Cross-Talk Reduction by Smart Delay Firing

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As ink jet arrays become larger, the cross-talk between closely spaced firing channels becomes more severe resulting in an adverse impact on print quality. A method of addressing this problem applicable to any type of DOD ink jet without making any physical changes to the individual jet design and with only minimal changes to the array configuration is described.The individual channels of the array are divided into N interspersed groups and the permitted firing time of each group has its own small time delay, δ. An optimum delay is calculated for each group so that, when all channels are fired, there is a maximum amount of cross-talk cancellation. Because the firing channels are the source of an acoustic wave train predominantly at a resonant frequency of the channel, the interaction with other firing channels depends strongly on the phase relationship with the arriving wave. For any given print-head, a number of basic experimental measurements are made and the data used as input to a computer model, which calculates the change in drop velocity as a function of the delays for a channel near the centre of the array when all channels are firing. The basic equations and an outline of the computation are shown.