Ultrasound detection device in particular for an automatically controlled windscreen cleaning system

An ultrasonic detection device arranged to detect a presence of foreign bodies on a window, comprising:

• a transducer for emitting a sequence of ultrasonic pulses which propagate through the thickness of said window and for receiving a series of reflected pulses resulting from each of said ultrasonic pulses, said transducer producing an echo signal representative of each of said series of reflected pulses;
• an integrator for integrating each of said echo signals within a time window so as to produce an integral value;
• a time delay circuit for controlling the instance of opening T1 and/or of closing T2 said time window, and
• a control circuit arranged, on the one hand, to determine an average value of a number of n integrated values and, on the other hand, to load a value of said instance of opening T1 and/or of closing T2 into said time delay circuit so as to maintain said average value at a steady value, wherein said control circuit is arranged to determine said average value by initially loading a first value of T1 and/or of T2 in said time delay circuit before the integration of a first x of echo signals, and secondly loading a second value of T1 and/or of T2 in said time delay circuit before the integration of a second n-x of said echo signals.