System and method for reducing cart alarms and increasing sensitivity in an EAS system with metal shielding detection

A system for detecting electronic article surveillance (“EAS”) marker shielding includes an EAS subsystem a metal detector, a cart detection subsystem and a processor. The EAS subsystem is operable to detect an EAS marker in an interrogation zone. The metal detector is operable to detect a metal object in the interrogation zone. The cart detection subsystem includes a sensor array. The cart detection subsystem is operable to differentiate between a wheeled device and a human passing through the interrogation zone based on the sensor array. The processor is electrically coupled to the EAS subsystem, the metal detector and the cart detection subsystem. The processor is programmed to receive information outputted from the cart detection system and information outputted from the metal detector to determine whether to generate an alarm signal based on the presence of EAS marker shielding.

CROSS-REFERENCE TO RELATED APPLICATION

FIELD OF THE INVENTION

The present invention relates generally to electronic article surveillance (“EAS”) systems and more specifically to a method and EAS system that detects metals and magnetic materials and reduces false alarms caused by the presence of a metallic cart in the EAS interrogation zone.

BACKGROUND OF THE INVENTION

Electronic article surveillance (“EAS”) systems are commonly used in retail stores and other settings to prevent the unauthorized removal of goods from a protected area. Typically, a detection system is configured at an exit from the protected area, which comprises one or more transmitters and antennas (“pedestals”) capable of generating an electromagnetic field across the exit, known as the “interrogation zone”. Articles to be protected are tagged with an EAS marker that, when active, generates an electromagnetic response signal when passed through this interrogation zone. An antenna and receiver in the same or another “pedestal” detects this response signal and generates an alarm.

Because of the nature of this process, other magnetic materials or metal, such as metal shopping carts, in proximity to the EAS marker or the transmitter may interfere with the optimal performance of the EAS system. Further, some unscrupulous individuals utilize EAS marker shielding, e.g., metal foil, with the intent of shoplifting merchandise without detection from any EAS system. The metal can shield tagged merchandise from the EAS detection system.

Current EAS systems implementing metal shielding detection mechanisms may sometimes be fooled by various cart configurations and overpowered by the response of a large mass of metal. Some systems attempt to overcome this problem by lowering the gain of the system, which limits the sensitivity and reduces the detection capability for small items, such as the metal shielding they are trying to detect.

Other conventional systems may include a “shopping cart inhibit” feature in the EAS system/metal detection configuration. By monitoring the overall mass of the metal response signal, a threshold can be implemented indicating an inhibit situation so that the system will not falsely generate an alarm. However, even with this solution implemented, some store merchandise will continue to fool the system and result in a false alarm or missed detection. For example, detection of large metal shielding positioned close to the pedestals is reduced because these shields produce readings which exceed the thresholds.

Therefore, what is needed is a system and method for independently detecting the presence of a cart or stroller within an EAS interrogation zone, thereby allowing increased sensitivity of an EAS system with metal shield detection capabilities.

SUMMARY OF THE INVENTION

The present invention advantageously provides a method and system for detecting electronic article surveillance (“EAS”) marker shielding by independently detecting the presence of a cart or other wheeled device with the EAS interrogation zone. Generally, the present invention is able to differentiate between a wheeled device and a human walking between the pedestals by examining a breakage pattern from a sensor array located on the pedestals just above the floor.

In accordance with one aspect of the present invention, a system for detecting EAS marker shielding includes an EAS subsystem, a metal detector, a cart detection subsystem and a processor. The EAS subsystem is operable to detect an EAS marker in an interrogation zone. The metal detector is operable to detect a metal object in the interrogation zone. The cart detection subsystem includes a sensor array. The cart detection subsystem is operable to differentiate between a wheeled device and a human passing through the interrogation zone based on the sensor array. The processor is electrically coupled to the EAS subsystem, the metal detector and the cart detection system. The processor is programmed to receive information outputted from the cart detection system and information outputted from the metal detector to determine whether to generate an alarm signal based on a presence of EAS marker shielding.

In accordance with another aspect of the present invention, a method is provided for detecting EAS marker shielding. A metallic object is detected within an interrogation zone. A wheeled device is differentiated from a human passing through the interrogation zone. Responsive to determining that a wheeled device is not passing through the interrogation zone, an alert signal is generated which notifies the presence of EAS marker shielding.

In accordance with yet another aspect of the present invention, an electronic EAS system controller for use with a metal detector includes an EAS subsystem, a communication interface, a cart detection subsystem and a processor. The EAS subsystem is operable to detect an EAS marker in an interrogation zone. The communication interface is operable to receive inputs from the metal detector. The cart detection subsystem includes a sensor array. The cart detection subsystem is operable to differentiate between a wheeled device and a human passing through the interrogation zone based on the sensor array. The processor is electrically coupled to the EAS subsystem, the communication interface and the cart detection subsystem. The processor is programmed to receive information outputted from the cart detection system and information outputted from the metal detector to determine whether to generate an alarm signal based on a presence of EAS marker shielding.

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 independently detecting the presence of a cart or stroller within an EAS interrogation zone, thereby allowing increased sensitivity of an EAS system having EAS marker shielding detection capabilities. 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.

One embodiment of the present invention advantageously provides a method and system for detecting a cart or stroller in an interrogation zone of an EAS system and improving the sensitivity of the EAS system to detect an EAS marker shield. The EAS system combines traditional EAS detection capabilities with a set of infrared sensor arrays located near the floor on the base of the EAS pedestals to detect the movement of a wheel passing through the interrogation zone.

Referring now to the drawing figures in which like reference designators refer to like elements, there is shown inFIG. 1one configuration of an exemplary EAS detection system10constructed in accordance with the principles of the present invention and located, for example, at a facility entrance. EAS detection system10includes a pair of pedestals12a,12b(collectively referenced as pedestal12) on opposite sides of an entrance14. One or more antennas for the EAS detection system10may be included in pedestals12aand12b, which are located a known distance apart. The antennas located in the pedestals12are electrically coupled to a control system16which controls the operation of the EAS detection system10. The system controller16is electrically connected to a metal detector18, a people counting system20and an infrared sensor array22for more accurately detecting the presence of a foil-lined bag. The infrared sensor array22consists of a pair of infrared sensor panels22a,22b(referenced collectively as “infrared sensor array22”). It is also contemplated that other types of sensor arrays can be used, such as a pressure sensitive mat arranged to provide data indicating where pressure has been applied, and the like.

The metal detector18may be a separate unit, communicatively connected to the system controller16, or may be integrated into the system controller16. One exemplary metal detector18is disclosed in U.S. patent application Ser. No. 12/492,309, filed Jun. 26, 2009 and entitled “Electronic Article Surveillance System with Metal Detection Capability and Method Therefore,” the entire teachings of which are hereby incorporated by reference.

The people counting system20may be a separate device, such as an overhead people counter, or may be physically located in one or more pedestals12and/or integrated into the system controller16. The people counting system may include, for example, one or more infrared sensors mounted approximately 8 to 14 feet (2.5 m to 4.3 m) above the retailer's entrance/exit. Integrating people counting sensors into the EAS detection pedestal12helps to ensure a simple and effective method of delivering essential operational information. In operation, the people counter detects the movement of a person into, through, or out of the predetermined area. That information is collected and processed by the people counting system20, e.g., using a programmed microprocessor. People counting data may then be transmitted using conventional networking means to other portions of the EAS detection system10, and/or through the store's internal network or across wide area networks such as the Internet, where it can be sorted, reported and studied.

Referring now toFIGS. 2 and 3, perspective views of a cart24transiting the exemplary EAS system10are provided. As can be seen fromFIG. 2, the infrared sensor arrays22are located at the base of the pedestals12at a height of about ¼ inch (6.4 mm) to 2 inches (51 mm) from the floor. The length of the infrared sensor array22should be at least 6-12 inches (152 mm-305 mm) long to allow for differentiation between a cart wheel and a human foot. The infrared sensor array22is arranged such that the sensors produce multiple parallel beams26between the pedestals12, as shown inFIG. 3. Because of the proximity of the beams to the floor, the beams26are broken by the wheels of a cart24, stroller or other wheeled-object passing between the pedestals12. The beams26are also broken when a person walks between the pedestals; however, the pattern of breakage for a person walking through the beams26is different than that of a cart24rolling through the beams26. For example, since the wheels of a cart24never leave the floor, the cart24will break the beams26sequentially and will always pass through each beam26, but a person walking may break several beams26simultaneously and does not necessarily break each beam26in the array22. By recognizing the differences in these patterns, an embodiment of the present invention is able to distinguish a cart24or stroller from other metallic objects and use this information to increase the sensitivity and accuracy of its metal foil-lined bag detection. The operation of the infrared sensor array22in combination with the system controller16is discussed in greater detail below.

Referring now toFIG. 4, an exemplary EAS system controller16may include a controller28(e.g., a processor or microprocessor), a power source30, a transceiver32, a memory34(which may include non-volatile memory, volatile memory, or a combination thereof), a communication interface36and an alarm38. The controller28controls radio communications, storage of data to memory34, communication of stored data to other devices, and activation of the alarm38. The power source30, such as a battery or AC power, supplies electricity to the EAS control system16. The alarm38may include software and hardware for providing a visual and/or audible alert in response to detecting an EAS marker and/or metal within an interrogation zone of the EAS system10.

The transceiver32may include a transmitter40electrically coupled to one or more transmitting antennas42and a receiver44electrically coupled to one or more receiving antennas46. Alternately, a single antenna or pair of antennas may be used as both the transmitting antenna42and the receiving antenna46. The transmitter40transmits a radio frequency signal using the transmit antenna42to “energize” an EAS marker within the interrogation zone of the EAS system10. The receiver44detects the response signal of the EAS marker using the receive antenna46. It is also contemplated that an exemplary system10could include a transmitting antenna42and receiver44in one pedestal, e.g., pedestal12aand a reflective material in the other pedestal, e.g., pedestal12b.

The memory34may include a metal detection module48for detecting the presence of metal within the interrogation zone and a cart detection module50for determining if the detected metal is a cart, stroller or other wheeled object, e.g., a wheel-chair, hand-truck, etc. Operation of the metal detection module48and the cart detection module50is described in greater detail below. The metal detection module48, in conjunction with the cart detection module50, may determine whether to trigger the alarm38by analyzing output information received from the metal detector18, the people counting system20and the infrared sensor arrays22via the communication interface36. For example, if the cart detection module50has detected the passage of a person through the interrogation zone and the metal detector18has just detected a source of metal that fits the characteristics of a metal shield, the metal detection module48may trigger the alarm38by sending an alarm signal via the controller28. The alarm38alerts store security or other authorized personnel who may monitor or approach the individual as warranted.

The controller28may also be electrically coupled to a real-time clock (“RTC”)52which monitors the passage of time. The RTC52may act as a timer to determine whether actuation of events, such as metal detection or person counting, occurs within a predetermined time frame. The RTC52may also be used to generate a time stamp such that the time of an alarm or event detection may be logged.

Referring now toFIG. 5, a flowchart is provided that describes exemplary steps performed by the EAS system10to determine whether an object passing through the pedestals12is a cart24or other wheeled-device. The system controller16enables the infrared sensor arrays22by activating a beam sequence which is dependent upon the configuration of the infrared sensor array22(step S102).

The infrared sensor array22may be configured in a variety of manners. For example, as shown inFIG. 6, the infrared sensor array22may have one sensor panel22athat includes only transmit components54a-54j(referenced collectively as “transmit component54”) and the second sensor panel22bincludes only receive components56a-56j(referenced collectively as “receive component56”). It should be noted that, althoughFIG. 6shows10pairs of infrared sensors, the number of sensor pairs shown is for illustrative purposes only and any number of sensor pairs that reliably produce a recognizable breakage pattern may be selected for implementation. For example, the present invention has been found to perform satisfactorily using five pairs of sensors. Also, although any sensor spacing can be used as long as the spacing allows determination of wheeled cart vs. human as described herein, one embodiment of the present invention implements the sensors approximately 2.75 to 3.00 inches (69.9 mm to 76.0 mm) apart.

While sensors having focused elements are preferred, the present invention can be implemented using non-focused elements. Also, while automatic gain control (“AGC”) circuitry can be used as part of the sensor circuit, the present invention can be implemented using a sensor circuit that does not include an AGC circuit. It has been found that the latter embodiment allows operation at a faster cycle time as compared with the former embodiment, thereby providing improved accuracy. In the configuration shown inFIG. 6, all the transmit components54and receive components are active simultaneously, therefore, to initiate the beam sequence of step S102, the system controller16merely activates the entire infrared sensor array22.

FIG. 7illustrates an alternative configuration of the infrared sensor array22. Similar to the arrangement shown inFIG. 6, all the transmit components54are located on the same sensor panel22aand the receive components56are located on the opposite sensor panel22b. However, in this configuration, the controller28sequences the beams at a rapid pace wherein only a single pair of sensors are active at any one time. One embodiment of the present invention uses a sequencing rate of 200 Hz. For example, inFIG. 7, transmit sensor54atransmits during the first firing round (Firing round A) and only receive sensor56ais active to receive. During the second firing round (Firing round B), transmit sensor54btransmits and only receive sensor56bis active to receive. Each pair of infrared sensors are activated in turn until all the sensors have fired and the sequence begins again with the first pair of sensors. In this manner, the receive sensors56are guaranteed to only receive signals initiated from the corresponding transmit sensor54of the sensor pair, thereby eliminating false triggers from adjacent beams and improving overall sensitivity. Additionally, this sequencing mechanism allows for the use of less expensive infrared sensors (as compared with the sensors inFIG. 6) as each beam is not required to have a very narrow, focused beam—a feature which increases the piece-part cost of infrared sensor pairs. The use of a less focused beam allows for easier alignment of the transmit sensor54and the receive sensor56.

FIG. 8illustrates an alternative configuration of the infrared sensor array22. In this configuration, the transmit components54and the receive components56are alternated between infrared sensor panel22aand infrared sensor panel22bin order to improve discretion between adjacent infrared beams26.

FIG. 9illustrates another alternative configuration of the infrared sensor array22, in which the physical configuration ofFIG. 8, i.e. transmitting components54alternated with receiving components56, is combined with the firing sequence shown inFIG. 7to provide an even greater discretion between adjacent beams26and further minimize false triggers.

Returning now toFIG. 5, the beam sequence runs in a continuous cycle as long as no beams are broken (step S102). When the system controller16detects that a beam has been broken (step S104), the cart detection module50monitors the infrared sensor array22to determine whether the present beam breakage pattern matches the expected pattern for a wheel (step S106). For example, an expected pattern for a wheel may be that each beam is broken sequentially for a given number of beams, up to and including all beams, and only a given number of beams is broken at any time. If the pattern does not match the expected pattern for a wheel, the cart detection module50compares the breakage pattern to the expected pattern for a human walking (step S108). An expected pattern for a person walking may be that up to a predetermined number of beams are simultaneously broken and/or not all the beams of the array are triggered. If the pattern matches a person walking, then the people counter20is incremented (step S110) and the process ends. If the pattern does not match the expected pattern for a person walking (step S108), the cart detection module50returns to decision block S104to detect if any other beams have been broken, thereby changing the current breakage pattern.

Returning to decision block S106, if the current breakage pattern matches the expected pattern for a wheel, the system controller16determines whether the metal detection module48has detected the presence of metal within the interrogation zone (step S112). The metal detection module48may simply indicate the presence of metal within the interrogation zone or may return a response reading proportional to the amount of metal detected, in which case, the system controller16determines whether the response reading is greater than a predetermined threshold indicative of a response generated by a large metal object, such as a cart. If metal is not detected, the process ends. However, if there is metal present (step S112), the system controller16prevents the metal detection module48from generating an alarm indicating the presence of a metal shield (step S114). Similarly, if the metal detection module48detects metal in the interrogation zone and the cart detection module50determines that no cart is present, the system controller16may instruct the metal detection module48to generate an alarm indicating the presence of a metal shield. The process illustrated inFIG. 5may be repeated continuously or at a predetermined interval.

Referring now toFIG. 10, the method ofFIG. 5is capable of accurately detecting a cart24or other wheeled-device as long as the cart is actually moving through the interrogation zone and breaking the infrared beams26. However, when the cart24stops midway through the pedestals12, as shown inFIG. 11, or when other items remain stationary between the pedestals12, one or more sensor pairs become blocked, subsequently not functioning properly.

Referring now toFIG. 12, a flowchart is provided that describes exemplary steps performed by the EAS system10to detect one or more blocked sensor pairs. The system controller16enables the infrared sensor arrays22by activating a beam sequence as above in the cart detection process detailed inFIG. 5(step S116). If a single beam is broken (step S118), then the real-time clock52begins a countdown timer (step S120).

The countdown timer may be set for a predetermined amount of time, e.g., 30 seconds, 1 minute, etc. The countdown timer is started as soon as a beam is broken. As long as the countdown timer has not reached a terminal count (step S122), i.e. t=0, then the cart detection module50continues to monitor the blocked sensor to determine if the sensor becomes unblocked (step S124). If the sensor becomes unblocked, then the system controller16sets the status of the sensor to active (step S126) and returns to decision block S118to continue monitoring for blocked sensors. However, if the countdown timer reaches the terminal count without the blocked sensor becoming unblocked (step S124), the cart detection module50sets the status of the blocked sensor to inactive and does not use the blocked sensor in the cart detection process (step S128). The blocked sensor may be returned to active status if the previously blocked sensor has become unblocked by repeating the blocked sensor process. It is noted the starting value of the countdown timer can be set sufficiently large as to not create fall blockage triggers.

In the case where the blocked sensor process determines that multiple beams are blocked, such as might occur if a cart is left in the interrogation zone, a person lingers in the interrogation zone too long or even where some other object is blocking multiple sensors, it is contemplated that the system can alert the store manager or some other designated personnel.

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 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.

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.