Abstract:
A method and system for preventing simultaneous deactivation of multiple electronic article surveillance (“EAS”) tags. An RF pulse is transmitted within an EAS interrogation zone to induce a response from at least one EAS tag placed within the interrogation zone. The response of the at least one EAS tag is received. A presence of more than one EAS tag is determined by evaluating a frequency response curve corresponding to the response.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     n/a 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     n/a 
     FIELD OF THE INVENTION 
     The present invention relates generally to a method, system and electronic article surveillance (“EAS”) tag deactivator for deactivating “EAS” tags/labels, and more specifically to a method and system for detecting when multiple EAS tags/labels are being deactivated simultaneously. 
     BACKGROUND OF THE INVENTION 
     Shoplifting and other theft prevention has always been an important aspect for successful operation of any wholesale or retail sales facilities. Recent advances in automatic article identification technology provide these facilities with an improved means for detecting when an article is being shoplifted. One such method, Electronic Article Surveillance (“EAS”), typically includes an EAS detector and EAS devices commonly called labels, tags or transponders. The EAS detector transmits a radio-frequency (“RF”) carrier signal to any EAS device within a certain range of the detector. An active EAS device responds to the carrier signal by generating a response signal of a predetermined frequency, which triggers an alarm when received at the detector. For example, an active magneto-acoustic EAS tag resonates at a predetermined frequency when stimulated by an interrogation signal. When a customer purchases an item that is protected by an active EAS tag, a cashier typically deactivates the tag using deactivator that produces a magnetic deactivation field that alters the resonant frequency characteristic of the tag so that it no longer resonates at the predetermined frequency. The item may then be removed from the store without triggering an alarm. 
     A common method for shoplifting involves the collusion between a cashier and a customer known to the cashier to deactivate tags on items that have not actually been purchased. This method is referred to in the industry as “sweet-hearting.” Sweet-hearting takes place when a cashier scans or “rings up” one item and uses a deactivator to deactivate the EAS tag or label on more than one item. Generally, the cashier will physically “piggy-back” one item on top of another item so that a bar code scanner reading the universal product code (“UPC”) label will only detect the lower item, i.e., the item whose UPC label faces the bar code scanner. The cashier then passes the items over the deactivator, which deactivates both items simultaneously by transmitting an RF signal that both EAS tags receive. Often the item that is actually scanned and paid for is a low-cost item and the item that is simultaneously deactivated and not paid for is a high cost item. This shoplifting technique is difficult to visually detect because the cashier appears to be properly scanning and deactivating products. It is very difficult to determine that two items have been deactivated while only one has been purchased. 
     There are currently methods that prevent deactivation of EAS labels without scanning. These usually involve disabling the EAS deactivator until an item has been scanned. However, this method does not prevent sweet-hearting, it only prevents the occurrence of more than one deactivation process per scan. 
     Additionally, video monitoring may also used to try to detect sweet-hearting. The disadvantage of video methods is that they require surveillance personnel to manually review video tape to find evidence. Also, cashiers or service personnel that actually commit these sweet-hearting acts may be quite adept at concealing their actions from video surveillance, thus, even the most prudent observer may not detect the action. 
     Therefore, what is needed is a method to automatically detect the simultaneous deactivation of multiple EAS labels so that suspicious transactions may be identified. 
     SUMMARY OF THE INVENTION 
     The present invention advantageously provides a method, EAS tag deactivator and security system for preventing simultaneously deactivation of multiple electronic article surveillance (“EAS”) tags. Generally, the present invention provides a method for examining the frequency response of an EAS tag placed in an interrogation zone of the deactivator prior to deactivation. If the frequency response includes more than one peak, a video collection event is triggered to capture video footage of the deactivation. Alternatively, further EAS tag deactivation may be inhibited. 
     One aspect of the present invention provides a method for preventing simultaneous deactivation of multiple EAS tags. An RF pulse is transmitted within an EAS interrogation zone to induce a response from at least one EAS tag placed within the interrogation zone. The response of the at least one EAS tag is received. A presence of more than one EAS tag is determined by evaluating a frequency response curve corresponding to the response. 
     In accordance with another aspect, the present invention provides an electronic article surveillance (“EAS”) tag deactivator for deactivating at least one EAS tag. The EAS tag deactivator has a transceiver and a controller communicatively coupled to the transceiver. The transceiver is operable to transmit an RF pulse within an EAS interrogation zone to induce a response from the at least one EAS tag placed within the interrogation zone and to receive the response of the at least one EAS tag. The controller is operable to determine a presence of more than one EAS tag by evaluating a frequency response curve corresponding to the response. 
     In accordance with yet another aspect, the present invention provides a security system for preventing theft of merchandise. The security system includes a plurality of EAS tags and an EAS tag deactivator. The EAS tag deactivator is operable to transmit an RF pulse within an EAS interrogation zone to induce a response from at least one EAS tag placed within the interrogation zone. The EAS tag detector is further operable to receive the response of the at least one EAS tag, determine that the response contains more than one peak in a frequency response curve corresponding to the response, and evaluate the frequency response curve of the response to determine a presence of more than one EAS tag. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is an illustration of an electronic article surveillance (“EAS”) tag deactivation system constructed in accordance with the principles of the present invention; 
         FIG. 2  is a block diagram of the electronic article surveillance (“EAS”) tag deactivation system of  FIG. 1 , constructed in accordance with the principles of the present invention; 
         FIG. 3  is a block diagram of an EAS tag deactivator constructed in accordance with the principles of the present invention; 
         FIG. 4  is a flowchart of an exemplary multiple tag detection process according to the principles of the present invention; 
         FIG. 5  is a graph illustrating a frequency response distribution of an exemplary sampling of EAS tag responses; 
         FIG. 6  is a graph illustrating an exemplary frequency response of a single EAS tag response; 
         FIG. 7  is a graph illustrating an exemplary frequency response when two EAS tags are simultaneously detected in accordance with the principles of the present invention; and 
         FIG. 8  is a graph illustrating an exemplary frequency response of two EAS tags detected simultaneously and shifted by a DC bias field in accordance with the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before describing in detail exemplary embodiments that are in accordance with the present invention, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to implementing a system and method for automatically detecting the simultaneous deactivation of multiple EAS labels so that suspicious transactions may be identified. Accordingly, the system and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terms “EAS tag” and “EAS label” may be used interchangeably in reference to an electronic article surveillance device affixable to an item of merchandise and detectable by an EAS detector and/or EAS reader. Additionally, as used herein, the term “Zigbee” relates to a suite of high-level wireless communication protocols as defined by the Institute of Electrical and Electronics Engineers (“IEEE”) standard 802.15.4. Further, “Wi-Fi” refers to the communications standard defined by IEEE 802.11. The term “WiMAX” means the communication protocols defined under IEEE 802.16. “BLUETOOTH” refers to the industrial specification for wireless personal area network (“PAN”) communication developed by the Bluetooth Special Interest Group. 
     One embodiment of the present invention advantageously provides an EAS tag/label deactivator that has the ability to detect multiple labels within a deactivation zone by identifying more than one label response frequency. The deactivation zone may include or overlap an interrogation zone wherein the deactivator determines that only one EAS tag is present prior to magnetizing the deactivation zone. The deactivator performs a frequency discrimination method using fast-Fourier transforms (“FFT”) or alternate frequency measurement algorithms to measure the frequency of signals emanating from EAS tags/labels within the interrogation zone. When more than one EAS label is detected, the deactivator may be inhibited from further operation to prevent deactivation of more than one label at a time. 
     Another embodiment of the deactivator may be equipped with a communication capability to register multiple detection events in a database or to trigger recording by a video camera to capture the event for potential action by loss prevention authorities. 
     In an alternate embodiment of the invention, a DC bias field may be introduced into the detection field of the deactivator. Since multiple labels are presented to the deactivator in different locations and orientations, the DC bias field causes different levels of frequency shift in each of the labels present in the deactivator&#39;s detection field allowing the system to better discriminate the presence of multiple labels. 
     Referring now to the drawing figures in which like reference designators refer to like elements, there is shown in  FIGS. 1 and 2 , an exemplary electronic article surveillance (“EAS”) tag deactivation system  10  for automatically detecting the simultaneous deactivation of multiple EAS labels, constructed in accordance with the principles of the present invention. System  10  may include an EAS deactivator  12  for deactivating and/or removing EAS tags  14   a ,  14   b  (collectively referenced as EAS tag  14 ), a bar code scanner  16 , and a point of transaction (“POS”) terminal  18 , e.g., a cash register. The bar code scanner  16  scans Universal Product Code (“UPC”) labels affixed to or printed on items of merchandise to determine the identity of the item and report the items to the point of transaction terminal  18 . UPC bar code scanning is known in the art and is beyond the scope of the present invention. The barcode scanner  16  is currently shown as a separate device on the POS terminal  18 ; however, the barcode scanner  16  may also be mounted in the counter adjacent to the deactivator  12 . Additionally, many new deactivator products include the deactivator coil mounted inside the cover of the scanner (integrated scanner/deactivator). Both of these mounting options allow the cashier to scan and deactivate in a single motion, thereby improving the speed at which the transaction may be completed. The point of transaction terminal  18  records information concerning the sale of the item or other transaction. The point of transaction terminal  18  may be in communication with a data server  20  containing a database  22  of all transactions processed by the system  10 . 
     Additionally, the system  10  may include a video camera  24  for capturing surveillance video of actions occurring in the vicinity of the point of transaction terminal  18 . The video camera  24  may be communicatively coupled to a video recording system  26  for storing captured video images for later retrieval. The system  10  may also trigger an audible and/or visual alarm (not shown). 
     Referring now to  FIG. 3 , an exemplary EAS deactivator  12  includes a transceiver  28  communicatively coupled to a controller  30 . The transceiver  28  transmits RF signals to any EAS tags  14  within an applicable interrogation zone and receives a response signal at a primary frequency from the tags  14 . The controller  30  controls the processing of information and the operation of the EAS deactivator  12  in a well-known manner. The controller  30  is also coupled to a communication interface  32  which controls the transfer of information between the deactivator  12  and the point of transaction terminal  18 , the data server  20  and/or the video recording system  26 . The communication interface  32  may be wired, wireless, or any combination thereof. The communication interface  32  transfers data between the deactivator  12  and the point of transaction terminal  18 , the data server  20  and/or the video system  26  using known communication protocols such as, for example, Ethernet, Wi-Fi, WiMAX, Zigbee, Bluetooth, etc. Additionally, the communication interface  32  may transfer information between the deactivator  12  and the point of transaction terminal  18  using a proprietary communication protocol. 
     The controller  30  is also coupled to an input/output interface  34  and a non-volatile memory  36 . The input/output interface  34  controls the reception and presentation of information to and from a user through various well-known peripheral devices such as a display screen, a keyboard, a mouse, a printer, a web browser, etc. The controller  30  may also be coupled to a DC-biased electromagnetic field generator  38  which is used to generate a magnetic field to shift the frequency response of any EAS tag  14  located within the deactivation zone. 
     The non-volatile memory  36  includes a data memory  40  and a program memory  42 . Examples of non-volatile memory include, but are not limited to, a hard drive, a memory stick, an Electrically Erasable Programmable Read-Only Memory (“EEPROM”), a flash memory, etc. Additionally, instead of or in addition to non-volatile memory  36 , the data memory  40  may be included as some form of volatile memory, e.g., RAM. The program memory  42  contains an EAS tag detector  44  for detecting the presence of one or more EAS tags  14  within the deactivation zone and a frequency discriminator  46  for measuring the frequencies of detected signals. The operation of the EAS tag detector  44  and the frequency discriminator  46  are discussed in more detail below. 
     Referring now to  FIG. 4 , an exemplary operational flowchart is provided that describes steps performed by an EAS tag deactivator  12  for simultaneously detecting multiple EAS tags  14 . Of note, although the present invention is described with respect to the EAS tag deactivator  12  detecting and deactivating the EAS tags  14 , the present invention is not limited to such. It is contemplated that a device (not shown) that is separate from the tag deactivator  12  can be used to detect the presence of the EAS tags  14  and communicate with the EAS tag deactivator  12  to trigger a deactivation cycle. 
     The process begins when the EAS tag detector  44  detects the presence of at least one EAS tag  14  within the interrogation zone (step S 100 ). Generally, to detect an EAS tag  14 , the EAS tag deactivator  12  transmits an RF pulse within the interrogation zone which causes the EAS tag  14  resonate at its natural resonant frequency. A frequency response signal for an exemplary EAS tag  14  is shown in  FIG. 5 . In the embodiment illustrated in  FIG. 5 , the EAS tags  14  may generate a response signal centered around 58 kHz, with a bell curve distribution pattern of ±200 Hz, as shown in  FIG. 6 . As the natural response frequency of each tag may inherently be slightly different, if more than one EAS tag  14  is present, the resultant frequency response generated by the combined EAS tags  14  will have multiple peaks, as shown in  FIG. 7 . 
     The EAS tag detector  44  may optionally apply an intermittent DC bias current (step S 102 ) to produce an electromagnetic field within the deactivation zone to more readily detect the different response frequency peaks. The electromagnetic field shifts the response frequencies of the EAS tags  14  dependant upon such factors as the composition of the materials within the EAS tag  14 , the strength of the DC current, and the spatial positioning of the EAS tags  14 . Each tag  14  reacts slightly differently to the DC-biased field, causing different levels of frequency shift in each of the EAS tags  14  present in the EAS tag deactivator&#39;s  12  detection field. The differences in frequency shift are due primarily because the tags  14  are located in different locations and orientations relative to the EAS tag deactivator  12 . Thus, in the event that the EAS tags  14  undergoing deactivation happen to have response (peak) frequencies so close in value that the frequency discriminator  38  cannot discern more than one tag  14 , the applied DC-bias current changes the electromagnetic field enough that the frequency response peaks shift apart and allows the detection of multiple tags  14 , as shown in  FIG. 8 . By intermittently applying the bias current, the peak response frequencies of different EAS tags  14  are detected even if one response would normally be masked or hidden by the other response. 
     The frequency discriminator  46  may operate according to known techniques, such as using a Fast Fourier Transform (“FFT”) filter or alternative algorithm to detect multiple frequencies. The EAS tag detector  44  then uses the determined frequencies to calculate the separation between the frequencies (step S 104 ). If the separation between the detected frequencies is less than a predetermined value, e.g., 50 Hz (step S 106 ), then the EAS tag detector  44  concludes that only one EAS tag  14  is currently being deactivated and allows the EAS tag  14  to be deactivated as normal. Based on the Q factor of existing EAS labels, the present invention is able to discriminate frequencies with peaks separated by about 50 to 100 Hz. Therefore, the lower limit for detection should be set in this range. However, the separation distance may be decreased for situations where the user wishes to capture video of suspected sweet-hearting events. The separation distance may be increased if the user wishes to disable deactivation to prevent potential false alarms, which may cause an inconvenience to the customer. 
     However, if the separation between the frequencies exceeds the predetermined value (step S 106 ), then the EAS tag detector  44  may trigger the video recording system  26  to capture video images of the area surrounding the EAS deactivator  12  (step S 110 ) or flag video images already being recorded so that the incident may be further investigated. Additionally and/or alternately, the EAS tag detector  44  may log information relevant to the incident in the database  22  (step S 112 ) or data memory  40  so that the incident may be further investigated. The information may include a time and date of the incident, the name or other identifier of the cashier on duty at the time of the incident, the name or other identifier of a manager on duty at the time of the incident, an identifier for the point of transaction terminal, transaction-specific information, etc. The EAS tag detector  44  may also disable the EAS tag deactivator  12  from further use (step S 114 ) so that it does not operate to deactivate even the newly detected tags, requiring a manager or other authorized personnel to reset the EAS tag deactivator  12  before it can be used again. Additionally, the EAS tag detector  44  may further trigger an audible and/or a visual alarm. 
     The present invention advantageously provides a method to detect to sweet-hearting and to collect evidence of theft that may be used to build a case for future prosecution. The present invention can be realized in hardware, software, or a combination of hardware and software. Any kind of computing system, or other apparatus adapted for carrying out the methods described herein, is suited to perform the functions described herein. 
     A typical combination of hardware and software could be a specialized or general purpose computer system having one or more processing elements and a computer program stored on a storage medium that, when loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded in a computing system is able to carry out these methods. Storage medium refers to any volatile or non-volatile storage device. 
     Computer program or application in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduction in a different material form. 
     In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. Significantly, this invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and accordingly, reference should be had to the following claims, rather than to the foregoing specification, as indicating the scope of the invention. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.