Patent ID: 6435666
Filing Date: 2002-08-20
Classification: B41J

Abstract:
A method for operating a liquid drop emitter for emitting a series of liquid drops, said liquid drop emitter comprising a chamber, filled with a liquid, having a nozzle for emitting drops of the liquid, an actuator for applying pressure to the liquid at the nozzle, the actuator having a movable portion and exhibiting a damped resonant oscillation of fundamental period TR and a damping time constant TD, apparatus adapted to cause rapid displacements of the movable portion of the actuator in response to electrical pulses, and a controller adapted to determine parameters of the pulses, the method for operating comprising:(a) upon receipt of a command to emit a drop, applying an electrical pulse of energy E0 and pulse duration TP0, displacing the movable portion of the actuator so that a drop is emitted and a damped resonant oscillation of the actuator is initiated; (b) upon receipt of a command to emit a next drop, determining if the actuator is or is not usefully oscillating; (c) if the actuator is determined to not be usefully oscillating, returning to step (a); (d) if the actuator is determined to be usefully oscillating, waiting a time TW until the actuator is moving so as to pressurize the liquid at the nozzle; and (e) applying an electrical pulse of energy E2 and pulse duration TP2, displacing the movable portion of the actuator so that a next drop is emitted, wherein E20 and emission of the next drop advantageously uses the damped resonant oscillation of the actuator.