Patent ID: 8253303

Claim:
An apparatus for driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising: a generator configured to couple to an ultrasonic drive system of an ultrasonic instrument, the ultrasonic drive system comprising an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide; wherein the generator is configured to: generate a first ultrasonic drive signal; actuate the ultrasonic transducer with the first ultrasonic drive signal for a first period; generate a second ultrasonic drive signal by the generator; and actuate the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period; wherein the first drive signal is different from the second drive signal over the respective first and second periods; and wherein the first and second drive signals define a step function waveform over the first and second periods.