Device for outputting and/or receiving ultrasound and ultrasound sensor for inspecting a valuable document

An ultrasonic sensor for checking a value document in a detection area of the ultrasonic sensor by means of ultrasound at least of a predetermined frequency, comprising:

• an ultrasonic converter acting as a transmitter for the ultrasound and
• an ultrasonic converter acting as a receiver for the ultrasound, and at least one holder for the ultrasonic converters, wherein the at least one holder limits the detection area at least partly, and at least one portion, limiting the detection area, of the at least one holder has in the surroundings of the ultrasonic converter disposed in or on the holder a non-fibrous surface layer whose impedance is smaller than that of an inside layer of the holder adjacent to the surface layer.

An ultrasonic sensor for checking a value document in a detection area of the ultrasonic sensor by means of ultrasound of a predetermined frequency, comprising:

• an ultrasonic converter acting as a transmitter for the ultrasound and an ultrasonic converter acting as a receiver for the ultrasound;
• a holder portion in each case for the transmitter and the receiver which have ultrasonic channels flush with each other in each case in which the transmitter and receiver are so disposed in completely countersunk fashion as to form an ultra-sound path extending through the detection area, and
• wherein the ultrasonic converters are disposed so as to be inclined relative to an axis of alignment of the ultrasonic channels.