Liquid ejection system including drop velocity modulation

A continuous ejection system includes a chamber containing liquid under pressure sufficient to eject a liquid jet through a nozzle. A drop formation device modulates the jet causing portions to break into drop pairs including first and second drops separated in time on average by a drop pair period. A charging device includes a varying electrical potential source providing a waveform including first and second distinct voltage states and a period equal to the drop pair period. The charging device produces first and second charge states on first and second drops of the drop pair, respectively. A drop velocity modulation device varies a relative velocity of first and second drops of selected drop pairs causing first and second drops of selected drop pairs to form combined drops having a third charge state. A deflection device causes the first, second, and combined drops to travel along different paths.