Patent ID: 8058771

Claim:
A method for driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising: generating a first ultrasonic drive signal by a generator coupled to an ultrasonic drive system, wherein the ultrasonic drive system comprises an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide, and wherein the ultrasonic drive system is configured to resonate at a resonant frequency; actuating the ultrasonic transducer with the first ultrasonic drive signal for a first period; generating a second ultrasonic drive signal by the generator; and actuating 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; generating a third ultrasonic drive signal by the generator; and actuating the ultrasonic transducer with the third ultrasonic drive signal for a third period; wherein the third drive signal is different from the first and second drive signals over the first, second, and third periods; and wherein the first, second, and third drive signals define a step function waveform over the first, second, and third periods.