Electronic anti-shoplifting system employing an rfid tag

Abstract

An electronic anti-shoplifting system monitors articles of merchandise in a sales outlet to deter shoplifting. The system is provided with transponder tags connected to the articles of merchandise. A tag exciter is positioned at an exit leading from the sales outlet and generates an RF surveillance excitation signal. If a customer carries an article through the exit without removal authorization due to failure to pay for the article, the transponder tag is activated, being powered by the RF surveillance excitation signal as the customer passes the tag exciter. The activated transponder tag generates an RF surveillance response signal that triggers an alarm. If the customer has removal authorization as the result of paying for the article, the transponder tag is reprogrammed to modify the operational data stored therein. The operational data typically includes data to alter the frequency of an RF response signal generated by the transponder tag, the frequency of an RF excitation signal to which the transponder tag responds, and/or the type of modulation used by the transponder tag to generate an RF response signal. Sales data, such as the purchase price and date of purchase, is also stored in the transponder tag. When the customer exits the sales outlet after the transponder tag is reprogrammed, the transponder tag does not generate the RF surveillance response signal that triggers the alarm. However, the sales data stored in the transponder tag can be accessed by the clerk of the sales outlet at a later date.