Patent ID: 6969145

Claim:
A printhead for an ink jet printer, the printhead including: a substrate carrying an array of nozzles for ejecting ink onto media to be printed, each nozzle incorporating a bend actuator for ejecting ink from a nozzle chamber, the bend actuator being arranged to cause refilling of the nozzle chamber from a supply of ink after ink ejection; an apertured guard positioned over at least one of the nozzles such that ejected ink passes through an aperture and onto the media; the guard and the at least one nozzle at least partially defining a containment formation for isolating leaked or misdirected ink from the at least one nozzle from at least some of the other nozzles in the array; means to detect a predetermined amount of ink in the containment formation; and nozzle fault circuitry connected to the detection means, the nozzle fault circuitry arranged to stop supply of ink to the at least one nozzle by disabling the associated bend actuator if the predetermined amount of ink is detected by the detection means.