Abstract: Method of operating an inkjet printhead for printing on a substrate; the printhead having a chamber communicating with a nozzle for ejection of ink droplets and with a supply of ink; the printhead further comprising electrically actuable means associated with the chamber and actuable a plurality of times in accordance with print tone data, thereby to eject a corresponding number of droplets to form a printed dot of appropriate tone on the substrate; the method comprising the steps of applying a plurality of electrical signals to the electrically actuable means in accordance with the print tone data, the time delay between application of successive signals being such that any variation in the average velocity at which corresponding droplets travel to the substrate to form said printed dot remains below that which would lead to defects in the printed image detectable by the naked eye, regardless of the number of said droplets ejected to form said printed dot.

Abstract: A method of operating an inkjet printhead for printing on a substrate, the printhead having an array of channels; a series of nozzles which communicate respectively with said channels for ejection of droplets therefrom; connection means for connecting the channels with a source of ink; and electrically actuable means associated with each channel and actuable a plurality of times in accordance with print tone data, thereby to eject a corresponding number of droplets to form a printed dot of appropriate tone on the substrate, the method comprising the steps of: applying one or a plurality of electrical signals to the electrically actuable means associated with a channel in accordance with the print tone data, the duration of each signal being chosen such that the velocity of the corresponding ejected droplet is substantially independent of (a) whether or not channels in the vicinity of said selected channel are similarly actuated to effect drop ejection simultaneously with drop ejection from said selected chann