Abstract: An ultrasonic cleaning apparatus comprising: a tank for in use receiving a cleaning liquid and an item to be cleaned; a plurality of transducers arranged, when driven, to direct ultrasonic pressure waves into the tank; and a controller arranged in use to drive the transducers. First and second transducers from the plurality of transducers are arranged in use to direct ultrasonic pressure waves into an overlapping volume; and the controller is arranged in use to drive the first and second transducers to produce ultrasonic pressure waves at different frequencies from each other. The controller is arranged to in use produce first and second drive signals for the transducers using first and second frequency generators to each switch between primary and secondary operation, with the sequential switching taking place to cause different combinations of primary and secondary operation for the first and second frequency generators to occur over time.

Abstract: An ultrasonic cleaning apparatus and method, the ultrasonic cleaning apparatus (10) comprising a tank (12) for in use receiving a cleaning liquid and for receiving an item to be cleaned in a cleaning region (16) thereof, a transducer (21) arranged, when driven, to direct ultrasonic pressure waves into cleaning liquid received in the tank (12) and a controller (30) arranged in use to drive the transducer (21), a gas introducer (40) arranged to in use provide a supply of gas into cleaning liquid in the tank so that macroscopic bubbles of gas are produced wherein the gas introducer (40) provides a plurality of bubble sources distributed below the cleaning region of the tank. The apparatus further comprises an assembly arranged in use to enable movement of the item to be cleaned in the cleaning region.

Abstract: An ultrasonic cleaning apparatus and method, the ultrasonic cleaning apparatus (10) comprising a tank (12) for in use receiving a cleaning liquid and for receiving an item to be cleaned in a cleaning region (16) thereof, a transducer (21) arranged, when driven, to direct ultrasonic pressure waves into cleaning liquid received in the tank (12) and a controller (30) arranged in use to drive the transducer (21), a gas introducer (40) arranged to in use provide a supply of gas into cleaning liquid in the tank so that macroscopic bubbles of gas are produced wherein the gas introducer (40) provides a plurality of bubble sources distributed below the cleaning region of the tank. The apparatus further comprises an assembly arranged in use to enable movement of the item to be cleaned in the cleaning region.

Abstract: An ultrasonic cleaning apparatus comprising: a tank for in use receiving a cleaning liquid and an item to be cleaned; a plurality of transducers arranged, when driven, to direct ultrasonic pressure waves into the tank; and a controller arranged in use to drive the transducers. First and second transducers from the plurality of transducers are arranged in use to direct ultrasonic pressure waves into an overlapping volume; and the controller is arranged in use to drive the first and second transducers to produce ultrasonic pressure waves at different frequencies from each other. The controller is arranged to in use produce first and second drive signals for the transducers using first and second frequency generators to each switch between primary and secondary operation, with the sequential switching taking place to cause different combinations of primary and secondary operation for the first and second frequency generators to occur over time.