Five-Element Image Lens Assembly with Aspheric Surfaces
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Solution Overview
Problem
Conventional compact image lens assemblies for portable electronic devices fail to meet the increasing demands for higher image quality and smaller size, particularly in mobile products with high pixel and image-quality requirements.
Innovation Solution
A compact image lens assembly comprising five lens elements with specific refractive powers and aspheric surfaces, including a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power and aspheric surfaces, a fourth lens made of plastic with positive refractive power and aspheric surfaces, and a fifth lens with negative refractive power, optimized to minimize total track length and correct aberrations, while maintaining image quality and compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional four-element lens structure is used, then the device complexity is low, but the image quality and miniaturization requirements cannot be satisfied
Solution Approach 1:
The lens assembly is divided into five distinct lens elements with different refractive powers and material properties. Each element is optimized for specific functions: the first element (positive refractive power, glass) provides initial light gathering, the second element (negative refractive power, plastic) corrects aberrations, the third element (positive refractive power, aspheric surface) controls spherical aberration, the fourth element (positive refractive power, plastic, aspheric surface) manages chromatic aberration, and the fifth element (negative refractive power, plastic, aspheric surface) finalizes the optical path. This segmentation allows each element to be optimized independently while working together to achieve high image quality in a compact form factor.
Solution Approach 2:
The lens assembly employs a composite material strategy by combining glass and plastic materials across different lens elements. Specifically, the first lens element uses glass material for its high refractive index and excellent optical transmission, while the second, fourth, and fifth lens elements use plastic materials for weight reduction and compactness. The third lens element uses plastic with aspheric surfaces to control aberrations. This composite approach balances optical performance requirements with miniaturization and weight constraints.
2Volume of moving object
If the total track length is reduced for compact size, then the miniaturization requirement is met, but the image quality and aberration correction become more difficult to maintain
Solution Approach 1:
Multiple lens elements in the assembly feature aspheric surfaces (third, fourth, and fifth lens elements) that are specifically designed to correct spherical aberration and other optical defects. The aspheric curvature parameters are optimized to work within a compact total track length while maintaining excellent image quality across the sensor array. This spheroidality principle allows the lens to achieve high precision optical performance without requiring excessive length.
Solution Approach 2:
The lens design employs precise parameter optimization including refractive indices, curvatures, thicknesses, and spacing between elements. By carefully adjusting these parameters, the assembly achieves a compact total track length while maintaining high image quality. The aspheric coefficients and material selection are specifically tuned to correct aberrations within the constrained space, demonstrating how parameter changes enable simultaneous miniaturization and high performance.
3Manufacturing precision
If higher pixel density is implemented, then the image quality requirement increases, but the lens assembly size and complexity must be reduced
Solution Approach 1:
Each lens element is designed with local optical quality optimized for its specific position and function within the compact assembly. The aspheric surfaces are strategically placed at positions where they provide maximum aberration correction for the high-density pixel sensor. The material selection and curvature parameters are locally optimized to match the specific optical requirements at each stage of light transmission, enabling high image quality across the entire sensor array 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 solution provides improved image quality, reduced total track length, and compact size, while maintaining favorable light entry and balancing telecentric and wide-angle characteristics, effectively addressing the limitations of conventional four-piece lens structures.
Implementation Method 1
a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with refractive power
Data Source
AI summary
An image lens assembly includes, in order from an object side to an image side, the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power, the third lens element with refractive power, the fourth lens element with positive refractive power made of plastic material, the fifth lens element with negative refractive power made of plastic material. At least one surface of the third lens element, the fourth lens element and the fifth lens element are aspheric.