Patent ID: 6378972
Filing Date: 2002-04-30
Classification: B41J

Abstract:
A drive method for an on-demand multi-nozzle ink jet head including an ink chamber filling ink therein and defined by a diaphragm and an orifice plate formed with orifices therein, a piezoelectric element which is attached to the diaphragm and deforms when a drive pulse is applied to the piezoelectric element, thereby varying pressure in the ink chamber, an ink channel for supplying ink to the ink chamber, and a common ink channel in fluid communication with the ink channel, the method comprising the steps of:determining a unit pulse having a pulse width, the pulse width being determined while referring to a period of Helmholtz natural oscillation and being substantially equal to the period of the Helmholtz natural oscillation; determining an off duration paused between two successive unit pulses, the unit pulse and subsequent off duration forming a drive pulse for applying to the piezoelectric element, the off duration being equal to or less than one fourth of the pulse width of the unit pulse; and applying a predetermined number of drive pulses in succession to the piezoelectric element when an instruction is given to increase a size of dot on a print medium.