Patent ID: 7874633
Filing Date: 2011-01-25
Classification: B41J

Abstract:
1. A printhead IC comprising: an ejection nozzle having a heater for heating printing fluid; and drive circuitry for generating print pulses and maintenance pulses for driving the heater of the ejection nozzle, the maintenance pulses comprising a series of sub-ejection pulses preceding a de-clog pulse, wherein the print signals are generated to heat the heater to form a first vapor bubble in printing fluid that causes ejection of the printing fluid from the nozzle, the de-clog pulse is generated to have lower power and longer duration than the print pulses so as to heat the heaters to form a second vapor bubble in the printing fluid which does not cause ejection, and the sub-ejection pulses are generated to have lower power than the print pulses and shorter duration than the de-clog pulse so as to heat the heater without sufficient energy to nucleate a vapor bubble in the printing fluid.