Patent ID: 7753496

Claim:
An inkjet printhead comprising: an array of ink chambers, each having a nozzle and a thermal actuator respectively, the array of ink chambers defined by sidewalls extending between a nozzle plate and an underlying wafer substrate; an ink conduit between the nozzle plate and the underlying wafer, the ink conduit being in fluid communication with a plurality of the ink chambers; a plurality of ink inlets extending through the underlying wafer substrate for supplying the ink conduit, each of the ink inlets having an ink permeable trap and a vent sized so that the surface tension of an ink meniscus across the vent prevents ink leakage such that only gas bubbles vent to atmosphere through the vent; drive circuitry for providing a drive signal to the thermal actuators for ejecting ink through the corresponding nozzle, the drive circuitry having a plurality of separate drive circuits such that during use each of the drive circuits simultaneously powers a plurality of the thermal actuators; wherein, the ink chambers that respectively hold the plurality of thermal actuators simultaneously powered by one of the drive circuits are positioned such that refill ink flows through one of the ink chambers to another of the ink chambers after ejection of ink through the corresponding nozzles.