Patent ID: 8266965

Claim:
Method for the contactless detection of laminated, flat objects, particularly sheet-like recording media, relative to separated single, multiple or missing sheets of recording media, the recording media intersecting a radiation path of at least one transmitter and an associated receiver of an ultrasonic sensor device and in which radiation transmitted by the recording media or radiation received in a case of a missing sheet by the receiver is received as a measuring signal, which is supplied to a following evaluation for generating a corresponding detection signal, at least the transmitting signal on the transmitter side is generated in a galvanically separated manner from the receiver by eliminating any voltage signal paths and any current signal paths between the transmitter and the receiver, and the transmitter and receiver are vibrationally decoupled from one another; wherein the transmitting signal undergoes at least one frequency modulation; and wherein at least one of tolerances and ageing effects of a transducer of the ultrasonic sensor device are corrected, more particularly automatically, by frequency modulation before and/or during operation.