Plastic Optical Lens Thickness Reducing Region
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Solution Overview
Problem
The uneven thickness of plastic optical lenses during the injection molding process leads to unsatisfactory molding results and affects image quality due to differences in cooling rates and filling imbalances, particularly in lenses with thin central regions and thicker connecting portions.
Innovation Solution
A plastic optical lens design with a thickness reducing region between the optical effective and peripheral portions, ensuring the connecting portion has a minimum thickness that minimizes thickness differences, allowing for uniform cooling and improved mold filling, thus preventing abnormal shrinkage and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the connecting portion has a simple shape with uniform thickness, then the molten plastic material can favorably fill the lens mold and achieve uniform shrinkage, but the thickness difference between the connecting portion and the central region of the optical effective portion becomes increased, causing unsatisfactory molding results
Solution Approach 1:
The connecting portion is designed with a thickness reducing region that creates a gradual thickness transition from the peripheral portion to the optical effective portion. This local variation in thickness allows the molten plastic material to flow uniformly throughout the mold cavity while maintaining appropriate wall thicknesses, thereby achieving both satisfactory mold filling and uniform shrinkage without excessive thickness differences.
2Volume of moving object
If the central region of the optical effective portion is made extremely thin to achieve compact size, then the lens becomes more compact, but the thickness difference between the connecting portion and the central region is increased, leading to abnormal shrinkage and warpage
Solution Approach 1:
The connecting portion incorporates a thickness reducing region that provides a gradual transition in thickness from the peripheral portion to the optical effective portion. This gradual reduction prevents abrupt thickness changes that would cause abnormal shrinkage and warpage, while still allowing the central region to maintain an extremely thin profile for compact lens size.
Solution Approach 2:
The thickness reducing region is pre-designed into the connecting portion structure before molding. This preliminary geometric configuration ensures that the molten plastic material experiences uniform cooling rates throughout the mold cavity, preventing abnormal shrinkage and warpage during the cooling process while maintaining the desired compact dimensions.
3Speed
If the molten plastic material flows through the region of the mold with greater depth at higher speed, then the filling process is faster, but filling imbalances occur and warpage is caused
Solution Approach 1:
The connecting portion is designed with a thickness reducing region that creates a gradual thickness transition. This local geometric variation ensures that the molten plastic material flows at controlled speeds throughout the mold cavity, preventing excessive flow speed in deep regions while maintaining efficient filling. The gradual thickness reduction balances the flow dynamics, achieving uniform filling without warpage.
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 design ensures satisfactory molding results and improved image quality by maintaining uniform cooling rates across the lens, reducing the likelihood of abnormal shrinkage and enhancing the precision of the injection molding process.
Implementation Method 1
the portion of the molten plastic material in a region of the mold with a greater depth likely shrinks during the cooling process because it takes longer to be cooled
Implementation Method 2
the stress of the solidified portion of the plastic article (in the region of the mold with a smaller depth) will increase and cause warpage
Data Source
AI summary
This invention provides an injection-molded plastic optical lens comprising from a center to an edge thereof an optical effective portion, a connecting portion and a peripheral portion that are concentrically formed. The plastic optical lens has an outer diameter D. The optical effective portion has an edge thickness ET1 and a central thickness CT, the connecting portion has a minimum thickness ET2, and the plastic optical lens satisfies the following relations of CT≦0.30 mm and ET2/ET1<1.0. At least one lens element with refractive power can be disposed at each of the object side and the image side of the plastic optical lens of the present invention to form an optical lens assembly.