Printhead with variable nozzle firing sequence

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

an array of ink ejection nozzles;

a plurality of actuators arranged such that one of the actuators corresponds to one of the nozzles respectively in order to eject ink therethrough;

a drive circuitry for receiving print data from a print engine controller and distributing fire signals to the actuators; wherein during use,

the array of nozzles are fired in a firing sequence determined by the drive circuitry such that the firing sequence for one line of print is different to the firing sequence for a subsequent line of print,

wherein the drive circuitry has nozzle enable latches for each of the actuators respectively, each nozzle enable latch holding a fire signal for the nozzles selected to fire in the next line of print, and shift registers for loading the fire signals to the latches in accordance with the print data received from the print engine controller, the shift registers being configured to load the latches of the selected nozzles for one line of print while the nozzles selected for the previous line of print are firing.

2. A printhead according to claim 1 wherein the array of nozzles is supplied with different colored inks and the drive circuitry determines that nozzles of the same color selected to fire in one line of print, are maximally spaced from each other.

3. A printhead according to claim 2 wherein the nozzles of the same color selected to fire in one line of print are fired simultaneously.

4. A printhead according to claim 1 wherein the nozzles, the actuators and the drive circuitry are all fabricated on a single monolithic wafer substrate.

5. A printhead according to claim 4 wherein the printhead is a pagewidth printhead.

6. A printhead according to claim 4 wherein the array has more than 1000 nozzles.

7. A printhead according to claim 6 wherein the shift registers load the latches of the nozzles selected for printing the next line of print in less than 200 microseconds.

8. A printhead according to claim 2 wherein the drive circuitry ensures that a minimum spacing of five nozzles between simultaneously firing nozzles of the same color.

9. A printhead according to claim 2 wherein the drive circuitry divides the nozzles of the same color into groups of less than twenty, and only allows a maximum of one nozzle in each of the groups to fire when printing a single print line.

10. A printhead according to claim 9 wherein the drive circuitry indexes through all the nozzles in each group before firing any nozzle in one group twice.