Spin Coating Concave Optical Surfaces Reducing Solution Wastage
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Solution Overview
Problem
Conventional spin coating methods result in significant solution wastage, especially for high-cost solutions that require thick coatings, as they fail to efficiently distribute the coating uniformly across the optical article surface.
Innovation Solution
The method involves dispensing a coating solution along the edge of a concave optical article surface facing upwards, allowing it to flow centrally under gravity before spinning, ensuring the surface is wetted twice, which reduces wastage and allows for a uniform layer with a lower dispensed volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional spin coating method is used to dispense coating solution centrally on a rotating article, then the solution spreads over the entire surface, but significant solution wastage occurs especially for high-cost solutions and thick coatings
Solution Approach 1:
The patent applies preliminary action by dispensing the coating solution along the edge of the concave surface before the spinning step, allowing the solution to flow centrally and wet the surface in advance. This pre-wetting action ensures that when spinning occurs, less solution is needed to achieve complete surface coverage, thereby reducing solution wastage while maintaining adequate coating quantity
Solution Approach 2:
The patent inverts the conventional approach by dispensing solution along the edge rather than at the center, and by utilizing the concave surface geometry to guide solution flow. This inversion allows the solution to naturally distribute across the surface through gravity-driven flow before spinning, reducing the total volume needed and minimizing wastage
2Manufacturing precision
If conventional spin coating dispenses solution centrally during rotation, then coverage is achieved, but the solution does not wet the surface efficiently requiring higher dispensed volume
Solution Approach 1:
The solution is dispensed along the edge and allowed to flow centrally before spinning, creating a preliminary wetting layer that ensures uniform distribution. This pre-distribution action achieves manufacturing precision by ensuring the entire surface is wetted before the spinning step, while reducing the total volume required compared to conventional methods
Solution Approach 2:
The patent utilizes the concave curvature of the optical article surface to guide the solution flow from the edge toward the center. This curvature advantage enables efficient solution distribution and wetting across the entire surface area, achieving uniform coating with reduced solution volume
3Manufacturing precision
If high-cost solutions are used for thick coatings, then desired coating thickness is achieved, but solution wastage increases significantly
Solution Approach 1:
By dispensing solution along the edge and allowing it to flow centrally before spinning, the method creates an initial coating layer that ensures thorough surface wetting. This preliminary action maintains desired coating thickness while reducing the total volume of expensive solution required, thereby minimizing wastage
Solution Approach 2:
The patent changes the dispensing parameters from central location to edge location, and from during-rotation dispensing to pre-spin dispensing. These parameter changes enable achieving the same coating thickness with reduced solution volume, reducing wastage of high-cost materials
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 significantly reduces solution wastage while achieving uniformity and full coverage with a lower volume of coating solution, particularly beneficial for viscous and expensive solutions, by ensuring the surface is wetted twice during the process.
Implementation Method 1
the solution deposited along the edge of the concave surface flows under the effect of gravity towards the centre of the surface
Implementation Method 2
spinning said article to force the solution back to the edge of the concave face
Data Source
AI summary
A method for spin coating a surface of an optical article, includes the steps of:selecting as the optical article an article (10) with a concave face (12) able to adopt a facing up position in which its uppermost portion is an edge (15) and selecting the concave face as the surface to be coated;dispensing a predetermined volume of a coating solution (18) on the concave face (12) along the edge (15), the concave face (12) facing up and the solution being dispensed in a top down manner;waiting with no motion of the article (10) for the solution to flow on the concave face (12) until it collects centrally; andspinning the article (10) to force the solution back to the edge (15) of the concave face (12).