Patent ID: 7300125

Claim:
An inkjet head printing device, comprising: an inkjet head that has an ink flow channel unit including a plurality of nozzles for ejecting ink and a plurality of pressure chambers respectively provided for the plurality of nozzles, and a piezoelectric actuator unit including a piezoelectric sheet, a plurality of electrodes and a common electrode, the plurality of electrodes being respectively located oppositely to the plurality of pressure chambers, each of the plurality of electrodes applies a voltage to the piezoelectric sheet to change a volumetric capacity of corresponding one of the plurality of pressure chambers and to eject ink from corresponding one of the plurality of nozzles; a pulse generator that determines whether each of the plurality of nozzles ejects the ink or not, and determines an amount of ink to be ejected from each of the plurality of nozzles based on gray scale information in image data to be formed, wherein the pulse generator determines first pulse patterns to be applied to electrodes respectively corresponding to nozzles determined to eject the ink by the pulse generator, the first pulse patterns respectively corresponding to amounts of ink of the nozzles determined to eject the ink by the pulse generator, each of the first pulse patterns having a first potential which causes each of the plurality of nozzles to eject the ink, and wherein the pulse generator determines a second pulse pattern to be applied to at least one of electrodes respectively corresponding to nozzles determined not to eject the ink by the pulse generator, the second pulse pattern having a second potential which does not cause each of the plurality of nozzles to eject the ink; and a memory that stores a plurality of kinds of pulse patterns which respectively correspond to a plurality of kinds of gray scale levels, wherein the pulse generator determines the first pulse patterns by selecting one of the plurality of kinds of patterns stored in the memory based on the gray scale information in the image data, wherein the pulse generator determines the second pulse pattern based on the plurality of kinds of pulse patterns stored in the memory, and wherein the second pulse pattern is determined based on the densest gray scale level of gray scale levels of pixels in the image data.