HK1184587B - System and method using proximity detection for reducing cart alarms and increasing sensitivity in an eas system with metal shielding detection - Google Patents

Description

System and method using proximity detection for reducing cart alarms and increasing sensitivity of EAS systems with metal shield detection

Technical Field

The present invention relates generally to electronic article surveillance ("EAS") systems and, more particularly, to a method and EAS system for detecting objects entering an area for detecting metal and magnetic materials to reduce false alarms caused by the presence of metal carts within an EAS interrogation zone.

Background

Electronic article surveillance ("EAS") systems are commonly used in retail stores and other settings to prevent unauthorized removal of goods from a protected area. Typically, the system is deployed at an exit of a protected area, and the system includes one or more transmitters and antennas ("pedestals") capable of generating an electromagnetic field (referred to as an "interrogation zone") on either side of the exit. Articles to be protected from removal are tagged with an EAS marker that, when activated, generates an electromagnetic response signal when passing through the interrogation zone. The antenna and receiver within the same or another "base" detect the response signal and generate an alarm.

Due to the nature of this process, other magnetic materials or metal objects, such as metal carts positioned near an EAS marker or transmitter, may interfere with the optimal performance of the EAS system. In addition, some unscrupulous individuals may be shielded with EAS markers, such as foil, intended to steal the in-store merchandise without being detected by any EAS system. The metal can shield tagged items from the EAS detection system.

Current EAS systems for implementing metal shield detection mechanisms are sometimes fooled by various cart configurations and may be power overloaded by responses to large amounts of metal. Some systems attempt to overcome this problem by reducing the system gain, which can limit detection sensitivity and reduce the ability to detect small items (e.g., metal shields that these systems seek to detect).

Other conventional systems may include a "cart inhibit" feature in an EAS system/metal detection configuration. By monitoring the total amount of metallic response signals, a threshold value indicative of a suppression condition can be achieved so that the system does not erroneously generate an alarm. However, even if such a scheme is implemented, certain store goods continue to fool the system and result in false alarms or missed detections. For example, the detection of large metal masks located near the pedestal may be reduced because these masks produce a readout that exceeds a threshold.

Accordingly, what is needed is a system and method for individually detecting objects entering a metal detection zone to predict the presence of a cart or stroller within an EAS interrogation zone, thereby allowing for increased sensitivity of EAS systems having metal shield detection capabilities.

Disclosure of Invention

The present invention advantageously provides a method and system for detecting electronic article surveillance ("EAS") marker shielding by separately detecting the presence of a cart or other wheeled device within an EAS interrogation zone. In general, the present invention is able to distinguish a wheeled device from a person walking between bases by examining the pattern of interruptions from sensors located on the base directly above the floor.

In one aspect of the invention, a system for detecting electronic article surveillance ("EAS") marker shielding includes an EAS subsystem, a metal detector, an object detector, a timer, a cart detection subsystem, and a processor. The EAS subsystem is operable to detect EAS markers within the interrogation zone. The metal detector is operable to detect a metal object within the interrogation zone. The object detector is operable to detect objects located near an entry point of the EAS subsystem. The timer is programmed to initiate a countdown sequence upon receiving a signal generated by the object detector. The cart detection subsystem includes a sensor array. The cart detection subsystem is operable to detect wheeled devices passing through the interrogation zone based on the output of the sensor array. The processor is electrically coupled to the EAS subsystem, the metal detector, the object detector, the timer, and the cart detection subsystem. The processor is programmed to receive signals from the object detector and the timer to begin collecting information output by the cart detection subsystem and information output by the metal detector to determine whether to generate an alarm signal based on the presence of EAS marker shielding.

In accordance with another aspect of the invention, a method for detecting EAS marker shielding is provided. The presence of an object within the interrogation zone is detected. A countdown timer is started and a metal object is detected within the interrogation zone. A determination is made as to whether the wheeled device is passing through the interrogation zone. In response to determining that no wheeled device is passing through the interrogation zone, and upon detection of a metallic object, an alarm signal is generated after expiration of a countdown timer to notify the presence of EAS marker shielding.

In accordance with yet another aspect of the invention, an EAS system controller for use with a metal detector includes an EAS subsystem, an object detector, a timer, a communication interface, a cart detection subsystem, and a processor. The EAS subsystem is operable to detect EAS markers within the interrogation zone. The object detector is operable for objects located near an entry point of the EAS subsystem. The timer is programmed to initiate a countdown sequence upon receiving a signal generated by the object detector. The communication interface is operable to receive inputs from the metal detector, the object detector, and the timer. The cart detection subsystem includes a sensor array and is operable to distinguish between a wheeled device and a person passing through the interrogation zone based on an output of 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 signals from the object detector and the timer to begin collecting information output by the cart detection subsystem and information output by the metal detector to determine whether to generate an alarm signal based on the presence of EAS marker shielding.

Drawings

A more complete understanding of the present invention, and the advantages and features thereof, may be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of an exemplary electronic article surveillance ("EAS") detection system having zone entry detection, metal detection, cart detection, and people counting capabilities constructed in accordance with the principles of the present invention;

FIG. 2 is a side perspective view of a cart being passed through the exemplary EAS system of FIG. 1 constructed in accordance with the principles of the present invention;

FIG. 3 is a front perspective view of a cart being passed through the exemplary EAS system of FIG. 1 constructed in accordance with the principles of the present invention;

FIG. 4 is a block diagram of an exemplary EAS system controller constructed in accordance with the principles of the present invention;

FIG. 5 is a flow chart of an exemplary cart detection process according to the principles of the present disclosure;

FIG. 6 is a block diagram of an exemplary infrared detection sensor configuration constructed in accordance with the principles of the present invention;

FIG. 7 is a flow chart illustrating one exemplary emission sequence of the infrared detection sensor configuration of FIG. 6 in accordance with the principles of the present invention;

FIG. 8 is a block diagram of an alternative infrared detection sensor configuration constructed in accordance with the principles of the present invention;

FIG. 9 is a flow chart illustrating one exemplary emission sequence of the infrared detection sensor configuration of FIG. 8 in accordance with the principles of the present invention;

FIG. 10 is a side perspective view of a cart passing unobscured through a sensor beam of the exemplary EAS system of FIG. 1 in accordance with the principles of the present invention;

FIG. 11 is a side perspective view of a cart housing at least one sensor beam of the exemplary EAS system of FIG. 1, according to the principles of the present invention;

FIG. 12 is a flow chart of an exemplary occlusion sensor detection process in accordance with the present invention;

FIG. 13 is a top view of a cart entering an EAS detection system within the field of view of a passive infrared ("PIR") detector; and

fig. 14 is a flow chart of an exemplary object detection process in accordance with the principles of the present invention.

Detailed Description

Before describing in detail exemplary embodiments that are in accordance with the present invention, it should be observed 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 an object (e.g., a cart or stroller) entering the field of view of a passive infrared ("PIR") detector positioned near an entry point of an EAS interrogation zone. The PIR detector is positioned to detect an object before the object enters the EAS interrogation zone, thereby allowing the system to initiate a timeout mode rather than adjusting the sensitivity level of an EAS system having EAS marker shield detection capabilities. Upon detection of an object, the PIR detector starts a timer within the foil bag detection system and suppresses metal detection or suppresses an alarm signal for a predetermined period of time in order to reduce false alarms due to metal carts. The predetermined period of time is set for an expected amount of time that the metal cart travels from the initial PIR detection point through an infrared wheel detector positioned within the EAS interrogation zone (i.e., to a point within the wheel detector where a determination can be made as to whether a wheeled device is present).

Accordingly, the components of the systems and methods are 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.

An embodiment of the present invention advantageously provides a method and system for detecting the presence of an object (e.g., a cart or stroller) within the field of view of a detector (e.g., a passive infrared ("PIR") detector) positioned near an entry point of an EAS interrogation zone. The PIR detector is positioned to detect an object before the object enters an interrogation zone of the EAS system. The PIR detector sends a signal to the foil bag detection system to start a timer that is preprogrammed with an expected amount of time that the metal cart has traveled from an initial PIR detection point through an infrared wheel detector positioned within the EAS interrogation zone (i.e., at least to a point within the wheel detector where a determination can be made as to whether a wheeled device is present). The EAS system does not attempt to detect EAS marker shielding for a preprogrammed amount of time. Alternatively, the EAS system does not generate an alarm signal when EAS marker shielding or other metallic objects are detected for a preprogrammed amount of time. In other words, the EAS system enters a timeout period upon detecting an object entering the EAS interrogation zone, rather than suppressing the sensitivity of the system or initiating an alarm signal. The EAS system combines conventional EAS detection capabilities with PIR detectors positioned near an array of infrared sensors located on the base of a set of EAS pedestals located near the floor to detect the motion of objects expected to pass through the interrogation zone.

Referring now to the drawings in which like reference designators refer to like elements, there is shown in FIG. 1 one configuration of an exemplary EAS detection system 10 constructed in accordance with the principles of the present invention and located, for example, at an entrance to a facility. The EAS detection system 10 includes a pair of pedestals 12a, 12b (collectively pedestals 12) on opposite sides of an entrance 14. One or more antennas of the EAS detection system 10 may be contained within pedestals 12a and 12b located a known distance apart. The antenna located within the pedestal 12 is electrically coupled to a control system 16 for controlling the operation of the EAS detection system 10. The system controller 16 is electrically connected to the metal detector 18, the people counting system 20, the infrared sensor array 22, and the zone entry detector 23 to more accurately detect the presence of a foil lined bag. The infrared sensor array 22 includes a pair of infrared sensor panels 22a, 22b (collectively referred to as "infrared sensor array 22"). It is also contemplated that other types of sensor arrays can be used, such as pressure sensitive pads or the like arranged to provide data indicating where pressure or the like has been applied.

The metal detector 18 may be a separate unit communicatively coupled to the system controller 16 or may be integrated within the system controller 16. U.S. patent application No.12/492,309, entitled Electronic Article monitoring System with Metal detection capability and Method therefor, filed on 26.6.2009, discloses an exemplary Metal detector 18, which is incorporated by reference herein in its entirety.

The zone entry detector 23 may comprise a PIR detector in addition to other zone entry detectors. The area entry detector 23 may be mounted on the infrared sensor array 22. According to one embodiment, the zone entry detector 23 includes two PIR detectors positioned on the sensor array 22 at heel height or about 2 inches from floor level. The area entry detector 23 may be installed at a detector side of the infrared sensor panel, and may be concentrated on the sensor array 22 in a height direction, and may be disposed at opposite sides of the sensor array 22 in a lateral direction. The two PIR detectors may operate together to detect movement of an object through the interrogation zone. For example, the two PIR detectors may operate together to detect an object entering the interrogation zone after an object outside the interrogation zone exits. According to one embodiment, the signals from the two PIR detectors may be compared to determine the amount of time spent by an object passing through the interrogation zone. Alternatively, the two PIR detectors may operate individually to detect the entry or exit of an object through the interrogation zone. The zone entry detector 23 may comprise PIR detectors arranged within a pelmet zone such that any PIR detector will detect an object entered by the entry point.

The people counting system 20 may be a separate device (e.g., an overhead people counter) and may be physically located within one or more pedestals 12 and/or integrated into the system controller 16. The people counting system may include, for example, one or more infrared sensors mounted about 8-14 feet (2.5-4.3 m) above the entrance/exit of the retail store. Integrating the people counting sensor into the EAS detection pedestal 12 helps ensure a simple and efficient method for communicating basic operational information. In operation, a people counter detects the movement of people into, through, or out of a predetermined area. This information is collected and processed by the people counting system 200, for example, using a programmed microprocessor. The demographic data may then be transmitted to other portions of the EAS detection system 10 using conventional network components. The demographic data may be transmitted over the store's internal network or over a wide area network (e.g., the internet), where the data can be categorized, reported and studied.

Referring now to fig. 2 and 3, perspective views of the cart 24 through the exemplary EAS system 10 are provided. As can be seen in FIG. 2, the infrared sensor array 22 is located at the base of the base 12 at a height of about 1/4 (6.4 mm) -2 inches (51 mm) from the floor. The length of the infrared sensor array 22 should be at least 6-12 inches (152 mm-305 mm) to allow for differentiation of the pattern of interruption of the infrared beam 26 between the wheel and the human foot. The array of infrared sensors 22 is arranged so that the sensors produce a plurality of parallel beams 26 between the pedestals 12, as shown in fig. 3. Because the beam is close to the floor, the beam 26 is interrupted by the wheels of the cart 24, stroller, or other wheeled object passing between the bases 12. The light beam 26 is also interrupted when a person walks between the pedestals. But instead. The interruption pattern for a person walking through the light beam 26 is different than the interruption pattern for a cart 24 rolling through the light beam 26.

For example, the cart 24 may sequentially interrupt the light beams 26 and may pass each light beam 26, since the wheels of the cart 24 never exit the floor. In contrast, a person walking through the beams 26 may interrupt several beams 26 at the same time but does not necessarily interrupt each beam 26 in the array 22. By recognizing the differences in these interruption patterns, embodiments of the present invention are able to distinguish the stroller 24 or stroller from other metal objects. The system can use this information to improve the sensitivity and accuracy of its foil lined bag detection. The operation of the infrared sensor array 22 (in conjunction with the system controller 16) will be discussed in more detail below.

Referring now to fig. 4, an exemplary EAS system controller 16 may include a controller 28 (e.g., a processor or microprocessor), a power supply 30, a transceiver 32, a memory 34 (the memory 34 may include non-volatile memory, or a combination thereof), a communication interface 36, and an alarm 38. The controller 28 controls radio communication, data storage of the memory 34, communication of stored data to other devices, and activation of the alarm 38. A power supply 30 (e.g., a battery or ac power supply) powers the EAS control system 16. The alarm 38 may include software and hardware for providing a visual and/or audible alarm in response to the detection of an EAS marker and/or metal within the interrogation zone of the EAS system 10.

The transceiver 32 may include a transmitter 40 electrically coupled to one or more transmit antennas 42 and a receiver 44 electrically coupled to one or more receive antennas 46. Alternatively, a single antenna or a pair of antennas may be used as both the transmit antenna 42 and the receive antenna 46. The transmitter 40 uses a transmit antenna 42 to transmit radio frequency signals to "power" EAS markers within the interrogation zone of the EAS system 10. The receiver 44 uses the receive antenna 46 to detect the response signal of the EAS marker. It is also contemplated that the exemplary system 10 can include the transmitting antenna 42 and receiver 44 in one base (e.g., base 12 a), and the reflective material in another base (e.g., base 12 b).

The memory 34 may include a metal detection module 48 for detecting the presence of metal within the interrogation zone, a zone entry detector 49 for detecting the presence of an object near an entry point of the interrogation zone, and a cart detection module 50 for determining whether the detected metal is a cart, baby carriage, or other wheeled object (e.g., a wheelchair, hand truck, etc.). The operation of the metal detection module 48, the zone entry detector 49 and the cart detection module 50 will be described in more detail below.

The metal detection module 48 and the zone entry detector 49, along with the cart detection module 50, are used to determine whether to trigger the alarm 38 by analyzing the output information received from the metal detector 18, the people counting system 20, the infrared sensor array 22, and the zone entry detector 23 via the communication interface 36. For example, if zone entry detector 49 detects the presence of an object near the interrogation zone, controller 28 sends a signal to metal detection module 48 to initiate a timeout period for the amount of time expected for the object to enter the interrogation zone.

If, after expiration of the timeout period, the cart detection module 50 detects the passage of a person through the interrogation zone by the beam break mode and the metal detector 18 detects a metal source that meets the characteristics of the metal shield, the metal detection module 48 may trigger the alarm 38 by sending an alarm signal via the controller 28. The alarm 38 alerts store security or other authorized personnel who may monitor or process the individual as authorized.

Alternatively, if after expiration of the timeout period, the cart detection module 50 detects that the cart has passed through the interrogation zone based on the beam break pattern, and the metal detector 18 detects a metal source that is consistent with the characteristics of the metal shield, the metal detection module 48 will not trigger the alarm 38.

The controller 28 may also be electrically coupled to a real time clock ("RTC") 52 for monitoring the passage of time. The RTC52 may serve as a timer for the metal detection module 48 to determine whether an action of an event (e.g., metal detection or people counting) occurred within a predetermined time range. The RTC52 may also be used to generate a timestamp so that the time of an alarm or event detection may be recorded.

Referring now to fig. 5, a flowchart is provided that describes exemplary steps performed by the EAS system 10 to determine whether an object passing through the pedestal 12 is a cart 24 or other wheeled device. The system controller 16 enables the infrared sensor array 22 by activating a sequence of light beams depending on the configuration of the infrared sensor array 22 (step S102).

The infrared sensor array 22 may be configured in a variety of ways. For example, as shown in FIG. 6, the infrared sensor array 22 may have one sensor panel 22a that includes only emitting members 54a-54j (collectively, "emitting members 54"), and a second sensor panel 22b that includes only receiving members 56a-56j (collectively, "receiving members 56"). It should be noted that although fig. 6 shows 10 pairs of infrared sensors, the number of sensor pairs shown is for illustrative purposes only, and any number of sensor pairs that can reliably produce a recognizable interrupt pattern may be selected for implementation. For example, the present invention has found that: using 5 pairs of sensors can perform satisfactorily. Also, while any sensor spacing can be used, so long as the spacing allows the determination described herein with respect to a wheeled cart's human footfall, one embodiment of the invention is implemented with sensors that are approximately 2.75-3.00 inches (69.9-76.0 mm) apart.

Although sensors with focused elements are preferred, the invention can be implemented using non-focused elements. Also, while an automatic gain control ("AGC") circuit can be used as a component 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 than the former embodiment, thereby providing improved accuracy. In the configuration shown in fig. 6, all the emitting means 54 and the receiving means are active synchronously. Therefore, to initiate the beam sequence of step S102, the system controller 16 will activate the entire infrared sensor array 22.

Fig. 7 shows an alternative configuration of the infrared sensor array 22. Similar to the configuration shown in fig. 6, all of the transmitting members 54 are located on the same sensor panel 22a, and the receiving members 56 are located on the opposite sensor panel 22 b. However, in this configuration, the controller 28 sequences the beams rapidly, with only one pair of sensors active at any one time. One embodiment of the invention uses a sequencing rate of 200 Hz. For example, in fig. 7, transmit sensor 54a transmits in a first transmit round (transmit round a), and only receive sensor 56a is active and available for reception. During the second transmit round (transmit round B), transmit sensor 54B transmits, and only receive sensor 56B is active, available for reception. Each pair of infrared sensors is activated in turn until all sensors have emitted, and the sequence starts again with the first pair of sensors. In this way, it can be ensured that the receiving sensor 56 receives only signals that start at the respective transmitting sensor 54 of the sensor pair, thereby excluding false triggers from adjacent beams and increasing the overall sensitivity. In addition, this sequencing mechanism allows the use of less expensive infrared sensors (as compared to the sensor in FIG. 6) because each beam does not need to have a narrow focused beam that adds to the cost of the components of the infrared sensor pair. Also, the use of a less focused beam makes it easier to align the transmit sensor 54 with the receive sensor 56.

Fig. 8 shows an alternative configuration of the infrared sensor array 22. In this configuration, the emitting members 54 and receiving members 56 are staggered between the infrared sensor panels 22a and 22b to improve discrimination between adjacent infrared beams 26.

Fig. 9 shows another alternative configuration of the infrared sensor array 22 in which the physical configuration of fig. 8 (i.e., the emitting members 54 interleaved with the receiving members 56) is combined with the emission sequence shown in fig. 7 to provide even greater discrimination between adjacent beams 26 and further minimize false triggering.

Referring now to fig. 5, the sequence of beams is run in a continuous cycle as long as no beam is interrupted (step S102). When the system controller 16 detects that the light beam has been interrupted (step S104), the cart detection module 50 monitors the infrared sensor array 22 to determine whether the current beam interruption pattern matches the expected pattern of the wheels (step S106). For example, the expected pattern of wheels may be: for a given number of beams, including at most all beams, each beam is interrupted in turn, and only a given number of beams are interrupted at any one time. If the pattern does not match the expected pattern of wheels, the cart detection module 50 compares the interrupted pattern to an expected pattern of human walking (step S108). The expected pattern of human walking may be: up to a predetermined number of beams are interrupted simultaneously and/or not all beams of the array are triggered. If the pattern matches the walking of the person, the person number counter 20 is incremented (step S110) and the process ends. If the pattern does not match the expected pattern of human walking (step S108), the cart detection module 50 returns to decision block S104 to detect if any other light beams have been interrupted, thereby changing the current interruption pattern.

Returning to decision block S106, if the current interrupt pattern matches the expected pattern of the wheel, the system controller 16 determines whether the metal detection module 48 has detected the presence of metal within the interrogation zone (step S112). The metal detection module 48 may simply indicate that metal is present within the interrogation zone or may return a response reading proportional to the amount of metal detected, in which case the system controller 16 determines whether the response reading is greater than a predetermined threshold indicative of a response generated by a large metal object (e.g., a cart). If no metal is detected, the process ends. However, if metal is present (step S112), the system controller 16 prevents the metal detection module 48 from generating an alarm indicating the presence of a metal shield (step S114). Similarly, if the metal detection module 48 detects metal within the interrogation zone and the cart detection module 50 determines that a cart is not present, the system controller 16 may instruct the metal detection module 48 to generate an alarm indicating the presence of a metal shield. The process shown in fig. 5 may be repeated continuously or at predetermined intervals.

Referring now to fig. 10, the method of fig. 5 is capable of accurately detecting a cart 24 or other wheeled device as long as the cart is actually moving through the interrogation zone and interrupting the infrared beam 26. However, when the cart 24 stops part way through the base 12, as shown in FIG. 11, or when other items remain stationary between the bases 12, one or more sensor pairs become blocked and essentially do not function properly.

Referring now to fig. 12, a flowchart is provided that describes exemplary steps performed by the EAS system 10 to detect one or more blocked sensor pairs. The system controller 16 enables the infrared sensor array 22 by activating a light beam sequence as in the cart detection process detailed in fig. 5 above (step S116). If the single beam is interrupted (step S118), the real time clock 52 starts a countdown timer (step S120).

The countdown timer may be set for a predetermined amount of time (e.g., 3 seconds). The countdown timer starts when the light beam is just interrupted. As long as the countdown timer has not reached the final count (i.e., t = 0) (step S122), the cart detection module 50 continues to monitor the blocked sensor to determine whether the sensor has become unblocked (step S124). If the sensor becomes unblocked, the system controller 16 sets the status of the sensor to active (step S126) and returns to decision block S118 to continue monitoring the blocked sensor. However, if the countdown timer reaches a final count without the blocked sensor becoming unblocked (step S124), the cart detection module 50 sets the state of the blocked sensor to inactive and does not use the blocked sensor during cart detection (step S128). A blocked sensor may return to an active state if a previously blocked sensor has become unblocked by repeating the blocked sensor process. It should be noted that the starting value of the countdown timer can be set large enough so as not to generate false blocking triggers.

In the case where the blocked sensor process determines that multiple beams are blocked, such as may occur if a cart is left in the interrogation zone, a person remains in the interrogation zone for too long, or even if some other object is blocking multiple sensors, it is contemplated that the system can alert store management personnel or some other designated person of the system's condition.

Referring now to FIG. 13, an infrared sensor array 22 and PIR detectors 1302, 1304 are disposed at the base 12. One sensor panel 22a including only emitting members 54a-54e (collectively, "emitting members 54") is disposed on a first side of base 12 a. A second sensor panel 22b that includes only receiving members 56a-56e (collectively, "receiving members 56") is disposed on a second side of base 12 b. It should be noted that while fig. 13 shows 5 pairs of infrared sensors, the number of sensor pairs shown is for illustrative purposes only, and any number of sensor pairs that can reliably produce a recognizable interrupt pattern may be selected for implementation.

Figure 13 shows PIR detectors 1302, 1304 disposed on a second or detector side of the base 12b between selected receiving members 56a-56 e. For example, the PIR detector 1302 may be disposed between the receiving means 56a and 56b to monitor the PIR detection region 1306 at a first entry point. A second PIR detector 1304 may be disposed between the receiving means 56d and 56e to monitor the PIR detection region 1308 at a second access point. It should be noted that although fig. 13 shows two PIR detectors, the number of PIR detectors shown is for illustrative purposes only. For example, the system may operate as described above in conjunction with a single PIR detector.

According to one embodiment, the PIR detectors 1302, 1304 and sensor array may be positioned 2 inches or less from floor level. One skilled in the art will readily recognize that the PIR detector and sensor array may be positioned at other heights. As shown in fig. 13, magnetic field 1210 projects laterally beyond base 12. The PIR detector 1302 is positioned to detect an object in the PIR detection zone 1306 before the object is detected by the magnetic field 1310.

Upon detecting the presence of the cart 24, the PIR detector 1302 sends a signal to a foil bag detection system within the system controller 16 (not shown) to start a timer that is preprogrammed with an expected amount of time that the cart has traveled from an initial PIR detection point through the infrared sensor array 22 positioned within the EAS interrogation zone (i.e., at least to a point within the sensor array 22 at which a determination can be made by the cart detection module 50 as to whether a wheeled device is present within the EAS interrogation zone). The EAS system does not attempt to detect EAS marker shielding for a preprogrammed amount of time. Alternatively, if a metallic object is detected, the EAS system may suppress the alarm signal for a preprogrammed amount of time. For example, rather than suppressing the sensitivity of the system or initiating an alarm signal, the EAS system enters a timeout period upon detecting the entry of the shopping cart 24 into the EAS interrogation zone. The present invention combines conventional EAS detection capabilities with PIR detectors 1302, 1304 positioned near an array of infrared sensors located on the base of a set of EAS pedestals located near the floor. The PIR detector 1302 detects the presence of a shopping cart 24 that is expected to pass through the interrogation zone.

Upon expiration of the timeout period, the metal detector 18 (not shown) attempts to sense metal or the alarm 38 (not shown) is activated. If, after expiration of the timeout period, the cart detection module 50 (not shown) detects 1320 that the cart 24 has not broken the light beam 1312 based on the light beam interruption pattern and the metal detector 18 detects a metal source that is characteristic of metal shielding, the metal detection module 48 (not shown) may trigger the alarm 38 (not shown) by sending an alarm signal via the controller 28 (not shown). The alarm 388 alerts store security or other authorized personnel who may monitor or process individuals as authorized. For example, the beam break pattern may correspond to a non-shopping cart or a human foot that breaks one or more of the beams 1312-1320.

Alternatively, if after the expiration of the timeout period, the cart detection module 50 detects that the cart 24 passes through the interrogation zone based on the appropriate pattern of interruption of the light beams 1312 and 1320, and the metal detector 18 detects a metal source that is characteristic of the metal shield, the metal detection module 48 will not trigger the alarm 38.

Referring now to fig. 14, a flow chart is provided for describing an exemplary process performed by the EAS system 10 to suppress false alarm signals for detectors of metal detection. The system controller 16 enables the zone entry detector 49 to detect whether an object is detected by the PIR detector 1302 in the PIR detection zone 1306 (step S1402).

If an object is detected, the real-time clock 52 starts a countdown timer (step S1404). The countdown timer may be set for a predetermined amount of time (e.g., 1 second, 3 seconds, 1 minute, etc.). A countdown timer is started upon detection of an object. A determination is made as to whether metal is detected by metal detection module 48 (e.g., whether a metal foil lined pouch is present) (step S1406). If metal is not detected, the system continues to check for the presence of metal as long as the countdown timer has not reached the final count (i.e., t = 0) (step S1408). If the final count has been reached, the process ends (and restarts).

If metal is detected at step 1406 and the cart detection module 50 detects the presence of a wheel (step 1410), the metal detection module 48 is maintained in an inactive state (step 1412). Alternatively, metal detection module 48 may remain in an active state and alarm 38 may be disabled. If the presence of a wheel is not detected at step S1410, the system continues to check for the presence of a wheel until a final count is reached (step S1414). If the final count is reached and the cart detection module 50 does not detect a wheel, the metal detection module 48 is activated (step 1416). Alternatively, the alarm 38 may be activated. Those skilled in the art will readily recognize that other techniques may be used to suppress the system response during the countdown timer.

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 media 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 a) conversion to another language, code or notation and/or b) reproduction in a different material form.

In addition, unless otherwise noted, it should be noted that not all of the figures are 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.

Claims (20)

1. A system for detecting Electronic Article Surveillance (EAS) marker shielding, the system comprising:

an EAS subsystem that detects EAS markers within an interrogation zone;

a metal detector that detects metal objects within the interrogation zone;

an object detector that detects objects located near an entry point of the EAS subsystem;

a timer programmed to initiate a countdown sequence upon receipt of a signal generated by the object detector;

a cart detection subsystem including a sensor array, the cart detection subsystem operable to detect a wheeled device passing through the interrogation zone based on an output of the sensor array; and

a processor electrically coupled to the EAS subsystem, the metal detector, the object detector, the timer, and the cart detection subsystem, the processor programmed to receive signals from the object detector and the timer to begin collecting information output by the cart detection subsystem and information output by the metal detector to determine whether to generate an alarm signal based on the presence of EAS marker shielding.

2. The system of claim 1, wherein the interrogation zone is located between a pair of EAS pedestals, each EAS pedestal having a base end positioned to rest on a floor, the base ends of the EAS pedestals comprising: the sensor array having a plurality of infrared sensor pairs, each infrared sensor pair including a transmitting member located on one EAS pedestal of the pair of EAS pedestals and a receiving member located on the other EAS pedestal of the pair of EAS pedestals, such that when activated, each infrared sensor pair forms an infrared beam between the pedestals; and

the object detector, including a passive infrared detector, is positioned on the same side of the EAS pedestal as the receiving members of the sensor array.

3. The system of claim 2, wherein each infrared beam and the passive infrared detector are positioned sufficiently above a base end of the pedestals such that the infrared beam is interrupted by wheels of the wheeled device rolling between the pedestals and the passive infrared detector detects the presence of an object.

4. The system of claim 2, wherein each infrared beam is positioned substantially parallel to the floor and substantially parallel to all other infrared beams.

5. The system of claim 4, wherein each infrared beam and the object detector are positioned at a height of 6.4-51 mm above the base end of the base.

6. The system of claim 2, wherein the plurality of infrared sensor pairs are activated simultaneously.

7. The system according to claim 1, further comprising a second object detector located near a second entry point of the EAS subsystem.

8. The system of claim 2, wherein the cart detection subsystem is operative to distinguish the wheeled device from a person passing through the interrogation zone by matching a pattern of interrupted infrared beams to one of an expected pattern of wheeled devices and an expected pattern of person walking.

9. The system of claim 8, wherein the expected mode of wheeled device includes sequential activation of each infrared sensor pair.

10. The system of claim 8, wherein the expected pattern of human walking comprises triggering more than one infrared sensor pair simultaneously.

11. The system of claim 1, wherein the processor generates the alert signal in response to:

the metal detector detects the metal object within the interrogation zone; and is

The cart detection subsystem determines that no wheeled device is passing through the interrogation zone.

12. A method for detecting Electronic Article Surveillance (EAS) marker shielding, the method comprising:

forming a plurality of interruptible beams within an interrogation zone;

detecting the presence of an object within the interrogation zone;

starting a countdown timer to detect expiration of the timeout period;

detecting a metallic object within the interrogation zone;

determining that a wheeled device is passing through the interrogation zone if the pattern of the interrupted light beam matches an expected pattern of the wheeled device;

determining that a person is passing through the interrogation zone if the pattern of the interrupted light beam matches an expected pattern of walking of the person; and

upon detecting expiration of the timeout period, generating an alert signal notifying the presence of EAS marker shielding based at least in part on detecting the metallic object and determining that a person is passing through the interrogation zone.

13. The method of claim 12, wherein the interrogation zone is formed between a pair of EAS pedestals, each EAS pedestal having a base end positionable on a floor, wherein the plurality of interruptible optical beams are formed by a sensor array comprising:

a plurality of infrared sensor pairs, each infrared sensor pair comprising a transmitting member located on one EAS pedestal of the pair of EAS pedestals and a receiving member located on the other EAS pedestal of the pair of EAS pedestals, such that when activated, each infrared sensor pair forms one of a plurality of interruptible beams of light between the pedestals, each interruptible beam of light is an infrared beam, and

disposing a passive infrared detector on the EAS pedestal on the same side as a receiving member of the sensor array.

14. The method of claim 13, further comprising positioning each infrared beam sufficiently above the base end such that each infrared beam is interrupted by a wheel of the wheeled device rolling between the bases and the passive infrared detector is capable of detecting the presence of an object near the interrogation zone.

15. The method of claim 13, further comprising: if a determination is made that the pattern of the interrupted light beam does not match the expected pattern of the wheeled device and the expected pattern of human walking, then a determination is made as to whether other light beams have been interrupted.

16. The method of claim 13, further comprising:

determining that at least one infrared sensor pair is blocked; and

deactivating the at least one infrared sensor pair based at least in part on determining that the at least one infrared sensor pair is blocked.

17. An Electronic Article Surveillance (EAS) system controller for use with a metal detector, the EAS system controller comprising:

an EAS subsystem that detects EAS markers within an interrogation zone;

an object detector that detects objects located near an entry point of the EAS subsystem;

a timer programmed to initiate a countdown sequence upon receipt of a signal generated by the object detector;

a communication interface that receives inputs from the metal detector, the object detector, and the timer;

a cart detection subsystem including a sensor array, the cart detection subsystem operable to distinguish a wheeled device passing through the interrogation zone from a person based on an output of the sensor array; and

a processor electrically coupled to the EAS subsystem, the communication interface, and the cart detection subsystem, the processor programmed to receive signals from the object detector and the timer to begin collecting information output by the cart detection subsystem and information output by the metal detector to determine whether to generate an alarm signal based on the presence of EAS marker shielding.

18. The EAS system controller of claim 17, wherein the interrogation zone is formed between a pair of EAS pedestals, each EAS pedestal being positioned to rest on a floor, the EAS pedestals comprising:

an infrared sensor array comprising a plurality of infrared sensor pairs, each infrared sensor pair comprising a transmitting member located on one EAS pedestal of the pair of EAS pedestals and a receiving member located on the other EAS pedestal of the pair of EAS pedestals, such that when activated, each infrared sensor pair forms an infrared beam between the pedestals; and

the object detector, including a passive infrared detector, is positioned on the same side of the EAS pedestal as the receiving members of the sensor array.

19. The EAS system controller of claim 18, wherein the cart detection subsystem distinguishes between a wheeled device and a person passing through the interrogation zone by matching a pattern of interrupted infrared beams to one of an expected pattern of wheeled devices and an expected pattern of person walking.

20. The EAS system controller of claim 18, wherein each infrared beam and the passive infrared detector are positioned over a base end of the pedestals such that the infrared beam is interrupted by wheels of the wheeled device rolling between the pedestals and the passive infrared detector detects the presence of an object.