Dynamical Behaviour of Piezoelectrical Cantilever Beams in an Inkjet Printhead

In this paper, the functional principle of an inkjet printhead for different applications is explained. Using displacement effects the printhead is insensitive to gas bubbles and can be used for various fluids to generate droplets with volumes of less than 100 picoliters. The actuator is a composite of a piezoelectrical ceramic and a passive silicon beam. For tests, several systems with different geometries and a physical resolution up to 150 dpi were built. To verify the dynamical behaviour of the printhead in dependence of the dosing fluid, several measurement configurations and two test stations are used. With a stroboscopic vision system the generated droplets can be visualised and the diameter and the velocity of the droplets can be measured. The dynamical behaviour of the actuators in the fluid can be detected with a Laser-Doppler-Vibrometer. Thus, possible interactions between the single actuators can be measured. At last, the results of the measurements contribute to the verification of a theoretical compact model for a system simulation. This simplified model allows short time parameter studies to optimize the fluid flow, the activation signals, the interactions between the actuators and the geometry.