Abstract: A system comprises a plate (235) and one or more transducers (200) coupled to the plate (235). Each of the one or more transducers (200) is operable to generate ultrasonic waves which propagate through the plate (235) in a propagation direction (240), for ultrasonically clearing droplets (250) of fluid from the plate (235). The plate (235) comprises one or more structures disposed in the path of ultrasonic waves and configured to control the propagation of ultrasonic waves in the plate (235) to achieve a predetermined amount of ultrasonic wave energy propagating in a direction opposite to the propagation direction (240). The value of one or more parameters of the shape of each of the one or more structures is predetermined to achieve a predetermined effect on ultrasonic waves incident on the structure.

Abstract: A system comprises a plate (235) and one or more transducers (200) coupled to the plate (235). Each of the one or more transducers (200) is operable to generate ultrasonic waves which propagate through the plate (235) in a propagation direction (240), for ultrasonically clearing droplets (250) of fluid from the plate (235). The plate (235) comprises one or more structures disposed in the path of ultrasonic waves and configured to control the propagation of ultrasonic waves in the plate (235) to achieve a predetermined amount of ultrasonic wave energy propagating in a direction opposite to the propagation direction (240). The value of one or more parameters of the shape of each of the one or more structures is predetermined to achieve a predetermined effect on ultrasonic waves incident on the structure.

Abstract: An apparatus for clearing water from a window comprises one or more transducers for coupling to a window. Each of the one or more transducers is operable at any selected one of a plurality of different frequencies to generate respective wave-types. A frequency generator (925) provides ultrasonic drive signals (926) to the one or more transducers for the plurality of different frequencies. A mode controller (930) controls the generator (925) and transducer configuration of electrodes (210) to apply to the window ultrasonic waves of any selected frequency and wave-type from the plurality of different frequencies and wave-types.

Abstract: A machine tool window is provided with an apparatus for ultrasonically clearing droplets of cutting fluid from the window. The apparatus comprises a one or more transducers (200, 210) coupled to the window. Each of the one or more transducers is operable to at any selected one of a plurality of different frequencies to generate respective wave-types. A frequency generator (925) is operable to provide ultrasonic drive signals (926) to the transducers for the plurality of different frequencies. A mode controller (930) controls the generator (925) and transducer (200) to apply to the window ultrasonic waves of any selected frequency and wave type from the plurality of different frequencies and wave-types.

Abstract: An apparatus for clearing water from a window comprises one or more transducers for coupling to a window. Each of the one or more transducers is operable at any selected one of a plurality of different frequencies to generate respective wave-types. A frequency generator (925) provides ultrasonic drive signals (926) to the one or more transducers for the plurality of different frequencies. A mode controller (930) controls the generator (925) and transducer configuration of electrodes (210) to apply to the window ultrasonic waves of any selected frequency and wave-type from the plurality of different frequencies and wave-types.

Abstract: A system for clearing precipitation from a window comprises one or more transducers (1-8) fixed to the window. The transducers are driven by a generator (13) to produce surface acoustic waves that propagate through the window. The window may be a laminated window such as a windscreen (10) for a vehicle. A sensing system (122) may be used for detecting the presence of precipitation to actuate the clearing system.