Method for controlling an NFC device

Abstract

Method for controlling an NFC device. This description relates to a method for controlling a first NFC device (102) comprising an NFC controller (110) connected to an antenna (204), wherein a charging mode of a second, remote NFC device (108) via the antenna (204) is interrupted following detection, by the NFC controller (110), of a change in the impedance of the antenna (204), the interruption being followed by the initiation of communication, via the antenna (204), with a third, remote NFC device (112). Figure for the abstract: Fig. 4

Description

Title of the invention: Method for controlling an NFC device technical field

[0001] This description relates generally to methods for controlling NFC (Near Field Communication) devices and associated NFC devices. Prior art

[0002] NFC communication devices are becoming more and more widespread and are equipping many electronic devices and more particularly mobile phones (smartphones).

[0003] NFC protocols, as defined by the NFC forum, enable communication or charging of NFC devices. However, current devices do not allow these two functions to be implemented efficiently and at a minimum manufacturing cost. Summary of the invention

[0004] There is a need for improvement of NFC devices as well as their control methods.

[0005] An embodiment overcomes all or part of the drawbacks of known NFC processes and devices.

[0006] One embodiment provides a method for controlling a first NFC device comprising an NFC controller connected to an antenna, in which a charging mode of a second remote NFC device by the antenna is interrupted following a detection, by the NFC controller, of a change in the impedance of the antenna, the interruption being followed by the initiation of a communication, via the antenna, with a third remote NFC device.

[0007] One embodiment provides for an NFC device comprising an NFC controller connected to an antenna;

[0008] the NFC controller being configured to interrupt a charging mode of a second remote NFC device via the antenna following detection, by the NFC controller, of a change in antenna impedance;

[0009] the interruption being followed by the initiation of a communication, via the antenna, with a third remote NFC device.

[0010] In one embodiment, the antenna comprises at least two windings in series.

[0011] In one embodiment, said windings comprise one or more turns.

[0012] In one embodiment, the number of turns of one of the windings is between 6 and 8 inclusive.

[0013] In one embodiment, one of said windings defines a first surface and a second winding defines a second surface, the first surface being at least twice as large as the second surface.

[0014] In one embodiment, one of said windings is arranged within another of said windings.

[0015] In one embodiment, one of said windings is arranged outside another of said windings.

[0016] In one embodiment, the antenna comprises two windings; one of said windings being adapted to the NFC load of the second NFC device and the other to NFC detection and communication with the third NFC device.

[0017] In one embodiment, the antenna includes another winding, in series with said two windings, and adapted for NFC loading of a fourth NFC device.

[0018] In one embodiment, following detection, the NFC controller implements an interrogation mode.

[0019] In one embodiment, the charging method is taken up again at the end of the communication.

[0020] One embodiment provides for a mobile phone comprising a device such as described above and configured to implement the process as described above.

[0021] One embodiment provides a system comprising: - a telephone as described above; - a second NFC device; and - a third NFC device.

[0022] In one embodiment, the second device is a stylus.

[0023] In one embodiment, the system includes a fourth NFC device, the the second and fourth NFC devices being NFC devices configured to emit sounds. Brief description of the drawings

[0024] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0025] Fig. 1 represents a schematic view of an example of an NFC communication system;

[0026] [Fig.2] represents a schematic view of an NFC communication system according to one embodiment;

[0027] [Fig.3] represents an embodiment of an antenna of the system of [Fig.2];

[0028] [Fig.4] represents a method for controlling the NFC device of [Fig.2] according to one embodiment;

[0029] [Fig. 5] represents an example of an implementation of the control method of [Fig. 4]; and

[0030] Figure 6 represents another example of an implementation of the control method for Figure 4. Description of embodiments

[0031] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0032] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0033] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0034] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0035] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0036] NFC, or near-field communication, systems use a radio frequency electromagnetic field generated by a device (terminal or reader) to communicate with another device (card). The same device, particularly in the case of mobile phones, can operate in reader mode by generating a field for another device, or in card mode by receiving a field generated by another device. This technology is used for establishing very short-range communications (less than ten centimeters) between two devices.

[0037] This NFC technology also allows an NFC device to charge one or more other NFC devices placed nearby.

[0038] In the present description, we consider the case of a system in which NFC devices are compatible with NFC technology according to the NFC Forum.

[0039] Fig. 1 represents a schematic view of an NFC 100 communication system.

[0040] The NFC system 100 includes an electronic device 130, for example a telephone or smartphone, implementing a first NFC device 102, which includes a first and a second antenna 104, 106. The system also includes, for example, a second NFC device 108, for example a stylus which is configured, for example, to be inserted into the smartphone 130. The system 100 also includes, for example, a third NFC device 112 external to the first device 102 or to the electronic device 130.

[0041] The first device 102 includes for example two NFC controllers 110, 114 connected, preferably connected, respectively to the antenna 106 and 104 by one or more impedance matching circuits -not illustrated-.

[0042] The antenna 104 comprises, for example, one or more turns whose shape is adapted to concentrate the electromagnetic field towards the second device 108.

[0043] The antenna 106 includes, for example, one or more turns whose shape is adapted to detect and communicate with the third device 112 when it enters the near field of interaction provided for by the NFC protocol.

[0044] An electromagnetic field at 13.56 MHz is used between the first and third NFC devices to obtain NFC communication with, for example, a legacy mode, either in reader mode or card mode.

[0045] The second NFC device 108 is charged, at the same frequency, via the antenna 104, with the second NFC device 108 in listener mode and the NFC controller 114 in poller mode. The polling mode consists of emitting periodic bursts of electromagnetic field.

[0046] The example in [Fig.1], the fact that there is an NFC controller per antenna, allows the second NFC device to be charged and at the same time detect and then communicate with the third NFC device 112. However, this example is expensive to manufacture.

[0047] It is possible to consider using only one NFC controller instead of controllers 110 and 114 and only one antenna. However, in this case, detection of other NFC objects cannot be implemented during charging mode. In this case, alternating charging and remote device search phases could be considered. However, this reduces charging efficiency.

[0048] The described embodiments provide a method for controlling the first NFC device (102) comprising an NFC controller connected to an antenna, wherein a charging mode of the second remote NFC device via the antenna is interrupted following detection, by the NFC controller, of a change in impedance of the antenna, the interruption being followed by the initiation of a communication, via the antenna, with the third remote device.

[0049] This allows the third remote device to be detected while the second device is being charged. The efficiency of charging and detection is not degraded compared to the example in [Fig. 1], while also saving on component costs.

[0050] Fig. 2 represents a schematic view of an NFC 200 communication system according to one embodiment.

[0051] The NFC 200 system is similar to the 100 system of [Fig.1] except that the first NFC device 102 includes a single NFC antenna 204 instead of the first and second antennas 104, 106. The first device 102 of [Fig.2] further includes only a single NFC controller 110 connected, preferably connected, to the antenna 204 by an impedance matching circuit -not shown-.

[0052] The antenna 204 is configured to cover part of the NFC device 108 sensitive to the NFC field and also extends more widely within the device 130 to be able to be used for the detection of the remote NFC device 112.

[0053] In the illustrated example, a fourth, optional NFC device 206 is part of the system 200. This NFC device 206 is arranged, for example, within the device 206 and has an NFC-sensitive portion superimposed on a portion of the antenna 204 to enable charging. In this case, the NFC devices 108 and 206 are, for example, NFC devices configured to emit sounds, such as earphones (also known as earbuds) or a stylus and earphone.

[0054] The example in [Fig.2] allows the third remote device 112 to be detected while charging the second device 108 and the fourth device 206, with the same performance as the case in [Fig.1] but at a lower production cost.

[0055] Figure 3 represents an embodiment of an antenna of the system of Figure 2. More particularly, Figure 3 represents antenna 204 in the case where only the NFC device 108 is present; antenna 204 of Figure 3 does not apply as such in the case where the optional device 206 is present.

[0056] In the illustrated example, the antenna 204 comprises at least two series windings, 304 and 306. Winding 304 is connected by one terminal to a connection pad, and winding 306 is connected by another terminal to a different connection pad. Winding 304 has 6 turns, and winding 306 has 2 turns. Winding 304 is positioned to overlap device 108. The shape of winding 304 is more compact than the shape of winding 306. This allows for local optimization and enhancement of the electromagnetic field at device 108 when the device is thin, for example, in the case of a stylus. The more elongated shape of winding 306 allows for greater sensitivity to the electromagnetic field of a distant NFC device, for example, to facilitate its detection.

[0057] The number of turns is, for example, between 1 and 10 inclusive. In one example, the number of turns in the windings could be chosen between 6 and 8 inclusive to locally focus the intensity of the electromagnetic field. However, it is advisable to keep the number of turns below 10 to avoid resonance effects, which are undesirable.

[0058] In the illustrated example, winding 306 defines a first surface and winding 304 defines a second surface. The term "surface" refers to the area defined within the outermost turn of the windings. In one example, the first surface is at least twice as large as the second surface. The area of ​​the first surface is, for example, greater than 200 mm² and the area of ​​the second surface less than 100 mm². Having a winding with a smaller area prevents disturbance to the winding with the larger area.

[0059] In the illustrated example, winding 304 is arranged within winding 306 and in the same plane. In this case, it is necessary to verify that their connection implies a current flowing through them in the same direction so that the electromagnetic fields do not cancel each other out.

[0060] In another example not shown, winding 304 is arranged outside winding 306. In this case, the direction of the current is not necessarily the same between the two windings.

[0061] Winding 304 is adapted to the load of the NFC device 108 and winding 306 to NFC communication with the NFC device 112.

[0062] The winding 304 is arranged to cover the NFC antenna of the device 108 as much as possible, which in addition to increasing the coupling between the two antennas, prevents the device 108 from being detected when communication is implemented with the device 112 via the winding 306.

[0063] The advantage of having a winding 306 larger than the winding 304 is that it prevents the device 108 from masking the detection of the device 112 while ensuring the efficiency of the loading with the smaller winding 304.

[0064] In the example not shown, where a fourth NFC device 206 is present in the system 200, then an additional winding is provided in the antenna 204, for example, of a shape similar to the winding 304, but arranged to overlap with the part of the device 206 that is sensitive to the NFC charge. This additional winding is, for example, connected in series or in parallel with the windings 304 and 306. In this case, the additional winding can be arranged inside or outside the winding 306.

[0065] Not illustrated, regions comprising ferrite are arranged for example between the antenna 204 and the rest of the apparatus 130 in order to limit electromagnetic interactions.

[0066] Fig. 4 represents a method for controlling the NFC device of Fig. 2 according to one embodiment.

[0067] In a step 402 (Charging NFC device(s)), the NFC controller 110 is in a charging mode to charge the device 108.

[0068] In step 404 (Detect antenna impedance change while charging), which is implemented, for example, simultaneously with step 402, the NFC controller 110 is configured to analyze the impedance variations of antenna 204. In this example, a protocol called Foreign Object Detection (FOD) can be used. If an impedance variation is detected, then step 406 (NFC device detected?) is implemented. In step 406, the NFC controller 110 implements a polling mode if an NFC card is nearby, and an Electrical Field Detection (EFD) mode if an NFC device in card or reader mode is recognized, for example, device 112 (branch Y). Then step 408 (Stop charging) is implemented. For example, an anti-collision process is implemented at that time to verify that there is only one card nearby.

[0069] If an NFC device in card or reader mode is not recognized (branch N), for example due to the absence of an NFC device nearby, then step 402 is implemented.

[0070] In step 408, the charging mode of device 108 is interrupted.

[0071] In a step 410 (Initiate communication with tag or reader) which is put in At the same time as or following step 408, a legacy mode is implemented by the NFC controller 110 for communication between device 112 via antenna 204 and more specifically via winding 306. In one example, low power detection is used by the legacy mode (LPTD, Low Power Tag Detection).

[0072] Figure 5 represents an example of an implementation of the control method of Figure 4. More particularly, the example in Figure 5 describes a method of implementing the detection of the impedance change.

[0073] Impedance change detection involves, for example, online and quadrature measurements of the signal received by the antenna. Calibration may also be performed before the measurements to define one or more thresholds. When the threshold is crossed, an impedance change is detected. In one example, the threshold is stored in a memory, for example non-volatile, of the device 130.

[0074] In the example shown, the amplitude of the antenna impedance is expressed in volts as a function of time (Time). Before a time tl (when the impedance changes), the impedance is relatively stable at its nominal value VNom. Between time tl and a At a later time t2 (Transition), the amplitude decreases, for example, linearly until it reaches a threshold at VMin, then remains stable at this level VMin. From time t2 onwards, a change in impedance is detected (Impedance Change). In this example, the threshold VMin is a percentage of the nominal value obtained by calibration.

[0075] Figure 6 represents another example of an implementation of the control method of Figure 4. More specifically, the example in Figure 6 describes another way of implementing impedance change detection.

[0076] The example in [Fig. 6] is similar to that in [Fig. 5] except that the threshold is a voltage VMax that is higher than the nominal voltage VN0M. In one example, the threshold VMax is a percentage of the nominal value obtained by calibration. Between time t1 and time t2 (Transition), the amplitude rises, for example, linearly until it reaches the threshold at VMax and then remains stable at this level VMax. From time t2 onwards, a change in impedance is detected (Impedance Change).

[0077] When communication with device 112 is completed, controller 110 again implements step 402 with the load of device 108 (or even 206 when it is present).

[0078] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to them. In particular, the method of [Fig. 4] also applies, for example, to the case where a fourth NFC 206 device is used. In this case, those skilled in the art will also stop the charging of device 206 if communication is established with device 112.

[0079] Finally, the practical implementation of the described embodiments and variants is within the grasp of a person skilled in the art, based on the functional specifications given above. In particular, regarding the type of communication or load implemented by the controller 110 through the antenna 204, the modulation used is, for example, type A, B, Felica, or type V. A person skilled in the art will choose, for example, between these types to avoid interfering with the other infrastructures of system 200.

Claims

Demands

1. Mobile phone (102) comprising an NFC controller (110) connected to an antenna (204); the NFC controller (110) being configured to interrupt a charging mode of a second remote NFC device (108) by the antenna (204) following a detection, by the NFC controller (110), of a change in impedance of the antenna (204); the interruption being followed by the initiation of a communication, via the antenna (204), with a third remote NFC device (112); the antenna (204) comprising at least two windings (304, 306) in series.

2. Telephone according to claim 1, wherein said windings (304, 306) comprise one or more turns.

3. Telephone according to claim 2, wherein the number of turns of one of the windings is between 6 and 8 inclusive.

4. Telephone according to any one of claims 1 to 3, wherein one of said windings (306) defines a first surface and a second winding (304) defines a second surface, the first surface being at least twice as large as the second surface.

5. Telephone according to any one of claims 1 to 4, wherein one of said windings (304) is arranged within another of said windings (306).

6. Telephone according to any one of claims 1 to 4, wherein one of said windings is arranged outside another of said windings.

7. Telephone according to any one of claims 1 to 6 wherein the antenna (204) comprises two windings; one of said windings (304) being adapted for the NFC charging of the second NFC device (108) and the other (306) for NFC detection and communication with the third NFC device (112).

8. Telephone according to claim 7, wherein the antenna (204) comprises another winding, in series with said two windings (304, 306), and adapted for NFC loading of a fourth NFC device (206).

9.

10.

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13.

14. Telephone according to any one of claims 1 to 8, wherein following detection, the NFC controller (110) implements a polling mode. A telephone according to any one of claims 1 to 9, wherein the charging mode is resumed at the end of the call. A method for controlling a telephone (102) according to any one of claims 1 to 10, wherein the interruption is followed by the initiation of a call, via the antenna (204), with a third remote NFC device (112). System comprising: - a telephone according to any one of claims 1 to 11; - a second NFC device (108); and - a third NFC device (112). System according to the preceding claim, wherein the second device is a stylus. System according to claim 12 or 13, the system comprising a fourth NFC device (206), the second and fourth NFC devices (108, 206) being NFC devices configured to emit sounds.

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