Abstract: An automatically controlled cleaning device (14) for removing visibility-impairing foreign matter, e.g. rain, snow or mud, from the surface of a window such as a motor vehicle windscreen (8). The device uses a sensor such as an ultrasonic transducer (12a, 12b) in which the frequency (f) and the spacing (d) between the transmitter (12a) and the receiver (12b) enable the presence of foreign matter to be detected simply by measuring the phase difference between the transmitted signal and the received signal. This device may be used in automatic wiper systems or the like.

Abstract: An automatically controlled cleaning device is adapted to remove foreign bodies such as water from the surface of a window, such as a car window, which has an inside surface and an outside surface. This device has cleaning element which define at least one predetermined area on the outside surface of this window, driving circuit for the cleaning element which operate in response to a control signal, detection element capable of supplying a detection signal representative of the presence of foreign bodies on the outside surface of the window and control device capable of supplying a control signal in response to the detection signal wherein the detection element comprise a transducer able to emit at least one incident ultrasonic signal propagating within the thickness of the window and able to receive a reflected ultrasonic signal representative of the presence of the foreign bodies to analyse the detection signal and where the transducer is fixed by a first face against the inside surface of the window.