Two-Element Plastic Lens Assembly Aberration Correction
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Solution Overview
Problem
Conventional photographing lens assemblies for portable electronic devices face challenges in minimizing size while maintaining low manufacturing costs and high image quality, often resulting in peripheral defocus and inadequate aberration correction due to the use of multiple lens elements.
Innovation Solution
A compact photographing lens assembly comprising a first lens element with positive refractive power and a second lens element with negative refractive power, both made of plastic or glass, where the second lens element's surface is aspheric and convex at the paraxial region and concave at the peripheral region, optimizing thickness and Abbe number ratios to correct aberrations and reduce the total track length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If at least three lens elements with refractive power are adopted, then the imaging capability is improved, but the size, manufacturing cost, and complexity of the lens assembly increase
Solution Approach 1:
The patent extracts and eliminates unnecessary lens elements by demonstrating that a two-element assembly (first lens element with positive refractive power and second lens element with negative refractive power) can achieve adequate imaging performance without requiring three or more lens elements. This reduction in element count directly lowers complexity while maintaining acceptable imaging capability.
Solution Approach 2:
The patent employs specific parameter relationships between the two lens elements, including the Abbe number relationship (V1²−V2²)/(V1−V2)² and thickness ratio (CT1/CT2), to optimize the optical performance. By carefully selecting and controlling these parameters, the patent achieves adequate aberration correction and imaging quality with fewer lens elements.
2Device complexity
If two lens elements are used to reduce size and cost, then the manufacturing cost and size are reduced, but peripheral defocus and aberration occur
Solution Approach 1:
The patent uses a composite lens assembly combining two different lens materials with complementary optical properties. The first lens element has positive refractive power and the second lens element has negative refractive power, creating a composite system that corrects aberrations and eliminates peripheral defocus while maintaining compact size.
Solution Approach 2:
The patent employs aspheric surfaces on the lens elements, particularly the second lens element which has an aspheric image-side surface. This curvature design enables the two-element assembly to achieve adequate aberration correction and eliminate peripheral defocus that would otherwise occur with simpler lens configurations.
3Ease of manufacture
If conventional lens materials are used, then manufacturing is simplified, but aberration correction and chromatic aberration are insufficient
Solution Approach 1:
The patent optimizes the Abbe numbers and thickness ratios of the lens elements to achieve adequate aberration correction. The specific relationship V1²−V2²/(V1−V2)² and the thickness ratio CT1/CT2 are controlled within defined ranges to balance manufacturing feasibility with optical performance, enabling adequate correction of aberrations and chromatic aberration.
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 achieves a compact size, low manufacturing costs, and high image quality by effectively correcting aberrations and reducing peripheral defocus, while allowing for flexible design of refractive power distribution and reduced lens element count.
Implementation Method 1
a first lens element with positive refractive power has an object-side surface and an image-side surface
Implementation Method 2
a second lens element with negative refractive power is made of plastic material, and has an object-side surface and an image-side surface
Data Source
AI summary
A photographing lens assembly includes, in order from an object side to an image side, a first lens element and a second lens element. The first lens element with positive refractive power has an object-side surface and an image-side surface, wherein the object-side surface and the image-side surface of the first lens element are convex at a paraxial region thereof. The second lens element with refractive power is made of plastic material, and has an object-side surface and an image-side surface, wherein the object-side surface of the second lens element is convex at a paraxial region thereof, the image-side surface of the second lens element is concave at the paraxial region and is convex at a peripheral region thereof, and the object-side surface and the image-side surface of the second lens element are aspheric.