Abstract:
A system for controlling door-mounted or door-embedded antennas. An antenna, for example, an EAS or an RF antenna, sends interrogation signals which are received by markers located on merchandise within a range of detection, i.e., an “interrogation zone”. Antennas that are mounted on or embedded in a door move along with the motion of the door. Thus, the interrogation zone covered by the antenna&#39;s magnetic field is continually changing with the movement of the door. The system and method of the present invention control door-mounted antennas by monitoring the motion of the door upon which the antenna is mounted, and by adjusting the size and breadth of the interrogation zone generated by the antenna accordingly. A processor within a control unit receives positional signals from a position sensor mounted on the moving door, determines whether the interrogation zone should be increased, decreased, shut off, or maintained, and transmits signals to the antenna or to an alarm device, the signal containing interrogation zone modification instructions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Divisional of patent application Ser. No. 11/487,651, filed Jul. 17, 2006, entitled CONTROL FOR EMBEDDED AND DOOR-MOUNTED ANTENNAS, the entirety of which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    n/a 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Statement of the Technical Field 
         [0004]    The present invention relates to merchandise surveillance systems and more particularly to a system and method for monitoring the position of a door-mounted antenna, and altering the interrogation zone created by the antenna, depending upon the angle which the door containing the antenna is positioned relative to a reference plane. 
         [0005]    2. Description of the Related Art 
         [0006]    In a surveillance system, antennas such as EAS (“Electronic Article Surveillance”) antennas or RF (Radio Frequency) antennas, transmit interrogation signals that are received by markers such as Radio Frequency ID (RFID) or magneto acoustic markers located on merchandise within an establishment. The markers send corresponding signals back to the antenna. Thus, the interaction between the antennas and the markers establish an interrogation zone that can provide an establishment, such as a retail store, with a security system for its merchandise. Conventional surveillance systems include antennas located in a pedestal, the floor, the ceiling or wall or a combination of each such that the antennas can be used to monitor a large volume with the minimum number of antennas. While these types of systems are fine for large department stores and supermarkets, small shop retailers have different concerns since their security budgets may be lower and floor space may be at a great premium. 
         [0007]    One solution to the aforementioned problem faced by small retail stores is to mount one or more antennas on a swinging or sliding door. This allows retailers to utilize valuable floor, wall and/or counter space of merchandise, while still maintaining a security system. However, a problem that arises with this solution is that when the door is opened, the door-mounted antenna moves, and the resulting detection zone that is generated by the antenna also moves, possibly resulting in areas that now become out of reach of the antenna&#39;s detection zone. This is not a desired result in a small store that needs merchandise as close to the door exists as possible. 
         [0008]    A problem that arises when antennas are mounted on moving doors is that as the door is opening or closing, the antenna also moves, thus altering the originally-designed interrogation zone. The resulting location of the antenna may result in an over-range or an under-range condition. An over-range condition occurs when the magnetic field from the antenna covers a range of areas that includes locations where detection coverage is not needed. For example, a customer should be allowed to wait on line and approach a register holding an item having a marker without an alarm being set because the marked item has moved within the interrogation zone. This might occur when a door is swung into the store by the entrance of a new customer, and/or the exit of an existing customer, and the range of the magnetic field radiating from a door-mounted EAS antenna, or the range of RF signals transmitted by an RF antenna, which is moving along with the swinging door, coincides with the signal transmitted by the marker on an item being purchased by another customer on a check-out line. An over-range situation may also occur when the line for the cash register passes by an interrogation zone, or when a sliding door with an antenna moves laterally, moving marked items into the interrogation zone. 
         [0009]    An under-range condition occurs, for example, when a customer is exiting the store by swinging the door outward. In this case, because the antenna has moved along with the door, its interrogation zone may not cover a marked item near the exit of the store. Thus, a shoplifter who is approaching the door with a marked item when the door is opened by a new customer or an existing customer exiting the store, will not trigger an alarm since the door upon which the alarm is mounted has been swung outward, and the unadjusted magnetic field no longer coincides within signal transmitted by the marked item. 
         [0010]    Therefore, what is needed is a method and system that determines when a door containing an antenna is opened, in which the angle that the door is opened is monitored and measured with respect to a given reference plane, and controls the interrogation zone of the antenna to account for over-range and under-range conditions. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention addresses the deficiencies in the art with respect to door-mounted antennas. An antenna sends interrogation signals which are received by makers located on merchandise within a range of detection, i.e., an “interrogation zone”. The markers send corresponding signals back to the antenna. Antennas that are mounted on a door move along with the motion of the door. Thus, the interrogation zone covered by the antenna&#39;s magnetic field varies with the movement of the door. In some instances, an over-range or under-range condition is the result. In this regard, the system and method of the present invention are arranged to control door-mounted antennas by monitoring the motion of the door upon which the antenna is mounted, and by adjusting the size and breadth of the interrogation zone generated by the antenna accordingly. A processor within the controller receives positional signals from a position sensor mounted on the moving door, determines whether the interrogation zone should be increased, decreased, shut off, or maintained, in order to provide maximum store security subject to the store&#39;s size and physical and space limitations, and transmits signals to the antenna or to an alarm device, the signal containing interrogation zone modification instructions. 
         [0012]    According to one aspect, the present invention provides a system for controlling the interrogation zone of a door-mounted antenna. The system includes a door-mounted antenna having a transmitter component and a receiver component, and a sensor positioned proximate the door upon which the antenna is mounted. The sensor determines a distance that the door is moved in relation to a reference plane and transmits positional signals representative of this distance. The system also includes a control unit having a power supply, signal receiver circuitry for receiving positional signals from the sensor, a processor for providing interrogation zone modification instructions based upon the received positional signals, and signal transmission circuitry for transmitting signals, where the signals include the interrogation zone modification instructions. 
         [0013]    According to still another aspect, the present invention provides a sensor for use with a merchandise interrogation system. The system includes an antenna mounted to a movable door and a control unit having a processor for determining interrogation zone modification instructions. The sensor includes a sensing module for determining a distance that the door is moved in relation to a reference plane, and a transmitting module for transmitting positional signals representative of the distance that the door has moved in relation to the reference plane, where the positional signals are used by the control unit to determine interrogation zone modification instructions. 
         [0014]    Additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The aspects of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein: 
           [0016]      FIG. 1  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention; 
           [0017]      FIG. 2  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung inward at angle between 0 and 30 degrees; 
           [0018]      FIG. 3  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung inward at an angle between 30 and 45 degrees; 
           [0019]      FIG. 4  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung inward at an angle greater than 45 degrees; 
           [0020]      FIG. 5  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung outward at an angle between 0 and 30 degrees; 
           [0021]      FIG. 6  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung outward at an angle between 30 and 45 degrees; 
           [0022]      FIG. 7  is a diagram of a door-mounted antenna on a swinging door in accordance with the principles of the present invention, where the door is swung outward at an angle greater than 45 degrees; and 
           [0023]      FIG. 8  is a flowchart illustrating the process taken by an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The present invention advantageously provides a system that controls the interrogation zone created by an antenna mounted on a door, as the door moves throughout a different range of positions with respect to a reference plane. Referring now to the drawing figures in which like reference designators refer to like elements there is shown in  FIG. 1  a system constructed in accordance with the principles of the present invention and designated generally as “ 10 .” System  10  includes an antenna  12  mounted upon a movable door  14 . Antenna  12  can be an EAS antenna, an RF antenna or any other type of antenna that can transmit communication signals to a marker, where the marker can detect the incoming signals. Door  14  can be any type of movable door, i.e., a hinged door or a sliding door. In  FIG. 1  door  14  swings via hinges from a closed position, i.e., 0 degrees, to a fully-open position, i.e. 90 degrees. In the embodiment shown in  FIG. 1 , door  14  swings inward, i.e. into a store. However, the invention is not limited to a door that swings in this fashion, and later embodiments illustrate the system  10  used with a door that swings outward. Further, door  14  may swing in either direction and need not swing in the direction illustrated in  FIG. 1 . System  10  is also equally compatible with a door that slides. 
         [0025]    Antenna  12  may be configured as a transceiver antenna with an associated controller that provides control and switching to switch from transmitting to receiving functions at predetermined time intervals. Those skilled in the art will recognize that there may be a separate transmitting and receiving modules within antenna  12 . Antenna  12  emits electromagnetic signals covering a certain interrogation zone.  FIG. 1  shows the interior of a typical store or manufacturing facility that uses system  10  of the present invention. Within the interior of the manufacturing facility or retail establishment, various markers are placed on items or assets  16  to be protected within the interrogation zone. If the marker is not removed from the item  16  or deactivated prior to entering the interrogation zone, the electromagnetic field established by antenna  12  will cause a response from the marker. This response is received by the receiving module or the transceiver module of antenna  12 . 
         [0026]    Antenna  12  may be affixed or mounted to door  14  in a variety of ways, and the invention disclosed herein is not limited to a particular mounting means. For example, antenna  12  may be inserted within a drilled space on the top or side of door  14 , integrated within the door, or securely affixed to door  14  in any other manner. Door  14  swings from a closed position (0 degrees) through a range of open positions, relative to a reference plane  18 , e.g., the plane of the store wall. A position sensor  20  may be mounted on or near door  14 . Sensor  20  detects the movement of door  14  relative to reference plane  18 . Sensor  20  may be affixed or mounted to door  14 , or be positioned at a location proximate door  14 . Sensor  20  may be used in conjunction with another positional device, which may be placed on a non-movable object, such as the door frame. Either alone or in conjunction with a complementary positional device, sensor  20  detects movement of door  20  relative to plane  18 . Thus, as door  14  moves through a range of positions, sensor  20  detects this motion as well as the movement of door-mounted antenna  12 , which is affixed to and moves in accordance with door  14 . 
         [0027]    Sensor  20  may be any type of motion detector such as, but not limited to, an angle position sensor, a smart door hinge, or a switch or series of switches that transfers the position or angle of door  14  with respect to plane  18  to a controller  22 . In one embodiment, sensor  20  includes a sensing module for determining a distance that the door is moved in relation to a reference plane, and a transmitting module for transmitting positional signals representative of the distance that the door has moved in relation to the reference plane. 
         [0028]    Controller  22  may be mounted in any location capable of receiving positional signals from sensor  20  and exchanging communications signals with antenna  12 , and/or a store&#39;s alarm system, including on door  14  itself. Controller  22  includes a power supply, signal receiving circuitry, signal transmitting circuitry, and a processor. The controller&#39;s signal receiving circuitry receives positional information from sensor  20 , and the controller&#39;s processor compares the information with a table or database of rules, either stored in controller  22 , or at a remote location in communication with controller  22 . In other words, the processor can execute an algorithm that establishes a detection zone based on the position of door  14  as determined by sensor  20 . 
         [0029]    Based upon the processor&#39;s comparison of the present location of door  14  with the established rules, a correction signal containing interrogation zone modification instructions is transmitted, via the controller&#39;s transmitting circuitry, back to the receiving component in antenna  12 . In one embodiment, the correction signal may instruct antenna  12  to alter the magnitude of its magnetic field to account for the current position of door  14 . The correction signal may instruct antenna  12  to increase, decrease, or maintain the magnitude of the magnetic field, depending upon the location of door  14  as established by the stored rules. 
         [0030]      FIG. 2  illustrates a scenario where a door  14  has been opened inward, i.e., within the store. In this example, the door  14  is opened between a specified range of angles, namely 0 degrees to 30 degrees, with respect to reference plane  18 . In  FIG. 2 , controller  22  is now located in a different location within the store, to illustrate that controller  22  need not be in any particular location, provided it is still in communication, via either a wireless or a hard-wired connection, with sensor  20  and antenna  12 . In one embodiment, the processor of controller  22  can contain a table listing discrete ranges of door angles, each range corresponding to a particular set of instructions. Upon receipt of the current position of door  14 , the processor can determine, based upon the table, how much, if at all, to adjust the magnetic field of antenna  12 , and prepare instructions to accomplish this. Note that ranges of angles are for illustration only and that the system  10  of the present invention can be implemented with any suitable range or even with an algorithm that can adjust the interrogation zone on a continuous basis based upon the instant position of door  14 . 
         [0031]    For example, referring to  FIG. 2 , if door  14  is swung inward by 25 degrees, either by an entering or an exiting customer, this angle is detected by sensor  20  and a signal is transmitted to controller  22 , the signal including information indicating that the door  14  has been opened 25 degrees. Because this angle is within the 0 to 30 degree range, controller  22  may send a signal to antenna  12 , instructing it to increase or maintain (depending on the previous setting) the magnetic field to its maximum intensity. Taking into account the size of the store, and the proximity of marked merchandise and registers to the store exit, this might represent a scenario where full detection coverage is desired. 
         [0032]    Referring to  FIG. 3 , the door  14  has now been swung inward at an angle between 30 and 45 degrees, for example, 40 degrees. Once again, sensor  20  detects the current door angle, transmits a signal with this information to controller  22 . In this example, the processor of controller  22  determines that 45 degrees is within the next range of discrete angles, i.e., 30 to 45 degrees, and transmits a signal to antenna  12 , instructing it, in one example, to lower the magnitude of its magnetic field, in this case, to one half of its maximum value. This might represent a scenario in which the store does not want to create an over-range condition, where because of the inward motion of the door  14  and antenna  12 , an alarm may be triggered because a customer merely waiting on a check-out line has a marked item that has fallen within the “interrogation” zone of the antenna&#39;s magnetic field. By cutting the magnitude of the antenna&#39;s magnetic field, the interrogation zone is altered and customers may safely wait on a check-out line with a marked item without fear of an alarm being set when a customer opens the door to enter or exit the store, while the interrogation zone still captures marked active items being taken out of the store. 
         [0033]    In the example illustrated in  FIG. 4 , door  14  has now been swung inward at an angle of greater than 45 degrees. Because the position of door  14  at this new position may bring the alarm zone of antenna  12  within the signal range of still more marked items within the store, whether on the shelves, or with customers as they stand on a check-out line, it may be desirable to shut the magnetic field emitted by antenna  12  down completely. This may be accomplished in the same fashion as described above. Sensor  20  transmits its positional information to controller  22 , which determines an appropriate correction signal, and transmits a corresponding signal to antenna  12 , which adjusts its magnetic filed accordingly, in this case shutting it off completely, thus eliminating the interrogation zone. 
         [0034]    The above method of instructing antenna  12  to increase, maintain, or decrease the intensity of its magnetic field, is only one method of controlling the size of the interrogation zone utilizing system  10  of the present invention. There are a number of ways that the present invention can alter the scope of the interrogation zone. In one embodiment, as described above, upon receipt of a signal from controller  22  instructing it to increase or decrease the magnitude of its magnetic field, antenna  12  can adjust its transmitter power, thus increasing or decreasing the magnitude of the resulting magnetic field. In another embodiment, the sensitivity of the receiving module of antenna  12  is adjusted. In this embodiment, the intensity of the magnetic field is not altered, but the signals sent by an interrogated marker are received by the antenna&#39;s receiver module, the sensitivity of which has been adjusted. Depending upon how much it&#39;s sensitivity has been adjusted, the receiver module (or transceiver) of antenna  12  may ignore certain signals received from markers located at a certain location, or ignore all of the signals completely, thus, in effect, reducing or even eliminating the interrogation zone. 
         [0035]    In yet another embodiment, a combination of the previous two methods is used to obtain a desired interrogation zone. In still another embodiment, a store alarm, which would normally sound if a marked item falls within the magnetic field of antenna  12 , could be disengaged. Thus, for example, rather than transmitting instructions to antenna  12 , instructing it to increase the intensity of its magnetic field or adjusting its receiver module sensitivity, controller  22  sends a signal to the alarm device, which disengages the alarm. Thus, in the scenario illustrated in  FIG. 4 , i.e., when door  14  has been swung inward past 45 degrees, controller  22  may simply disengage the alarm device. The result is the same, e.g., an alarm will not sound when door  14  is opened past 45 degrees. 
         [0036]      FIGS. 2-4  illustrate the occurrence of an over-range condition. A store wants to avoid this scenario since it may trigger alarms in a situation where there is no actual alarm condition, i.e., when a marked item is properly on a shelf or with a customer on a checkout line.  FIGS. 5-7  illustrate steps taken by the present invention to prevent the occurrence of an under-range condition. In  FIG. 5 , door  14  is now being swung outward, away from the store. In this example, a door not opened (0 degrees with respect to reference plane  18 ) or swung outward up only up to 30 degrees may represent a situation where no interrogation zone is desired. Controller  22 , upon receipt of a positional signal from sensor  20 , would instruct antenna  12  to decrease or shut down completely the magnetic field, adjust the sensitivity of antenna  12  to basically ignore any signals received from interrogated markers, a combination of both, or deactivate an alarm. It should be noted that the degree ranges and corresponding controller actions provided in this disclosure are illustrative only, and the invention is not limited to any specific values. 
         [0037]    In  FIG. 6 , door  14  is now swung outward at a range of between 30 and 45 degrees with respect to the reference plane  18 . It may be desired at this door position to increase the interrogation zone to its maximum amount. Thus, upon receipt of the positional signal from sensor  20 , controller  22  can transmit a signal to antenna  12 , instructing it to increase or maintain (depending upon its previous state) the magnetic field to its maximum level, instructing it to adjust the receiver module sensitivity, or a combination of both. In the alternate, controller  22  can simply deactivate the store&#39;s alarm device. Should door  14  be swung even further in an outward direction, as shown in  FIG. 7 , it may be desired to maintain the magnetic field at a maximum intensity, reduce it by a certain amount, or shut it off completely. This may be accomplished in one of several ways described above. 
         [0038]      FIG. 8  is a flowchart illustrating the steps taken by the present invention in order to control the magnetic field radiated by a door-mounted antenna  12 . In step S 24 , sensor  20  detects the angle or door  14  with respect to reference plane  18 , and transmits this information to controller  22 , via step S 26 . Controller  22  then determines an interrogation zone correction amount, if any, by comparing the current angle of door  14  with a table of stored rules, via step S 28 . Controller  22  then transmits a signal, via step S 30 , to either antenna  12 , instructing it to alter its magnetic field or to adjust the sensitivity of its receiver module, or to an alarm device, deactivating the alarm device. If sensor  20  determines that the location of door  14  has changed, via step S 32 , sensor  20  detects the new door location via step S 24 , and repeats the above process. 
         [0039]    The present invention is equally adaptable to sliding doors rather than swinging doors. A sensor  20  may be used in the same way, i.e., sensor  20  detects door movement with respect to a reference point or plane  18 . Thus it is not needed to determine if door  14  is being swung outward or inward, but merely that is has moved in a particular direction. Therefore, in this embodiment, an angle position sensor is not needed. A linear position sensor  20  can be used to monitor and determine when door  14  has moved from its previous position. 
         [0040]    The present invention can also utilize a sensor  20  that determines the speed in which door  14  is moved. Thus, instead of or in addition to sensor  20  determining the relative position that door  14  has moved in relation to a reference point or plane  18 , a sensor  20  can be used to determine the speed of door motion. If, for example, door  14  opens very quickly, it may be the indication that someone is trying to exit the store without paying for marked merchandise. In this instance, the interrogation zone may be quickly increased to its maximum size and area. Various scenarios can be contemplated that utilize one or more sensors, each measuring a particular feature of the door, i.e. its relative position and/or its speed or movement. This information is transmitted to controller  20 , which determines if corrective action, with respect to the interrogation zone, needs to be taken. 
         [0041]    In another embodiment, the sensor  20  is replaced by an on/off switch. The switch can determine if, for example, door  14  has past a certain point, at which time it signals controller  22 , which, in turn, signals antenna  12  to deactivate. In still another embodiment, system  10  is only activated upon the opening (or closing) of door  14 . 
         [0042]    The present invention therefore advantageously provides a system and method which allows establishments to tailor the EAS or RFID system to its particular needs. Particularly, the invention takes into account the size of the store, and the proximity of marked merchandise and check-out counters in relation to exit doors, and creates a dynamic controlled system that can alter the interrogation zone as conditions change, i.e., as exit doors are opened and closed. 
         [0043]    The present invention can be realized in hardware, software, or a combination of hardware and software. An implementation of the method and system of the present invention can be realized in a centralized fashion in one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system, or other apparatus adapted for carrying out the methods described herein, is suited to perform the functions described herein. 
         [0044]    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.