JP2011153420A - Electronic key system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve security by suppressing illegal communication between an electronic key and a vehicle using a relay machine in an electronic key system. <P>SOLUTION: A communicable area is limited to a second communication area 42 while including the position of the electronic key 10 discriminated by the arrival direction of a response signal. When radio wave is relayed by the relay machine 101, a receiving antenna 102 and a transmitting antenna 107 must be installed in the second communication area 42. Therefore, both antennas 102, 107 are positioned close to each other, and jamming occurs in the relay machine 101. When the receiving antenna 102 and the transmitting antenna 107 are installed at positions apart from each other, for example, the receiving antenna 102 comes out of the second communication area 42, and the receiving antenna cannot receive a request signal transmitted to the second communication area 42. Consequently, illegal communication through the relay machine 101 can be suppressed, and the security of the electronic key system can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic key system capable of unlocking a vehicle door and starting an engine by wireless communication.

  In the conventional electronic key system, when ID code verification is established through transmission / reception of various signals including the ID code between the electronic key and the vehicle, it is possible to lock and unlock the vehicle door lock, start the engine, and the like. For example, in the electronic key system disclosed in Patent Document 1, the vehicle includes an in-vehicle antenna that forms a communication area inside the vehicle and an outside antenna that forms a communication area around the vehicle. When ID code verification (external vehicle verification) is established through communication between the electronic key existing in the vehicle outside communication area and the vehicle, control for switching the lock state of the door lock is performed. On the other hand, when ID code verification (in-vehicle verification) is established through communication between the electronic key existing in the in-vehicle communication area and the vehicle, engine start is permitted.

  By the way, with recent developments in communication technology, there is a risk of unauthorized communication between an electronic key carried by a user located far away from the vehicle and the vehicle. That is, for example, a relay that relays radio waves between the electronic key and the vehicle is provided, and communication between the electronic key and the vehicle is established even when the electronic key is located far away from the vehicle outside communication area. The trick to let it be assumed.

For example, as disclosed in Patent Document 2, various countermeasures have been conventionally taken against unauthorized communication using such a repeater.
For example, the applicant of the present application has studied the adoption of a configuration that suppresses unauthorized radio wave relaying by a repeater by transmitting and receiving signals in the same frequency band between the vehicle and the electronic key, in order to solve the above problems. ing. Specifically, as shown in FIG. 7, the repeater 101 includes a request signal relay unit 110 and a response signal relay unit 111. The request signal relay unit 110 includes a receiving antenna 102 provided on the vehicle 121 side for receiving a request signal from the vehicle 121 and a transmission provided on the electronic key 122 side to transmit the received request signal to the vicinity of the electronic key 122. And an antenna 103. The reception antenna 102 and the transmission antenna 103 are connected via a connection line 105.

  Further, the response signal relay unit 111 is provided on the vehicle 121 side in order to transmit the received response signal to the vehicle 121 side, and the reception antenna 108 provided on the electronic key 122 side to receive the response signal from the electronic key 122. The transmission antenna 107 is provided. The reception antenna 108 and the transmission antenna 107 are connected via a connection line 106.

  Both connection lines 105 and 106 are provided with amplifier circuits 104 and 109, respectively. Amplifier circuits 104 and 109 amplify the signals received by receiving antennas 102 and 108 and transmit the amplified signals to transmitting antennas 103 and 107 side.

  According to the above configuration, the repeater 101 can transmit the request signal received via the reception antenna 102 from the transmission antenna 103 to the electronic key 122. Further, the repeater 101 can receive a response signal from the electronic key 122 corresponding to the request signal via the reception antenna 108 and transmit the received response signal to the vehicle 121 from the transmission antenna 107. Therefore, even when the electronic key 122 exists at a position away from the vehicle 121, the relay 101 can communicate between the vehicle 121 and the electronic key 122.

  Note that a pair of transmission / reception antennas may be provided on the connection lines 105 and 106 so that the request signal and the response signal can be transmitted and received wirelessly. As a result, the receiving antenna 102 and the transmitting antenna 107 provided on the vehicle 121 side and the transmitting antenna 103 and the receiving antenna 108 provided on the electronic key 122 side are installed at remote locations, and radio wave relay can be performed wirelessly. It becomes.

  When the repeater 101 configured as described above transmits and receives a request signal and a response signal in the same frequency band (UHF band) between the vehicle 121 and the electronic key 122, the following phenomenon occurs. That is, a request signal from the vehicle 121 is transmitted from the transmission antenna 103 to the electronic key 122 via the reception antenna 102 and the amplification circuit 104. The electronic key 122 returns a response signal in response to the request signal from the transmission antenna 103. The reception antenna 108 receives this response signal. At this time, the receiving antenna 108 receives not only the response signal but also the request signal from the transmitting antenna 103. The request signal received by the reception antenna 108 is transmitted as a jamming radio wave from the transmission antenna 107 via the connection line 106. The request signal from the vehicle 121 interferes with the jamming radio wave, and the interference request signal is transmitted from the transmission antenna 103 to the electronic key 122. The electronic key 122 does not send back a response signal, assuming that the mixed request signal is not a regular request signal. Further, even if a response signal is returned from the electronic key 122, the interfering request signal emitted from the transmission antenna 103 for the response signal becomes a jamming radio wave. As described above, the reception antennas 102 and 108 receive and circulate the request signals or response signals that are not supposed to occur, thereby generating jamming radio waves and preventing the establishment of unauthorized communication between the vehicle 121 and the electronic key 122. .

JP 2007-170162 A JP 2006-118886 A

  However, there are the following concerns regarding radio wave relay measures using signals in the same frequency band. That is, in the repeater 101, it is conceivable to prevent the reception antennas 102 and 108 from receiving jamming radio waves from the transmission antennas 103 and 107 by providing both units 110 and 111 sufficiently apart. In this way, when the circulation of radio waves and the transmission / reception of jamming radio waves are avoided, there is a possibility that unauthorized communication by the repeater 101 may be performed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electronic key system that further improves security by suppressing unauthorized communication between an electronic key using a repeater and a vehicle. It is to provide.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to the first aspect of the present invention, a response signal having the same frequency band as that of at least one of the two request signals is transmitted in response to the first request signal and the second request signal from the vehicle side carried by the user. An electronic key, which is mounted on the vehicle and transmits the first request signal in a first communication area set inside and outside the vehicle to check whether the electronic key exists outside the vehicle interior When the response signal to the first request signal is detected, the second request signal is transmitted within a second communication area set narrower than the first communication area, and both When it is determined that the response signals with respect to the request signal are appropriate, an in-vehicle device capable of unlocking the vehicle door and starting the vehicle engine, and a response signal with respect to the first request signal provided in the vehicle Based on Key position discriminating means for discriminating the position of the electronic key with respect to the vehicle, and the in-vehicle device includes a position of the discriminated electronic key based on a discrimination result of the key position discriminating means. The gist is to set.

  An unauthorized communication means for communicating with an electronic key located far away from the vehicle by using a relay that relays the radio waves of both the request signal and the response signal transmitted and received between the vehicle and the electronic key is considered. Generally, a repeater is a request signal receiving antenna that receives a request signal from a vehicle, a request signal transmitting antenna that transmits the request signal to the electronic key, and a response that receives a response signal from the electronic key. A signal receiving antenna; and a response signal transmitting antenna that transmits the response signal to the vehicle side.

  Here, when a request signal and a response signal in the same frequency band are transmitted and received between the vehicle and the electronic key, the request signal receiving antenna of the repeater receives the response signal from the response signal transmitting antenna carelessly. There is a case. Similarly, the response signal receiving antenna may inadvertently receive the request signal from the request signal transmitting antenna. Signals that are inadvertently received by the receiving antenna as described above are transmitted from both transmitting antennas and act as jamming radio waves for the normal request signal and response signal. This prevents communication between the vehicle and the electronic key via the repeater.

  However, for example, when the request signal receiving antenna and the response signal transmitting antenna, and the response signal receiving antenna and the request signal transmitting antenna are sufficiently separated so as to disable transmission and reception of signals between the two antennas, Interfering radio waves are not generated, and radio relaying by a repeater is possible.

  According to the above configuration, the communication area is limited from the first communication area to the second communication area in a manner that includes the position of the electronic key determined by the key position determination means. Therefore, when radio waves are relayed by the repeater, it is necessary to install a request signal receiving antenna and a response signal transmitting antenna in the second communication area. In this case, both antennas are close to each other. For this reason, jamming radio waves are generated in the repeater. On the other hand, when the request signal receiving antenna and the response signal transmitting antenna are provided at positions separated from each other, for example, the request signal receiving antenna is removed from the second communication area, and the second signal transmitted to the second communication area is transmitted. The request signal cannot be received. Thereby, unauthorized communication between the vehicle and the electronic key via the relay device can be suppressed, and the security of the electronic key system can be further improved.

  According to a second aspect of the present invention, in the electronic key system according to the first aspect, the key position determining means determines the position of the electronic key through detection of the arrival direction of the response signal with respect to the first request signal. Then, the gist of the in-vehicle device is to form the second communication area along the arrival direction and transmit the second request signal to the area.

  According to this configuration, the position of the electronic key is determined through detection of the arrival direction of the response signal with respect to the first request signal. Therefore, when the communication area is limited to the second communication area, the second communication area may be set based on the arrival direction. As a result, the second communication area can be set to a narrower area including the position of the electronic key, and radio wave relaying by the repeater can be more reliably suppressed.

  According to a third aspect of the present invention, in the electronic key system according to the first or second aspect, a transmission timing signal including transmission timing information of the response signal from the in-vehicle device to the electronic key, and the electronic key to the electronic key. The electronic key or the in-vehicle device that has received the transmission timing signal when a transmission timing signal including at least one of the transmission timing information of the two request signals is transmitted to the in-vehicle device is included in the transmission timing signal Based on the transmission timing information of at least one of the response signal and the two request signals, the gist of transmitting at least one of the response signal and the two request signals at a different transmission timing for each communication. Yes.

  In the above repeater, for example, both reception antennas are switched between a receivable state and a receivable state in order to prevent reception of unnecessary request signals and response signals through analysis of transmission timings of request signals and response signals. In this case, communication between the vehicle and the electronic key can be performed via the repeater without generating jamming radio waves.

  According to the above configuration, the transmission timing signal is transmitted in one direction between the in-vehicle device and the electronic key. The transmission timing signal includes transmission timing information of at least one of the response signal and the two request signals. Therefore, the transmission timing of the request signal and the response signal can be varied for each communication using the transmission timing signal.

  Therefore, even if the transmission timing of the request signal and the response signal is analyzed, in the next communication, at least one of the request signal and the response signal is transmitted and received at a timing different from the analyzed transmission timing. Even if the means for analyzing the transmission timing is used, the request signal or the response signal is not relayed as a complete signal by the relay device, and unauthorized communication between the vehicle and the electronic key via the relay device can be suppressed. Thereby, the security of the electronic key system can be further improved.

According to a fourth aspect of the present invention, in the electronic key system according to any one of the first to third aspects,
While transmitting both said request signals based on the instruction | command from the said vehicle equipment, it is equipped with the some transmission antenna arrange | positioned at the said vehicle, The said key position discrimination means is the position of the said electronic key on the basis of each said transmission antenna And the in-vehicle device forms the second communication area including the position of the electronic key determined through the response signal to the first request signal transmitted from each transmission antenna, and The gist of the invention is to switch the transmitting antenna that transmits the request signals during communication with the electronic key.

  According to this configuration, a plurality of transmission antennas are provided, and a plurality of second communication areas are formed for the same electronic key. Then, when communicating with the electronic key, the second communication area is switched by switching the transmission antenna that transmits the request signal.

  By the way, in the said repeater, the structure which does not generate | occur | produce a jamming electric wave even if both antennas are approached by giving directivity to the antenna for request signal reception and the antenna for response signal transmission is assumed. Specifically, the request signal receiving antenna receives only signals from the in-vehicle device (transmission antenna), and the response signal transmitting antenna transmits signals only to the in-vehicle device (transmission antenna). As a result, a signal from the response signal transmitting antenna is not received by the request signal receiving antenna, and no interference wave is generated.

  However, according to the above configuration, since a plurality of transmission antennas are provided, a request signal receiving antenna having directivity cannot receive all the request signals coming from the plurality of transmission antennas. Therefore, unauthorized communication between the vehicle and the electronic key via the relay can be suppressed. Thereby, the security of the electronic key system can be further improved.

  According to the present invention, in the electronic key system, it is possible to further improve security by suppressing unauthorized communication between the electronic key using the relay device and the vehicle.

The block diagram of the electronic key system in 1st Embodiment. The timing chart of the various signals in 1st Embodiment. FIG. 2 is a top view of the vehicle at the time of external communication in the first embodiment. The top view of the vehicle at the time of the vehicle outside communication by the relay machine in 1st Embodiment. The vehicle top view at the time of the communication outside a vehicle by the relay machine in 2nd Embodiment. The vehicle top view at the time of the communication outside a vehicle in other embodiment. The block diagram of the relay machine which relays an electromagnetic wave between a vehicle and an electronic key.

(First embodiment)
Hereinafter, a first embodiment in which an electronic key system according to the present invention is embodied 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. Mutual communication is automatically performed between the electronic key 10 and the vehicle-mounted device 20, and the door lock / unlock and the engine start are controlled on the condition that the mutual communication is established outside and inside the vehicle.

<Electronic key>
The electronic key 10 has a wireless communication function, and controls various in-vehicle devices through mutual 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, a ROM, a RAM, and the like, and a UHF reception unit that is electrically connected to the electronic key control unit 11 and receives a request signal in the UHF band. 12, a UHF transmission unit 13 that transmits a response signal in the UHF band, and an LF reception unit 14 that receives a request signal in the LF band.

  Here, the request signal is transmitted from the in-vehicle device 20 and the response signal is transmitted from the electronic key 10 in response to the request signal. Each of the request signal and the response signal is not a single signal but a plurality of signals. That is, the request signal includes a wake signal Swk, a vehicle ID signal Svi, and a challenge signal Scc, and the response signal includes an ack signal Sac and a response signal Sre. The transmission timing signal Sti is transmitted from the in-vehicle device 20 between the wake signal Swk and the vehicle ID signal Svi. The wake signal Swk corresponds to the first request signal, and the vehicle ID signal Svi and the challenge signal Scc correspond to the second request signal.

  When receiving the LF band wake signal Swk transmitted from the in-vehicle device 20, the LF receiving unit 14 demodulates the wake signal Swk into a pulse signal and outputs the demodulated demodulated signal to the electronic key control unit 11. When the electronic key control unit 11 recognizes that the radio signal received based on the demodulated signal is the wake signal Swk, the electronic key control unit 11 returns the UHF band ACK signal Sac to the vehicle 2 side via the UHF transmission unit 13.

  As shown in FIG. 1, the electronic key control unit 11 is provided with a non-volatile memory 11a made of, for example, an EEPROM or the like, and an ID code and an encryption key unique to the electronic key 10 are stored in the memory 11a. Has been. The encryption key is used for decrypting an encrypted transmission timing signal Sti, which will be described later, and for encrypting a challenge code. The encryption key used for decrypting the transmission timing signal Sti and the encryption key used for encrypting the challenge code may be the same key or different keys.

  Upon receiving the UHF band vehicle ID signal Svi, the challenge signal Scc, and the transmission timing signal Sti transmitted from the in-vehicle device 20, the UHF receiver 12 demodulates these signals Svi, Scc, Sti into pulse signals and demodulates them. The demodulated signal is output to the electronic key control unit 11. When the demodulated signal is input from the UHF receiver 12, the electronic key controller 11 reads the received data included in the demodulated signal. When the electronic key control unit 11 recognizes that the received radio signal is the transmission timing signal Sti based on the received data, the electronic key control unit 11 transmits the vehicle ID signal Svi and the challenge signal Scc based on the transmission timing pattern included in the signal Sti. To do. The transmission timing pattern will be described in detail later.

  When the electronic key control unit 11 recognizes that the received radio signal is the vehicle ID signal Svi based on the received data, the electronic key control unit 11 returns the UHF band ACK signal Sac to the vehicle 2 side via the UHF transmission unit 13.

  When the electronic key control unit 11 recognizes that the received radio signal is the challenge signal Scc based on the received data, the electronic key control unit 11 outputs a response signal Sre including the ID code registered in the memory 11 a to the UHF transmission unit 13. Then, the UHF transmission unit 13 returns a UHF band response signal Sre to the vehicle 2 side.

<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 22 and a UHF transmission / reception unit 28 that are electrically connected to the in-vehicle control unit 21. Yes. The UHF transmission / reception unit 28 is a transmission / reception antenna unit including a UHF transmission unit 23 and an in-vehicle reception unit 24.

  As shown in FIG. 1, the in-vehicle control unit 21 includes an engine switch 33 that is operated when the engine is started, a door lock device 34 that automatically locks and unlocks the vehicle door, and engine start control of the vehicle 2. An engine control device 35 is electrically connected to a door handle sensor 32 that is provided on the door handle and detects whether or not the user touches the door handle.

  As shown in FIG. 3, the LF transmission unit 22 is provided inside the door handle 50 of each vehicle door of the vehicle 2 and in the vehicle. When the wake signal Swk is input from the in-vehicle control unit 21, the LF transmission unit 22 modulates the wake signal Swk into an LF band radio signal, and the radio signal is transmitted to the outside transmission antenna 22a at a preset intermittent period. To the first communication area 41 formed around the vehicle 2. As shown in FIG. 3, the first communication area 41 is formed in a semicircular shape with the bottom side centered on the LF transmitter 22 provided in the door handle 50 along the side of the vehicle. Similarly to the above, the LF transmitter 22 provided in the vehicle transmits a wake signal Swk to a communication area (not shown) formed in the entire vehicle interior.

  Here, since the vehicle-mounted control unit 21 transmits the wake signal Swk at different timings through the LF transmission units 22, only the electronic key 10 exists inside or outside the vehicle based on the return timing of the ACK signal Sac. Instead, it can be determined whether the electronic key 10 outside the vehicle exists in the first communication area 41 formed around which vehicle door.

  The UHF transmission / reception unit 28 is provided in the center of the vehicle and can communicate with the electronic key 10 existing outside and inside the vehicle. Specifically, when the UHF transmission unit 23 constituting the UHF transmission / reception unit 28 receives the transmission timing signal Sti, the vehicle ID signal Svi, and the challenge signal Scc from the in-vehicle control unit 21, the signals Sti, Svi, and Scc are transmitted. It modulates to the radio signal of a UHF band, and transmits to the 2nd communication area 42 via the UHF transmission antenna 23a with the preset intermittent period. The second communication area 42 will be described in detail later. 3, the UHF transmission antenna 23a is integrally configured with the UHF transmission unit 23, and the reception antenna 24a is integrally configured with the in-vehicle reception unit 24.

  Similarly, when the in-vehicle receiving unit 24 constituting the UHF transmitting / receiving unit 28 receives the ACK signal Sac transmitted from the electronic key 10 via the receiving antenna 24a, the in-vehicle receiving unit 24 demodulates this signal into a pulse signal, and controls this demodulated signal in the in-vehicle control. To the unit 21. Here, the receiving antenna 24a is configured as an array antenna in which a plurality of antenna elements are arranged. Therefore, the arrival direction of the ACK signal Sac can be calculated by the adaptive array antenna system. The adaptive array antenna method is a method of determining the signal arrival direction of the received signal based on the amplitude and phase difference of the received radio wave received by each antenna element of the receiving antenna 24a. Examples of this calculation include a beam former method, a Capon method, a linear prediction method, a minimum norm method, a MUSIC method, and an ESPRIT method. Therefore, the in-vehicle control unit 21 can calculate the signal arrival direction of the ACK signal Sac returned from the electronic key 10 according to the wake signal Swk received by the receiving antenna 24a.

  The in-vehicle controller 21 sets the second communication area 42 based on the signal arrival direction of the ACK signal Sac returned from the electronic key 10. Specifically, when the arrival direction of the ACK signal Sac returned from the electronic key 10 is calculated to be a direction along the arrow 51 in FIG. 3, it is within the first communication area 41 and on the line of the arrow 51. It can be estimated that the electronic key 10 exists. In this case, the second communication area 42 is formed so as to include the electronic key 10 existing in the first communication area 41 from the UHF transmission / reception unit 28, as shown in FIG. The second communication area 42 is formed with a width in a direction orthogonal to the arrow 51 direction from the UHF transmission / reception unit 28. This width increases as the distance from the UHF transceiver unit 28 increases. In addition, since the UHF band radio signal such as the challenge signal Scc is transmitted to the second communication area 42, the second communication area 42 is formed to a position farther from the vehicle 2 than the first communication area 41.

  As described above, the second communication area 42 is formed with a width around the arrow 51, so that the electronic key 10 moves on the arrow 51 due to a signal arrival direction calculation error, movement of the electronic key 10 during communication, or the like. And the challenge signal Scc and the like cannot be received.

  The in-vehicle control unit 21 includes a non-volatile memory 21a made of, for example, an EEPROM or the like, and the memory 21a has the same ID code as the ID code set in the corresponding electronic key 10 and information on transmission timing described later. A transmission timing pattern and an encryption key are stored. The encryption key is used for encrypting the transmission timing signal Sti and calculating a response code. The encryption key used for encrypting the transmission timing signal Sti and the encryption key used for the response code calculation may be the same key or different keys.

  When the response signal Sre transmitted from the electronic key 10 in response to the challenge signal Scc transmitted through the UHF transmitter 23 is received via the in-vehicle receiver 24, the in-vehicle controller 21 is included in the response signal Sre. The ID code is collated with the ID code recorded in the memory 21a. The in-vehicle control unit 21 compares the response code included in the response signal Sre with the response code calculated by itself through the encryption key, and performs response verification.

  If it is determined that the electronic key 10 is present outside the vehicle, if both the above verifications are established, the vehicle door is brought into an unlockable state because the external verification is established. In this unlockable state, the vehicle-mounted control unit 21 unlocks the vehicle door via the door lock device 34 when detecting that the user touches the door handle 50 through the door handle sensor 32.

  On the other hand, when it is determined that the electronic key 10 is present in the vehicle, if both the above verifications are established, it is determined that the vehicle verification is established, and the engine start permission state is set. When the engine switch 33 installed in the vicinity of the driver's seat is operated in the engine start permission state, the operation signal is output to the in-vehicle control unit 21. The vehicle-mounted control unit 21 outputs a command signal to the engine control device 35 when detecting the operation signal in the engine start permission state. Based on the command signal, the engine control device 35 drives a cell motor (not shown) to start engine control.

  Next, the transmission timing of the request signal and the response signal will be described. In brief, the transmission timing of the request signal and the response signal is changed for each communication based on the transmission timing signal Sti transmitted from the vehicle 2 to the electronic key 10. Communication refers to a series of transmission / reception of a request signal and a response signal until in-vehicle verification or external verification is established.

  Hereinafter, the case of outside-vehicle verification will be described. As shown in the upper part of FIG. 2, the in-vehicle control unit 21 sends the LF band wake signal Swk from the LF transmission unit 22 to the first communication in order to check whether or not the electronic key 10 exists in the first communication area 41. The area 41 is intermittently transmitted. The wake signal Swk is a command signal that activates the electronic key 10 in a standby state, and is repeatedly transmitted from the LF transmitter 22 at regular intervals.

  When the electronic key 10 enters the first communication area 41 and receives the wake signal Swk, the electronic key 10 is switched from the standby state to the activated state when the wake signal Swk is received. When the electronic key 10 is normally activated at this time, the electronic key 10 sends back an ACK signal Sac to the vehicle 2 to notify the fact (timing t1). As shown in the lower part of FIG. 2, the in-vehicle control unit 21 performs an operation of receiving the ACK signal Sac by polling performed after transmitting the wake signal Swk.

  At this time, the ACK signal Sac transmitted by the electronic key 10 is set at a transmission timing to reach the in-vehicle receiving unit 24 when the in-vehicle receiving unit 24 is in a reception standby state. And the vehicle-mounted control part 21 will calculate the signal arrival direction of the ACK signal Sac while judging in which 1st communication area 41 the electronic key 10 exists, if the ACK signal Sac is received. And the vehicle-mounted control part 21 sets the 2nd communication area 42 on the basis of the calculated signal arrival direction.

  When the in-vehicle control unit 21 normally receives the ACK signal Sac in response to the wake signal Swk, the in-vehicle control unit 21 ends the polling at the cycle, and thereafter, the authentication communication operation for actually confirming whether the electronic key 10 is genuine. Migrate to At the time of this authentication communication operation, a reception standby state is entered at the timing of actually performing wireless communication with the electronic key 10, specifically at the timing (timing t2, t3) of receiving the ACK signal Sac and the response signal Sre.

  In performing the authentication communication operation, the vehicle-mounted control unit 21 transmits a UHF band transmission timing signal Sti via the UHF transmission unit 23. The transmission timing signal Sti includes information regarding transmission timing such as a request signal and a response signal in the authentication communication operation, that is, a challenge signal Scc, a response signal Sre, and the like.

  As the information regarding the transmission timing included in the transmission timing signal Sti, a different pattern is selected for each transmission of the transmission timing signal Sti. Specifically, the transmission timing is selected as follows. That is, a plurality of types of transmission timing patterns are stored in the memory 21a. The in-vehicle control unit 21 randomly selects a predetermined transmission timing pattern from these transmission timing patterns, and includes information on the transmission timing in the transmission timing signal Sti.

  In order to prevent unauthorized reading of information, the in-vehicle control unit 21 encrypts the transmission timing signal Sti using the encryption key stored in the memory 21a and transmits the transmission timing signal Sti.

  When the electronic key 10 receives the transmission timing signal Sti via the UHF receiving unit 12, the electronic key control unit 11 decrypts the transmission timing signal Sti encrypted using the encryption key stored in the memory 11a. The electronic key control unit 11 recognizes the transmission timing pattern selected on the vehicle 2 side by decoding the transmission timing signal Sti. Here, the encryption key (the key possessed by the electronic key 10 and the vehicle-mounted device 20) used for encryption and decryption of the transmission timing signal Sti is the same. That is, a common key method is adopted as an encryption method between the electronic key 10 and the in-vehicle device 20.

  The in-vehicle control unit 21 transmits the vehicle ID signal Svi and the challenge signal Scc from the UHF transmission unit 23 based on one transmission timing pattern randomly selected from a plurality of types of transmission timing patterns. Specifically, as shown in the upper part of FIG. 2, the vehicle ID signal Svi is transmitted after the time T1 has elapsed from the completion of transmission of the transmission timing signal Sti. The challenge signal Scc is transmitted after the time T2 has elapsed since the completion of the transmission of the vehicle ID signal Svi.

  The electronic key control unit 11 transmits an ACK signal Sac and a response signal Sre from the UHF transmission unit 13 based on the recognized transmission timing pattern. Specifically, as shown in the middle part of FIG. 2, the ACK signal Sac is returned after the time T3 has elapsed since the completion of the reception of the vehicle ID signal Svi. Further, the response signal Sre is transmitted after the time T4 has elapsed since the completion of the reception of the challenge signal Scc. As described above, the transmission timing signal Sti (transmission timing pattern) includes information on the times T1 to T4 during which the various signals Svi, Sac, Scc, and Sre are transmitted as information related to the transmission timing. Here, it is assumed that the transmission completion timing of the signal from the in-vehicle device 20 and the reception completion timing of the same signal of the electronic key 10 are the same timing.

  Upon receiving the vehicle ID signal Svi, the electronic key 10 confirms whether the vehicle 2 is a legitimate vehicle through vehicle ID verification that checks whether the vehicle ID signal Svi is from the vehicle 2 corresponding to the electronic key 10 itself. Determine whether or not. In this way, by performing vehicle ID collation, even if there are a plurality of vehicles around the electronic key 10 and a request signal is received from the plurality of vehicles, the vehicle can only be exchanged with a regular vehicle. Communication after receiving the ID signal Svi can be performed.

  When the electronic key 10 recognizes that the vehicle ID verification has been established, the electronic key 10 returns an ACK signal Sac to the vehicle 2 to notify the fact. As described above, the ACK signal Sac is transmitted after the time T3 has elapsed since the completion of the transmission of the vehicle ID signal Svi. After transmitting the vehicle ID signal Svi, the in-vehicle control unit 21 enters a reception standby state in which the ACK signal Sac can be received. The duration of the reception standby state is set based on the transmission timing of various signals Svi, Sac, Scc, Sre.

  When the vehicle-mounted control unit 21 normally receives the ACK signal Sac after transmitting the vehicle ID signal Svi, the vehicle-mounted control unit 21 recognizes that the vehicle ID verification has been established with the electronic key 10, and the electronic device existing in the first communication area 41. Recognizes that the key 10 is paired with itself. Note that when the vehicle-mounted control unit 21 receives the ACK signal Sac in response to the transmission of the vehicle ID signal Svi, the vehicle-mounted control unit 21 is no longer in the reception standby state.

  When the vehicle-mounted control unit 21 recognizes that vehicle ID verification has been established with the electronic key 10, the vehicle-mounted control unit 21 then transmits a challenge signal Scc from the outside transmission antenna 22 a. The challenge signal Scc includes a challenge code used as a random number and a key number of the electronic key 10 registered on the vehicle 2 side.

  When the electronic key 10 receives the challenge signal Scc from the vehicle 2, the electronic key 10 compares the key number received at this time with the key number registered in itself to determine whether or not it is a communication target. To do. In addition, this number collation is collation which determines the master or sub key kind about the electronic key 10 with which the vehicle equipment 20 is its communication partner. The in-vehicle controller 21 enters the reception standby state again after transmitting the challenge signal Scc.

  The electronic key 10 for which the number verification is established returns a response signal Sre including the ID code and the response code stored in its own memory 11a to the vehicle 2 side. The response code is a code obtained by encrypting a challenge code using a cryptographic key. As described above, the response signal Sre is transmitted after the time T4 has elapsed since the reception of the challenge signal Scc. This response signal Sre is transmitted at a timing reaching the in-vehicle receiving unit 24 when the in-vehicle receiving unit 24 is in a reception standby state.

  When receiving the response signal Sre, the in-vehicle control unit 21 compares the ID code included in the response signal Sre with the ID code stored in its own memory 21a to perform ID verification. Further, when transmitting the challenge signal Scc, the vehicle-mounted control unit 21 also generates a response code by encrypting the challenge code with its own encryption key. Then, when the in-vehicle control unit 21 receives the response signal Sre from the electronic key 10 by the in-vehicle receiving unit 24, the in-vehicle control unit 21 compares the response code of the electronic key 10 with the response code calculated by itself, and executes response verification. And if the vehicle-mounted control part 21 confirms that response collation and ID code collation will be materialized, it will process as collation establishment by this. In this way, when the vehicle outside verification is established, the vehicle door is brought into an unlockable state. Note that in-vehicle verification is basically performed in the same manner as in-vehicle verification. When the in-vehicle verification is established, the engine start permission state is set.

Next, in the electronic key system 1, the mode of the radio wave relay by the relay device of the request signal and the response signal transmitted / received between the vehicle 2 and the electronic key 10 will be described.
The repeater assumed in this example has substantially the same configuration as the repeater 101 described with reference to FIG. Therefore, the mode of the radio wave relay will be described here with reference to the repeater 101 in FIG.

  In the repeater 101 assumed in this example, for example, switching elements are provided in the connection lines 105 and 106, and the connection lines 105 and 106 are switched between a non-energized state and an energized state through on / off control of these switching elements. It is done.

  When the transmission timing of the request signal and the response signal between the vehicle 2 and the electronic key 10 is analyzed, it can be considered that the generation of the jamming radio wave is suppressed by this configuration. Specifically, during transmission of the request signal, the connection line 105 is energized and the connection line 106 is de-energized. During response signal transmission, the connection line 105 is energized and the connection line 106 is de-energized. As a result, the above-described circulation of radio waves and generation of jamming radio waves are suppressed.

  Even when such a repeater 101 is used, in this example, the transmission timing of various signals Svi, Sac... After the signal Sti differs for each communication by the transmission timing signal Sti. Therefore, the relay device 101 cannot relay various signals Svi, Sac... After the transmission timing signal Sti as a complete signal by switching the energization state of the connection lines 105 and 106. Thereby, the radio wave relay between the vehicle 2 and the electronic key 10 by the repeater 101 is prevented.

  However, as described in the above prior art, when both units 110 and 111 of the repeater 101 are provided so as to be unable to transmit / receive signals to each other, there is a possibility that radio waves are relayed without generating jamming waves. was there. However, even in this case, according to this example, it is possible to prevent radio wave relay by the repeater 101.

  Specifically, as shown in FIG. 4, the relay unit 101 assumed here includes both units 110 and 111 as separate units. The reception antenna 102 includes an LF reception antenna 102a that receives a radio signal in the LF band and a UHF reception antenna 102b that receives a radio signal in the UHF band, and the transmission antenna 103 transmits a radio signal in the LF band. The LF transmission antenna 103a and the UHF transmission antenna 103b that transmits a radio signal in the UHF band are configured.

As indicated by the circled numeral 1 in FIG. 4, both units 110 and 111 are provided so as to be unable to transmit and receive signals from each other.
In this case, the LF reception antenna 102 a existing in the first communication area 41 receives the wake signal Swk, and the wake signal Swk is transmitted from the LF transmission antenna 103 a to the electronic key 10 via the connection line 105. In response to this, the electronic key 10 returns an ACK signal Sac. The ACK signal Sac is received by the reception antenna 108, and the ACK signal Sac is transmitted from the transmission antenna 107 to the in-vehicle device 20 via the connection line 106.

  The in-vehicle device 20 forms the second communication area 42 including the transmission antenna 107 based on the signal arrival direction of the calculated ACK signal Sac. However, since the receiving antenna 102 is separated from the transmitting antenna 107, it is not included in the second communication area 42. Therefore, the UHF receiving antenna 102b does not receive the transmission timing signal Sti, the vehicle ID signal Svi, and the challenge signal Scc transmitted to the second communication area 42. Thereby, the radio wave relay between the vehicle 2 and the electronic key 10 by the repeater 101 is prevented.

  In addition, as shown by the circled numeral 2 in FIG. 4, when the receiving antenna 102 is provided at a position in the second communication area 42, an interference wave is generated in the same manner as described above, and the vehicle 2 and the electronic key 10 are The radio relay is prevented.

  In addition, by transmitting the wake signal Swk as an LF band radio signal, the first communication area 41 can be set to a size that is favorable in terms of security and convenience. For example, when the wake signal Swk is transmitted as a radio signal in a high frequency band (for example, UHF band), the first communication area 41 is wider than in the LF band. For this reason, although there is a concern that the outside verification between the electronic key 10 and the vehicle 2 is established at a position excessively away from the vehicle 2 and the vehicle door is unlocked, in this example, the wake signal Swk is set to LF. This is not the case because it is a band radio signal. Further, when the user arrives at the vehicle 2, since the outside vehicle verification is established, the user is not waited until the verification is established.

  Furthermore, the transmission timing signal Sti, the vehicle ID signal Svi, the challenge signal Scc, and the response signal Sre, which have a larger amount of information than the wake signal Swk, are transmitted as radio signals in the UHF band. Here, a larger amount of information can be transmitted more rapidly as the signal frequency is higher. Therefore, transmission of the various signals Sti, Svi, Scc, Sre can be made quicker, and thus communication between the electronic key 10 and the vehicle 2 can be performed more quickly.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) The communicable area is limited from the first communication area 41 to the second communication area 42 in a manner that includes the position of the electronic key 10 determined by the signal arrival direction of the response signal (accurately, the ACK signal Sac). . Therefore, when radio waves are relayed by the repeater 101, the receiving antenna 102 and the transmitting antenna 107 need to be installed in the second communication area 42, but the antennas 102 and 107 come close to each other. For this reason, jamming radio waves are generated in the repeater 101. On the other hand, when the receiving antenna 102 and the transmitting antenna 107 are provided at positions separated from each other, for example, the receiving antenna 102 is detached from the second communication area 42, and a request signal (more precisely, transmitted to the second communication area 42). , Vehicle ID signal Svi, challenge signal Scc), etc. cannot be received. Thereby, unauthorized communication between the vehicle 2 and the electronic key 10 via the relay device 101 can be suppressed, and the security of the electronic key system 1 can be further improved.

  (2) The position of the electronic key 10 is determined through detection of the arrival direction of the response signal. Therefore, when the communication area is limited to the second communication area 42, the second communication area 42 may be set based on the arrival direction. As a result, the second communication area 42 can be set to a narrower area while including the position of the electronic key 10, and radio wave relay by the relay 101 can be more reliably suppressed.

  (3) The transmission timing signal Sti is transmitted from the in-vehicle device 20 to the electronic key 10. The transmission timing signal Sti includes transmission timing information of various signals Svi, Sac, Scc, Sre. With the transmission timing signal Sti, the transmission timing of the various signals Svi, Sac, Scc, and Sre can be varied for each communication. Thereby, even if it is a case where a communication timing is analyzed, the unauthorized communication between the vehicle 2 and the electronic key 10 via the relay machine 101 can be suppressed.

(Second Embodiment)
A second embodiment that embodies an electronic key system according to the present invention will be described below with reference to FIG. The electronic key system of this embodiment is different from the first embodiment in that a pair of UHF transmission / reception units are provided. Hereinafter, a description will be given focusing on differences from the first embodiment. Note that the electronic key system of this embodiment has substantially the same configuration as the electronic key system of the first embodiment shown in FIG.

  As shown in FIG. 5, a pair of UHF transmission / reception units 28a and 28b are provided in the vehicle longitudinal direction. In this example, the UHF transmission / reception units 28a and 28b to which signals are transmitted are switched at a predetermined communication timing. Specifically, the transmission timing signal Sti and the vehicle ID signal Svi are transmitted by the UHF transmission / reception unit 28a, and the challenge signal Scc is transmitted by the UHF transmission / reception unit 28b.

  Incidentally, the configuration in the first embodiment has the following problems. Specifically, for example, in the repeater 101 shown in FIG. 4, the receiving antenna 102 and the transmitting antenna 107 are provided with directivity. That is, the transmission antenna 107 transmits a signal only to the UHF transmission / reception unit 28 side, and the reception antenna 102 receives only a signal from the UHF transmission / reception unit 28 side. For example, as shown by the circled numeral 3 in FIG. 4, the reception antenna 102 is not received by the transmission antenna 107 by installing the reception antenna 102 on the arrow 51 in the second communication area 42. , No disturbing radio waves are generated. Therefore, there is a possibility that radio wave relay is performed via the repeater 101.

  In this regard, in the present embodiment, as shown in FIG. 5, the UHF transmission / reception units 28a and 28b that transmit request signals are switched. That is, two second communication areas 42a and 42b are formed by request signals transmitted from both UHF transmission / reception units 28a and 28b. Specifically, the in-vehicle controller 21 calculates the signal arrival direction of the ACK signal Sac from the transmitting antenna 107 according to the wake signal Swk received by the in-vehicle receivers 24 of both UHF transmission / reception units 28a and 28b. The second communication areas 42a and 42b are set based on the received signal arrival directions. In this case, the transmission antenna 107 and the reception antenna 102 are included in the second communication area 42a formed by the UHF transmission / reception unit 28a, but the reception antenna 102 is included in the second communication area 42b formed by the UHF transmission / reception unit 28b. It will not be. This is because the second communication area 42b is formed with reference to the transmission antenna 107 to which the ACK signal Sac is transmitted.

  As a result, the receiving antenna 102 can receive the transmission timing signal Sti and the vehicle ID signal Svi transmitted from the UHF transmission / reception unit 28a and relay the radio wave to the electronic key 10 side, but transmits from the UHF transmission / reception unit 28b. Challenge signal Scc cannot be received. Therefore, radio wave relay between the vehicle 2 and the electronic key 10 by the relay 101 is prevented.

As mentioned above, according to embodiment described, in addition to the effect of (1)-(3) of 1st Embodiment, there can exist the following effects.
(4) Since the pair of UHF transmission / reception units 28a and 28b are provided, in the repeater 101, in the repeater 101, the reception signal 102 having directivity is received from the plurality of UHF transmission / reception units 28a and 28b. Cannot be received. Therefore, unauthorized communication between the vehicle 2 and the electronic key 10 via the relay device 101 can be suppressed. Thereby, the security of the electronic key system 1 can be further improved.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the above embodiment, the in-vehicle control unit 21 encrypts the transmission timing signal Sti using the encryption key and then transmits the transmission timing signal Sti. However, a random number code may be included in the transmission timing signal Sti in order to further improve security. In this case, as the random number code changes for each transmission, the transmission timing signal Sti that is encrypted including the random number code also changes. Therefore, the confidentiality of the transmission timing pattern included in the transmission timing signal Sti can be improved.

  In both the above embodiments, the so-called common key method is adopted in which the encryption key used for encryption and decryption of the transmission timing signal Sti is a common key. However, as long as the transmission timing signal Sti can be encrypted and decrypted, not only the common key method but also the public key method may be used.

  In both the above embodiments, the times T1 to T4 are determined as the transmission timings of the various signals Svi, Scc, Sac, Sre based on the transmission timing pattern stored in the memory 21a. In other words, the transmission start timing of the various signals Svi, Scc, Sac, and Sre is determined by determining the times T1 to T4. However, the transmission timing is not limited to the transmission start timing, and may be the transmission time of various signals Svi, Scc, Sac, Sre.

  In both the above embodiments, the transmission timing signal Sti includes information of each time T1 to T4 as the transmission timing of various signals. However, since the transmission timing signal Sti is a signal transmitted to the electronic key 10, only the information of the time T3 and the time T4 indicating the timing at which the electronic key 10 returns the ACK signal Sac and the response signal Sre is transmitted to the transmission timing signal Sti. You may add and transmit. In this case, since it is not necessary to add the information of time T1 and time T2 to the transmission timing signal Sti, the processing can be omitted.

  In both the above embodiments, the transmission timing signal Sti is transmitted after the transmission of the wake signal Swk and before the transmission of the vehicle ID signal Svi. However, the transmission timing of the transmission timing signal Sti is not limited to this. For example, the transmission timing of the challenge signal Scc and the response signal Sre may be changed for each communication after transmission of the vehicle ID signal Svi but before transmission of the challenge signal Scc. Further, the transmission timing signal Sti may be transmitted simultaneously with the wake signal Swk, in other words, the transmission timing information included in the transmission timing signal Sti may be added to the wake signal Swk. In this case, the transmission timing information included in the wake signal Swk becomes different information every time the wake signal Swk is transmitted.

  In both the above embodiments, the in-vehicle device 20 transmits the transmission timing signal Sti to the electronic key 10, but conversely, the electronic key 10 may transmit the transmission timing signal Sti to the in-vehicle device 20. In this case, the transmission timing pattern is stored in the memory 11 a of the electronic key control unit 11. For example, the electronic key 10 transmits the encrypted transmission timing signal Sti after returning the ACK signal Sac according to the wake signal Swk. Also in this case, the transmission timing signal Sti allows the electronic key 10 and the vehicle to commonly recognize which transmission timing pattern is used for communication, so the transmission timing pattern can be selected randomly on the electronic key 10 side. .

  In both the above embodiments, the transmission timing signal Sti including the transmission timing information is transmitted from the in-vehicle device 20 to the electronic key 10, but the transmission of the transmission timing signal Sti may be omitted. Even in this case, by limiting the transmission area of the request signal from the first communication area 41 to the second communication area 42, it is possible to prevent radio relay by the repeater 101.

  In both the above embodiments, the radio relay by the repeater 101 is prevented by changing the transmission timing of the vehicle ID signal Svi, the challenge signal Scc, the ACK signal Sac, and the response signal Sre for each communication. However, the radio wave relay can be prevented only by changing the transmission timing of any one type, for example, the vehicle ID signal Svi. In this case, it is only necessary to change the time T1 from the completion of transmission of the transmission timing signal Sti to the vehicle ID signal Svi transmission, and there is no need to change the transmission timing of the challenge signal Scc, the ACK signal Sac, and the response signal Sre. Therefore, the process concerning it can be omitted.

  In the second embodiment, a pair of UHF transmission / reception units 28a and 28b are provided. However, the number of UHF transmission / reception units 28 is not limited to a pair as long as it is plural, and may be provided, for example, three. By increasing the number of UHF transmission / reception units 28, radio wave relay by the relay 101 can be prevented more reliably.

  In the second embodiment, the transmission timing signal Sti and the vehicle ID signal Svi are transmitted by the UHF transmission / reception unit 28a, and the challenge signal Scc is transmitted by the UHF transmission / reception unit 28b, but are transmitted from the UHF transmission / reception units 28a and 28b. If the signal to be switched is switched, the type of the signal is not limited. For example, the transmission timing signal Sti may be transmitted by the UHF transmission / reception unit 28a, and the vehicle ID signal Svi and the challenge signal Scc may be transmitted by the UHF transmission / reception unit 28b.

  In both the above embodiments, the wake signal Swk is transmitted as a radio signal in the LF band, but the wake signal Swk may be transmitted as a radio signal in the UHF band. In this case, the LF transmitter 22 and the LF receiver 14 shown in FIG. 1 can be omitted. Specifically, as shown in FIG. 6, a circular first communication area 41 is formed around the vehicle 2 around the UHF transmission / reception unit 28. When the electronic key 10 enters the first communication area 41, the second communication area 42 is set based on the signal arrival direction of the ACK signal Sac from the electronic key 10 corresponding to the wake signal Swk. Even in this case, the relay 101 can prevent the radio wave relay between the vehicle 2 and the electronic key 10. Furthermore, the frequency band of various signals is not limited to the UHF band as long as it is the same frequency band that causes the repeater 101 to generate jamming radio waves.

  In both the above embodiments, the wake signal Swk is transmitted to the first communication area 41, and the vehicle ID signal Svi and the challenge signal Scc are transmitted to the second communication area 42. However, the signals transmitted to both communication areas 41 and 42 are not limited to the above combinations. For example, the wake signal Swk and the vehicle ID signal Svi are transmitted to the first communication area 41, and the challenge signal Scc is transmitted to the second communication area 42. You may send it. In this case, the in-vehicle device 20 can calculate the signal arrival direction of the vehicle ID signal Svi and form the second communication area 42 based on the signal arrival direction. Further, by calculating the arrival directions of both the wake signal Swk and the vehicle ID signal Svi, the second communication area 42 including the electronic key 10 can be formed more reliably. In addition, after transmitting the wake signal Swk to the first communication area 41, this time, the wake signal Swk is transmitted to the second communication area 42, and the ACK signal is transmitted according to the both wake signals Swk transmitted to both the communication areas 41 and 42. If there is a reply of Sac, communication may be performed thereafter, assuming that the radio relay is not performed by the repeater 101.

  In both the above embodiments, the position of the electronic key 10 outside the vehicle is determined based on the signal arrival direction of the ACK signal Sac calculated through the receiving antenna 24a which is an adaptive array antenna. However, the key position determining means for determining the position of the electronic key 10 is not limited to this, and for example, the following means may be used. That is, as indicated by an arrow 60 in FIG. 6, a circular first communication area 41 is formed by rotating a search area 45 formed in the same range as the second communication area 42 around the UHF transmission / reception unit 28. Form. Then, it may be determined that the electronic key 10 exists in the first communication area 41 when the search area 45 is rotated in the circumferential direction and the ACK signal Sac is returned. Also in this case, the communication area is limited from the first communication area 41 to the second communication area 42 formed by rotating the search area 45.

Next, the technical idea that can be grasped from the embodiment will be described together with the effects.
(A) In the electronic key system according to any one of claims 1 to 3, the first request signal is a wake signal for activating the electronic key, and the wake signal is a radio signal in a low frequency band. An electronic key system that is transmitted as a signal, and wherein the second request signal and the response signal are transmitted as radio signals in a high frequency band.

  The wake signal that is the first request signal is a signal that activates the electronic key. However, it is not preferable in terms of security that the signal reaches a position that is excessively away from the vehicle. In that respect, according to the above configuration, the wake signal is a low-frequency band radio signal, and thus is transmitted to an area of an appropriate size for security. On the other hand, communication between the vehicle and the electronic key is desired to be completed more quickly. In that respect, according to the above configuration, since the second request signal and the response signal are transmitted as radio signals in a high frequency band, a large amount of information can be transmitted quickly and communication can be performed more quickly. Can do.

  (B) In the electronic key system according to claim 3, the first request signal is a wake signal for activating the electronic key, and the response signal is an ACK signal returned in response to the wake signal. The vehicle-mounted device performs authentication communication as to whether or not the electronic key is authentic with the electronic key after confirming reception of the ACK signal through transmission / reception of the second request signal and the response signal. The transmission timing signal is transmitted after the ACK signal is transmitted.

  According to this configuration, the transmission timing signal is transmitted before authentication communication as to whether the electronic key is valid. Accordingly, the transmission timing of the second request signal and response signal transmitted and received in highly confidential authentication communication can be changed for each communication. Therefore, while ensuring the security of the electronic key system, it is not necessary to change the transmission timing of the wake signal that is the first request signal and the ACK signal corresponding to the first request signal.

(C) The electronic key system according to claim 3 or (b), wherein the transmission timing signal is an encrypted signal.
According to this configuration, since the transmission timing signal is encrypted, the secrecy can be improved. Therefore, it becomes difficult to perform illegal analysis of the transmission timing signal, and the security of the electronic key system can be further improved.

  DESCRIPTION OF SYMBOLS 1 ... Electronic key system, 2 ... Vehicle, 10 ... Electronic key, 11 ... Electronic key control part, 11a ... Memory, 12 ... UHF receiving part, 13 ... UHF transmitting part, 14 ... LF receiving part, 20 ... In-vehicle apparatus, 21 In-vehicle control unit, 21a ... Memory, 22 ... LF transmission unit, 23 ... UHF transmission unit, 24 ... In-vehicle reception unit, 28 ... UHF transmission / reception unit, 101 ... Repeater.

Claims (4)

An electronic key that is carried by the user and transmits a response signal in the same frequency band as at least one of the two request signals in response to the first request signal and the second request signal from the vehicle side;
The first request signal is transmitted to a first communication area set inside and outside the vehicle to check whether or not the electronic key is installed inside and outside the vehicle interior. When the response signal with respect to one request signal is detected, the second request signal is transmitted within a second communication area set narrower than the first communication area, and the two request signals are When it is determined that the response signals are appropriate, the vehicle-mounted device that can unlock the vehicle door and start the vehicle engine,
Key position determining means provided on the vehicle for determining the position of the electronic key relative to the vehicle based on a response signal to the first request signal;
The on-vehicle device is an electronic key system that sets the second communication area including the determined position of the electronic key based on the determination result of the key position determining means. The electronic key system according to claim 1.
The key position determination means determines the position of the electronic key through detection of the arrival direction of the response signal with respect to the first request signal,
The on-vehicle device forms the second communication area along the arrival direction, and transmits the second request signal to the same area. The electronic key system according to claim 1 or 2,
A transmission timing signal including transmission timing information of the response signal from the vehicle-mounted device to the electronic key, and a transmission timing signal including transmission timing information of at least one of the request signals from the electronic key to the vehicle-mounted device. Is sent,
The electronic key or the in-vehicle device that has received the transmission timing signal transmits different transmission timings for each communication based on at least one of the response signal and the request signals included in the transmission timing signal. An electronic key system that transmits at least one of the response signal and the two request signals. The electronic key system according to any one of claims 1 to 3,
While transmitting both the request signals based on a command from the in-vehicle device, comprising a plurality of transmission antennas arranged in the vehicle,
The key position determining means determines the position of the electronic key with respect to each transmission antenna,
The in-vehicle device forms the second communication area including the position of the electronic key determined through the response signal with respect to the first request signal transmitted from each transmission antenna, and with the electronic key. An electronic key system that switches between the transmitting antennas that transmit the two request signals during communication.

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