Vehicle access key including an electrically conductive shield

Abstract

The invention relates to a key (1) for a vehicle (2), said key (1) comprising: - a housing (10) including an upper shell (100) and a lower shell (101), - a radio frequency signal transmitting / receiving antenna (11), - an electronic support (12) configured to receive said transmitting / receiving antenna (11), characterized in that said key (1) further comprises at least one electrically conductive shield (13) arranged to stabilize the operating frequency of said antenna (11). Figure for abbreviation: Fig. 1

Description

Title of the invention: Vehicle access key comprising an electrically conductive shield

[0001] The present invention relates to a vehicle key. It finds a particular but non-limiting application in access to motor vehicles.

[0002] In the field of motor vehicles, a vehicle key known to those skilled in the art comprises: - a housing comprising an upper shell and a lower shell, - an antenna for transmitting / receiving radiofrequency signals, - an electronic support configured to receive said transmitting / receiving antenna.

[0003] The key is used to open or close the vehicle remotely.

[0004] A disadvantage of this state of the art is that the antenna is sensitive to the physical elements around it and in particular to the fingers or hand of the key holder who uses it. Due to the proximity of these physical elements, the antenna is disturbed. Consequently, the antenna is less efficient. As a result, the access range of the key may decrease. Thus, if conventionally, the key allows remote access from 100 meters, the disturbance could reduce remote access to 50 meters for example.

[0005] In this context, the present invention aims to propose a key which makes it possible to resolve the mentioned drawback.

[0006] To this end, the invention proposes a vehicle key, said key comprising: - a housing comprising an upper shell and a lower shell, - an antenna for transmitting / receiving radiofrequency signals, - an electronic support configured to receive said transmitting / receiving antenna, characterized in that said key further comprises at least one electrically conductive shield arranged so as to stabilize the operating frequency of said antenna.

[0007] Thus, as will be seen in detail later, the shield is arranged so as to stabilize the operating frequency of the antenna and thus reduce the disturbance caused by the hand close to the antenna, whether it be the fingers or the palm of the hand. The operating frequency of the antenna remains the same whether in the presence of the hand or in the absence of the hand.

[0008] According to non-limiting embodiments, the key may further comprise one or more additional characteristics taken alone or according to all the com- technically possible combinations, among the following.

[0009] According to a non-limiting embodiment, said shield is arranged on one of the upper or lower shells or is arranged between one of the upper or lower shells and said electronic support.

[0010] According to a non-limiting embodiment, said shield is a metal shield or a conductive membrane or an electrically conductive paint.

[0011] According to a non-limiting embodiment, said key comprises a shield arranged between said upper shell and said electronic support.

[0012] According to a non-limiting embodiment, said key comprises a shield arranged between said lower shell and said electronic support.

[0013] According to a non-limiting embodiment, said key comprises two shields, one of which is arranged between said upper shell and said electronic support, and the other is arranged between said lower shell and said electronic support.

[0014] According to a non-limiting embodiment, when said at least one shield is arranged on one of the upper or lower shells, it is arranged on an inner face or an outer face of said upper or lower shell.

[0015] According to a non-limiting embodiment, said at least one shield partially or totally covers said electronic support when said at least one shield is integrated into said housing.

[0016] According to a non-limiting embodiment, said radiofrequency signals are transmitted / received according to a high-frequency communication protocol.

[0017] According to a non-limiting embodiment, said high-frequency communication protocol is a BLE™, LTE or UWB communication protocol.

[0018] According to a non-limiting embodiment, said key is an access key to said vehicle or an access and start key to said vehicle.

[0019] According to a non-limiting embodiment, said antenna comprises an antenna trace and at least one reference.

[0020] According to a non-limiting embodiment, the antenna layout is of the meander, Yagi or fractal type.

[0021] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures:

[0022] [Fig. 1] illustrates an exploded diagram of a vehicle key, said key comprising a housing with an upper shell and a lower shell, an antenna, an electronic support and at least one shield, according to a first non-limiting embodiment of the invention,

[0023] [Fig.2] illustrates a top view of the upper shell of the key housing of the [Fig.l], according to a non-limiting embodiment,

[0024] [Fig.3] illustrates a bottom view of the electronic support of the key of [Fig.l] on in which the antenna of the key of [Fig.l] is arranged, according to a non-limiting embodiment,

[0025] [Fig.4] illustrates a bottom view of the electronic support with the antenna of the [Fig.3], said antenna being partially covered by the shield of [Fig.l], according to a non-limiting embodiment,

[0026] [Fig.5] illustrates a bottom view of the electronic support with the antenna of [Fig.3], said antenna being completely covered by the shield of [Fig.l], according to a non-limiting embodiment,

[0027] [Fig.6] illustrates a bottom view of the upper shell of the key housing of [Fig.l] which integrates the electronic support with the antenna covered by the shield of [Fig.4], according to a non-limiting embodiment,

[0028] [Fig.7] illustrates a bottom view of the upper shell of the key housing of the [Fig.l] which integrates the electronic support with the antenna covered by the shield of [Fig.5], according to a non-limiting embodiment,

[0029] [Fig.8] illustrates a schematic profile view of the key of [Fig.l], said key comprising a single shield arranged between the upper shell and the electronic support, according to a first non-limiting variant embodiment,

[0030] [Fig.9] illustrates a schematic side view of the key of [Fig.l], said key comprising a single shield arranged on the side between the lower shell and the electronic support, according to a second non-limiting variant embodiment,

[0031] [Fig.10] illustrates a schematic profile view of the key of [Fig.l], said key comprising two shields, one of which is arranged between the upper shell and the electronic support, and the other is arranged between the lower shell and the electronic support, according to a third non-limiting variant embodiment,

[0032] [Fig. 11] illustrates a non-limiting example of a polar radiation pattern of the antenna of [Fig.l] protected by the shield of [Fig.l],

[0033] [Fig. 12] illustrates a non-limiting example of a polar radiation pattern of the antenna of [Fig.l] without shield,

[0034] [Fig. 13] illustrates a schematic side view of a vehicle key, said key comprising a housing with an upper shell and a lower shell, an antenna, an electronic support and at least one shield arranged on the shell, according to a first limiting variant embodiment of a second non-limiting embodiment of the invention,

[0035] [Fig. 14] illustrates a schematic side view of a vehicle key, said key comprising a housing with an upper shell and a lower shell, an antenna, an electronic support and at least one shield arranged on the lower shell, according to a second non-limiting variant embodiment of a second non-limiting embodiment of the invention.

[0036] Identical elements, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0037] The key 1 for a vehicle according to the invention is described with reference to Figures 1 to 14. In a non-limiting embodiment, the vehicle is a motor vehicle. By motor vehicle is meant any type of motorized vehicle. The motor vehicle is thermal or electric. This embodiment is taken as a non-limiting example in the remainder of the description. In the remainder of the description, the vehicle is thus otherwise called a motor vehicle.

[0038] As illustrated in [Fig.l], the key comprises: - a 10 case, - an antenna 11 for transmitting / receiving radiofrequency signals, - an electronic support 12, - at least one shield 13.

[0039] In a non-limiting embodiment, the key 1 is a key for remote access to the motor vehicle. In a non-limiting embodiment, the key 1 can also be used for starting the motor vehicle. In this case, it is a key for remote access and remote starting of the motor vehicle.

[0040] As illustrated in [Fig.l], the housing 10 comprises an upper shell 100 and a lower shell 101.

[0041] As illustrated in [Fig.2], the upper shell 100 comprises push buttons 100.1 which must be pressed to perform different functions f.

[0042] In the non-limiting example illustrated in [Fig.2], the functions f are: - fl: opening of the motor vehicle 2, - f2: closing of motor vehicle 2, - f3: opening the trunk, - f4: remote start and remote preheating of the passenger compartment of the motor vehicle.

[0043] Thus, in the non-limiting example, the key 1 comprises four push buttons 100.1. On the push buttons 100.1 are affixed associated pictograms 100.2 corresponding to the functions f to be carried out.

[0044] The housing 10 is configured to receive the antenna 11, the electronic support 12 and said at least one shield 13. The upper shell 100 comprises a housing 100.3 (illustrated in FIGS. 6 and 7) to receive the electronic support 12 with the antenna 11. The lower shell 101 is configured to close the housing 10.

[0045] It will be noted that when the holder of the key 1 holds the key 1 in his hand, his thumb is in opposition to his other fingers of the hand to press a push button 100.1. When the holder of the key 1 wants to execute a function f, his thumb will be positioned on the upper shell 100 (as illustrated by the arrow in [Fig.2]) while his other fingers will be positioned on the lower shell 101 of the housing 10. There is a gap between the thumb and the other fingers. The index finger will be located substantially in the middle of the key 1 on the lower shell 101 side. To perform a function f, in a non-limiting example the function fl, the thumb covers a part of the antenna 1 at the location indicated by an arrow P in [Fig.3] for example. It is in particular the thumb which will hinder communication between the antenna 11 (described below) and the motor vehicle in conventional keys. Indeed, the electromagnetic field of an antenna is modified in the presence of any physical element or non-electromagnetically non-neutral material, such as a finger or metal or conductive paint.

[0046] The antenna 11 for transmitting and receiving radiofrequency signals, otherwise called antenna 11, is configured to communicate with the motor vehicle via radiofrequency signals to perform the functions f. For this purpose, the motor vehicle comprises one or more radiofrequency transmitting and receiving modules. In a non-limiting embodiment, said radiofrequency signals are transmitted / received according to a high-frequency communication protocol. It is recalled that the range of values ​​of the high frequencies is between 100 MHz and 10 GHz. In a non-limiting embodiment, the frequency range of the radiofrequency signals is between 2.2 GHz and 8.25 GHz. In a non-limiting embodiment, the communication protocol is the BLE (BlueTooth Low Energy™ in English) or LTE (Long Term Evolution in English) or UWB (Ultra Wide Band in English) communication protocol. It is recalled that the BLE frequency is 2.44GHz, the LTE frequency is 2.2GHz, and the UWB frequency is 8.25GHz. It will be noted that the radio frequency signals can be transmitted according to the same communication protocol as the received radio frequency signals or according to a different communication protocol. In a non-limiting embodiment, the antenna 11 allows remote access to the vehicle between 100 meters and 50 meters. It therefore has an access range (otherwise called operating range) allowing access at this distance. The antenna performances are similar when the antenna 11 is in transmission mode and in reception mode. Therefore, what improves or degrades these performances in transmission acts the same in reception.

[0047] As illustrated in [Fig. 3], the antenna 11 comprises an antenna path 11.11 and at least one reference 11.2 (illustrated in [Fig. 3]). In non-limiting embodiments, the antenna path 11.11 is of the meander, Yagi or fractal type. In the non-limiting example of [Fig. 3], the antenna 11 is of the meander type. In a non-limiting embodiment, the reference 11.2 is a ground reference. In a non-limiting alternative embodiment, the ground reference is that of the electronic support 12. This ground reference being known to those skilled in the art, it is not not described here.

[0048] As illustrated in [Fig.3], the electronic medium 12 is configured to receive the antenna 1. As illustrated in [Fig.l], it is sandwiched between the upper shell 100 and the lower shell 101. In a non-limiting embodiment, the electronic support 12 is a PCBA card for "Printed Circuit Board Assembly" in English. As illustrated in [Fig.3], the electronic support 12 comprises a first part 12.1 which does not carry the antenna 11 and an adjacent second part 12.2 which extends from the first part 12.1 on which the antenna 11 is arranged.

[0049] In a first non-limiting embodiment illustrated in Figures 1 to 10, said at least one shield 13 is arranged between one of the upper 100 or lower 101 shells and said electronic support 12. In a second non-limiting embodiment illustrated in Figures 13 and 14, said at least one shield 13 is arranged on one of the upper 100 or lower 101 shells.

[0050] The shield 13 is electrically conductive. This makes it possible to have a stronger influence on the antenna 11 and its propagation of electromagnetic waves than a hand (finger, palm).

[0051] The shield 13 makes it possible to isolate the antenna 11 from the effect of the hand (fingers and palm) when pressing the push buttons 100.1. The antenna 11 is tuned to a given operating frequency (otherwise called tuning frequency) in the presence of the shield 13.

[0052] Without shield 13, when a hand (finger or palm) approaches the antenna 11, it detunes the antenna 11, namely it changes its operating frequency, and consequently its operating range (radio frequency communication distance) to the vehicle. Furthermore, the hand absorbs part of the energy emitted or received by the antenna 11 when it emits or receives the radio frequency signals S. It is recalled that the radio frequency signals S are electromagnetic waves. Thus, without shield 13, the operating frequency of the antenna 11 varies according to the presence or absence of a hand, and in the presence of the hand loses part of its energy.

[0053] The presence of the shield 13 is arranged so as to allow the operating frequency of the antenna 11 to be stabilized, and to avoid energy loss due to the presence of the hand.

[0054] Indeed, as shield 13 is still present and tuned to antenna 11 in key 1: - the hand which is isolated from the antenna 11 by the shield 13 does not affect the operating frequency of the antenna 11, - the radiofrequency signals emitted or received S by the antenna 11 are channeled by the shield 13 to orient them so as to obtain the radiation pattern of antenna 11 wanted.

[0055] In a non-limiting embodiment, the shield 13 is also part of the ground reference 11.2 of the antenna 11. In another non-limiting embodiment, it is not part of the ground reference 11.2.

[0056] In a first non-limiting embodiment, the shield 13 partially covers the electronic support 12 except at the location where the antenna 11 is located. In a second non-limiting embodiment, the shield 13 completely covers the electronic support 12 including the location where the antenna 11 is located.

[0057] In a first non-limiting embodiment of the shield 13, the shield 13 is arranged between the upper shell 100 and the electronic support 12, or between the lower shell 101 and the electronic support 12. In particular, it is arranged between the inner face of the upper shell 100 and the electronic support 12, or between the inner face of the lower shell 101 and the electronic support 12.

[0058] In a non-limiting embodiment, the shield 13 is fixed to the housing 10 by clipping (not illustrated) of the housing 10. In a non-limiting embodiment, the shield 13 comprises openings 130 illustrated in FIGS. 4 and 5 for arranging the push buttons 100.1.

[0059] In a first non-limiting variant embodiment, the shield 13 is a metal shield made of rigid metal. In non-limiting examples, it may be made of copper alloy, such as CuSn or CuZn, or even stainless steel. In a second non-limiting variant embodiment, the shield 13 is a flexible conductive membrane.

[0060] In a non-limiting embodiment illustrated in [Fig. 4], when the shield 13 is in place in the housing 10, it partially covers the electronic support 12 except at the location where the antenna 11 is located. In this case, the shield 13 comprises a shape substantially equivalent to the first part 12.1 of the electronic support 12 which does not carry the antenna 11. [Fig. 6] illustrates the shield 13 which is placed in the housing 100.3 of the upper shell 100 on the electronic support 12 and which therefore does not cover the antenna 11.

[0061] In a non-limiting embodiment illustrated in [Fig. 5], when the shield 13 is in place in the housing 10, it completely covers the electronic support 12 including the location where the antenna 11 is located. In this case, the shield 13 comprises a shape substantially equivalent to the entire electronic support 12 including the second part 12.2 which carries the antenna 11. [Fig. 7] illustrates the shield 13 which is placed in the housing 100.3 of the upper shell 100 on the electronic support 12 and which therefore completely covers the antenna 11.

[0062] In a first non-limiting variant embodiment illustrated in [Fig.8], the key 1 comprises a shield 13 arranged between the upper shell 100 and the support electronics 12. This allows the antenna 1 to be protected from the thumb of the holder of the key 1 which is located on the side of the upper shell 100 when the holder of the key 1 holds the key 1 and presses a push button 100.1. In this case, the antenna 11 comprises two ground references 11.2, one of which is the shield 13.

[0063] In a second non-limiting variant embodiment illustrated in [Fig.9], the key 1 comprises a shield 13 arranged between the lower shell 100 and the electronic support 12. This allows the antenna 1 to be protected from the other fingers of the holder of the key 1 which are located on the other side of the housing 10, namely on the side of the lower shell 101 when the holder of the key 1 holds the key 1 and presses with the thumb on a push button 100.1. In this case, the antenna 11 comprises two ground references 11.2, one of which is the shield 13.

[0064] In a third non-limiting variant embodiment illustrated in [Fig. 10], the key 1 comprises two shields 13, one of which is arranged between the upper shell 100 and the electronic support 12, and the other is arranged between the lower shell 100 and the electronic support 12. This makes it possible to protect the antenna 11 from the thumb and the other fingers. In this case, the antenna 11 comprises three ground references 11.2, two of which are the two shields 13. This third non-limiting variant embodiment is the combination of the first non-limiting variant embodiment and the second non-limiting variant embodiment.

[0065] In a second non-limiting embodiment of the shield 13, the shield 13 is arranged on one of the upper 100 or lower 101 shells, namely it covers one of the upper 100 or lower 101 shells. In this case, in a non-limiting embodiment, the shield 13 is an electrically conductive paint. In a non-limiting example, the paint is a metallic paint.

[0066] In a first non-limiting variant embodiment (not illustrated), the electrically conductive paint 13 is located on the inner face of the upper shell 100 or on the lower face of the lower shell 101. It will be noted that there may be an electrically conductive paint 13 on the inner face of the upper shell 100 and an electrically conductive paint 13 on the inner face of the lower shell 101. In this case, there are two shields 13. In a second non-limiting variant embodiment, the electrically conductive paint 13 (illustrated in hatching) is located on the outer face of the upper shell 100 ([Fig. 13]) or on the outer face of the lower shell 101 ([Fig. 14]). It will be noted that there may be an electrically conductive paint 13 on the outer face of the upper shell 100 and an electrically conductive paint 13 on the outer face of the lower shell 101.In this case we have two shields 13. .

[0067] The first non-limiting variant embodiment and the second non-limiting variant embodiment can be combined.

[0068] It will be noted that in this second non-limiting embodiment, the push buttons 100.1 are covered by this electrically conductive paint. In a non-limiting example, the electrically conductive paint 13 is a chrome paint which gives an aesthetic appearance to the push buttons 100.1.

[0069] The electrically conductive paint 13 partially or completely covers the upper shell 100 or the lower shell 101.

[0070] It will be noted that if there are several shields 13, the two non-limiting embodiments (shield 13 arranged between one of the upper 100 or lower 101 shells and the electronic support 12, or shield 13 arranged on one of the upper 100 or lower 101 shells) can be combined together and according to all the possible combinations of their different non-limiting embodiment variants.

[0071] [Fig. 11] illustrates the polar radiation pattern of the antenna 11 when it is protected by at least one shield 13. The Y axis represents the effective amount of energy emitted at a given frequency, in the non-limiting example, 2.4 GHz, called in English “return loss”. The lower the “return loss” value, the more energy is emitted. The X axis represents the frequency here 2.4 GHz.

[0072] Compared to the radiation pattern of an antenna without shield protection illustrated in [Fig. 12], it can be seen that the power of the effective energy emitted has changed direction. We go from a direction D of the main lobe of 89 degrees ([Fig. 12]) to a direction D of the main lobe of 17 degrees ([Fig. 11]). The shield 13 has modified the radiation pattern of the antenna 11. Thus, we ensure that the radiation pattern is in accordance with what is expected. Furthermore, in the non-limiting examples illustrated, we go from a lobe of amplitude 1.16 dBi ([Fig.12]) to a lobe of amplitude 1.96 dBi ([Fig.11]). The shield 13 thus makes it possible in this case to amplify the radiation of the antenna 11. It is recalled that a lobe represents the direction of energy concentration in a given direction.

[0073] Of course, the description of the invention is not limited to the embodiments described above and to the field described above. Thus, in another non-limiting embodiment, the communication protocol for transmitting / receiving the radiofrequency signals is a low-frequency protocol, at 10 MHz in a non-limiting example. Thus, in a non-limiting embodiment where there are two shields 13, there could be a combination of partial or total covering of the electronic support 12 by the two shields 13.

[0074] Thus, the invention described presents in particular the following advantages: - it protects the antenna 11 of the thumb and other fingers of the hand as well as the palm of the hand, - it thus allows for an effective antenna 11 whose access range is not modified, - it prevents the antenna 11 from becoming detuned with respect to the operating frequency used, in the non-limiting example 2.44 GHz, for communication with the vehicle, - it helps to avoid energy losses, - it is simple to implement and inexpensive.

Claims

Claims

1. Key (1) for a vehicle, said key (1) comprising: - a housing (10) comprising an upper shell (100) and a lower shell (101), - an antenna (11) for transmitting / receiving radiofrequency signals (S), - an electronic support (12) configured to receive said transmitting / receiving antenna (11), characterized in that said key (1) further comprises at least one electrically conductive shield (13) arranged so as to stabilize the operating frequency of said antenna (11), according to which said at least one shield (13) completely covers said electronic support (12) when said at least one shield (13) is integrated in said housing (10).

2. Key (1) according to claim 1, wherein said shield (13) is arranged on one of the upper (100) or lower (101) shells or is arranged between one of the upper (100) or lower (101) shells and said electronic support (12).

3. A key (1) according to claim 1 or claim 2, wherein said shield (13) is a metal shield or a conductive membrane or an electrically conductive paint.

4. Key (1) according to any one of the preceding claims, according to which said key (1) comprises a shield (13) disposed between said upper shell (100) and said electronic support (12).

5. Key (1) according to any one of the preceding claims, according to which said key (1) comprises a shield (13) disposed between said lower shell (101) and said electronic support (12).

6. Key (1) according to claim 4 and claim 5, according to which said key (1) comprises two shields (13) one of which is arranged between said upper shell (100) and said electronic support (12), and the other is arranged between said lower shell (101) and said electronic support (12).

7. Key (1) according to any one of the preceding claims combined with claim 2, according to which when said at least one shield (13) is arranged on one of the upper (100) or lower (101) shells, it is arranged on an inner face or an outer face of said upper (100) or lower (101) shell.

8. Key (1) according to any one of the preceding claims, wherein said radio frequency signals are transmitted / received according to a high frequency communication protocol.

9. Key (1) according to the preceding claim, according to which said high frequency communication protocol is a BLE™, LTE or UWB communication protocol.

10. Key (1) according to any one of the preceding claims, according to which said key (1) is an access key to said vehicle or an access and start key to said vehicle.

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