Ink-Jet Cartridge Lifetime

Extensive examination of thermal ink-jet cartridges has revealed that their maximum lifetime is limited by two major mechanisms: The first is the deterioration of the heaters caused by the ink-jet propelling bubble combined with the high temperature of operation of the heaters. The second is deterioration caused by direct current leakage from the heater through the ink chamber creating unwanted electrolytic byproducts. To eliminate both of these effects, it is proposed to eliminate the electrical heaters used to generate the propelling bubble and replacing them by electrodes passing a high-frequency current through the printing ink to form a propelling bubble. To evaluate this system, it is necessary to experimentally determine the electrical characteristics of the ink to determine the efficiency of heating by the applied current, in the range from 100 KHz to 200 MHz. It was found that standard ink-jet inks, now in use, can be efficiently coupled to the drive transistors within this range without altering ink composition