JP2012193571A - Electronic key system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic key system which prevents communication breakdown between an electronic key and a vehicle due to battery exhaustion.SOLUTION: Upon reception of a request signal of a vehicle 2, an electronic key 10 driven by electric power from a battery 12 transmits an ID code signal corresponding to the signal. An electronic key system comprises a smart communication system which allows the vehicle 2 to verify the received ID code signal for operating a mounted instrument or permitting the operation of the instrument after verification, and a second communication system which operates the mounted instrument or permits the operation of the instrument through a wireless communication different from this communication mode. The electronic key 10 is provided with a battery voltage measuring part 18 which measures the voltage of a battery 12. When the level of the battery voltage measured by the battery voltage measuring part 18 is lower than a threshold, low voltage bits are set for the ID code signal. When the vehicle 2 receives the ID code having the low voltage bits, the transmission of the request signal is halted thereafter.

Description

  The present invention relates to an electronic key system.

  In the conventional electronic key system, locking / unlocking of the vehicle door, engine starting, and the like are permitted through wireless communication between the electronic key and the vehicle. For example, in the electronic key system disclosed in Patent Document 1, the vehicle includes an in-vehicle antenna that transmits a request signal to the in-vehicle communication area and an out-of-vehicle antenna that transmits the request signal to the out-of-vehicle communication area around the vehicle. The vehicle intermittently transmits a request signal toward a communication area inside and outside the vehicle. When the electronic key entering the communication area inside or outside the vehicle receives the request signal, it transmits a response signal including an ID code. The vehicle permits locking / unlocking of the vehicle door when collation of the ID code included in the response signal from the electronic key existing in the outside communication area is established. On the other hand, the vehicle permits the start of the engine when the verification of the ID code included in the response signal from the electronic key existing in the in-vehicle communication area is established.

JP 2009-143439 A

  The electronic key disclosed in Patent Literature 1 consumes power stored in a built-in battery and performs wireless communication with a vehicle. The electronic key is also provided with a battery remaining amount detection circuit that detects the remaining amount of power stored in the battery. The electronic key transmits the information indicating the remaining battery level detected by the remaining battery level detection circuit in the response signal. The vehicle can check the remaining battery level of the battery built in the electronic key through reception of the response signal. When it is determined that the remaining battery level is low through the reception of the response signal, the vehicle notifies that the remaining battery level is low by causing a light source (LED) provided in the vehicle to shine.

  By the way, in patent document 1, it only alert | reports that the battery remaining charge is falling. Therefore, if the light source is not confirmed, the battery level is not noticed. That is, there is a possibility that the use of the electronic key may be continued without noticing that the remaining battery level is low. As a result, the battery may run out and communication between the electronic key and the vehicle may not be possible.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic key system that suppresses communication between the electronic key and the vehicle due to battery exhaustion being disabled.

  In order to solve the above-mentioned problems, according to the present invention, the electronic key driven by consuming the power of the built-in battery receives a request signal transmitted to a communication area set in the vicinity of the communication master. Then, a response signal corresponding to this signal is transmitted, and the communication master collates the received response signal, and when this collation is established, the various on-board devices are activated or permitted to operate. A communication system and a second communication system for operating or permitting the various on-board devices through wireless communication between the electronic key and the communication master performed in a mode different from the first communication system In the electronic key system, the electronic key includes a battery remaining amount measuring unit that measures a battery remaining amount of the battery, and the battery remaining amount of the battery measured by the battery remaining amount measuring unit is the first. When it is measured that the level is lower than a threshold set to a level at which the second communication is permitted while disabling communication, remaining amount reduction information indicating that is added to the response signal, and the communication The gist is that when the master receives the response signal to which the remaining amount reduction information is added, the master stops the transmission of the request signal thereafter.

  According to this configuration, the electronic key does not receive a request signal from the communication master corresponding to itself when the remaining battery level decreases. That is, the first communication is not established. Therefore, the user cannot operate the device on which the communication master is mounted through the first communication, so that it is easy to recognize that the battery level of the electronic key is low. This can prompt the user to replace the battery early. Therefore, it is possible to suppress the wireless communication via the second communication system performed between the electronic key and the communication master from being disabled due to a decrease in the remaining battery level. Further, since the electronic key does not receive the request signal, transmission of a response signal to this signal is suppressed. Accordingly, battery power consumption can be suppressed.

  According to a second aspect of the present invention, in the electronic key system according to the first aspect, the electronic key stops receiving the request signal after transmitting the response signal to which the remaining amount reduction information is added. This is the gist.

  According to this configuration, the electronic key does not receive this signal even if it can enter a communication area of another communication master that does not correspond to itself and receive a request signal from another communication master. Therefore, since it is not necessary to perform collation for this signal, battery power consumption can be suppressed.

  According to a third aspect of the present invention, in the electronic key system according to the first or second aspect, as the second communication system, the electronic key has an operation switch, and when the operation switch is operated, , Adopting a configuration for transmitting a wireless signal instructing operation of various mounted devices mounted on the communication master, and the electronic key has a level in which the remaining battery level is lower than the threshold in the remaining battery level measuring unit. When measured, the remaining amount reduction information is added to the wireless signal, and when the communication master receives the wireless signal to which the remaining amount reduction information is added, The gist is to stop the transmission and transmit the request signal when the wireless signal to which the remaining amount reduction information is not given is received.

  According to this configuration, wireless communication can be performed even when the remaining battery level is low and the first communication is disabled. When the remaining battery level falls below a predetermined threshold in the remaining battery level measurement unit, information indicating that is given to the wireless signal. In other words, when the remaining battery level does not fall below the predetermined threshold, the wireless signal received by the communication master does not include information indicating that the remaining battery level is low. Therefore, the communication master can check the remaining battery level of the electronic key through transmission / reception of a wireless signal. If it is determined through this communication that the remaining battery level of the electronic key does not fall below a predetermined threshold value, the communication master transmits a request signal. That is, when the transmission of the request signal is stopped, the communication master can determine whether to restart the transmission of the request signal through the transmission / reception of the wireless signal.

  According to a fourth aspect of the present invention, in the electronic key system according to any one of the first to third aspects, the communication master includes an immobilizer communication device that locally transmits a drive radio wave, and the electronic The key includes a transponder communication circuit that converts the driving radio wave from the communication master into starting power, and when the first communication is disabled, the communication master transmits the driving radio wave, and the electronic key is The gist of the invention is to perform the transponder communication for converting the driving radio wave into the starting power and starting up, and operating the various on-board devices or transmitting a radio signal permitting the operation.

  According to this configuration, even when the remaining battery level of the electronic key is so small that other communications cannot be performed, transponder communication can be performed between the communication master and the electronic key. Then, through this transponder communication, the on-board device mounted on the communication master can be operated or permitted to operate.

  According to a fifth aspect of the present invention, in the electronic key system according to any one of the first to fourth aspects, when the communication master stops the transmission of the request signal, a notification to that effect is given. The gist is to provide means.

  According to this configuration, the user can recognize whether smart communication between the communication master and the electronic key is possible only by confirming the information indicated by the notification means.

  In the present invention, it is possible to provide an electronic key system that suppresses communication between the electronic key and the vehicle due to battery exhaustion being disabled.

1 is a block diagram showing a schematic configuration of an electronic key system according to an embodiment. The top view which shows the communication area and engine switch which were set to the vehicle. Explanatory drawing which shows a low voltage detection bit and ID code signal containing it. The sequence chart which shows a smart communication aspect. The sequence chart which shows the smart communication aspect when the battery voltage is falling. The sequence chart which shows a wireless communication aspect. The sequence chart which shows the transponder communication aspect.

Hereinafter, an embodiment embodying an electronic key system according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, the electronic key system 1 includes an electronic key 10 possessed by a driver of the vehicle 2 and an in-vehicle device 20 disposed in the vehicle 2. The vehicle 2 executes or permits door locking / unlocking and engine starting on the condition that wireless communication performed with the electronic key 10 is established. There are three types of wireless communication: smart communication, wireless communication, and transponder communication (hereinafter referred to as trapon communication). That is, the electronic key system 1 is equipped with a smart communication system as a first communication system and a wireless communication system as a second communication system.

<Structure of electronic key>
The electronic key 10 has a wireless communication function, and controls in-vehicle devices as various on-board devices through mutual wireless communication with the in-vehicle device 20. The electronic key 10 includes an electronic key control unit 11 configured by a computer unit including a CPU, ROM, RAM, and the like, and an LF band request signal Srq electrically connected to the electronic key control unit 11 from the in-vehicle device 20. LF receiver 14 and UHF transmitter 13 for transmitting UHF band ID code signal Sid. Further, the electronic key 10 is provided with a battery 12 connected to the electronic key control unit 11. The battery 12 supplies operating power to the electronic key control unit 11 and also supplies operating power to the UHF transmission unit 13 and the LF reception unit 14 via the electronic key control unit 11.

When receiving the request signal Srq transmitted from the in-vehicle device 20, the LF receiving unit 14 demodulates this signal into a pulse signal and outputs the demodulated demodulated signal to the electronic key control unit 11.
The electronic key control unit 11 is provided with a nonvolatile memory 11a made of, for example, an EEPROM. The memory 11a stores the key code of the electronic key 10, the vehicle ID, and the encryption key. The vehicle ID and the encryption key are the same as those stored in the vehicle 2. The key code and vehicle ID are used for verification of the request signal Srq, and the encryption key is used for cryptographic operation of random number data.

  When the electronic key control unit 11 receives the request signal Srq, the electronic key control unit 11 determines whether or not the signal is transmitted from the vehicle corresponding to itself using the key code and the vehicle ID, and uses the encryption key. The random number data included in the signal is calculated. When the received request signal Srq is for itself, the electronic key control unit 11 has a pulse-like ID code signal including the calculation result of the vehicle ID, the key code, and the random number data as shown in FIG. Sid is generated. Then, this signal is output to the UHF transmitter 13. The UHF transmitter 13 converts the input pulse-tone ID code signal Sid into a radio signal and transmits it to the in-vehicle device 20. The series of wireless communication using the electronic key 10 is referred to as smart communication.

  The electronic key 10 includes a lock switch 15 and an unlock switch 16 that are electrically connected to the electronic key control unit 11 and can be operated from the outside. When the lock switch 15 or the unlock switch 16 is operated and an electric signal indicating that is inputted, the electronic key control unit 11 generates a pulse-like wireless signal Swi indicating that the vehicle door is locked or unlocked. . Then, this signal is output to the UHF transmitter 13. The wireless signal Swi has a configuration in which a function code indicating locking and unlocking is added to the configuration of the ID code signal Sid. The UHF transmitter 13 converts the input pulse-like wireless signal Swi into a radio signal and transmits it to the in-vehicle device 20. Note that this series of wireless communication in the electronic key 10 is wireless communication.

  Furthermore, the electronic key 10 includes a transponder communication circuit 17 that is electrically connected to the electronic key control unit 11. The transponder communication circuit 17 includes a coil and an IC chip. When the transponder communication circuit 17 receives a driving radio wave that is locally transmitted in the vicinity of an engine switch operated at the time of starting the engine, an induced power is generated in its coil. The transponder communication circuit 17 consumes the induced power generated in the coil and transmits a transponder response signal (hereinafter referred to as a trap response signal) Str including its own ID code. This trapon response signal Str has the same configuration as the ID code signal Sid. The series of wireless communication using the electronic key 10 is referred to as trapon communication.

  The electronic key control unit 11 is provided with a battery voltage measurement unit 18. The battery voltage measurement unit 18 measures the voltage level of the battery 12. The electronic key control unit 11 is set with a predetermined voltage X as a threshold value for switching between smart communication and trapon communication. The predetermined voltage X is set to a level at which wireless communication is possible. When the voltage level measured by the battery voltage measurement unit 18 is less than the predetermined voltage X, the electronic key control unit 11 transmits a radio signal (ID code signal Sid) to the in-vehicle device 20 as shown in FIG. The low voltage bit is set in the wireless signal Swi and the trappon response signal Str).

  The electronic key control unit 11 is provided with a mode switching unit 19. The operation mode in the electronic key control unit 11 includes a smart communication mode for performing smart communication and a transponder communication mode for performing trapping communication (hereinafter referred to as trapping communication mode). The mode switching unit 19 switches between the smart communication mode and the trapping communication mode according to the voltage level value measured by the battery voltage measuring unit 18. The voltage level for switching the operation mode is set to a predetermined voltage X which is a reference for setting the low voltage bit. The electronic key control unit 11 disables trapping communication with the in-vehicle device 20 when the mode switching unit 19 is in the smart communication mode, and smart communication with the in-vehicle device 20 when it is in the trapping communication mode. Is impossible. That is, when the electronic key control unit 11 is in the trapping communication mode, the electronic key control unit 11 does not receive the request signal itself issued from other vehicles as well as the vehicle corresponding to the electronic key control unit 11. Note that wireless communication is possible in both the smart communication mode and the trapon communication mode.

<Configuration of in-vehicle device>
The in-vehicle device 20 includes a computer unit including a CPU, a ROM, a RAM, and the like. As shown in FIG. 1, the in-vehicle device 20 includes an in-vehicle control unit 21 that controls various in-vehicle devices, and an LF transmission unit 24 that is electrically connected to the in-vehicle control unit 21 and transmits an LF band request signal. And a UHF receiver 23 for receiving a response signal in the UHF band.

  As shown in FIG. 1, the in-vehicle control unit 21 automatically locks and unlocks the vehicle door, and a door handle sensor 32 provided on the door handle for detecting whether or not the user touches the door handle. The door lock device 34 is electrically connected. Furthermore, an engine switch 33 that is operated when starting the engine and an engine control device 35 that controls the start of the engine of the vehicle 2 are electrically connected to the in-vehicle control unit 21. The door handle sensor 32 outputs an electrical signal indicating that it has been touched, and the engine switch 33 outputs an electrical signal indicating that it has been operated to the in-vehicle controller 21.

  The in-vehicle control unit 21 includes a non-volatile memory 21a composed of, for example, an EEPROM or the like, and the same vehicle ID and encryption key as the vehicle ID set in the corresponding electronic key 10 are stored in the memory 21a. The encryption key is used for encryption of random number data generated by the in-vehicle control unit 21.

  When the vehicle 2 is stopped and locked, such as when the user gets on the vehicle, the in-vehicle control unit 21 intermittently transmits the request signal Srq from the LF transmission unit 24 to a preset communication area. Here, an in-vehicle communication area indicated by countless points in FIG. 2 and an in-vehicle communication area similarly indicated by hatching in FIG. 2 are set. When receiving the ID code signal Sid corresponding to the previous request signal Srq from the electronic key 10, the UHF receiving unit 23 demodulates this to a pulse signal and outputs the demodulated demodulated signal to the in-vehicle control unit 21.

  When receiving the ID code signal Sid corresponding to the request signal Srq transmitted intermittently to the outside communication area, the in-vehicle control unit 21 reads the received data included in the demodulated signal. The in-vehicle control unit 21 performs collation (external vehicle collation) between the data included in the ID code signal Sid and its own data. When this outside vehicle verification is established, the in-vehicle control unit 21 activates the door handle sensor 32. In this state, when the vehicle-mounted control unit 21 detects a user operation through the door handle sensor 32, the vehicle-mounted control unit 21 operates the door lock device 34.

  Further, the LF transmission unit 24 intermittently transmits the request signal Srq toward the in-vehicle communication area. When the engine as a drive source (not shown) mounted on the vehicle 2 is stopped, the in-vehicle control unit 21 operates when the engine switch 33 is operated in a state in which in-vehicle collation is established using this signal as an opportunity. The engine (internal combustion engine) is operated through the engine control device 35. In addition, this series of wireless communication in the vehicle-mounted control part 21 is set as smart communication, and this series of collation is set as smart collation.

  The in-vehicle control unit 21 performs the same collation processing as the previous smart collation even when the wireless signal Swi is received. When this verification, that is, wireless verification is established, the in-vehicle control unit 21 operates the door lock device 34 based on data included in the wireless signal Swi. Note that this series of wireless communication in the in-vehicle control unit 21 is wireless communication.

  As shown in FIG. 1, the vehicle 2 includes an immobilizer communication device 25 that is electrically connected to the in-vehicle control unit 21. The immobilizer communication device 25 is provided in the vicinity of the engine switch 33 shown in FIG. The vehicle-mounted control unit 21 outputs a command signal to the immobilizer communication device 25, for example, when the brake pedal is depressed while the engine is stopped. The immobilizer communication device 25 transmits a driving radio wave based on a command signal from the in-vehicle control unit 21. This driving radio wave is locally transmitted in the vicinity of the engine switch 33. When the electronic key 10 is held over the engine switch 33, the transponder communication circuit 17 of the electronic key 10 is activated by receiving the driving radio wave. Then, the transponder communication circuit 17 transmits a trappon response signal Str. When receiving the trapon response signal Str, the immobilizer communication device 25 demodulates this signal into a pulse signal and outputs it to the in-vehicle control unit 21. Thereafter, the vehicle-mounted control unit 21 performs a collation process similar to the previous smart collation. When the engine of the vehicle 2 is stopped and the engine switch 33 is operated in a state in which this verification, that is, transponder verification (hereinafter referred to as trapon verification) is established, the in-vehicle control unit 21 passes through the engine control device 35. Start the engine.

  As shown in FIG. 1, the in-vehicle control unit 21 is provided with a mode switching unit 26. As in the electronic key control unit 11, the in-vehicle control unit 21 has a smart communication mode and a trapping communication mode. The mode switching unit 26 switches modes depending on whether or not a low voltage bit is set in the radio signal transmitted from the electronic key 10. When the low voltage bit is set, the mode is switched to the smart communication mode, and when the low voltage bit is not set, the mode is switched to the trapping communication mode. The in-vehicle control unit 21 does not transmit a command signal to the immobilizer communication device 25 when the smart communication mode is set. Accordingly, since the immobilizer communication device 25 does not transmit a driving radio wave, trapping communication with the electronic key 10 is disabled. On the other hand, the in-vehicle control unit 21 does not generate the request signal Srq when the trapon communication mode is set. Smart communication with the electronic key 10 is disabled.

  The in-vehicle device 20 includes a display unit 33a made of, for example, liquid crystal. In this example, the engine switch 33 is provided. The display on the display unit 33a is switched depending on whether the in-vehicle control unit 21 is in the smart communication mode or the trapping communication mode. In the smart communication mode, the in-vehicle control unit 21 causes the display unit 33a to display that the engine switch 33 is an engine switch as shown in FIG. On the other hand, in the trapon communication mode, a mark that prompts the electronic switch 10 to be held over the engine switch 33 is displayed on the display unit 33a as shown by the broken line in FIG.

<Communication mode of mutual wireless communication>
Next, a communication mode of mutual wireless communication performed between the in-vehicle control unit 21 and the electronic key control unit 11 will be described with reference to sequence charts shown in FIGS. Here, it is assumed that the engine is stopped and the vehicle door is locked, and the unlocking mode of the vehicle door will be described as a representative.

  First, smart communication when the battery voltage is sufficient and both the in-vehicle control unit 21 and the electronic key control unit 11 are in the smart communication mode will be described. As shown in FIG. 4, the in-vehicle controller 21 intermittently transmits a request signal Srq from the LF transmitter 24 to the outside communication area in order to check whether or not the electronic key 10 exists around the vehicle ( Step S1). The electronic key control unit 11 recognizes that the battery voltage is sufficient through the battery voltage measurement unit 18 (step S2).

  When the electronic key 10 enters the predetermined area and the request signal Srq is received by the LF receiver 14, the request signal Srq is collated (step S3). When the verification is established, an ID code signal Sid is transmitted to the in-vehicle control unit 21 (step S4).

  When the in-vehicle controller 21 receives the ID code signal Sid from the electronic key 10 through the UHF receiver 23, the in-vehicle controller 21 collates the ID code signal Sid (step S5). And when collation is materialized, operation of in-vehicle equipment is permitted (Step S6). For example, when the door handle sensor 32 is operated in a state where this verification is established, the vehicle door is unlocked through the door lock device 34.

  Next, smart communication performed between the battery voltage when the communication mode of the in-vehicle control unit 21 and the electronic key control unit 11 is switched from the smart communication mode to the trapping communication mode will be described. As shown in FIG. 5, the in-vehicle controller 21 causes the request signal Srq to be intermittently transmitted to a predetermined communication area (step S <b> 11). The electronic key control unit 11 recognizes a voltage drop through the battery voltage measurement unit 18 (step S12).

  When receiving the request signal Srq, the electronic key control unit 11 collates the request signal Srq (step S13). When the verification is established, the electronic key control unit 11 transmits the ID code signal Sid including the low voltage bit to the in-vehicle control unit 21 (step S14). After transmitting the ID code signal Sid including the low voltage bit, the electronic key control unit 11 shifts to the trapping communication mode (step S15).

  When receiving the ID code signal Sid including the low-voltage bit, the in-vehicle control unit 21 performs verification of the ID code signal Sid (step S16). And when collation is materialized, operation of in-vehicle equipment is permitted (Step S17). The vehicle-mounted control unit 21 shifts to the trapping communication mode after the vehicle-mounted device is activated or after a predetermined time has elapsed from step S17 (step S18).

  Next, wireless communication performed between the in-vehicle control unit 21 and the electronic key control unit 11 when the communication mode is switched from the trapping communication mode to the smart communication mode will be described. It is assumed that the voltage of the battery 12 provided in the electronic key 10 in this wireless communication is equal to or higher than a predetermined voltage X sufficient for performing smart communication by battery replacement or the like.

  The electronic key control unit 11 recognizes that the battery voltage is sufficient through the battery voltage measurement unit 18 (step S21). When the lock switch 15 or the unlock switch 16 is operated (step S22), the electronic key control unit 11 transmits a wireless signal Swi indicating that (step S23). After transmitting the wireless signal Swi, the electronic key control unit 11 shifts to the smart communication mode (step S24).

  When receiving the wireless signal Swi, the in-vehicle control unit 21 performs collation of this signal (step S25). And when collation is materialized, an in-vehicle device is operated according to a control code contained in wireless signal Swi (Step S26). Thereafter, the in-vehicle control unit 21 shifts to the smart communication mode (step S27).

  Note that the battery 12 provided in the electronic key 10 when the lock switch 15 or the unlock switch 16 is operated in a state where the low voltage of the battery 12 is not notified to the vehicle 2 (the vehicle-mounted control unit 21) by smart communication. When the lock switch 15 or the unlock switch 16 is operated when the voltage is less than the predetermined voltage X, the electronic key control unit 11 transmits the wireless signal Swi including the low voltage bit. About the process of the vehicle-mounted control part 21 and the electronic key control part 11 after transmission of the wireless signal Swi containing this low voltage bit, it becomes the process similar to the process after step S14 shown in FIG.

  Next, trapon communication when both the in-vehicle control unit 21 and the electronic key control unit 11 are in the trapon communication mode will be described. The vehicle-mounted control unit 21 transmits a driving radio wave toward a local area near the engine switch 33 (step S31). When the transponder communication circuit 17 receives the drive radio wave and obtains drive power, the transponder communication circuit 17 transmits a trappon response signal Str (step S32).

  When receiving the trappon response signal Str, the in-vehicle controller 21 collates this signal (step S33). And when collation is materialized, operation of in-vehicle equipment is permitted (Step S34). For example, if the engine switch 33 is operated in a state where this verification is established, the engine is started through the engine control device 35.

  It should be noted that when the battery voltage is recovered by replacing the battery 12 of the electronic key 10 that has shifted to the trapping communication mode, that is, the battery 12 whose battery voltage has dropped, the trapping of the in-vehicle control unit 21 and the electronic key control unit 11 is restored. The communication mode is maintained. Switching from the trapping communication mode to the smart communication mode in the mode switching units 19 and 26 of the in-vehicle control unit 21 and the electronic key control unit 11 is performed only by wireless communication. Thus, by switching the mode with wireless communication as an opportunity, it becomes easier for the user to recognize that the mode has been switched.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) The electronic key control unit 11 is provided with a battery voltage measurement unit 18 that measures the battery voltage of the battery 12. When the electronic key control unit 11 receives the request signal Srq from the in-vehicle control unit 21 when the battery voltage is less than the predetermined voltage X, the electronic key control unit 11 displays a low voltage bit indicating that in the ID code signal Sid corresponding thereto. Decided to set. Thereby, the vehicle-mounted control part 21 can recognize whether the battery voltage of the battery 12 provided in the electronic key 10 is falling. When a low voltage bit is set in the received ID code signal Sid, transmission of the subsequent request signal Srq is stopped. As a result, the electronic key control unit 11 in which the battery voltage is lowered does not receive the request signal Srq. Accordingly, it is not necessary to transmit an ID code signal corresponding to this signal, so that battery power consumption can be suppressed. As a result, it can suppress that a battery voltage falls until other communication, for example, wireless communication, becomes impossible.

  (2) The electronic key control unit 11 stops receiving the request signal Srq when the battery voltage of the battery 12 is less than the predetermined voltage X. As a result, the electronic key control unit 11 does not receive a request signal from a vehicle that does not correspond to itself. Therefore, since it is not necessary to perform collation with respect to this signal, it is possible to suppress a decrease in battery voltage.

  (3) When the battery voltage of the battery 12 becomes less than the predetermined voltage X, the electronic key control unit 11 sets a low voltage bit indicating that in the wireless signal Swi. Thereby, the vehicle-mounted control part 21 can recognize whether the battery voltage of the battery 12 provided in the electronic key 10 is falling through reception of the wireless signal Swi. And the vehicle-mounted control part 21 was made to transmit request signal Srq, when the battery voltage of the battery 12 is not falling. Therefore, when the smart communication is disabled, the user can resume the restart of the smart communication through the wireless communication.

  (4) The vehicle 2 has an immobilizer communication device 25 that transmits a drive radio wave, and the electronic key 10 has a transponder communication circuit 17 that converts the drive radio wave into starting power and consumes the power to transmit a trap response signal Str. Provided. As a result, the electronic key control unit 11 can perform wireless communication with the in-vehicle control unit 21 even when the battery voltage of the battery 12 decreases.

  (5) The display unit 33 a is provided in the engine switch 33. The display unit 33a displays a mark that prompts the user to hold the electronic key 10 when smart communication is disabled. Thereby, it can be notified to the user that the smart communication between the electronic key control unit 11 and the in-vehicle control unit 21 is impossible and the wireless communication is possible by holding the electronic key 10.

In addition, you may change the said embodiment as follows.
-In above-mentioned embodiment, when the electronic key control part 11 recognizes the fall of the battery voltage in the battery 12, after transmitting the ID code signal Sid which set the low voltage bit, not only the request signal of the vehicle corresponding to itself but others However, it is not always necessary to switch to the trapping communication mode so that the request signal is not received. Since the request signal Srq is not transmitted from the vehicle corresponding to itself, the number of times the electronic key control unit 11 receives the request signal Srq decreases. Therefore, a decrease in the battery voltage of the battery 12 can be suppressed without switching the communication mode in the electronic key control unit 11 in this way.

  In the above embodiment, the vehicle-mounted control unit 21 that is set to the trapping communication mode shifts to the smart communication mode through reception of the wireless signal Swi in which the low voltage bit is not set. However, switching to this communication mode is not limited to wireless communication. For example, when the battery voltage is lowered, a low voltage bit is set in the trapping response signal Str transmitted by the electronic key control unit 11. In this way, the in-vehicle controller 21 can shift to the smart communication mode through reception of the trappon response signal Str in which the low voltage bit is not set.

  In the above embodiment, the electronic key control unit 11 includes the battery voltage measurement unit 18 that measures the battery voltage as the battery remaining amount measurement unit of the battery 12, but may be a measurement unit that can measure the battery remaining amount of the battery 12. For example, the battery voltage is not limited to the measurement. For example, the battery remaining amount may be measured by measuring a current value, a battery temperature, or the like. Further, the remaining battery level measurement unit may not be provided in the electronic key control unit 11. That is, it is only necessary that the electronic key 10 is provided so as to transmit the measured information to the electronic key control unit 11. Even when configured in this manner, the same effects as those of the above-described embodiment can be obtained.

  In the above embodiment, the display unit 33a displays a mark that prompts the user to hold the electronic key 10 when smart communication is disabled. However, this is not limited to the mark but may be a character indicating that the electronic key 10 is held over. Moreover, what is necessary is just not only the display in the display part 33a but alerting | reporting means, such as LED, by the light-emission color. Even in the case of such a configuration, it is possible to prompt the user for trapon communication.

  In the above-described embodiment, the electronic key system in which the electronic key 10 performs mutual wireless communication with the vehicle 2 has been described. However, the object with which the electronic key 10 performs mutual wireless communication, that is, the communication master is other than the vehicle 2. May be. For example, an electronic key system that performs mutual wireless communication between the electronic key 10 and a house may be used. In this case, the entrance door is provided with a door handle sensor and a door lock device. Then, when mutual wireless communication is established, the door lock device is activated when contact is detected by the door handle sensor. Even in the case of such a configuration, it is possible to obtain the same effect as the above embodiment.

  In the above embodiment, when the voltage of the battery 12 is equal to or higher than the predetermined voltage X, that is, when the electronic key control unit 11 and the in-vehicle device 20 are in the smart communication mode, the trap communication between the two is disabled. However, this may be permitted. That is, when the user actively requests trapping communication by holding the electronic key 10 over the engine switch 33 and operating the switch 33, the communication is performed even if the voltage of the battery 12 is equal to or higher than the predetermined voltage X. You may allow it.

  In the above embodiment, the smart communication is described in which the signal transmitted from the vehicle 2 is the request signal Srq and the signal transmitted from the electronic key 10 is the ID code signal Sid. It can also be applied to communication. For example, when the request signal Srq is composed of two signals of a wake signal and a challenge signal, the ID code signal Sid is composed of two signals of an ack signal and a response signal, and the request signal Srq is a wake signal and a vehicle. When the ID signal and the challenge signal are composed of three signals, the ID code signal Sid may be composed of an ACK signal, an ACK signal, and a response signal. In the case of two signals, the wake signal and the ACK signal correspond to the challenge signal and the response signal, respectively. In the case of three signals, the wake signal and the ACK signal correspond to the vehicle ID signal and the ACK signal, respectively, and the challenge signal and the response signal correspond to each other. Even with such smart communication, it is possible to obtain the same effects as in the above embodiment. When the ID code signal Sid is composed of a plurality of signals, it is desirable to set the low voltage bit as a signal that is finally transmitted to the vehicle 2, in this case, a response signal.

DESCRIPTION OF SYMBOLS 1 ... Electronic key system, 2 ... Vehicle, 10 ... Electronic key, 11 ... Electronic key control part, 11a, 21a ... Memory, 12 ... Battery, 13 ... UHF transmission part, 14 ... LF reception part, 15 ... Lock switch, 16 DESCRIPTION OF SYMBOLS ... Unlock switch, 17 ... Transponder communication circuit, 18 ... Battery voltage measurement part, 19 ... Mode switching part, 20 ... In-vehicle machine, 21 ... In-vehicle control part, 23 ... UHF reception part, 24 ... LF transmission part, 25 ... Immobilizer Communication device, 26 ... mode switching unit, 32 ... door handle sensor, 33 ... engine switch, 33a ... display unit, 34 ... door lock device, 35 ... engine control device.

Claims (5)

When the electronic key that consumes the power of the built-in battery is driven and receives a request signal transmitted to a communication area set in the vicinity of the communication master, the electronic key transmits a response signal corresponding to the signal, and the communication master The received response signal is collated, and when this collation is established, the first communication system that activates or permits the operation of various on-board devices and the first communication system are performed in a different manner. In the electronic key system including the second communication system that operates or permits the various on-board devices through wireless communication between the electronic key and the communication master,
The electronic key includes a battery remaining amount measuring unit that measures a remaining battery amount of the battery, and the battery remaining amount of the battery measured by the battery remaining amount measuring unit disables the first communication. If it is measured that the level is lower than the threshold set for the level allowing the second communication, the response signal is provided with remaining amount reduction information indicating that,
When the communication master receives the response signal to which the remaining amount reduction information is added, the communication master stops the subsequent transmission of the request signal. The electronic key system according to claim 1.
The electronic key system, wherein the electronic key stops receiving the request signal after transmitting the response signal to which the remaining amount reduction information is added. The electronic key system according to claim 1 or 2,
As the second communication system, the electronic key includes an operation switch, and when the operation switch is operated, a wireless signal is transmitted to instruct operation of various mounted devices mounted on the communication master. And the electronic key gives the remaining amount information to the wireless signal when the remaining battery level is measured by the remaining battery level measurement unit to be lower than the threshold value.
When the communication master receives the wireless signal to which the remaining amount reduction information is added, the communication master stops the subsequent transmission of the request signal and transmits the wireless signal to which the remaining amount reduction information is not added. An electronic key system for transmitting the request signal when received. The electronic key system according to any one of claims 1 to 3,
The communication master includes an immobilizer communication device that locally transmits a driving radio wave, and the electronic key includes a transponder communication circuit that converts the driving radio wave from the communication master into activation power.
When the first communication is disabled, the communication master transmits a driving radio wave, and the electronic key is activated by converting the driving radio wave into starting power and operates or permits the various mounted devices. Electronic key system that performs transponder communication to transmit wireless signals. In the electronic key system according to any one of claims 1 to 4,
When the communication master stops transmission of the request signal, the communication master includes an informing means for informing that effect.

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