Polarizing Plastic Lens Wrinkle Prevention via Resin Flow Alignment

Solution Overview

Problem

The existing methods for manufacturing polarizing plastic lenses using injection molding face challenges in forming aspherical surfaces, as the bending of polarizing sheets often results in wrinkles due to inaccuracies in bending directions, leading to defects on the lens surface.

Innovation Solution

The method involves aligning the polarizing sheet's high-accuracy bending direction as a reference axis and loading it into the mold such that the filling direction of resin is not orthogonal to this axis, ensuring the polarizing axis is not parallel to the center gate direction, thereby preventing wrinkles by precise resin filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If bending is performed to the polarizing sheet to have a curved surface approximate to a molding surface, then the polarizing sheet can be deformed to agree with the molding surface due to heat and filling pressure, but wrinkles easily occur on the lens surface when the curve is deeper than the molding surface

Engineering Contradiction:

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The polarizing sheet is pre-bent to match the curvature of the molding surface before injection molding. This preliminary shaping ensures that the sheet conforms to the desired lens curvature, reducing the magnitude of deformation required during molding and preventing wrinkles caused by excessive bending.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent controls the bending parameters of the polarizing sheet, specifically ensuring that the curve depth does not exceed the molding surface curvature. By adjusting the bending radius and curvature to match or be shallower than the mold, the sheet can be properly deformed during injection without forming wrinkles.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the polarizing sheet is loaded with center side contact to the molding surface, then the sheet is prevented from extending while adhering from center toward outer circumferential side, but wrinkles occur in the portion that does not extend anymore

Engineering Contradiction:

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The polarizing sheet is pre-shaped with a curvature that matches the molding surface before injection. This preliminary curvature adjustment ensures proper contact and extension behavior during molding, preventing wrinkles in portions that would otherwise fail to extend properly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of allowing the sheet to extend from the center outward during molding (which causes wrinkles when contact is made), the patent inverts the approach by pre-bending the sheet to match the final curvature. This reverses the deformation sequence, eliminating the extension problem that causes wrinkles.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If bending is performed in direction orthogonal to polarizing axis, then the curve bends to be shallow on center side and deep on outer circumferential side, but this directional inaccuracy causes wrinkles

Engineering Contradiction:

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the bending parameters by performing the bending operation in the direction parallel to the polarizing axis rather than orthogonal to it. This parameter change in bending direction ensures uniform and accurate curvature formation, eliminating the directional inaccuracy that causes wrinkles.

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 approach effectively inhibits the occurrence of wrinkles on the lens surface, resulting in high-quality polarizing plastic lenses with improved optical surface accuracy.

Implementation Method 1

deforming the polarizing sheet to be integrally molded with a lens body, also can manufacture the polarizing plastic lens having a desired optical surface shape

Methodology Applied

Scientific EffectHeat: Heating

Implementation Method 2

injection molding process with thermoplastic resin

Methodology Applied

Scientific EffectInjection molding:

Data Source

PatentUS10525645B2Method for manufacturing functional plastic lens and polarizing plastic lens

Publication Date: 2020.01.07

AI summary

In manufacturing a functional plastic lens by loading a functional sheet S having a difference in the accuracy of bending in directions, into a mold 50 and by performing insert molding to integrally mold a lens body with the functional sheet S, a direction in which the accuracy of the bending to the functional sheet S is high is made to be a reference axis A, and the functional sheet S is loaded into the mold 50 to inhibit a filling direction of resin and the reference axis A from being orthogonal to each other. With this arrangement, the functional plastic lens having high quality is provided.