is provided with at least one aspheric surface, and the fourth lens element is formed with inflection points. An on-axis distance between the first and second lens elements is T12, a focal length of the optical lens system for taking image is f, they satisfy the relation: (T12/f)*100>0.7.