Speed measurement of ink droplet by using edge detection techniques

Measurement techniques for the jetting speed and the diameter of an ink droplet are discussed. For the experiment, nano silver ink with nanoparticles of approximately 10 nm diameter dissolved in DI (de-ionised) water (20 wt%) was used as the jetting material. For analysing ink droplet from a CCD (charge coupled device) camera image, the edge detection technique is used where a region of interest (ROI) is defined by a line in the direction of the ink jet. Then, the droplet speed is calculated by varying trigger delay time of strobe LED (light emitting diode) light which is synchronized with respect to the firing signal for jetting. Finally, the measured speed results using the edge detection are compared with the results from particle analysis based on the binary image.