Contact Angle Measurement via Inclined Shadow Projection
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Solution Overview
Problem
Current contact angle measuring devices are expensive, require large surface areas, have low automation, and are not suitable for measuring complex geometries or industrial use due to issues with surface recognition and reflective materials, limiting their effectiveness in quality assurance for metal and plastic surfaces.
Innovation Solution
A contact angle measuring device with a lighting system that generates a parallel light beam, an inclined shadow area, and an image capturing device, allowing for precise calculation of the contact angle by creating a symmetrical and distorted drop shadow image, which enables accurate surface energy determination without the need for complex adjustments or human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial contact angle measuring devices based on sessile drop method are used, then contact angle measurement capability is achieved, but device cost and required surface area become excessively high
Solution Approach 1:
The patent creates an optical copy (shadow image) of the liquid drop on a shadow surface rather than directly imaging the drop itself. This shadow copy technique allows measurement of contact angle using simpler optical components, reducing device complexity and cost while maintaining measurement capability
Solution Approach 2:
The patent introduces a shadow surface as an intermediary element between the light source and the image capture device. This intermediary surface converts the three-dimensional drop shape into a two-dimensional shadow pattern that can be analyzed, simplifying the overall measurement system
2Measurement precision
If traditional shadow image method with perpendicular shadow surface is used, then contact angle can be measured, but surface recognition fails on reflective materials
Solution Approach 1:
The patent tilts the shadow surface at an angle between 10-30 degrees relative to the measurement object surface, creating an asymmetric configuration. This asymmetric shadow surface orientation prevents direct reflection of light from the measurement object into the image capture device, enabling reliable surface recognition on reflective materials
Solution Approach 2:
The patent changes the spatial dimension and orientation of the shadow surface from perpendicular to tilted relative to the measurement object surface. This dimensional change in the shadow surface orientation separates the reflected light path from the imaging path, solving the reflective material problem
3Measurement precision
If test inks are used for wettability control, then surface energy can be checked, but the method contaminates surfaces and has limited applicability
Solution Approach 1:
The patent uses optical shadow copying instead of direct contact with test inks. By projecting light to create shadow images of liquid drops on a shadow surface, the method eliminates the need for test ink application, preventing surface contamination while maintaining surface energy measurement capability
Solution Approach 2:
The patent replaces the mechanical application of test inks with an optical shadow imaging system. This substitution eliminates physical contact between testing materials and the measurement object surface, removing contamination risks and extending measurement system longevity
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 device provides accurate and efficient measurement of contact angles on various surfaces, including complex geometries, with improved automation and mobility, reducing errors and operational costs while ensuring reliable quality assurance.
Implementation Method 1
The light beam projects a silhouette of the drop onto the shadow area
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Device for measuring the contact angle of a liquid droplet (7) on a material surface. The shadow of a droplet of a test liquid is projected onto an inclined shadow surface (8). An image of the droplet on the shadow surface is captured by an image acquisition device (1), and the contact angle is calculated from the image and the known inclination angle of the shadow surface. A suitable method for this purpose is also disclosed.