Identification transmitter with reduced power consumption

Abstract

Identification transmitter (1) of a locking system of a vehicle, designed to identify an authorized person to unlock and / or start the vehicle, with - a receiving unit (10) designed to receive a transmission signal that can be transmitted by a transmission-reception module in the vehicle, - a microcontroller (11) for controlling the receiving unit (10), and with - an energy storage device (12) for supplying energy to at least the receiving unit (10) and the microcontroller (11), - a motion sensor (13) designed to sense a movement of the identification transmitter (1), wherein - at least the receiving unit (10) can be switched off by the microcontroller (11), - if the motion sensor (13) senses a lack of movement of the identification transmitter (1) for a minimum period of time, characterized in that the microcontroller (11) is designed to diagnose the motion sensor (13) in such a way that a defect in the motion sensor (13) can be diagnosed by means of the microcontroller (11), wherein the identification transmitter (1) has a manually operable switching means (16), wherein the diagnosis is carried out in such a way that if the switching means (16) is manually operated and the sensing of a movement of the identification transmitter (1) by the motion sensor (13) fails to occur, a defect in the motion sensor (13) is diagnosed.

Description

[0001] The present invention relates to an identification transmitter of a vehicle locking system, designed to identify an authorized person to unlock and / or start the vehicle. The identification transmitter comprises a receiving unit designed to receive a transmission signal that can be emitted by a transceiver module in the vehicle. A microcontroller is provided for controlling the receiving unit. The identification transmitter further comprises an energy storage device for supplying energy to at least the receiving unit and the microcontroller. Furthermore, a motion sensor is provided in the identification transmitter, which is designed to sense a movement of the identification transmitter, according to the preamble of claim 1. STATE OF THE ART

[0002] DE 199 27 253 C2 discloses an identification transmitter for a vehicle locking system that has a motion sensor for detecting movement of the identification transmitter. If the identification transmitter is not moved for a specified period of time, communication with the transceiver module in the vehicle is disabled. This ensures that an authorization check for unlocking the vehicle's locking system and / or starting the vehicle can only take place if the identification transmitter has been moved within a specific time interval before the authorization check. The transmission of an identity code can only be authorized if this criterion is met.Thus, when verifying whether a person is permitted to unlock and / or start the vehicle, an additional criterion is whether the identification transmitter has been moved within a time interval of, for example, 10 to 30 seconds prior to the authorization check. This takes advantage of the fact that an authorized person must generally have approached the vehicle or sat in the vehicle seat immediately before the authorization check, meaning that the identification transmitter worn by the user was exposed to movement, acceleration, or vibration.This can counteract so-called relay station attacks, in which technical means are used to simulate the presence of the identification transmitter in the vicinity of the vehicle, allowing an unauthorized person to unlock or even start the vehicle without the knowledge of the authorized person. If such an unauthorized remote query is attempted, there is a high probability that the identification transmitter was not moved immediately before the authorization request, for example, if it was left in the authorized person's living space.

[0003] Such mobile identification transmitters have a power supply in the form of a battery, preferably a button cell. In order for the identification transmitter to transmit an authentication signal to the transceiver module in the vehicle, the identification transmitter must first receive an LF signal (e.g., 125 kHz) transmitted by the transceiver module in the vehicle. The field strength with which the transceiver module transmits the LF signal is designed to be so weak that the identification transmitter can only receive it in the immediate vicinity of the vehicle. Once the LF signal is received by the receiver unit in the identification transmitter, the signal is analyzed by the microcontroller, and an HF module in the identification transmitter sends the authentication signal back from the identification transmitter to the transceiver module in the vehicle.Only upon receipt of the authentication signal from the identification transmitter is proof of a person's authorization to unlock and / or start the vehicle provided.

[0004] To ensure continuous reception of the identification transmitter, especially the receiver unit in the identification transmitter, a quiescent current is required, which the energy storage unit uses to feed the receiver unit and / or the microcontroller. This quiescent current flows continuously, so the service life of the energy storage unit, for example, the button cell in the identification transmitter, is limited.

[0005] Vehicle manufacturers often require service lives for the energy storage devices in the identification transmitter that cannot be achieved due to the required supply of a quiescent current.

[0006] Furthermore, DE 10 2009 011 471 A1 discloses a device for synchronizing multiple transceivers in a vehicle's communication system. DE 697 14 470 T2 describes a key fob device connected to a diagnostic collection device.

[0007] It is therefore the object of the present invention to provide an identification transmitter of a locking system of a vehicle which overcomes the disadvantages of the above-mentioned prior art, and in particular it is the object of the present invention to provide an identification transmitter with a reduced power consumption.

[0008] This object is achieved on the basis of an identification transmitter for a vehicle according to the preamble of claim 1 in conjunction with the characterizing features.

[0009] The invention includes the technical teaching that at least the receiving unit can be switched off by the microcontroller if the motion sensor senses a lack of movement of the identification transmitter for a minimum period of time.

[0010] The invention is based on the idea of at least reducing the power consumption from the energy storage device by having the microcontroller switch off the receiving unit. If the identification transmitter has not been moved for an extended period, it can be assumed that it has been put away, thus eliminating the need for the authorized person to unlock and / or start the vehicle without first moving the identification transmitter at least briefly. Power consumption can be reduced to such an extent that only the motion sensor remains activated. The majority of the energy consumption in the idle state of the identification transmitter is generated by the receiving unit, and if this is switched off, a large part of the energy consumption is eliminated.During vehicle operation, a significant portion of the vehicle's service life is spent in idle mode, during which the vehicle is parked and the identification transmitter is also not in use. This non-use is sensed by the motion sensor, and thus the power supply to the receiving unit is only resumed when the microcontroller, in conjunction with the motion sensor, senses use of the identification transmitter. The identification transmitter can, for example, be integrated into the vehicle key. The inventive deactivation of the receiving unit by the microcontroller when the motion sensor detects immobility of the identification transmitter for a minimum period of time has the advantage of significantly extending the service life of the energy storage device.The energy storage unit, often designed as a battery, especially a button cell, can supply the identification transmitter with power for up to 5 years or longer, thus significantly extending the service life of the energy storage unit compared to identification transmitters in which the receiving unit is permanently on standby.

[0011] Advantageously, the deactivation of the receiving unit can at least comprise a deactivation of the receiving unit, in particular such that the deactivation leads to a reduction in the current consumption of the identification transmitter to a maximum of 2 µA, in particular to a maximum of 0.4 µA. By deactivating the receiving unit, the solution according to the invention simultaneously achieves the advantage that relay station attacks are no longer possible, so that the motion sensor in the identification transmitter leads both to the advantage of reducing the power consumption in the identification transmitter and to the advantage of being able to ward off relay station attacks, since the receiving unit does not respond to an LF signal from the transceiver module in the vehicle when the identification transmitter is put down and has not been moved for a minimum period of time.This means that the identification transmitter does not respond to the LF signal, which is sent to the identification transmitter, for example, by a relay station module. If the current consumption is only 0.4 µA, this can describe a state of the identification transmitter that only supplies power to the motion sensor as a means of monitoring movement of the identification transmitter. If the current consumption of the identification transmitter is still 6 µA with an activated receiver unit, a maximum current consumption of 0.4 µA can reduce the current consumption by a factor of 15.

[0012] With further advantage, the identification transmitter can comprise an RF module for communication with the transceiver module in the vehicle, wherein the communication includes a query as to whether the identification transmitter is located inside or outside the vehicle. The vehicle can be equipped with LF antennas that can communicate with the receiver unit of the identification transmitter. This allows the information to be transmitted to the identification transmitter as to whether it is located inside or outside the vehicle.

[0013] If the identification transmitter is located in the vehicle, the minimum time for the microcontroller to deactivate the receiving unit can be at least 30 minutes, preferably at least 1 hour, and particularly preferably at least 2 hours. If the identification transmitter is located outside the vehicle, the minimum time for the microcontroller to deactivate the receiving unit can be at most 10 minutes, preferably at most 5 minutes, and particularly preferably at most 2 minutes. The identification transmitter can be placed in the vehicle, for example in the jacket of the authorized person. If the authorized person wants to start the vehicle, for example by pressing the start button to start the engine, communication takes place between the identification transmitter located in the vehicle and the transceiver module in the vehicle.It can be assumed that the vehicle is already unlocked and has been unlocked for an extended period of time, for example, up to two hours. If the authorized person then presses the start button to start the vehicle's engine, the ID transmitter can be queried by the vehicle's transceiver module even after an extended period of time. If the minimum time for the ID transmitter to be in the vehicle has been exceeded, the authorized person can be prompted via a display in the vehicle to move the ID transmitter so that the motion sensor in conjunction with the microcontroller reactivates the receiver unit in the ID transmitter.

[0014] If the ID transmitter is outside the vehicle, it can be assumed that the ID transmitter has been discarded if the motion sensor no longer detects any movement for a minimum period of time. To increase security against a relay station attack and to better reduce the power consumption of the ID transmitter, the minimum period can be reduced to, for example, two minutes if the ID transmitter is outside the vehicle.

[0015] In particular, the information as to whether the identification transmitter is located inside or outside the vehicle can be stored in the identification transmitter. Furthermore, each time a vehicle's door is opened or closed, the information as to whether the transmitter is located inside or outside the vehicle can be transmitted to the identification transmitter.

[0016] Another advantage is that the receiving unit can be configured to periodically check for receipt of the transmission signal from the transceiver module in the vehicle. This process, also known as "polling," further reduces the power consumption of the identification transmitter. If the identification transmitter in the vehicle has not been moved for an extended period, the display can prompt the user to move the key once.

[0017] According to the present invention, the microcontroller of the identification transmitter is designed to diagnose the motion sensor in such a way that a defect in the motion sensor can be diagnosed using the microcontroller. The diagnosis is performed in such a way that when a switching device on the identification transmitter is manually operated by an authorized person, the motion sensor must also detect movement of the identification transmitter. If the movement of the identification transmitter is not detected during manual operation of the switching device, a defect in the motion sensor can be assumed. If the motion sensor is defective, the receiving unit can be kept in permanent standby. For example, an information signal can be sent to the transceiver module in the vehicle so that the defect in the motion sensor can be read out by a specialist workshop via a corresponding interface in the vehicle.

[0018] Advantageously, the microcontroller can be designed such that it can be brought into an intermediate state in which the supply current of the microcontroller through the energy storage device is less than 1 µA, in particular less than 0.4 µA. In this switching state, the motion sensor and the manually operable switching means on the identification transmitter can be active, wherein the receiving unit and a timer present in the microcontroller and the microcontroller itself are switched off. In this state, the current consumption from the energy storage device can be, for example, 0.4 µA. The microcontroller can in particular be brought into a further intermediate state in which the motion sensor, the manually operable switching means and a timer present in the microcontroller are switched on, and the receiving unit and the microcontroller themselves are switched off.In this intermediate state, the supply current provided by the energy storage device can be, for example, 2µA.

[0019] The object of the present invention is further achieved by a method for operating a locking system for a vehicle with an identification transmitter for identifying an authorized person to unlock and / or start the vehicle, with a receiving unit for receiving a transmission signal from a transmission-receiver module in the vehicle, a microcontroller for controlling the receiving unit, an energy storage device for supplying energy to at least the receiving unit and the microcontroller, and a motion sensor by which a movement of the identification transmitter is sensed. The method at least provides that a period of time is determined by the microcontroller in conjunction with the motion sensor as to whether the identification transmitter is immobile over the period of time. Furthermore, a comparison of the period of immobility with a minimum period of time is carried out, and a shutdown of the receiving unit by the microcontroller is then provided.if the motion sensor detects that the identification transmitter is motionless when the minimum time period is reached.

[0020] According to an advantageous development of the method, the identification transmitter can query, by means of communication with the transceiver module in the vehicle, whether the identification transmitter is located inside or outside the vehicle. If the identification transmitter is located inside the vehicle, the minimum time for the microcontroller to deactivate the receiving unit can be at least 30 minutes, preferably at least 1 hour, and particularly preferably at least 2 hours. If the identification transmitter is located outside the vehicle, the minimum time for the microcontroller to deactivate the receiving unit can be at most 10 minutes, preferably at most 5 minutes, and particularly preferably at most 2 minutes.

[0021] With further advantage, the vehicle can have a display means by which the authorized person can be requested to move the identification transmitter, in particular if the identification transmitter is in the vehicle and has not been moved for the minimum period of time and in particular if the authorized person signals the intention to start the vehicle. PREFERRED EMBODIMENT FOR IMPLEMENTING THE INVENTION

[0022] Further measures improving the invention are described in more detail below, together with the description of a preferred embodiment of the invention, with reference to the figures. They show: Fig. 1 a schematic view of an identification transmitter with the features of the present invention and Fig. 2 a flowchart for the operation of an identification transmitter according to the present invention.

[0023] Fig. 1 shows an identification transmitter 1 of a locking system of a vehicle, and the identification transmitter 1 can be designed, for example, in the form of a check card, or the identification transmitter 1 is integrated in the key of the vehicle.

[0024] The identification transmitter 1 is a component of a locking system of the vehicle and is designed to identify an authorized person who is authorized to unlock and / or start the vehicle.

[0025] The identification transmitter 1 has a receiving unit 10 designed to receive a transmission signal that can be emitted by a transmission / reception module in the vehicle. The receiving unit 10 can comprise receiving coils 17; in particular, three receiving coils 17 can be provided in an orthogonal arrangement in the identification transmitter 1. This allows the transmission signal to be received by the transmission / reception module regardless of the spatial position of the receiving unit 10. The transmission signal is designed, in particular, as an LF signal and forms an H-field with an alternating frequency of, for example, 125 kHz. This can induce a current in at least one receiving coil 17, which can be sensed by the microprocessor 11. The receiving unit 10 is thus formed by a component of the microcontroller 11 together with the receiving coils 17.

[0026] The identification transmitter 1 is further equipped with an energy storage unit 12, which serves to supply energy to at least the receiving unit 10 and the microcontroller 11, but in particular also to supply energy to the motion sensor 13. Furthermore, the identification transmitter 1 contains an RF module 14, which can send an identification signal back to the transceiver module in the vehicle via an antenna 15, for example, to authenticate the authorized person in possession of the identification transmitter 1.

[0027] The motion sensor 13 is shown in connection with the microcontroller 11, which according to the invention can be switched off when the motion sensor 13 senses a lack of movement of the identification transmitter 1 for a minimum period of time.

[0028] By switching off the receiving unit 10, a longer service life of the energy storage device 12 can be achieved, which supplies power to both the microcontroller 11 with the receiving unit 10 and the RF module 14. The quiescent current drawn by the microcontroller 11 and the receiving unit 10 from the energy storage device 12 can be approximately 6 µA when the receiving unit 10 is switched on. If the microcontroller 11 switches off the receiving unit 10 when the motion sensor 13 no longer detects any movement of the identification transmitter 1 for a minimum period of time, the quiescent current can be reduced to 0.4 µA when the receiving unit 10 is switched off.

[0029] Only when the motion sensor 13 detects movement of the identification transmitter 1 again, for example, when the authorized person picks up the identification transmitter 1 and / or when a switching device 16 present on the identification transmitter 1 is manually operated by the authorized person, can the receiving unit 10 be reactivated by the microcontroller 11. The switching devices 16 are designed, for example, as buttons, which can be used to unlock or lock the vehicle, or, for example, to open or close a specific flap on the vehicle. If the microcontroller 11 detects actuation of at least one switching device 16, the receiving unit 10 can then be returned to the activated state.

[0030] Fig. 2 shows a flow chart of a method for operating the locking system for the vehicle with an identification transmitter 1 of the Fig.1. In switching state A, the receiving unit 10 and the switching means 16 can be activated. Furthermore, a timer can be present in the microcontroller 11, which serves to determine the time until the minimum time is reached and which can also be activated.

[0031] If query X determines that the minimum time period has been reached, after which neither a transmission signal has been received by the receiving unit 10 nor a switching device 16 has been activated, the state of the identification transmitter 1 can be transferred to the intermediate state D, designated "YES," upon reaching the minimum time period. If the minimum time period is not reached, by virtue of a switching device 16 being activated before the expiration of the minimum time period, or by the receiving unit 10 receiving a transmission signal, the state of the identification transmitter 1 remains in state A, designated "NO."

[0032] Switching state D describes a state of the identification transmitter 1 in which both the motion sensor 13 and the switching means 16, the receiving unit 10, the timer in the microcontroller 11, and the microcontroller 11 itself are activated. Both the time measured by the timer until the minimum time is reached and the time after which the switching means 16 were last actuated can be reset. If the switching state D of the identification transmitter 1 reaches the minimum time, the switching state D is transferred to the intermediate state B, designated "YES." If the minimum time is not reached, after resetting the motion sensor 13 and the switching means 16, the switching state D of the identification transmitter 1 can be transferred back to the switching state A, designated "NO." The query as to whether the minimum time has been reached is designated by Y.

[0033] Intermediate state B describes a state of the identification transmitter 1 in which the motion sensor 13 and the switching means 16 are activated, while the receiving unit 10, the timer in the microcontroller 11, and the microcontroller 11 itself are deactivated. A quiescent current of only 0.4 µA, which must be provided by the energy storage device 12, may be sufficient.

[0034] The receiving unit 10 can also be configured to periodically check for reception of the transmission signal from the transceiver module in the vehicle, whereby this periodic check for reception is also referred to as polling. If polling occurs, the intermediate state C can be reached, in which the motion sensor 13 and the switching means are activated, and the receiving unit 10 and the microcontroller 11 are deactivated. However, the timer in the microcontroller 11 is active to operate the polling.

[0035] If movement of the identification transmitter 1 occurs, the motion sensor 13 can transmit a corresponding signal or a switching device 16 can be activated, represented by query Z. If the motion sensor detects movement of the identification transmitter 1 and / or a switching device 16 on the identification transmitter 1 is activated, the intermediate state B or intermediate state C can be converted back to the switching state D, indicated by "YES." If the identification transmitter 1 remains in the intermediate state B or intermediate state C, query Z is indicated by "NO."

[0036] The invention is not limited in its implementation to the preferred embodiment described above. Rather, a number of variants are conceivable, which utilize the presented solution even in fundamentally different embodiments. All features and / or advantages apparent from the claims, the description, or the drawings, including structural details, spatial arrangements, and method steps, may be essential to the invention both individually and in a wide variety of combinations. List of reference symbols 1 identification transmitter 10 Receiving unit 11 microcontrollers 12 energy storage units 13 Motion sensor 14 RF module 15 Antenna 16 switching devices 17 Receiving coil A switching state B Intermediate state C Intermediate state D Switching state X Query reaching minimum time in switching state A Y query reaching minimum time in switching state D Z Query motion sensor and / or switching device

Claims

[1] Identification transmitter (1) of a locking system of a vehicle, designed to identify an authorized person to unlock and / or start the vehicle, with - a receiving unit (10) designed to receive a transmission signal that can be transmitted by a transmission-reception module in the vehicle, - a microcontroller (11) for controlling the receiving unit (10), and with - an energy storage device (12) for supplying energy to at least the receiving unit (10) and the microcontroller (11), - a motion sensor (13) designed to sense a movement of the identification transmitter (1), wherein - at least the receiving unit (10) can be switched off by the microcontroller (11), - if the motion sensor (13) detects a lack of movement of the identification transmitter (1) for a minimum period of time, characterized byin that the microcontroller (11) is designed to diagnose the motion sensor (13) in such a way that a defect in the motion sensor (13) can be diagnosed by means of the microcontroller (11), wherein the identification transmitter (1) has a manually operable switching means (16), wherein the diagnosis is carried out in such a way that if the switching means (16) is manually operated and the sensing of a movement of the identification transmitter (1) by the motion sensor (13) does not occur, a defect in the motion sensor (13) is diagnosed.

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