Patent ID: 8382259

Claim:
A method of ejecting liquid drops comprising: providing liquid under pressure sufficient to eject a liquid jet through a nozzle of a liquid chamber; modulating the liquid jet to selectively cause portions of the liquid jet to break off into one or more pairs of drops traveling along a path using a drop formation device associated with the liquid jet, each drop pair separated on average by a drop pair period, each drop pair including a first drop and a second drop; modulating the liquid jet to selectively cause portions of the liquid jet to break off into one or more third drops traveling along the path separated on average by the same drop pair period using the drop formation device, the third drop being larger than the first drop and the second drop; providing a charging device including: a charge electrode associated with the liquid jet; and a source of varying electrical potential between the charge electrode and the liquid jet, the source of varying electrical potential providing a waveform, the waveform including a period that is equal to the drop pair period of formation of drop pairs or third drops, the waveform including a first distinct voltage state and a second distinct voltage state; synchronizing the charging device with the drop formation device to produce a first charge to mass ratio on the first drop of the drop pair, produce a second charge to mass ratio on the second drop of the drop pair, and produce a third charge to mass ratio on the third drop, the third charge to mass ratio being substantially the same as the first charge to mass ratio; and causing the first drop of the drop pair having the first charge to mass ratio to travel along a first path, causing the second drop of the drop pair having the second charge to mass ratio to travel along a second path, and causing the third drop having a third charge to mass ratio to travel along a third path using a deflection device.