Patent ID: 6296350
Filing Date: 2001-10-02
Classification: B41J

Abstract:
An inkjet printing apparatus comprising:a print cartridge including at least one resistive heating element in at least one chamber capable of containing ink and having an orifice; anda driver circuit, electrically coupled to said print cartridge, for applying to said resistive heating element a warming pulse and a firing pulse separated from one another by a delay period, said warming pulse applying an amount of energy less than an amount of energy applied by the firing pulse, said warming pulse being capable of causing said resistive heating element to warm a portion of ink provided in the chamber, said warming pulse and said delay period cooperating to form a thermal boundary layer in the ink, and said firing pulse being applied while the thermal boundary layer is in the ink and being capable of causing said resistive heating element to produce a vapor bubble in said chamber which causes a resultant droplet of the ink to be ejected from said chamber orifice with a momentum, wherein energy diffused in said thermal boundary layer cooperates with the energy applied by the firing pulse to increase the size of the thermal boundary layer prior to nucleation an thereby increase the momentum of said resultant droplet when compared with a droplet resulting when said resistive heating element receives a single firing pulse which applies an energy amount substantially equal to a combined energy amount of said warming pulse and said firing pulse.