Patent ID: 7486590
Filing Date: 2009-02-03
Classification: B06B,G01S,Y10S

Abstract:
1. A ultrasonic sensor with an adjustable detection range, namely, with an adjustable switching point curve, with an ultrasonic transducer for emitting and/or receiving ultrasonic waves in gaseous media, preferably air, whereby the sonic cone of the ultrasonic waves extends axially in the direction of the main axis of the main emitting direction and laterally in the direction perpendicular to said main axis, with a threshold value generator for generating at least one threshold value curve and with at least one comparator that has a first threshold value input ( 1 a ) to which the threshold voltage (U ref ) of the threshold value generator is applied as well as at least one signal input ( 1 b ) to which the transmit-receive signal (U signal ) of the ultrasonic transducer is applied, and when a transmit-receive signal (U signal ) that is greater than the threshold voltage (U ref ) is present at the comparator, the comparator emits a switching signal (S s ), wherein the change in the detection range or the change in the switching point curve of the ultrasonic sensor is made by influencing the threshold value curves that are generated by the threshold value generator, and the detection range can be adjusted either exclusively in the lateral extension of the sonic cone or else in the axial and lateral extensions of the sonic cone, whereby the exclusively lateral influencing of the detection range of the sonic cone is done by a time-dependent threshold generated in each case by the threshold value generator and this time-dependence of the threshold in the case of an exclusively lateral influence is defined in its entirety or in sections by a time-dependent function, said function decreasing either exponentially or linearly or else being a combination of both, or decreasing or increasing in sections or else alternately decreasing and increasing in sections while the detection range is simultaneously influenced axially and laterally by a time-independent threshold that can be adjusted with respect to the voltage value in each case, whereby the envelope curve generated from the ultrasonic sensor signal in each case is compared to the threshold voltage using the comparator, which then switches when the value of the envelope curve exceeds the threshold voltage.