Abstract: An ink supply system for an inkjet printer. The ink supply system includes an ink reservoir and a pressure-regulating chamber. The pressure-regulating chamber has an inlet port, an outlet port, an air vent open to atmosphere and a float valve for maintaining a predetermined level of ink in the chamber. The float valve is biased towards a closed position by a positive ink pressure from the ink reservoir at the inlet port.

Abstract: A method is provided of controlling a printhead having nozzles which discharge ink by application of a firing pulse to respective actuators. The actuators are connected in groups to a power source which applies the firing pulses. In the method firing pulses are applied to each group of the actuators in turn to discharge ink from the nozzles in each group. The firing pulses are applied to the subsequent groups so that the fired nozzles are physically separated in the printhead as far as possible from the nozzles fired in the immediately prior group and the immediately subsequent group.