Apparatus for high frequency near field communication and inductive charging of a portable electronic device

Abstract

The present invention relates to a device (1) for high-frequency communication and inductive charging of a device, comprising a charging surface (5), at least one charging antenna (6) that emits a magnetic field at a low frequency, and a ferromagnetic material layer (7). The device includes at least one communication antenna (31, 32) and a printed circuit board (2). The communication antenna (31, 32) takes the form of a coil locally surrounding the layer (7) having an axis of symmetry located in a plane parallel to the layer (7). The material of the layer (7) is selected such that it has a sufficiently high imaginary part of permeability at high frequencies to induce leakage perpendicular to the layer on the surface of the layer (7), while maintaining a sufficiently low imaginary part of permeability at low frequencies to allow inductive charging.

Description

Technical Field

[0001] The present invention relates to a device for high-frequency near-field communication, such as NFC, and for inductive charging of portable electronic devices. Background Technology

[0002] More specifically, but not exclusively, the invention applies to inductive chargers for portable electronic devices that are intended to be mounted on a motor vehicle and include high-frequency near-field (i.e., short-range) communication devices to communicate with the portable device once the device has been placed on the resting surface of the inductive charger. Near-field communication is understood to mean communication at frequencies around 13.56 MHz, but the invention applies to any communication at frequencies between 3 MHz and 30 MHz that also allow near-field communication.

[0003] Charging devices that utilize magnetic coupling and allow wireless charging of portable electronic devices such as mobile phones, laptops, touchscreen tablets, digital cameras, or even identity badges are currently experiencing significant growth.

[0004] Typically, a charging device utilizing magnetic coupling includes at least one conductor coil, called the "main antenna," which is connected to the charging module. During the charging of the portable device, the charging module generates a charging signal, which allows a current of varying intensity to be guided in the main antenna over time. The powered main antenna thus creates a variable magnetic field.

[0005] The portable device includes a receiver module containing a conductive coil, referred to as an "auxiliary antenna." When the auxiliary antenna is placed within a variable magnetic field formed by the primary antenna, a current is induced in the auxiliary antenna. This current allows an energy storage device connected to the auxiliary antenna to be charged, thus supplying current to the portable device.

[0006] Users place their portable electronic devices on a charging surface that supports the portable devices. The charging surface also serves to support the portable devices during short-range communication, enabling the portable devices to be charged inductively and to communicate with the vehicle's onboard electronics before and during charging via near-field induction or NFC (near-field communication).

[0007] This short-range wireless communication, typically on the order of a few millimeters, allows vehicles and other devices to download user-specific files contained in portable devices and thus adapt vehicle components based on those files; for example, adjusting the driver's seat position, programming a favorite radio, changing the appearance of the dashboard, or even activating the "E-call" function.

[0008] As is well known, these communication and charging devices include: at least one radio frequency antenna dedicated to inductive charging, referred to as a charging antenna, which is of the WPC type (in English, “Wireless Power Consortium”, i.e., a wireless inductive charging antenna according to the standards of the consortium), allowing inductive charging at low frequencies between 30 and 300 kHz (advantageously, from 100 to 200 kHz); and at least one other antenna for communication at frequencies between 3 MHz and 30 MHz (advantageously, 13.56 MHz), dedicated to this near-field communication.

[0009] It can also involve any other radio frequency antenna for short-range coupling communication between a portable device and a charging device connected to the vehicle's onboard electronics system.

[0010] As is well known, the main WPC charging antenna is centered in the middle of the charging device to align with the auxiliary antenna of the portable device, which itself is also typically located at the center of the device. The NFC antenna is usually arranged around the WPC antenna, always around the periphery of the charging device. Similarly, the NFC antenna of the portable device is also located around the periphery of the back of the portable device, and is therefore positioned facing the NFC antenna of the charging device when the portable device is placed on the charging device, thereby allowing effective NFC communication.

[0011] Reference Figure 1 It illustrates an embodiment based on the closest prior art, wherein the prior art communication and charging device 1a includes: a main printed circuit board 2 for monitoring and controlling charging and / or communication; and at least one power source for at least one main charging antenna (in the... Figure 1 (Not visible in the middle) and used for at least one communication antenna 3a (hereinafter referred to as NFC antenna 3a).

[0012] According to this closest prior art, the at least one NFC antenna 3a is etched onto a second printed circuit board 2a located above the at least one transmitter antenna of the inductive charging device, while being in a plane parallel to the main printed circuit board. This moves the main transmitter antenna away from the auxiliary antenna, which exists in the form of a receiver coil in the portable electronic device placed on the second board 2a, and is detrimental to inductive charging.

[0013] Also shown is connection pin 4, which is in the form of three pins, arranged at the four corners of the main printed circuit board 2 and the second printed circuit board 2a respectively, with essentially the same shape and size, and is rectangular.

[0014] In addition to this major drawback in the field of inductive charging, such devices for inductive charging of portable electronic devices and for near-field communication, according to existing technologies, also have several major drawbacks in the field of NFC communication.

[0015] The first drawback is that the NFC antenna is limited to the area used for inductive charging, allowing it to cover only the central area of ​​the device.

[0016] The second drawback is that NFC communication is primarily established with portable electronic devices where the NFC antenna is located in the center (usually around the secondary receiver antenna for charging).

[0017] The third drawback is that NFC communication is not guaranteed during inductive charging, and the NFC communication antenna is strongly coupled to the at least one inductive charging transmitter antenna.

[0018] The fourth drawback is the high sensitivity to metal in portable electronic devices, which can cause strong impedance mismatch for NFC communication.

[0019] The fifth drawback is unstable communication with electronic devices whose NFC antennas are located in the peripheral area of ​​the device (e.g., around the camera at the longitudinal end portion of these devices).

[0020] The sixth drawback is the limited communication area, where the coverage area is smaller than or equal to the size of the antenna printed on the second printed circuit board.

[0021] Finally, the seventh drawback is that the presence of an antenna on the second printed circuit board reduces charging efficiency due to the greater distance caused by the thickness of the second printed circuit board, which has a copper layer that increases the resistivity in the inductive charging device.

[0022] Furthermore, a major drawback of inductive charging devices is the potential presence of foreign metal objects on the charging surface, which could heat up during the charging of portable electronic devices. If these foreign metal objects are not detected and charging is not stopped, they could potentially cause burns to the user.

[0023] The problem upon which this invention is based is to increase the efficiency of inductive charging for devices used for high-frequency near-field communication and for inductive charging of portable electronic devices, while ensuring uninterrupted near-field communication during inductive charging, and in one improvement, also allowing reliable detection of the presence of foreign metal objects on the charging surface.

[0024] In fact, during near-field communication, magnetic coupling occurs between the at least one inductive charging transmitter antenna and the communication antenna, which degrades the signal-to-noise ratio at the electronic device during communication. This invention proposes to avoid this situation. Summary of the Invention

[0025] Therefore, the present invention relates to an apparatus for high-frequency near-field communication, such as NFC, and for inductive charging of portable electronic devices. The apparatus, on the one hand, includes, for charging: a charging surface for supporting the portable electronic device; and at least one charging transmitter antenna disposed below the charging surface and emitting a magnetic field at a low frequency selected between 30 and 300 kHz, with a ferromagnetic material layer disposed below the at least one charging antenna; and on the other hand, includes, for communication: at least one near-field communication antenna that emits a magnetic field at a high frequency between 3 MHz and 30 MHz. The apparatus includes: a printed circuit board for monitoring and controlling charging and / or communication. The at least one communication antenna and at least one power source are provided for the at least one charging antenna and for the at least one communication antenna. Note that the at least one communication antenna is in the form of at least one communication coil, which is arranged relative to the ferromagnetic material layer such that a portion of the field created by the at least one communication coil passes through the ferromagnetic material layer having a permeability including real and imaginary parts. The material of the ferromagnetic material layer is selected to have a real part greater than 10, wherein at a selected high communication frequency, the ratio between the imaginary and real parts is between 0.05 and 1, and at a selected low frequency, the ratio between the imaginary and real parts is between 0 and 0.5.

[0026] These two ratios allow the imaginary part of the permeability to be high enough relative to the real part to induce leakage that extends perpendicularly to the surface of the ferromagnetic material layer, at least partially, while keeping the imaginary part of the permeability low enough relative to the real part at a selected low frequency to allow for inductive charging of the electronic device.

[0027] For inductive charging of portable electronic devices, the resulting technical advantage is that it brings the charging antenna closer to the charging surface, thereby improving near-field communication and charging efficiency. Due to the elimination of the second printed circuit board carrying the communication antenna, the device thickness is reduced, and there is no longer any need for connecting elements between the main printed circuit board and the second board carrying the communication antenna.

[0028] In the prior art, the coil of the communication antenna, which is flatly located on the second printed circuit board, does not allow for satisfactory coverage around the device. This coil is now eliminated, as is the interconnection between the printed circuit boards and the second printed circuit board, and is replaced by a metal ring forming the coil.

[0029] For near-field communication, coverage can be extended if near-field communication can be established during charging. For example... Figure 5 As shown, in a specific case of the device with two communication antennas according to the invention, the communication coverage is uniform around the device and no longer includes any magnetic field peaks.

[0030] Existing technology specifies that inductive wireless charging should be stopped during high-frequency near-field communication, as the NFC communication antenna is strongly coupled to the at least one inductive charging transmitter antenna. This invention allows this stoppage to be avoided by decoupling one or more charging antennas from one or more communication antennas.

[0031] The excitation of a ferromagnetic material by at least one communication antenna according to the invention allows the guidance of a magnetic field to ensure coverage throughout the central region of the device and to generate a magnetic field oriented vertically relative to the material layer by means of leakage caused by the permeability of the material.

[0032] Permeability characterizes a material's ability to modify its magnetic field (i.e., modify magnetic flux lines). Permeability is defined as a complex number, with its imaginary part indicating the material's ability to leak magnetic fields. The higher this imaginary part is at a given frequency, the greater the leakage will be, and the field lines preferably follow a trajectory through regions of high permeability.

[0033] The choice of the imaginary part of the material's permeability depends on the device (e.g., on the type of communication antenna used) and cannot be reduced to a certain value or a certain range of values. Those skilled in the art possess the skill to know the values ​​for high and low communication frequencies, respectively, for communication and charging, in order to select a ferromagnetic material that has a relatively low imaginary permeability at low charging frequencies, where the layer essentially serves to guide the magnetic flux, and a relatively high imaginary permeability at high communication frequencies, so that magnetic field leakage along the ferromagnetic material is possible.

[0034] This choice represents a trade-off between charging efficiency and near-field communication efficiency. The choice can be made by providing a pre-established curve representing the imaginary part of the permeability as a function of an extended frequency field that includes both low and high frequencies.

[0035] The near-field communication area therefore extends towards the longitudinal end, especially for portable electronic devices equipped with near-field communication antennas. Furthermore, near-field communication becomes more stable during charging of certain electronic devices, such as metal mobile phones.

[0036] Regarding the charging of portable electronic devices, the device according to the invention has a reduced distance between one or more charging antennas and the portable electronic device, which allows for reduced energy loss and increased charging efficiency.

[0037] For illustration, in the prior art device, the distance between the portable device and the charging antenna can be 7 mm, including 1.2 mm for the second plate containing the communication antenna flatly etched on the second printed circuit board. The elimination of the second plate allowed by the device according to the invention thus reduces the distance between the charging antenna and the device from 7 mm to 5.8 mm, and the charging efficiency changes from 65% to 70%.

[0038] Preferably, but in a completely non-limiting manner, the communication coil is locally wrapped around a layer of ferromagnetic material.

[0039] Preferably, the communication coil has an axis of symmetry located in a plane parallel to the ferromagnetic material layer.

[0040] Advantageously, the at least one communication antenna surrounds the end portion of the ferromagnetic material layer. In fact, the magnetic field is adapted to penetrate most of the ferromagnetic material layer.

[0041] Advantageously, the at least one communication antenna includes a portion surrounding a printed circuit board or a portion etched onto the printed circuit board on the surface of the printed circuit board facing the at least one charging antenna, and the at least one charging antenna rests on the surface of a ferromagnetic material layer opposite the printed circuit board.

[0042] Essentially, the ferromagnetic material layer serves to guide the magnetic field when charging at low frequencies and to distribute the magnetic field along the material through leakage when communicating at high frequencies.

[0043] Advantageously, the ratio between the imaginary and real parts of the permeability of the ferromagnetic material layer is between 0 and 0.2 for selected low frequencies and between 0.10 and 0.7 for selected high communication frequencies, with the real part being greater than 100.

[0044] Advantageously, the device has a first gap between the portion of the at least one communication antenna oriented opposite to the printed circuit board and the surface of the ferromagnetic material layer facing the at least one charging antenna, and a second gap between the two respective facing surfaces of the printed circuit board and the ferromagnetic material layer, the ratio of the second gap to the first gap being greater than 6.

[0045] It is highly advantageous that all magnetic field leakage from the ferromagnetic material layer is directed toward the charging surface rather than the printed circuit board. The suggested selection of these gaps helps to direct most of the magnetic field leakage toward the charging surface.

[0046] Advantageously, the device includes at least two communication antennas, wherein a first communication antenna is arranged toward an end portion of the ferromagnetic material layer, and a second communication antenna is arranged toward another end portion opposite to the end portion carrying the first communication antenna.

[0047] This indicates a preferred embodiment of the device according to the invention. The magnetic field is better distributed. The device with two communication antennas also allows for functional variation by having one antenna in resonance while the other is activated.

[0048] Advantageously, at least one of the first or second communication antennas takes the form of a communication coil, which on the one hand is connected to a switch that closes or opens a corresponding power supply circuit—the power supply circuit being connected to a main circuit that includes a power source for communication—and on the other hand includes a resonant implementation component at a selected high frequency, which is connected to a resonant implementation control circuit.

[0049] To optimize communication based on operational data, multiple variations may exist for the activation and / or resonance of the communication antenna.

[0050] Advantageously, the device includes a resonant implementation control circuit shared by the coils of the first communication antenna and the second communication antenna. The resonant implementation control circuit includes inverting logic gates that alternately power the resonant implementation components for the coils of the first communication antenna or the coils of the second communication antenna. The resonant implementation components for each communication antenna include at least one capacitor.

[0051] According to the present invention, two main switches are used in the power supply circuit instead of the three switches used in prior art devices. Inserting an inverting logic gate into the resonant implementation control circuit allows for a single control circuit for both communication antennas and simplifies the device construction.

[0052] Advantageously, the control circuit is connected to each switch of the main circuit, and is either placed in a first position that closes the power supply circuit of one coil while opening the power supply circuit of the other coil, or placed in a second position that closes the power supply circuit of one coil while placing the other coil in resonance, and the third position corresponds to the two switches in the open position.

[0053] The two communication antennas can be active simultaneously, inactive simultaneously, one active while the other is in resonance, or one active while the other is inactive. The specific advantages of each variant will be described later.

[0054] Cleverly, the device also includes

[0055] a. A component for measuring the value of current, voltage, or phase shift between voltage and current at a terminal of at least one of two communication antennas.

[0056] b. A component for comparing the thus measured value with a predetermined value.

[0057] c. A component for determining the presence of a foreign metal object based on the result of the comparison.

[0058] Therefore, by simply adding the components described above, the communication device, which includes two communication antennas, can also be used to detect the presence of foreign metal objects on the charging surface.

[0059] Advantageously, the device includes a third auxiliary communication antenna, which is in the form of a coil and extends perpendicularly to the coil of the at least one communication antenna.

[0060] One or more holes may exist in the coverage at one or more communication antennas. The presence of a third communication antenna serves to fill this or these holes within the coverage. This third auxiliary communication antenna may have a central axis oriented perpendicular to the axis of the antenna or each communication antenna.

[0061] Advantageously, the device includes three charging antennas, each in the form of a charging coil. Two charging coils are spaced apart from each other and abut against the ferromagnetic material layer. A third charging coil spans the two charging coils. The three charging coils form an assembly that is symmetrical about a central axis relative to the intervals extending perpendicular to the ferromagnetic material layer. Attached Figure Description

[0062] Other features and advantages of the invention will become more apparent from the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0063] -[ Figure 1 ]: Figure 1 This is a schematic perspective view of a device for inductive charging of portable electronic devices using NFC-type high-frequency near-field communication based on existing technology.

[0064] -[ Figure 2 ]: Figure 2 This is a schematic representation of a longitudinal cross-sectional view of an apparatus for high-frequency near-field communication of the NFC type and low-frequency inductive charging of a portable electronic device according to an embodiment of the present invention. The communication antenna delivers a magnetic field that leaks through a ferromagnetic material layer perpendicular to the layer opposite to the printed circuit board.

[0065] -[ Figure 3 ]: Figure 3 A comparison of the magnetic field strength along the length of ferromagnetic material layers is shown for implementations in devices according to the invention, respectively unsuitable for and adapted to.

[0066] -[ Figure 4 ]: Figure 4 The graphs showing the imaginary and real parts of the magnetic permeability of the ferromagnetic material layer for implementation in a device according to the invention are illustrated.

[0067] -[ Figure 5 ]: Figure 5 Two curves, representing the coverage around the communication and charging devices according to the prior art and the present invention, are shown along the length of the device.

[0068] -[ Figure 6 ]: Figure 6 The diagram illustrates the magnetic field levels along the length of the device relative to the center of the device for communication and charging, according to both prior art and the present invention. The device according to the invention has only one communication antenna.

[0069] -[ Figure 7 ]: Figure 7 Four embodiments of the communication and charging device according to the present invention, having two near-field communication antennas, are shown, wherein the communication antennas are active, inactive, or resonant, respectively, and four magnetic field curves are associated with one of the four embodiments.

[0070] -[ Figure 8 ]: Figure 8 This illustration shows an embodiment of a power supply and resonant control circuit according to the invention for a communication and charging device having two communication antennas. The first communication antenna may be active, inactive, or in resonance, wherein in the first case, the second communication antenna is in resonance, while in other cases it is active or inactive.

[0071] -[ Figure 9 ]: Figure 9 This is a top view of a first variant of a communication device including two planar communication antennas.

[0072] -[ Figure 10 ]: Figure 10 This is a top view of a second variation of the communication device, wherein the communication antenna does not have an axis of symmetry located in a plane parallel to the ferromagnetic material layer.

[0073] -[ Figure 11 ]: Figure 11 This is a schematic view of an improved device according to the invention, wherein the communication device is capable of detecting the presence of a foreign metal object on the charging surface. Detailed Implementation

[0074] Refer to the combination obtained Figures 2 to 8 And especially Figure 2 and Figure 7 The present invention relates to an apparatus for high-frequency near-field communication (in this example, NFC type) and for inductive charging of portable electronic devices.

[0075] The device includes, on one hand, a charging surface 5 for supporting a portable electronic device (not visible in the figure); and at least one charging transmitter antenna 6 arranged below the charging surface 5 to transmit a magnetic field at a selected low frequency between 30 and 300 kHz (advantageously, between 100 and 200 kHz).

[0076] exist Figure 2 and Figure 7Three charging coils 6 are shown, each implemented as a charging antenna 6, which is not limiting. A ferromagnetic material layer 7 (advantageously, a ferrite rod) is arranged beneath one or more charging antennas 6.

[0077] On the other hand, device 1 includes, for communication purposes, at least one near-field communication antenna 31, 32, which transmits a magnetic field at a frequency between 3 MHz and 30 MHz (advantageously, 13.56 MHz). Figure 2 and Figure 7 Two communication antennas 31 and 32 are shown, which are advantageously in the form of coils and are arranged at correspondingly opposite ends of the ferromagnetic material layer 7. However, this is not limiting; one communication antenna 31 and 32 may be sufficient, or an auxiliary communication antenna 33 may be used (especially in...). Figure 8 (As can be seen) can be used between one or more communication antennas 31, 32, wherein the number of communication antennas 31, 32 can be greater than two.

[0078] Device 1 includes: a printed circuit board 2 for monitoring and controlling charging and / or communication; and at least one power supply 8 for one or more charging antennas 6 and for one or more communication antennas 31, 32. The power supply 8 for the one or more communication antennas 31, 32... Figure 8 It is visible in the middle.

[0079] A shared power source can exist for both charging and communication. In this case, the power source can deliver high-frequency or low-frequency current depending on whether communication or charging is desired. Charging cannot be performed simultaneously with communication unless the power source is dual-source. Alternatively, two separate power sources can exist for both communication and charging.

[0080] According to the present invention, one or more communication antennas 31, 32 take the form of at least one communication coil partially surrounding a ferromagnetic material layer 7. Figure 8 The diagram shows communication coils L1 and L2 used for the first communication antenna 31 and the second communication antenna 32.

[0081] In a preferred embodiment of device 1, antennas 31 and 32 are wound around layer 7 and have an axis of symmetry located in a plane parallel to the ferromagnetic material layer 7, as shown in [the diagram]. Figure 2 and Figure 7 middle.

[0082] However, Figure 2 and Figure 7The preferred embodiment of device 1 shown is by no means limiting. The two antennas 31, 32 can take other forms; for example, antennas 31, 32 can be symmetrical or asymmetrical along an axis located in a plane parallel to layer 7, and they can be symmetrical or asymmetrical with respect to each other along that axis. For example, antennas 31, 32 may not have an axis of symmetry located in a plane parallel to layer 7, which is the case in... Figure 10 As shown, antennas 31 and 32 are wound around layer 7 in an offset manner. Antennas 31 and 32 may also be planar, located in a plane parallel to the ferromagnetic material layer 7.

[0083] However, the key aspect of this invention is that the antennas 31 and 32 are arranged such that some or all of the magnetic field they emit passes through the ferromagnetic material layer 7.

[0084] Thus, a portion (advantageously, the majority or main magnetic field) of the field created by the at least one communication coil passes through the ferromagnetic material layer 7 via this layer 7. Since the ferromagnetic material layer 7 has a permeability comprising a real part Parr and an imaginary part Pari, it is provided in the context of the invention that the ferromagnetic material layer 7 is selected such that the layer 7 has a real part greater than 10, wherein at the selected high frequency, the ratio between the imaginary and real parts is between 0.05 and 1, and at the selected low frequency, the ratio between the imaginary and real parts is between 0 and 0.5.

[0085] This results in high-frequency leakage extending perpendicular to the surface of the ferromagnetic material layer 7. The invention also provides that the ferromagnetic material layer 7 is selected such that the ratio between the imaginary and real parts of layer 7 is between 0 and 0.5 at the aforementioned selected low frequencies, low enough to allow inductive charging of the electronic device without excessive loss.

[0086] Within the capabilities of those skilled in the art, the most suitable ferromagnetic material layer 7 can be selected from the plurality of ferromagnetic material layers 7 for incorporation into the communication and charging device 1 according to the invention. This selection can be made according to conventional experiments or by plotting permeability curves with real and imaginary parts in order to choose the most suitable ferromagnetic material.

[0087] exist Figure 2 In the diagram, the total length of device 1 is marked as l, and follows the vertical axis Y as indicated by the arrow extending from above device 1. It is this total length that will be taken as... Figure 3 The length l on the horizontal axis of the curve is given by the curve. The position of the communication antenna 31 on the vertical axis Y is marked as A.

[0088] Reference Figure 3 The figure shows two curves, CO1 and CO2, representing the magnetic field strength emitted by the ferrite, in amperes per meter, as a function of the frequency that varies along the length of the ferrite, which is a ferromagnetic material layer.

[0089] An increase in the magnetic field strength in the central region of the ferrite (e.g., between 6 and 8 cm) is desirable.

[0090] Curve CO1 indicates the magnetic field strength, which is higher than curve CO2 for lengths less than 5 cm, but not higher for lengths greater than 5 cm. The ferrite corresponding to curve CO1 has not been optimized for implementation of this invention and has a large real part and a small imaginary part at high frequencies.

[0091] Thus, the ferrite corresponding to curve CO1 is only allowed to obtain a small field strength in the central region between 6 and 8 cm, while the so-called optimized ferrite corresponding to curve CO2, which has a large real and imaginary part at high frequencies (e.g., 13.56 MHz), generates a larger magnetic field strength in the central region.

[0092] Not limited thereto, the ferrite optimized for carrying out the present invention has relatively low permeability at low frequencies and relatively high permeability at high frequencies.

[0093] exist Figure 4 The diagram shows the curves of the real part Parr and the imaginary part Pari of the complex permeability Perm comp as a function of the operating frequency F (Hz) in Hertz. The leftmost vertical line indicates the low frequency F WPC (advantageously, 100 kHz) for inductive charging, and the rightmost vertical line indicates the high frequency F NFC (advantageously, 13.56 MHz) for near-field communication.

[0094] As can be seen, at high frequencies, the imaginary part Pari increases, and at these high frequencies, the real part Parr decreases, resulting in higher losses. In the context of this invention, it would be suitable to select a ferrite having a high imaginary part Pari at high frequencies but with a sufficiently high real permeability.

[0095] More specifically, it still refers to Figure 4 The ratio of the imaginary part Par i to the real part Par r of the permeability of the ferromagnetic material layer 7 can be between 0 and 0.2 for the selected low frequency and between 0.10 and 0.7 for the selected high frequency, where the real part Par r can be greater than 100.

[0096] Figure 5 Although still referring to Figure 1 and Figure 2 However, a comparison is shown between the coverage Zcouv Et of the communication device 1 according to the prior art and the coverage Zcouv Inv obtained by the communication device 1 according to the invention. In such... Figure 2In the case of the present invention shown, the communication device 1 includes two communication antennas spaced apart by a length less than the total length of the device 1, and the positions of the two communication antennas 31 and 32 are indicated by the truncation of the vertical dashed line on the length y scale.

[0097] In the existing technology, each of the two peaks corresponds to a corresponding branch of the NFC communication antenna 3a etched on the second printed circuit board 2a that extends laterally in the device 1a, such as... Figure 1 As shown in the image.

[0098] Assuming that the two communication antennas 31 and 32 according to the invention have the same corresponding longitudinal position in the device as one of the transverse branches (not necessarily this case), the communication antennas 31 and 32 can have a larger spacing between them and be more eccentric along the length of the device 1 compared to the transverse branches of the communication antenna 3a.

[0099] The horizontal lines indicate, for the lower horizontal line, the minimum near-field communication threshold Smin NFC, and for the higher horizontal line, the maximum near-field communication threshold Smax NFC. Compared to the coverage area Zcouv Et according to the prior art, the amplitude Champ (A / m) of the magnetic field strength in the coverage area Zcouv Inv obtained by the device 1 according to the invention varies less along the Y-axis along the length of the device 1. In particular, in the case of the invention, the peak value of the magnetic field passing through communication antennas 31 or 2 is not high compared to when passing through the lateral branch of communication antenna 3a. The distribution of the covered magnetic field is more uniform along the length of the device.

[0100] Figure 6 The distribution of the magnetic field strength Champ, created in amperes per meter or A / m based on the dimensions of device 1 (advantageously, the length l of the near-field communication and charging device according to the invention), is shown, and compared with distributions from the prior art. An embodiment of the device according to the invention, in this non-limiting case, is a device with two communication antennas, but the device in this… Figure 6 The image is shown in a partial manner, and the magnetic field originating from the second communication antenna is not shown.

[0101] Point 0 on the scale divided into -10 to +6 corresponds to Figure 2 The position of mark A of the first communication antenna 31 in the diagram. If the length x and... Figure 2 Since the auxiliary passive antenna 33 shown is not taken into consideration, the magnetic field between points 0 and -10 is therefore outside the device, while the magnetic field between points 0 and +6 is inside part of the device.

[0102] In each pair of bars, the leftmost bar relates to the magnetic field Inv created by the device according to the invention, while the rightmost bar is Et created by the device according to the prior art. The reference numerals Inv and Et are given only for the corresponding individual bars, but may be used for all magnetic field bars In obtained by the device according to the invention, or for all magnetic field bars Et obtained by the device according to the prior art.

[0103] The region enclosed by the ellipse or Zcouv shape relates only to the device according to the invention at the first communication antenna 31; in the prior art, this region is not located on top of, for example, the device of the first communication antenna 31. Figure 1 The antenna 3a is covered on the second printed circuit board 2a of the main printed circuit board 2 shown in the figure. It is given that the lateral branches of the antenna 3a are arranged at a certain distance from the corresponding longitudinal end of the device 1a. The reference numeral l is related to the length of the device having a length Y (cm) scale in centimeters on the horizontal axis.

[0104] It is identifiable that the magnetic field obtained by the device according to the invention is always higher than that obtained by the device according to the prior art (with one exception at -1 cm).

[0105] In a purely illustrative context rather than a limiting one, at a current of 300mA, the coverage measured using an ISO-14443 Class 3 reference card according to the prior art is 2 to 3 cm, and according to the present invention it is 4 to 9 cm, thus having a near-field communication coverage that is 2 to 3 times larger than the obtained coverage.

[0106] Especially Figure 2 and Figure 7 As can be seen, one or more communication antennas 31, 32 surround the end portion of the ferromagnetic material layer 7.

[0107] Especially Figure 2 As can be seen, the antenna or each communication antenna 31, 32 includes a portion etched on the printed circuit board 2 on the surface of the printed circuit board 2 facing the at least one charging antenna 6. Alternatively, the antenna or each antenna 31, 32 may include a portion surrounding the printed circuit board 2.

[0108] Regarding one or more inductive charging antennas 6, one or more charging antennas 6 may be placed on the surface of the ferromagnetic material layer 7 opposite to the printed circuit board 2.

[0109] exist Figure 2 and Figure 7 The image shows two charging antennas 6 resting on a ferromagnetic material layer 7, with a third charging antenna 6 resting on top of the aforementioned charging antennas 6. Figure 2In the diagram, the horizontal arrows indicate the path of the magnetic field originating from the first communication antenna 31 in the ferromagnetic material layer 7, and the vertical arrows indicate the magnetic field leakage of the ferromagnetic material layer 7 along the dimension of the layer 7 towards the charging surface 5, which is the length l of the device 1.

[0110] More specifically refer to Figure 2 It is suitable to avoid magnetic field leakage by pointing the magnetic field in the opposite direction to the charging surface 5 (i.e. towards the printed circuit board 2).

[0111] Therefore, the communication and charging device 1 may have: a first gap I1, located between the portion of the antenna or each communication antenna 31, 32 oriented opposite the printed circuit board 2 and the surface of the ferromagnetic material layer 7 facing the at least one charging antenna 6; and a second gap I2, located between the two respective facing surfaces of the printed circuit board 2 and the ferromagnetic material layer 7. The ratio of the second gap I2 to the first gap I1 may be greater than 6, which is not actually... Figure 2 However, this is the preferred option in the case of [the situation described above].

[0112] Reference Figure 2 and Figure 7 The device 1 may include three charging antennas 6, each in the form of a charging coil. Two charging coils 6 can be placed against the ferromagnetic material layer 7 while being separated from each other, and a third charging coil spans across the two charging coils 6.

[0113] The three charging coils 6 can thus form an assembly that is symmetrical about the central axis relative to the spacing that extends perpendicular to the ferromagnetic material layer 7.

[0114] As in Figure 2 and Figure 7 As can be seen, in its preferred embodiment, the device 1 may include at least two communication antennas 31, 32. The first communication antenna 31 may be arranged toward one end portion of the ferromagnetic material layer 7, and the second communication antenna 32 may be arranged toward another end portion opposite to the end portion carrying the first communication antenna 31 (advantageously, at opposite longitudinal ends of the communication and charging device 1).

[0115] exist Figure 2 The diagram shows a ground plane 9 within a printed circuit board 2, wherein the end portion of the printed circuit board 2 does not include the ground plane. An auxiliary passive antenna 33 can be accommodated within the end portion of the printed circuit board 2 excluding the ground plane 9. The length x of the end portion of the printed circuit board 2 excluding the ground plane 9 can be less than one-tenth of the total dimension of the printed circuit board 2 in that dimension (advantageously the length l of the device).

[0116] The printed circuit board 2 can be supported by support members 11 located at a certain distance from each other, forming a discontinuous support for the device 1.

[0117] Especially reference Figure 2 , Figure 7 and Figure 8 The first communication antenna 31 and the second communication antenna 32 can be in the form of corresponding communication coils L1 and L2, with the coil turns extending perpendicular to the plane of the ferromagnetic material layer 7. Figure 2 and Figure 7 The diagram shows three rows of turns, but this is certainly not a limiting factor.

[0118] Reference Figure 7 When the near-field communication and charging device 1 includes two communication antennas 31 and 32, different states can be given to these communication antennas 31 and 32, such as: valid state Act, in which the communication antennas 31 and 32 are powered; invalid state Ou, in which the power supply circuit of the communication antennas 31 and 32 is turned on; and resonant state Res, in which the communication antennas 31 and 32 are placed in resonance.

[0119] Figure 7 Four near-field communication and charging devices 1 with different states for communication antennas 31 and 32 are shown, wherein coverage curves cuv1 to cuv4 are obtained by each of these devices 1 in their respective states. For simplicity, reference numerals are indicated only for the first device 1, but also apply to the other three.

[0120] For the first device 1 ( Figure 7 At the top of the array, the first communication antenna 31 is powered and in an active Act state, while the second communication antenna 32 is in a resonant Res state.

[0121] Obtain the first coverage curve Cuv 1. Keep the second line 32 at resonance, which is in... Figure 7 In the far right, the field strength in the electromagnetic material layer 7 is increased to cover the central region.

[0122] for Figure 7 The second device 1, starting from the top, has a first communication antenna 31 that is powered and in an active state (Act), while the second communication antenna 32 is in an inactive state (Ou), and its power supply circuit is open.

[0123] Obtain the second coverage curve Cuv 2. Place the rightmost second communication antenna 32 in the open-circuit area to eliminate the shadows at the antenna location.

[0124] for Figure 7 The third device 1 from the top has a first communication antenna 31 in resonance Res, while the second communication antenna 32 is powered and in active Act.

[0125] The third coverage curve, Cuv 3, is obtained. Keeping the first communication antenna 31, which is on the far left, at resonance allows for an increase in the field strength in the electromagnetic material layer 7 in order to cover the central region.

[0126] for Figure 7 The fourth device 1 from the top has its first communication antenna 31 in an inactive state (Ou), with its power supply circuit open, while the second communication antenna 32 is powered and in an active state (Act). The fourth coverage curve Cuv 4 is obtained.

[0127] In one improvement to the device 1 according to the invention, and Figure 11 As shown, device 1 also includes:

[0128] a. Component M1, which is used to measure the current value, voltage value, or phase shift between voltage and current at the terminals of at least one of the two communication antennas 31 and 32.

[0129] b. Component M2, which is used to compare the measured value with a predetermined value.

[0130] c. Component M3, which is used to determine the presence of a foreign metal object based on the result of the comparison.

[0131] The previously described components may take the form of software or electronic components integrated into printed circuits and connected to a microprocessor.

[0132] Therefore, through such Figure 7 The configuration of communication antennas 31 and 32 is changed as shown, and the presence of a foreign metal object can be determined by comparing the corresponding parameters at the antenna terminals with predetermined measurements. In fact, the presence of a foreign metal object on the charging surface modifies the electromagnetic field between the two antennas and modifies the following parameters at the terminals of communication antennas 31 and 32:

[0133] a. The voltage at the terminals of a communication antenna that is not active, turned on, or resonant.

[0134] b. Current and / or phase shift at the terminals of an effective communication antenna.

[0135] The pre-implemented measurements can originate from the calibration phase, during which measurements are performed on different types of metal objects placed on the surface of device 1, or advantageously, the pre-implemented measurements are performed at a previous time. Therefore, measurements are implemented dynamically, and any changes in the measurements over time can be detected, indicating the presence of a foreign metal object on the resting surface if the change exceeds a predetermined threshold.

[0136] More specifically refer to Figure 8On the one hand, the corresponding communication coils L1 and L2 of each of the communication antennas 31 and 32 can be connected to switches Q3 and Q4 to close or open the corresponding power supply circuits. The corresponding power supply circuits of the communication coils can be connected in parallel with the main circuit 12, which includes the power supply 8 for communication.

[0137] On the other hand, each communication coil L1, L2 of the communication antennas 31, 32 may include components Q1, C3; Q2, C4 for resonating each respective coil L1, L2 at a selected high frequency, which are connected in parallel with the resonating implementation control circuit 14.

[0138] The main circuit 12 includes an RF adapter circuit, which includes a first capacitor C1 and a resistor R1. It has a branch section that is grounded via a branch including a second capacitor C2, the branch being inserted between the first capacitor C1 and the resistor R1. The main circuit 12 supplies power to the first communication antenna 31 via a first main switch Q3, and as a branch section, supplies power to the second communication antenna 32 via a second main switch Q4.

[0139] The resonant control circuit 14 controls the selective resonance of the first communication antenna 31 or the second communication antenna 32 through the first resonant switch Q1 and the second resonant switch Q2, respectively.

[0140] The labels F and O near switches Q1 to Q4 indicate the corresponding state of the switches, where F indicates a closed circuit or O indicates an open circuit.

[0141] The resonant implementation control circuit 14 includes a first branch, which, as a shunt, supplies power to the second resonant switch Q2 of the coil of the second communication antenna 32 on one hand, and to the first main switch Q3 of the coil of the first communication antenna 31 on the other hand, for control of its open (O) or closed position.

[0142] The resonant implementation control circuit 14 includes a second branch branched from the first branch. As a branch, it supplies power to the first resonant switch Q1 of the coil of the first communication antenna 31 on the one hand, and to the second main switch Q4 of the coil of the second communication antenna 32 on the other hand, for control of its open or closed position.

[0143] The resonant implementation control circuit 14 can be shared by the coils of the first communication antenna 31 and the second communication antenna 32 through its first branch and second branch. The resonant implementation control circuit 14 may include an inverting logic gate 13 in its second branch.

[0144] The inverting logic gate 13 can alternately power the resonant implementation components Q1, C3; Q2, C4 for the coil of the first antenna 31 or the coil of the second communication antenna 32. The resonant implementation components Q1, C3; Q2, C4 for each communication antenna 31, 32 include at least one capacitor C3, C4 shunt from the inductors L1, L2 of the respective coils of the first communication antenna 31 and the second communication antenna 32.

[0145] The control circuit 14 can be connected to each of the main switches Q3 and Q4 of the main circuit 12, and can be either placed in a first position that closes the power supply circuit of one coil while opening the power supply circuit of the other coil, or placed in a second position that closes the power supply circuit of one coil while placing the other coil in resonance.

[0146] However, a third position can be provided corresponding to the two main switches Q3 and Q4 being in the open position, and a fourth position can be provided corresponding to the two main switches Q3 and Q4 being in the closed position.

[0147] like Figure 8 As shown, the near-field communication and charging device may include a third auxiliary communication antenna 33, which takes the form of a coil extending perpendicularly to the coils of the at least one communication antenna 31, 32. This auxiliary communication antenna 33 covers the covered apertures at the first and second communication antennas 31 and 32. The auxiliary communication antenna 33 includes a capacitor C5 and a coil L3, similar to the first and second communication antennas 31 and 32.

[0148] This invention thus wisely allows for overcoming numerous problems from the prior art through the placement of the communication antenna and the technical selection of the ferromagnetic material of the ferrite layer.

Claims

1. A device for high frequency near field communication and for inductive charging of a portable electronic device, the device (1) comprising on the one hand for charging: a charging surface (5) for supporting said portable electronic device; and at least one charging antenna (6) arranged below said charging surface (5) and emitting a magnetic field at a low frequency selected between 30 and 300 kHz, a layer of ferromagnetic material (7) being arranged below said at least one charging antenna (6) and on the other hand for communication comprising at least one near field communication antenna (31, 32) emitting a magnetic field at a high frequency between 3 and 30 MHz, said device (1) comprising: a printed circuit board (2) for monitoring and controlling charging and / or communication; and at least one power supply (8) for said at least one charging antenna (6) and for said at least one communication antenna (31, 32) in the form of at least one communication coil (L1, L2) arranged so that part of the field created by said at least one communication coil passes through said layer of ferromagnetic material (7) having a magnetic permeability comprising a real part (Par r) and an imaginary part (Par i), the material of said layer of ferromagnetic material (7) being selected to have a real part (Parr) greater than 10, wherein at the selected high frequency, the ratio between said imaginary part (Par i) and said real part (Par r) is between 0.05 and 1, and at the selected low frequency, the ratio between said imaginary part (Par i) and said real part (Par r) is between 0 and 0.5, said device being characterized in that it comprises: a) at least two communication antennas (31, 32), wherein a first communication antenna (31) is arranged towards one end portion of said layer of ferromagnetic material (7) and a second communication antenna (32) is arranged towards the other end portion, opposite to the end portion carrying said first communication antenna (31), b) means (M1) for measuring the value of the current, voltage or phase shift between said voltage and said current at the terminals of at least one of said two communication antennas (31, 32), c) means (M2) for comparing said value thus measured with a predetermined value, d) means (M3) for determining the presence of a foreign metallic object on said charging surface based on the result of said comparison.

2. The device (1) as claimed in claim 1, characterized in that Said communication coil locally surrounds said layer of ferromagnetic material (7).

3. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that, Said communication coil has an axis of symmetry lying in a plane parallel to said layer of ferromagnetic material (7).

4. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that Said at least one communication antenna (31, 32) surrounds an end portion of said layer of ferromagnetic material (7).

5. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that, Said at least one communication antenna (31, 32) comprises a portion etched on said printed circuit board (2) around said printed circuit board (2) or on the face of said printed circuit board (2) facing said at least one charging antenna (6), and said at least one charging antenna (6) rests on the face of said layer of ferromagnetic material (7) opposite to said circuit board.

6. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that The ratio of the imaginary part (Par i) to the real part (Par r) of the magnetic permeability of the ferromagnetic material layer (7) is between 0 and 0.2 for a selected low frequency and between 0.10 and 0.7 for a selected high frequency, the real part (Par r) being greater than 100.

7. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that It has a first gap (I1) between a portion of the at least one communication antenna (31, 32) oriented opposite the printed circuit board (2) and a face of the ferromagnetic material layer (7) facing the at least one charging antenna (6), and a second gap (I2) between two respectively facing faces of the printed circuit board (2) and the ferromagnetic material layer (7), the ratio of the second gap (I2) to the first gap (I1) being greater than 6.

8. The apparatus (1) as claimed in claim 7, characterized in that, At least one of the first communication antenna (31) and / or second communication antenna (32) takes the respective form of a communication coil (L1, L2), connected on the one hand to a switch (Q3, Q4) that closes or opens a respective power supply circuit of the communication coil (L1, L2) connected in parallel to a main circuit (12) comprising a power supply (8) for communication, and on the other hand comprising means (Q1, C3; Q2, C4) for the resonance implementation of the respective communication coil (L1, L2) at a selected high frequency, connected in parallel to a resonance implementation control circuit (14).

9. The apparatus (1) as claimed in claim 8, characterized in that, The device (1) comprises a resonance implementation control circuit (14) shared by the communication coils (L1, L2) of the first communication antenna (31) and second communication antenna (32), the resonance implementation control circuit (14) comprising: an inverter logic gate (13) that alternately powers the resonance implementation means (Q1, C3; Q2, C4) of the communication coil of the first communication antenna (31) or of the communication coil of the second communication antenna (32), the resonance implementation means (Q1, C3; Q2, C4) for each communication antenna (31, 32) comprising at least one capacitor.

10. The apparatus (1) as claimed in claim 8, characterized in that, The control circuit (14) is connected to each switch (Q3, Q4) of the main circuit (12) and either places it in a first position that closes the power supply circuit of one of the communication coils (L1, L2) while opening the power supply circuit of the other communication coil, or in a second position that closes the power supply circuit of one of the communication coils (L1, L2) while placing the other communication coil in resonance, a third position corresponding to the two switches (Q3, Q4) being placed in the open position.

11. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that It comprises a third auxiliary communication antenna (33) taking the form of a coil (L3) extending perpendicularly to the communication coils of the at least one communication antenna (31, 32).

12. An apparatus (1) as claimed in any one of claims 1 to 2, characterized in that It comprises three charging antennas (6) each in the form of a charging coil, two charging coils abutting the layer of ferromagnetic material (7) while being spaced apart from each other, the third charging coil straddling the two charging coils, the three charging coils forming an assembly symmetrical with respect to a median axis extending perpendicularly to the layer of ferromagnetic material (7).

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