Patent ID: 6896346

Claim:
A method for operating a liquid drop emitter for emitting liquid drops of substantially different volumes having substantially a same target velocity v 0 , said liquid drop emitter comprising a chamber, filled with a liquid, having a nozzle for emitting drops of the liquid, a thermo-mechanical actuator having a moveable portion within the chamber for applying pressure to the liquid at the nozzle, and apparatus adapted to apply heat pulses to the thermo-mechanical actuator, the method for operating comprising: (a) applying a first heat pulse having a first power P 1 , first pulse duration τ p1 , and first energy E 1 =P 1×τ p1 , displacing the movable portion of the actuator so that a drop is emitted having a first drop volume V d1 , and traveling substantially at the target velocity v 0 ; and (b) applying a second heat pulse having a second power P 2 , second pulse duration τ p2 , and second energy E 2 =P 2 ×τ p2 , displacing the movable portion of the actuator so that a drop is emitted having a second drop volume V d2 and traveling substantially at the target velocity v 0 , wherein V d2 >V d1 , E 2 >E 1 , τ p2 >τ p1 and P 2 <P 1 .