Abstract: A droplet of ink 11 is expelled from a nozzle in a wall, so as to strike a printing medium, by suddenly moving the wall towards the ink 11 with which it is in contact. This movement is effected by energizing a piezoelectric sleeve. The ink droplet is expelled by virtue of the inertia of the ink resisting the movement of the wall and creating pressure. Practical embodiments are described in which the wall containing the nozzle is formed by the tapered end of a capillary tube.

Abstract: An ink-jet printer includes a reservoir filled with ink and a duct communicating with the reservoir and also filled with ink. The duct has an end portion with a capillary nozzle for projecting the ink and an intermediate portion between the reservoir and the end portion. Transducer means are associated with the end portion of the duct for generating a first pressure wave in the ink, which is directed towards the nozzle and causes a droplet of ink to be discharged through the nozzle. A second pressure wave associated with the first pressure wave is directed towards the intermediate portion of the duct and, to substantially absorb the energy of this second wave, the printer further includes an elongate damper which extends in contact with the ink in only the intermediate portion of the duct.