Drop Watching for Print head Testing: Real-Time Nozzle Diagnostics
DST TeamJun 16, 20252 min read
Digital Sign Technologies unveiled an innovative method for real-time nozzle diagnostics at FESPA 2025. Called drop watching, this new approach enables precise observation of ink droplet formation — all while the print head is being cleaned on the Print Head Doctor (PHD) system.
What Is Drop Watching?
Drop watching is a non-print-based method of testing print head nozzles. Instead of relying on printed test patterns or fluid curtains, this technique allows you to directly observe individual ink droplets as they are ejected, using high-resolution imaging and software analysis.
Why It’s Better Than Test Prints or Curtain Methods
Traditional Test | Drop Watching |
Requires paper or a pressure curtain | No printing required |
Hard to diagnose deflected jets | Visualizes jet angle and shape |
Time-consuming to interpret | Real-time vision analysis |
Can miss subtle jetting issues | Pixel-level droplet clarity |
How the Unified PHD + PHT System Enables Drop Watching
At the core of this system is a dual-unit setup:
The Print Head Doctor (PHD) cleans the print head using advanced flushing and piezo-assisted actuation.
The Print Head Tester (PHT) triggers the nozzles and controls waveform parameters.
Here’s how drop watching works for print head testing:
The print head is placed on a custom fixture (same one used for curtain tests).
The PHT sends controlled waveforms to fire the nozzles.
A high-speed, high-resolution camera captures droplets in real time.
Software analyzes droplet shape, velocity, consistency, and trajectory.
Results show which nozzles are performing correctly and which need further cleaning.
The Role of Fluids in Accurate Drop Watching
Drop watching is fluid-sensitive. Only DST-approved fluids can be used, as they meet strict requirements for:
Viscosity
Surface tension
Jetting reliability
Thermal behavior
Using the wrong fluid will produce misleading results or risk damaging the print head.
Key Benefits
Real-time nozzle evaluation
Reduced testing time
No wasted media or ink
Detects even subtle nozzle issues
Pairs seamlessly with the cleaning process
Learn More
Visit us to learn about our drop watching kits, approved fluids, and compatible print heads:
Have questions about implementation or compatibility? Contact us for tailored guidance.
