METHOD FOR DETECTING AN OBJECT TO BE LOADED ONTO A LOADING DEVICE AND ASSOCIATED LOADING DEVICE

Abstract

The invention relates to a method for detecting an object to be charged (P) on a charging surface (S) of a charging device (D), said device (D) comprising at least three near-field communication antennas (A0, A1, A2), two antennas (A1, A2) being located at one end (E1, E2) of the device, and a third antenna (A0) being located between the two antennas. The method is characterized in that it comprises: a) Calculating an intensity (I0, I1, I2) circulating in each of the antennas, b) Calculating an intensity variation (ΔI) between the three antennas, c) Comparing said variation with a predetermined intensity variation threshold value (S2), d) Detecting an object to be charged (P) on the surface (S) of the charging device (D) based on the result of the comparison. Figure for the abstract: Fig. 4

Description

Title of the invention: METHOD FOR DETECTING AN OBJECT TO BE LOADED ONTO A LOADING DEVICE AND ASSOCIATED LOADING DEVICE technical field

[0001] The field of the invention is the field of magnetic induction charging devices. In particular, the invention relates to a method for detecting an object to be charged located near a magnetic induction charging device and an associated charging device. Previous technique

[0002] Magnetic induction charging technology is implemented in a system comprising a wireless charging device and a rechargeable battery to be charged in a mobile terminal such as, for example, a user's portable device, like a mobile phone. The charging device includes a transmitting coil. The rechargeable battery includes a receiving coil to be charged. When the transmitting coil and the receiving coil are positioned opposite each other, variations in the magnetic field generated by the transmitting coil induce the flow of an electric current in the receiving coil, which charges the rechargeable battery.

[0003] The inductive charging technology meets the requirements of a standard, in this case the “Qi ®” standard of the “Wireless Power Consortium” also known as the WPC standard.

[0004] In order to detect the presence of an electric accumulator comprising a receiving coil located opposite the transmitting coil of the electric charging device, currently three steps are implemented.

[0005] In a first step, prior art methods seek to detect the presence of an object located opposite the electrical charging device. To this end, electrical pulses, also called "pings," are sent at the charging frequency via the transmitting coil of the electrical charging device to the receiving coil. A "ping" is a continuous signal exhibiting periodic oscillations, for example with a period of 300 ms and an oscillation duration of 5 to 20 ms. The voltage or impedance across the terminals of the transmitting coil is observed. If a change in the voltage across the terminals of the transmitting coil or in the impedance of the transmitting coil is detected, then an object is present opposite the transmitting coil.

[0006] The detected object can be either a parasitic object or a mobile device such as a A mobile phone equipped with an inductive charging coil is used. In a second step, digital communication is established with the detected object to identify its nature. More specifically, this second step seeks to determine if the detected object contains an inductive charging coil in order to charge it. This communication is achieved by modulating the voltage amplitude of the transmitting coil.

[0007] When digital communication is established between the transmitting coil and the receiving coil of the detected object, a third step begins. This third step electrically charges the receiving coil of the detected object.

[0008] However, when the vehicle, equipped with a hands-free access device, enters a so-called "key search" mode, it emits radio frequency waves at a frequency of 125 kHz in order to locate the hands-free access device (badge or mobile phone) around or inside the vehicle. In order to avoid any electromagnetic interference that could affect the location, the mobile phone charging process and all emissions at the charging frequency, i.e., between 110 and 148 kHz, are stopped. This also includes preventing the transmission of a "ping" to detect the presence of the phone on the charging surface.

[0009] Thus, during the badge location process, it is not possible to detect the presence of the mobile phone on the charging surface using the "ping".

[0010] Another method known in the prior art is to use NFC (Near Field Communication) antenna(s) located in the inductive charger to detect the presence of the battery. The method consists of emitting signals at a fixed frequency of 13.56 MHz. If a battery is located near an NFC antenna, then the impedance and / or current consumption of said NFC antenna changes.

[0011] However, this method is not robust and cannot detect certain small receiving coils. This process leads to false detections of the absence of a phone on the charging surface when it may have simply moved on the surface.

[0012] There is indeed a strong disparity in components between the different types and brands of phones which makes it impossible to use a single impedance threshold for all phones from which it can be concluded that the phone is no longer present on the charging surface.

[0013] Ambient temperature also impacts impedance measurement.

[0014] One solution would be to calibrate the current variation measured for each NFC antenna when a mobile phone is removed from the charging surface, and to do this for each type of mobile phone at all temperatures. This process is obviously time-consuming and does not take into account the aging of the parts which also impacts the measured impedance value.

[0015] It therefore seems impossible to reliably and robustly detect the presence or absence of a mobile phone on a charging surface by comparing the impedance measurement of an NFC coil to a predetermined threshold calibrated beforehand.

[0016] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above, by proposing a method for detecting an electric accumulator of the type of user portable equipment, on the charging surface of an inductive charging device, allowing the detection of any type of portable equipment in a reliable and robust manner. Description of the invention

[0017] The invention relates to a method for detecting an object to be loaded onto a charging surface of a charging device, said device comprising at least three near-field communication antennas, two antennas being located at one end of the device, and a third antenna being located between the two antennas, the method being characterized in that it comprises: a. Determining the current intensity flowing through each of the antennas, b. Calculating the variation in intensity between the three antennas, c. Comparison of said variation with a predetermined threshold value for intensity variation, d. The detection of an object to be loaded onto the surface of the charging device based on the result of the comparison.

[0018] In an improvement, the method is triggered based on a result of a comparison between an intensity determination circulating in the third antenna with a predetermined value.

[0019] Preferably, the calculation of a variation in intensity between the three antennas takes the following form:

[0020] ||^-1| - x 100

[0021] With:

[0022] 10: current flowing in the third antenna in mA

[0023] It: intensity circulating in the first antenna in mA

[0024] 12: current flowing in the second antenna mA

[0025] The invention also relates to a device for charging an object to be loaded comprising at least three near-field communication antennas, two antennas being located at one end of the device, and a third antenna being located between the two antennas, said device being characterized in that it comprises: a. Means of determining the intensity circulating in each of the antennas, b. Means of calculating the variation in intensity between the three antennas, c. Means of comparison between said variation and a threshold value of variation of predetermined intensity, d. Means of detecting an object to be loaded onto the surface of the loading device based on the result of the comparison.

[0026] In the improvement, the device further comprises second means for comparing an intensity circulating in the third antenna with a predetermined value

[0027] The invention also relates to any computer program product comprising program code instructions for executing the steps of the process according to any of the characteristics listed above when said program is executed on a computer.

[0028] Finally, the invention applies to any motor vehicle comprising a charging device according to any of the characteristics listed above. Brief description of the drawings

[0029] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0030] [Fig.1]: [Fig.1] is a schematic representation of a charging device according to the invention,

[0031] [Fig.2]: [Fig.2] is an electronic diagram of the charging device according to the invention,

[0032] [Fig.3]: [Fig.3] illustrates nine test configurations of the detection method according to the invention, in which the object to be charged, more precisely the mobile phone, is placed in nine different positions on the charging surface of the charging device,

[0033] [Fig.4]: [Fig.4] is a flowchart illustrating the charging process according to the invention. Description of the implementation methods

[0034] The charging device D according to the invention is illustrated in [Fig. 1]. It comprises an inductive charging antenna, not shown for clarity in [Fig. 1], capable of inductively charging a user's portable device P, such as a mobile phone P, once the latter is placed on the charging surface S of said device. This is known from the prior art.

[0035] According to the invention, the device D is also equipped with at least three antennas A0, A1, A2 for near-field communication, also called NFC "Near Field Communication". The NFC antennas A0, A1, A3 are suitable, for example, for communication communicate with the portable equipment P if the latter is also equipped with a near field communication antenna.

[0036] Near field communication is 13.56 MHz communication.

[0037] The charging device D also includes a microprocessor and a memory (not shown) included in a central unit 10 electronically connected to the charging antenna and the NFC communication antennas in order to manage inductive charging, to transmit and receive data by NFC communication and to perform the various stages of the detection process according to the invention as will be described below.

[0038] In the example illustrated in [Fig.1], the load device D is presented in an illustrative and in no way limiting manner in the form of a parallelepiped, whose length is parallel to a longitudinal axis y of an orthonormal frame (O, x, y, z), the width is parallel to a transverse axis x, and the height is parallel to a vertical axis z of said frame.

[0039] The device D comprises two edges each located at one end El, E2 of the charging device along the longitudinal axis y.

[0040] According to the invention, two NFC communication antennas, Al, A2 are each located at one end El, E2 of the device D.

[0041] As illustrated in [Fig.1], a first antenna Al is wound along the transverse axis x around the first end El, and a second antenna A2 is wound along the transverse axis x around the second end E2.

[0042] A third antenna A0 is located between the first and second antennas Al, A2. The windings of the third antenna A0 are, for example, planar, located in a plane parallel to the plane (O, x, y) itself parallel to the charging surface S.

[0043] The windings of the third antenna A0 are, for example, but in no way limitingly, rectangular in shape.

[0044] As illustrated for the third antenna A0 in [Fig.2], each antenna A0, A1, A2 is connected to the central unit 10 via a circuit comprising various resistors RI, R2, various capacitances Cl, C2, C3, C4, C5, C6 and various inductances L1, L2, connected in parallel which constitute: a. an electromagnetic emission filter circuit, b. an impedance matching circuit, and c. an antenna quality factor control circuit. This type of circuit is known to those skilled in the art and will not be described in further detail here.

[0045] According to the invention, the charging device D is also suitable for: a. determine a current intensity or a representative value of impedance 10, II, 12 across the terminals of each of the antennas A0, Al, A2, b. Calculate the variation in intensity AI between the three antennas AO, Al, A2, c. compare said AI variation with a pre-defined intensity variation threshold value determined S2; d. detect an object to be loaded P onto the surface S of the loading device D according to the result of the comparison.

[0046] To this end, device D comprises; a. means for determining an intensity or a representative value of impedance Ml across the terminals of each of the antennas, b. means of calculating the variation in intensity M2 between the three antennas, c. means of comparison M3 between said variation with a threshold value of variation of predetermined intensity S2; d. means of detecting M4 of an object to be loaded onto the surface of the loading device according to the result of the comparison.

[0047] In an improvement of the invention, the device D is further able to compare an intensity or a representative value of impedance of the third antenna AO with a predetermined value SI.

[0048] In this improvement, the device further includes second means of comparing M5 an intensity value or a representative impedance value of the third antenna with a predetermined value SI.

[0049] The means for determining an intensity or a representative value of impedance M1, the means for calculating a variation in intensity M2 between the three antennas A0, A1, A2, the means for comparison M3 and the means for detection M4, as well as the second means for comparison M5, are presented for example in software form, and are included in the central unit 10.

[0050] The means for calculating a variation in intensity M2 between the three antennas A0, Al, A2 can use any mathematical formula allowing the evaluation of a global variation in intensity on the three antennas A0, Al, A2.

[0051] Preferably, the variation in intensity AI (%) is calculated as follows:

[0052] [Math.l] A / = ||^-1| -1§-1|| x 100

[0053] With

[0054] 10: intensity or representative value of the impedance of the third antenna in mA,

[0055] It: intensity or representative value of the impedance of the first antenna in mA,

[0056] 12: intensity or representative value of the impedance of the second antenna in mA.

[0057] As explained by the mathematical formula below (see [Math 2]), the current flowing through an antenna is indeed directly related to the impedance of said antenna, by the value of the supply voltage of the NFC transmitter, which is constant. Therefore, the current value flowing through each antenna is representative of the impedance value of said antenna.

[0058] The intensity or representative value of the impedance of an antenna Ai is calculated as follows:

[0059] [Math.2] li = — |zd

[0060] With:

[0061] V: NFC transmitter supply voltage in Volts, default value of 3.3 volts,

[0062] Zi: Value of the impedance of the antenna Ai measured at the terminals of the NFC transmitter, it varies according to the antenna connected to the transmitter, because there is always only one antenna powered at a time.

[0063] When no phone P is in front of the antenna Ai, the NFC transmitter being adapted to resonate at the near field communication frequency i.e. F=13.56 MHz, the value of the impedance of the antenna Ai is then large, and therefore the representative value of the impedance li is small.

[0064] Conversely, when a mobile phone P (or any metallic object) is in front of the antenna Ai, there is then a decrease in the value of the impedance Zi at the resonance frequency F and the representative value of the impedance li is then large.

[0065] The variation in intensity AI thus calculated is a value between a minimum value when the surface S is not occupied by a mobile phone P and a maximum value when a mobile phone P is placed on the charging surface S.

[0066] The comparison means M3 are suitable for comparing the intensity variation AI to a predetermined intensity variation threshold value S2, above which it can be concluded that a mobile phone P is present on the charging surface S. For example, considering the values ​​in the table below (see table), the threshold can be set at S2=8% for the same mobile phone P, and then extrapolated to several mobile phones P.

[0067] To implement the improvement of the invention, the device measures (as will be described below) the intensity of the third antenna A0, then compares this intensity to a predetermined threshold SI which makes it possible to determine whether or not there is a phone placed on the charging surface S.

[0068] The detection method, illustrated in [Fig.4], will now be described.

[0069] During a first step El, the intensities or representative values ​​of the im The pedances 10, II, 12 of the three antennas A0, Al, A2 are determined.

[0070] During a second step E2, the variation in intensity AI between the three antennas A0, Al, A2 is calculated according to the formula described previously (cf. [Math 1]).

[0071] In a third step E3, the intensity variation AI thus calculated is compared to a predetermined intensity variation threshold value S2, above which it is considered that an object to be charged, in this case a mobile phone P, is on the charging surface S.

[0072] If the intensity variation AI is greater than this threshold S2, then it is considered that a mobile phone P is on the charging surface S (step E4a).

[0073] If the AI ​​intensity variation is less than this threshold S2, then it is considered that no mobile phone P is on the charging surface S (step E4b).

[0074] This is illustrated in [Fig.3]. In [Fig.3] nine possible configurations CFI, CF2...CF9 of positioning a mobile phone P on the charging surface S of the charging device D are shown.

[0075] The table below shows the intensities 10, II, 12 of the three antennas A0, Al, A2 as well as the variation of intensity AI for these nine configurations CF1...CF9. [Tables 1] Configuration 10 (mA) Il (mA) 12 (mA) AI (%) CFI 100 84.8 71.2 22.5 CF2 79.4 72 66.4 9.3 CF3 78.6 72 66 9.9 CF4 80 66.4 72.2 9.7 CF5 81 66.8 71.8 8.4 CF6 100 75.2 69.6 10.7 CF7 99.2 74 68.4 10.9 CF8 94.4 72.8 68.4 8.3 CF9 100 79.2 69.2 18.2

[0076] It is clear that the presence of the mobile phone P on the charging surface S induces a variation in intensity AI greater than 8%.

[0077] Of course, the table above can be repeated for different types of mobile phones P in order to fix a single threshold S2 common to all mobile phones P.

[0078] The applicant has indeed observed that the threshold value S2 above which the presence of a mobile phone P can be detected varies little depending on the types of mobile phones P, which is a significant advantage compared to the prior art.

[0079] Thus, it is possible to set a single threshold S2 for all mobile phones P, i.e., to detect an object to be charged on a charging surface among a plurality of objects to load, which is not possible with the methods of the previous art.

[0080] Conversely, when no mobile phone P is on the charging surface S, the value of the intensity variation AI is very low.

[0081] This is illustrated in the table below: [Tables 2] Charging device 10 (mA) 11 (mA) 12 (mA) AI (%) No. 1 64 66 62 0.2 No. 2 72.8 66.8 67.6 1.29 No. 3 69.2 64.8 66.4 2.57 No. 4 65.6 62.4 64.4 3.26 No. 5 64.4 69.2 67.6 2.2 No. 6 62.8 61.6 64 0.07 No. 7 61.6 60.8 61.6 1.32 No. 8 59.2 60 61.6 2.56

[0082] The table above illustrates the intensities 10, II, 12 and the variation of intensity AI between the three antennas A0, Al, A2 obtained for a sample of eight chargers No. 1 to No. 8 of the same type in empty, i.e. without mobile phone S placed on the charging surface S. The chargers differ from each other only by the tolerance of the parts from charger to charger.

[0083] According to the said table, it can be observed that the variation in intensity between the three antennas is very low when no mobile phone P is placed on the charging surface S. The variation in intensity is below 4%.

[0084] It can also be noted that for different charging devices of the same type, there is a difference in the variation of intensity at no load (without a mobile phone placed on the charging surface) of a few percentages, about 3%.

[0085] In an improvement of the detection method according to the invention, during preliminary steps EOa and EOb shown in dashed lines in [Fig. 4], the current or representative value of the impedance 10 on the third coil A0 is calculated (step EOa) and compared to a threshold SI (step EOb). If the current 10 is less than this threshold SI, then the detection method is triggered at step EL

[0086] This improvement allows the process to be triggered only if, initially, it is not certain that the user has placed his phone P on the charging surface S, opposite the third coil A0, i.e. in the middle of the charging surface S.

[0087] Indeed, in the case of a large telephone, if it is placed on the charging surface, S, opposite the central coil AO, then the current value 10 is greater than a threshold SI, equal for example to 80 mA. It is known that the presence of the mobile phone can be detected as soon as the current of a coil exceeds this threshold S1.

[0088] However, the problem arises when the intensity 10 is below the threshold SI. In this case, there are two possibilities: either no phone is present on the charging surface S, or a small phone is placed on the charging surface S, opposite the central coil A0. Indeed, small mobile phones do not significantly affect the intensity 10 of the antenna A0. In this case, since the intensity 10 is below the threshold SI, the presence of the mobile phone P is not detected, which is problematic. This is the problem that the invention aims to solve.

[0089] In this case, when the representative value of the impedance 10 is less than the threshold, for example at Sl<80 mA (see table 1), then the detection process is activated (steps El to E4a, E4b).

[0090] The invention therefore makes it possible ingeniously to detect the mobile phone P on the charging surface, by monitoring the variation in intensity between the NFC coils present under the charging surface S.

[0091] Thus, even if the phone has moved or slipped on the charging surface, it will still be detected as present. Furthermore, the detection method according to the invention is energy-efficient and uses the NFC coils already present in the charger for NFC communication with the mobile phone P.

[0092] The NFC antennas therefore have two roles, to ensure NFC communication which is their primary function and according to the invention, to detect the presence of a mobile phone P on the charging surface S.

Claims

Claims

1. Method for detecting an object to be charged (P) on a charging surface (S) of a charging device (D), said device (D) comprising at least three near-field communication antennas (AO, A1, A2), two antennas (A1, A2) each being located at one end (E1, E2) of the device, and a third antenna (AO) being located between the two antennas, the method being characterized in that it comprises: a. determining an intensity (10, II, 12) circulating in each of the antennas, b. calculating an intensity variation (AI) between the three antennas, c. comparing said variation with a predetermined intensity variation threshold value (S2), d. detecting an object to be charged (P) on the surface (S) of the charging device (D) as a function of the result of the comparison.

2. Detection method according to the preceding claim, characterized in that the method is triggered as a function of a result of a comparison between an intensity determination (10) circulating in the third antenna (AO) with a predetermined value (SI).

3. Detection method according to any one of the preceding claims, characterized in that the calculation of a variation in intensity (AI) between the three antennas (AO, Al, A2) is presented in the form: AZ=||^-l|-l^-l|lxl00 H 11 1 112 II With: 10: intensity circulating in the third antenna in mA II: intensity circulating in the first antenna in mA 12: intensity circulating in the second antenna mA

4. Charging device (D) for an object to be charged (P) comprising at least three near-field communication antennas (AO, A1, A2), two antennas each being located at one end (El, E2) of the device (A1, A2), and a third antenna (AO) being located between the two antennas, said device being characterized in that it comprises: has. means for determining an intensity (Ml) circulating in each of the antennas (AO, Al, A2), b. means (M2) for calculating a variation in intensity (AI) between the three antennas, c. means (M3) for comparing said variation with a predetermined intensity variation threshold value (S2), d. means (M4) for detecting an object to be charged (P) on the surface (S) of the charging device (D) as a function of the result of the comparison.

5. Charging device (D) according to the preceding claim, characterized in that it further comprises second comparison means (M5) between an intensity (10) circulating in the third antenna (AO) with a predetermined value (SI).

6. A computer program product comprising program code instructions for executing the steps of the method according to any one of claims 1 to 3 when said program is executed on a computer.

7. Motor vehicle (V) characterized in that it comprises a charging device (D) according to any one of claims 4 to 5.

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