Patent ID: 7914115

Claim:
A printhead for an inkjet printer, the printhead comprising: a wafer assembly defining a plurality of spaced apart groups of ink supply channels and a plurality of groups of ink ejection nozzle arrangements in fluid communication with respective ink supply channel groups, each ink ejection nozzle arrangement comprising: a nozzle chamber structure mounted to the wafer assembly, and defining a nozzle chamber for receiving ink from an ink supply channel and an ink ejection port through which ink in the nozzle chamber is ejected; an anchor extending from the wafer assembly in a location external to the nozzle chamber; and an elongate thermal actuator mechanism extending from the anchor and into the nozzle chamber, the thermal actuator mechanism comprising an elongate arm which terminates in a free end within the nozzle chamber and a pair of layers of conductive material located on either side of the elongate arm, one of the layers being connected to a current supply for causing a differential thermal expansion in the elongate thermal actuator mechanism so that the free end of the arm is moved to eject ink in the nozzle chamber through the ink ejection port; wherein a pit is defined adjacent each nozzle chamber structure for catching ink and thereby impeding spilt ink from spreading across the printhead, and the ink ejection nozzle arrangements of each group are arranged in a pair of rows, with the elongate thermal actuator mechanism of ink ejection nozzle arrangements of a first row extending away from the elongate thermal actuator mechanism of ink ejection nozzle arrangements of a second row.