HK1178332B - Near field communications (nfc) devices and method for detecting a presence of nfc devices - Google Patents

Abstract

A near field communications (NFC) device that detects a presence of another NFC capable device within its magnetic field and method for detecting a presence of NFC device are disclosed. The NFC device provides a detection sequence having one or more detection signals to its environment. The NFC device observes the detection sequence as it is being provided to its environment to recover one or more observed detection signals. The NFC device determines a difference between the observed detection signals and one or more previous observed detection signals and/or the detection signals. The NFC device characterizes the difference as resulting from changes in the environment when the difference is linear or as resulting from another NFC capable device being present within its magnetic field when the difference is non-linear.

Description

Near field communication device and method of detecting presence of near field communication device

Reference to related applications

This application claims the benefit of U.S. provisional patent application No.61/499,489 filed on day 21/6/2011 and U.S. patent application No.13/249,820 filed on day 30/9/2011, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to Near Field Communication (NFC), and more particularly, to detecting the presence of NFC capable devices.

Background

Near Field Communication (NFC) devices are being incorporated into mobile devices, such as smartphones, to facilitate their use for everyday transactions. For example, rather than carrying a large number of credit cards, credit information provided by credit cards may be loaded into an NFC device and stored therein for use as needed. The NFC device simply taps the credit card terminal to forward the credit information to the terminal to complete the transaction. As another example, a ticket writing system, such as those used in terminals for buses and trains, may simply write ticket price information to an NFC device, rather than providing a paper ticket to a passenger. The passenger simply taps the NFC device to the card reader to take a bus or train without a paper ticket.

Generally, NFC includes a polling mode of operation to establish communication between NFC devices. A first conventional method detects the magnetic field of a first conventional NFC device for a second NFC device according to a predefined polling procedure. In this first conventional approach, the first conventional NFC device generates a magnetic field without any information for a predetermined period, usually referred to as a guard time, which depends on different technologies. Next, the first conventional NFC device detects a magnetic field of a first technology type (e.g., type a, type B, or type F as some examples) for the second NFC device using a conventional polling instruction after the expiration of the guard time. The normal polling instruction includes, for example, a normal request instruction of type a (REQA), a normal request instruction of type B (REQB), or a normal request instruction of type F (REQF). The first conventional NFC device then generates a magnetic field without any information at another guard time and, if no response is received from the second conventional NFC device, detects the magnetic field of the second technology type for the second NFC device using a conventional polling instruction. The first conventional method is described in more detail in "NFCForum: NFCActive specificity: technical specificity, NFCForumTMActivity 1.0" published at 18.11.2010, which is incorporated herein by reference in its entirety.

The guard time of the first conventional method unnecessarily consumes energy. Typically, the guard time is approximately 5 milliseconds when probing NFC devices of type a and type B, while the guard time may exceed 20 milliseconds when probing NFC devices of type F. Furthermore, the first conventional NFC device must generate a magnetic field without any information for more than one guard time and use more than one polling command to detect the magnetic field for some technologies. For example, a first conventional approach typically polls for a type a device, then polls for a type B device, and then polls for a type F device. In this example, the first conventional NFC device generates a guard time for devices of type A, B and F and provides REQA, REQB, and REQF commands to establish communication with NFC devices of type F.

A second conventional approach sends detection pulses with substantially the same amplitude to probe for the presence of an NFC device. The first NFC device continuously provides detection pulses until a change in amplitude of one of the detection pulses is detected. The change indicates the presence of a second NFC device within the magnetic field of the first NFC device. A second conventional approach is described more in U.S. patent application No.: 12/446,591, incorporated herein by reference in their entirety.

However, this simple detection of pulse changes is sensitive to changes in the environment. For example, moving a first NFC device around the environment may cause a change in the amplitude of one or more detection pulses. As another example, an object in the environment (e.g., a metal object or other NFC-incapable device as part of the example) entering the magnetic field may cause a change in the amplitude of one or more detection pulses. This change may be caused by a change in the environment alone, rather than from a second NFC present within the magnetic field. Naturally, the first NFC device may incorrectly determine that the second NFC device is present.

Therefore, there is a need to detect the presence of another NFC device within the magnetic field that overcomes the aforementioned drawbacks. Further aspects and advantages of the present invention will become apparent from the detailed description that follows.

Disclosure of Invention

One aspect of the present invention relates to a Near Field Communication (NFC) device, comprising: a modulator module configured to modulate the detection signal on a carrier to provide a modulated detection signal; an antenna module configured to apply the modulated detection signal to an inductive coupling element to generate a magnetic field to provide a detection sequence; a demodulation module configured to demodulate the detection sequence to provide an observed detection sequence; and a controller module configured to indicate a presence of a second NFC device within the magnetic field when the observed detection signal is non-linearly correlated with a previously observed detection signal.

In the NFC device according to the aspect, it is preferable that the detection signal is a monotonously increasing signal.

In the NFC device according to the aspect, it is preferable that the detection signal is a ramp signal.

In the NFC device according to the aspect, it is preferable that the controller module is further configured to compare the signal metric of the observed detection signal with the signal metric of the previously observed detection signal.

In the NFC device according to the aspect, it is preferable that the signal metric of the observed detection signal is a signal envelope of the observed detection signal, and the signal metric of the previously observed detection signal is a signal envelope of the previously observed detection signal.

In the NFC device of the aspect, it is preferable that the controller module is further configured to indicate that a second NFC device is not present when the observed detection signal is linearly related to the previously observed detection signal.

In the NFC device of the aspect, it is preferable that the controller module is further configured to indicate that a second NFC device is not present when the observed detection signal is substantially equal to the previously observed detection signal.

In the NFC device according to this aspect, it is preferable that the controller module is further configured to compare the signal metric of the observed detection signal with the signal metric of the previously observed detection signal to determine a signal metric change.

In the NFC device of this aspect, it is preferred that the controller module is further configured to characterize the signal metric change between detected signals as non-linear or linear to indicate a presence of a second NFC device within the magnetic field when the signal metric change is characterized as substantially non-linear and to indicate an absence of a second NFC device within the magnetic field when the signal metric change is characterized as substantially linear.

Another aspect of the invention relates to a Near Field Communication (NFC) device, comprising: a modulator module configured to modulate the detection signal on a carrier to provide a modulated detection signal; an antenna module configured to apply the modulated detection signal to an inductive coupling element to generate a magnetic field to provide a detection sequence; a demodulation module configured to demodulate the detection sequence to provide an observed detection sequence; and a controller module configured to indicate a presence of a second NFC device within the magnetic field when the observed detection signal is non-linearly related to the detection signal.

In the NFC device of the another aspect, it is preferable that the detection signal is a monotone increasing signal.

In the NFC device of the another aspect, it is preferable that the detection signal is a ramp signal.

In the NFC device of this further aspect, preferably the controller module is further configured to compare a signal metric of the observed detection signal to a signal metric of the detection signal.

In the NFC device according to the another aspect, it is preferable that the signal metric of the observed detection signal is a signal envelope of the observed detection signal, and the signal metric of the detection signal is the signal envelope of the detection signal.

In the NFC device of this further aspect, it is preferable that the controller module is further configured to indicate that a second NFC device is not present when the observed detection signal is linearly related to the detection signal.

In the NFC device of this further aspect, it is preferred that the controller module is further configured to indicate the absence of a second NFC device when the observed detection signal is substantially equal to the detection signal.

In the NFC device according to the another aspect, preferably, the controller module is further configured to compare the signal metric of the observed detection signal with the signal metric of the detection signal to determine a signal metric change.

In the NFC device of this further aspect, it is preferred that the controller module is further configured to characterize the signal metric change between detected signals as non-linear or linear to indicate a presence of a second NFC device within the magnetic field when the signal metric change is characterized as substantially non-linear and to indicate an absence of a second NFC device within the magnetic field when the signal metric change is characterized as substantially linear.

Drawings

Embodiments of the present invention are described with reference to the accompanying drawings. In the drawings, like reference numbers can indicate identical or functionally similar elements. Furthermore, the left-most digit or digits of a reference number identify the figure in which the reference number first appears.

Fig. 1 shows a block diagram of NFC according to an exemplary embodiment of the invention;

fig. 2 illustrates a conventional detection mode of operation of a first conventional NFC device for detecting the presence of a second conventional NFC device (prior art);

fig. 3A shows a detection signal for a first NFC-enabled device to detect the presence of a second NFC-enabled device within its magnetic field in accordance with an exemplary embodiment of the present invention.

Fig. 3B shows a first possible variation of a detection signal used by a first NFC-enabled device to detect the presence of a second NFC-enabled device within its magnetic field in accordance with an exemplary embodiment of the present invention;

fig. 3C shows a second possible variation of a detection signal used by a first NFC-enabled device to detect the presence of a second NFC-enabled device within its magnetic field in accordance with an exemplary embodiment of the present invention;

fig. 3D shows a third possible variation of a detection signal used by a first NFC-enabled device to detect the presence of a second NFC-enabled device within its magnetic field in accordance with an exemplary embodiment of the present invention;

FIG. 4 is a flowchart of exemplary operational steps for detecting the presence of an NFC capable device within a magnetic field in an exemplary embodiment in accordance with the present invention;

fig. 5 shows a block diagram of an NFC device that may be used to detect the presence of other NFC capable devices in accordance with an exemplary embodiment of the present invention; and

fig. 6 illustrates a first possible variation of a detection signal used by a first NFC-enabled device to detect a second NFC-enabled device remaining within its magnetic field in an exemplary embodiment in accordance with the invention.

The present invention will be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit or digits in the reference number.

Detailed Description

The following detailed description refers to the accompanying drawings to illustrate exemplary embodiments consistent with this invention. References in the detailed description to "one exemplary embodiment," "an example of an exemplary embodiment," etc., indicate that the exemplary embodiment described may include a particular function, structure, or characteristic, but every exemplary embodiment may not necessarily include the particular function, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same exemplary embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an exemplary embodiment, it is submitted that it is within the knowledge of one skilled in the relevant art to effect such feature, structure, or characteristic in connection with other exemplary embodiments whether or not explicitly described.

The exemplary embodiments described herein are provided for illustrative purposes and are not limiting. Other exemplary embodiments are possible, and changes may be made to these exemplary embodiments without departing from the spirit and scope of the invention. Accordingly, the detailed description is not meant to limit the invention. Rather, the scope of the invention is to be defined only by the claims and their equivalents.

Embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include Read Only Memory (ROM); random Access Memory (RAM); a magnetic disk storage medium; an optical storage medium; a flash memory device; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions herein may be described as performing certain actions. However, it should be understood that such descriptions are merely for convenience and that in fact such actions are the result of execution of firmware, software, routines, instructions, etc. by a computing device, processor, controller or other device.

The following detailed description of exemplary embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the relevant art, readily modify and/or adapt for various applications such exemplary embodiments without undue experimentation and without departing from the spirit and scope of the present invention. Accordingly, such modifications and variations are intended to be included within the meaning and range of equivalents of the exemplary embodiments, in light of the teaching and guidance provided herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings herein.

Although the description of the present invention is in terms of NFC, one of ordinary skill in the relevant art will recognize that the present invention may be applicable to other communications using the near field and/or the far field without departing from the spirit and scope of the present invention. For example, although the present invention is described as using NFC-enabled communication devices, one of ordinary skill in the relevant art will recognize that the functionality of these NFC-enabled communication devices may be adapted to other communication devices using the near field and/or the far field without departing from the spirit and scope of the present invention.

Exemplary Near Field Communication (NFC) Environment

Fig. 1 shows a block diagram of an NFC environment according to an exemplary embodiment of the present invention. The NFC environment 100 provides for wireless communication of information, such as one or more instructions and/or data, between a first NFC device 102 and a second NFC device 104, the NFC devices being sufficiently close to each other. The first NFC device 102 and/or the second NFC device 104 may be implemented as stand-alone devices or as separate devices, or may be incorporated in or coupled to another electrical or host device such as, for example, a mobile telephone, a portable computing device, another computing device (e.g., a personal computer, laptop or desktop computer), a computer peripheral such as a printer, a portable audio and/or video player, a payment system, a ticket writing system (e.g., a parking ticketing system, a bus ticketing system, a train ticketing system or an entrance ticketing system), or in a ticket reading system, toy, game, poster, packaging, advertising material, product inventory detection system, and/or any other suitable electronic device that will be apparent to one of ordinary skill in the relevant art without departing from the spirit and scope of the present invention.

The first NFC device 102 detects the presence of the second NFC device 104 to enable communication of information between the first NFC device 102 and the second NFC device 104. Typically, the first NFC device 102 observes its magnetic field for the presence of the second NFC device 104. The first NFC device 102 observes the change in its magnetic field as the second NFC device enters the magnetic field.

Normal detection mode of operation

Conventionally, a first conventional NFC device operates in a conventional detection mode of operation to detect the presence of a second conventional NFC device. Upon detecting the second conventional NFC device, the first conventional NFC device enters a conventional polling mode of operation to establish communication with the second conventional NFC device.

Fig. 2 illustrates a normal operation detection method of an operation used by a first conventional NFC device to detect the presence of a second conventional NFC device. The first conventional NFC device provides detection pulses having substantially the same amplitude until a change in the amplitude of one of the conventional detection pulses is detected. The amplitude change indicates that the second conventional NFC device has entered the magnetic field provided by the first conventional NFC device. Upon detecting the second conventional NFC device, the first conventional NFC device enters a conventional polling mode of operation to establish communication with the second conventional NFC device.

As shown in diagram 202, the first conventional NFC device provides one or more conventional detection pulses 206.1 through 206.N, each of the conventional detection pulses 206.1 through 206.N being characterized as having substantially the same amplitude (magnitude). For example, the amplitude of the regular detection pulse 206.1 is substantially the same as the amplitude of the regular detection pulse 206.2, and the amplitude of the regular detection pulse 206.2 is substantially the same as the amplitude of the regular detection pulse 206. N. As also shown in diagram 202, after the normal detect pulse 206.N, the first conventional NFC device enters a normal polling mode of operation 208 to establish communication with the second conventional NFC device. An example of a conventional polling mode 208 of operation describes "NFCForum: NFCActive specification: technical specification, NFCForum published on 18/11 2010^TMActivity1.0NFCForum-TS-Activity-1.0 ", the entire contents of which are incorporated herein by reference.

As shown in diagram 204, a first conventional NFC device observes one or more conventional detection pulses 206.1 through 206.N, referred to as one or more observed conventional detection pulses 210.1 through 210. N. One or more of the observed detection pulses 210.1 through 210. (N-1) are characterized as having substantially the same amplitude. The substantially same amplitude of the observed one or more detection pulses 210.1 through 210. (N-1) indicates that there is no second conventional NFC device in the magnetic field. Also as shown in plot 204, the observed detection pulse 210.N is not substantially the same amplitude as the observed detection pulse 210. (N-1). This difference in amplitude indicates (indicates) that a second conventional NFC device entered the magnetic field during the conventional detection pulse 206. N. Thus, a first conventional NFC device may enter a conventional polling mode of operation 208 to establish communication with a second conventional NFC device. The first conventional NFC device continuously observes a conventional polling mode of operation 208, referred to as an observed polling mode of operation 212, to verify that the second conventional NFC device remains within the magnetic field. The conventional detection mode of operation is described more in U.S. patent application No.: 12/446,591, incorporated herein by reference in their entirety.

However, such simple detection of a change in the conventional detection mode is sensitive to a change in the environment. For example, moving the first NFC device around the environment may result in a change in the amplitude of one or more regular detection pulses 206.1 to 210. N. As another example, an object in the environment (e.g., a metal object or other NFC-incapable device as part of an example) entering the magnetic field may cause a change in the amplitude of one or more of the conventional detection pulses 206.1 through 210. N. However, these changes are caused by changes in the environment, not from the second conventional NFC present within the magnetic field. As a matter of course, the first conventional NFC device may incorrectly determine that a second conventional NFC device is present within the magnetic field and enter the conventional polling mode of operation 208 when the second conventional NFC device is not within the magnetic field.

In general, these environmentally generated changes can be characterized as linear. However, the variations produced by additional NFC-enabled devices present within the magnetic field may be characterized as non-linear. For example, other NFC-enabled devices begin to generate or harvest (derivorrivest) energy once the incoming magnetic field causes a non-linear change in the magnetic field. However, the conventional detection mode of operation cannot distinguish between linear and non-linear variations; thus, the conventional detection mode is prone to misinterpret the environmental change as an indication that a second conventional NFC is present within the magnetic field.

Exemplary detection mode of operation

However, the present invention is able to distinguish the difference between linear and non-linear changes, so that the detected pulse changes, which are characterized as linear in the present invention, can be ignored when it is environmental changes. The detection pulse changes characterized as non-linearities in the present invention can be identified as being caused by the presence of another NFC-enabled device within the magnetic field.

Fig. 3A shows a detection signal for a first NFC-enabled device to detect the presence of a second NFC-enabled device within its magnetic field in accordance with an exemplary embodiment of the present invention. Typically, a first NFC-enabled device (e.g., first NFC device 102 as an example) is configured to operate in an initiator mode of operation or a reader mode of operation, while a second NFC-enabled device (e.g., second NFC device 104 as an example) is configured to operate in a target mode of operation or a bookmark mode of operation.

A first NFC-enabled device provides a detection sequence comprising one or more detection signals 302.1 to 302.N to detect the presence of a second NFC-enabled device within its magnetic field. Typically, one or more detection signals 302.1 to 302.N are characterized by substantially the same ramp function. In an exemplary embodiment, the ramp function may approximate a step function or a step function having an increasing magnitude. However, the one or more detection signals 302.1 to 302.N are not limited to ramp functions; one of ordinary skill in the relevant art may implement one or more of the detection signals 302.1 through 302.N using other suitable monotonically increasing and/or decreasing functions without departing from the spirit and scope of the present invention. A first NFC-enabled device may modulate one or more detection signals 302.1 through 302.N on a carrier wave to provide a detection sequence.

The first NFC-enabled device observes the detection sequence to recover one or more observed detection signals 304.1 through 304.N to detect the magnetic field change. The change in the magnetic field may indicate that a second NFC-enabled device may be present within the magnetic field. For example, a first NFC-enabled device may compare one of observed detection signals 304.1 through 304.N to a previously observed detection signal of observed detection signals 304.1 through 304.N to detect a magnetic field change. As another example, a first NFC-enabled device may compare one of the observed detection signals 304.1 through 304.N to a corresponding one of the one or more detection signals 302.1 through 302.N to detect a magnetic field change.

In general, a first NFC-enabled device may observe its magnetic field to change unchanged, linearly, and/or non-linearly. For example, as shown in fig. 3B, each of the observed detection signals 304.1 through 304.N are substantially identical, indicating no change in the magnetic field of the first NFC-enabled device. As another example, also shown in fig. 3B, each observed detected signal 304.1 through 304.N has substantially the same signal envelope (signalengvelope) as their corresponding detected signal or signals 302.1 through 302.N, indicating no change in the magnetic field of the first NFC-enabled device. The absence of a change in the magnetic field as illustrated in these examples of fig. 3B indicates that there is no second NFC-enabled device within the magnetic field of the first NFC-enabled device.

Objects in the environment (e.g., metal objects or other NFC-incapable devices as some examples) may enter the magnetic field of the first NFC-capable device. These objects may cause linear changes in the magnetic field of the first NFC-enabled device. For example, as shown in fig. 3C, each observed detection signal 304.1 to 304. (N-1) is substantially the same, indicating no change in the magnetic field of the first NFC-enabled device. However, observed detection signal 304.N is different from observed detection signals 304.1 through 304. (N-1), indicating a change in the magnetic field of the first NFC-enabled device. As another example, also shown in fig. 3C, each of the observed detection signals 304.1 through 304. (N-1) has substantially the same signal envelope as their corresponding one or more detection signals 302.1 through 302. (N-1), indicating no change in the magnetic field of the first NFC-enabled device. However, the observed detection signal 304.N has a different signal envelope than the detection signal 302.N, indicating the magnetic field variation of the first NFC-enabled device. The magnetic field changes as shown in these examples of fig. 3C may be characterized as linear changes in the magnetic field of the first NFC-enabled device. For example, observed detection signal 304.N is linearly related to detection signal 304.N and/or observed detection signals 304.1 through 304 (N-1). The first NFC-enabled device can recognize that the linear change in the magnetic field is due to an object in the environment entering the magnetic field of the first NFC-enabled device.

Typically, a second NFC-enabled device generates or derives energy from one or more detection signals 302.1 through 302. N. After sufficient energy is obtained from one or more of the detection signals 302.1 to 302.N, a second NFC-enabled device is turned on. The switching on of the second NFC-enabled device, and the harvesting of energy, may cause a non-linear change in the magnetic field of the first NFC-enabled device.

For example, as shown in fig. 3D, each of the observed detection signals 304.1 through 304. (N-1) is substantially the same, indicating no change in the magnetic field of the first NFC-enabled device. However, observed detection signal 304.N is different from observed detection signals 304.1 through 304. (N-1), indicating a change in the magnetic field of the first NFC-enabled device. As another example, also shown in fig. 3D, each of the observed detection signals 304.1 through 304. (N-1) has substantially the same signal envelope as their corresponding one or more detection signals 302.1 through 302. (N-1), indicating no change in the magnetic field of the first NFC-enabled device. However, the observed detection signal 304.N has a different signal envelope than the detection signal 302.N, indicating the magnetic field variation of the first NFC-enabled device. The magnetic field variation as shown in these examples of fig. 3D may be characterized as a non-linear variation in the magnetic field of the first NFC-enabled device. For example, observed detection signal 304.N is non-linearly related to detection signal 302.N and/or observed detection signals 304.1 through 304. (N-1). A first NFC-enabled device is able to recognize that a non-linear change in magnetic field is caused by a second NFC-enabled device entering within its magnetic field.

It should be noted that the linear variation shown in fig. 3C and the non-linear variation shown in fig. 3D are for illustrative purposes only, and those of ordinary skill in the art will recognize that other linear and/or non-linear variations are possible without departing from the spirit and scope of the present invention.

Referring again to fig. 1, upon detecting the presence of the second NFC-enabled device 104 within its magnetic field, the first NFC-enabled device 102 may enter a polling mode (e.g., a conventional polling mode 208 of operation or any other suitable polling mode as would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present invention) to establish communication with the second NFC-enabled device.

By applying the modulated information communication to the first antenna to provide the first information communication 152, the first NFC device 102 modulates its corresponding information onto the first carrier wave and generates a first magnetic field. Once the information is transferred to the second NFC device 104, the first NFC device 102 continues to apply the first carrier without its corresponding information to continue to provide the first communication of information 152. The first NFC device 102 is in sufficient proximity to the second NFC device 104 such that the first information communication 152 is inductively coupled to the second antenna of the second NFC device 104.

The second NFC device 104 generates or obtains energy from the first information communication 152 to recover, process, and/or provide a response to the information. The second NFC device 104 demodulates the first communication 152 to recover and/or process the information. The second NFC device 104 may respond to the information by applying its corresponding information to a first carrier that is inductively coupled to a second antenna to provide a second modulated information communication 154.

The operation of the first NFC device 102 and/or the second NFC device 104 may be described with reference to international standard ISO/IE18092 published on 4/1/2004: 2004 (E), "information technology-telecommunications and information exchange BetWenenSystems-near field communication-interface and protocol (NFCIP-1)", and International Standard ISO/IE21481 published on 1/15/2005: 2005 (E), "information technology-telecommunications and information exchange BetWenens systems-near field communication-interface and protocol-2 (NFCIP-2)".

Although fig. 1 and 3A-3D describe initiator operating mode (initiatormodeoperation) and target operating mode, persons of ordinary skill in the art will recognize that the first NFC device 102 and/or the second NFC device 104 described in fig. 1, and/or the first NFC-enabled device and/or the second NFC-enabled device described in fig. 3A-3D may alternatively be configured to operate in a communicator operating mode (communicationmode) without departing from the spirit and scope of the present invention. These NFC devices and/or NFC-enabled devices are configured to operate in an initiator mode of operation and/or a target mode of operation and are switchable between these modes of operation in a communicator mode of operation.

Method for detecting NFC-enabled devices

Fig. 4 is a flowchart of exemplary operational steps for detecting the presence of an NFC capable device within a magnetic field in an exemplary embodiment in accordance with the present invention. The present invention is not limited to this description of operation. Rather, it will be apparent to those skilled in the art from this disclosure that other operational control flows are within the scope and spirit of the present invention. The following discussion describes the steps in fig. 4.

At step 402, the operational control flow receives a detection signal, such as one of the one or more detection signals 302.1 through 302.N as an example. The operational control flow provides a detection sequence including a detection signal to its environment. For example, the operational control flow may modulate a detection signal with a carrier wave and generate a magnetic field using the modulated detection signal to provide a detection sequence. The detection signal is a monotonically increasing and/or decreasing signal (e.g., a ramp signal as an example) that is modulated onto a carrier.

At step 404, the operational control flow observes the test sequence from 402 to provide an observed test sequence when the test sequence is provided to its environment. The operational control demodulates the detected sequence from 402 to recover an observed detected signal, such as one of the one or more observed detected signals 304.1 through 304.N, as an example.

At step 406, the operational control flow determines a signal metric change (signalmetric change) between the detection signals. For example, the operational control flow may compare one or more signal metrics of the detected signal from step 402 with one or more signal metrics of the observed detected signal from step 404 to provide a signal metric change. As another example, the operational control flow may compare one or more signal metrics of the observed detected signal from step 404 to one or more signal metrics of one or more previously observed detected signals to provide a signal metric change. When the change in signal metric is approximately equal to zero, the operational control flow may return to step 402 to receive another detection signal. Alternatively, when the signal metric change is less than and/or equal to the threshold, the operational control flow may return to step 402. In this alternative, the threshold is used to compensate for signal metric variations that may be attributed to other factors (e.g., generation of the detection sequence of step 406 and/or recovery of the observed detection sequence of step 404 as partial examples) and not to the NFC device present within the magnetic field. For example, the threshold may be used to compensate for linear and/or nonlinear effects that may be attributable to the modulator used to generate the detection sequence of step 406. As another example, the threshold may be used to compensate for linear and/or nonlinear effects that may be attributable to the demodulator used to recover the observed detection sequence of step 404. As yet another example, the threshold may be used to compensate for linear and/or non-linear effects that may be attributable to the communication channel.

When the signal metric change is greater than zero, or greater than a threshold value, the operational control flow determines that an NFC capable device may be present within the magnetic field of step 402 and continues to step 408.

At step 408, the operational control flow characterizes the signal metric change of step 406 as being non-linear or linear. For example, the operational control flow may distinguish the change in the signal metric of step 406 to determine whether it is non-linear or linear. In general, the derivative of a linear function is characterized as being substantially constant. The operational control flow may characterize the change in the signal metric of step 406 as linear when its derivative is substantially constant or as non-linear when its derivative is not substantially constant. Further, the operational control flow may use the derivative as an input to a trigger counting device (e.g., a binary counter as an example). In this alternative, the count of the counting means changes from its present state to another state when the derivative changes. Further, in this alternative, the operational control flow may characterize the change in the signal metric of step 406 as linear when the count of the counting device is less than or equal to a predetermined value, or as non-linear when the count of the counting device is greater than or equal to a predetermined value.

At step 410, the operational control flow characterizes the change in signal metric of step 406 as being caused by a change in the environment. The operational control flow determines that an NFC capable device is not present within the magnetic field of step 402 and returns to step 402 to provide additional detection signals to its environment.

At step 412, the operational control flow characterizes the signal metric change of step 406 as being caused by the presence of the NFC capable device within the magnetic field of step 402.

First exemplary NFC device

Fig. 5 shows a block diagram of an NFC device that may be used to detect the presence of other NFC capable devices in an exemplary embodiment in accordance with the invention. The NFC device 500 may be configured to operate in a detection mode of operation to detect the presence of another NFC-enabled device within its magnetic field. It is noted that fig. 5 only illustrates a detection mode of operation, and those of ordinary skill in the art will recognize that the NFC device 500 may be configured to operate in other modes of operation, such as a point-to-point (P2P) communication mode or a reader/writer (R/W) communication mode, without departing from the spirit and scope of the present invention. The NFC device 500 includes a controller module 502, a modulator module 504, an antenna module 506, and a demodulator module 508. The NFC device 500 may be an exemplary embodiment of the first NFC device 102.

The controller module 502 controls the overall operation and/or configuration of the NFC device 500. In the detection mode of operation, the controller module 502 generates a detection signal 552, such as one of the one or more detection signals 302.1 through 302.N as an example. The detection signal 552 may be a monotonically increasing and/or decreasing function (e.g., a ramp function as an example) or a step function approximating a monotonically increasing and/or decreasing function.

The controller module 502 may generate the detection signal 552 in response to the instructions. The commands may be provided to the controller module 502 from one or more data storage devices, such as one or more contactless transponders, one or more contactless tags, one or more contactless smart cards, any other machine-readable medium apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention, or any combination thereof. Other machine-readable media may include, but are not limited to, Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, as some examples). The controller module 502 may also receive commands from a user interface, such as a touch screen display, an alphanumeric keypad, a microphone, a mouse, a speaker, any other suitable user interface as part of the user interface as would be apparent to one of ordinary skill in the art, without departing from the spirit and scope of the present invention. The controller module 502 may also receive instructions from other electrical devices or host devices coupled with the NFC device 500.

Modulator module 504 modulates sense signal 552 on a carrier wave (e.g., a radio frequency carrier wave having a frequency of about 13.56 mhz) using any suitable analog or digital modulation technique to provide modulated sense signal 554. Suitable analog or digital modulation techniques may include Amplitude Modulation (AM), Frequency Modulation (FM), Phase Modulation (PM), Phase Shift Keying (PSK), Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), Quadrature Amplitude Modulation (QAM), and/or any other suitable modulation technique that will be apparent to one of ordinary skill in the art. In an exemplary embodiment, the modulator module 504 may include a Direct Digital Synthesizer (DDS) under the control of the controller module 502 for generating the detection signal 552. In this exemplary embodiment, modulator module 504 also includes an analog-to-digital converter (ADC) to convert sense signal 552 from a digital representation to an analog representation based on a carrier to provide modulated sense signal 554.

The antenna module 506 applies the modulated detection signal 554 to an inductive coupling element (e.g., a resonant tuned circuit as an example) to generate a magnetic field to provide a detection sequence 556. Antenna module 506 observes detection sequence 556 to provide an observed detection sequence 560.

Demodulator module 508 demodulates detected sequence 558 using any suitable analog or digital modulation technique to provide recovered detected signal 560. Suitable analog or digital modulation techniques may include Amplitude Modulation (AM), Frequency Modulation (FM), Phase Modulation (PM), Phase Shift Keying (PSK), Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), Quadrature Amplitude Modulation (QAM), and/or any other suitable modulation technique that will be apparent to one of ordinary skill in the art.

Controller module 502 may determine one of a plurality of signal metrics for detected signal 552 and/or recovered detected signal 560. The one or more signal metrics may include an average voltage and/or current level (meanvoltageand/orcurrentlevel), an average voltage and/or current level (averagevoltageand/orcurrentlevel), an instantaneous voltage and/or current level, a root mean square voltage and/or current level, an average power (meanpower), an average power (averagepower), an instantaneous power, a root mean square power, a signal envelope, and/or any other suitable signal metric that may be apparent to one of ordinary skill in the art of detecting signal 552 and/or recovered detected signal 560 without departing from the spirit and scope of the present invention.

Controller module 502 may compare one of a plurality of signal metrics of recovered detected signal 560 to one or more previous signal metrics of recovered detected signal 560 to provide a signal metric change. Alternatively, controller module 502 can compare one of the plurality of signal metrics of recovered detected signal 560 to one of the plurality of signal metrics of detected signal 552 to provide a signal metric change.

The controller module 502 may compare the signal metric change to a threshold to determine whether the signal metric change indicates a difference between the signal metrics. The threshold is used to compensate for differences between detected signal 552 and/or recovered detected signal 560 that may be attributable to defects in NFC device 500 (e.g., defects in modulator module 504, antenna module 506, or demodulator module 508 as some examples). For example, defects in demodulator module 508 may cause undesirable attenuation of recovered detection signal 560. This undesirable attenuation of recovered detection signal 560 is not attributable to another NFC-enabled device present within the magnetic field. Thus, when signal metric variation may be attributed to a defect of the NFC device 500, the controller compares the signal metric variation to a threshold value to substantially reduce the likelihood that the controller module will interpret the signal metric variation as being due to another NFC-enabled device.

When the signal metric change is less than or equal to the threshold, the signal metric change indicates no difference between the signal metrics. In this case, any signal metric variation between one of the plurality of signal metrics of recovered detected signal 560 and one of the plurality of signal metrics of detected signal 552 and/or one or more previous signal metrics of recovered detected signal 560 may be attributable to a defect in NFC device 500, rather than the presence of another NFC device within the magnetic field.

The signal metric change indicates a difference between the signal metrics when the signal metric change is greater than a threshold. The controller module 502 analyzes the signal metric change to determine if another NFC capable device is present within the magnetic field. For example, the control module 502 may distinguish a signal metric change to determine whether it is non-linear or linear. The controller module 502 may characterize the signal metric change as linear when its derivative is substantially constant or as non-linear when its derivative is not substantially constant. Further, the controller module 502 may use the derivative as an input to trigger a counting device (e.g., a binary counter as an example). In this alternative, the count of the counting means changes from its present state to another state when the derivative changes. Further, in this alternative, the controller module 502 may characterize the difference from step 406 as linear when the count of the counting device is less than or equal to a predetermined value, or as non-linear when the count of the counting device is greater than or equal to a predetermined value.

Referring again to fig. 3A, upon detecting the presence of a second NFC-enabled device within its magnetic field as described in fig. 3A through 3D, the first NFC-enabled device may continue to provide a detection sequence including one or more detection signals 302.1 through 302.N to verify that the second NFC-enabled device remains within the magnetic field. For example, as shown in fig. 6, a first NFC-enabled device observes a detection sequence to recover one or more observed detection signals 602.1 through 602. N. The first NFC-enabled device compares the respective one or more observed detection signals 602.1 through 602.N with the respective one or more of the one or more detection signals 302.1 through 302.N to detect whether the second NFC-enabled device remains within its magnetic field.

As shown in fig. 6, the observed signal envelopes of detection signals 602.1 through 602 (N-1) are substantially different from the signal envelopes of their corresponding detection signals 302.1 through 302 (N-1). In this case, the second NFC-enabled device continues to generate or obtain energy from one or more detection signals 302.1 through 302. (N-1). Thus, the second NFC-enabled device remains within the magnetic field of the first NFC-enabled device. It should be noted that the difference in signal envelopes of one or more of the detected signals 602.1 through 602 (N-1), as shown in FIG. 6, is for illustrative purposes only, and those of ordinary skill in the art will recognize that other differences in observed signal envelopes of the detected signals 602.1 through 602 (N-1) are possible without departing from the spirit and scope of the present invention.

However, the observed signal envelope of detected signal 602.N is substantially similar to the signal envelope of detected signal 302.N, indicating that the second NFC-enabled device is no longer generating or harvesting energy from detected signal 302. N. Thus, the second NFC-enabled device is not maintained within the magnetic field of the first NFC-enabled device. Thus, as discussed above, a first NFC-enabled device begins detecting the presence of a second NFC-enabled device.

Conclusion

It is to be understood that the detailed description section, and not the abstract section, is intended to be used to interpret the claims. The abstract section may set forth one or more, but not all exemplary embodiments of the invention, and thus, is not intended to limit the invention and the appended claims in any way.

The invention has been described with the aid of functional building blocks illustrating the implementation of specific functions and relationships thereof. The boundaries of these functional building block have been arbitrarily defined for the convenience of the description. Other alternative boundaries may be defined so long as the specific functions and relationships thereof are appropriately performed.

It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims (5)

1. A near field communication device, comprising:

a modulator module configured to modulate the detection signal on a carrier to provide a modulated detection signal;

an antenna module configured to apply the modulated detection signal to an inductive coupling element to generate a magnetic field to provide a detection sequence, and the antenna module observes the detection sequence to provide an observed detection sequence;

a demodulation module configured to demodulate the observed detection sequence to provide an observed detection signal; and

a controller module configured to compare a signal metric of the observed detection signals with a signal metric of the detection signals, or to compare a signal metric of one of the observed detection signals with a signal metric of a previously observed detection signal of the observed detection signals to determine a signal metric change, and

the controller module is further configured to:

indicating the absence of a second near field communication device when the observed detection signal is linearly related to the detection signal or the previously observed detection signal, or when the observed detection signal is substantially equal to the detection signal or the previously observed detection signal, or the change in signal metric between the detection signals is characterized as linear,

a change in the signal metric between the detection signals characterized as non-linear indicates the presence of a second near field communication device.

2. Near field communication device according to claim 1, wherein the detection signal is a monotonically increasing signal.

3. Near field communication device according to claim 1, wherein the detection signal is a ramp signal.

4. Near field communication device according to claim 1, wherein the signal measure of the observed detection signal is a signal envelope of the observed detection signal and the signal measure of the detection signal is a signal envelope of the detection signal, or the signal measure of the observed detection signal is a signal envelope of the observed detection signal and the signal measure of the previously observed detection signal is a signal envelope of the previously observed detection signal.

5. A method of detecting the presence of a near field communication device, comprising:

(a) modulating the detection signal on the carrier wave by the second near field communication device to provide a modulated detection signal;

(b) applying, by the second near field communication device, a modulated detection signal to an inductive coupling element to generate a magnetic field to provide a detection sequence, and observing the detection sequence to provide an observed detection sequence;

(c) demodulating, by the second near field communication device, the observed detection sequence to provide an observed detection signal; and

(d) comparing a signal metric of the observed detection signals to a signal metric of the detection signals, or comparing a signal metric of one of the observed detection signals to a signal metric of a previously observed detection signal of the observed detection signals, to determine a signal metric change, wherein,

the (d) further comprises:

indicating the absence of a second near field communication device when the observed detection signal is linearly related to the detection signal or the previously observed detection signal, or when the observed detection signal is substantially equal to the detection signal or the previously observed detection signal, or the change in signal metric between the detection signals is characterized as linear,

a change in the signal metric between the detection signals characterized as non-linear indicates the presence of a second near field communication device.