Patent ID: 7661785

Claim:
An ink jet head driving method for applying a drive pulse to an actuator to change capacities of a plurality of pressure chambers in which ink has been filled, ejecting an ink droplet from a nozzle formed in communication with the pressure chamber to print onto a printing medium, and moreover, controlling the number of ink droplets ejected according to the number of drive pulses to carry out gradation printing, the method comprising: making control so as to, in the case where the number of the ink droplets is smaller than a predetermined number N (where 1<N≦M and M is the number of ink droplets in maximum gradation), apply a boost pulse to amplify a pressure vibration of the pressure chamber prior to a drive pulse for ejecting a first ink droplet; and in the case where the number of ink droplets is equal to or greater than the predetermined number N, disable applying of the boost pulse.