Printhead having nozzle arrangements with radial actuators

1. A printhead for an inkjet printer, the printhead comprising

a wafer that defines a plurality of nozzle chambers and ink supply channels in fluid communication with the nozzle chambers to supply the nozzle chambers with ink;

an ink ejection port associated with each nozzle chamber; and

a series of actuators associated with each nozzle chamber and radially positioned with respect to the nozzle chamber, the actuators being operable so that, when activated, they are displaced into the nozzle chamber to generate an ink meniscus at the ink ejection port and, when deactivated, return to an original position resulting in the necking and breaking of the ink meniscus to eject an ink drop.

2. A printhead as claimed in claim 1 , in which the nozzle chambers and the ink supply channels are the result of an etching process carried out on the wafer.

3. A printhead as claimed in claim 1 , in which each actuator comprises an electrically conductive heater element in a layer of a plastics material, the heater element being positioned in the plastics material to cause uneven heating and resulting uneven expansion so that the actuators bend into the nozzle chamber.

4. A printhead as claimed in claim 3 , in which each heater element is serpentine to accommodate expansion of the actuators.

5. A printhead as claimed in claim 1 , in which the wafer incorporates a CMOS layer that includes power and drive circuits for the actuators.

6. A printhead as claimed in claim 1 , in which each actuator includes a polytetrafluoroethylene (PTFE) layer, and an internal serpentine copper core which is heated when carrying current to bend the actuators.

7. A printhead as claimed in claim 1 , wherein bridges extend radially from a rim defining the ink ejection ports and between adjacent actuators.