The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 1992
Filed:
Aug. 14, 1990
Harm J Kip, Lichtenvoorde, NL;
Tallienco W Fockens, Eibergen, NL;
N.V. Nederlandsche Apparatenfabriek Nedap, De Groenlo, NL;
Abstract
An electromagnetic identfication system of the kind in which a transmitter generates an electromagnetic interrogation field in a detection zone. At least one passive responder is provided capable of disturbing the interrogation field. A detection circuit detects a disturbance of the interrogation field caused by a responder. The responder is a single receiver circuit which responds to the interrogation field which supplies energy to activate a digital encoding circuit having a binary-code defining circuit. The encoding circuit is arranged, in operation, through a switch to vary the electrical characteristics of the receiver circuit to generate a code signal that is detectable by the detection circuit. The encoding circuit is arranged to control the switch during the pre-determined periods of time for varying the electrical characteristics of the receiver circuit. A programmer is provided to modulate the transitter to generate a modulated interrogation field.