EP1407426A1

EP1407426A1 - Method for keyless unlocking of an access door to a closed space

Info

Publication number: EP1407426A1
Application number: EP02754715A
Authority: EP
Inventors: Thierry Roz; Marc Degrauwe
Original assignee: EM Microelectronic Marin SA
Current assignee: EM Microelectronic Marin SA
Priority date: 2001-07-05
Filing date: 2002-06-20
Publication date: 2004-04-14
Also published as: WO2003005309A1; US6882268B2; US20040178882A1

Abstract

The invention relates to a method for keyless unlocking of an access door to a closed space, in particular a motor vehicle, which is carried out by means of an electronic system, comprising a control module for an electronic lock, associated with the said door and a portable transponder for authorised users. The method comprises sending an interrogation signal at low frequency from the control module to the transponders and also the exchange of data at high frequency. The control module has reception means for the above which are at least continuously in a listening mode. Said method is characterised in that the low frequency transmitters are inactive in a preliminary functional mode, the high frequency transmission means in the transponder periodically emits an activation signal for said transmission means in order that the above are only activated during limited periods, which ensures the reception of an interrogation signal for a transponder entering the low frequency communication region.

Description

METHOD OF UNLOCKING THE "KEYLESS" ILLUMINATION OF A DOOR OF ACCESS TO A CLOSED SPACE

The present invention relates to a "keyless" unlocking method for an access door to an enclosed space, in particular a car. A person skilled in the art knows several modes of implementation and variants of such methods for opening the door of a car, that is to say unlocking his electronic lock, or allowing it to start. , in which the ignition keys or traditional mechanical keys are replaced by transponders or RFID electronic units. Thus, the activation of the electronic lock is controlled via wireless communication between a control device associated with the door and at least one transponder intended for this application and arranged to communicate in particular an identification code.

Document US 4,688,036 discloses a "keyless" access system for a motor vehicle, in which provision is made to activate the device for controlling the electronic lock, in particular the signal transmission and reception circuits. electromagnetic, only after activation of a manual switch by the user. The user in possession of an authorized transponder, therefore actuates a switch arranged outside the car to first activate the transmitter of the control device so that the latter can send an interrogation signal to the transponder after the to have woken up. Thus, the activation of the electronic transmission and reception circuits of the system and the communication protocol making it possible to determine whether the transponder is authorized take place between the actuation of the external switch and the sending of an unlocking signal. to the electronic lock.

By providing an external manual switch in the process of opening a door using a transponder, the power consumption of the door lock control device is limited, this control device being activated only during a given period of time following the actuation of the external switch.

It will indeed be noted that the continuous activation of the control device, in particular the periodic sending of an interrogation signal to detect the presence of an authorized transponder, generates a high consumption of energy, in particular because of certain materials forming the car. Although the source of energy in a car can be important, in particular by taking the energy from a battery of this one, the continuous activation of the means of emission of electromagnetic signals can lead to the discharge of the battery in question when the vehicle is not used regularly. Document US Pat. No. 4,688,036 plans to use a single communication frequency and to arrange the external switch under the handle of the door in question.

Document DE 198 27 586 describes a more sophisticated car access system, in which low frequency (LF) and high frequency (HF) communication is provided so as to increase the speed of transmission of the coded data between the electronic device for unlocking a door and an authorized transponder, the presence of which has been validly detected, opens the door. The speed of this communication is particularly important in the context of the main embodiment proposed where the circuit for transmitting an interrogation signal is activated by the actuation of the handle used to open the door. It is therefore preferable in such an embodiment that the unlocking of the electronic lock is rapid, without which the user initially has a locked lock when he pulls on the handle to open the door. It will be noted that the low frequency transmitter is mainly used to send the interrogation signals to the transponders in a small area, close to the door.

As shown in FIG. 1 appended, the region for receiving a LF interrogation signal by a transponder defines approximately a semicircle 2 having a radius of 1.5 to 2 m around the antenna 6 arranged in a door of the car 8. On the other hand, the circle 4 of high frequency communication between the transponder 10 and the HF receiver arranged in the car typically has a radius of at least 30 m.

Document DE 198 27 586 also provides for arranging in the transponder a remote actuation button for the electronic lock. Thus, when the user wishes to open one or more doors of his car remotely, it suffices for the latter to press the switch button of the transponder so that the latter sends an HF signal to the HF reception means of the device for controlling the locks. This improved embodiment requires that the HF receiver means of the control device be in permanent or almost permanent listening. Although this function requires a certain amount of energy, the consumption generated is however relatively low for conventional energy sources which can be fitted in cars.

Document DE 198 27 586 also proposes a particular embodiment in which there is no provision for an external switch for activating the communication means of the device for controlling the lock, the low-frequency transmission means continuously sending, cyclically, a signal question. Since the communication radius is typically 1.5 to 2 m for the LF transmitter, the authorization protocol for opening a door can be started as soon as a transponder enters the LF communication region. When a user equipped with a transponder actuates an external switch of the vehicle, this transponder is located between 0.5 and 1 m from the LF transmitter. In the case of this particular embodiment, on the assumption that the user is walking approximately at the speed of 1 m / s, the protocol for authorizing the opening of the door can begin approximately one second before the time where the user reaches the door handle. Thus, the communication time available is greatly increased so that it is possible to implement a highly secure identification protocol and to be able to unlock the electronic lock before the user pulls on the handle to open the door . This feature increases the comfort of using the "keyless" opening system. However, currently, this embodiment is not used in practice because it generates a large consumption of energy, as has been explained above. Given this major problem, car manufacturers generally plan to open the doors of a car either by actuating the handle or by pressing a button-switch arranged on the surface of the transponder.

The object of the present invention is to alleviate the aforementioned problem while retaining the optimum use of the low frequency communication region of the control device.

To this end, the invention relates to a method for unlocking an access door to an enclosed space, the characteristics of which are given in claim 1 attached. Thanks to the characteristics of the method according to the invention, it is possible to activate the low frequency transmission means of the control device of an electronic lock before the transponder enters the communication region of these transmission means; without having to manually activate a switch on the transponder. Indeed, the periodic sending of an activation signal from the LF transmission means of the control device makes it possible to keep your hands free during the preliminary operating mode of the electronic system. This preliminary mode can be continuously operated as long as the transponder is powered.

The periodic sending of an activation signal of the LF emission means does not generate any additional consumption for the vehicle when it is planned to be able to activate this control device remotely using a high signal frequency sent by the transponder. Indeed, in such a case currently conventional, the control device has its HF reception means continuously activated. In addition, the transponders are already equipped with HF transmission means. Concerning the consumption of a transponder, an average consumption to supply the LF reception system in a listening mode consumes approximately 2 to 5 μA. If it is planned to send the activation signal of the LF transmission means with a repetition period of approximately 30 seconds, the additional average consumption for the transponder can be estimated at approximately 3 μA. This additional consumption is certainly significant but remains low enough to allow the functionality specific to the present invention to be integrated into a door opening system meeting the required autonomy criterion; even when the preliminary operating mode of the electronic system remains permanently activated at least outside the periods of activation of the low-frequency transmission means of the electronic lock control device. The present invention will be described in more detail below with the aid of the following description of embodiments of the method of the invention, given by way of non-limiting examples, made with reference to the attached drawing in which :

- Figure 1, already described, schematically shows a system for unlocking a door of a car in which it is intended to communicate at low frequency and also at high frequency;

- Figures 2 and 3 respectively show a control device for an electronic lock and a transponder associated therewith, which are used for the implementation of the present invention; and

- Figure 4 is a diagram schematically representing various stages of an embodiment of the method according to the invention.

Using FIGS. 2 and 3, an embodiment of an electronic system for implementing the method according to the invention will be briefly described below.

This electronic system comprises on the one hand a device 12 for controlling at least one electronic lock 14 of an access door to an enclosed space, in particular a car, and on the other hand at least one transponder 16 intended for be worn by a person authorized to enter said enclosed space, in particular to enter said car.

The device 12 is formed in particular of a central data management unit 20 associated with a high frequency (HF) receiver circuit 22 connected to an antenna 23 and to a low frequency (LF) transmitter circuit 24 connected to an antenna 25 The circuits 20, 22 and 24 are supplied by a battery 26 via a management circuit 28 of food. The central unit 20 is connected to a circuit 30 for controlling at least one electronic lock, the latter circuit being itself electrically connected to the electronic lock (s) of the door (s) access to the confined space. In an alternative embodiment for a particular embodiment, there is provided a high frequency transmitter circuit 32 connected to the antenna 23 or to another similar antenna.

The transponder 16 also includes a data management unit 36 associated with a BF receiver circuit 38 connected to an antenna 39 and an HF transmitter circuit 40 connected to an antenna 41. The circuits 36, 38 and 40 are powered by a battery 44 via a power management circuit 46. In a particular embodiment, the transponder 16 also includes an HF receiver circuit 48. The transmitting or receiving units of the transponder are arranged so as to be able to communicate with the corresponding units of the device 12. In a particular embodiment, provision is made to arrange a switch 50 actuable by a button arranged on the surface of the transponder. This switch makes it possible to remotely actuate an electronic device of a car associated with the device 12, in particular an electronic lock.

The method according to the invention provides that at least part of the communication protocol between the transponder and the electronic lock control device uses at least one low frequency signal, that is to say requires low communication frequency and therefore at close distance between the transponder 16 and the device 12. In particular, it is intended that the device 12 sends a LF interrogation signal to the transponder and receives in response an identification signal. This identification signal can contain various messages and must be understood in a broad sense. The protocol for identifying and triggering the unlocking of the electronic lock may provide for a combination of information transmitted at low frequency and also at high frequency. In the embodiment given in FIGS. 2 and 3, it is provided that only the device 12 sends LF signals. It will be noted here that HF includes electromagnetic signals having a high frequency, that is to say a frequency included in the HF band or in a higher frequency band, in particular UHF.

According to the invention, it is provided that, in a preliminary operating mode, the LF transmission means 24, 25 are inactive and that the HF transmission means 40, 41 of the transponder (s) 16 of the system transmit periodically an HF signal to activate the LF transmission means of the device 12. By "inactive" or "deactivated", it should be understood that the transmission means are in a low consumption mode in which no signal emission occurs. As regards the reception means, it is understood that they are at rest and not in a listening mode.

Assuming that the HF communication distance from the system is around 30 m, we can, in a first variant, provide for a repetition period of the activation signal a little more than 5 seconds. Thus, a user approaching the car running at a speed of approximately 5 m / sec will send at least one activation signal capable of being received by the device 12 before this user reaches the handle of the door to be opened. . In another variant, in order to save the electrical energy consumed by the transponders, the repetition period is provided between 10 seconds and 1 minute, in particular 30 seconds. This latter value activates the LF emission means for a user approaching the car while walking at a speed of around 1 m / s.

According to a preferred embodiment, the LF transmission means of the device 12 are deactivated after a certain determined activation period if no valid identification signal has been received by the device. In this case, said preliminary mode is then selected again.

Thanks to the characteristics of the invention, it is possible to have a "keyless" unlocking process for an access door to a car which is effective without consuming too much energy and discharging the battery. Indeed, preferably, the LF interrogation signal is sent with a high repetition rate as soon as the LF transmission means of the device 12 have been activated. Thus, as soon as a transponder enters the communication region BF associated with these transmission means 24, 25, the identification and authorization protocol for actuating the electronic lock is implemented. Typically, the time available between the reception of an interrogation signal by the transponder 16 and the actuation of the handle to open the door considered is here at least one second. The time available to the unlocking protocol of the electronic lock and therefore approximately at least three times greater in the case where the LF transmitter means are activated by the start of the actuation of the handle of said door.

We therefore distinguish, in the case of the method described here, a preliminary operating mode and a detection mode, the latter mode being provided as soon as said LF transmitter means are activated for the cyclic sending of an interrogation signal and at less until receipt of a said identification signal or, in the absence of such reception, until the end of said determined activation period.

According to a particular variant of the method according to the invention, it is provided that, when an interrogation signal is received by the reception means LF of the transponder 16, this transponder ceases to send said activation signal as long as it receives low frequency signals from the device 12 at least periodically.

In Figure 4 is shown a diagram of an embodiment of the method according to the invention. When the door (s) of a vehicle are closed and no authorized transponder maintains communication or any other type of interaction with the control device 12, the system and in particular the device 12 are switched on. in a low consumption operating mode. However, the HF receiving means of the device 12 are in a listening mode. As long as no UHF message is received, the system remains in this operating mode. On the other hand, if a UHF message is received, the latter is decoded and the destination of the message is determined. In the context of the process considered, this may be a command to open the door remotely by means of the manual switch 50 (FIG. 3), or a command to activate the LF transmitter of the device 12, or else of another message foreign to the process considered. In the latter case, the system remains in or returns to low consumption mode. In the other two cases, the validity of the command is tested and, in the positive case, the corresponding action is carried out, ie either unlocking the electronic lock also simply called "door opening", or the activation of said LF transmitter causing the sending of an interrogation signal cyclically.

Obviously, a person skilled in the art can design various implementation variants here. In a first variant, it is provided that the HF signals transmitted by the transponders have a header part for the commands so as to indicate whether it is a said identification signal or a said activation signal. In this case, only the message header should be read or decoded first and the next part of the message should only be decoded if the header corresponds to a command provided by the system. In another variant in which the UHF messages received are decoded directly, provision is preferably made to test first whether it is a valid command to activate said LF transmitter since an opening command by actuating d a switch 50 is generally carried out at a certain distance from the car. Said activation signal may contain an identification sequence which limits the transponders capable of activating the vehicle's LF transmitter. Preferably, it is provided that only the transponders authorized for a given vehicle and identified as such can activate this LF transmitter. In another variant, it can be provided that, when the LF transmitter is activated, the system ignores other activation control signals and checks only if it is an authorized opening control signal.

It will be noted that it is possible to provide, in the context of the method according to the invention, that the activation of the LF emitting means of the device 12 is also carried out by the actuation of the handle of the door considered or of another external switch. meant for that purpose. This can make it possible to increase the robustness of the system and in particular to remedy a situation where the transponder has not supplied a valid activation command signal or in which this signal has not been received for any reason.

According to a particular implementation, when said activation signal is received by the device 12, the latter sends a receipt signal to the transponder using the transmitter circuit 32 (FIG. 2) to the transponder 16 in which is arranged an HF 48 receiver circuit. This receipt signal is used to signal to the transponder having supplied the activation signal that it has been detected. According to a preferred variant, said transponder activates, following reception of the receipt signal, the receiver means LF in a flow mode so as to be able to receive an interrogation signal. On the other hand, the BF 38 receiver is deactivated at least most of the time when the system is operating in said preliminary mode. This last characteristic is particularly advantageous by the fact that it makes it possible to reduce the energy consumption of the transponders since they activate the LF listening means only during limited periods.

According to another embodiment of the method of the invention, it is provided that said identification signal and said activation signal are respectively transmitted at first and second different frequencies in the UHF band. To this end, the HF reception means 22, 23 are arranged with first and second listening channels corresponding respectively to the first and second frequencies. Likewise, the HF transmission means 40, 41 of the transponder 16 are arranged to be able to transmit in one or the other of these frequencies. Thanks to this characteristic, it is thus possible to differentiate the type of command as a function of the frequency of the signal received by the device 12. This eliminates the need to determine the type of command received and in particular to provide an head determining this type.

In a preferred variant of this latter embodiment, only the first channel is selected during the periods of activation of the LF transmission means of the device 12. Thus, when these means are activated, the device 12 no longer receives signals d activation of its LF transmission means.

Claims

1. Method for unlocking "without a key" an access door to an enclosed space, in particular a car, by means of an electronic system comprising on the one hand a control device (12) for a lock electronics (14) of said door equipped with a first electronic data management unit (20) associated with first means for transmitting (24, 25) low frequency signals and with first receiving means (22, 23 ) of high frequency signals, and on the other hand at least one portable transponder (16) comprising a second electronic data management unit (36) associated with second means of reception (38, 39) of said low frequency signals and to second transmission means (40, 41) of said high frequency signals, this method providing for the sending of an interrogation signal to said at least one transponder by said first transmission means and, in response, the sending of an identification signal by said at least a transponder for controlling said electronic lock, said first transmission means of said control device being activated by a signal sent by said second transmission means of said at least one transponder, characterized in that it is provided, in a preliminary mode of operation of said system where said first transmission means are inactive, that said second transmission means periodically transmit a high frequency signal for activation of these first transmission means.

2. Method according to claim 1, characterized in that said activation signal is sent with a repetition period greater than 5 seconds.

3. Method according to claim 2, characterized in that said repetition period is substantially between 10 seconds and 1 minute.

4. Method according to one of the preceding claims, characterized in that said first transmission means are deactivated after a determined activation period if no valid identification signal has been received, said preliminary mode then being again selected by said electronic system.

5. Method according to one of the preceding claims, characterized in that, when an interrogation signal is received by said second reception means, said transponder ceases to send said activation signal as long as it receives signals at low frequency of said control device at least periodically. _t

6. Method according to one of the preceding claims, characterized in that, when said activation signal is received by said first reception means, a receipt signal is sent at high frequency using third transmission means (32) of said control device, to signal to said transponder having supplied this activation signal that it has been detected, this transponder comprising for this purpose third reception means (48).

7. Method according to claim 6, characterized in that, after reception of a receipt signal, said transponder then activates said second reception means in a listening mode, these second means being deactivated at least most of the time during said preliminary mode of said electronic system.

8. Method according to one of the preceding claims, characterized in that said second transmission means send control signals whose header part indicates whether it is said identification signal or said signal d activation.

9. Method according to one of claims 1 to 7, characterized in that said identification signal and said activation signal are respectively transmitted at first and second different high frequencies, said first receiving means having first and second listening channels corresponding respectively to these first and second frequencies.

10. Method according to claim 9, characterized in that only said first channel is selected during the periods when said first transmission means are activated.