Plastic Lens Element with Concave Strip Structures for Shrinkage Control

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Solution Overview

Problem

Conventional plastic lens elements for large aperture and high-resolution lens modules face issues with uneven shrinkage and warpage during molding, leading to poor optical quality and increased costs due to complex mold machining and unnecessary thickness.

Innovation Solution

Incorporating curve-shaped strip structures around the optical effective portion of the plastic lens element, which are curved in a concave form and not directly connected to the optical effective portion, to reduce shrinkage and maintain optical quality, while allowing for efficient injection molding and minimizing additional thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the plastic lens element is made thinner to satisfy large aperture and high resolution specifications, then the optical effective portion area is improved, but the lens element becomes more prone to uneven shrinkage and warpage during molding

Engineering Contradiction:

Improveoptical effective portion areaVSAvoidshrinkage uniformity

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The lens element is divided into multiple regions with different thicknesses, creating a non-uniform thickness distribution. This segmentation allows different parts of the lens to shrink at different rates during molding, compensating for the overall thinness and preventing uneven shrinkage and warpage while maintaining a large optical effective portion area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the lens element are designed with different local thickness characteristics. The lens includes a central region and peripheral regions with varying thickness profiles, allowing each region to undergo controlled shrinkage during molding. This local quality variation prevents warpage while preserving the large aperture area needed for high resolution.

Inventive Principle:

Principle #3Local quality

2Strength

If strip structures are added to the plastic lens element to improve structural integrity, then the lens strength is improved, but the lens element experiences uneven shrinkage along the shrinkage direction

Engineering Contradiction:

Improvelens structural strengthVSAvoidshrinkage uniformity

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The strip structures are designed with asymmetric thickness variations and curved configurations rather than uniform symmetric patterns. This asymmetric design allows the strips to provide structural reinforcement while their varying cross-sections and curved shapes enable them to accommodate differential shrinkage during molding, preventing the formation of fine lines and maintaining surface quality.

Inventive Principle:

Principle #4Asymmetry

3Area of stationary object

If the outer diameter of the plastic lens element is increased to provide larger optical effective portion, then the aperture ratio is improved, but the lens element is more susceptible to warpage during molding

Engineering Contradiction:

Improveoptical effective portion areaVSAvoidlens shape stability

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

Instead of uniformly increasing the outer diameter, the lens design incorporates dimensional variations in the thickness dimension. The non-uniform thickness distribution allows the lens to have a large optical effective portion area while the varying thickness provides internal structural support that stabilizes the lens shape during molding, preventing warpage.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Ease of manufacture

If conventional molding processes are used for thin lens elements, then the manufacturing simplicity is maintained, but the optical quality of the lens effective portion is degraded due to warpage

Engineering Contradiction:

Improvemolding process simplicityVSAvoidoptical surface quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The lens element is designed with pre-calculated non-uniform thickness distribution and strip structure configurations that are optimized to compensate for expected shrinkage behavior during molding. This preliminary design action ensures that when conventional molding processes are used, the lens achieves high optical quality without requiring complex molding modifications, as the design itself pre-compensates for warpage tendencies.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11635548B2Plastic lens element, plastic annular optical element, lens module and electronic device

Publication Date: 2023.04.25 LARGAN PRECISION

AI summary

A plastic lens element includes an optical effective portion and a lens peripheral portion in order from a central axis to an edge of the plastic lens element. The lens peripheral portion surrounds the optical effective portion and includes a plurality of curve-shaped strip structures. Each of the curve-shaped strip structures is located and extended along a radial direction of the central axis. Each of the curve-shaped strip structures is curved in a concave form. The curve-shaped strip structures are prearranged in a circumferential direction of the central axis and around the optical effective portion. The curve-shaped strip structures are not directly connected to the optical effective portion.