Measurement of inkjet first-drop behavior using a high-speed camera

Area of Science:

• Materials Science
• Manufacturing Engineering
• Fluid Dynamics

Background:

• Drop-on-demand inkjet printing offers precise deposition for printed electronics.
• A non-jetting idle time is necessary for positioning, but can cause abnormal first-droplet behavior.
• This abnormal behavior negatively impacts printing quality and necessitates proper evaluation.

Purpose of the Study:

• To develop a method for evaluating first-droplet failure in inkjet printing.
• To characterize the behavior of initial droplets after a non-jetting pause.
• To investigate methods for suppressing first-droplet dissimilarity.

Main Methods:

• Utilizing a high-speed camera with an acquisition frame rate as an integer multiple of the jetting frequency.
• Directly comparing droplet locations to analyze first-drop behavior.
• Evaluating the impact of applying a sub-driving voltage during the non-jetting pause time.

Main Results:

• The high-speed camera method enables direct comparison and characterization of first-drop behavior.
• First-droplet dissimilarity was observed after non-jetting pause times.
• Applying a sub-driving voltage during the pause effectively suppressed first-droplet dissimilarity.

Conclusions:

• High-speed imaging is a viable technique for evaluating first-droplet anomalies in inkjet printing.
• First-droplet behavior is sensitive to non-jetting pause durations.
• Sub-driving voltage presents a promising strategy to mitigate first-droplet issues and improve printing quality.