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Drop Watching for Printhead Testing: Real-Time Nozzle Diagnostics

  • DST Team
  • Jun 16
  • 2 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 printhead is being cleaned on the Print Head Doctor (PHD) system.


Unified Print Head Doctor and Print Head Tester system demonstrating drop watching setup at FESPA 2025, with dual monitors, fluid lines, and touchscreen controls.

What Is Drop Watching?


Drop watching is a non-print-based method of testing printhead 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 printhead 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 printhead testing:


  1. The printhead is placed on a custom fixture (same one used for curtain tests).

  2. The PHT sends controlled waveforms to fire the nozzles.

  3. A high-speed, high-resolution camera captures droplets in real time.

  4. Software analyzes droplet shape, velocity, consistency, and trajectory.

  5. 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 printhead.


Key Benefits


  1. Real-time nozzle evaluation

  2. Reduced testing time

  3. No wasted media or ink

  4. Detects even subtle nozzle issues

  5. Pairs seamlessly with the cleaning process


Learn More


Visit us to learn about our drop watching kits, approved fluids, and compatible printheads:


Have questions about implementation or compatibility? Contact us for tailored guidance.

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