Optical Member Coating for Low Reflection and Water Droplet Shedding
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Solution Overview
Problem
Existing optical members used in cameras and other exposed surfaces face challenges with high reflectivity and adhesion of water droplets, such as raindrops, which affect image quality and functionality.
Innovation Solution
An optical member with a smooth substrate and a silicon oxide film having a fine uneven structure coated with a fluorine compound water-repellent film, featuring a sliding angle of 10° or less and a contact angle of 140° or greater, is produced through vapor phase film forming, etching, and coating processes to enhance water repellency and reduce adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface is used for the optical member, then the manufacturing process is simple, but the water droplet adhesion is high and water repellency is poor
Solution Approach 1:
The patent applies preliminary action by forming the fine uneven structure on the silicon oxide film surface before applying the water-repellent coating. This pre-structured surface enables the subsequent water-repellent layer to achieve superior water droplet repulsion performance, as the uneven structure creates multiple contact points that enhance the coating's effectiveness while maintaining manufacturing simplicity.
Solution Approach 2:
The patent employs composite materials by combining a silicon oxide film with a fluorine compound water-repellent coating. The silicon oxide provides a stable base with fine uneven structure, while the fluorine compound layer contributes hydrophobic properties. This composite structure achieves both ease of manufacture and high water repellency, resolving the technical contradiction between simple surface preparation and effective water droplet repulsion.
2Reliability
If a fine uneven structure is formed on the silicon oxide film surface, then water repellency is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by controlling the aluminum content in the silicon oxide film to be 0.25 wt% or less. This specific compositional parameter enables the formation of fine uneven structures during the sputtering process without requiring additional complex manufacturing steps. By adjusting this material parameter, the patent achieves enhanced water repellency while keeping the manufacturing process relatively simple.
Solution Approach 2:
The patent replaces mechanical surface treatment methods with a sputtering-based deposition process. Instead of mechanically creating uneven structures through etching or abrasion, the fine uneven structure is formed during the sputtering deposition of the silicon oxide film itself. This substitution reduces manufacturing complexity while achieving the desired surface morphology for enhanced water repellency.
3Manufacturing precision
If the aluminum content in the silicon oxide film is kept low (0.25 wt% or less), then the fine uneven structure quality is improved, but the film formation process becomes more difficult to control
Solution Approach 1:
The patent applies parameter changes by establishing a specific relationship between sputtering power and oxygen flow rate during film formation. By controlling these parameters together rather than independently, the patent achieves precise control over the silicon oxide film deposition process even with low aluminum content (0.25 wt% or less). This coordinated parameter control enables high-quality fine uneven structure formation while maintaining ease of manufacture through standardized process conditions.
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 optical member achieves low reflectivity, high water repellency, and effective prevention of water droplet adhesion, ensuring clear imaging and reduced surface contamination, suitable for use as a lens filter in cameras.
Implementation Method 1
a silicon oxide film provided on the optical substrate, in which the silicon oxide film has a fine uneven structure on a surface
Implementation Method 2
a water-repellent film containing a fluorine compound on the surface of the fine uneven structure
Data Source
AI summary
Provided are an optical member including an optical substrate having a smooth surface and a silicon oxide film provided on the optical substrate, in which the silicon oxide film has a fine uneven structure on a surface thereof, comprises a water-repellent film containing a fluorine compound on the surface of the fine uneven structure, and a surface of the water-repellent film has an adhesion energy of 0.2 mN/m to 6 mN/m, and a method of producing an optical member.