Five-Element Plastic Lens Assembly with Inflection Points

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Solution Overview

Problem

Conventional compact image capturing optical lens assemblies for mobile electronic products face challenges in achieving high image quality and compact size due to limitations in the four-element lens structure, which cannot satisfy increasing pixel and image-quality requirements.

Innovation Solution

The proposed image capturing optical lens assembly consists of five elements, including a first lens with positive refractive power, a second lens with negative refractive power, a third lens with aspheric surfaces, a fourth lens with positive refractive power, and a fifth lens made of plastic with a concave image-side surface and at least one inflection point, optimized to reduce total track length and correct aberrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional four-element lens structure is used, then the device complexity is reduced, but the imaging quality and ability to satisfy high pixel requirements deteriorates

Engineering Contradiction:

Improvelens structure complexityVSAvoidimaging quality

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent divides the optical system into five distinct lens elements instead of four, with each element having specific refractive power and surface characteristics. This segmentation allows for more precise correction of optical aberrations while maintaining compact dimensions, directly resolving the contradiction between simple structure and high imaging quality.

Inventive Principle:

Principle #1Segmentation

2Volume of moving object

If the lens assembly is miniaturized for mobile products, then the size is reduced, but the total track length becomes too short to achieve good imaging quality

Engineering Contradiction:

Improvelens assembly sizeVSAvoidimaging quality

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent employs aspheric surfaces on multiple lens elements (first, third, and fourth elements) with specifically designed curvature radii and conic coefficients. This parameter optimization allows the compact five-element assembly to achieve excellent imaging quality despite the constrained total track length in mobile devices.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces inflection points on the surfaces of lens elements, particularly the fifth element, to control off-axis light rays. This dimensional control of surface geometry enables effective aberration correction in the compact configuration, resolving the trade-off between small size and imaging quality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If more lens elements are added to improve imaging quality, then the imaging quality is enhanced, but the total track length increases

Engineering Contradiction:

Improveimaging qualityVSAvoidtotal track length

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The patent uses aspheric surfaces with optimized curvature radii and conic coefficients on the first, third, and fourth lens elements. This allows each element to contribute more effectively to aberration correction, achieving high imaging quality with only five elements and a compact total track length of 3.49mm.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent assigns different surface characteristics to different lens elements - the first element has aspheric surfaces, the third element has aspheric surfaces with specific convex object-side surfaces, and the fifth element has inflection points. This localized optimization of surface quality enables effective aberration control without increasing overall length.

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If plastic material is used for the fifth lens element, then the manufacturing cost is reduced, but the precision and quality control becomes more challenging

Engineering Contradiction:

Improvemanufacturing costVSAvoidquality control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent specifies precise aspheric surface parameters for the plastic fifth lens element, including curvature radii and conic coefficients with inflection points. These carefully controlled parameters enable mass production of plastic lenses with consistent high quality, resolving the contradiction between manufacturing ease and quality control.

Inventive Principle:

Principle #35Parameter changes

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 configuration enhances imaging quality, reduces the total track length, and maintains a compact size by effectively correcting aberrations and minimizing the incident angle of off-axis fields on the image sensor, while allowing for the use of plastic materials to lower manufacturing costs.