Drop placement error reduction in electrostatic printer

Abstract

A group timing delay device shifts the timing of drop formation waveforms supplied to drop formation devices of one of first and second nozzle groups so that print drops from the nozzle groups are not aligned relative to each other along a nozzle array direction. A charging device includes a common charge electrode associated with liquid jets from the nozzle groups and a source of varying electrical potential between the charge electrode and liquid jets which provides a charging waveform that is independent of a print and non-print drop pattern. The charging device is synchronized with the drop formation devices and the group timing delay device to produce a print drop charge state on print drops of a drop pair, a first non-print drop charge state on non-print drops of the drop pair, and a second non-print drop charge state on third drops.