EP 0565481 B1 19970611 - Label detection apparatus
Title (en)
Label detection apparatus
Title (de)
Vorrichtung zur Detektion von Etiketten
Title (fr)
Dispositif de détection d'étiquettes
Publication
Application
Priority
CH 113292 A 19920407
Abstract (en)
[origin: EP0565481A1] The apparatus for detecting labels which are used for protecting goods against theft and are provided with an electrical resonant circuit (21) having a resonant frequency (fR) in the MHz range, comprises a transmitter (1) and a receiver (2). The transmitter (1) generates a transmitted signal sequence, the frequency of which is swept in sweep cycles over the predetermined resonant frequency of the labels and is radiated via a transmitting antenna (11). The signal is generated digitally and with corresponding phase angle with respect to each sweep cycle in the transmitter (1). In the receiver (2), the signals received by means of a receiving antenna (12) are sampled synchronously with the signal generation in the transmitter (1) and digitised. From the digitised signal values of n sweep cycles, a background is formed and subtracted from the digitised signal values of the last sweep cycle in each case. A long-time and a short-time background can also be formed and the latter can be subtracted from the former. Due to the background subtraction, in particular, interference which is relatively constant with respect to time can be discriminated such as is caused mainly by diffraction and reflections of the transmitted signal on objects existing in the environment of the transmitting and receiving antenna. <IMAGE>
IPC 1-7
IPC 8 full level
G08B 13/24 (2006.01)
CPC (source: EP US)
G08B 13/2414 (2013.01 - EP US); G08B 13/2471 (2013.01 - EP US); G08B 13/2488 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
US 5349339 A 19940920; AT E154459 T1 19970615; DE 59306713 D1 19970717; EP 0565481 A1 19931013; EP 0565481 B1 19970611; JP H06103472 A 19940415
DOCDB simple family (application)
US 1382593 A 19930203; AT 93810137 T 19930225; DE 59306713 T 19930225; EP 93810137 A 19930225; JP 4937693 A 19930310