HK1123116B - Eas system providing synchronized transmission - Google Patents

Description

Electronic article surveillance system providing synchronized transmissions

Technical Field

The present invention relates generally to Electronic Article Surveillance (EAS) systems and, more particularly, to a system and method for synchronizing transmissions in an EAS system.

Background

In an acousto-magnetic or magnetomechanical Electronic Article Surveillance (EAS) system, both detection and deactivation units may be provided. The two units typically excite the EAS tag by transmitting an electromagnetic pulse at its resonant frequency. When the tag is present in the electromagnetic field created by the transmitted pulse and has not been deactivated, the tag begins to resonate at an acousto-magnetic or magnetomechanical response frequency that is detectable by the receivers in the two detection units. The detection unit may then provide some type of signal, such as an alarm signal, to indicate detection of a response from the EAS tag. The deactivation unit also typically sends a deactivation signal to deactivate the EAS tag so that the EAS tag will not resonate at the acousto-magnetic, magnetomechanical or electromagnetic response frequency when present in the electromagnetic field of the detection unit.

In EAS systems, the transmitter pulse signal typically does not end abruptly, but rather decays exponentially due to transmitter circuit resonance. If the transmissions from nearby units are not synchronized, false detections can occur because all units transmit and receive at the same frequency. These false detections may result in false alarms and/or false deactivations.

To synchronize transmissions from the detection and deactivation units of the EAS system, a manual synchronization process is typically performed. In particular, the field service personnel synchronize each unit using a configuration program and a phasing tool that includes two loop antennas and an oscilloscope. Synchronization is provided by varying the delay time of a cell from the AC zero crossing reference of the cell to transmission. This process is repeated, for example, in a retail store for each deactivation and detection unit.

However, since the AC power wiring to each cell may be different, for example, depending on how the power is wired (e.g., how the power outlet is wired), the phase may be shifted by 120 degrees, and the AC zero crossings may be different. This can result in incorrect synchronization of the units because the individual zero crossings are out of phase. In addition, the isolation transformer of each cell also affects the delay required for synchronization with other cells. Thus, the manual synchronization process is not only time consuming and susceptible to human error, such as when reading an oscilloscope, but the reference used to synchronize the units may be different due to power wiring differences. Out of phase synchronization will occur.

Other known systems or processes for synchronizing units within an EAS system provide for communicating the precise time of transmission of each unit or for synchronizing units using a reference signal transmitted by a broadcast transmitter. However, these processes often do not adequately synchronize the units and are costly to implement because of internal delays and other transmission delays within the units. Furthermore, providing a reference signal from a broadcast transmitter requires reliable reception of the signal 24 hours a day from a selected FM or TV broadcaster. This increases the complexity and cost of the system.

Units within an EAS system may also be synchronized by periodically shutting down transmissions and then listening for other EAS transmitters from which the delay between the received signal and the AC zero crossing of the shut down unit is determined. However, this process may not satisfactorily synchronize the deactivator and detector units because of the large differences in transmit power and antenna size of these different types of units.

Disclosure of Invention

The method may include determining a transmission timing difference between a plurality of units of an Electronic Article Surveillance (EAS) system using a communication link of the EAS system, and synchronizing transmissions of each unit according to the transmission timing difference.

In another embodiment, a method for calibrating an Electronic Article Surveillance (EAS) system to synchronize transmissions is provided. The method may include selecting one of a plurality of units of the EAS system as a master synchronization unit and communicating a broadcast signal to the plurality of units based on a synchronization event of the master synchronization unit. The method may also include determining, for each unit, a time period from receipt of the broadcast signal to the next transmission by the unit, and determining a difference between the time periods of the master synchronization unit and each of the other units. The method may also include establishing a delay for each unit based on the determined difference to synchronize transmissions of each unit.

In another embodiment, an Electronic Article Surveillance (EAS) system is provided that may include a plurality of detector units and at least one of a plurality of deactivator units connected by a communication link. The EAS system may also include a system controller configured to (i) determine a transmit timing difference between the plurality of units using the communication link; and (ii) synchronizing the transmission of each unit according to the transmission timing difference.

Drawings

For a better understanding of various embodiments of the present invention, reference should be made to the following detailed description which should be read in conjunction with the accompanying drawings wherein like numerals represent like parts.

FIG. 1 is a block diagram of an embodiment of an Electronic Article Surveillance (EAS) system in which various embodiments of the present invention may be implemented.

Fig. 2 is a diagram of a detector of the EAS system of fig. 1.

FIG. 3 is a diagram of a deactivator of the EAS system of FIG. 1.

Fig. 4 is a flow diagram of a method for synchronizing transmissions in an EAS system in accordance with an embodiment of the invention.

Fig. 5 is a flow chart of a unit synchronization detection process according to an embodiment of the present invention.

FIG. 6 is a diagram of a user interface for controlling synchronization of a detector and deactivation unit of an EAS system according to an embodiment of the present invention.

FIG. 7 is an embodiment of a user interface for controlling synchronization of a detector and deactivation unit of an EAS system according to an embodiment of the present invention after synchronizing one unit.

Detailed Description

Various embodiments of the present invention provide methods and systems for synchronizing transmissions in an Electronic Article Surveillance (EAS) system. A typical EAS system will first be described followed by a description of various embodiments of the invention for controlling and configuring the EAS system and more particularly synchronizing transmissions in the EAS system.

An embodiment of an EAS system 20 is shown in fig. 1. The EAS system 10 may include an EAS system controller 22 coupled to a plurality of detector units 24 and a plurality of deactivator units 26. The EAS system controller 22 controls the transmission and reception of the detector units 24 and deactivator units 26. Communication between the EAS system controller 22 and the detector units 24 and deactivator units 26 may be provided by any suitable communication link, which in one embodiment is a serial communication link.

The EAS system controller 22 controls transmissions from the detector units 24 and receptions received by the detector units 24 as is known to detect EAS tags within a certain range of the detector units 24. The EAS system controller 22 also controls transmissions from the deactivator unit 26 and receptions received by the deactivator unit 26, as is known to deactivate EAS tags that are within a certain range of the deactivator unit 26 and have predetermined characteristics.

The detector unit 24 and deactivator unit 26 may be of any type desired or needed, for example, Tyco Fire from Boca Raton, Florida&Obtained from Security corporationFor example, FIG. 2 is an example of a detector unit 24 of an EAS system 10, which may be controlled and synchronized by various embodiments of the present invention described herein, in particular, the detector unit 24 may include a detector portion 30 that defines a detection region 32 for detecting an EAS tag 34 located within the detection region 32. in one embodiment, the detector portion 30 includes a first antenna pedestal 36 and a second antenna pedestal 38. the antenna pedestals 36 and 38 may be connected to a control unit 40, the control unit 40 including a transmitter 42 and a receiver 44. within the control unit 40, a controller 46 is configured to provide communication with external devices, such as the EAS system controller 22 (as shown in FIG. 1).

In addition, the controller 46 may be configured to control the transmission from the transmitter 42 and the reception at the receiver 44 such that the antenna pedestals 36 and 38 may be used to both transmit signals to the EAS tag 34 and to receive signals generated by the EAS tag 34. In operation, for example, a visual and/or audible alarm may be provided when a signal is received from an EAS tag 34 within the detection region 32 that has not been deactivated by the deactivator unit 26.

The detector unit 24 is representative of many detector systems and is provided as an example only. For example, in an alternative embodiment, the control unit 40 may be located within one of the antenna bases. In another embodiment, an additional antenna that receives only frequencies from the EAS tags 34 may be utilized as part of the EAS system 20. Further, a single control unit 40, either within the base or separately provided, may be configured to control multiple sets of antenna bases.

As another example, FIG. 3 is an illustration of a deactivator unit 26 of the EAS system 10, which may be controlled and synchronized by the various embodiments of the present invention described herein. In particular, the deactivator unit 26 may include a deactivator portion 50 that defines a deactivation zone 52 for deactivating EAS tags within the deactivation zone 52. In one embodiment, the deactivator portion 50 may be a separate unit configured to be connected to, for example, a barcode scanner unit 54. In another embodiment, the deactivator portion 50 may be integrated with the barcode scanner unit 54. The barcode scanner unit 54 may also include a scanning portion 56 for scanning items having readable barcodes. The deactivator portion 50 may be connected to a control unit 58 that includes a transmitter 60 and a receiver 62. In the control unit 58, the controller 64 is configured to provide communication with external devices, such as the EAS system controller 22 (shown in fig. 1).

Additionally, the controller 64 may be configured to control the transmission from the transmitter 60 and the reception at the receiver 62 such that signals may be transmitted to and received from an EAS tag, which may be provided, for example, as part of an article tag or packaging, using the deactivator portion 50, which may include one or more antennas (not shown). In operation, for example, upon receiving a signal from an EAS tag having a predetermined characteristic within the deactivation zone 52, the transmitter 60 may transmit a deactivation signal as is known to deactivate the EAS tag.

Deactivator unit 62 is representative of many deactivator systems and is provided by way of example only. For example, in an alternative embodiment, the control unit 58 may be located within the barcode scanner unit 54. In another embodiment, deactivator portion 50 may be configured having a different shape and orientation, such as a transverse direction as opposed to the longitudinal direction shown in FIG. 3.

Various embodiments of the present invention provide for synchronizing transmissions in an EAS system and, more particularly, synchronizing transmissions from detector units 24 and deactivator units 26. It should be noted that each detector unit 24 and deactivator unit 26 may be assigned a unique address, and more specifically, each control unit associated therewith may be assigned, for example, a unique serial number. Furthermore, the detector unit 24 and the deactivator unit 26 may include, for example, a processor and/or memory provided as part of the controllers of these units for storing information.

FIG. 4 is a flow chart of a method 70 for synchronizing transmissions in an EAS system, in particular, at step 72, the detector units and deactivator units of the EAS system may be identified, for example, by a unique address corresponding to each unit, this identification process may include accessing a database of stored addresses or polling the units over multiple communication channels to determine the connected detector and deactivator units, for example, in a retail environment, such as a grocery store, multiple deactivator units may be provided at checkout and multiple detection units may be provided at the entrance/exit of the store, communication between the units and a controller, such as the EAS system controller 22 (shown in FIG. 1) may be provided by a serial communication link that determines the network architecture, for example, a RS-232 communication link may be used to provide network communications, thus, each detector and deactivator unit may be provided with a unique network address that is addressable via a port, such as an RS-232 service port of an EAS system.

It should be noted that any known communication and control program and desired or required user interface may be used to provide for communication and configuration of the elements within the network. For example, in one embodiment, communication and configuration functionality may be provided by a configurator interface available from Tyco Fire & Security, Inc. of Boca Raton, Florida.

After the units are identified at step 72, one of the plurality of detector and deactivator units may be selected as the master synchronization unit at step 74. For example, the user may select one of the identified units as the master synchronization unit via a user interface. After the primary synchronization unit is selected, a broadcast message may be delivered to all identified units at step 76. The broadcast message is delivered based on a synchronization event of the master synchronization unit.

Upon receiving the broadcast message, each detection and deactivator unit may initiate a unit synchronization detection process 100 as shown in FIG. 5. This process 100, which will be described in more detail later, causes each unit to generate timing information, such as a count between the time the unit receives the broadcast message and the next transmission of the unit. At step 78, timing information from each unit initiated by the broadcast message is received. The master synchronization unit may also generate timing information. The difference between the timing information of each unit and the timing information of the master synchronization unit may then be determined at step 80. For example, in one embodiment, this may include determining a difference in the count value of each unit as compared to the master synchronization unit.

Based on the difference, the delay of each cell may be determined at step 82. For example, the difference value calculated for each cell may be converted into a delay value corresponding to the calculated count value difference. The delay value for each element may then be passed to the corresponding element at step 84 to delay each transmission from that element, e.g., from the master clock. In this way, each unit can now be synchronized with respect to all other units, in particular, each periodic transmission from each of these units.

It should be noted that the method 70 may be performed iteratively until a minimum timing difference between the cells is reached. This iterative process may be performed, for example, for each unit until the timing difference is less than a predetermined value, e.g., so that the transmission will not interfere with reception. For example, the predetermined value may be 50 microseconds.

Referring to fig. 5, upon receiving the broadcast message, each detection and deactivator unit may initiate a unit synchronization detection process 100. Specifically, upon identifying a broadcast message from a master synchronization unit at step 102, a counter within the unit may be started at step 104. For example, a count flag may be set independently within each cell. It should be noted that each count of the counter represents a time period and may be the same for each cell. In an alternative embodiment, a timer may be started. The number of counts between receiving the broadcast message and the next transmission (or zero crossing) of the unit may be measured at step 106.

Count information defining the timing information for each cell may then be stored at step 108, for example in Random Access Memory (RAM) for each cell. At step 110, timing information, which in this embodiment is a count value, may be communicated to the master synchronization unit based on a request from the master synchronization unit. Thereafter, each unit may receive a delay value as described above for delaying the transmission of the unit according to the timing information, step 112. For example, a delay value may be passed to the control unit of each detector and deactivator unit for delaying each transmission from the transmitter of those units. It should be noted that the delay for each cell may be different.

Various embodiments of the present invention may also include a user interface for controlling the synchronization of the units of the EAS system as described above, for example, as shown in FIGS. 6 and 7, a user interface 120 having a control portion 122 and an analysis portion 124 may be provided, the control portion 122 may include a network interface control panel 126 for controlling the units connected to a particular EAS network and controlling the synchronization thereof The identified cell is displayed at 140.

The transmission timing of one or more selected cells is displayed on the analysis section 124, and the analysis section 124 is configured as an oscilloscope in the present embodiment. It should be noted that the transmission timings of these units may not be synchronized as shown. After the master synchronization unit is selected, a synchronization process, such as that shown and described with reference to fig. 4 and 5, may be initiated. For example, by activating (e.g., using a mouse press) the polling synchronization link selection component 142, broadcast message transmissions may be delivered to each unit using the various embodiments described herein. Thereafter, after determining the delay for each cell using the various embodiments described herein, the synchronization selection component 138 is activated and the first cell (cell 2 in this example) in the list of cells displayed in the cell identification portion 140 may be synchronized with the master synchronization cell (cell 5 in this example). This includes sending a delay value to the unit as described in more detail herein.

After the first unit has synchronized with the master synchronization unit, the synchronization process may continue for the other units in the list, as shown by analysis portion 124 in FIG. 7. For example, as shown in fig. 7, the next unit in the list (unit 3 in this example) may be selected for synchronization using the network ID field 130. The delay values described herein may be communicated to each unit and the user may confirm synchronization of each unit using the analysis portion 124. The status (e.g., the unit is being synchronized) may be displayed on the status display portion 144.

It should be noted that other user selectable members may be provided, for example, for exiting and resetting the user interface 120. Additionally, user selectable components may also be provided for loading information into and storing information from the user interface.

In addition, the user interface 120 may be provided as part of a portable device for synchronizing the units in the EAS system. Alternatively, the user interface 120 may be provided as part of a system device that may remotely access the EAS network.

Thus, various embodiments of the present invention provide for synchronizing transmissions of detection and deactivator units in an EAS system. In particular, using a single unit as a reference and communicating with other units via a communication link, e.g., a serial communication link, the delay of each unit relative to the reference unit, i.e., the master synchronization unit, can be determined, which is used to synchronize the transmissions of each unit.

Various embodiments or elements, such as the EAS system controller 22 or other controller, may be implemented as part of a computer system that may be separate from 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 device 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, 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 storage elements may also store data or other information as desired or needed.

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 be in response to a user command, or in response to a result of a previous processing, or in response 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 is to be understood that various embodiments thereof may be changed and modified without departing from the scope of the present invention. It is also to be understood that the scope of the various embodiments of the invention is not to be interpreted as limited to the specific embodiments disclosed herein, but only in accordance with the appended claims when read in light of the foregoing disclosure.

Claims (18)

1. A method for synchronizing transmissions in an electronic article surveillance, EAS, system, the method comprising:

determining a transmit timing difference between a plurality of units of the EAS system using a communication link of the EAS system; and

synchronizing transmission of each of the plurality of units based on the transmission timing differences,

wherein one of the plurality of units is a master synchronization unit, the method further comprising transmitting a broadcast message to the plurality of units to initiate a unit synchronization detection procedure for each of the units to determine a transmission timing difference based on a synchronization event of the master synchronization unit.

2. The method of claim 1, wherein the synchronization event is one of a zero-crossing and a transmission start time.

3. The method of claim 1, further comprising determining the transmission timing difference based on the count value for each of the units, a start of the count corresponding to receiving the broadcast message, and an end of the count corresponding to a next transmission for each of the units.

4. The method of claim 1, wherein the determining step is performed iteratively.

5. The method of claim 1, further comprising storing the transmit timing difference corresponding to each of the units in a memory of each of the units.

6. The method of claim 1, further comprising receiving measured timing information from each of the units for use in determining a transmission timing difference.

7. The method of claim 1, wherein the plurality of units includes an EAS detector unit and an EAS deactivator unit.

8. The method of claim 1, further comprising receiving user input to select a unit for synchronization.

9. The method of claim 1, further comprising providing a user interface for receiving user input to control synchronization.

10. The method according to claim 1, wherein said EAS system includes a serial network for communicating with each of said units.

11. A method for calibrating an electronic article surveillance, EAS, system to synchronize transmissions, the method comprising:

selecting one of a plurality of units of the EAS system as a master synchronization unit;

delivering a broadcast signal to the plurality of units according to a synchronization event of a master synchronization unit;

determining for each of said units a time period from receipt of the broadcast signal to the next transmission by that unit;

determining a difference between the time periods of the master synchronization unit and each of the other units; and

a delay is established for each unit based on the determined difference to synchronize the transmissions of each unit.

12. The method of claim 11, further comprising starting a counter within each cell upon receipt of a broadcast signal, the counter determining the time period.

13. The method of claim 11, further comprising transmitting a delay value to each cell based on the established delay.

14. The method of claim 11, further comprising communicating with each unit via a serial network.

15. The method of claim 11, wherein the units include an EAS detector unit and an EAS deactivator unit.

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

a plurality of units connected via a communication link, the plurality of units including a plurality of detector units and a plurality of deactivator units; and

a system controller configured to (i) determine a transmission timing difference between the plurality of units using the communication link and (ii) synchronize transmissions for each of the plurality of units based on the transmission timing difference,

wherein one of the plurality of units is a master synchronization unit and the system controller further transmits a broadcast message to the plurality of units to initiate a unit synchronization detection procedure of each of the units to determine a transmission timing difference based on a synchronization event of the master synchronization unit.

17. The EAS system of claim 16, wherein each of said units is configured to measure a time period from receipt of a broadcast message to a next transmission based on a synchronization event of the master synchronization unit, said time period being determined using a counter within each unit.

18. The EAS system of claim 16, further comprising a user interface for controlling synchronization, and wherein said user interface comprises a control portion and an analysis portion.