What is dynamic printhead

Real-time drop analysis for inkjet printing


KRÜSS presents the new Drop Shape Analyzer - DSA Inkjet at the InPrint in Munich

At InPrint from November 12th to 14th in Munich, KRÜSS will present the new Drop Shape Analyzer - DSA Inkjet. The measuring instrument analyzes the properties and flight behavior of ink droplets after they have emerged from the printhead. While inkjet technology in the home and office is declining, industrial use is growing rapidly. Common problems such as nozzles drying out and blurred print images also occur in large-scale use and cause considerable costs. During ink development and quality assurance, the interaction between the printhead control and the ink must therefore be perfectly adjusted and monitored. The DSA Inkjet was specially designed for this task. With its own printer electronics for compatible print heads or via a trigger function, it communicates directly with the print head installed in the instrument and analyzes the ink drops in real time.

Innovative technology for mapping and analyzing the drops

After the printhead has been inserted into the instrument with simple steps, the intuitive waveform editor for compatible printheads realistically simulates the electronic control in one printing process. The microscope optics show the jet of drops sharply and with high contrast. In order to be able to precisely analyze ink drops of a few picoliters at flight speeds of up to 40 m / s, the DSA Inkjet uses an ingenious method: two different colored light flashes in short succession ensure a double exposure of the drop in a single video image from a color camera. By separating the color channels, discrete individual images of the drops are obtained every few milliseconds.


The method opens up unprecedented opportunities to record the flight of drops live, to analyze drops automatically and to obtain result parameters relevant to the print quality. The software-controlled measurement provides mean values ​​for volume and speed of the drop, flight path (deviation from the vertical), length of the ligament and number of partial drops, which is important when satellite drops occur. The data are generated as direct feedback on the dynamically adjustable printing parameters and are particularly suitable for checking an ink or optimizing the printing process. In addition, automation programs that are easy to create enable measurements under repeatable conditions in order to test ink formulations in a standardized manner.



Observation of the nozzles and automatic determination of the image scale

Wetting the printhead during printing can deflect the jet of droplets and clog the nozzles due to drying out. In order to make unwanted ink drops visible on the rows of nozzles, a separate optic observes the nozzles from below. Another innovative development makes it easier to measure real drop dimensions such as the volume or length of the ligament. For this purpose, the image scale is automatically determined with the aid of a calibration grid projected regularly into the camera image. This eliminates the need for image calibration when changing the zoom, which saves time and ensures reliable results.



Versatile device components for practice

The DSA Inkjet is designed for easy, versatile and safe use. Inserting the printhead and directing the focus on individual nozzles is a matter of a few simple steps thanks to the three-dimensional fine positioning. The instrument is also provided with a storage tank to supply the print head with ink even during long-term measurements, with the drops being collected in a waste container. A suction device prevents harmful vapors. Thanks to a UV protective cover, UV-curing inks such as those used for 3D printing can also be examined.

Drop Shape Analyzer - DSA Inkjet for real-time analysis of ink drop

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