Selecting a material for use as the expansive element

摘要

The invention relates to an ink jet print head comprising a plurality of nozzles adapted to eject drops of ink through an opening towards a surface to be printed. Each nozzle has a nozzle chamber adapted for receiving ink via a conduit. The nozzle chamber is defined by a floor portion, an upwardly extending peripheral floor sidewall and a roof portion having a depending peripheral roof sidewall. The floor and roof are arranged to at least partially overlap in a telescopic manner. Each nozzle also comprises an actuator arranged to move the roof portion upwardly and downwardly relative to said floor portion so as to eject ink drops toward a surface to be printed. The distance between the telescopically overlapped sidewalls is such that when the chamber is in use and ink is located within the chamber, surface tension provides for sealing of the space between the sidewalls so as to at least reduce leakage of ink through the space.