US Patent 10401618 Ultrasonic lens cleaning system with current sensing

Disclosed examples include ultrasonic cleaning systems, driver integrated circuits and methods for cleaning a lens, in which an oscillating drive signal is provided to an ultrasonic transducer and the driver controls the frequency of the drive signal according to a current sense signal representing a drive current flowing in the transducer. The driver sweeps the drive signal frequency and compares the sensed current values with predetermined profiles corresponding to a clean lens and a lens with one or more known contaminants, and generates the drive signal at one or more frequencies corresponding to peaks or valleys of the sensed current values or predetermined frequencies to promote cleaning of the lens.