HANDS-FREE ACCESS DEVICE TO A VEHICLE IN THE NEAR FIELD

Abstract

The invention relates to a portable hands-free access device (D) for a motor vehicle (V), said device comprising radio frequency transmission and reception means and a radio frequency antenna (A1), characterized in that the radio frequency antenna is modified by connecting between the two ends of said radio frequency antenna (A1): a) a resonance circuit (C1) at a near-field communication frequency in series with, b) a radio frequency open circuit (C2), c) a near-field communication antenna (A2), electromagnetically coupled to the modified radio frequency antenna (A1), d) near-field communication management means (M1), connected to the near-field communication antenna (A2), e) a rechargeable battery (BAT), f) near-field communication battery recharging means (M2) connected to the near-field communication antenna (A2). Figure for abstract: Fig. 1

Description

Title of the invention: DEVICE FOR HANDS-FREE ACCESS TO A VEHICLE IN THE NEAR FIELD Technical field

[0001] The invention relates to a hands-free access device to a vehicle in so-called near-field communication, for activating a vehicle function, of the “hands-free” access type to a motor vehicle. Prior art

[0002] In a motor vehicle, it is known to use vehicle function activation devices capable of detecting the presence of a hand or a foot of a user of the vehicle and thus enabling the locking or unlocking of all or part of the openings of the vehicle, for example the doors or the trunk. For example, the detection of the presence of a user's hand on or in front of a door handle coupled with the recognition of an identifier of a "hands-free" authentication device worn by this user, enables the locking and unlocking of these openings.

[0003] A so-called "hands-free" access system for a motor vehicle allows an authorized user to lock and / or unlock the openings of his vehicle without having to physically press buttons on a key. To do this, the vehicle identifies a hands-free access device such as portable equipment such as a badge or remote control carried by a key, by the user and if the badge or remote control or the key is located in a predetermined area around the vehicle or in the vehicle and is identified as belonging to the vehicle, then the vehicle automatically locks / unlocks its openings according to the user's intention, without the user having to physically handle a key.

[0004] To do this, when the user approaches the vehicle, communication is established on a wireless communication link between the hands-free access device, for example an electronic badge or a smart mobile phone, and the vehicle function activation device in order to authenticate said authentication device using its identifier.

[0005] For this purpose, the activation device comprises at least one radiofrequency antenna allowing the reception of the identifier sent by the hands-free access device. The activation device is connected to an electronic computer of the vehicle (“ECU”: English abbreviation for “Electronic Control Unit”) to which it transmits the identifier.

[0006] According to the state of the art, the hands-free access device is generally an electronic badge. The signal received by the antenna of the activation device, comprising the identifier of the hands-free access device, is emitted via RF (Radio Frequency) or LF (Low Frequency) waves. The precise location of the hands-free access device around the vehicle is carried out by measuring the intensity of the RF signal received by said device (via the antennas and the electronic control unit) from the vehicle, more commonly called RSSI measurements (Received Signal Strength Indication in English, or measurement of the power received by a signal received by an antenna).The measurement of the power of each signal received by the hands-free access device from each antenna of the plurality of RF (“radio frequency”) or LF (“low frequency”) antennas located on the vehicle V, is received and analyzed by an activation device, on board the vehicle, which thus determines by triangularization, the position of said device relative to said RF antennas, that is to say relative to the vehicle.

[0007] Depending on the location of the hands-free access device identified by the vehicle, in said location zones certain actions specific to said location zones are automatically carried out, unlocking / locking or prior switching on of the passenger compartment lighting (also called “welcome lighting” in English).

[0008] Nowadays, however, these hands-free access methods are susceptible to so-called relay attacks during which a thief will intercept the LF / RF signal exchanged between the vehicle and the hands-free access device in order to deceive the vehicle and unlock it and then start it.

[0009] One solution to this problem is to make the authentication procedure even more secure, for example by using near field communication, or NFC, which requires a proximity of a few centimeters between the hands-free access device and an NFC reader located on the vehicle. This proximity required during the authentication phase makes a relay attack more difficult.

[0010] However, the limited space in a hands-free access badge makes it difficult to integrate an NFC antenna in addition to the electronic circuit and the radio frequency antenna, either the NFC antenna surrounds the electronic circuit and reduces the space allocated to the latter, or the NFC antenna is smaller in size located on one side of the badge, and in this case the NFC communication performance is degraded.

[0011] Another disadvantage of current hands-free access devices is that they operate either on battery for a badge or on a rechargeable battery for a mobile phone. It may happen that the battery is empty or the phone is discharged and therefore authentication is impossible.

[0012] The invention provides a hands-free access device which overcomes the drawbacks of the prior art, i.e. being robust against relay attacks, enabling authentication to be ensured even if the badge battery or the telephone is discharged, ensuring a satisfactory NFC communication range and being easily integrated into a hands-free access device. Statement of the invention

[0013] The invention relates to a portable hands-free access device for a motor vehicle, said device comprising radio frequency transmission and reception means and a radio frequency antenna, characterized in that the radio frequency antenna is modified by connecting between the two ends of said radio frequency antenna: a. a resonant circuit at a near-field communication frequency, in series with, b. an open circuit in radio frequency c. a near-field communication antenna electromagnetically coupled to the modified radio frequency antenna, d. means of managing near-field communication, connected to the near-field communication antenna, e. a rechargeable battery, f. means for recharging the battery in near field communication connected to the near field communication antenna.

[0014] Preferably, the resonance circuit comprises at least one resonance capacitor in near-field communication.

[0015] And the open circuit in radio frequency comprises at least one inductance and at least one capacitance

[0016] Advantageously, the radiofrequency antenna is located at one end of the device.

[0017] The invention also applies to any motor vehicle equipped with a hands-free access device according to any of the characteristics listed above. Brief description of the drawings

[0018] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0019] [Fig.l]: [Fig.l] is a schematic representation of a motor vehicle and a portable hands-free access device according to the invention,

[0020] [Fig.2]: [Fig.2] is a schematic representation of the portable hands-free access device according to the invention,

[0021] [Fig.3]: [Fig.3] is a graph illustrating along a longitudinal axis of the device portable hands-free access to the communication field in near field communication according to the prior art (in solid line) and according to the invention (in dotted line). Description of the embodiments

[0022] In [Fig.l] a motor vehicle V is shown as well as a portable hands-free access device D to said vehicle. The portable device D is equipped with a radiofrequency antenna A1 in order to communicate with said vehicle V. Said device D also comprises a rechargeable battery.

[0023] Access to a motor vehicle V via a hands-free access device is known from the prior art and will not be detailed further here.

[0024] The invention proposes that the portable hands-free access device includes near-field communication means, i.e. “NFC” or Near Field communication in English at 13.56 MHz, which can be easily integrated into the device, requiring little space and making it possible, among other things, to avoid relay attacks but above all making it possible to recharge the battery of the portable device.

[0025] For this purpose, according to the invention, the portable hands-free access device D is modified in such a way that the following are connected between the two ends of said radiofrequency antenna A1: a. a resonant circuit Cl at a near-field communication frequency, in series with b. an open circuit C2 in radio frequency, also called a band-stop circuit, c. a near-field communication antenna A2, electromagnetically coupled to the modified radio frequency antenna Al, d. means of managing Ml communication, in the near field e. a rechargeable BAT battery, f. means of recharging the M2 battery in near field communication.

[0026] Preferably, the resonance circuit Cl comprises at least one resonance capacitor Cres in near-field communication.

[0027] The open radiofrequency circuit C2 comprises at least one inductance Lrf and at least one capacitor CRp connected in parallel.

[0028] The addition of these components to the existing radiofrequency antenna Al modifies the functions of said antenna AL

[0029] This remains a radio frequency communication antenna at radio frequency communication frequencies, but it also allows near field communication at near field communication frequencies.

[0030] The near-field communication antenna A2 included in the device D is electromagnetically coupled to said radiofrequency antenna A1 thus modified.

[0031] The device D then comprises two antennas Al, A2 for near-field communication, a modified antenna Al capable of communicating in the near field, and a near-field communication antenna A2, electromagnetically coupled to the modified antenna Al.

[0032] The advantage of such a device D is the NFC near-field communication range which is extended compared to the prior art, i.e. compared to a portable device equipped only with a near-field communication antenna.

[0033] Preferably, the radiofrequency communication antenna A1 is located at one end (E) of the portable device D.

[0034] Thus the radiofrequency antenna Al modified according to the invention is capable of communicating in the near field with an NFC near field communication reader located on the vehicle V, for example in the door handle P of said vehicle V.

[0035] This is illustrated in [Fig.2].

[0036] The Al antenna thus modified has an extended near-field communication range. This is illustrated in [Fig.3].

[0037] In [Fig.3] the range of the NFC near field communication field in mW is shown along a longitudinal axis (x,-x) along the portable access device D (see [Fig.2]): a. according to the prior art to the SI curve, i.e. with a single near-field communication antenna and b. according to the invention, to the curve S2, that is to say with a radiofrequency antenna Al modified in order to be able to communicate in the near field.

[0038] It is clear that the range of the communication field is extended at the end of the portable device D, where the modified radiofrequency antenna A1 is located (between x=40 and x=15). The field, which does not exist at this location with the device of the prior art, reaches high values ​​(250 mW) with the portable device according to the invention. The ranges of two fields remain approximately identical along the longitudinal axis for values ​​of x less than 15.

[0039] It is evident that this increase in field power allows for easier and more efficient near-field communication between the portable access device and the vehicle's NFC reader.

[0040] The radiofrequency antenna Al thus modified not only allows more robust communication but also allows the rechargeable battery of the device D to be recharged more quickly via the electromagnetic coupling between said modified radiofrequency antenna Al and the NFC antenna A2 itself connected to the rechargeable battery BAT.

[0041] The invention therefore makes it possible to overcome the drawbacks of the prior art in an innovative manner. ingenious, that is to say not only to increase the near-field communication range of the portable access device (D) but also to recharge the device's rechargeable battery via NFC.

Claims

Claims

1. Portable hands-free access device (D) to a motor vehicle (V), said device comprising radio frequency transmission and reception means and a radio frequency antenna (Al), characterized in that the radio frequency antenna is modified by connecting between the two ends of said radio frequency antenna (Al): a. a resonant circuit (Cl) at a near-field communication frequency in series with, b. an open circuit in radio frequency (C2), c. a near-field communication antenna (A2), electromagnetically coupled to the modified radiofrequency antenna (Al), d. means of management (Ml) of near-field communication, connected to the near-field communication antenna (A2), e. a rechargeable battery (BAT), f. means for recharging (M2) the battery in near-field communication connected to the near-field communication antenna (A2).

2. Portable hands-free access device (D) to a motor vehicle (V), according to the preceding claim, characterized in that the resonance circuit (Cl) comprises at least one resonance capacitor (Cres) in near-field communication.

3. Portable hands-free access device (D) to a motor vehicle (V), according to any one of the preceding claims, characterized in that the open radiofrequency circuit (C2) comprises at least one inductance (Lrf) and at least one capacitor (Crf).

4. Portable hands-free access device (D) for a motor vehicle, according to any one of the preceding claims, characterized in that the radiofrequency antenna is located at one end (E) of the device.

5. Motor vehicle (V) characterized in that it is equipped with a hands-free access device (D) according to any one of claims 1 to 4.

Images