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:
Jan. 15, 2002
Filed:
Jul. 21, 2000
Katsufumi Naka, Mie, JP;
Hitoshi Hasegawa, Mie, JP;
Kojin Co., Ltd., Mie, JP;
Abstract
An article surveillance security system with self-alarm operates at 6 through 10 MHz as a central frequency, receives a swept low level radio wave within ±5 through 15% from the central frequency, and sounds the alarm. It includes a tuning circuit ( ) tuning to the central frequency, and a differential amplifier ( ) for amplifying and detecting the output of the tuning circuit. The load resistance (R ) of the differential amplifier is set to 3 through 5 M&OHgr;, and the operating current of the differential amplifier is set to 3 &mgr;A or less. The base-emitter of the amplification/detection transistor (Tr ) of the differential amplifier are connected to the base-emitter of another diode-connected transistor (Tr ) to stabilize a bias drift by temperature. Thus, a receiving circuit of an article surveillance security system with self-alarm (tag) is realized with ability having a power supply of approximately four-year durability, stably operating with a very low level radio wave at 8.2 MHz, and suppressing external noise, especially a malfunction at a frequency band of a mobile telephone.