Abstract:
An electronic circuit, apparatus and method for detecting and deactivating electronic article surveillance (“EAS”) tags, in which a coil induces a current when subject to an electromagnetic field and also is used to transmit an electromagnetic tag signal. A tuning capacitor is in electrical communication with the coil. The tuning capacitor and the coil establish a resonance for the transmission of the electromagnetic tag signal. A storage capacitor is in electrical communication with the coil. The storage capacitor receives the induced current from the coil. The electronic circuit, apparatus and method can also include a first diode for rectifying the induced current from the coil and a processor for determining an EAS tag status.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    n/a 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    n/a 
       FIELD OF THE INVENTION 
       [0003]    The present invention relates to electronic article surveillance (“EAS”) systems, and more particularly to a tag deactivator for an EAS system. 
       BACKGROUND OF THE INVENTION 
       [0004]    EAS systems are designed to prevent unauthorized removal of an item from a controlled area. In a typical EAS system, tags designed to interact with an electromagnetic field located at the exits of the controlled area are attached to articles to be protected. If a tag is brought into the electromagnetic field or “interrogation zone”, the presence of the tag is detected and appropriate action is taken. For a controlled area such as retail store, the appropriate action taken for detection of an EAS tag may be the generation of an alarm. Some types of EAS tags remain attached to the articles to be protected, but are deactivated prior to authorized removal from the controlled area by a deactivation device that changes a characteristic of the tag so that the tag is no longer detectable in the interrogation zone. 
         [0005]    The majority of EAS tag deactivation devices are fixed at a specific location, such as adjacent a point-of-sale (“POS”) station in a retail environment. If an article is purchased, and for whatever reason the attached EAS tag is not deactivated at the deactivator adjacent the POS station, the EAS tag will set off an alarm at the store exit. To then deactivate the EAS tag, the article must be brought back to the deactivator adjacent the POS station, which causes confusion and customer embarrassment. Handheld deactivators for EAS tags, sometimes known as “boot deactivators” that are part of a handheld bar-code scanner are known, but consist of only a passive demagnetizing magnet of alternating polarity. These devices provide no feedback to the user of the presence of an active tag or if the deactivation attempt was successful. Full function proximity handheld deactivators are superior in deactivation, but at the expense of added weight, manufacturing and purchase price and complexity. 
         [0006]    Typical handheld bar-code scanners having boot deactivators are passive devices and must either touch or be in very close proximity to deactivate the EAS tags. As the use of source tagging, which is the application of EAS security tags at the source, e.g., the manufacturer of the article, grows, the EAS tags will be located somewhere on an item or in its packaging. Since the user cannot see the tag when the tag is hidden somewhere on an item or in its packaging, the user may be unable to determine if all EAS tags associated with the article have been deactivated. Thus, another limitation of current boot deactivators is that a user receives no feedback from the boot deactivator as to whether an EAS tag has been deactivated or if it remains active. Often times, the user will “rub” a product or its packaging multiple times with a handheld deactivator in hope of deactivating all associated EAS tags. At other times, the user will be forced to pick up a heavy or large-sized box and use a high-powered table top deactivator for deactivation. This takes time and extra effort at the point of sale. Consequently, there is a need for an improved EAS deactivating device, such as a boot deactivator with user observable feedback, to indicate when EAS tags are deactivated. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention advantageously provides a circuit, apparatus and method for electronic article surveillance (“EAS”) tag detection, deactivation and EAS tag activation status indication. 
         [0008]    In accordance with one aspect, the present invention provides an electronic circuit for an electronic article surveillance (“EAS”) device. The electronic circuit includes a coil that induces a current when subject to an electromagnetic field. The coil is also used to transmit an electromagnetic tag signal. A tuning capacitor is in electrical communication with the coil. The tuning capacitor and the coil establish a resonance for the transmission of the electromagnetic tag signal. A storage capacitor is in electrical communication with the coil. The storage capacitor receives the induced current from the coil for the subsequent supply of power to the electronics. 
         [0009]    In accordance with another aspect, the present invention provides an apparatus for detecting and deactivating EAS tags. The apparatus includes a housing affixable to at least one of a bar code scanner and a radio frequency identification (“RFID”) scanner/reader. An electronic circuit is located within the housing. At least one user observable indicator is controlled by the electronic circuit. The user observable indicator is affixed to the housing and provides a tag deactivation status. Exemplary indicators can be visual, such as an LED, and/or audible, such as a piezo device or a speaker. 
         [0010]    In accordance with still another aspect, the present invention provides a method for generating deactivation status of electronic article surveillance (“EAS”) tags, in which a storage device of an electronic circuit is inductively charged. Communication is established with at least one EAS tag while operating the electronic circuit using the power stored in the storage device. The inductive charging of the storage device is disabled while communicating with the at EAS tag. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    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: 
           [0012]      FIG. 1  is a diagram of an EAS system for scanning a bar code of an item and deactivating an EAS tag constructed in accordance with the principles of the present invention; 
           [0013]      FIG. 2  is a prospective view of a boot deactivator for use with the EAS system of  FIG. 1  and constructed in accordance with the principles of the present invention; 
           [0014]      FIG. 3  is a schematic diagram of an exemplary electronic circuit of the boot deactivator and constructed in accordance with the principles of the present invention; 
           [0015]      FIG. 4  is a flowchart illustrating an exemplary logic process for the electronic circuit shown in  FIG. 3  in accordance with the principles of the present invention; and 
           [0016]      FIG. 5  is a flow chart of an exemplary tag detection and deactivation process in accordance with the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to the drawing figures in which like reference designators refer to like elements, there is shown in  FIG. 1  a diagram of an exemplary system constructed in accordance with the principles of the present invention and designated generally as “ 100 ”. Electronic article surveillance (“EAS”) system  100  includes a monitoring system that creates a system detection zone also know as an “interrogation zone” at an access point for a controlled area (not shown). Upon entering the interrogation zone, an active EAS tag creates a disturbance in the zone, which is detected by the receiver of an EAS system  100 . EAS systems, such as EAS system  100 , range from very low magnetic frequencies through the radio frequency range. These different frequencies play a role in establishing the features that affect operation. The EAS system  100  includes a handheld barcode scanner  102  and a boot deactivator  104 . In this embodiment, the boot deactivator  104  is attached near the tip portion  106  of barcode scanner  102 , which is illustrated as a gun type scanner. Of course, placement of the boot deactivator  104  is not limited to the tip  106  of gun type barcode scanner  102 , but can also be mounted at various locations, e.g., along the end of the handle portion of the gun type barcode scanner  102 . 
         [0018]    Moreover, the boot deactivator  104  is not limited to a gun type scanner but can be attached to other EAS handheld deactivators and devices such as tag detachers or RFID scanners (also known as RFID readers). The EAS system  100  further includes one or more security labels or EAS tags  108  located somewhere on an item  110  or in its packaging. EAS tag  108  can be a source tag which is not necessarily located on an outside surface of item  110 . The EAS system  100  can further include a charging pad (not shown) for recharging a power source of the barcode scanner  102  and/or the boot deactivator  104 . For example, the charging pad can be located with a table top price scanner at a POS checkout station. 
         [0019]    In operation, the boot deactivator  104  can concurrently deactivate the EAS tag  108  when the scanner  102  scans item  110  for checkout. For example, the boot deactivator  104  can deactivate EAS tags  108  when the tip  106  of the scanner  102  is pressed against or in close proximity to the label  108 . Since the boot deactivator  104  is attached to a portable handheld scanner  102 , deactivation of labels or EAS tags on large, bulky or heavy merchandise is made easier. For example, in situations where merchandise such as a large wide-screen television set located within a large box and/or several boxes of drinking water located on a shopping cart are too heavy or too bulky for a clerk to place on a table deactivator. In this example, a handheld scanner  102  with a boot deactivator  104  provides the convenience of deactivating tags  108  located inside or on the surface of these boxes without requiring a clerk to lift the boxes and place them on a table top deactivator to deactivate the tags  108 . 
         [0020]      FIG. 2  illustrates in more detail the handheld boot deactivator  104  of  FIG. 1 . In this embodiment, the boot deactivator  104  includes an outer housing  202 , which defines an aperture  204  and an electronic compartment  206 . The outer housing  202  of boot deactivator  104  can be made of any suitable material including plastic or metal. The electronic compartment  206  of the housing  202  provides an area to locate an electronic circuit  300  ( FIG. 3 ) for EAS tag detection, EAS tag deactivation and EAS tag deactivation status generation. The electronic compartment  206  can be an integrated part of the housing  202 , a recessed area within the housing  202  or a separate protective structure arranged to mate with the housing  202 . The electronic circuit  300  can be integrated into the electronic compartment  206  as shown in  FIG. 2  or the electronic circuit  300  can be a standalone device and separate from the electronic compartment  206 . The aperture  204  provides an unobstructed scan window for the scanner  102  ( FIG. 1 ). Accordingly, when the scanner  102  generates a scanning beam, e.g., a laser beam, for scanning a barcode of an item  110 , the beam is not blocked or obscured by the boot deactivator  104 . 
         [0021]    The boot deactivator  104  further includes one or more deactivation status indicators  208 ,  210 . In this embodiment, indicator  208  is a visual indicator, such as a light emitting diode (“LED”) and/or indicator  210  is an audio indicator, such as a speaker that generates an acoustic signal, tone or audible sound. For example, a green LED  208  on the boot deactivator  104  alerts users when an active EAS tag  108  is detected, while a speaker  210  may generates a tone, e.g., a “beep” to indicate that deactivation of the tag  108  has been attempted. Silence and/or no LED illumination after such a tone implies that the EAS tag  108  was successfully deactivated. It is contemplated that the status indicators  208  and  210  can be any of type of indication method including a vibrator, a LED, a speaker, etc. The deactivation status indicators can be user observable indicators that can be integrated or fixed to the housing  202 , in a recessed area within the housing  202  or in a separate protective structure arranged to mate with the housing  202 . 
         [0022]    Referring to  FIG. 3  is a schematic diagram illustrating an exemplary electronic circuit  300  for an EAS system that can be used with the boot deactivator  104  ( FIG. 2 ). Electronic circuit  300  can be located in electronic compartment  206  ( FIG. 2 ) and integrated into the boot deactivator  104  to perform EAS tag deactivation and EAS tag deactivation status indication. Electronic circuit  300  and electronic compartment  206  are sufficiently small in size so that electronic circuit  300  is easily integrated into the boot deactivator  104 . 
         [0023]    The exemplary electronic circuit  300  includes a magnet  302  coupled to charging/transceiving coil  304 . When magnet  302  and charging/transceiver coil  304  are placed in an electromagnetic field of a charging pad or table top deactivator, an alternating current (“AC”) is induced in the charging/transceiver coil  304 . The induced AC current is rectified by a diode  306 , such as a silicon controlled rectifier (“SCR”) diode that automatically commutates the AC current to produce a unidirectional current, i.e., direct current (“DC”), for charging a storage super-capacitor  308  and/or a small optional battery  310 . In this embodiment, SCR diode  306  can be a 4-layer solid state device that is used to produce variable DC voltages from AC line voltage and is used for power switching, phase control, battery charging, and inverter circuits. In addition, the SCR diode  306  is used to maintain a constant output current or voltage for the electronic circuit  300 . In this embodiment, a storage capacitor  308 , such as a super-capacitor, and/or an optional battery  310  are connected in parallel to each other and either one can selectively serve as a power source for electronic circuit  300 . As previously mentioned, battery  310  is optional since one embodiment of the electronic circuit  300  uses an inductive charging method to charge its power source. 
         [0024]    Electronic circuit  300  uses the capacitor  308  and/or the battery  130  as a bus voltage source V, e.g., 5V, which is divided and regulated through a voltage divider  312 . The voltage divider  312  includes a zener diode  314  connected in series with a resistor  316  and operates to provide the processor voltage, e.g., 3.3V across the zener diode  314 . In general, the zener diode  314  permits current to flow not only in a forward direction, similar to conventional diodes, but also in a reverse direction when the voltage is larger than the rated breakdown voltage also known as “zener voltage.” The zener diode  314  has a greatly reduced breakdown voltage and regulates the voltage across the electronic circuit  300 . An optional linear regulator  318  can be used regulate and/or to reduce or drop down the bus voltage across the zener diode supply voltage to a voltage range suitable for powering a digital signal processor (“DSP”)  320 , e.g., 1.8 V to 3.3V. 
         [0025]    DSP  320  provides for control and processing of signals to and from electronic circuit  300 . In one embodiment, DSP  320  “wakes up” periodically from a low power mode and transmits a current through the charging/transceiver coil  304  via a transmitter driver  322  and a resonant capacitor  324  (the capacitor  324  and coil  304  form a resonant circuit) to generate a pulse interrogation signal for transmission to tag  108 . In this embodiment, the transmitted pulse can be at an acousto-magnetic frequency of 58 kHz with less than 1.5 ms pulse width burst at a 36/30 Hz repetition rate (for 60/50 Hz local AC line frequency, respectively), so chosen to minimize interference with existing 60/50 Hz EAS systems. As briefly mentioned before, when acousto-magnetic systems transmit a magnetic frequency signal at 58 kHz in a pulsed pattern, the transmit signal energizes an acousto-magnetic tag in the detection zone. Upon completion of the transmit signal pulse, tag  108  responds by emitting a distinctive frequency signal. The tag signal can be at the same frequency e.g. 58 kHz, as the transmitted signal. During the period of time between pulses when the transmitter driver  322  is off, the receiver  326  can receive or detect the response signal transmitted by tag  108 . The receiver  326  amplifies and filters the response signal of tag  108 . The receiver  326  further passes the response signal of the tag  108  into an analog-to-digital (“A/D”) converter of the DSP  320 . 
         [0026]    The DSP  320  digitally filters the response signal received from the tag  108  and analyzes the spectrum of the response signal to obtain a profile of the tag  108 . The DSP  320  also checks the response signal from the tag  108  to ensure it has the proper tag signature, e.g., the proper frequency with corresponding defined characteristics for synchronization to the transmitter, at the proper level of amplitude, and at the correct repetition rate. When these criteria are present for successive measurements, there is a strong probability that the tag  108  has been detected. This unique tag signature enables the acousto-magnetic technology driven electronic circuit  300  of the present invention to deliver wide surveillance coverage, a high tag detection rate, and relative immunity to false alarms. When the tag  108  is detected, the DSP  320  will trigger an indicator to alert a user by either lighting the LED  328  or sending a pulse to an acoustic transducer  330  such as a piezo-composite transducer or speaker. The LED  328  or the speaker  330  can be connected to the DSP  320  directly. 
         [0027]    During the transmit mode, the SCR  306  prevents transmitted current from flowing into super-capacitor  308 . During those periods when the electronic circuit  300  does not receive a response from a tag, the electronic circuit  300  is ready for charging its power supply. Because a charging/transceiver coil  304  and a tuning capacitor (or resonant circuit component)  324  are used for both electromagnetic signal transmission and inductive charging, the electronic circuit  300  can be charged by a table top deactivator operating at approximately 58 kHz, or by a charging pad operating at a frequency a few kHz above or below 58 kHz. In general, this frequency range does not interfere with the EAS system frequency, but is still suitable for charging the capacitor  308 . 
         [0028]    In operation, the electronic circuit  300  will activate temporarily, search for an EAS tag, and provide a status signal to a user. Using the energy produced from a standard acousto-magnetic table top deactivator and/or charging pad, the electronic circuit  300  can be self-powered and thus not require a battery or a battery replacement, which allows the electronic circuit  300  to be a completely environmentally sealed unit. Acousto-magnetic systems typically transmit magnetic frequency signals at 58 kHz in a pulsed pattern. The transmit signal energizes an acousto-magnetic EAS tag in the detection zone. When the transmit signal pulse ends, the EAS tag responds, emitting a single very distinctive frequency signal. The EAS tag signal is typically at the same frequency as the transmitter signal but may vary according to design requirements. Charging of the battery is performed with inductive coupling from the acousto-magnetic table top deactivator and/or a charging pad. 
         [0029]    In operation, when the boot deactivator  104  receives a response from an EAS tag  108 , the electronic circuit  300  located in the electronic compartment  206  detects whether the EAS tag  108  is deactivated and presents a deactivation status indicator for the EAS tag  108  using any type of indication method. For instance, the boot deactivator  104  can also include at least one indicator integrated into boot deactivator  104  for indicating a deactivation status of an EAS tag  108 . Although  FIG. 2  shows the electronic compartment  206  embedded in the bottom of the boot deactivator  104 , this is for illustrational purpose as electronic compartment  206  can be integrated into the boot deactivator  104  in any configuration without departing from the scope and spirit of the invention. 
         [0030]    The method of charging the electronic circuit  300  by use of a table top deactivator or a charging pad&#39;s field energy to inductively charge the super-capacitor  308  and/or to power the electronic circuit  300 , can also be extended to other point of sale (“POS”) equipment such as a hard tag detacher, an EAS double checker, a barcode scanner, etc. An example of a known 58 kHz transmitting charger pad is a table top deactivator that continuously transmits a detection signal that can be used to charge the electronic circuit  300 . In one embodiment, a small battery can be added to the boot deactivator  104  to increase detection range and improve device performance consistency. In another embodiment, the method of charging the electronic circuit  300  uses the relative motion of the magnet  302  of the boot deactivator  104  and the charging/transceiver coil  304  to generate the recharge. For example, the magnet  302  coupled to the boot deactivator  104  can be mounted so that it moves in a relatively small area with respect to the charging/transceiver coil  304  when a user shakes the boot deactivator  104 . When this shaking occurs, a charge is generated by inductive coupling the charging/transceiver coil  304  and the acousto-magnetic magnet  302  thereby inductively charging the super-capacitor  308 . Additionally, low power storage, i.e., low charge on the capacitor  308  or the optional battery  310  can be detected by the electronic circuit  300  to trigger a low battery status indicator such as a distinctive pattern LED flash or audible alarm that is different from the tag deactivation indicators. 
         [0031]      FIG. 4  is a flow chart illustrating an exemplary operation  400  of the electronic circuit  300  for detecting and deactivating an EAS tag and for generating tag deactivation status indicators. At step S 402 , an induced AC current is generated by inductive charging. At step S 404 , the induced AC current is rectified by the diode  306 . Next at step S 406 , the rectified AC current can charge the storage super-capacitor  308 . A bus voltage is developed at step S 408 . At step S 410 , linear regulator  312  supplies voltage to power the DSP  320 . The optional linear regulator  312  drops the supply voltage as well as prevents the transmitted current from flowing back into the super-capacitor  308 . At step S 412 , the DSP  320  “wakes up” periodically from a low power mode to process transmitted and received signals from/to EAS tags. At step S 414 , the DSP  320  sends a current through the transmit/receive coil via transmitter driver  322  (step S 414 ) and resonant circuit including resonant capacitor  324  (step S 416 ) to generate an interrogation signal for transmission to an EAS tag  108 . At step S 418 , if the targeted tag  108  does not respond to the interrogation signal of electronic circuit  300  or if the electronic circuit is not detecting the EAS tag  108 , the process can return to step S 402 . Otherwise, if there is a response from the EAS tag  108 , a receiver circuit receives the response signal at step S 420  and passes the response signal to the DSP  320  for processing of the response and any associated tag data contained in the response. Prior to passing the tag response signal to the DSP  320  for processing, a receiver circuit  328  amplifies and filters the tag response signal (step S 420 ). Again, the DSP  320  processes the tag response signal to determine whether the tag response signal is valid and ready for deactivation, and if so transmits a deactivation signal to the tag  108  (step S 422 ). When the tag response signal is valid, the circuit  300  generates the tag status indication using any indicator type, such as a visual indication, e.g., green LED, or an audible tone, such as a “beep” discussed above (step S 424 ). The tag interrogation signal and the tag deactivation signal transmitted to the tag  108  via the coil  304  are referred to collectively herein as electromagnetic tag signals. 
         [0032]      FIG. 5  is a flow chart  500  illustrating an exemplary method for deactivating the EAS tag  108 . At step S 502 , an electronic circuit  300  for EAS tag deactivation and EAS tag detection status indication is activated upon an occurrence of a predetermined event. Once activation of the electronic circuit  300  is complete, the electronic circuit  300  searches for an EAS tag  108  by generating an interrogation signal (step S 504 ). Upon receiving a correctly transmitted interrogation frequency, the tag  108  resonates and can be detected. A typical interrogation frequency for acousto-magnet tags is about 58 kHz, which will be used herein as an example. At step S 506 , the electronic circuit  300  receives the resonated response with associated tag data from the EAS tag  108 . At step S 508 , the electronic circuit  300  processes the response signal with associated tag data to determine if the response signal is a valid EAS tag signal by examining the associated tag data for various attributes. For example, the response signal must have the proper spectral content and must be received in successive windows as expected. If the DSP  320  determines that the response signal is a valid EAS tag signal, then the DSP  320  may initiate deactivation, or indicate the detection of an EAS tag, depending on the particular mode of operation. At step S 508 , the when an EAS tag is detected, the electronic circuit  300  of boot deactivator  104  indicates the detected status of EAS tag  108  by activating the EAS tag status indicator, such as the illumination of LED  328  or the generation of an audio tone by speaker  330  (step S 510 ). During the time periods when electronic circuit  300  does not transmit or receive signals to/from tag  108 , electronic circuit  300  can be charged or recharged via the storage super-capacitor  308  or optional battery  310  (step S 512 ). Of note, although charging/recharging is shown as step S 512 , it is understood that charging can occur at any idle point in the tag detection cycle. 
         [0033]    The present invention advantageously provides and defines a portable circuit, apparatus and method for detecting tags attached to items in electronic article surveillance systems, deactivating the detected tags and generating a tag status indication. 
         [0034]    The embodiments of the invention can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. 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.