Patent ID: 7264337

Claim:
A method of ejecting ink comprising: (a) filling a rear end of a nozzle with ink using a capillary force, the rear end of the nozzle being surrounded by a hydrophilic layer; (b) forming an electric field directed toward an outlet of the nozzle on a front end of the nozzle, the front end of the nozzle being surrounded by a hydrophobic layer; (c) modifying a magnitude and location of the electric field to modify a surface property of the hydrophobic layer to hydrophilic and vary a surface tension of the ink to separate at least one ink droplet having a predetermined volume from the ink within the front end of the nozzle and to move the at least one separated ink droplet within the front end of the nozzle toward the outlet of the nozzle; and (d) ejecting the separated ink droplets through the outlet of the nozzle.