Patent ID: 6126278
Filing Date: 2000-10-03
Classification: B41J

Abstract:
An ink jet head system for printing characters on a printing sheet via ink droplets upon application of a driving voltage, comprising:a cavity plate in which a plurality of ink chambers are formed, each ink chamber having a length;a sheet member adhered on an upper face of the cavity plate to cover upper faces of the ink chambers;a plurality of piezoelectric elements, each piezoelectric element being disposed on the sheet member at a location corresponding to each ink chamber, each piezoelectric element being driven to pressurize the corresponding ink chamber and to generate a pressure wave in ink by applying the driving voltage;a nozzle plate having nozzles, each nozzle communicating with each ink chamber, through which the ink droplets are ejected from the ink chambers to print characters when the piezoelectric element is driven; andmeans for driving the plurality of piezoelectric elements, the means for driving being able to drive only one of the plurality of piezoelectric elements, the means for driving also being able to drive multiple piezoelectric elements at substantially the same time, the means for driving driving at least one of the piezoelectric elements in accordance with a condition; n.times.T.ltoreq.P.ltoreq.(n+0.4).times.T, wherein the ""n"" is an integral odd number, between a pulse width P of the driving voltage applied to said piezoelectric element and a time T needed for the pressure wave of ink, which generates when the ink chamber is pressurized through the piezoelectric element, to travel through the ink chamber by the length, and said piezoelectric element is driven under said condition, such that an ejecting velocity of the ink droplet is set in a predetermined range regardless of whether the means for driving drives only one piezoelectric element or multiple piezoelectric elements.