Method of operating pulsed droplet deposition apparatus

Claim 1

The method of operating an apparatus comprising an array of parallel liquid containing channels, a plurality of nozzles respectively communicating with said channels, electrically actuatable means for applying energy pulses to the liquid in selected ones of said channels to effect expulsion of drops of said liquid therefrom, and liquid supply means for replenishing the liquid expelled from said channels by operation of said electrically actuatable means, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex in the direction in which said drop being formed is moving and is moving in a direction reverse to that in which said drop being formed is moving thereby to effect detachment of said drop, each of said second pulses being of lower energy content than said first energy pulses and of insufficient energy content itself to cause ejection of a drop of liquid from the corresponding nozzle, the energy content of each of said first energy pulses being sufficient to cause ejection of a drop of liquid from the corresponding nozzle.

Claim 2

The method of operating an apparatus comprising an array of parallel liquid containing channels, a plurality of nozzles respectively communicating with said channels, electrically actuatable means for applying energy pulses to the liquid in selected ones of said channels to effect expulsion of drops of said liquid therefrom, and liquid supply means for replenishing the liquid expelled from said channels by operation of said electrically actuatable means, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex in the direction in which said drop being formed is moving and is moving in a direction reverse to that in which said drop being formed is moving thereby to effect detachment of said drop, each of said second pulses being of lower energy content than said first energy pulses and of insufficient energy content itself to cause ejection of a drop of liquid from the corresponding nozzle, the energy content of each of said first energy pulses being sufficient to cause ejection of a drop of liquid from the corresponding nozzle.

Claim 3

The method of operating an apparatus comprising an array of parallel liquid containing channels, a plurality of nozzles respectively communicating with said channels, electrically actuatable means for applying energy pulses to the liquid in selected ones of said channels to effect expulsion of drops of said liquid therefrom, and liquid supply means for replenishing the liquid expelled from said channels by operation of said electrically actuatable means, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex in a direction in which said drop being formed is moving, and then operating said electrically actuatable means to apply a third energy pulse to the liquid in each of said selected channels to cause said meniscus to move in a direction reverse to movement of said drop attached thereto thereby to effect detachment of said drop, each of said second and third energy pulses being of insufficient energy content to cause ejection of a drop of liquid from the corresponding nozzle.

Claim 4

The method of operating an apparatus comprising an array of parallel liquid containing channels, a plurality of nozzles respectively communicating with said channels, electrically actuatable means for applying energy pulses to the liquid in selected ones of said channels to effect expulsion of drops of said liquid therefrom, and liquid supply means for replenishing the liquid expelled from said channels by operation of said electrically actuatable means, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex in a direction in which said drop being formed is moving, and then operating said electrically actuatable means to apply a third energy pulse to the liquid in each of said selected channels to cause said meniscus to move in a direction reverse to movement of said drop attached thereto thereby to effect detachment of said drop, each of said second and third energy pulses being of insufficient energy content to cause ejection of a drop of liquid from the corresponding nozzle.

Claim 5

The method of operating an apparatus comprising an array of parallel liquid containing channels forming an array direction, each of said channels having a longitudinal axis, channel dividing side walls respectively separating successive channels of said array of channels, said side walls being formed with piezoelectric material poled in a direction normal both to said array direction and said channel axes and each having channel facing surfaces on opposite sides thereof, an electrode respectively provided on each of said channel facing surfaces, a plurality of nozzles respectively communicating with said channels, and electrically actuatable means for applying voltage pulses to the electrodes of the side walls of selected ones of said channels to deflect said side walls in shear mode thereby to impart energy pulses to the liquid in said selected channels to expel respective drops of said liquid from the nozzles of said channels, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex is a direction in which said drop being formed is moving and is moving in a direction reverse to that in which said drop being formed is moving thereby to effect detachment of said drop, each of said second pulses being of lower energy content than said first energy pulses and of insufficient energy content itself to cause ejection of a drop of liquid from the corresponding nozzle.

Claim 6

The method of operating an apparatus comprising an array of parallel liquid containing channels forming an array direction, each of said channels having a longitudinal axis, channel dividing side walls respectively separating successive channels of said array of channels, said side walls being formed with piezoelectric material poled in a direction normal both to said array direction and said channel axes and each having channel facing surfaces on opposite sides thereof, an electrode respectively provided on each of said channel facing surfaces, a plurality of nozzles respectively communicating with said channels, and electrically actuatable means for applying voltage pulses to the electrodes of the side walls of selected ones of said channels to deflect said side walls in shear mode thereby to impart energy pulses to the liquid in said selected channels to expel respective drops of said liquid from the nozzles of said channels, said method comprising operating said electrically actuatable means to apply first energy pulses to the liquid in said selected channels to expel liquid from the nozzles respectively communicating therewith and to initiate formation of a drop in the liquid expelled from the nozzle communicating with each of said selected channels and further operating said electrically actuatable means to apply a second energy pulse to the liquid in each of said selected channels following said first energy pulse applied thereto to cause the liquid in which said drop formation is taking place to have a meniscus to which said drop being formed is attached which is convex is a direction in which said drop being formed is moving and is moving in a direction reverse to that in which said drop being formed is moving thereby to effect detachment of said drop, each of said second pulses being of lower energy content than said first energy pulses and of insufficient energy content itself to cause ejection of a drop of liquid from the corresponding nozzle.