On-demand type ink-jet print head having an air flow path.

摘要

Ink in a chamber (100) is subjected to a pressure pulse by a piezoelectric transducer (101) to promote ejection of an ink droplet from a nozzle (102). In order to enhance the flight velocity and directional stability of ejected droplets, even of small size, air flow is induced around the tip of the nozzle in the direction of droplet ejection. The flow of air supplied through an inlet (108) takes place through an outlet orifice (105) and the nozzle (102) has a very thin-walled tip penetrating partially into the orifice so that a high velocity annular flow path for the air is created around the tip of the nozzle. A second embodiment has a porous member surrounding the flight pah of the ink droplets and a reservoir for keeping the porous member wetted with the primary solvent of the ink so that premature droplet drying is resisted by the high solvent vapour pressure in the vicinity of the nozzle.