Spin Coating Optical Lens Peripheral Holding
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Solution Overview
Problem
Conventional spin coating methods for forming optical thin films on lenses with intense curvature or small diameters result in non-uniform film thickness, leading to reduced imaging performance, ghosting, and operability issues due to uneven film distribution and potential coating liquid reaching the back surface.
Innovation Solution
Attaching a holding member to the lens that contacts its periphery to stabilize and hold it during spin coating, preventing coating liquid from pooling at the edges and ensuring uniform film thickness across the lens surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vapor deposition method is used to form optical thin film, then high performance and low reflection in wide wavelength range is achieved, but uniform film thickness cannot be formed on lens surface with intense curvature
Solution Approach 1:
The patent replaces the vapor deposition method with spin coating, substituting a mechanical coating process with a centrifugal force-based liquid coating method. The coating liquid is applied to the lens surface and spread uniformly by centrifugal force during rotation, enabling uniform film formation on highly curved surfaces where vapor deposition fails.
Solution Approach 2:
The patent changes the physical state of the coating material from vapor phase (in vapor deposition) to liquid phase (in spin coating). This parameter change allows the coating material to flow and distribute uniformly under centrifugal force, achieving consistent film thickness on curved surfaces that cannot be achieved with vapor deposition methods.
2Manufacturing precision
If spin coating is used to form optical thin film, then uniform film thickness is achieved, but coating liquid pools at peripheral portion of lens with high D/R ratio
Solution Approach 1:
The patent introduces a dynamic element by rotating the lens at controlled speeds during coating application. The rotation speed is dynamically adjusted based on the lens's D/R ratio: higher speeds for lenses with D/R < 1.5 to prevent peripheral pooling, and lower speeds for lenses with D/R ≥ 1.5 to maintain uniform distribution. This dynamic control resolves the contradiction between achieving uniformity and preventing edge pooling.
Solution Approach 2:
The patent changes the rotational speed parameter according to the lens's geometric characteristics (D/R ratio). By adjusting this parameter dynamically based on lens type, the system achieves optimal coating uniformity for each specific lens geometry, preventing both central and peripheral thickness variations.
3Ease of manufacture
If spin coating is performed on small diameter lens, then coating is applied, but centrifugal force is insufficient and thick liquid pool appears at peripheral portion
Solution Approach 1:
The patent applies dynamic rotational control specifically tailored for small diameter lenses. By rotating these lenses at higher speeds during spin coating, sufficient centrifugal force is generated to overcome the small radius and prevent liquid pooling at the periphery, achieving uniform film formation that would otherwise be impossible on small lenses.
Solution Approach 2:
The patent uses centrifugal force generated by rotation as a counteracting force to prevent gravitational and capillary forces from causing liquid pooling. The centrifugal force acts outward to distribute the coating liquid uniformly, counterbalancing the tendency for liquid to accumulate at the peripheral portion of small diameter lenses.
4Productivity
If lens is detached from spin coater immediately after coating, then process efficiency is improved, but coating liquid is not cured and operability is reduced
Solution Approach 1:
The patent implements a preliminary curing step where the lens remains on the spin coater platter for a predetermined period after coating to allow the coating liquid to cure. This preliminary action ensures the coating is stable before handling, improving operability while maintaining efficiency by establishing a clear, automated timing protocol rather than requiring manual judgment.
Solution Approach 2:
The system allows the coating to cure automatically through the residual rotational motion and natural evaporation/curing processes while still mounted on the spin coater. The lens itself performs the curing process without additional intervention, and the system automatically determines when curing is complete based on predetermined time parameters, combining efficiency with operational safety.
5Ease of manufacture
If lens with small edge thickness is coated by spin coating, then coating is applied, but coat surface is vulnerable to touching and operability is lowered
Solution Approach 1:
The patent implements a predetermined waiting period after coating before the lens is removed from the spin coater. During this period, the coating liquid cures and hardens, making the coat surface resistant to accidental touching. This preliminary curing action protects small lenses with thin edges that would otherwise be vulnerable to damage during immediate handling.
Solution Approach 2:
The system provides a time buffer (predetermined period) that acts as a protective cushion between the vulnerable wet coating state and the handling stage. This temporal cushioning allows the coating to strengthen before the lens is manipulated, preventing damage to fragile, thin-edged lenses with freshly applied coatings.
6Manufacturing precision
If coating liquid is applied to lens surface, then optical thin film is formed, but coating liquid flows to back surface through gap between lens and lens-fixing jig
Solution Approach 1:
The patent removes the lens-fixing jig from the coating process entirely. By eliminating the jig that creates the gap through which coating liquid can escape, the system prevents back surface contamination while maintaining effective coating formation on the front surface. The lens is held in place by alternative means that do not create leakage pathways.
Solution Approach 2:
The patent introduces a coating barrier or containment structure that acts as an intermediary between the coating liquid and the back surface. This barrier prevents the coating liquid from flowing through gaps to the back surface, eliminating contamination while allowing the coating process to proceed effectively on the front surface.
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 method achieves high uniformity of film thickness and improved operability, preventing coating liquid from reaching the back surface and enhancing the stability and efficiency of optical member production, even for lenses with small diameters or thin edge thickness.
Implementation Method 1
the film is formed such that a coating liquid, which is applied to or coated on a lens, is spread thinly and uniformly by the centrifugal force brought about by rotation
Data Source
Figure 1~2
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Figure 5~6
AI summary
A method, for producing an optical member, includes attaching a holding member (12), which is used integrally with a lens (11), to the lens (11) so that the holding member is brought into contact with a periphery of the lens (11) to hold the lens (11), and then forming an optical thin film (13) on a surface of the lens (11) by a spin coating to obtain the optical member (1).