HK1113008B - Eas reader detecting eas function from rfid device - Google Patents

Description

EAS reader to detect EAS functionality from RFID devices

Cross Reference to Related Applications

This application claims priority under 35u.s.c. § 119, U.s. provisional patent application serial No.60/629,571 entitled "INTEGRATED 13.56.56 mhz eas/RFID DEVICE", filed 11, 18, 2004, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to an integrated Electronic Article Surveillance (EAS) and Radio Frequency Identification (RFID) system capable of performing dual EAS/RFID functions at an RFID designated frequency of 13.56MHz, and more particularly to a device capable of detecting an EAS detection signal from an RFID device at an RFID designated frequency of 13.56MHz without activating the RFID function of the RFID device.

Background

With the advent of RFID technology, many retailers are considering tagging merchandise (e.g., per item, per frame, per pallet) with RFID tags. Meanwhile, Electronic Article Surveillance (EAS) technology and devices have proven critical to reducing theft and are referred to as "loss". It is envisioned that RFID devices can also provide many of the same advantages known from EAS technology as well as additional advantages or capabilities such as inventory control, shelf reading, non-line-of-sight reading, and the like. However, there are several problems that pertain to previously known combination EAS and RFID devices or tags or labels. These problems include the following:

cost-a combination EAS/RFID tag or label is typically more expensive for the retailer or manufacturer since two devices and two separate readers or decoders are typically required.

The size of the size-combination structure is generally larger and often multiple physical overlaps result in reduced performance.

Interference-if devices are overlapped, interference can occur, resulting in reduced performance of either or both of the EAS and RFID functions, unless specific design features are provided to reduce interference caused by the overlap.

These problems associated with cost, size and performance degradation and interference caused by overlap are addressed and overcome in co-pending U.S. provisional patent application No.60/628,303, filed on 11/15/2004, entitled "Combo EAS/RFID Label orTag," the entire contents of which are incorporated herein by reference.

Needless to say, a 13.56MHz EAS reader device is still required to be able to read the signal from the RFID device as an EAS article detection signal. In addition, there remains a need for an integrated 13.56MHz EAS and RFID detection system having an EAS reader device that can read signals from the RFID device as EAS article detection signals.

Disclosure of Invention

It is an object of the present disclosure to perform an EAS function via an EAS reader coupled to an RFID tag or device. It is a further object of the present invention to provide an integrated EAS and RFID system that can detect the presence of an RFID device through a resonant circuit based on or due to the resonance of the circuit.

It is another object of the present disclosure to provide an EAS reader integrated into an RFID system to allow for a greater detection distance or read range than is available from conventional EAS reader and EAS tag combinations. The present disclosure also relates to EAS detection systems configured with smaller, lower cost tags through greater simplification.

The present disclosure relates to a reader device for an Electronic Article Surveillance (EAS) system, including a reader device configured to operatively communicate with a Radio Frequency Identification (RFID) tag. An energy level equal to an operating frequency of the RFID tag located within a read range of the reader device, wherein the energy level of the burst of electromagnetic energy is sufficient to generate a ringing signal by the RFID tag upon termination of generation of the pulse train of electromagnetic energy, wherein the reader device detects the ringing signal received from the RFID tag, the detection of the ringing signal being interpreted by the reader device as an EAS function. The reader device may include an actuator; a transmitter operatively coupled to the exciter through a first signal gate; a transmitter antenna operatively coupled to the transmitter; a receiver antenna having a front end; and a signal detector operatively coupled to the front end of the receiver through a second signal gate, wherein the exciter generates a pulse train of electromagnetic energy. The exciter may be one of a pulsed and continuous wave exciter. The EAS reader device may generate a burst of electromagnetic energy at a baseline frequency of 13.56 MHz. The pulse train of electromagnetic energy includes signals from RFID tags within a read range of the EAS reader. The first signal gate disables the transmitter and the second signal gate enables the receiver to receive signals from the RFID tag. Upon detection of the signal from the RFID tag, the signal detector initiates an alarm operatively coupled to the signal detector.

The electromagnetic energy may have a maximum field strength of 84db μ V/m at a distance of 30 meters from the reader, and the electromagnetic energy fluctuates within a frequency range of 7kHz relative to a baseline frequency. In addition, the electromagnetic energy may have a maximum field strength of 50.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic field fluctuates within a frequency range of ± 150kHz relative to the baseline frequency. Further, the electromagnetic energy may have a maximum field strength of 40.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic field fluctuates within a frequency range of + -450 kHz relative to the baseline frequency. Additionally, the electromagnetic energy may have a maximum field strength of 29.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic field fluctuates in a frequency range greater than + -450 kHz relative to the baseline frequency.

The present disclosure also relates to a method of detecting an Electronic Article Surveillance (EAS) function from a Radio Frequency Identification (RFID) tag. The method includes the step of providing a reader device configured to operatively communicate with the RFID tag. In addition, the reader device has a reading range. The method further includes the step of generating a pulse train of electromagnetic energy by a reader device having an energy level. The energy level is generated at an operating frequency of the RFID tag that is within a read range of the reader device. The energy level is sufficient to generate a ringing signal from the RFID tag upon termination of the pulse train generating electromagnetic energy. The method includes transmitting a burst of pulses to a spatial region at least within the read range and detecting whether a ring signal has been received from an RFID tag within the read range of the reader device to indicate the presence of the RFID tag within the read range. The detected ringing signal is interpreted by the reader device as an EAS function.

The step of transmitting the pulse train to at least the spatial region within the reading range may comprise the steps of transmitting the pulse train via a transmitter operatively connected to the reader device, via a transmitting antenna, and disconnecting the transmitter of the reader device. The step of detecting whether a signal is received from an RFID tag within a read range of the reader device may comprise the step of enabling the receiver to be coupled to a receiver antenna of the reader device.

The method may further include the steps of generating an alert if a signal has been received from an RFID tag within a read range of the reader device, generating an energy level at an operating frequency of the RFID tag that is within the read range of the reader device if a signal has not been received from an RFID tag within the read range of the reader device, and generating a pulse train of electromagnetic energy by the reader device having an energy level sufficient to generate a ring signal by the RFID tag after terminating the generation of the pulse train of electromagnetic energy. The method includes the steps of generating a burst of electromagnetic energy from a reader device having an energy level sufficient to generate a ring signal by the RFID tag after terminating the generation of the burst of electromagnetic energy.

The method may include generating a pulse train of electromagnetic energy at a baseline frequency of about 13.56 MHz. The method may be carried out by electromagnetic energy having a maximum field strength of 84db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuating within a frequency range of ± 7kHz relative to a baseline frequency. In addition, the method may be practiced with electromagnetic energy having a maximum field strength of 50.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuates within a frequency range of ± 150kHz relative to a baseline frequency. Again, the method may be practiced with electromagnetic energy having a maximum field strength of 40.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuating within a frequency range of + -450 kHz relative to a baseline frequency. The method may also be practiced with electromagnetic energy having a maximum field strength of 29.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuating over a frequency range greater than + -450 kHz relative to a baseline frequency.

Drawings

The subject matter regarded as the embodiments is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, the embodiments, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

FIG. 1 is an overview of a common RFID tag or label device;

FIG. 2 is a schematic diagram of a common RFID reader connected to RFID devices;

FIG. 3 is a schematic diagram illustrating an EAS reader for use with an RFID device in accordance with the present disclosure;

FIG. 4 is a functional block diagram of the EAS reader of FIG. 3;

FIG. 5 is a diagram illustrating a method of detecting EAS functionality from an RFID tag in accordance with the present disclosure;

FIG. 6A is a theoretical plot of EAS burst signals generated by an EAS reader versus time in accordance with the present disclosure;

FIG. 6B is a theoretical plot of response signal versus time for RFID devices within a read range of an EAS reader device according to the present disclosure, as detected by the EAS reader device;

FIG. 6C is a graphical representation of an EAS reader device receiver detection enable/disable state versus time in accordance with the present disclosure; and

figure 7 is a graph showing sideband generation as a result of pulsing a 13.56MHz transmit field.

Detailed Description

Numerous specific details may be set forth herein to provide a thorough understanding of embodiments of the invention. However, it will be understood by those skilled in the art that the various embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the various embodiments of the invention. It can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the invention.

It should be noted that any reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment in accordance with the disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

For example, some embodiments may be described using the term "connected" to indicate that two or more elements are in direct physical or electrical contact with each other.

The present disclosure is directed to an apparatus and method for performing an EAS function with an RFID tag. By this approach, significant cost and space savings are achieved by using one tag to achieve dual functionality. The RFID function may be used for logical operations such as manufacturing process control, goods shipping, inventory, item verification for checkout, profit, and the like. At the exit point, an EAS function may then be performed for anti-theft purposes.

RFID tags based on the 13.56MHz system have a front end resonant circuit with a Q factor of about 35 to 65 in order to capture electromagnetic energy including the voltage in the resonant circuit. There is a minimum field requirement for the RFID functionality to operate so that the voltage sensing equals or exceeds the threshold voltage at which the RFID functionality is enabled. The EAS system of the present disclosure is designed to detect only the resonance of the resonant circuit of the RFID tag. Because the response of the resonant circuit is proportional to the input magnetic field, the detection distance or read range of such a system may be large and there is no minimum field requirement. Thus, the same RFID tag may be used as a dual use device for EAS and RFID applications.

Referring now in detail to the drawings in which like numerals may be used to designate like components, FIG. 1 illustrates an overview of a common 13.56MHz RFID device or security tag or label 100. Security tag 100 is generally comprised of two main parts: a planar inductor element or antenna 104 mounted on a flexible substrate 102. The flexible substrate 102 may be made of plastic or paper. An RFID Integrated Circuit (IC) or chip 108 is connected to the planar inductor element or antenna 104, either directly or via a lead frame 106. The RFID security tag or label 100 may include a covering material 110 mounted on an IC or chip 108.

As best shown in fig. 2, a public RFID security system 200 includes a security tag 100. The IC or chip 108 includes a built-in capacitor 204(C2) forming a resonant circuit 212 through the planar inductor element or antenna 104 (L2). If there is insufficient capacitance in the resonant circuit 212 to tune the resonant circuit 212 to the proper frequency, only the built-in capacitor 204 is needed (C2), otherwise the capacitor C2 may be omitted.

The RFID system 200 may also include an RFID reader 202.RFID reader 202 may include a tuned circuit 208 having an inductor L1 and a capacitor C1 connected in series. Capacitor C1 is only needed if there is insufficient capacitance in the tuning circuit 208 to adjust the frequency, otherwise capacitor C1 may be omitted. RFID reader 202 may be configured to generate pulsed or Continuous Wave (CW) RF power across tuned circuit 208 that is electromagnetically coupled to resonant circuit antenna 212 of RFID security tag 100 by alternating current. The mutually coupled CW RF electromagnetic power from the RFID security tag is coupled to the RFID reader 202 by the magnetic field 214.

RFID security tag 100 is a power converter circuit that converts some of the coupled CW RF electromagnetic power 214 into direct current signal power for use by the logic circuits of semiconductor IC108 used to implement RFID operations for RFID device 100. Depending on the structure of the RFID security tag or label 100, the resonant frequency of the tuned circuit 208 is targeted at 13.56MHz and the quality factor Q is from about 30 to about 70.

The RFID device or security tag 100 may include a memory to store RFID information and transmit the stored information in response to an interrogation signal 210. RFID information may include any type of information that can be stored in a memory used by RFID device 100. Examples of RFID information include a unique tag identifier, a unique system identifier, an identifier for the monitored object, and so forth. In this context, the type and amount of RFID information is not limited.

In general operation, when the resonant circuit 212 of the RFID device 100 is in proximity to the tuned circuit 208 of the RFID reader 202, an Alternating Current (AC) voltage V is generated across terminals T1 and T2 of the resonant circuit 212 of the RFID device 100_i. Rectifying the AC voltage Vi of the resonant circuit 212 to a Direct Current (DC) voltage, and when the magnitude of the rectified voltage reaches a threshold V_TThe RFID device 100 is activated upon activation, the RFID device 100 transmits the stored data in the memory register by modulating the interrogation signal 210 of the RFID reader 102 to form a response signal 216, the RFID device 100 then transmits or backscatter scatters the response signal 216 to the RFID reader 202 receives the response signal 216 and converts them into a detected serial data word bit stream of data representing information from the RFID device 100.

The RFID system 200 shown in FIG. 2 may be considered a High Frequency (HF) RFID system because the RFID reader 202 is inductively coupled to the RFID device 100 via the magnetic field 214.

The front end current receiving resonant circuit 212 of the above-described RFID device or security tag 100, which is based on a carrier frequency of 13.56MHz, has a Q factor of about 35 to about 65 in order to capture electromagnetic energy. The Q factor is a measure of the resonant frequency, the voltage and current boost in the resonant circuit, and can be calculated by one skilled in the art based on the particular configuration of resonant circuit 212. By taking the ratio of the resonant frequency to the Q factor, the bandwidth of the antenna is calculated.

For an RFID system 200 that detects codes stored in the IC108 of a passive RFID device 100, electromagnetic radiation 214 must be emitted via a carrier frequency of 13.56 Mz.

In addition, the transmit waveform is also encoded to facilitate the communication path between RFID tags/labels within detection zone Z1. RFID device 100 is physically separated from RFID reader 202 by distance d 1. The detection zone Z1 is defined as the imaginary surface at an effective distance Z1 typically produced by inductor L1. The effective distance Z1 defines a read range such that if the distance d1 is less than or equal to the read range Z1, the RFID reader 202 senses the desired threshold voltage V_TTo activate the RFID device 100. The read range Z1 is dependent on, among other factors, the strength of the EM field radiation 214 from the tuned circuit 208. Thus, the intensity of the EM field radiation 214 determines the read range Z1.

For EAS applications, the presence of RFID device 100 only has to be detected by detecting only resonant circuit 212, without the need to read the code stored therein. As explained in more detail below, detecting only resonant circuit 212 does not require a minimum induced voltage, i.e., a threshold voltage V, across terminals T1 and T2 of resonant circuit 212_T. Thus, the presence of RFID device 100 for EAS applications can be more efficiently detected.

In particular, FIG. 3 shows an integrated EAS and RFID system 300 according to one particularly useful embodiment of the present disclosure. The integrated RAS and RFID system 300 includes an RFID device or security tag 100 and a resonant circuit 212. The integrated EAS and RFID system 300 may be configured to operate using an RFID device 100 having an operating frequency in the 13.56MHz frequency band. However, RFID system 100 may also be configured to operate using other portions of the RF spectrum as desired for a given implementation. In this context, the embodiments are not limited. As shown in FIG. 3, the integrated EAS and RFID system 300 may include a plurality of nodes. The term "node" as used herein may refer to a system, element, module, component, circuit board, or device that may process a signal representing information. The signal may be, for example, an electrical signal, an optical signal, an acoustic signal, and/or a chemical signal.

More specifically, the integrated EAS and RFID system 300 differs from the RFID system 100 of fig. 2 only in that the RFID reader having the additional tuning circuit 208 consisting of the inductor L1 and the capacitor C1 connected in series is replaced with an EAS reader 302 having an additional tuning circuit 308 consisting of an inductor L3 and a capacitor C3 connected in series. Again, capacitor C3 is only needed if there is insufficient capacitance in the tuning circuit 308 to tune to the proper frequency, otherwise capacitor C3 may be omitted.

As in the case of RFID reader 202, EAS reader 302 is configured to generate pulsed or Continuous Wave (CW) RF power across tuned circuit 308 that is electromagnetically coupled to resonant circuit antenna 212 of RFID security tag 100 by an alternating current action. The mutually coupled CW RF electromagnetic power from RFID device 100 is coupled to EAS reader 302 via magnetic field or pulse train 314.

Although RFID security tag 100 is still a power conversion circuit that converts some coupled CW RF electromagnetic power or pulse train 314 into DC signal power for use by the logic circuits of semiconductor IC108 used to implement RFID operation of RFID device 100, unlike the case of RFID reader 202, even though EAS reader 302 may induce a threshold voltage V, which may be exceeded, across terminals T1 and T2 of resonant circuit 212 of RFID security tag 100_T1Voltage V of_iAnd the energy level of the pulse train 314 is sufficient to generate a ring signal 316 by the RFID device 100, the reader device 302 detects the ring signal 316 received from the RFID tag and interprets the ring signal 316 as an EAS function or EAS response signal or article detection signal. Thus, although in general operation, when resonant circuit 212 of RFID device 100 is in proximity to tuned circuit 308 of EAS reader 302 (i.e., circuit 212 and circuit 308 are separated by distance d 2), an Alternating Current (AC) voltage V is developed across resonant circuit 212 of RFID device 100_iAnd an AC voltage V across the resonant circuit 212_iRectified to a Direct Current (DC) voltage) even though the threshold voltage V may be exceeded_TThe EAS reader 302 does not activate the RFID device 100. No command code is transmitted from the EAS reader 302 in order to activate the RFID device 100. Thus, no interrogation signal 210 is generated due to the deactivation of the RFID device 100.

Since no RFID function is required to operate, by sensing the current and magnetic field in the inductor 104(L2) as a result of the EM field 314 generated by the EAS reader 302, very low power is required to generate only the EAS article detection signal 316. After the generation of electromagnetic energy 314 is completed, only enough power is required to generate a ring signal 316 from RFID tags within read range Z2. Therefore, the inductor voltage Vi can be much smaller than the activation voltage V for the RFID function_T。

RFID functionality is typically present in RFID devices or security tags 100. In addition, the resonant circuit 212 is always present in the RFID device 100. Generally, signal 316 is generated by RFID device 100 regardless of the EAS state of the article (e.g., for an article, whether or not the article is paid for). Commonly owned, U.S. provisional patent application No.60/630,315, PCT application serial No. [ document No. f-TP-00013US/WO ], entitled "INTEGRATED EAS/RFID DEVICEAND DISABLING DEVICES THEREFOR," filed on 23/11/2004, entitled "DISABLING DEVICES AN INTEGRATED EAS/RFID DEVICE," addresses the problem associated with controlling the generation of signals 316 by RFID DEVICES 100 in an integrated EAS/RFID detection system, the entire contents of which are incorporated herein by reference.

As previously described, RFID device 100 is physically separated from EAS reader 302 by distance d 2. The detection zone Z2 is defined as the imaginary surface at an effective distance Z2 typically produced by inductor L2. The effective distance Z2 defines a read range such that if the distance d2 is less than or equal to the read range Z2, the EAS reader 302 can read the EAS article detection signal 316.

The read range Z2 is dependent on, among other factors, the strength of the EM field radiation 314 from the tuned circuit 308. Thus, the intensity of the EM field radiation 314 determines the read range Z2. Since the response of resonant circuits 212 and 308 is proportional to the input magnetic field or pulse train 314, the read range Z2 of integrated EAS and RFID system 300 can be large and there is no minimum field requirement. Thus, the same tag can be used as a dual-use device for EAS and RFID applications.

The integrated EAS and RFID system 300 shown in fig. 3 may be considered a High Frequency (HF) integrated EAS and RFID system because the EAS reader 302 may be inductively coupled to the RFID device 100 via a magnetic field or pulse train 314.

Fig. 4 illustrates a schematic diagram of one embodiment of an EAS reader 302 of the present disclosure. More specifically, the reader device 302 includes an actuator 402 that provides a pulsed or Continuous Wave (CW) burst transmission 314 that is operatively coupled to a transmitter 406 via a first signal gate 404. The EAS reader 302 additionally includes a transmitter antenna 408, and the transmitter 406 is operatively coupled to the transmitter antenna 408. A burst transmission 314 of electromagnetic energy may be generated for approximately 13.56MHz of the designated frequency of us RFID transmission and reception.

The reader device 302 further includes a receiver antenna 422 that receives the signal 316, which is operatively coupled to a receiver front end 424. Conversely, the receiver front end 424 is operatively coupled to the signal detector 428 via the second signal gate 426. Typically, the signal detector 428 is further operatively coupled to an alarm 430. When the first signal gate 404 is enabled, the second signal gate 426 is disabled. Conversely, when the first signal gate 404 is disabled, the second signal gate 426 is enabled.

In the views of fig. 3 and 4, fig. 5 and 6A through 6C disclose a method 500 of detecting an Electronic Article Surveillance (EAS) function from a Radio Frequency Identification (RFID) device tag or label 100, more particularly, the method includes a step 502 from a time t₀To time t₁After the generation of the burst of electromagnetic energy 314 is complete, a burst of electromagnetic energy 314 is generated from the EAS reader 302 at an energy level "e 1" sufficient to generate a ring signal 316 by the RFID devices 100 within the read range Z2. The burst 314 may be transmitted to at least an area of space within the read range Z2 and may be transmitted through the antenna 408 via the transmitter 406 of the EAS reader 302. At time t₁The method may include the step 504 of turning off the transmitter 406 of the EAS reader 302 and the step 506 of enabling the receiver 424 coupled to the receiver antenna 426 of the EAS reader 302 may be implemented substantially simultaneously, or with a predetermined time delay. The method 500 further includes a step 508 of detecting via a detector 428 whether a signal 316 in the form of an attenuated or "ringing" signal, indicative of the presence of an RFID device 100, has been received from RFID tag 100 within a read range Z2 of EAS reader 302 via receiver 424. The "ring" signal 316 is an attenuated signal that has been caused by the burst of the transmitted signal 314 and is interpreted by the EAS reader 302 as an EAS response or article surveillance signal.

If a "ring" signal 316 has been received from RFID tag 100 within the read range R2 of EAS reader 302, typically via receiver 424, the method further includes the step 610 of generating an alarm. If a signal has not been received from an RFID tag 100 within the reading range Z2 of the EAS reader 302, the method 500 includes the step 512 of disabling the receiver 424 and, after a predetermined period of time, may be substantially simultaneous, after the end of generating the burst of electromagnetic energy 314, again achieving the step 502 of generating the burst of electromagnetic energy 314 by the EAS reader 302 at an energy level "e 1" sufficient to generate a ring signal 316 by an RFID device 100 within the reading range Z2. In one embodiment, the pulse train 314 of electromagnetic energy is generated at about 13.56MHz for a specified RFID baseline frequency for the United states, as previously described.

In one embodiment, the transmit antenna 408 and the receive antenna 422 are combined into a single antenna that transmits and receives the burst 314 and the EAS response signal 316 interchangeably or simultaneously.

Since the EAS reader 302 may be capable of operating at less than the threshold voltage V_TInduced voltage V of_iDetecting EAS merchandise detection Signal 316, read Range Z₂Can be larger than the reading range Z₁。

For the integrated EAS and RFID system 300 that detects the EAS article detection signal 316 returned from the passive RFID device 100, in one embodiment, electromagnetic radiation 314 is emitted at a carrier frequency of 13.56 MHz.

To have an EAS function compatible with an RFID function, the integrated EAS reader device and RFID device 300 should function within the requirements imposed by a regulatory agency having jurisdiction. An example of such regulatory requirements is the requirement that at 13.56MHz, the radiation of energy must be contained within ± 7 kHz.

Thus, the low induced voltage V with the integrated EAS and RFID system 300 for the present disclosure_iRegardless, the radiation of energy must be contained within 7kHz, as shown in FIG. 7. The limits of the frequency mask are shown as line 700 in fig. 7. Centered at 13.56MHz, the electric field or signal intensity "e" at a distance of 30 meters from the EAS reader device 302 is not enabled to exceed intensities 84, 50.5, 40.5, and 29.5 decibel microvolts per meter (db μ V/m) within 7kHz, 150kHz, 450kHz, or greater than 450kHz, respectively. In table 1 below, exemplary management requirements are also tabulated:

to fit within the frequency of regulatory requirements, the electromagnetic energy pulse train 314 and the transmission of the EAS article detection signal 316 need to be close to a single tone frequency, if any, by low degree modulation.

Figure 7 also shows a spectrum 710 of a pulsed system with pulsed waves of electromagnetic energy at about 13.56MHz at a pulse repetition rate of about 60 hz, i.e., 60 pulses/second, and an actual pulse period roughly about 2.5ms in duration. Since the available pulse duration corresponds to the inverse of the pulse repetition rate, i.e. 1/60 seconds/pulse 0.0167 seconds/16.7 ms, the duty cycle for the pulse system is equal to 2.5ms/16.7ms, about 15%. With a duty cycle of about 15%, the energy sideband generated by this waveform 710 is under the exemplary frequency mask 700.

By providing different reader system hardware, the passive integrated EAS/RFID tag 100 can function as both an EAS and RFID device or perform both EAS and RFID functions.

As shown in fig. 3. Those skilled in the art will appreciate that the EAS reader 302 need not be a separate device and may be integrated as part of a combined multi-function device including at least the combined RFID and EAS reader 320. Thus, reader device 320 is capable of reading both EAS and RFID functions of RFID device 100.

In view of the exemplary regulatory requirements shown in FIG. 7, the exciter 402 generates electromagnetic energy "e" at a baseline frequency of 13.56 MHz. In one embodiment of the method 500, the electromagnetic energy "e" has a maximum field strength "e 1" of 84db μ V/m at a distance of 30 meters from the reader device 302, and the electromagnetic energy "e" fluctuates within a frequency range of 7kHz relative to a baseline frequency of 13.56 MHz. In one embodiment of the method 500, the electromagnetic energy "e" has a maximum field strength "e 1" of 50.5db μ V/m at a distance of 30 meters from the reader device 302, and the electromagnetic energy "e" fluctuates within a frequency range of ± 150kHz relative to the baseline frequency.

In one embodiment of the method, the electromagnetic energy "e" has a maximum field strength "e 1" of 40.5db μ V/m at a distance of 30 meters from the reader device 302, and the electromagnetic energy "e" fluctuates within a frequency range of + -450 kHz relative to the baseline frequency.

In one embodiment of the method 500, the electromagnetic energy "e" has a maximum field strength "e 1" of 29.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy "e" fluctuates over a frequency range greater than + -450 kHz relative to the baseline frequency.

One of ordinary skill in the art will appreciate that although the present disclosure is directed to an EAS reader device that reads EAS functionality from an RFID device operating at a baseline frequency of 13.56MHz, which is the U.S. specified RFID frequency, the EAS reader device 302 may be configured to read EAS functionality from an RFID device operating at any other specified RFID baseline frequency. In this context, the embodiments are not limited.

In general, the present disclosure is directed to an EAS reader device or a combination EAS and RFID reader capable of performing an EAS function by recognizing a signal generated by an inductively coupled antenna resonant circuit included in an RFID security tag or label. By this method, by using one tag, significant savings can be achieved in order to achieve dual functionality. RFID functionality can be used for logical operations such as manufacturing process control, merchandise shipping, inventory, checkout of items at check out, profit, and the like. At the exit point for the article, an EAS function can be performed for theft prevention purposes. In addition, the read range for EAS may be extended beyond the read range of existing EAS tags or labels.

From the above, a system can be constructed in hardware to detect the presence of an RFID device based on the resonance of the RFID component. Such systems are expected to have a greater detection range. In addition, the same RFID tag can perform additional EAS functions at the exit while retaining all necessary functionality, such as shelf reading, checkout, inventory control, and the like. More specifically, the present disclosure allows the label or tag to be designed with the following advantages: (1) integrating EAS and RFID functions; (2) lower installation and operating costs (one combined EAS/RFID system versus two separate systems); and (3) unifying dual-function performance in system design.

While certain features of the embodiments of the invention have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications as fall within the true spirit of the embodiments of the invention.

Claims (19)

1. An Electronic Article Surveillance (EAS) reading system comprising:

a reader device configured to operatively communicate with a Radio Frequency Identification (RFID) tag,

wherein the reader device comprises:

an exciter configured to generate a pulse train of electromagnetic energy having an energy level equal to an operating frequency of an RFID tag located within a reading range of the reader device, the energy level being sufficient to generate a ringing signal by the RFID tag upon termination of generation of the pulse train of electromagnetic energy;

a transmitter operatively coupled to the exciter through a first signal gate;

a transmitter antenna operatively coupled to a transmitter, the transmitter antenna for transmitting a burst of electromagnetic energy;

a receiver antenna having a front end, the receiver antenna for receiving a ringing signal; and

a signal detector operatively coupled to the front end of the receiver through the second signal gate, the signal detector for detecting a ring signal received from the RFID tag without activating the RFID function of the RFID tag, wherein detecting the ring signal is interpreted by the reader device as an EAS detection signal to indicate the presence of the RFID tag.

2. An Electronic Article Surveillance (EAS) reading system as recited in claim 1, wherein the exciter is one of a pulsed and continuous wave exciter.

3. An Electronic Article Surveillance (EAS) reading system as claimed in claim 1, wherein the second signal gate disables the receiver when the first signal gate allows the transmitter to transmit the pulse train.

4. An Electronic Article Surveillance (EAS) reading system as recited in claim 1, wherein the EAS reader device generates a pulse train of electromagnetic energy at a baseline frequency of about 13.56 MHz.

5. An Electronic Article Surveillance (EAS) reading system as recited in claim 1, wherein the exciter generates the pulse train of electromagnetic energy at a baseline frequency of about 13.56 MHz.

6. An Electronic Article Surveillance (EAS) reading system as recited in claim 1, wherein the second signal gate allows the receiver to receive signals from the RFID tag when the first signal gate disables the transmitter.

7. An Electronic Article Surveillance (EAS) reading system as claimed in claim 6, wherein the signal detector detects the signal from the RFID tag.

8. An Electronic Article Surveillance (EAS) reading system as recited in claim 7, wherein the signal detector initiates an alarm operatively coupled to the signal detector upon detection of the signal from the RFID tag.

9. An Electronic Article Surveillance (EAS) reading system according to claim 4, wherein the electromagnetic energy has a maximum field strength of 84db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuates within a frequency range of ± 7kHz with respect to a baseline frequency.

10. An Electronic Article Surveillance (EAS) reading system according to claim 4, wherein the electromagnetic energy has a maximum field strength of 50.5db μ V/m at a distance of 30 meters from the reader device, and the electromagnetic energy fluctuates within a frequency range of ± 150kHz with respect to a baseline frequency.

11. An Electronic Article Surveillance (EAS) reading system according to claim 4, wherein the electromagnetic energy has a maximum field strength of 40.5db μ V/m at 30 meters from the reader device, and the electromagnetic energy fluctuates within a frequency range of ± 450kHz relative to a baseline frequency.

12. An Electronic Article Surveillance (EAS) reading system according to claim 4, wherein the electromagnetic energy has a maximum field strength of 29.5db μ V/m at 30 meters from the reader device, and the electromagnetic energy fluctuates over a frequency range greater than ± 450kHz relative to a baseline frequency.

13. A method of detecting Electronic Article Surveillance (EAS) functions from a Radio Frequency Identification (RFID) tag, the method comprising the steps of:

providing a reader device configured to operatively communicate with an RFID tag, the reader device having a read range;

generating, by a reader device having an energy level, a pulse train of electromagnetic energy, the energy level being generated at an operating frequency of an RFID tag located within a read range of the reader device, the energy level being sufficient to generate, by the RFID tag, a ring signal without activating an RFID function of the RFID tag after terminating the generation of the pulse train of electromagnetic energy;

transmitting the pulse train to a region of space at least within a read range; and

detecting whether a ring signal has been received from an RFID tag within a read range of the reader device to indicate the presence of an RFID tag within the read range, the detection ring signal being interpreted by the reader device as an EAS detection signal.

14. The method of claim 13, wherein the step of transmitting the burst to at least a region of space within the read range comprises the steps of:

transmitting, by a transmitter operatively connected to the reader device, a pulse train through a transmit antenna; and

the transmitter of the reader device is turned off.

15. The method of claim 14, wherein the step of detecting whether a signal has been received from an RFID tag within a read range of the reader device comprises the step of enabling a receiver coupled to a receiver antenna of the reader device.

16. The method of claim 14, wherein if a signal has been received from an RFID tag within a read range of the reader device, the method further comprises the steps of:

and generating an alarm.

17. The method of claim 14, wherein if no signal has been received from an RFID tag within a read range of the reader device, the method comprises the steps of:

waiting for a predetermined time period; and

generating a pulse train of electromagnetic energy by a reader device having an energy level sufficient to generate a ring signal by an RFID tag without activating the RFID function of the RFID tag after terminating the generation of the pulse train of electromagnetic energy, at an operating frequency of the RFID tag that is within a read range of the reader device.

18. The method of claim 15, wherein the method further comprises the steps of:

generating an alert if an RFID tag within a read range of the slave reader device has received a ringing signal by the receiver; and

wherein if a ring signal has not been received from an RFID tag within a read range of the reader device, the method comprises the steps of:

disabling the receiver;

waiting for a predetermined time period; and

repeating the step of generating a pulse train of electromagnetic energy by a reader device having an energy level sufficient to generate a ringing signal by an RFID tag without activating the RFID function of the RFID tag after terminating the generation of the pulse train of electromagnetic energy, at an operating frequency of the RFID tag that is within a read range of the reader device.

19. The method of claim 13, wherein the pulse train of electromagnetic energy is generated at a baseline frequency of about 13.56 MHz.