Patent Application
20090051534
1. Field Of The Invention
This invention relates generally to electronic article surveillance (EAS) systems and, more particularly, to a system and method for synchronizing transmissions in an EAS system.
In acoustomagnetic or magnetomechanical electronic article surveillance (EAS) systems, both detection and deactivation units may be provided. Both units typically excite an EAS tag by transmitting an electromagnetic burst at a resonance frequency of the tag. When the tag is present within the electromagnetic field created by the transmission burst, and has not been deactivated, the tag begins to resonate with an acoustomagnetic or magnetomechanical response frequency that is detectable by a receiver in both detection units. The detection unit may then provide some type of signal, for example, an alarm signal indicating the detection of a response from an EAS tag. The deactivation units also typically transmit a deactivation signal to deactivate the EAS tag such that the EAS tag will not resonate with an acoustomagnetic, magnetomechanical or electromagnetic response frequency when the EAS tag is present in the electromagnetic field of the detection units.
In EAS systems, the transmitter burst signal typically does not end abruptly, but instead decays exponentially because of transmitter circuit resonance. If the transmissions from nearby units are not synchronized, false detections may occur because all units transmit and receive at the same frequency. These false detections can result in false alarms and/or false deactivations.
In order to synchronize the transmissions from the detection and deactivation units of the EAS system, a manual synchronization process is typically performed. Specifically, field service personnel use, in connection with a configuration program, phasing tools that include two loop antennae and an oscilloscope to synchronize each of the units. The synchronization is provided by changing a delay time for the unit to transmit referenced from the AC zero-crossing point of the unit. This procedure is repeated for every deactivation and detection unit, for example, in a retail store.
However, because the wiring of the AC power supply to each of the units may be different, for example, the phase may be shifted by 120 degrees depending on how the power supply is wired (e.g., how the power outlet is wired), the AC zero-crossings can be different. This can result in improper synchronization of the units because the zero-crossings are out of phase. Further, isolation transformers for each unit can also affect the required delay for synchronization with the other units. Thus, the manual synchronization process is not only time consuming and susceptible to human error, for example, in reading the oscilloscope, but the reference for synchronizing the units may be different because of wiring differences in the power supply. Out of phase synchronization can thereby result.
Other known systems or processes for synchronizing the units within the EAS system provide for communicating the exact time of transmission for each of the units or use a reference signal transmitted by a broadcast transmitter to synchronize the units. However, because of internal delays within the units and other transmission delays, these processes often fail to adequately synchronize the units and are costly to implement. Further, a reliable twenty-four hour per day reception of signals from a selected FM or TV broadcast station is needed for providing a reference signal from a broadcast transmitter. This adds complexity and cost to the system.
Units within an EAS system also may be synchronized by periodically shutting down transmissions and then listening for other EAS transmitters from which a delay between the received signals and a AC zero-crossing of the shut down unit is determined. However, this process may not satisfactorily synchronize deactivator and detector units because of the large difference in transmit power and antenna size for these different types of units.
In one embodiment, a method for synchronizing transmissions in an electronic article surveillance (EAS) system is provided. The method may include determining a transmission timing difference between a plurality of units of the EAS system using a communication link of the EAS system and synchronizing transmissions for each of the plurality of units based on 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 synchronizing unit and communicating a broadcast signal to the plurality of units upon a synchronizing event of the master synchronizing unit. The method may further include determining for each of the plurality of units a time period from receiving the broadcast signal to a next transmission of the unit and determining a difference between the time period for the master synchronizing unit and each of the other units. The method may also include establishing a delay for each of the units based on the determined difference to synchronize transmissions for each of the units.
In yet another embodiment, an electronic article surveillance (EAS) system is provided that may include at least one of a plurality of detector units and a plurality of deactivator units connected via a communication link. The EAS system may further include 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.
For a better understanding of various embodiments of the invention, reference should be made to the following detailed description which should be read in conjunction with the following figures wherein like numerals represent like parts.
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 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
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 also controls transmissions from the deactivator units 26 and receptions received by the deactivator units 26 as is known to deactivate EAS tags having a predetermined characteristic and that are within a certain range of the deactivator units 26.
The detector units 24 and deactivator units 26 may be of any type as desired or needed, for example, a Sensormatic® detector unit or deactivator unit available from Tyco Fire & Security of Boca Raton, Fla. As an example,
In addition, controller 46 may be configured to control transmissions from transmitter 42 and receptions at receiver 44 such that the antenna pedestals 36 and 38 can be utilized for both transmission of signals to the EAS tag 34 and reception of signals generated by the EAS tag 34. In operation, and for example, upon receiving a signal from an EAS tag 34 within the detection area 32 that has not been deactivated by the deactivator unit 26, a visual and/or audible alarm may be provided.
Detector unit 24 is representative of many detector systems and is provided as an example only. For example, in an alternative embodiment, control unit 40 may be located within one of the antenna pedestals. In still another embodiment, additional antennas that only receive frequencies from the EAS tags 34 may be utilized as part of the EAS system 20. Also, a single control unit 40, either within a pedestal or located separately, may be configured to control multiple sets of antenna pedestals.
As a further example,
In addition, controller 64 may be configured to control transmissions from transmitter 60 and receptions at receiver 62 such that the deactivator portion 50, which may include one or more antennas (not shown), can be utilized for both transmission of signals to an EAS tag, for example, provided as part of an item label or package, and reception of signals generated by the EAS tag. In operation, and for example, upon receiving a signal from an EAS tag within the deactivation area 52 having a predetermined characteristic, the transmitter 60 may transmit a deactivation signal to deactivate the EAS tag as is known.
Deactivator unit 26 is representative of many deactivator systems and is provided as an example only. For example, in an alternative embodiment, control unit 58 may be located within the barcode scanner unit 54. In still another embodiment, the deactivator portion 50 may be configured having a different shape and orientation, for example, oriented transversely as opposed to longitudinally as shown in
Various embodiments of the invention provide for synchronizing transmissions in an EAS system, and more particularly, synchronizing transmission from the detector units 24 and deactivator units 26. It should be noted that each of the detector units 24 and deactivator units 26 may be assigned a unique address, and more particularly, each control unit associated therewith may be assigned, for example, a unique serial number. Further, the detector units 24 and deactivator units 26 may include, for example, processors and or memory provided as part of the controllers of these units for storing information.
It should be noted that communication and configuration of the units within the network may be provided using any known communication and control program and user interface as desired or needed. For example, in one embodiment, the communication and configuration functionality may be provided via a Configurator interface available from Tyco Fire & Security of Boca Raton, Fla.
Upon identifying the units at 72, one of the plurality of detector and deactivator units may be selected as the master synchronizing unit at 74. For example, a user may select one of the identified units as the master synchronizing unit via a user interface. After selecting a master synchronizing unit, at 76 a broadcast message may be communicated to all of the identified units. The broadcast message is communicated upon a synchronizing event of the master synchronizing unit.
Upon receiving the broadcast message, a unit synchronizing detection process 100 as shown in
Based upon the difference, a delay for each of the units may be determined at 82. For example, the calculated difference value for each of the units may be converted to a delay value corresponding to the calculated difference in count values. The delay value for each of the units may then communicated to the corresponding unit at 84 to delay each transmission from that unit, for example, delayed from a master clock. Thus, each of the units may now be synchronized with respect to all of the other units, and in particular, each of the periodic transmissions from each of these units is synchronized.
It should be noted that the method 70 may be performed iteratively until a minimum timing difference between the units is achieved. This iterative process may be performed, for example, for an individual unit, until the timing difference is less than a predetermined value, for example, such that transmissions will not interfere with receptions. For example, the predetermined value may be fifty microseconds.
Referring now to
The count information, which defines timing information for each of the units may then be stored at 108, for example, stored within a Random Access Memory (RAM) of each of the units. The timing information, which in this embodiment is a count value, may be communicated to the master synchronizing unit at 110 upon a request therefrom. Thereafter, at 112, each unit may receive a delay value as described above for delaying transmissions of that unit based on the timing information. For example, the delay value may be communicated to the control unit of each of the detector and deactivator units for use in delaying each transmission from the transmitter of the units. It should be noted that the delay for each of the units may be different.
The various embodiments of the invention also may include a user interface for controlling the synchronization of the units of the EAS system as described herein. For example, as shown in
The transmission timing of one or more of the selected units is displayed on the analysis portion 124, which in this embodiment, is configured as an oscilloscope. It should be noted, and as shown, the timing of transmissions of these units may not be synchronized. Upon selecting a master synchronizing unit, a synchronizing process, for example, as shown and described with reference to
After the first unit is synchronized with the master synchronizing unit, as shown by the analysis portion 124 in
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 members for loading and storing information to and from the user interface also may be provided.
Further, 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, the various embodiments of the 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 the other units via a communication link, for example, a serial communication link, a delay for each of the units relative to the reference unit, namely the master synchronizing unit, may be determined and used to synchronize the transmission of each of the units.
The various embodiments or components, for example, the EAS system controller 22 or other controllers, may be implemented as part of a computer system, which may be separate from or integrated with an EAS system. The computer system may include 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 further may 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, 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 that are stored in one or more storage elements, in order to process input data. The storage elements may also store data or other information as desired or needed. The storage element may be in the form of an information source or a physical memory element within 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 also may include modular programming in the form of object-oriented programming. The processing of input data by the processing machine may be in response to user commands, or in response to results of 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 variations and modifications of the various embodiments of the present invention can be made without departing from the scope thereof. It is also to be understood that the scope of the various embodiments 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 forgoing disclosure.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2005/032329 | 9/9/2005 | WO | 00 | 3/8/2008 |
