Four-Element Optical Lens Assembly with Aspheric Surfaces
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Solution Overview
Problem
Conventional compact imaging lens assemblies for portable electronic devices, comprising three or four lens elements, face challenges in reducing size, improving image quality, and correcting aberrations due to limited design flexibility and manufacturing complexities.
Innovation Solution
An optical image-capturing lens assembly with four lens elements, including a first lens with positive refractive power, a second with negative refractive power, a third with aspheric surfaces, and a fourth with a concave image-side surface and inflection points, optimized by specific geometric relationships and material choices (glass or plastic) to reduce total track length, enhance resolution, and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional three-lens element assembly is used, then the device is compact, but the image quality and resolution are insufficient for higher-end applications
Solution Approach 1:
The lens assembly is divided into four distinct lens elements with specific refractive power configurations (positive, negative, positive, positive), allowing each element to contribute differently to aberration correction and image quality enhancement, thereby resolving the contradiction between compactness and image quality
Solution Approach 2:
The second lens element is designed with a negative refractive power and specific surface curvatures to locally correct chromatic and spherical aberrations, while the fourth lens element has a concave image-side surface to specifically address field curvature, enabling targeted quality improvements without increasing overall complexity
2Manufacturing precision
If glass spherical surface lenses are used to form a doublet, then chromatic aberrations are corrected, but the total track length cannot be reduced and manufacturing becomes complicated
Solution Approach 1:
The patent employs aspheric surfaces instead of spherical surfaces for the second, third, and fourth lens elements, fundamentally changing the geometric parameter to achieve superior aberration correction. This allows for more effective control of light rays with fewer elements, thereby reducing the total track length while maintaining or improving correction quality
Solution Approach 2:
The lens assembly uses a combination of materials with different refractive indices and Abbe numbers across the four elements, creating a composite optical system that achieves chromatic aberration correction through material diversity rather than requiring complex glass doublet structures, thus shortening the overall length
3Manufacturing precision
If more lens elements are added to improve image quality, then resolution increases, but the device size and manufacturing complexity increase
Solution Approach 1:
The patent introduces inflection points on the aspheric surfaces of the second and fourth lens elements, creating dynamic surface profiles that can adaptively correct multiple types of aberrations simultaneously. This dynamic geometric design allows four elements to perform the work that would traditionally require more elements, reducing assembly complexity while maintaining high resolution
Solution Approach 2:
By changing from spherical to aspheric surfaces with inflection points, the patent fundamentally alters the surface geometry parameters, enabling each lens element to contribute more effectively to image quality. This parameter change allows the four-element assembly to achieve high resolution without the complexity of additional elements
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 reduces the size of the lens assembly, enlarges the field of view, and achieves higher resolution while simplifying manufacturing and improving image quality by distributing refractive power and correcting aberrations.
Implementation Method 1
a first lens element with positive refractive power; a second lens element with negative refractive power
Data Source
AI summary
This invention provides an optical image-capturing lens assembly comprising, in order from an object side to an image side: a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element, the object-side and image-side surfaces thereof being aspheric; and a fourth lens element having a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on at least one of the object-side and image-side surfaces thereof. The present lens assembly is further provided with a stop and an electronic sensor for image formation of an object. The stop is disposed between the object and the second lens element, and the electronic sensor is disposed at an image plane.