Inductive anti-theft alarm working by detection of resonant circuits

Abstract

Abstract Translated from French DISPOSITIF DE PROTECTION CONTRE LE VOL, DETECTANT LE PASSAGE D'UNE SELF PAR MODIFICATION DES LIGNES DE CHAMPS. L'INVENTION CONCERNE UN DISPOSITIF ELECTRONIQUE DE PROTECTION, DETECTANT LE PASSAGE NON AUTORISE D'ARTICLES DANS UN PASSAGE PROTEGE. IL EST CONSTITUE D'UN CADRE 1 EN ALUMINIUM SE PRESENTANT SOUS LA FORME D'UN HUIT. LA CARTE ELECTRONIQUE 2 GENERE DES COURANTS A FREQUENCES VARIABLES QUI SONT TRANSFORMES PAR LE CADRE 1 EN CHAMPS ELECTROMAGNETIQUES A FREQUENCES VARIABLES. LA BOUCLE SUPERIEURE DU CADRE 1A EMET LES LIGNES DE CHAMPS ET LA BOUCLE INFERIEURE 1B REFERME CELLES-CI. LES LIGNES DE CHAMPS SE TROUVENT REPARTIES DE FACON EGALE DE CHAQUE COTE DES FACES DU CADRE 1. UN CABLE BLINDE 7 RELIE LE CADRE 1 AU COFFRET D'ALIMENTATION-DETECTION-COMMANDE-PUISSANCE 8, ASSURANT L'ALIMENTATION DE L'ENSEMBLE AINSI QUE LES COMMANDES D'ALARMES. LE CIRCUIT, MODIFIANT LES LIGNES DE CHAMPS ET PERMETTANT AINSI LA DETECTION DE CELUI-CI LORS DU PASSAGE DEVANT LE CADRE, EST CONSTITUE D'UNE SELF 16A COMPORTANT UN ENROULEMENT DE FIL EMAILLE 17 ACCORDE PAR UN CONDENSATEUR 18 A LA FREQUENCE DE RESONANCE DU CADRE 1. PROTECTION AGAINST THEFT, DETECTING THE PASSAGE OF A SELF BY MODIFICATION OF FIELD LINES. THE INVENTION RELATES TO AN ELECTRONIC PROTECTION DEVICE, DETECTING THE UNAUTHORIZED PASSAGE OF ARTICLES THROUGH A PROTECTED PASSAGE. IT IS CONSTITUTED OF AN ALUMINUM FRAME 1 IN THE SHAPE OF AN EIGHT. ELECTRONIC BOARD 2 GENERATES CURRENTS AT VARIABLE FREQUENCIES WHICH ARE TRANSFORMED BY FRAME 1 IN ELECTROMAGNETIC FIELDS WITH VARIABLE FREQUENCIES. THE UPPER LOOP OF FRAME 1A EMITS THE FIELD LINES AND THE LOWER LOOP 1B CLOSES THESE. THE FIELD LINES ARE DISTRIBUTED EQUALLY ON EACH SIDE OF THE FRAME SIDES 1. A SHIELDED CABLE 7 CONNECTS FRAME 1 TO THE POWER SUPPLY-DETECTION-COMMAND-POWER BOX 8, ENSURING THE POWER SUPPLY OF THE ASSEMBLY AS WELL AS ALARM COMMANDS. THE CIRCUIT, MODIFYING THE LINES OF FIELDS AND THUS ALLOWING THE DETECTION OF THE FIELD WHEN PASSING IN FRONT OF THE FRAME, IS CONSISTING OF A SELF 16A INCLUDING A WINDING OF ENAMELLED WIRE 17 GRANTED BY A CAPACITOR 18 AT THE RESONANCE FREQUENCY OF THE FRAME 1.

Inventors

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