HK1131688B - Wireless synchronized operation of pulsed eas systems - Google Patents

Description

Wireless synchronous operation of pulsed EAS system

Technical Field

The present invention relates generally to Electronic Article Surveillance (EAS) systems, and more particularly to systems and methods for providing synchronized operation in EAS systems.

Background

In acousto-magnetic or magnetomechanical Electronic Article Surveillance (EAS), a detection system may excite an EAS tag by transmitting an electromagnetic pulse at the resonant frequency of the tag. When a tag is placed in the electromagnetic field generated by the transmitted pulse, the tag begins to resonate at an acousto-magnetic or magnetomechanical response frequency that is detectable by a receiver in the detection system. The detection unit may then provide some type of signal, e.g., an alarm signal, indicating the detection of a response from the EAS tag.

In an EAS system, the transmitter pulse signal typically does not end abruptly, but decays exponentially, because the transmitter circuit resonates. If the transmissions from nearby units are not time synchronized, false detections may occur because the units may transmit and receive at the same frequency. These false detections can result in false alarms.

It is known to use multiple detection units, for example multiple detection bases (pedestal), to monitor a larger area such as a retail outlet. Each base typically includes multiple antennas that are controllable from a single multi-channel controller. The controller coordinates and synchronizes the antenna operation of each detection base.

It is known to use a separate controller at each detection unit. In this configuration, communication between the controllers is provided to coordinate the operation of each unit, including synchronizing antenna operation. In these multi-controller systems, it is known to use wired synchronization, in which communication signals are transmitted between the controllers over one or more wired connections. The installation and connection of wiring between the detection units can be complex and time consuming. For example, if an existing floor needs to be excavated in order to install the wiring, this process increases the time and expense of installation. Furthermore, the likelihood of installation problems increases, for example, due to the complexity of installation or the use of special tools.

It is known to provide wireless synchronization to communicate with other controllers regarding other detection units. In these systems, these synchronous communications are transmitted outside of the normal transmission window. Specifically, transmitting the synchronization signal in the receive window corrupts the received signal over large distances. In addition, a high sensitivity receiver is used to detect the synchronization signal. This high sensitivity may result in controllers at different locations (e.g., different outlets) detecting a synchronization signal intended for another location. Thus, isolation is a problem that can lead to erroneous communication and control problems.

Disclosure of Invention

In one embodiment, a method of communicating information between a plurality of detectors in a plurality of Electronic Article Surveillance (EAS) systems is provided. The method includes wirelessly communicating between a plurality of controllers connected to a plurality of detectors of the plurality of EAS systems and receiving wireless communications from at least some other of the plurality of controllers using a communication receiver of each controller. The communication receiver may be separate from the tag detection receiver.

In another embodiment, a method for controlling transmissions between a plurality of Electronic Article Surveillance (EAS) systems is provided. The method includes transmitting an excitation signal to an interrogation zone during a transmission phase, receiving signals from excited EAS tags in the interrogation zone during the transmission phase, and determining a noise average during a noise averaging phase in which no transmission is occurring. The method may further include processing the received signals during a detection processing phase in which no transmission or reception occurs, and wirelessly communicating information between the plurality of detectors of the plurality of EAS systems during a communication phase.

In yet another embodiment, a system having a plurality of Electronic Article Surveillance (EAS) systems is provided. The system includes a plurality of detectors and a plurality of controllers, each controller connected to at least one of the plurality of detectors and defining the plurality of EAS systems. The controller may have a communication receiver. The system may also include a communication antenna connected to the communication receiver and configured to receive wireless communication signals from other controllers.

Drawings

For a better understanding of the various embodiments of the present invention, reference should be made to the following detailed description, read in conjunction with the following drawings, wherein like numerals represent like parts. FIG. 1 is a block diagram of a portion of an Electronic Article Surveillance (EAS) system in connection with which various embodiments of the present invention may be implemented. Fig. 2 is a schematic diagram of a detector arrangement for the EAS system of fig. 1, with a controller constructed in accordance with an embodiment of the invention. FIG. 3 is a block diagram illustrating a controller constructed in accordance with an embodiment of the invention. FIG. 4 is a timing diagram illustrating a multi-stage processing cycle according to an embodiment of the invention. Fig. 5 is a schematic diagram of a phase modulation scheme for encoding message information in accordance with an embodiment of the present invention. Fig. 6 is a flow diagram of a method for controlling transmissions of a plurality of detectors of an EAS system in accordance with an embodiment of the invention. Fig. 7 is a block diagram illustrating multiple detectors for frequency division multiplexing and frequency reuse according to an embodiment of the present invention.

Detailed Description

Various embodiments of the present invention provide methods and systems for synchronized operation, particularly synchronized operation such as communication and/or transmission between a plurality of Electronic Article Surveillance (EAS) systems, each typically having a controller and at least one coil. A typical EAS system will first be described followed by various embodiments of the invention for controlling and configuring the EAS system, and in particular for synchronized operation in the EAS system.

Fig. 1 illustrates an embodiment of a system having one or more EAS systems 20. The EAS system 20 may include a plurality of detector units 22. Each detector unit 22 may be configured to monitor an area 24 (e.g., within a range of the detector unit 22) for detection of EAS tags 26 having predetermined characteristics (e.g., resonant frequency) as is known. The coverage of each area 24 may overlap with adjacent areas 24. Further, the detector units 22 may be configured to communicate information therebetween using any suitable communication link. In one embodiment, communication between detector units 22 is provided through a wireless communication link 28. It should be noted that any detector unit 22 may be in communication with any or all of the other detector units 22.

The detector unit 22 may be of any type desired or required, for example, a sensormatic detector available from Tyco Fire & Security of Boca Raton, Florida. By way of example, FIG. 2 illustrates a detector unit 22 of an EAS system 20, which may be controlled and synchronized by various embodiments of the present invention described herein. In particular, each detector unit 22 may include a detector portion 30 defining a detection zone 32, such as between different detector portions, for detecting an EAS tag 34 in the detection zone 32. The detector portion 30 of each detector unit 22 in one embodiment may include a plurality of antenna pedestals, such as antenna pedestal 36 and antenna pedestal 38. Each of the antenna pedestals 36 and 38 may be connected to a controller 40 to control transmissions from the antenna pedestals 36 and 38. Each controller 40 is also configured to communicate with the controllers 40 of the other antenna pedestals. In other embodiments, a single controller 40 may be connected to multiple pedestals 36 or 38 to define one EAS system 20 (as shown in FIG. 1).

In particular, each controller 40 may be configured to control (e.g., synchronize) transmissions from the antenna pedestals 36 and 38 and receptions at the antenna pedestals 36 and 38, such as transmitting an excitation signal to the EAS tag 34 and receiving a signal generated by the EAS tag 34. In operation, for example, a visual or audible alarm may be provided when a signal is received in the detection zone 32 from an EAS tag 34 that has not been deactivated by a deactivator unit (not shown).

It should be noted that when reference is made herein to the EAS system 20, it is generally meant to refer to a system having a controller 40 and at least one coil, for example, within the antenna pedestals 36 or 38. However, various embodiments may be implemented in accordance with EAS systems 20 having different configurations. For example, various embodiments may provide communication or transmission between EAS systems 20, each EAS system 20 having a single controller 40 connected to multiple pedestals 36 or 38. Further, the controller 40 may be implemented in a power pack or a single electronic unit.

Furthermore, detector unit 22 represents many detector systems and is provided as an example only. For example, the controller 40 may be located in or adjacent to each antenna base. Additional antennas may also be provided that receive signals from only certain EAS tags 34.

Fig. 3 shows a block diagram representing a controller that may be implemented in the controller 40. The controller 40 may generally include a power amplifier/transmitter unit 42 and a tag detection receiver, such as a detection analog front end unit 44, which together define an EAS tag monitoring portion that controls the transmission and reception of signals by an antenna, which in one embodiment is an interrogation antenna 46. The power amplifier/transmitter unit 42 and the detection analog front end unit 44 may be provided in any known manner to control transmission and reception at the interrogation antenna 46 to monitor EAS tags in the EAS system 20 (shown in fig. 1). It should be noted that interrogation antenna 46 may be provided as part of pedestals 36 and 38 (shown in FIG. 2).

The controller 40 may also include a wireless communication receiver, e.g., a communication analog front end unit 47, which is connected to a communication antenna 48 to provide communication between different controllers 40 in one or more EAS systems 20 (shown in fig. 1), e.g., between controllers 40 connected to different pedestals, as described in more detail below. In one embodiment, the communication antenna 48 may be a small, single loop antenna configured to receive communications from other controllers 40 and may be used to synchronize the operation of multiple detector units 22 (as shown in FIG. 1) and/or multiple EAS systems 20. The communication analog front end unit 47 may be configured to provide low gain operation (e.g., gain for communication in the range of about 25 feet to about 35 feet) and bandpass filtering based on the communication frequency desired or required by the controller 40. The gain of the communication analog front end unit 47 is configured such that the communication antenna 48 has only near field sensitivity. For example, the communication analog front end unit 47 may be configured such that communication is only provided between controllers 40 within a portion of the EAS system 20, between adjacent EAS systems 20, within a predetermined area (e.g., between controllers at a pedestal at an exit of a retail store), and so forth. It should be noted that the interrogation antenna 46 may be used to provide transmissions from one controller 40 to another controller 40 and a separate communication antenna 48 may be used to receive the transmitted signals.

The controller 40 may also include a processor 50 connected to each of the power amplifier/transmitter 42, the detection analog front end 44, and the communication analog front end unit 47. The processor 50 may be configured to control communication between the controllers 40. In particular, as shown in the timing diagram of fig. 4, the controllers 40 are configured to provide a multi-phase communication and/or processing cycle, e.g., one 4-phase communication/processing cycle 60, which allows communication between different controllers 40. It should be noted that the length or duration of each phase and/or each transmission window may be different. More specifically, the first stage 62 is a transmission stage in which a high power, unmodulated transmission signal is transmitted in an interrogation zone, such as the detection zone 32 (shown in fig. 2), to which a transmission window 63 is transmitted. For example, a signal is transmitted at a frequency or range of frequencies configured to excite any EAS tag located in the interrogation zone. As is known, this transmission may include the use of a power amplifier/transmitter 42 and an interrogation antenna 46 (both shown in fig. 3) to transmit electromagnetic pulses at the resonant frequency of the EAS tag to be detected. In the first stage 62, signals from the energized EAS tags may also be received.

The second stage 64 is a noise averaging stage in which no transmission occurs. This stage is used to provide a noise level to compare any received signals, for example, from an energized EAS tag. The third stage 66 is a detection processing stage in which no transmission or reception occurs. The third stage 66 is used in a detection process performed by the processor 50 (shown in fig. 3) and the results determine messages to be transmitted from the controller 40 to other controllers 40, such as other pedestals located at the exit of a retail store, which other controllers 40 may be located in different EAS systems 20. The result of this third stage 66 may also be the detection of an EAS tag, in which case an appropriate alarm (e.g., an audible or visual alarm) would be generated.

The fourth stage 68 is a communication stage in which low power modulated transmission signals (e.g., communication pulses) are transmitted from the controller 40 to other controllers 40, such as adjacent or nearby controllers 40, during a transmission window 69. Adjacent or nearby controllers 40 may be located in different EAS systems 20. The low power modulated transmission signal may be transmitted using an interrogation antenna 46 (shown in figure 3). While transmitting the communication signal, the controller 40 simultaneously monitors a dedicated low-sensitivity reception channel for communication signals from other controllers 40. A communication analog front end unit 47 (shown in fig. 3) may be configured to provide the receive channel. After the communication signals are communicated and received by the other controllers 40, the processor 50 (shown in FIG. 3) processes the received signals. For example, the communication signal may generally define a message signal and the processor 50 may demodulate the message signal from the other controller 40 to determine further operations to be performed. For example, based on the local state and the state of one or more neighboring controllers 40 as determined by the communication signal, the controller 40 may determine the next operation to be performed at the next first stage 62 (which is the next transmission stage). It should be noted that different communication phases and timings are provided as desired or needed, for example, based on the type of EAS system or detector.

Using the phase modulation scheme 70 shown in fig. 5, different messages may be communicated between the controllers 40 via the communication signal during the communication phase 68. The phase modulation scheme 70 may be changed or modified based on, for example, the type of EAS system or the type of detector. The phase modulation scheme 70 may be used with, for example, an EAS detector unit from Tyco Fire & Security of Boca Raton, Florida. In particular, assuming that N bits are transmitted on each communication burst, a 1.6 millisecond (msec) communication burst may be divided into N +1 segments 72, with the first segment configured to train a receiver, such as the communication analog front end unit 47, during the signal phase. Subsequent segments 72 may be inverted to indicate a "1" bit or not inverted to indicate a "0" bit. Using phase modulation and/or amplitude and frequency modulation, different signals communicating different information may be provided. For example, a phase modulation scheme may be used in which up to 8 bits per pulse may be transmitted. Using modulation scheme 70 or other modulation schemes, various messages may be communicated between controllers 40 (as shown in fig. 3), including, for example, the following:

a "Tx Off Check" message to request that the neighbor detector block the interrogation pulse in the next transmission phase.

An "authentication" message to indicate that the transmission sequence should remain in the same state as the previous transmission phase when authenticating the tag signal. This message can be used to repeat the signal at the same frequency and antenna phase to determine if a neighboring detector should be turned off because it is exciting a tag located in a different interrogation zone.

An "area detect" message to determine which antenna "sees" the stronger EAS tag signal.

A "synchronization" message to determine the timing of transmissions in a transmission phase for synchronizing the transmissions. It should be noted that other messages may be provided to control operation, for example, to control transmissions from multiple detectors 22 (as shown in fig. 1). It should also be noted that other modulation schemes for communicating message information may be provided.

Fig. 6 illustrates a method 80 for controlling the operation of a plurality of EAS systems (e.g., transmission of a plurality of detectors of an EAS system). More specifically, at step 82, communication messages are communicated (e.g., transmitted and received) between controllers associated with detectors of one or more EAS systems. Which may include transmitting a low power modulated message signal (allowing higher data rate communications) with transmission pulses in a transmission window of a communication phase (as shown in fig. 4). The message signals (near field, full duplex signals) are communicated to a local controller, e.g., a controller in a predetermined or predefined area of one or more EAS systems. As described in more detail above, during this communication phase, the controller also receives message signals from other controllers, e.g., via a dedicated low-sensitivity receive channel.

The message signal is then processed at step 84, which may include demodulating the signal. In one embodiment, for example, the phase of the signal between time periods (as shown in FIG. 5) is compared to determine if the phase is inverted or if an inversion pattern is identified. Control information or messages (as described above) may be encoded into the phase change, which is determined in this stage of processing. In addition, the current state of the detector may also be determined. Based on the processed received message signal and/or the state of the detector, it is determined whether an action is required at step 86. If no action is required, for example, if the detector is in a hold state, the method 80 returns to the transmit and receive messages of step 82, which may include transmitting a message including the current state of the detector. If operation is required, for example, if a message is received indicating that the next transmission signal needs to be blocked, the detector is controlled accordingly (e.g., the next transmission pulse is blocked) at step 88. Thereafter, the method 80 returns to the transmit and receive messages of step 82, which may include transmitting a message including the current state or most recent operation of the detector (e.g., blocking transmission of pulses).

It should be noted that when multiple detectors 22 defining one or more EAS systems 20 are provided in an area or location (e.g., a retail store exit), frequency division multiplexing may be used to separate the signals of the controller, as shown in fig. 7. In addition, frequency reuse may be provided at controllers at different locations (e.g., different exits) of the EAS system. A plurality of pedestals 90 and 92 are provided at each of a first location 94 (e.g., a first outlet) and a second location 96 (e.g., a second outlet), respectively. For example, multiple EAS pedestals from TycoFire & Security of Boca Raton, Florida may be provided with 5 different available frequency channels (e.g., 48kHz, 53kHz, 58kHz, 63kHz, and 68 kHz). Each pedestal 90 and 92 in each of the first and second locations 94 and 96 may be configured to transmit on a different available frequency, with each of the first and second locations 94 and 96 using frequency reuse.

As such, various embodiments of the present invention provide for controlling, and more specifically synchronizing, the operation of detection units in multiple EAS systems. For example, the synchronization operation may be used to determine whether an EAS tag being detected is located between two detectors or whether a signal from one detector interferes with another detector. A separate communication antenna is provided that is configured with a dedicated low-sensitivity receive channel. Thereby providing low power, modulated communication transmissions between controllers connected to each of a plurality of detectors of the EAS system, providing higher data rate communications. The communication of the message is performed during a communication burst window of the communication phase. Near field sensitivity and frequency division multiplexing allow full duplex communication.

Various embodiments or components, such as the controller 40 or other components, may be implemented as part of a computer system, which may be separate or integrated with the EAS system. The computer system may comprise a computer, an input device, a display unit and an interface, for example for accessing the internet. The computer may include a microprocessor. The microprocessor may be connected to a communication bus. The computer may also include a memory. The memory may include Random Access Memory (RAM) and Read Only Memory (ROM). The computer system may also include a storage device, which may be a hard disk drive or a removable storage drive such as a floppy disk drive, optical disk drive, and the like. The storage device may also be other similar means for loading computer programs or other instructions into the computer system.

As used herein, the term "computer" may include any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Circuits (RISC), Application Specific Integrated Circuits (ASICs), logic circuits, digital signal processors, and any other circuit or processor capable of executing the functions described herein. The above examples are not intended to limit in any way the definition and/or meaning of the term "computer".

The computer system executes a set of instructions stored in one or more storage elements to process input data. The storage element may also store data or other desired or required information. The storage element may be in the form of an information source or a physical memory element located in the processing machine.

The set of instructions may include various commands that instruct the computer as a processing machine to perform specific operations such as the methods and processes of the various embodiments of the invention. The set of instructions may be in the form of a software program. The software may be in various forms, such as system software or application software. Further, the software may be in the form of a collection of separate programs, a program module within a larger program or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by a processing machine may correspond to a user command, or to the result of a previous processing, or to a request made by another processing machine.

As used herein, the terms "software" and "firmware" are interchangeable, and include any computer program stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are examples only, and are thus not limiting as to the types of memory usable for storage of a computer program.

It will be understood that various changes and modifications may be made to the various embodiments of the invention without departing from the scope thereof. It is also to be understood that the scope of the various embodiments of the invention, when read in light of the above disclosure, should not be construed as limited to the particular embodiments disclosed herein, but rather construed according to the below claims.

Claims (17)

1. A method for synchronizing operation of a plurality of detectors in an Electronic Article Surveillance (EAS) system, the method comprising:

providing a plurality of controllers connected to detectors of at least one EAS system, the detectors configured to monitor an associated interrogation zone of an EAS tag, the controllers configured to cause the detectors to transmit EAS excitation signals to the interrogation zone during a transmission phase and to receive signals from the excited EAS tag;

providing a wireless communication channel between controllers; and

transmitting a message between the controllers over the wireless communication channel in a communication phase separate from the transmission phase, the controller using the message to control transmission of the EAS excitation signal.

2. The method of claim 1, further comprising configuring an antenna to receive the message separately from a signal from the energized EAS tag over a wireless communication channel.

3. The method of claim 2, wherein the antenna comprises a single loop antenna.

4. The method according to claim 1, wherein said transmitting further comprises modulating said message with at least one of a phase, an amplitude, and a frequency, said EAS excitation signal being unmodulated.

5. The method of claim 1, further comprising configuring the wireless communication channel to have near field sensitivity.

6. The method of claim 1, wherein the method further comprises a noise averaging stage and a detection processing stage, the communication stage being separate from the transmission stage, the noise averaging stage and the detection processing stage.

7. The method of claim 1, wherein the messages comprise zone detection messages that are used by at least one of the controllers to determine which detector receives a stronger signal from an energized EAS tag.

8. The method of claim 1, further comprising connecting each of the plurality of controllers to a different one of the plurality of detectors.

9. The method of claim 1, wherein the plurality of detectors are configured as base units.

10. The method of claim 6, wherein the noise level is provided during a noise averaging stage.

11. The method of claim 1, wherein the transmitting comprises transmitting a communication message from a first controller while the first controller simultaneously monitors a low-sensitivity receive channel for communication messages from at least one other controller.

12. A method for controlling transmissions between a plurality of electronic article surveillance, EAS, systems, the EAS systems including a detector and a controller, the method comprising:

transmitting an excitation signal from a detector of the first EAS system to an interrogation zone during a transmission phase of the first EAS system;

receiving, at a detector, a signal from an energized EAS tag in the interrogation zone;

determining noise information during a noise detection phase of the first EAS system, wherein the excitation signal does not occur during the noise detection phase, the noise information being indicative of a level of noise experienced at a detector of the first EAS system;

processing the received signal in a detection processing stage; and

wirelessly communicating messages between controllers of the plurality of EAS systems during a communication phase of a first EAS system,

wherein the communication phase, the transmission phase, the noise detection phase and the detection processing phase are separated from each other.

13. The method of claim 12, wherein said wirelessly communicating messages comprises transmitting one of phase modulation messages, amplitude modulation messages, and frequency modulation messages.

14. The method according to claim 12, wherein the EAS system includes an interrogation antenna and a communication antenna, the wirelessly communicating messages including transmitting messages using the interrogation antenna during the communication phase and transmitting EAS excitation signals using the interrogation antenna during the transmission phase and receiving the wirelessly transmitted messages using the communication antenna during the communication phase.

15. An Electronic Article Surveillance (EAS) system, the system comprising:

a plurality of detectors configured to monitor an associated interrogation zone of an EAS tag, the detectors having a first antenna pedestal and a second antenna pedestal;

a plurality of controllers connected to the respective detectors, each controller configured to control the first and second antenna pedestals to transmit an EAS excitation signal to the interrogation zone during a transmission phase and configured to receive signals generated by an EAS tag; and

a communication channel configured to communicate wireless communication messages between controllers in a communication phase separate from a transmission phase, the controllers using the messages to control transmission of EAS excitation signals.

16. The system according to claim 15, further comprising an interrogation antenna for transmitting said EAS excitation signal and a communication antenna for transmitting said message, wherein said EAS excitation signal and said message are transmitted separately from each other.

17. The system of claim 15, wherein the controller is configured to modulate the message as a wireless communication signal in one of phase, amplitude, and frequency.