Plastic Lens Peripheral Strip Ribs for Non-Imaging Light Attenuation
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Solution Overview
Problem
Conventional compact photographing lens modules with plastic lens elements face challenges in reducing non-imaging light reflection, which affects image quality, especially due to the limitations of applying ink coatings on small, high-accuracy plastic lens elements and the difficulty in configuring optical refractive index matching layers.
Innovation Solution
The design incorporates a plastic lens element with an aspheric effective optical portion and a peripheral portion featuring strip rib structures and light-absorbing coatings, arranged in a radial direction to effectively attenuate non-imaging light, using a needle-coating method to control the coating range and prevent reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ink coating method is used on plastic lens elements, then non-imaging light reflection can be suppressed, but manufacturing precision deteriorates due to ink application variation exceeding the scale of compact plastic lens elements
Solution Approach 1:
The peripheral portion of the lens element is segmented into multiple strip rib structures arranged in radial directions, creating distinct zones for light absorption. This segmentation allows precise control of ink coating areas while maintaining manufacturing feasibility, as each strip can be independently formed during injection molding.
Solution Approach 2:
The strip rib structures are pre-formed on the lens element surface during the injection molding process, before the ink coating step. This preliminary structuring provides defined boundaries and surfaces for subsequent ink application, significantly improving coating precision compared to applying ink directly on smooth surfaces.
2Object-affected harmful factors
If optical refractive index matching layer is configured in gap between black barrel and lens element, then reflection at lens element edge can be reduced, but device complexity increases due to limitations in configuring the matching layer
Solution Approach 1:
The light-absorbing peripheral portion is merged with the lens element body as an integrated structure formed during injection molding, eliminating the need for separate matching layers or additional assembly steps. The strip rib structures and light-absorbing material become part of the lens element itself, simplifying the overall device configuration.
Solution Approach 2:
The lens element structure itself provides the light-absorbing function through its integrated peripheral portion with strip rib structures, eliminating the need for external matching layers or additional components. The structure serves both its optical function and the light absorption function simultaneously.
3Ease of manufacture
If conventional plastic lens element with smooth surface is used, then manufacturing cost is reduced, but image quality deteriorates due to high reflectivity of the smooth surface
Solution Approach 1:
The lens element exhibits different surface qualities in different regions: the effective optical portion maintains a smooth surface for optimal light transmission and imaging, while the peripheral portion features strip rib structures with light-absorbing material for reflection suppression. This local differentiation achieves both cost-effectiveness and improved image quality.
Solution Approach 2:
The lens element combines different material properties in different regions: the bulk plastic material provides structural integrity and optical clarity, while the light-absorbing material in the peripheral strip rib structures provides reflection suppression. This composite approach maintains manufacturing simplicity while adding functional benefits.
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 solution enhances image quality by effectively reducing non-imaging light reflection, meeting the requirements for high-end optical systems and compact camera functionalities in portable electronic devices.
Implementation Method 1
The peripheral portion includes a plurality of strip rib structures and a plurality of light absorbing coatings. Each of the strip rib structures has a strip shape along a radial direction of an optical axis of the plastic lens element, and the strip rib structures are arranged around the effective optical portion. The light absorbing coatings are coated on the strip rib structures respectively.
Data Source
AI summary
A photographing lens module includes a plurality of lens elements, wherein one of the lens elements is a plastic lens element, and at least one surface of an object-side surface and an image-side surface of the plastic lens element includes an effective optical portion and a peripheral portion. The effective optical portion is aspheric. The peripheral portion surrounds the effective optical portion, and includes a plurality of strip rib structures and a plurality of light absorbing coatings. Each of the strip rib structures has a strip shape along a radial direction of an optical axis of the plastic lens element, and the strip rib structures are arranged around the effective optical portion. The light absorbing coatings are coated on the strip rib structures respectively.