JP2011025714A - Electronic key system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve security by making camouflage of a position at which an electronic key exists using a wireless technique, difficult in an electronic key system. <P>SOLUTION: A vehicle-mounted device 20 determines validity of a movement of a user carrying an electronic key 10 based on aspects of variation of signal strengths of request signals Sro, Sri detected by an RSSI detection circuit 16. When it is determined that the movement of the user is not valid, it is determined as unclear whether a proper user is actually near a vehicle 2 or not, and unlock of a vehicle door or start of an engine is not allowed. In this manner, in addition to collation of ID codes, by authenticating whether the movement of the user (electronic key 10) is proper or not, camouflage of a position at which the electronic key 10 exists, is made difficult, to improve security of the electronic key system 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic key system.

  In the conventional electronic key system, when the verification of the ID code is established through transmission / reception of various signals including the electronic key (portable device) and the ID code (identification code) between the vehicles, the locking and unlocking of the vehicle door lock, the engine starting, etc. It becomes possible. 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 collation of the ID code is established through communication between the electronic key existing in the outside communication area and the vehicle, control for switching the lock state of the door lock is performed. On the other hand, when the ID code verification is established through communication between the electronic key existing in the in-vehicle communication area and the vehicle, engine start is permitted.

JP 2006-118886 A

  Due to 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. For example, it is conceivable to use a wireless communication technique to disguise an electronic key that exists far away as if it exists in a communication area inside or outside the vehicle interior. In this case, there is a concern that control on the vehicle side such as unlocking the door lock or permission to start the engine may be executed illegally. The importance of crime prevention measures against new fraud techniques such as electronic key disguise is increasing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to make it more difficult to impersonate a position where an electronic key is present using wireless technology, thereby further improving security. Is to provide.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 is mounted on a vehicle and an electronic key that transmits a response signal that is also a wireless signal that is carried by the user and that includes its own identification code in response to a request signal that is a wireless signal from the vehicle side. And a vehicle-mounted device that transmits the request signal to the interior and exterior of the vehicle and receives the response signal. When the verification of the identification code included in the response signal is established in the vehicle-mounted device, In the electronic key system that permits the start of the lock or the engine, the in-vehicle device or the electronic key includes signal strength detection means for detecting the signal strength of the radio signal transmitted and received between them, Only when the validity of the movement of the user carrying the electronic key is confirmed based on the change in the signal strength of the wireless signal detected by the signal strength detection means, And as its gist to permit the start of unlocking or engine.

  According to this configuration, the in-vehicle device determines the appropriateness of the movement of the user carrying the electronic key based on the manner of change in the signal strength of the radio signal detected by the signal strength detection means. Here, the signal strength of the radio signal has a property that it becomes stronger as the electronic key approaches the vehicle-mounted device, and becomes weaker as it moves away. For this reason, for example, when a user carrying the electronic key gets into the vehicle, the electronic key approaches the vehicle from the outside of the vehicle, and thus the signal strength is increased. Further, when the user carrying the electronic key stops, the electronic key keeps a certain distance from the vehicle, so that the signal strength is constant. The in-vehicle device determines the validity of the user's movement through the user's movement and stillness determined based on such a change in signal intensity. If it is determined that the user's movement is not appropriate, it is not known whether or not the legitimate user is actually in the vicinity of the vehicle, and unlocking of the vehicle door or starting of the engine is not permitted. In this way, in addition to the verification of the identification code through wireless communication, it is difficult to impersonate the position where the electronic key exists by authenticating whether the movement of the user (electronic key) is appropriate. Security can be improved.

  According to a second aspect of the present invention, in the electronic key system according to the first aspect, the in-vehicle device is connected between the in-vehicle device and the electronic key based on a change in the signal strength of the wireless signal detected by the signal strength detecting means. At the start of communication via the wireless signal in the vehicle until the door handle operation of the vehicle door is determined whether there is any movement to the inside of the vehicle from the start of the communication until before the door handle operation of the vehicle door The gist is that the signal strength of the signal is increased as a condition for unlocking the door or permitting engine start.

  According to this configuration, the signal strength detection means detects the approach and separation of the user from the vehicle in a state where the vehicle door is locked. Specifically, if the signal strength of the radio signal increases during the period from the start of communication between the in-vehicle device and the electronic key to before the door handle operation of the vehicle door, it is determined that there is movement toward the inside of the vehicle. . Further, if the signal strength of the radio signal does not increase during the period, that is, decreases or is a constant value, it is determined that there is no movement toward the inside of the vehicle. When there is a movement toward the inside of the vehicle during the above period, the unlocking of the vehicle door or the engine start is permitted because the user's movement is appropriate. On the other hand, if there is no movement toward the inside of the vehicle during the above period, the unlocking of the vehicle door or the engine start is not permitted because the user's movement is not appropriate. In this way, in addition to the verification of the identification code through wireless communication, whether the movement of the user (electronic key) is appropriate in the period from the start of communication between the in-vehicle device and the electronic key to before the door handle operation of the vehicle door By performing authentication, it becomes difficult to disguise the position where the electronic key exists, and the security of the electronic key system can be improved.

  According to a third aspect of the present invention, in the electronic key system according to the first or second aspect, the in-vehicle device includes an out-of-vehicle transmission device that transmits a request signal to the outside of the vehicle provided outside the vehicle, and the signal strength detection unit. Is provided in the electronic key so as to be able to detect the signal strength of a request signal from the vehicle side, and the signal strength of the request signal transmitted to the outside of the vehicle received by the electronic key is that the vehicle door is opened. The gist of the invention is that the condition for permission to start the engine is that the time is reduced from the time until the time when the user carrying the electronic key gets into the vehicle.

  According to this configuration, the signal strength detection means provided in the electronic key detects the signal strength of the request signal from the vehicle side. Here, the outside transmission device that transmits the request signal to the outside of the vehicle is provided on the outside of the vehicle, and the distance between the outside transmission device and the user (electronic key) in accordance with the entry operation of the user carrying the electronic key into the vehicle. Will leave. For this reason, during the period when the user opens and closes the vehicle door and gets into the vehicle, the signal strength of the request signal transmitted outside the vehicle received by the electronic key decreases. When the signal strength does not decrease during the above period, the in-vehicle device determines that the user does not get in, that is, the user's movement is not appropriate, and does not allow the engine to start. In this way, in addition to the verification of the identification code through wireless communication, authentication of whether the movement of the user (electronic key) at the time of getting into the vehicle is appropriate makes it possible to impersonate the position where the electronic key exists. It becomes difficult and the security of the electronic key system can be 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, the in-vehicle device includes an in-car transmission device that transmits a request signal to the inside of the car provided in the car, and the signal The strength detection means is provided in the electronic key so as to be able to detect the signal strength of the request signal from the vehicle side, and the in-vehicle device has a signal strength of the request signal transmitted into the vehicle that is received by the electronic key. The gist of the invention is that the condition for permitting engine start is an increase in the period from the opening time to the time when the user carrying the electronic key gets into the vehicle.

  According to this configuration, the signal strength detection means provided in the electronic key detects the signal strength of the request signal from the vehicle side. Here, the in-vehicle transmission device that transmits a request signal to the inside of the vehicle is provided in the vehicle, and the distance between the in-vehicle transmission device and the user (electronic key) is as the user carries the electronic key into the vehicle. Approaching. For this reason, during the period when the user opens the vehicle door and gets into the vehicle, the signal strength of the request signal received by the electronic key increases. When the signal strength does not increase during the above period, the in-vehicle device determines that the user does not get in, that is, the user's movement is not appropriate, and does not allow the engine to start. In this way, in addition to the verification of the identification code through wireless communication, authentication of whether the movement of the user (electronic key) at the time of getting into the vehicle is appropriate makes it possible to impersonate the position where the electronic key exists. It becomes difficult and the security of the electronic key system can be improved.

  Invention of Claim 5 is an electronic key system as described in any one of Claims 1-4. WHEREIN: The engine switch which starts an engine through switch operation in an engine start permission state is provided, The said vehicle equipment is The gist of the invention is that the signal strength detected by the signal strength detection means of the radio signal varies before and after the time when the engine switch is operated as a condition for permitting engine start. .

  When the user carrying the electronic key operates the engine switch, the upper body is moved or the arm is extended to operate the engine switch. Even after the engine switch is operated, the posture is returned to the original position. According to the above configuration, the validity of the user's movement is determined depending on whether or not the signal intensity varies according to the movement accompanying the user's operation of the engine switch at least before and after the time when the engine switch is operated. Judgment is being made. If the signal strength does not vary before and after the above time, the in-vehicle device determines that the user's movement is not appropriate and does not allow the engine to start. In this way, in addition to the verification of the identification code through wireless communication, it is difficult to impersonate the position where the electronic key exists by authenticating whether the movement of the user (electronic key) at the time of operating the engine switch is appropriate. The security of the electronic key system can be improved.

  According to the present invention, in an electronic key system, it is possible to improve security by making it difficult to disguise a position where an electronic key exists using wireless technology.

The block diagram of the electronic key system in this embodiment. Schematic which showed the vehicle interior / exterior antenna provided in the vehicle in this embodiment, and the vehicle interior / exterior communication area which they form. The graph which showed transition of RSSI of both request signals between each time in this embodiment. The graph which showed the calculation method of transition of RSSI in this embodiment. The flowchart which shows the process sequence of the engine starting control program in this embodiment. The graph which showed transition of RSSI of a request signal between predetermined time in other embodiments.

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. Mutual communication is automatically performed between the electronic key 10 and the in-vehicle device 20, and locking / unlocking of the vehicle door and starting of the engine are controlled on the condition that the mutual communication is established outside and inside the vehicle.

<Electronic key 10>
The electronic key 10 has a wireless communication function, and controls the in-vehicle device 20 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 an LF reception unit that is electrically connected to the electronic key control unit 11 and receives an LF band radio signal. 12 and a UHF transmitter 13 for transmitting a radio signal in the UHF band.

  When the LF receiving unit 12 receives a request signal that is an LF band radio signal transmitted from the in-vehicle device 20, the LF receiving unit 12 demodulates the request signal into a pulse signal and outputs the demodulated demodulated signal to the electronic key control unit 11. .

  The LF receiving unit 12 includes an RSSI detection circuit 16. The RSSI detection circuit 16 detects the received signal strength RSSI (Receive Signal Strength Indication) of the request signal, and performs electronic key control on the RSSI information as the detection result. To the unit 11.

  The electronic key control unit 11 is provided with a nonvolatile memory 11a made of, for example, an EEPROM or the like, and an ID code unique to the electronic key 10 is registered in the memory 11a. When the demodulated signal of the request signal is input from the LF receiver 12, the electronic key controller 11 reads the received data and generates a response signal. The ID code registered in the memory 11a and the RSSI information are added to the response signal. Then, the electronic key control unit 11 outputs a response signal including the ID code and RSSI information to the UHF transmission unit 13. Then, the UHF transmitter 13 modulates the response signal into a UHF band signal and transmits it to the in-vehicle device 20.

<In-vehicle device 20>
The in-vehicle device 20 includes a computer unit including a CPU, a ROM, a RAM, and the like. The in-vehicle device 20 includes an in-vehicle control unit 21 that controls various in-vehicle devices, an in-vehicle transmission unit 22 that is electrically connected to the in-vehicle control unit 21, an in-vehicle transmission unit 23, and an in-vehicle reception unit 24.

  When the vehicle exterior request signal Sro is input from the vehicle-mounted control unit 21, the vehicle exterior transmission unit 22 modulates the vehicle exterior request signal Sro into a radio signal having a predetermined frequency (LF band) and transmits the vehicle outside the vehicle at a preset intermittent cycle. It transmits to the periphery (outside the vehicle) of the vehicle 2 via the antenna 22a. Specifically, as shown in an enlarged circle in FIG. 2, the outside transmission antenna 22a is built in the outside door handle 4 of each vehicle door 5, and the bottom centered on the outside transmission antenna 22a is the vehicle. A vehicle exterior request signal Sro is transmitted to a semicircular vehicle exterior communication area 30 along the side. The vehicle outside transmission unit 22 and the vehicle outside transmission antenna 22a correspond to a vehicle outside transmission device.

  When the in-vehicle request signal Sri is input from the in-vehicle control unit 21, the in-vehicle transmission unit 23 modulates the in-vehicle request signal Sri into a radio signal having a predetermined frequency (LF band), and transmits the in-vehicle transmission with a preset intermittent cycle. It transmits to the room | chamber interior (vehicle interior) of the vehicle 2 via the antenna 23a. The in-vehicle transmission unit 23 and the in-vehicle transmission antenna 23a correspond to an in-vehicle transmission device.

  As shown in FIG. 2, the in-vehicle transmission antenna 23a is specifically disposed in the center of the front and rear seats (not shown), and is formed in a circular in-vehicle communication area 31 centering on both the in-vehicle transmission antennas 23a. An in-vehicle request signal Sri is transmitted. The in-vehicle communication area 31 is set so as to cover substantially the entire interior of the room by the both in-vehicle communication areas 31.

  The in-vehicle receiving unit 24 receives a response signal transmitted from the electronic key 10. Then, the response signal is demodulated into a pulse signal and output to the in-vehicle control unit 21. 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, an engine start control program to be described later, and the user's movement Various information such as a standard transition that is a criterion for determining the validity of the data is stored. The in-vehicle control unit 21 intermittently outputs the in-vehicle request signal Sro to the out-of-vehicle transmission unit 22 and the in-vehicle request signal Sri to the in-vehicle transmission unit 23 at different timings. At this time, the in-vehicle controller 21 determines whether the electronic key 10 exists outside the vehicle or inside the vehicle based on whether the received response signal is a response to the outside request signal Sro or the inside request signal Sri. Judging.

  When the response signal transmitted from the electronic key 10 in response to the request signals Sri and Sro is received by the vehicle-mounted receiving unit 24, the in-vehicle control unit 21 records the ID code included in the response signal and the memory 21a. The ID code is collated. When the verification of the ID code is established, the in-vehicle control unit 21 recognizes the RSSI information included in the response signal. The vehicle-mounted control unit 21 determines the user's movement based on the RSSI information, and permits the unlocking of the vehicle door and the engine start when the validity of the user's movement during a predetermined time (between times) is recognized. The determination of the validity of the user's movement will be described in detail later.

  As shown in FIG. 1, the in-vehicle controller 21 includes a door handle sensor 32, an engine switch 33, a door lock device 34, an engine control device 35, a seating sensor 36, and a courtesy switch 37. Connected.

  The door handle sensor 32 is provided on the outside door handle 4 as shown enlarged in the circle of FIG. The door handle sensor 32 detects the contact of the user with the outside door handle 4 and outputs the contact to the in-vehicle control unit 21.

  The door lock device 34 is a device that automatically locks and unlocks the vehicle door 5 when the vehicle door 5 is closed. When the ID code collation with the electronic key 10 outside the vehicle is established, the door lock device 34 receives the unlock signal from the in-vehicle control unit 21 and makes the vehicle door 5 unlockable. When the user touches the outside door handle 4 in this unlockable state, the door handle sensor 32 detects it and outputs the detection result to the in-vehicle control unit 21. Thereby, the vehicle-mounted control part 21 unlocks the vehicle door 5 through the door lock apparatus 34, after confirming the validity of the user's movement mentioned later.

  The engine control device 35 is connected to a cell motor (not shown). And when the validity of the user's movement mentioned later is confirmed, a drive signal is input from the vehicle-mounted control part 21, and it will be in an engine starting permission state. In this engine start permission state, when the engine switch 33 installed near the driver's seat is operated, the in-vehicle control unit 21 drives the cell motor of the engine control device 35 to start the engine. Further, the engine control device 35 outputs an engine state signal indicating the driving state of the engine to the in-vehicle control unit 21.

  The seating sensor 36 is embedded in the driver's seat, detects the user's seating, and outputs it to the in-vehicle control unit 21. The courtesy switch 37 is provided on the side surface of the vehicle door 5 and detects opening and closing of the vehicle door 5. The detection result of the courtesy switch 37 is output to the in-vehicle control unit 21.

As described above, the vehicle-mounted control unit 21 determines the validity of the user's movement during a predetermined time (between times) based on the RSSI information.
In FIG. 3, from time t1 when the user enters the vehicle 2 and the vehicle door 5 is closed from the time t1 when the in-vehicle control unit 21 receives a response signal returned by the electronic key 10 entering the outside communication area 30 and returning. The transition of RSSI up to time t7 after a certain time has elapsed is shown.

  The transition of RSSI is based on the RSSI information included in the response signal from the electronic key 10 side returned every predetermined cycle according to the request signals Sri and Sro transmitted every predetermined cycle from the vehicle 2 side. It becomes possible to recognize by accumulating in the memory 21a. Specifically, as shown in FIG. 4, the RSSI for each predetermined period (every predetermined time) included in the RSSI information is plotted. The RSSI transition is obtained by drawing an approximate line for each plot.

  The direction of movement of the electronic key 10 can be determined through the RSSI transition. The RSSI is determined depending on the distance between the electronic key 10 and the outside transmission antenna 22a or the inside transmission antenna 23a. Specifically, the RSSI is large when the electronic key 10 is close to both transmission antennas 22a and 23a, and the RSSI is small when the electronic key 10 is far. Due to such properties, when the RSSI transition has a positive slope, it can be determined that the electronic key 10 is moving toward the outside transmission antenna 22a or the inside transmission antenna 23a, and when the RSSI has a negative slope, It can be determined that the electronic key 10 is moving in a direction away from the outside transmission antenna 22a or the inside transmission antenna 23a. Based on the determination of the direction of the user's movement, the validity of the user's movement described later is determined.

  Next, a processing procedure from unlocking the vehicle door 5 to starting the engine by the in-vehicle control unit 21 will be described with reference to a flowchart of FIG. The flowchart is executed according to an engine start control program stored in advance in the memory 21a of the in-vehicle control unit 21. Note that FIG. 3 and FIG. 4 are referred to for determining the appropriateness of the user's movement.

  First, in a state where the vehicle door 5 is locked, the in-vehicle control unit 21 transmits an out-of-vehicle request signal Sro to the out-of-vehicle communication area 30 via the out-of-vehicle transmission antenna 22a. When the in-vehicle device 20 receives a response signal that is returned by the electronic key 10 carried by the user entering the in-vehicle communication area 30, the in-vehicle control unit 21 performs verification (external vehicle verification) of the ID code included in the response signal. (S101). When the vehicle outside verification is established (YES in S101), the in-vehicle control unit 21 determines the validity of the user's movement, that is, the presence / absence of the movement toward the vehicle 2 (S102). On the other hand, when the outside vehicle verification is not established (NO in S101), the in-vehicle control unit 21 ends the engine start control program without permitting the unlocking of the vehicle door 5.

  As shown in FIG. 3, the determination of the presence or absence of movement of the user toward the vehicle 2 is performed from time t1 when the response signal is received to time t2 when contact with the user's outside door handle 4 is detected by the door handle sensor 32. Based on the transition of RSSI. In the period up to time t2, only the vehicle exterior request signal Sro is transmitted, and the vehicle interior request signal Sri is not transmitted.

  From time t1 to time t2, the user carrying the electronic key 10 approaches the driver's side vehicle door 5 (exactly, the driver's side outside transmission antenna 22a) from the outside of the vehicle. For this reason, as shown in the upper part of FIG. 3, it is assumed that the RSSI of the outside request signal Sro gradually increases, and the slope of the RSSI transition is positive. That is, when the slope of the RSSI transition is positive, the in-vehicle control unit 21 determines that the user has moved toward the vehicle 2 (YES in S102), and the vehicle door 5 via the door lock device 34. Is unlocked (S103).

  If the slope of the RSSI transition is not positive and less than or equal to zero, the in-vehicle control unit 21 determines that the user does not move toward the vehicle 2 (NO in S102), and does not unlock the vehicle door 5. Finally, the engine start control program is terminated. Thereby, in the position away from the vehicle 2, it is possible to prevent unauthorized outside collation due to radio wave interception of the electronic key 10 held by the stationary user, and consequently unlocking the vehicle door 5.

  When the vehicle door 5 is normally unlocked, the user closes the vehicle door 5 after opening the vehicle door 5 through the operation of the outside door handle 4 and sitting on the driver's seat. At this time, the in-vehicle controller 21 can detect the opening / closing of the vehicle door 5 through the courtesy switch 37. The seating sensor 36 detects the user's seating on the driver's seat. As shown in FIG. 3, the in-vehicle controller 21 recognizes the time t3 when the vehicle door 5 is opened and the time t5 when the user is seated in the driver's seat based on the detection results of the courtesy switch 37 and the seating sensor 36. Here, the vehicle-mounted control unit 21 recognizes the time t3 when the vehicle door 5 is opened through the detection result of the courtesy switch 37. From time t2 when the vehicle touches the outside door handle 4 to time t3 when the vehicle door 5 is opened, the user operates the outside door handle 4 outside the vehicle, and there is no change in the transition of RSSI. In the present embodiment, the validity of the user's movement is not determined for the RSSI transition from time t2 to time t3.

  When the in-vehicle control unit 21 recognizes that the vehicle door 5 is opened, the in-vehicle request signal Sri is transmitted in addition to the out-vehicle request signal Sro. And the vehicle-mounted control part 21 stops transmission of the request signal Sro outside a vehicle, when seating is detected. That is, the in-vehicle controller 21 transmits the in-vehicle request signal Sri in addition to the out-of-vehicle request signal Sro from time t3 to time t5, and the request signals Sri and Sro are transmitted to both communication areas 30 and 31.

  Here, when the vehicle door 5 is opened, the in-vehicle request signal Sri transmitted to the in-vehicle communication area 31 slightly leaks outside the vehicle. For this reason, the electronic key 10 may receive both request signals Sri and Sro at the same time, although locally. At this time, the electronic key 10 returns a response signal corresponding to the outside request signal Sro emitted from the outside transmission antenna 22a and a response signal corresponding to the inside request signal Sri emitted from the inside transmission antenna 23a. Therefore, the in-vehicle control unit 21 has the RSSI of the vehicle exterior request signal Sro emitted from the vehicle exterior transmission antenna 22a shown in the upper part of FIG. 3 and the RSSI of the vehicle interior request signal Sri emitted from the vehicle interior transmission antenna 23a shown in the lower part of FIG. Both transitions are calculated during the same period.

  The user carrying the electronic key 10 moves in a direction away from the vehicle-mounted transmitting antenna 22a during a period from time t3 when the vehicle door 5 is opened to time t5 when the user enters the vehicle and sits in the driver's seat. For this reason, it is assumed that the RSSI of the outside request signal Sro gradually decreases, and the slope of the RSSI transition is negative. That is, the in-vehicle control unit 21 determines whether or not there is any movement in the direction away from the user's outside transmission antenna 22a based on the inclination of the RSSI transition (S104).

  When the slope of the RSSI transition is negative, the in-vehicle control unit 21 determines that the user's movement is appropriate, assuming that the user moves in a direction away from the vehicle-mounted transmitting antenna 22a (YES in S104). . Thereby, the first condition for setting the engine start permission state is satisfied.

  On the other hand, when the slope of the RSSI transition is not negative and is greater than or equal to zero, the in-vehicle control unit 21 determines that the user's movement is not appropriate because the user does not move in the direction away from the outside transmission antenna 22a ( NO in S104). In this case, the engine start control program is terminated without setting the engine start permission state. As a result, it is possible to prevent an illegal engine start or the like due to radio wave interception of the electronic key 10 held by the stationary user at a position away from the vehicle 2.

  Moreover, as shown in FIG. 3, the time when the vehicle-mounted device 20 receives the response signal returned by the electronic key 10 carried by the user entering the in-vehicle communication area 31 is defined as time t4. That is, the in-vehicle control unit 21 can recognize the RSSI transition of the in-vehicle request signal Sri after time t4.

  The vehicle-mounted control unit 21 performs verification (in-vehicle verification) of the ID code included in the response signal received at time t4 (S105). When the in-vehicle collation is established (YES in S105), the in-vehicle control unit 21 determines whether or not the user moves in the direction of the in-vehicle transmission antenna 23a through the RSSI transition from time t3 to time t5 (S106). On the other hand, when the in-vehicle verification is not established (NO in S105), the in-vehicle control unit 21 ends the engine start control program without setting the engine start permission state.

  It is assumed that the user carrying the electronic key 10 moves in the direction of the in-vehicle transmission antenna 23a from the time t3 when the vehicle door 5 is opened to the time t5 when the user enters the vehicle and sits in the driver's seat. Therefore, the RSSI of the in-vehicle request signal Sri is assumed to gradually increase, and the slope of the RSSI transition is positive. Therefore, when the slope of the RSSI transition is positive, the in-vehicle control unit 21 determines that the user's movement is appropriate, assuming that the user has movement toward the in-vehicle transmission antenna 23a (YES in S106). Thereby, the second condition for setting the engine start permission state is satisfied. On the other hand, when the slope of the RSSI transition is not positive and is equal to or less than zero, the in-vehicle control unit 21 determines that the user does not move in the direction of the in-vehicle transmission antenna 23a and the user's movement is not appropriate (NO in S106). ). In this case, the engine start control program is terminated without setting the engine start permission state. Thereby, in the position away from the vehicle 2, an illegal engine start or the like due to radio wave interception of the electronic key 10 possessed by the user can be prevented.

  As shown in FIG. 3, the movement of the user is indefinite from time t5 when the user is seated to time t6 when the vehicle door 5 is closed. For this reason, no judgment is made on the transition of the RSSI of the in-vehicle request signal Sri from time t5 to time t6 indicated by a two-dot chain line in the lower part of FIG.

  Further, it is assumed that the user does not move during a certain time T1 from the time t6 when the vehicle door 5 is closed to the time t7. This is because when the user performs the closing operation of the vehicle door 5, it is assumed that the user cannot move in the vehicle at the time t6 when the vehicle door 5 is closed. The fixed time T1 is set to be extremely short. For this reason, it is assumed that the RSSI of the in-vehicle request signal Sri is constant from time t6 to time t7, and the slope of the RSSI transition is zero.

  As shown in an enlarged manner in the circle of FIG. 3, the RSSI at time t6 is set as a reference value 41, and a certain allowable range 42 is set with the reference value 41 as a center value. When the RSSI changes within the allowable range 42, the gradient of the RSSI transition is determined to be zero. The permissible range 42 is set to a range including a detection error and an inclination of RSSI transition caused by a fine movement of the user by simulation or the like. The in-vehicle control unit 21 determines whether the user is stationary from time t6 to time t7 through the slope of the RSSI transition (S107).

  If it is determined that the RSSI transition slope is zero, the in-vehicle control unit 21 determines that the user's movement is appropriate, assuming that the user is stationary (YES in S107). Thus, the third condition for setting the engine start permission state is satisfied. On the other hand, when it is determined that the slope of the RSSI transition is not zero, the in-vehicle control unit 21 determines that the user's movement is not appropriate because the user is not stationary (NO in S107). In this case, the vehicle-mounted control unit 21 ends the engine start control program without setting the engine start permission state. As a result, it is possible to prevent an unauthorized engine start or the like due to radio wave interception or the like of the electronic key 10 held by a user who is not stationary at a position away from the vehicle 2.

  When the first to third conditions for setting the engine start permission state are satisfied, the in-vehicle control unit 21 sets the engine start permission state via the engine control device 35 (S108). Furthermore, the vehicle-mounted control unit 21 sends a drive signal to the engine control device 35 on condition that an operation signal is input from the engine switch 33 in a state where the depression of the brake is detected in the engine start permission state (S109). The engine is output to start the engine (S110). And the vehicle-mounted control part 21 complete | finishes an engine starting control program.

  Thus, since the unlocking of the vehicle door 5 and the starting of the engine are possible only when the validity of the user's movement is confirmed, the security of the vehicle 2 can be improved. Further, both request signals Sri and Sro used for determining the validity of the user's movement are radio signals in the LF band, and the transition of RSSI is more stable than that in the high frequency band. For this reason, it is possible to determine the movement of the user with higher accuracy.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) The on-vehicle device 20 determines the appropriateness of the movement of the user carrying the electronic key 10 based on the change in the signal strength of the request signals Sro and Sri detected by the RSSI detection circuit 16. Here, the RSSI of the request signals Sro and Sri has a property that it becomes stronger as the electronic key 10 approaches the vehicle-mounted device 20 and becomes weaker as it is separated. For this reason, for example, when the user carrying the electronic key 10 gets into the vehicle 2, the RSSI becomes strong because the electronic key 10 approaches the vehicle 2 from the outside of the vehicle. When the user carrying the electronic key 10 stops, the RSSI is constant because the electronic key 10 maintains a certain distance from the vehicle 2. The in-vehicle device 20 determines the appropriateness of the user's movement through the user's movement and stillness determined based on the RSSI change mode. When it is determined that the user's movement is not appropriate, it is not known whether or not the legitimate user is actually near the vehicle 2 and the unlocking of the vehicle door 5 or the engine start is not permitted. In this way, in addition to the ID code verification, authentication of whether the movement of the user (electronic key 10) is appropriate makes it difficult to disguise the position where the electronic key 10 exists, and the security of the electronic key system 1 Can be improved.

  (2) The RSSI detection circuit 16 detects the approach and separation of the user to the vehicle 2 in a state where the vehicle door 5 is locked. Specifically, when the RSSI of the outside request signal Sro increases during the period from the time t1 when the response signal of the electronic key 10 is received to the time t2 when the door handle 4 of the vehicle door 5 is operated, the movement toward the inside of the vehicle It is judged that there is. Further, if the RSSI of the outside request signal Sro does not increase during the above period, it is determined that there is no movement toward the inside of the vehicle. When the in-vehicle device 20 moves toward the inside of the vehicle during the above period, the unlocking of the vehicle door 5 is permitted because the user's motion is appropriate. On the other hand, if the in-vehicle device 20 does not move toward the inside of the vehicle during the above period, the unlocking of the vehicle door 5 is not permitted because the user's movement is not appropriate. Thus, in addition to the ID code verification, whether the user (electronic key 10) moves appropriately from time t1 when the response signal of the electronic key 10 is received to time t2 when the door handle 4 of the vehicle door 5 is operated is appropriate. By performing authentication, it is difficult to disguise the position where the electronic key 10 exists, and the security of the electronic key system 1 can be improved.

  (3) The RSSI detection circuit 16 provided in the electronic key 10 detects the RSSI of the request signals Sro and Sri from the vehicle 2 side. Here, the vehicle exterior transmitter 22 that transmits the vehicle exterior request signal Sro is provided on the door handle 4 on the vehicle exterior side. As the user carrying the electronic key 10 enters the vehicle, the vehicle exterior transmitter 22 and the user The distance from (electronic key 10) increases. For this reason, the RSSI of the outside request signal Sro received by the electronic key 10 decreases during the user entry operation period (time t3 to time t5) from the time t3 when the vehicle door 5 opens to the time t5 when the user is seated. When the RSSI is not decreased during the user's boarding operation period, the in-vehicle device 20 determines that the user has no boarding operation, that is, the user's movement is not appropriate, and does not allow the engine to start. As described above, it is difficult to impersonate the position where the electronic key 10 exists by authenticating whether the movement of the user (electronic key 10) is appropriate in the operation period of getting into the vehicle 2 in addition to the verification of the ID code. Thus, the security of the electronic key system 1 can be improved.

  (4) The RSSI detection circuit 16 provided in the electronic key 10 detects the RSSI of the request signals Sro and Sri from the vehicle side. Here, the in-vehicle transmission unit 23 for transmitting the in-vehicle request signal Sri is provided in the vehicle. As the user carrying the electronic key 10 gets into the vehicle, the in-vehicle transmission unit 23 and the user (electronic key 10). The distance is getting closer. For this reason, during the user's boarding operation period (from time t3 to time t5), the RSSI of the in-vehicle request signal Sri received by the electronic key 10 increases. When the RSSI does not increase during the period, the in-vehicle device 20 determines that the user does not get in, that is, the user's movement is not appropriate, and does not allow the engine to start. As described above, it is difficult to impersonate the position where the electronic key 10 exists by authenticating whether the movement of the user (electronic key 10) at the time of getting into the vehicle 2 is appropriate in addition to the verification of the ID code. Thus, the security of the electronic key system 1 can be improved.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the above embodiment, the transition of RSSI of the outside request signal Sro between time t1 and time t2, between time t3 and time t5, and the inside request signal Sri between time t3 and time t5, between time t6 and time t7 The validity of the user's movement was judged based on the transition of RSSI. In other words, as shown in the flowchart of FIG. 5, the validity of the user's movement is determined based on a total of four conditions of steps S102, S104, S106, and S107. However, the number and combination of conditions (S102, S104, S106, and S107) imposed for determining the appropriateness of the user's movement are not limited to this. For example, only whether there is a vehicle-side movement between time t1 and time t2 in step S102 may be used as a criterion for determining the validity of the user's movement. In this case, the determinations in steps S104, S106, and S107 are not performed in the engine start control program. Similarly, the validity of the user's movement may be determined only for step S102 and step S104, for example, by combining the conditions. In this case, the determination in steps S106 and S107 is not performed in the engine start control program.

  In the above embodiment, on the electronic key 10 side, RSSI information is included in the response signal and transmitted to the vehicle 2 side without making any judgment on the detection result of the RSSI detection circuit 16. However, the validity of the user's movement may be determined on the electronic key 10 side. In this case, a signal indicating that the times t1 to t7 are reached is transmitted from the vehicle 2 side to the electronic key 10, and the electronic key control unit 11 recognizes the times t1 to t7 based on the signals. And the electronic key control part 11 judges the validity of a user's movement based on transition of RSSI between each time t1-t7. The validity determination result is transmitted to the vehicle side. Thereby, since it is not necessary to judge the validity of a user's movement in the vehicle 2 side, the processing burden on the vehicle 2 side can be reduced.

  In the above embodiment, when the user does not move to the vehicle side in step S102 shown in the flowchart of FIG. 5, the engine start control program is terminated without unlocking the vehicle door 5. However, as a new condition for setting the engine start permission state in step S102, the engine start permission state may not be set when the user does not move toward the vehicle. According to this process, although the vehicle door 5 can be unlocked when the user does not move toward the vehicle in step S102, the engine start is not permitted. Unauthorized engine starting can be prevented.

  In the above embodiment, the RSSI detection circuit 16 is provided in the LF receiver 12 of the electronic key 10. However, the position where the RSSI detection circuit 16 is provided is not limited to this. For example, the electronic key control unit 11 may be provided on the electronic key 10 side. Moreover, you may provide in the vehicle equipment 20. In this case, for example, the RSSI detection circuit 16 is provided in the in-vehicle receiver 24 and detects the RSSI of the response signal. Even in this case, since the RSSI detected by the RSSI detection circuit 16 varies according to the approach and separation of the electronic key 10 from the vehicle 2, the transition of the RSSI can be calculated. Therefore, the validity of the user's movement can be determined as in the above embodiment. In this configuration, since it is not necessary to include RSSI information in the response signal, the processing load on the electronic key 10 side can be particularly reduced.

  Further, the RSSI detection circuit 16 may be provided as an RSSI detection device independently at a position other than the electronic key 10 and the in-vehicle device 20. In this case, the RSSI detection device is installed outside the vehicle 2, for example, and detects the signal strength of the request signal or the response signal between the electronic key 10 and the in-vehicle device 20. Also in this structure, RSSI according to the distance between the electronic key 10 and the vehicle-mounted device 20 is detected. The detection result of the RSSI detection device is output to the electronic key 10 or the in-vehicle device 20.

  In the above embodiment, the RSSI transition of the in-vehicle request signal Sri from time t5 to time t6 indicated by a two-dot chain line in FIG. 3 is calculated, but no judgment is made for it. Therefore, transmission of the request signal Sri may be stopped from time t5 to time t6. In this case, it is unnecessary to transmit the request signal Sri and recognize the RSSI transition from the time t5 to the time t6 while securing the effect of improving the security of the above embodiment. Can be reduced.

  In the above embodiment, the validity of the user's movement is determined based on the slope of the RSSI transition. However, the determination of the validity of the user's movement is not limited to this method. Specifically, the validity of the user's movement may be determined through comparison of RSSI at each time t1 to t7. For example, the RSSI at time t1 is compared with the RSSI at time t2, and if the RSSI at time t2 is larger than the RSSI at time t1, it is determined that the user is approaching the vehicle 2 and the user's movement is appropriate. In this case, the validity can be determined only by comparing the RSSIs at the times t1 to t7, so that the determination of the validity is further facilitated.

  The validity of the user's movement may be determined by the following method. That is, the RSSI transition corresponding to the user's movement assumed in simulation or the like is set as the reference transition. A certain allowable range is set with the reference transition as the center value. If the RSSI transition is within the allowable range, it is determined that the user's movement is appropriate. If the RSSI transition is outside the allowable range, the user's movement is determined to be inappropriate. Even with this method, the validity of the user's movement can be determined as in the above embodiment.

  In the above embodiment, the seating sensor 36 is provided to detect the user's seating on the driver's seat. However, the seating sensor 36 may be omitted. In this case, it is determined that the user is surely seated at time t6 when the vehicle door 5 detected via the courtesy switch 37 is closed, and the user's movement is based on the RSSI transition from time t3 to time t6. Specifically, it is determined whether or not the user has entered the driver's seat.

  -In the said embodiment, the 1st-3rd conditions were imposed in order to set it as an engine starting permission state. However, the conditions are not limited to these. When the user carrying the electronic key 10 operates the engine switch 33, the upper body is moved or the arm is extended to operate the engine switch 33. At this time, some movement occurs in the electronic key 10. That is, as shown in FIG. 6, in addition to the condition that the slope of the RSSI transition of the in-vehicle request signal Sri is not zero between the time t21 when the engine switch 33 is operated and the time t20 before the same time t21. Also good. In this case as well, when the allowable range B is set in the same manner as between the time t6 and the time t7, and the RSSI transition does not deviate from the allowable range B, the slope of the RSSI transition is determined to be zero. The allowable range B is set to a range including a gradient of RSSI transition caused by a fine motion that is not a detection error or a user's switch operation by simulation or the like. Even after the time t21 when the engine switch 33 is operated, for example, there is a movement associated with the switch operation such as returning the extended arm. Based on the RSSI transition from the time t20 to a certain time after the time t21, the user The validity of the movement may be judged.

  When the above conditions are added, as shown in step S150 of the two-dot chain line shown in the flowchart of FIG. 5, the in-vehicle controller 21 moves the user according to the operation of the engine switch 33 from time t20 to time t21 through the transition of RSSI. Determine the presence or absence.

  If the slope of the RSSI transition is not zero, the in-vehicle control unit 21 determines that the user's movement is appropriate, assuming that the user has movement (YES in S150). On the other hand, when the slope of the RSSI transition is zero, the in-vehicle control unit 21 determines that the user's movement is not appropriate because the user has no movement (NO in S150). In this case, the vehicle-mounted control unit 21 ends the engine start control program without setting the engine start permission state. Thus, by imposing new conditions, the security of the vehicle 2 can be further improved.

  In the above embodiment, the door handle sensor 32 is provided on the outside door handle 4, and gripping of the user's outside door handle 4 is detected by the door handle sensor 32, and the detected time is recognized as time t <b> 2. Was. However, if it is possible to detect gripping of the outside door handle 4 by the user, the present invention is not limited to the door handle sensor 32. For example, an operation switch is provided on the outside door handle 4 and the operation is performed at time t2. You may recognize it.

  In the above embodiment, the electronic key control unit 11 includes the RSSI information that is the detection result of the RSSI detection circuit 16 in the response signal and transmits the response signal to the vehicle 2 side. However, the RSSI information may be included in a new radio signal different from the response signal and transmitted to the vehicle 2 side. In this case, since it is not necessary to include an ID code in the new radio signal, it is possible to reduce processing related to ID verification of the in-vehicle control unit 21.

  In the above embodiment, the validity of the user's motion is not determined for the RSSI transition from time t2 to time t3, but the validity of the user's motion is also evaluated from time t2 to time t3. Judgment may be made. That is, from the time t2 when the vehicle touches the outside door handle 4 to the time t3 when the vehicle door 5 is opened, the user operates the outside door handle 4 outside the vehicle, but the user cannot perform other operations. Therefore, from time t2 to time t3, the RSSI is assumed to be constant, and the slope of the RSSI transition is zero. In this case, the validity of the user's motion can be more accurately determined by setting the allowable range 42 in the same way as the above-described time t6 to time t7 shown in FIG.

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 5, in the in-vehicle device, the signal strength of the wireless signal detected by the signal strength detection means is constant from the time when the vehicle door is closed. An electronic key system that requires a constant value over a period of time to permit engine start.

  When the user performs the closing operation of the vehicle door, it is assumed that the user can not perform other operations and is stationary within a certain time from the closing time of the vehicle door. According to the above configuration, the validity of the user's movement is determined based on whether or not the user is stationary, that is, whether or not the signal intensity is a constant value at a certain time from the time when the vehicle door is closed. When a signal intensity of a non-constant value is detected for a certain period of time from the above time, the in-vehicle device determines that the user's movement is not appropriate and does not allow the engine to start. In this way, in addition to the verification of the identification code through wireless communication, it is difficult to impersonate the position where the electronic key is present by authenticating whether the movement of the user (electronic key) when the vehicle door is closed is appropriate. The security of the electronic key system can be improved.

  (B) In the electronic key system according to any one of claims 3 to 5, the driver's seat is provided with a seating sensor that detects whether or not the user is seated in the driver's seat, and the in-vehicle device includes the seating device. An electronic key system in which a time at which a user is seated by a sensor is set as a time at which the user gets into the vehicle.

  According to this configuration, by providing the seating sensor in the driver's seat, it is possible to accurately detect the time when the user gets into the vehicle. For this reason, it is possible to improve the accuracy of determining the validity of the user's movement.

  (C) In the electronic key system according to any one of claims 2 to 5, the outside door handle provided on the vehicle door is provided with a handle operation detecting means for detecting an operation of the user by the handle. The vehicle-mounted device is an electronic key system in which a time before the time when the handle operation detecting means detects the operation of the handle is set before the door handle operation of the vehicle door.

  According to this configuration, by providing the outside door handle with the handle operation detection means, it is possible to accurately detect the time before the door handle operation of the vehicle door. For this reason, it is possible to improve the accuracy of determining the validity of the user's movement.

  (D) In the electronic key system according to any one of claims 3 to 5, the vehicle door is provided with a courtesy switch for detecting opening and closing of the vehicle door, and the in-vehicle device is a detection result of the courtesy switch. An electronic key system that recognizes when the vehicle door is open and closed.

  According to this configuration, the in-vehicle device can recognize the time when the vehicle door is opened and the time when the vehicle door is closed by providing the courtesy switch.

  DESCRIPTION OF SYMBOLS 1 ... Electronic key system, 2 ... Vehicle, 10 ... Electronic key, 11 ... Electronic key control part, 11a ... Memory, 12 ... LF receiving part, 13 ... UHF transmission part, 16 ... RSSI detection circuit (signal strength detection means), DESCRIPTION OF SYMBOLS 20 ... Car-mounted apparatus (car-mounted machine), 21 ... Car-mounted control part (car-mounted control apparatus), 21a ... Memory, 22 ... Out-of-vehicle transmission part, 22a ... Out-of-car transmitting antenna, 23 ... In-car transmitting part, 23a ... In-car transmitting antenna, 24 ... On-vehicle receiver, 24a ... receiving antenna, 32 ... door handle sensor (handle operation detecting means), 33 ... engine switch, 34 ... door lock device, 35 ... engine control device, 36 ... seating sensor, 37 ... courtesy switch.

Claims (5)

An electronic key that transmits a response signal that is also a radio signal including its own identification code in response to a request signal that is carried by the user and that is a radio signal from the vehicle side, and is mounted on the vehicle and transmits the request signal to the vehicle interior. An in-vehicle device that transmits the outside and receives the response signal,
In the electronic key system that permits unlocking the vehicle door or starting the engine when the verification of the identification code included in the response signal is established in the in-vehicle device,
The in-vehicle device or the electronic key includes signal strength detection means for detecting signal strength of the radio signal transmitted and received between them,
The in-vehicle device unlocks the vehicle door only when the validity of the movement of the user carrying the electronic key is confirmed based on the mode of change in the signal strength of the radio signal detected by the signal strength detection means. An electronic key system that allows the engine to start. The electronic key system according to claim 1.
The vehicle-mounted device starts from the start of communication via the wireless signal between the vehicle-mounted device and the electronic key based on the change in the signal strength of the wireless signal detected by the signal strength detection means until before the door handle operation of the vehicle door. The presence or absence of movement of the user to the inside of the vehicle is determined, and it is confirmed that the signal strength of the wireless signal has increased from the start of the communication to before the door handle operation of the vehicle door. Electronic key system as a requirement. The electronic key system according to claim 1 or 2,
The in-vehicle device includes an out-of-vehicle transmission device that transmits a request signal to the outside of the vehicle provided outside the vehicle,
The signal strength detection means is provided in the electronic key so as to be able to detect the signal strength of a request signal from the vehicle side,
The in-vehicle device has a signal strength of the request signal transmitted outside the vehicle that is received by the electronic key decreases in a period from a time when a vehicle door is opened to a time when a user carrying the electronic key gets into the vehicle. An electronic key system that makes it necessary to start the engine. The electronic key system according to any one of claims 1 to 3,
The in-vehicle device includes an in-vehicle transmission device that transmits a request signal to the inside of the vehicle provided in the vehicle,
The signal strength detection means is provided in the electronic key so as to be able to detect the signal strength of a request signal from the vehicle side,
The in-vehicle device has a signal strength of a request signal transmitted to the inside of the vehicle received by the electronic key in a period from a time when the vehicle door is opened to a time when the user carrying the electronic key gets into the vehicle. An electronic key system that makes it necessary to start the engine. In the electronic key system according to any one of claims 1 to 4,
It has an engine switch that starts the engine through switch operation in the engine start permission state,
The vehicle-mounted device has an electronic start condition that allows the signal strength detected by the signal strength detection means of the radio signal to vary at least before and after the time when the engine switch is operated. Key system.

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