Patent ID: 7434919

Claim:
A jet break-off length measurement apparatus for a continuous liquid drop emission system comprising: a liquid drop emitter containing a positively pressurized liquid in flow communication with at least one nozzle for emitting a continuous stream of liquid; resistive heater apparatus adapted to transfer pulses of thermal energy to the liquid in flow communication with the at least one nozzle sufficient to cause the break-off of the at least one continuous stream of liquid into a stream of drops of predetermined volumes, and wherein said break-off occurs at a break-off length from the nozzle; sensing apparatus adapted to detect the stream of drops of predetermined volumes and generate a detected signal; control apparatus adapted to determine a characteristic of the stream of drops of predetermined volumes detected by the sensing apparatus and that is related to the break-off length from the nozzle, and a circuit that receives the detected signal and a reference signal derived from the pulses of thermal energy transferred to the liquid and generates an output that is dependent on at least the detected signal and the reference signal to the control apparatus.