JP2014092001A - Electronic key system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic key system capable of securing crime prevention even when a radio wave directed to a communication area set at a vehicle side part is propagated to a periphery of an opposite vehicle side part.SOLUTION: A reception circuit of a vehicle is provided with first and second switches 37, 38 which switch the path of a reception signal of a first receiving antenna 20 between a normal line 35 and a delay line 36. An ECU determines on which of the driver's seat side and passenger's seat side of the vehicle a portable machine is positioned based upon the large/small relation between an output value of a filter 34 when the path of the reception signal of the first receiving antenna 20 is switched to the normal line 35 and an output value of the filter 34 when the path is switched to the delay line 36. The ECU permits a door lock device to operate when the determination result coincides with a side where a response from the portable machine is originally expected and does not permit the door lock device to operate when not.

Description

  The present invention relates to an electronic key system.

  2. Description of the Related Art Conventionally, as described in Patent Document 1, for example, an electronic key system that controls a vehicle through wireless communication between a portable device carried by a user and the vehicle is well known. In this system, the ECU (electronic control unit) of the vehicle sequentially forms response areas around the doors by sequentially transmitting response requests through transmission antennas provided at the doors of the vehicle. When the ECU receives a response from the portable device in response to the response request, it collates the ID code included in the response with the ID code stored in itself, and when the collation is established, the touch sensor provided on the door handle Start up. When the operation of the door handle is detected through the touch sensor, the ECU unlocks the door.

JP 2012-0667463 A

  However, the electronic key system of Patent Document 1 has the following concerns. In other words, it is originally preferable that a prescribed communication area (electric field distribution) is formed only around the door on the side where the user who opens and closes the door exists. However, depending on the mounting position of the transmission antenna in the vehicle, a response request transmitted from each transmission antenna provided on the left and right doors may propagate to the vicinity of the door on the opposite side to the door on which the vehicle is provided.

  For example, a response request transmitted from a transmission antenna provided on the right door of the vehicle is slightly propagated around the left door. In this case, when a legitimate user (mobile device) is located near the left door without the intention of getting on, the mobile device responds to a response request from the transmission antenna of the right door. Then, collation of the ID code is established regardless of the user's intention, and the touch sensor is activated. For this reason, the third party can actually open and close the right door on the side opposite to the left door where the legitimate user exists, and thus can get on. In this regard, there is room for improvement from the viewpoint of crime prevention.

  The present invention was made in order to solve the above-mentioned problems, and the purpose thereof is a case where a radio wave directed to a communication area set on the vehicle side portion propagates around the opposite vehicle side portion, An object of the present invention is to provide an electronic key system capable of ensuring crime prevention.

  An electronic key system that solves the above problem transmits a response request to a communication area that is set at least around the side of the driver's seat side of the vehicle, and when there is a response from the portable device to the response request, An electronic key system having an in-vehicle control circuit that permits the operation of a vehicle door lock is assumed. The vehicle has first and second receiving antennas that are spaced from each other in the vehicle width direction, and the control circuit receives a response first from among the first and second receiving antennas. Based on the above, it is determined whether the portable device is located on the driver side or the passenger seat side of the vehicle, and when the determination result matches the side on which the response from the portable device is originally expected, Allow operation, and do not allow door lock operation when they do not match.

  According to this configuration, the first and second receiving antennas are separated in the vehicle width direction. For this reason, the timing at which the first and second receiving antennas receive a response differs depending on whether the portable device is located on the driver's seat side or on the passenger seat side. For example, when the first receiving antenna is provided on the passenger seat side of the vehicle and the second receiving antenna is provided on the driver seat side, the response from the portable device when the portable device is located on the driver seat side. First, the second receiving antenna receives the signal, and the first receiving antenna receives the signal after that. Conversely, when the portable device is positioned on the passenger seat side, the response from the portable device is first received by the first receiving antenna, and the second receiving antenna is received after that. In this way, it is possible to determine whether the portable device is located on the driver seat side or the passenger seat side of the vehicle based on the reception timings of the first and second receiving antennas.

  For example, assuming that a response from the driver's seat side is expected, the door lock operation is permitted when it is determined that the portable device is located on the driver's seat side. On the other hand, when it is determined that the portable device is located on the passenger seat side, the door lock operation is not permitted. In this case, it is conceivable that the response request is propagated not only to the communication area on the driver's seat side where a response from the portable device is expected, but also to the periphery on the opposite passenger seat side. Thus, crime prevention is ensured by restricting the operation of the door lock when the portable device is located on the side of the vehicle that is not expected to respond.

  More specifically, when the user (portable device) is located near the side of the passenger side of the vehicle without the intention of boarding, it is directed to a communication area set around the side of the vehicle on the driver's side Even if the portable device responds to a response request leaked in the vicinity of the passenger seat side of the response request, the door lock operation is not permitted. For this reason, a third party cannot actually open and close the door on the driver side opposite to the door on the passenger seat side where the user actually exists, and thus cannot get on. Therefore, even when radio waves directed to the communication area set on the vehicle side are propagated around the opposite side of the vehicle, crime prevention can be ensured.

In the above electronic key system, it is preferable to employ, for example, the following configuration in order to determine which of the first and second receiving antennas has received the response first.
That is, it is desirable that the distance between the first and second receiving antennas be set to be equal to or less than a half wavelength of the response signal. The vehicle also includes a receiving circuit that processes signals received by the first and second receiving antennas. The receiving circuit includes a mixer that mixes signals received by the first and second receiving antennas, a filter that removes high-frequency components from the signal mixed by the mixer, and a first receiving antenna that mixes the signals. And a switching circuit that is provided between the normal line and that switches a path of a signal received by the first receiving antenna between a normal line and a delay line that delays propagation of an electric signal from the normal line. . Then, the control circuit determines whether the portable device operates the vehicle based on the magnitude relationship between the output value of the filter when the signal path is switched to the normal line and the output value of the filter when the path is switched to the delay line. It is determined which side is the seat side or the passenger seat side.

  As described above, a case where a response from the driver's seat side is expected and the portable device is actually located on the passenger seat side will be described as an example. Further, it is assumed that the first receiving antenna is provided on the passenger seat side of the vehicle and the second receiving antenna is provided on the driver seat side. At this time, the response from the passenger seat side of the vehicle is first received by the first receiving antenna and then received by the second receiving antenna. That is, the phase of the response received by the first receiving antenna is ahead of the phase of the response received by the second receiving antenna.

  Here, when the signal received by the first receiving antenna is delayed by the delay line, the phase difference from the signal received by the second receiving antenna becomes small. For this reason, it can be determined that the phase of the signal received by the first receiving antenna is ahead of the phase of the signal received by the second receiving antenna. That is, the signal is propagated from the first receiving antenna side (the passenger seat side of the vehicle). The output value of the filter when the signal received by the first receiving antenna is delayed is larger than the output value of the filter when the signal received by the first receiving antenna is not delayed. This is because the output value of the filter can be expressed by a cosine function of the phase difference between the signal received by the first receiving antenna and the signal received by the second receiving antenna.

  Similarly, when a response from the passenger seat side is expected, and when the portable device is actually positioned on the driver seat side, the response from the driver seat side of the vehicle is first received by the second reception. Received by the antenna and then received by the first receive antenna. That is, the phase of the response received by the first receiving antenna is delayed from the phase of the response received by the second receiving antenna.

  Here, when the signal received by the first receiving antenna is delayed by the delay line, the phase difference from the signal received by the second receiving antenna becomes large. For this reason, it can be determined that the phase of the signal received by the first receiving antenna is delayed from the phase of the signal received by the second receiving antenna. That is, the signal is propagated from the second receiving antenna side (the vehicle driver's seat side) opposite to the first receiving antenna. The output value of the filter when the signal received by the first receiving antenna is delayed is smaller than the output value of the filter when the signal received by the first receiving antenna is not delayed.

  Thus, when the path of the signal received by the first receiving antenna is switched between the normal line and the delay line through the switching circuit, the level of the signal received by each of the first and second receiving antennas is changed. It can be seen that if the phase difference is small, the portable device is located on the passenger seat side, and if the phase difference is large, the portable device is located on the driver seat side.

  By setting the separation distance between the first and second receiving antennas to be equal to or less than the half wavelength of the response signal, the signals received by the first and second receiving antennas, respectively, and the phase difference between the two signals are set. , Each can be treated as a monotonically decreasing function.

  The electronic key system may be configured as follows. That is, the portable device has a detection circuit that detects the signal strength of the received response request, and transmits a response including information indicating the signal strength detected by the detection circuit. In the control circuit, the information indicating the signal strength included in the received response is transmitted to the opposite side of the driver side and the passenger side of the vehicle where the response from the portable device is originally expected. Only when the mobile device is within the threshold range set based on the probability of the vehicle being held, it is determined whether the portable device is located on the driver seat side or the passenger seat side.

  Thus, only when there is a probability that the response request is propagated to the side opposite to the side from which the response from the portable device is originally expected of the driver side and the passenger side of the vehicle, By determining which side is on the passenger seat side, the processing load of the control circuit is reduced as compared with the case where the processing related to the determination is always executed.

  Further, in the electronic key system, the control circuit permits the door lock operation when the operation of the door is detected in a state where the validity of the response from the portable device is confirmed, and the operation is performed. You may make it recognize the door side by which this is detected as a side by which the response from the said portable device is anticipated.

  In the electronic key system, the control circuit alternately transmits response requests to communication areas set around the driver side and passenger side of the vehicle, and transmits the response requests. The side may be recognized as a side where a response from the portable device is expected.

  According to the present invention, it is possible to ensure crime prevention even when a radio wave from a transmission antenna provided on a vehicle side portion propagates around the opposite vehicle side portion.

The block diagram which shows the structure of an electronic key system. The block diagram which shows the structure of a response signal. The top view of the vehicle which shows a communication area. The top view of the vehicle which shows a leak area. (A), (b) is a wave form diagram of a response signal received by vehicles. The block diagram which shows the non-adopted receiving circuit. The block diagram which shows the employ | adopted receiving circuit. The flowchart which shows the procedure of the validity determination process of an authentication process.

  Hereinafter, an embodiment of an electronic key system for a vehicle will be described. An electronic key system is a system for unlocking and locking a door of a vehicle through wireless communication between the vehicle and a portable device possessed by a user.

<Vehicle side configuration>
First, the configuration of the vehicle will be described.
As shown in FIG. 1, a touch sensor 12, a lock switch 13, and a door lock device 14 are connected to an ECU (electronic control device) 11 of the vehicle 10. The touch sensor 12 and the lock switch 13 are each provided on a door handle (not shown). The touch sensor 12 detects a touch on the door handle by the user. The touch sensor 12 is normally maintained in a stopped state. The lock switch 13 is pushed when the door is locked when getting off. The door lock device 14 performs locking and unlocking of the door, respectively.

  Further, the ECU 11 includes first and second transmission antennas 17 and 18 via first and second transmission circuits 15 and 16, and first and second reception antennas 20 and 21 via a reception circuit 19. Are connected to each other. The first transmission antenna 17 is provided on the right door of the vehicle 10, and the second transmission antenna 18 is provided on the left door of the vehicle 10. The receiving circuit 19 and the first and second receiving antennas 20 and 21 are respectively provided in the vehicle.

  The first and second transmission circuits 15 and 16 receive a response request signal Srq, which is a radio signal in the LF (Low Frequency) band, through the first and second transmission antennas 17 and 18 based on commands from the ECU 11, respectively. Calls to around 10 areas. The response request signal Srq is a command signal for requesting a response to the portable device 22 possessed by the user.

  The reception circuit 19 receives a UHF (Ultra High Frequency) band radio signal via the first and second reception antennas 20 and 21. Here, the radio signal in the UHF band refers to a response signal Srp transmitted from the portable device 22 in response to the response request signal Srq from the vehicle 10. The response signal Srp includes identification information unique to the portable device 22. The arrangement of the first and second receiving antennas 20 and 21 will be described in detail later.

  When the vehicle 10 is in a parked state (vehicle power is off, all doors are closed, doors are locked), the ECU 11 transmits a response request signal Srq through the first and second transmission antennas 17 and 18 with a period determined respectively. . In this example, the ECU 11 transmits the response request signal Srq alternately from the first and second transmission antennas 17 and 18. When the ECU 11 receives the response signal Srp from the portable device 22 through the receiving circuit 19, the ECU 11 compares the identification information of the portable device 22 included in the response signal Srp with the identification information stored in its own storage device 11a. . The ECU 11 activates the touch sensor 12 when verification of the identification information is established. When the touch to the door handle is detected through the touch sensor 12, the ECU 11 unlocks all the doors through the door lock device 14.

  The ECU 11 also responds through the first and second transmission antennas 17 and 18 when detecting that the lock switch 13 is operated in the parking state (vehicle power off, all doors closed, door unlocked). A request signal Srq is transmitted. When the ECU 11 receives the response signal Srp from the portable device 22 through the receiving circuit 19, the ECU 11 compares the identification information of the portable device 22 included in the response signal Srp with the identification information stored in its own storage device 11a. . The ECU 11 locks all the doors through the door lock device 14 when the verification of the identification information is established.

<Configuration of portable device>
Next, the configuration of the portable device will be described.
As shown in FIG. 1, a reception antenna 26 is connected to the control circuit 24 of the portable device 22 via a reception circuit 25, and a transmission antenna 28 is connected via a transmission circuit 27.

  The receiving circuit 25 receives a radio signal in the LF band, here a response request signal Srq from the vehicle 10 through the receiving antenna 26. The receiving circuit 25 has a detection circuit 29 that detects the received signal strength (RSSI) of the received radio signal.

The transmission circuit 27 transmits a UHF band radio signal, here a response signal Srp, through the transmission antenna 28 based on a command from the control circuit 24.
When the control circuit 24 receives the response request signal Srq through the receiving circuit 25, the control circuit 24 generates a response signal Srp and transmits the generated response signal Srp through the transmission antenna 28.

As shown in FIG. 2, the response signal Srp includes the identification information stored in its own storage device 24a and the RSSI value that is information indicating the signal strength of the received response request signal Srq.
<Communication area>
Next, the communication area will be described.

  As shown in FIG. 3, response request signals Srq are alternately transmitted from the first and second transmission antennas 17 and 18, so that the vehicle 10, the portable device 22, Communication areas 23, 23 are alternately formed. These communication areas 23 and 23 are areas where a response from the portable device 22 is expected, and the working distance of the portable device 22 (the portable device 22 is from the vehicle 10) required according to the product specifications of the electronic key system. The distance is set based on the distance to the vehicle 10 that can receive the transmitted radio signal.

  Ideally, the communication areas 23 and 23 formed around the left and right doors are formed only around the left and right doors, respectively. However, in order to obtain a desired communication area, as described above, the response request signal Srq transmitted from the first and second transmission antennas 17 and 18 provided on the left and right doors is provided by itself. There is a risk of spreading to the vicinity of the door on the opposite side of the door.

  As shown in FIG. 4, taking the communication area 23 formed around the right door as an example, the communication area 23 may protrude slightly from the left door. In the example of FIG. 4, as shown by hatching, when the vehicle 10 is viewed from the top, the first threshold line L1 indicating the outline of the communication area 23 around the right door (the operation limit of the portable device 22) When a response request signal Srq having a signal strength that enables the portable device 22 to operate within the range up to the second threshold line L2, the response request signal Srq leaks around the left door.

That is, when the signal strength V of the response request signal Srq is within the threshold range expressed by the following equation (1), the response request signal Srq is also propagated around the left door.
V _th1 <V <V _th2 (1)
However, V _th1 is the signal strength of the response request signal Srq in the first threshold line L1, and V _th2 is the signal strength of the response request signal Srq in the second threshold line L2.

  In spite of the timing at which the communication area 23 is originally formed only around the right door, a leak area 23a is formed as a result of the response request signal Srq being propagated even slightly around the left door on the opposite side. If there are, there are the following concerns. That is, the authentication of the portable device 22 located near the unintended left door enables the opening and closing of the right door on the opposite side. Unintentional opening and closing of the door is not preferable from the viewpoint of crime prevention. The same applies to the communication area 23 formed around the left door.

  Therefore, the ECU 11 determines whether the authentication of the portable device 22 is performed on the right side or the left side of the vehicle 10. The ECU 11 knows which of the first and second transmission antennas 17 and 18 is transmitting the radio signal from time to time. For this reason, if the ECU 11 knows the side of the vehicle 10 on which the portable device 22 has been authenticated, the ECU 11 can determine whether the authentication has been performed on the originally expected side. However, in this example, the ECU 11 recognizes the side of the door whose operation is detected through the touch sensor 12 as the side on which a response from the portable device 22 is expected. This is based on a crime prevention viewpoint in which the door is unlocked only when the user carrying the portable device 22 tries to open and close the door.

  In this example, in order to determine whether the authentication of the portable device 22 is performed on the right side or the left side of the vehicle 10, the first and second reception antennas 20 and 21 and the reception circuit 19 described above are used. It is provided as follows.

<Arrangement of UHF receiving antenna>
First, the arrangement of the first and second receiving antennas 20 and 21 will be described.
As shown in FIG. 4, the first and second receiving antennas 20 and 21 are provided, for example, at a driver seat side portion of an instrument panel in the vehicle. The first and second receiving antennas 20 and 21 are separated by a distance corresponding to a half wavelength or less of a radio signal in the UHF band in the vehicle width direction. The possible range of the separation distance D between the first and second receiving antennas 20 and 21 is 300 mm to 400 mm. In this example, the separation distance D is set to 300 mm. The first receiving antenna 20 is provided on the left side of the second receiving antenna 21.

  Since the mounting positions of the first and second receiving antennas 20 and 21 are different from each other, the timings at which the first and second receiving antennas 20 and 21 receive radio signals are slightly different.

  For example, when the response signal Srp is transmitted from the portable device 22 existing on the left side of the vehicle 10, the response signal Srp is first received by the first receiving antenna 20, and then is separated by the second receiving antenna 21 to the separation distance D. Received with a delay of the corresponding time. That is, as shown in the graph of FIG. 5A, the radio signal f (α) received by the first receiving antenna 20 and the radio signal f (β) received by the second receiving antenna 21 In the meantime, a phase difference Δθ corresponding to the separation distance D is generated. Similarly, when the response signal Srp is transmitted from the portable device 22 present on the right side of the vehicle 10, the response signal Srp is first received by the second receiving antenna 21 and then received by the first receiving antenna 20. . In this way, if it can be determined which of the first and second receiving antennas 20 and 21 received the radio signal earlier, whether the portable device 22 is located on the right side or the left side of the vehicle 10. Can be determined.

  As described above, the first and second receiving antennas 20 and 21 are provided along the vehicle width direction. Therefore, as shown in FIG. 4, when the portable device 22 is present on the extension line L3 of the first and second receiving antennas 20, 21 in the vehicle width direction, the first and second receiving antennas 20, The phase difference Δθ of the radio signal received at 21 is the largest.

  In this case, the phase difference Δθ between the two radio signals received by the first and second reception antennas 20 and 21 corresponds to the separation distance D between the first and second reception antennas 20 and 21.

The phase difference Δθ is expressed by the following equation (2).
Δθ = 360 ° (D / λ) (2)
However, “D” is a separation distance between the first and second receiving antennas 20 and 21, and “λ” is a wavelength.

  For example, when the frequency of the response signal Srp is 315 MHz, the wavelength of the response signal Srp is 950 mm, so the phase difference Δθ is about 114 °. Further, when the frequency of the response signal Srp is 433 MHz, the wavelength of the response signal Srp is 693 mm, so the phase difference is about 156 °.

  Thus, by setting the distance D between the first and second receiving antennas 20 and 21 to be equal to or less than the half wavelength (λ / 2) of the radio signal in the UHF band, the first and second receiving antennas 20 and 20 The phase difference Δθ of the response signal Srp received by 21 is always 180 ° or less.

  Here, as shown in the graph of FIG. 5B, the radio signals f (α) and f (β) in the UHF band are represented by periodic functions (here, cosine functions). For this reason, the same amplitude value appears twice in one wavelength (one period). For example, at time t1 and time t2, the amplitude is “−A / 2”. Then, the same amplitude value appears for the second time after exceeding the half wavelength (λ / 2). Therefore, the radio signals f (α) and f (β) can be treated as a monotonically decreasing function within a half wavelength. Since the phase and the amplitude correspond one-to-one, the phase (angle) is uniquely determined from the amplitude.

  The same applies to the phase difference Δθ. That is, as described later, the phase difference Δθ is represented by a cosine function. For this reason, if the phase difference Δθ is set to 180 ° or less at the maximum, the phase difference Δθ can be handled as a monotone decreasing function in the interval 0 ° to 180 °. For this reason, it is preferable to set the distance D between the first and second receiving antennas 20 and 21 to be equal to or less than a half wavelength of the radio signals f (α) and f (β) in the UHF band.

<Receiver circuit>
Next, the configuration of the receiving circuit will be described.
As shown in FIG. 6, the reception circuit 19 includes first and second amplifiers 31 and 32, a mixer (mixer) 33, and a filter 34. The first amplifier 31 is provided between the first receiving antenna 20 and the mixer 33. The second amplifier 32 is provided between the second receiving antenna 21 and the mixer 33. The filter 34 is provided between the mixer 33 and the ECU 11.

  The first amplifier 31 amplifies the radio signal f (α) received by the first receiving antenna 20. The second amplifier 32 amplifies the radio signal f (β) received by the second receiving antenna 21. Each of the first and second amplifiers 31 and 32 has an AGC (Automatic Gain Control) circuit (not shown). The AGC circuit automatically generates the first and second amplifiers 31 and 32 so that a constant output voltage can be obtained even when the amplitude of the electric signal input to the first and second amplifiers 31 and 32 varies. The amplification factor (gain) of 32 is adjusted.

The mixer 33 mixes (multiplies) the radio signals f (α) and f (β) amplified by the first and second amplifiers 31 and 32.
The filter 34 is a low-pass filter and removes a harmonic (second harmonic) component of the radio signal f (αβ) mixed by the mixer 33. The signal from which the harmonic component has been removed is taken into the ECU 11. The output of the filter 34 will be described in detail later.

<Filter output>
Next, the output of the filter 34 will be described.
The radio signal f (α) received by the first receiving antenna 20 is represented by the following equation (3), and the radio signal f (β) received by the second receiving antenna 21 is represented by the following equation (4). The

f (α) = Asin (ωt + θ) (3)
f (β) = Asin (ωt + θ + Δθ) (4)
However, “A” is the amplitude, “ω” is the angular frequency, “t” is the time, “ωt” is the frequency, “θ” is the initial phase, and “Δθ” is the radio signal f (α), f (β). It is a phase difference corresponding to the separation distance D.

Then, the radio signal f (αβ) mixed by the mixer 33 is expressed by the following equation (5).
f (αβ) = Asin (ωt + θ) · Asin (ωt + θ + Δθ) (5)
Equation (5) can be expressed as the following equation (6) using the addition theorem.

^{f (αβ) = (- A} 2/2) cos (2ωt + θ) + (A 2/2) cos (Δθ) ... (6)
As can be seen from the equation (6), since the frequencies of the two radio signals f (α) and f (β) are the same, when these radio signals f (α) and f (β) are mixed by the mixer 33, , Two components of the harmonic component represented by the first term and the component having no frequency difference represented by the second term are obtained.

  The filter 34 extracts a component having no frequency difference represented by the second term from the radio signal f (αβ) represented by Expression (6). That is, the filter 34 extracts information of only the phase difference Δθ according to the propagation distance from the portable device 22 to the first and second receiving antennas 20 and 21.

  As is clear from the equation (6), the phase difference Δθ is expressed by a cosine function. As described above, the phase difference Δθ is within a half wavelength of the two radio signals f (α) and f (β), that is, within 180 °. Therefore, as shown in FIGS. 5A and 5B, when the amplitudes of the two radio signals f (α) and f (β) change between “± A”, “−A˜ The amplitude value in the range of “A” can be uniquely replaced with the phase difference Δθ.

  However, even if the phase difference Δθ is known, it is unknown whether the radio signal comes from the left or right side of the vehicle 10. For example, when the portable device 22 is positioned on the extension line L3 in the vehicle width direction of the first and second receiving antennas 20 and 21, even if a radio signal is transmitted from either the left or right side of the vehicle 10, the phase difference Δθ Are the same. That is, it cannot be determined whether the response signal Srp from the portable device 22 is transmitted from the left or right of the vehicle 10. Therefore, the receiving circuit 19 shown in FIG. 6 is improved as follows.

  That is, as shown in FIG. 7, the receiving circuit 19 further includes a normal line (normal line) 35, a delay line (delay line) 36, and first and second switches 37 and 38. The normal line 35, the delay line 36, and the first and second switches 37 and 38 are provided between the first receiving antenna 20 and the first amplifier 31. The normal line 35 and the delay line 36 are provided in parallel between the first switch 37 and the second switch 38. The first and second switches 37 and 38 are so-called c contacts, and the contact state is switched based on a command from the ECU 11.

  The connection path between the first receiving antenna 20 and the first amplifier 31 is switched between the normal line 35 and the delay line 36 through the switching of the first and second switches 37 and 38. Here, the path where the first receiving antenna 20 is connected to the first amplifier 31 via the normal line 35 is the first path, and the first amplifier 31 is connected via the delay line 36 to the first amplifier 31. The path connected to is called the second path. Usually, the first and second switches 37 and 38 maintain the connection path between the first receiving antenna 20 and the first amplifier 31 in the first path. The delay line 36 is a component that delays the electric wave of the electric signal. In this example, the delay line 36 delays the phase of the electric signal by 10 °.

  By configuring the receiving circuit 19 in this manner, the received radio signal (response signal Srp) is transmitted from the first receiving antenna 20 side or transmitted from the second receiving antenna 21 side. It becomes possible to determine whether or not. In other words, it is possible to determine whether the portable device 22 is located on the driver's seat side or the passenger seat side of the vehicle 10.

<Positioning method of portable device>
Next, a method for determining the position of the portable device 22 will be described. Here, as shown in FIG. 4, the case where the regular communication area 23 is formed around the right door will be described as an example. A leakage area 23a is formed around the left door.

  Now, when the portable device 22 is located in the leak area 23a formed around the left door, the response signal Srp from the portable device 22 propagates from the left side of the vehicle 10. The response signal Srp from the left side of the vehicle 10 is first received by the first receiving antenna 20 and then received by the second receiving antenna 21. That is, the phase of the response signal Srp received by the first receiving antenna 20 is ahead of the phase of the response signal Srp received by the second receiving antenna 21.

  Here, the phase difference Δθ when the radio signal f (α) received by the first receiving antenna 20 is delayed by the delay line 36 is smaller than when the delay is not delayed. Therefore, it can be determined that the phase of the radio signal f (α) received by the first receiving antenna 20 is ahead of the phase of the radio signal f (β) received by the second receiving antenna 21. That is, the radio signal propagates from the first receiving antenna 20 side (left side of the vehicle 10). At this time, the output value of the filter 34 represented by the second term of the equation (6) is larger than the output value of the filter 34 when the radio signal f (α) is not delayed. This is because the value of cos (Δθ) increases as the phase difference Δθ decreases.

  Further, when the portable device 22 is located in a regular communication area 23 formed around the right door, the response signal Srp from the portable device 22 propagates from the right side of the vehicle 10. The response signal Srp from the right side of the vehicle 10 is first received by the second receiving antenna 21 and then received by the first receiving antenna 20. That is, the phase of the response signal Srp received by the first receiving antenna 20 is delayed from the phase of the response signal Srp received by the second receiving antenna 21.

  Here, the phase difference Δθ when the radio signal f (α) received by the first receiving antenna 20 is delayed by the delay line 36 becomes larger than when the delay is not performed. Therefore, it can be determined that the phase of the radio signal f (α) received by the first receiving antenna 20 is delayed from the phase of the radio signal f (β) received by the second receiving antenna 21. That is, the radio signal propagates from the second receiving antenna 21 side (the right side of the vehicle 10). At this time, the output value of the filter 34 represented by the second term of the equation (6) is smaller than the output value of the filter 34 when the radio signal f (α) is not delayed. This is because the value of cos (Δθ) decreases as the phase difference Δθ increases.

  That is, the first and second switches 37 and 38 change the connection path between the first receiving antenna 20 and the first amplifier 31 from the normal line 35 (first path) to the delay line 36 (second line). When the phase difference Δθ decreases, the radio signal propagates from the first receiving antenna 20 side. When the phase difference Δθ further increases, the second receiving antenna 21 side switches. A radio signal is propagated.

As described above, since the phase difference Δθ is expressed by a cosine function, if the phase difference Δθ is 180 ° or less at the maximum, it can be treated as a monotonically decreasing function in the range of 0 ° to 180 °.
Therefore, the phase advance or delay can be determined by performing the operation (B) after satisfying the following condition (A).

  (A) By making the separation distance D between the first and second receiving antennas 20 and 21 slightly shorter than the half wavelength of the radio signal (response signal Srp) in the UHF band (D = 300 mm in this example), The phase difference Δθ should be 170 ° or less at maximum.

  (B) The connection path between the first receiving antenna 20 and the first amplifier 31 is delayed by 10 ° from the normal line 35 (first path) through the first and second switches 37 and 38. Switch to line 36 (second path).

  Incidentally, when the phase difference Δθ is the smallest, the response signal Srp is transmitted from the portable device 22 located near the rear wheel. However, even if the phase difference Δθ becomes small, the amount of change in the cosine function is only small, and the phase advance or delay can be determined. When the phase difference Δθ is maximized, it is possible to determine whether the phase is advanced or delayed as long as the interval is monotonically decreasing. That is, the connection path between the first receiving antenna 20 and the first amplifier 31 through the first and second switches 37 and 38 is a delay line corresponding to 10 ° from the normal line 35 (first path). When switching to 36 (second path), if the output value of the filter 34 shown in the second term of the equation (6) becomes large, the radio signal from the first receiving antenna 20 side, the output value of the filter 34 is also the same. Can be determined as a radio signal from the second receiving antenna 21 side.

  Thus, by determining whether the UHF band radio signal has propagated from the left or right side of the vehicle 10, the portable device 22 is activated on the side of the vehicle 10 where the response is expected (the door side where the operation is detected). It can be determined whether or not

  The ECU 11 invalidates the authentication (verification of identification information) when it is determined that the mobile device 22 has been authenticated on the side where no response is expected. Thereby, it is suppressed based on the response signal Srp from the portable device 22 that the door is unlocked.

<Validity / invalidity judgment processing of collation processing>
Next, the procedure of the validity / invalidity determination process of the collation process with the portable device 22 by the ECU 11 will be described with reference to the flowchart of FIG. Each process according to the flowchart is executed when the response signal Srp is received.

  First, the ECU 11 determines the signal strength V of the response request signal Srq received by the portable device 22 based on the RSSI value included in the response signal Srp (step S101). That is, the ECU 11 determines whether or not there is a probability that the signal strength V of the response request signal Srq received by the portable device 22 propagates around the door on the side opposite to the side on which the original communication area 23 is formed.

  When the signal intensity V of the response request signal Srq satisfies the relationship of the above-described equation (1), the ECU 11 determines whether or not the driver side door (in this example, the right door) has been operated (step S102). .

  The ECU 11 switches the first and second switches 37 and 38 when the operation of the driver side door is detected through the touch sensor 12 provided on the driver side door handle (YES in step S102). .

  The ECU 11 sets the contact state of the first and second switches 37 and 38 so that the connection path between the first receiving antenna 20 and the first amplifier 31 is the normal line 35 (step S103). . The ECU 11 takes in the output value Va of the filter 34 at this time (step S104).

  Next, the ECU 11 sets the contact state of the first and second switches 37 and 38 so that the connection path between the first receiving antenna 20 and the first amplifier 31 becomes the delay line 36 ( Step S105). The ECU 11 takes in the output value Vb of the filter 34 at this time (step S106).

The ECU 11 determines the magnitude relationship between the two captured output values Va and Vb (step S107).
When the output value Va is smaller than the output value Vb (YES in step S107), the ECU 11 invalidates the authentication process of the portable device 22 performed earlier, that is, the identification information collation process (step S108), and unlocks the door. The process is terminated without doing so. This is because, as described above, when the output value of the filter 34 increases before and after the addition of the delay line 36, it can be said that the portable device 22 is located in the leakage area 23a on the passenger seat side (left door side). . With this process, the door on the driver's seat side is prevented from being opened and closed despite the presence of the portable device 22 on the passenger seat side of the vehicle 10.

  When the output value Va is larger than the output value Vb (NO in step S107), the ECU 11 validates the authentication process of the portable device 22 performed earlier, that is, the identification information matching process (step S109). As described above, when the output value of the filter 34 decreases before and after the addition of the delay line 36, it can be said that the portable device 22 is located in the regular communication area 23 on the driver's seat side (right door side). It is.

Thereafter, the ECU 11 unlocks the door (step S110) and ends the process.
Further, when the operation of the door on the driver's seat side is not detected (NO in step S102), the ECU 11 determines whether or not the door on the passenger seat side (in this example, the left door) has been operated (step S111). .

  When the operation of the door on the passenger seat side is detected through the touch sensor 12 provided on the door handle on the passenger seat side (YES in step S111), the ECU 11 performs the same as the processing in the previous steps S103 to S106. The first and second switches 37 and 38 are switched.

  That is, the ECU 11 sets the connection path between the first receiving antenna 20 and the first amplifier 31 to the normal line 35 through the first and second switches 37 and 38 (step S112). The output value Va of the filter 34 is taken in (step S113).

  Next, the ECU 11 sets the connection path between the first receiving antenna 20 and the first amplifier 31 to the delay line 36 through the first and second switches 37 and 38 (step S114). The output value Vb of the filter 34 is taken in (step S115).

Next, the ECU 11 determines the magnitude relationship between the two captured output values Va and Vb (step S116).
When the output value Va is larger than the output value Vb (NO in step S116), the ECU 11 invalidates the authentication process of the portable device 22 that has been performed earlier, that is, the identification information collation process (step S108), and unlocks the door. The process is terminated without doing so. This is because, as described above, when the output value of the filter 34 decreases before and after the addition of the delay line 36, it can be said that the portable device 22 is located in the leakage area 23a on the driver's seat side (right door side). . With this process, the opening and closing of the door on the passenger seat side is suppressed despite the presence of the portable device 22 on the driver seat side of the vehicle 10.

  When the output value Va is smaller than the output value Vb (YES in step S116), the ECU 11 validates the authentication process of the portable device 22 performed earlier, that is, the identification information collation process (step S108). As described above, when the output value of the filter 34 increases before and after the addition of the delay line 36, it can be said that the portable device 22 is located in the regular communication area 23 on the passenger seat side (left door side). It is.

Thereafter, the ECU 11 unlocks the door (step S110) and ends the process.
In step S111, when the operation of the door on the passenger seat side is not detected (NO in step S111), the ECU 11 ends the process. The absence of left and right door operations means that there is no intention to get on.

Further, in the previous step S101, the ECU 11 also when the signal strength V does not satisfy the relationship of the above formula (1), that is, when the signal strength V is equal to or lower than the signal strength V _th1 or equal to or higher than the signal strength V _th2. The process is terminated.

If the signal strength V of the response request signal Srq is a high intensity of the signal strength V _th2 or more, rather than the response from the leak area 23a, it is apparent that the portable unit 22 to the side where the original response is expected positions. For this reason, a normal unlocking process may be performed. That is, when the collation between the identification information included in the response signal Srp and the identification information stored in its own storage device 11a is established, the ECU 11 detects the operation of the door through the touch sensor 12 as shown in FIG. The door is unlocked without executing the processing according to the flowchart. Also, if the signal strength V of the response request signal Srq is a weak intensity of the signal strength V _th1 or less, it can be said that the portable device 22 is located outside the normal communication area 23.

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) The vehicle 10 includes first and second receiving antennas 20 and 21 provided at intervals in the vehicle width direction. The ECU 11 determines that the portable device 22 is on the driver seat side (right side in this example) and the passenger seat side (in this example) of the vehicle 10 based on which of the first and second receiving antennas 20 and 21 has received the response first. Determine which side is on the left side. Then, the ECU 11 permits the operation of the door lock device 14 when the determination result matches the side on which the response from the portable device 22 is originally expected, and does not permit the operation of the door lock device 14 when they do not match. In this example, the side on which the response from the portable device 22 is expected refers to the side of the door where the operation is detected through the touch sensor 12. In other words, in this example, the door is not unlocked unless the portable device 22 is on the same side of the vehicle 10 as the door whose operation is detected through the touch sensor 12. Thus, crime prevention is ensured by restricting the operation of the door lock device 14 when the portable device 22 is positioned on the side of the vehicle 10 where no response is expected.

  (2) In order to determine which of the first and second receiving antennas 20 and 21 has received the response signal Srp first, for example, the following configuration is employed. That is, the separation distance D between the first and second reception antennas 20 and 21 is set to be equal to or less than a half wavelength of the response signal Srp. Further, the receiving circuit 19 of the vehicle 10 is provided between the first receiving antenna 20 and the mixer 33, and the path of the signal received by the first receiving antenna 20 is routed through the normal line 35 and the delay line 36. First and second switches 37 and 38 for switching between the first and second switches are provided. The ECU 11 calculates the output value of the filter 34 when the path of the signal received by the first receiving antenna 20 is switched to the normal line 35 and the output value of the filter 34 when the path is switched to the delay line 36. Based on the magnitude relationship, it is determined whether the portable device 22 is located on the driver seat side or the passenger seat side of the vehicle 10.

  When the path of a signal received by the first receiving antenna 20 is switched between the normal line 35 and the delay line 36 through the first and second switches 37 and 38, the first and second receiving antennas 20 are used. , 21 when the phase difference Δθ of the received signals is small, the portable device 22 is located on the passenger seat side. Similarly, when the phase difference Δθ is large, the portable device 22 is located on the driver seat side. In addition, by setting the separation distance D between the first and second receiving antennas 20 and 21 to be equal to or less than a half wavelength of the response signal Srp, the signals received by the first and second receiving antennas 20 and 21, respectively, The phase difference Δθ between these two signals can be treated as a monotone decreasing function.

  (3) The portable device 22 includes a detection circuit 29 that detects the signal strength of the received response request signal Srq, and transmits a response signal Srp including information indicating the signal strength detected by the detection circuit 29. Then, the ECU 11 requests that the information indicating the signal strength included in the received response signal Srp be a response request from the driver seat side and the passenger seat side of the vehicle 10 to the side opposite to the side where the response from the portable device 22 is originally expected. Only when the signal Srq is within a threshold range set based on the probability of propagation, it is determined whether the portable device 22 is located on the driver seat side or the passenger seat side of the vehicle 10.

  Thus, only when there is a probability that the response request signal Srq is propagated to the side opposite to the side where the response from the portable device 22 is originally expected on the driver seat side and the passenger seat side of the vehicle 10, the portable device 22 is the vehicle. By determining which side is the driver's seat side or the passenger's seat side, the processing load on the ECU 11 is reduced as compared with the case where the processing related to the determination is always executed.

<Other embodiments>
The embodiment described above may be modified as follows.
In this example, the detection circuit 29 for detecting the received signal strength is provided in the portable device 22, but the detection circuit 29 may be omitted. In this case, the process of step S101 in the flowchart of FIG. That is, each process according to the flowchart of FIG. 8 is executed at a predetermined control period regardless of the probability that the leakage area 23a is formed. Even if it does in this way, the effect of (1)-(3) of this Embodiment is acquired.

  In this example, the first and second receiving antennas 20 and 21 are provided at intervals in the vehicle width direction, and the ECU 11 receives the response signal Srp first, which of the first and second receiving antennas 20 and 21 is first. Whether or not the portable device 22 is located on the driver seat side or the passenger seat side of the vehicle 10 is determined based on whether or not the vehicle 10 is on, but other determination methods may be employed. Even if it does in this way, the effect of (1)-(3) of this Embodiment is acquired.

  In this example, a so-called trigger-type electronic key system that permits the operation of the door lock device 14 when the operation of the door handle is detected when authentication of the portable device 22 is established through wireless communication is taken as an example. However, the following electronic key system may be used. That is, in the electronic key system, when the portable device 22 enters the communication areas 23 and 23 set around the left and right doors of the vehicle 10, it is automatically performed between the vehicle 10 and the portable device 22. The door is automatically unlocked through transmission and reception of radio signals. In this case, the vehicle 10 transmits response request signals Srq alternately around the left and right doors. The communication area 23 on the side where the response request signal Srq is transmitted is the side on which a response from the portable device 22 is expected. Even if it does in this way, the effect of (1)-(3) of this Embodiment is acquired.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Electronic control circuit, 14 ... Door lock device, 19 ... Reception circuit, 20 ... 1st reception antenna, 21 ... 2nd reception antenna, 22 ... Portable machine, 23 ... Communication area, 33 ... Mixing 34, filter, 35 ... normal line, 36 ... delay line, 37 ... first switch constituting the switching circuit, 38 ... second switch constituting the switching circuit.

Claims (5)

An in-vehicle device that transmits a response request to a communication area set around at least the side of the driver's seat side of the vehicle and permits the operation of the vehicle door lock when a response is received from the portable device in response to the response request. In an electronic key system having a control circuit of
The vehicle has first and second receiving antennas provided at intervals in the vehicle width direction,
The control circuit determines whether the portable device is located on the driver seat side or the passenger seat side of the vehicle based on which of the first and second receiving antennas has received the response first, An electronic key system that permits door lock operation when the determination result matches the side on which a response from the portable device is expected, and does not permit door lock operation when the response does not match. The electronic key system according to claim 1.
The separation distance between the first and second receiving antennas is set to a half wavelength or less of the response signal,
The vehicle has a receiving circuit for processing signals received by the first and second receiving antennas,
The receiving circuit is mixed with a mixer that mixes signals received by the first and second receiving antennas, a filter that removes high-frequency components from the signal mixed by the mixer, and a first receiving antenna. A switching circuit for switching a path of a signal received by the first receiving antenna between a normal line and a delay line that delays propagation of an electric signal from the normal line,
The control circuit determines whether the portable device is on the driver's seat side of the vehicle based on the magnitude relationship between the output value of the filter when the signal path is switched to the normal line and the output value of the filter when the path is also switched to the delay line. And electronic key system that determines which side is on the passenger side. The electronic key system according to claim 1 or 2,
The portable device has a detection circuit that detects the signal strength of the received response request, and transmits a response including information indicating the signal strength detected by the detection circuit,
In the control circuit, the information indicating the signal strength included in the received response is likely to be transmitted to the opposite side of the driver side and the passenger side of the vehicle where the response from the mobile device is expected. An electronic key system that determines whether the portable device is located on the driver side or the passenger side of the vehicle only when it is within the threshold range set based on In the electronic key system according to any one of claims 1 to 3,
The control circuit permits the operation of the door lock when the operation of the door is detected in a state where the validity of the response from the portable device is confirmed, and the door side where the operation is detected is detected. An electronic key system that recognizes a response from the portable device as an expected side. In the electronic key system according to any one of claims 1 to 3,
The control circuit alternately sends response requests to communication areas set around the sides of the driver side and passenger side of the vehicle, and the side that sent the response request is sent from the portable device. An electronic key system that is recognized as the expected response.