JP4750585B2 - Electronic key communication device and electronic key communication system - Google Patents

Description

  The present invention relates to an electronic key communication apparatus and an electronic key communication system that exchange various data with an electronic key by wireless communication.

  In recent years, many vehicles are equipped with a hands-free system (for example, Patent Document 1) that permits locking / unlocking of a vehicle and starting of an engine without actually performing a key operation using a vehicle key. . This hands-free system transmits a request signal from a transmitter of a vehicle, receives an ID code signal returned from the portable device in response to the request signal, and receives the ID code signal at the time of receiving the ID code signal. The ID code on the vehicle side is matched with the ID code on the vehicle side, and if these ID codes match and ID collation is established, door locking / unlocking and engine starting are permitted.

  As shown in FIG. 7, in this type of hands-free system, it is necessary to determine whether the portable device exists outside the vehicle or inside the vehicle. An out-of-vehicle LF transmitter 51 is disposed at a door or the like, and an in-vehicle LF transmitter 52 is disposed under the floor in the vehicle.

  The out-of-vehicle LF transmitter 51 is provided with an out-of-vehicle antenna 53 capable of transmitting a request signal to the outside of the vehicle. The vehicle exterior antenna 53 includes a series circuit of a coil 54 and a capacitor 55, and the antenna transmission frequency is determined by the values of the coil 54 and the capacitor 55. A vehicle exterior antenna drive circuit 57 is connected to the vehicle exterior antenna 53 with a vehicle exterior antenna output adjustment resistor 56 connected in series. A first FET 58 is connected between the outside antenna 53 and the outside antenna drive circuit 57. The first FET 58 is an element that switches on / off of the current flowing through the vehicle exterior antenna circuit 59 including the vehicle exterior antenna 53, the vehicle exterior antenna output adjustment resistor 56, and the vehicle exterior antenna drive circuit 57.

  The in-vehicle LF transmitter 52 is provided with an in-vehicle antenna 60 capable of transmitting a request signal into the vehicle. The vehicle interior antenna 60 also includes a series circuit of a coil 61 and a capacitor 62, and the antenna transmission frequency is determined by the values of the coil 61 and the capacitor 62. A vehicle interior antenna drive circuit 64 is connected to the vehicle interior antenna 60 with a vehicle interior antenna output adjustment resistor 63 connected in series. A second FET 65 is connected between the vehicle interior antenna 60 and the vehicle interior antenna drive circuit 64. The second FET 65 is an element that switches on / off of a current flowing through the vehicle interior antenna circuit 66 including the vehicle interior antenna 60, the vehicle interior antenna output adjustment resistor 63, and the vehicle interior antenna drive circuit 64.

  When performing in-vehicle collation to determine whether or not the portable device is in the vehicle, a microcomputer (not shown) that controls the hands-free system generates a rectangular wave to the in-vehicle antenna drive circuit 64 so that a request signal is transmitted from the in-vehicle antenna 60. Then, the antenna current I1 shown in FIG. At this time, the microcomputer turns on the second FET 65 during the request signal transmission period and closes the vehicle interior antenna circuit 66 as shown in FIG. 8B. As a result, the vehicle interior antenna 60 transmits a request signal in accordance with the waveform of the antenna current I1 shown in FIG.

  Here, when the in-vehicle antenna 60 transmits a request signal, a part of the antenna current I1 flowing in the in-vehicle antenna circuit 66 goes around to the out-of-vehicle antenna circuit 59 via GND, and flows into the out-of-vehicle antenna 53 as a wrap-around current. There is. If a sneak current flows through the outside antenna circuit 59, the outside antenna 53 is also in a state of transmitting a request signal. To avoid this, the microcomputer transmits a request signal from the in-vehicle antenna 60. The first FET 58 is turned off to prevent current from flowing.

When the portable device receives the request signal conforming to the antenna current I1 shown in FIG. 8A, the portable device demodulates the request signal and enters the reception data D1 of the rectangular wave shown in FIG. 8C. The portable device decodes the received data D1 and, if the received data D1 is a waveform representing an ID code reply request, transmits its ID code as an ID code signal to the vehicle receiver in response thereto. Note that the same operation is performed when a request signal is transmitted from an antenna outside the vehicle when performing outside-vehicle verification for determining whether or not the portable device is outside the vehicle.
JP 2002-029385 A

  However, in this type of hands-free system, since the vehicle exterior antenna drive circuit 57 and the vehicle interior antenna drive circuit 64 are provided on the same printed circuit board, a current flows through one of the vehicle exterior antenna circuit 59 and the vehicle interior antenna circuit 66. In some cases, a coupling current flows through the other circuit due to a magnetic field generated in the circuit through which the current flows. For example, when the antenna current I1 shown in FIG. 8 (a) flows through the in-vehicle antenna circuit 66, the coupling current I2 shown in FIG. 9 (a) in phase with the antenna current I1 is shown in FIG. 9 (b). In this way, the first FET 58 is in a state of flowing to the outside antenna 53 even though it is not turned on.

  As a result, the request signal is transmitted not only from the vehicle interior antenna 60 but also from the vehicle exterior antenna 53, even though the vehicle interior verification is performed. Therefore, even if the portable device is located outside the vehicle when in-vehicle collation is performed, the portable device receives a request signal from the antenna 53 outside the vehicle, and has a code waveform similar to that shown in FIG. ), The portable device returns its own ID code signal to the vehicle. For this reason, since in-vehicle collation is established by a portable device outside the vehicle, there is a problem in that an erroneous determination occurs when determining the position of the portable device.

  In this type of hands-free system, a harness connecting the vehicle exterior antenna drive circuit 57 and the vehicle exterior antenna 53 and a harness connecting the vehicle interior antenna drive circuit 64 and the vehicle interior antenna 60 are running side by side. Therefore, when a current flows through one harness of the outside antenna circuit 59 and the inside antenna circuit 66, a coupling current flows through the harness of the other circuit due to a magnetic field generated in the harness through which the current flows. And the in-vehicle antenna 60 cause the request signal to be transmitted.

  An object of the present invention is to provide an electronic key communication device and an electronic key communication system that can prevent erroneous communication with an electronic key.

In order to solve the above problems, according to the present invention, a plurality of antenna driving circuits provided for each of a plurality of antennas and a plurality of antenna driving circuits provided to turn on and off the power of each antenna circuit of the antennas are provided. A plurality of switching elements, and a communication control circuit for controlling on / off of the switching elements while controlling the driving of the antenna via the antenna driving circuit, and the electronic key receives a transmission signal transmitted by the antenna. In the electronic key communication apparatus in which the electronic key acquires the transmission signal as reception data, when the transmission signal is transmitted from the antenna to be driven among the plurality of antennas, the antenna driving circuit on the driving antenna side is driven. Sending a command and sending the switching element on the side of the driving antenna to the signal transmission period Oite ON, the standby antenna not driven, the switching element of the standby antenna, comprising a control means for on-off at least once in the signaling period, the driving antenna, installed in outdoor entering and leaving the subject The gist is that it is one of an outdoor antenna and an indoor antenna installed in the room to be moved in and out, and the standby antenna is the other of the outdoor antenna and the indoor antenna .

  According to this configuration, when the transmission signal is transmitted from the drive antenna among the plurality of antennas, the communication control circuit outputs a drive command to the antenna drive circuit connected to the drive antenna and the switching element connected to the drive antenna. Is turned on during the signal transmission period. As a result, an antenna current corresponding to the drive command flows through the antenna circuit of the drive antenna, and a transmission signal having data contents corresponding to the drive command is transmitted from the drive antenna.

  Here, when an antenna current flows through the drive antenna, a magnetic field is generated around the antenna circuit of this drive antenna. Therefore, the standby antenna is affected by this magnetic field, and a coupling current flows through the antenna circuit of the standby antenna. A transmission signal may be transmitted from the standby antenna due to the current. In this case, the electronic key actually receives the transmission signal transmitted from the drive antenna as the transmission signal output from the standby antenna, and there is a communication error between the electronic key and the antenna. It becomes.

  However, in the present invention, when the driving antenna transmits a transmission signal, the control unit turns on and off the switching element of the standby antenna at least once during the period in which the driving antenna transmits the transmission signal. As a result, even when a coupling current flows through the standby antenna, a current having a waveform different from the antenna current flowing through the drive antenna flows through the antenna circuit of the standby antenna. Therefore, even if a transmission signal is transmitted from the standby antenna, this transmission signal is transmitted as a signal having a waveform different from that of the transmission signal transmitted from the drive antenna.

  Therefore, even if the electronic key receives a transmission signal from the standby antenna, the electronic key receives a transmission signal having a waveform different from that of the transmission signal that can be received from the drive antenna. Therefore, the electronic key is a transmission signal received from the standby antenna, and it is not necessary to perform the same operation as when the transmission signal is received from the drive antenna, so that erroneous communication is unlikely to occur between the electronic key and the antenna. .

  According to the present invention, a plurality of antenna driving circuits provided for each of a plurality of antennas, a plurality of switching elements provided for each of the antenna driving circuits so as to turn on and off each antenna circuit of the antennas, and the antennas A communication control circuit that controls driving of the antenna via the drive circuit and controls on / off of the switching element, and when the electronic key receives a transmission signal transmitted by the antenna, the electronic key transmits the transmission signal. In the electronic key communication device for acquiring the received data as the received data, at least one of the switching elements, an antenna output adjusting element for attenuating the antenna output connected in parallel with the switching element, and the antenna output adjusting element connected in series Antenna output adjustment switching element and the plurality of antennas When transmitting the transmission signal using the antenna to which the antenna output adjustment element is not connected as a drive antenna, a drive command is sent to the antenna drive circuit on the drive antenna side and the switching element on the drive antenna side is used as the signal. For a standby antenna that is turned on in the transmission period and is not driven and connected to the antenna output adjustment element, the switching element of the standby antenna is turned off and the antenna output adjustment switching element is turned on at least once in the signal transmission period. The gist of the present invention is that it includes control means for turning on and off.

  According to this configuration, for example, depending on the signal strength of the antenna, the communication area of the standby antenna enters the communication area of the drive antenna, and when the electronic key is located in an area where this area overlaps, the transmission signal transmitted by the drive antenna, The electronic key may receive a signal superimposed with a transmission signal transmitted from the standby antenna.

  In this case, for example, if the signal strength of the transmission signal transmitted from the standby antenna is stronger than that of the transmission signal transmitted from the drive antenna, the reception data received by the electronic key at this time is close to the transmission signal transmitted from the standby antenna. It will be a thing. Therefore, in a situation where the electronic key receives a signal in which a transmission signal transmitted from the driving antenna and a transmission signal transmitted from the standby antenna are superimposed, it is also desirable to receive the transmission signal transmitted from the driving antenna with the electronic key. Nevertheless, there is a problem that it cannot be received.

  However, in the present invention, when a transmission signal having a waveform different from that of the transmission signal transmitted from the drive antenna is transmitted from the standby antenna, the energization of the circuit including the antenna output adjustment element for attenuation of the antenna output is switched to the antenna output adjustment switching. The device is turned on and off by turning it on and off. As a result, a signal having a waveform different from that of the transmission signal transmitted from the drive antenna is transmitted from the standby antenna.

  Therefore, a transmission signal transmitted from the standby antenna is transmitted from the standby antenna as a signal having a low signal strength. Therefore, even when the electronic key receives a signal in which the transmission signal transmitted from the driving antenna and the transmission signal transmitted from the standby antenna are superimposed, the electronic key receives the transmission signal that approaches the driving antenna. It becomes a state, and is effective in preventing erroneous communication in communication between the electronic key and the antenna.

  According to the present invention, the drive antenna is any one of an outdoor antenna installed outside the room to be entered and exited and an indoor antenna installed in the room to be entered and exited, and the standby antenna is The gist is the other of the outdoor antenna and the indoor antenna.

According to this configuration, it is possible to determine whether the electronic key is located indoors or outdoors, and it is difficult for erroneous determination to occur when the electronic key position is determined.
According to the present invention, the drive antenna is any one of an outdoor antenna installed outside the room to be entered and exited and an indoor antenna installed in the room to be entered and exited, and the standby antenna is The other of the outdoor antenna and the indoor antenna, and the series circuit including the antenna output adjustment element and the antenna output adjustment switching element is connected in parallel to the switching element of the outdoor antenna. The gist.

  According to this configuration, it is possible to determine whether the electronic key is located indoors or outdoors, and it is difficult for erroneous determination to occur when the electronic key position is determined. In addition, even if the electronic key is located in the indoor part and can receive a transmission signal from both the drive antenna and the standby antenna, a situation may occur in which the electronic key is erroneously determined to be outside the room. It can also be made difficult.

According to the present invention, a plurality of antenna driving circuits provided for each of a plurality of antennas, a plurality of switching elements provided for each of the antenna driving circuits so as to turn on and off each antenna circuit of the antennas, and the antennas When receiving a transmission signal transmitted from the antenna, and a communication unit having a communication control circuit for performing on / off control of the switching element and controlling the driving of the antenna via a drive circuit, the transmission signal is used as reception data. In an electronic key communication system including an electronic key to be acquired, when the transmission signal is transmitted from an antenna to be driven among the plurality of antennas, a drive command is sent to the antenna drive circuit on the drive antenna side and the drive antenna The switching element on the side is turned on during the signal transmission period. Outdoor The standby antenna not driven, the switching element of the standby antenna, provided a control means for turning on and off at least once in the signaling period to the communication unit, the driving antenna, which is installed outdoors of entry and exit target The gist is that the antenna is one of an antenna and an indoor antenna installed in the room to be moved in and out, and the standby antenna is the other of the outdoor antenna and the indoor antenna .

  According to the present invention, a plurality of antenna driving circuits provided for each of a plurality of antennas, a plurality of switching elements provided for each of the antenna driving circuits so as to turn on and off each antenna circuit of the antennas, and the antennas When receiving a transmission signal transmitted from the antenna, and a communication unit having a communication control circuit for performing on / off control of the switching element and controlling the driving of the antenna via a drive circuit, the transmission signal is used as reception data. In an electronic key communication system comprising an electronic key to be acquired, at least one of the switching elements includes an antenna output adjustment element for reducing antenna output attenuation connected in parallel with the switching element, and the antenna output adjustment element. A plurality of antenna output adjustment switching elements connected in series; When transmitting the transmission signal using the antenna to which the antenna output adjustment element is not connected as a drive antenna among the antennas, a drive command is sent to the antenna drive circuit on the drive antenna side and the switching element on the drive antenna side For the standby antenna that is turned on in the signal transmission period and is not driven, to which the antenna output adjustment element is connected, the switching element of the standby antenna is turned off, and the antenna output adjustment switching element is turned on in the signal transmission period. The gist of the invention is that the communication unit is provided with control means for turning on and off at least once.

  According to the present invention, it is possible to prevent erroneous communication with the electronic key.

(First embodiment)
A first embodiment of an electronic key communication device and an electronic key communication system embodying the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the vehicle 1 is equipped with a hands-free system 2 that can perform door locking / unlocking and engine starting without actually operating a vehicle key. The hands-free system 2 transmits a request signal Sreq from the vehicle 1, and when the portable device 3 receives the request signal Sreq, the portable device 3 responds to the ID signal Sid with the ID code on the vehicle 1 in response. In response, when the ID code of the portable device 3 matches the ID code of the vehicle 1, door locking / unlocking and engine starting are permitted. The portable device 3 corresponds to an electronic key.

  The hands-free system 2 will be described below. The vehicle 1 is provided with a smart ECU 4 that performs ID collation with the portable device 3 used as a vehicle key. Connected to the smart ECU 4 are an out-of-vehicle LF transmitter 5 capable of transmitting an LF band signal outside the vehicle and an out-of-vehicle LF transmitter 5 capable of transmitting an LF band signal into the vehicle. A plurality of outside LF transmitters 5 are installed outside the vehicle such as each side door or luggage door of the vehicle 1. A plurality of in-vehicle LF transmitters 6 are installed, for example, under the floor in the vehicle. The smart ECU 4 constitutes a communication control circuit and control means.

The smart ECU 4 is connected to an RF receiver 7 that can receive an RF band signal. The RF receiver 7 is embedded in, for example, a rearview mirror in the vehicle.
The smart ECU 4 is connected to, for example, a touch sensor 8 embedded in a vehicle handle knob or the like. The touch sensor 8 is a sensor that detects an operation of touching the handle knob when the operator releases the locked door lock. For example, a lock button 9 provided on a handle knob is connected to the smart ECU 4. The lock button 9 is a button that is pushed when the operator locks the unlocked door lock.

  The smart ECU 4 is connected to a door ECU 10 that controls locking and unlocking of the door lock through a bus 11. The door ECU 10 drives the door lock motor 12 based on a command from the smart ECU 4 to place the door lock in a locked state or an unlocked state.

  When the vehicle 1 is parked (engine stopped and door lock locked), the smart ECU 4 intermittently transmits a request signal Sreq in the LF band from the outside LF transmitter 5 to form a communication area around the door. When there are a plurality of out-of-vehicle LF transmitters 5 as in this example, the out-of-vehicle LF transmitters 5 transmit the request signal Sreq in order one by one and repeat this operation. When the portable device 3 enters this communication area and receives the request signal Sreq, the portable device 3 responds to the request signal Sreq and returns an ID signal Sid carrying its own ID code as an RF band signal. When the smart ECU 4 receives the request signal Sreq via the RF receiver 7, the smart ECU 4 compares the ID code registered in the self ECU 4 with the ID code of the portable device 3 and performs ID verification (external vehicle verification). When the vehicle exterior verification is established, the smart ECU 4 sets the vehicle exterior verification establishment flag in the internal memory to recognize the vehicle exterior verification, and activates the standby touch sensor 8.

  The smart ECU 4 outputs a door lock release request signal to the door ECU 10 when the touch sensor 8 detects a touch operation on the outside handle knob while the outside vehicle verification is established. Upon receiving the door lock release request signal, the door ECU 10 rotates the door lock motor 12 to one side to release the locked door lock. The smart ECU 4 that has output the door lock release request signal lowers the vehicle exterior verification establishment flag in the internal memory.

  The smart ECU 4 is connected to a power supply ECU 13 that manages the power supply of the on-vehicle electrical components and an engine ECU 15 that performs ignition control and fuel injection control of the engine 14 through the bus 11. Connected to the power supply ECU 13 are an on-vehicle accessory and a push switch 16 operated when operating the engine, an ACC relay 17 connected to the on-vehicle accessory, and an IG relay 18 connected to the engine ECU 15.

  When the smart ECU 4 detects that the door has been opened by, for example, a courtesy switch or the like after the vehicle outside verification is established and the door lock is released, the smart ECU 4 recognizes that the driver gets on the vehicle, and receives the request signal Sreq from the in-vehicle LF transmitter 6. To form a communication area in the car. When the smart ECU 4 receives the ID signal Sid returned from the portable device 3 entering the communication area by the RF receiver 7, the smart ECU 4 compares the ID code registered in the mobile device 3 with the ID code of the portable device 3 to verify the ID ( Car interior verification). When the in-vehicle collation is established, the smart ECU 4 sets an in-vehicle collation establishment flag in the internal memory and recognizes that the in-vehicle collation is established.

  When the rider pushes the push switch 16 while stepping on the brake pedal, the power supply ECU 13 that detects this operation confirms the in-vehicle collation result with the smart ECU 4. When the power supply ECU 13 receives notification from the smart ECU 4 that the indoor verification has been established, the power supply ECU 13 turns on the ACC relay 17 and the IG relay 18 and outputs an activation signal to the engine ECU 15. The engine ECU 15 that has received the start signal performs encrypted communication with the smart ECU 4 to confirm the in-vehicle verification result and to perform pairing to confirm that the communication destination is the smart ECU 4 that forms a pair. After confirming both of these conditions, the engine ECU 15 starts ignition control and fuel injection control to start the engine 14.

  Suppose the engine is stopped and the driver gets off. When the vehicle 1 is in a stopped state (engine stop and door unlock state), the smart ECU 4 detects that the lock button 9 has been pressed, and detects that the portable device 3 is left behind in the vehicle. The request signal Sreq is transmitted from 6 to perform in-vehicle collation. At this time, if the smart ECU 4 does not receive the ID signal Sid by the RF receiver 7, the smart ECU 4 recognizes that the portable device 3 has not been left behind in the vehicle.

  The smart ECU 4 recognizing that the portable device 3 has not been left in the vehicle causes the request signal Sreq to be transmitted from the LF transmitter 5 outside the vehicle. When there are a plurality of out-of-vehicle LF transmitters 5 as in this example, the out-of-vehicle LF transmitter 5 transmits the request signal Sreq in order one by one. When the smart ECU 4 receives this request signal Sreq and recognizes that collation outside the vehicle is established in the ID code returned from the portable device 3, the smart ECU 4 outputs a door lock locking request signal to the door ECU 10. Upon receiving the door lock locking request signal, the door ECU 10 rotates the door lock motor 12 to the other side to lock the door lock in the released state.

  As shown in FIG. 2, the vehicle exterior LF transmitter 5 is provided with a vehicle exterior antenna 21 including a series circuit of a coil 19 and a capacitor 20. A vehicle exterior antenna output adjustment resistor 22 that determines an antenna output (signal strength) of the vehicle exterior antenna 21 is connected in series to the vehicle exterior antenna 21. The vehicle exterior antenna 21 is connected to the smart ECU 4 via a vehicle exterior antenna drive circuit 23 composed of, for example, a full bridge or a half bridge. The antenna transmission frequency of the outside antenna 21 is set by the characteristic values of the coil 19 and the capacitor 20. The vehicle exterior antenna 21 constitutes an antenna (drive antenna, standby antenna) and an outdoor antenna, and the vehicle exterior antenna drive circuit 23 constitutes an antenna drive circuit.

  A first FET 24 made of an element such as a MOSFET is connected between the vehicle exterior antenna 21 and the vehicle exterior antenna drive circuit 23. The first FET 24 has a drain terminal connected to the capacitor 20 of the vehicle exterior antenna 21, a source terminal connected to the vehicle exterior antenna drive circuit 23, and a gate terminal connected to the smart ECU 4. The first FET 24 is switched on and off when the voltage applied to the gate terminal is controlled by the smart ECU 4. The first FET 24 constitutes a switching element.

Similarly, the in-vehicle LF transmitter 6 is provided with an in-vehicle antenna 27 composed of a series circuit of a coil 25 and a capacitor 26. An in-vehicle antenna output adjustment resistor 28 that determines the antenna output (signal strength) of the in-vehicle antenna 27 is connected in series to the in-vehicle antenna 27. The in-vehicle antenna 27 is connected to the smart ECU 4 via an in-vehicle antenna drive circuit 29 made of, for example, a full bridge or a half bridge. The antenna transmission frequency of the vehicle interior antenna 27 is set by the characteristic values of the coil 25 and the capacitor 26. Each communication area of the vehicle exterior LF transmitter 5 and the vehicle interior LF transmitter 6 is set so that the area ranges are different from each other due to usage conditions. Therefore, the vehicle exterior antenna output adjustment resistor 22 and the vehicle interior antenna output adjustment resistor 28 are appropriately set. Each area range is set by adjusting to a suitable value. The vehicle interior antenna 27 constitutes an antenna (drive antenna, standby antenna) and an indoor antenna, and the vehicle interior antenna drive circuit 29 constitutes an antenna drive circuit.
The vehicle exterior antenna drive circuit 23 is formed on the same printed circuit board as the vehicle interior antenna drive circuit 29, and shares the vehicle interior antenna drive circuit 29 and the power source Vcc. In addition, the harness of the vehicle exterior antenna circuit 30 including the vehicle exterior antenna 21, vehicle exterior antenna output adjustment resistor 22 and vehicle exterior antenna drive circuit 23, and vehicle interior antenna circuit 31 composed of vehicle interior antenna 27, vehicle interior antenna output adjustment resistor 28 and vehicle interior antenna drive circuit 29. The harness is in a position in which the vehicle runs in parallel in the assembled state of the vehicle body. The vehicle exterior antenna circuit 30 and the vehicle interior antenna circuit 31 constitute an antenna circuit.

  Between the vehicle interior antenna 27 and the vehicle interior antenna drive circuit 29, a second FET 32 made of an element such as a MOSFET is connected. The second FET 32 has a drain terminal connected to the capacitor 26 of the vehicle interior antenna 27, a source terminal connected to the vehicle interior antenna drive circuit 29, and a gate terminal connected to the smart ECU 4. Similarly to the first FET 24, the second FET 32 is switched on and off by controlling the voltage applied to its gate terminal by the smart ECU 4. The second FET 32 constitutes a switching element.

Next, the operation of the hands-free system 2 of this example will be described.
When the lock button 9 is pressed while the vehicle 1 is stopped, the smart ECU 4 issues an ID code return request command to cause the request signal Sreq to be transmitted from the in-vehicle antenna 27 in order to confirm that the portable device 3 has been left in the vehicle. A rectangular wave is output to the vehicle interior antenna drive circuit 29, and the antenna current Ia shown in FIG. At this time, the smart ECU 4 turns on the second FET 32 during the request signal transmission period and closes the vehicle interior antenna circuit 31 as shown in FIG. Thereby, the vehicle interior antenna 27 transmits the request signal Sreq shown in FIG. 3C according to the waveform of the antenna current Ia shown in FIG.

  Here, the portable device 3 that has received the request signal Sreq output from the in-vehicle LF transmitter 6 determines the threshold level Sx (see FIG. 3C or FIG. 4C) from the peak value Kmax of the waveform of the request signal Sreq. Then, the received request signal Sreq is demodulated, and converted to pulsed received data Da having a high level when the signal value exceeds the threshold level Sx and a low level when the signal value falls below the threshold level Sx. The threshold level Sx is set, for example, as a value of about 60 to 80% with respect to the peak value Kmax.

  When the portable device 3 is located in the in-vehicle communication area of the in-vehicle LF transmitter 6, the portable device 3 receives the request signal Sreq shown in FIG. 3C, and the portable device 3 that has received this request signal Sreq has an antenna The reception data Da shown in FIG. 3 (d), which is at a high level when the current Ia is flowing and is at a low level when the antenna current Ia is not flowing, is acquired. Since this received data Da is data that requests the portable device 3 to return an ID code, the portable device 3 that has received this received data Da puts its own ID code in response to the request signal Sreq. An ID signal Sid is returned.

  When the smart ECU 4 receives this ID signal Sid via the RF receiver 7, the smart ECU 4 compares the ID code of the portable device 3 with the ID code registered in the mobile phone 3 and performs in-vehicle collation. If the in-vehicle collation is established, it is recognized that the portable device 3 is left behind in the vehicle. The smart ECU 4 in this state does not allow the door to be locked even if the lock button 9 is pressed, and prevents the vehicle 1 from being locked.

  Here, when the antenna current Ia flows through the vehicle interior antenna circuit 31, a magnetic field is generated around the vehicle interior antenna circuit 31. By the way, in the hands-free system 2 of this example, the vehicle exterior antenna drive circuit 23 and the vehicle interior antenna drive circuit 29 are provided on the same printed circuit board, and the harness of the vehicle exterior antenna circuit 30 and the harness of the vehicle interior antenna circuit 31 are arranged in parallel. Running. For this reason, when a magnetic field is generated around the vehicle interior antenna circuit 31, a current is induced in the vehicle exterior antenna circuit 30 by this magnetic field, and the request signal Sreq is transmitted from the vehicle exterior LF transmitter 5.

  Therefore, for example, when the in-vehicle verification LF signal (that is, the request signal Sreq) leaks from the in-vehicle antenna 21 when the in-vehicle antenna 27 is transmitted and an in-vehicle communication area is formed around the out-of-vehicle antenna 21, the portable device 3 When is located, the portable device 3 receives the request signal Sreq for in-vehicle verification from the LF transmitter 5 outside the vehicle. In this case, the portable device 3 receives the request signal Sreq for in-vehicle collation from the outside LF transmitter 5 and returns the ID signal Sid even though the portable device 3 is outside the vehicle, and the position of the portable device 3 is erroneously determined. Will be. In this case, even if the driver is outside the vehicle and presses the lock button 9, the door cannot be locked.

  Therefore, in this example, when the request signal Sreq is transmitted to the vehicle interior antenna 27, the smart ECU 4 turns the first FET 24 on and off at least once during the request signal transmission period as shown in FIG. 4B. As a result, a wraparound / coupled current Ib as shown in FIG. 4A, which has a low current value when the first FET 24 is turned off, flows in the vehicle exterior antenna circuit 30. In the wrap-around / coupled current Ib, the current value increases when the first FET 24 is in the on state, which is induced by the wrap-around current that wraps around from the GND or the power source Vcc to the outside antenna circuit 30 and the magnetic field of the inside antenna circuit 31. The reason why the current value decreases when the first FET 24 is in the OFF state is that only the coupling current by the in-vehicle antenna circuit 31 flows.

  Therefore, the portable device 3 that has entered the communication area around the outside antenna 21 at the time of in-vehicle verification has a low signal peak value Kmax when the first FET 24 is turned off. LF shown in FIG. The signal Slf is received. When the portable device 3 receives the LF signal Slf, the threshold level Sx is set from the peak value of the LF signal Slf and the LF signal Slf is converted into a pulsed signal, so that the LF shown in FIG. When the signal Slf is received, the reception data Db shown in FIG. 4D, which is at the low level when the first FET 24 is turned off, is acquired.

  Here, the received data Db is not data indicating an ID reply, unlike the received data Da shown in FIG. Therefore, even when the portable device 3 is located outside the vehicle, even if it receives a leak signal for vehicle interior verification (ie, the LF signal Slf) from the vehicle exterior antenna 21, it does not receive a request signal indicating that an ID is returned. Communication between the portable device 3 and the in-vehicle LF transmitter 6 is not established, and an operation for returning the ID signal Sid in response to the request signal Sreq is not performed. For this reason, it is not necessary for the portable device 3 outside the vehicle to be in-vehicle collation, and erroneous determination is unlikely to occur when the position of the portable device 3 is determined.

  Although not described in detail, the same operation as in-vehicle verification is performed when performing external verification. That is, the smart ECU 4 when performing outside-vehicle verification outputs an ID code reply request command to the outside-antenna drive circuit 23 as a rectangular wave so that the request signal Sreq is transmitted from the outside-antenna 21, and the first FET 24 is turned on during this request signal transmission period. Turns on and closes the outside antenna circuit 30. At this time, the smart ECU 4 turns on and off the second FET 32 at least once in the request signal transmission period. This makes it difficult to make an erroneous determination when determining the position of the portable device 3 in the outside-vehicle verification.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) When the request signal Sreq is transmitted from the driven transmitter in the outside verification or in-vehicle verification, the transmitter-side FET that is not driven is turned on / off at least once in the request signal transmission period. As a result, even if a sneak current or coupling current flows through the transmitter that is not driven and an unintended LF signal is transmitted from the transmitter, it does not prompt the portable device 3 to return an ID code. Therefore, when the portable device 3 receives the LF signal from the transmitter that is not driven when performing the outside verification or the in-vehicle verification, the portable device 3 does not send back the ID signal Sid in response thereto. Communication between the mobile device 3 and the portable device 3 is not established, and it is difficult to erroneously determine the position of the portable device 3.

  (2) Since misjudgment is less likely to occur when determining whether the portable device 3 is outside or inside the vehicle, for example, an inlock that locks the door lock while leaving the portable device 3 in the vehicle, Even when the portable device 3 is outside the vehicle, a situation in which the door lock cannot be locked can be made difficult to occur.

(Second Embodiment)
Next, a second embodiment of the electronic key communication device and the electronic key communication system will be described with reference to FIGS. The second embodiment is different from the first embodiment only in that the transmission area of the signal transmitted from the non-driven antenna is reduced, and the other basic configuration is the same. Similar parts are denoted by the same reference numerals, detailed description thereof is omitted, and only different parts are described.

  As shown in FIG. 5, a series circuit of an antenna output attenuation resistor 41 and a third FET 42 is connected to the capacitor 20 of the vehicle exterior antenna 21 in parallel with the first FET 24. The antenna output attenuation resistor 41 and the third FET 42 are attached in the order of the antenna output attenuation resistor 41 and the third FET 42 from the outside antenna 21 side. The antenna output attenuation resistor 41 is such that the signal strength of the LF signal transmitted from the vehicle exterior antenna 21 when the vehicle exterior antenna 21 is not driven is greater than the signal strength of the request signal Sreq transmitted from the vehicle interior antenna 27 during vehicle interior verification in the vehicle communication area. The value is set to be low.

  The third FET 42 is composed of, for example, a MOSFET, and the drain terminal is connected to the vehicle exterior antenna 21 via the antenna output attenuation resistor 41, the source terminal is connected to the vehicle exterior antenna drive circuit 23, and the gate terminal is connected to the smart ECU 4. Has been. As with the first FET 24 and the second FET 32, the third FET 42 is switched on and off by the voltage applied to its gate terminal being controlled by the smart ECU 4. The antenna output attenuation resistor 41 corresponds to an antenna output adjustment element, and the third FET 42 corresponds to an antenna output adjustment switching element.

Next, the operation of the hands-free system 2 of this example will be described.
First, the smart ECU 4 outputs an ID code reply request command (drive command) to the vehicle exterior antenna drive circuit 23 as a rectangular wave so as to transmit the request signal Sreq from the vehicle exterior antenna 21 when performing vehicle exterior verification. In the period, the first FET 24 is turned on and the third FET 42 is kept off. As a result, a request signal Sreq that prompts the portable device 3 to return an ID code is transmitted from the vehicle exterior antenna 21 with a signal strength that conforms only to the vehicle exterior antenna output adjustment resistor 22.

  At this time, when the smart ECU 4 transmits the request signal Sreq from the antenna 21 outside the vehicle, the smart ECU 4 turns on and off the second FET 32 at least once in the request signal transmission period. As a result, the current value of the in-vehicle antenna circuit 31 becomes low when the second FET 32 is turned off, that is, a wraparound / coupled current having a current waveform different from that of the antenna current flowing through the outside antenna circuit 30 flows. Therefore, even if the portable device 3 receives the LF signal Slf transmitted from the in-vehicle LF transmitter 6 by this wraparound / coupled current, it is not a signal for requesting an ID code return, so the portable device 3 Even if the LF signal Slf is received from the LF transmitter 6, the operation of returning the ID signal Sid in response thereto is not performed.

  On the other hand, the smart ECU 4 outputs an ID code reply command request to the in-vehicle antenna drive circuit 29 as a rectangular wave so as to transmit the request signal Sreq from the in-vehicle antenna 27 when performing in-vehicle verification. 2 FET32 is turned on. At this time, the smart ECU 4 turns the third FET 42 on and off at least once while the first FET 24 remains off.

  At this time, a wraparound / coupled current flows through the vehicle exterior antenna circuit 30, but this wraparound / coupled current flows through the antenna circuit including the vehicle exterior antenna drive circuit 23, the vehicle exterior antenna 21, and the antenna output attenuation resistor 41. The wraparound / coupled current flowing at this time has a current value lower when the third FET 42 is turned off, that is, a current having a current waveform different from the current flowing in the vehicle interior antenna circuit 31 flows. Therefore, even if the portable device 3 receives the LF signal Slf transmitted from the outside LF transmitter 5 by this wraparound / coupled current, it is not a signal for requesting the ID code return. Even if the LF signal Slf is received from the LF transmitter 5, the operation of returning the ID signal Sid in response thereto is not performed.

  By the way, the vehicle exterior communication area of the vehicle exterior LF transmitter 5 inevitably enters the vehicle communication area formed by the vehicle interior LF transmitter 6 due to the arrangement position. At this time, for example, if the portable device 3 is positioned at the door portion (for example, a pocket on the inner side surface of the door) in the vehicle interior verification, the LF signal Slf of the vehicle exterior LF transmitter 5 and the vehicle interior LF transmitter 6 The portable device 3 may receive a signal superimposed with the request signal Sreq.

  At this time, for example, as shown by the solid line in FIG. 6A, when the signal transmission strength of the vehicle exterior LF transmitter 5 is stronger than that of the vehicle interior LF transmitter 6, the vehicle LF signal Slf on the vehicle exterior LF transmitter 5 side is When superimposed on the request signal Sreq on the LF transmitter 6 side, the superimposed signal Smix is shifted to the LF signal Slf on the outside LF transmitter 5 side as shown by the broken line in FIG. That is, the superposition signal Smix occupies a large amount of the signal component of the LF signal Slf due to the wraparound / coupling current, and as a result, becomes a signal that is close to the LF signal Slf due to the wrapping / coupling current. Therefore, under this situation, although the portable device 3 is in the room, the mobile device 3 cannot receive the request signal Sreq from the in-vehicle LF transmitter 6 and return the ID signal Sid, and erroneously determines the position. Occurs.

  However, in this example, when the in-vehicle verification is performed, the LF signal Slf transmitted from the external LF transmitter 5 by the wraparound / coupled current is transmitted with a signal intensity according to the antenna output attenuation resistor 41. That is, the LF signal Slf transmitted from the LF transmitter 5 by the wraparound / coupled current is transmitted in a narrow communication area, that is, a signal having a weak signal strength.

  Therefore, even if the portable device 3 is located at the inner side of the door and receives a signal in which the LF signal Slf of the outside LF transmitter 5 and the request signal Sreq of the in-vehicle LF transmitter 6 are superimposed, the superimposed signal Smix As shown in FIG. 6B, the request signal Sreq on the in-vehicle LF transmitter 6 side occupies a large amount of signal components, and as a result, the request signal Sreq of the in-vehicle LF transmitter 6 becomes a signal. Therefore, even if the portable device 3 is inside the door, the portable device 3 takes an operation of receiving the request signal Sreq from the in-vehicle LF transmitter 6 and returning the ID signal Sid. Effective in prevention.

According to the configuration of the present embodiment, in addition to the effects (1) and (2) described in the first embodiment, the following effects can be obtained.
(3) When performing in-vehicle collation, the communication area of the LF signal Slf transmitted from the outside LF transmitter 5 by the wraparound / coupled current is the request signal Sreq transmitted from the out-of-vehicle LF transmitter 5 when performing out-of-vehicle verification. The area range is smaller than that. Therefore, when the in-vehicle collation is performed, it is difficult to establish a situation in which communication is not established between the portable device 3 and the in-vehicle LF transmitter 6 even though the portable device 3 is in the vehicle. The effect of preventing erroneous determination during position determination is enhanced.

In addition, this embodiment is not limited to the said structure, For example, you may change to the following aspects.
In the first and second embodiments, the hands-free system 2 does not necessarily have both functions of door lock locking / unlocking permission and engine start permission, but either one of these two functions. Just have it.

  In the first and second embodiments, when the engine 14 is permitted to start, the engine 14 is not limited only to the collation of the ID code of the portable device 3. For example, a transponder is attached to the portable device 3 and an immobilizer using the transponder is used. The establishment of verification may be added to the conditions for starting the engine.

  In the first and second embodiments, when the request signal Sreq is transmitted from the transmitter on the driving side, the number of times the transmitter-side FET that is not driven is turned on / off in the request signal transmission period is not necessarily limited to one. It may be twice or more.

  -In 1st and 2nd embodiment, if the switching element provided in the vehicle exterior LF transmitter 5 and the vehicle interior LF transmitter 6 is not restricted to MOSFET but each antenna circuit 30 and 31 can be turned on and off, the element is There is no particular limitation.

  In the second embodiment, the series circuit composed of the antenna output attenuation resistor 41 and the third FET 42 is not limited to being provided on the outside LF transmitter 5, but on the inside LF transmitter 6 side instead of the outside LF transmitter 5 side. It may be provided.

  In the first and second embodiments, the process performed when the portable device 3 receives the request signal Sreq is a process of setting the threshold level from the peak value Kmax of the request signal Sreq and converting the request signal Sreq into a pulse signal. Not limited to this, any other process may be adopted.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) In Claims 1 to 4, when the electronic key receives a transmission signal transmitted from the antenna, the electronic key sets a threshold value from the peak value of the transmission signal, and the transmission signal is set with reference to the threshold value. It is converted into a pulse signal and acquired as received data. In this case, the electronic key that has received the transmission signal acquires the data converted into a pulse signal as reception data, and executes processing based on the reception data.

The block diagram which shows the structure of the hands-free system in 1st Embodiment. The circuit diagram which shows the structure of an external LF transmitter and an in-vehicle LF transmitter. It is various waveforms which flow at the time of in-vehicle collation, (a) is an antenna current waveform diagram which flows into an in-vehicle LF transmitter, (b) is a switch waveform diagram of the 2nd FET provided in the in-vehicle LF transmitter, (c) is in-vehicle LF transmission The wave form diagram of the request signal which a machine transmits, (d) is the wave form figure of the reception data which a portable machine receives at that time. It is various waveforms which flow at the time of in-vehicle collation, (a) is an antenna current waveform diagram which flows into an LF transmitter outside a vehicle, (b) is a switch waveform diagram of the 1st FET provided in an LF transmitter outside a vehicle, (c) is LF transmission outside a vehicle The wave form diagram of the request signal which a machine transmits, (d) is the wave form figure of the reception data which a portable machine receives at that time. The circuit diagram which shows the structure of the in-vehicle LF transmitter and the in-vehicle LF transmitter in 2nd Embodiment. It is a signal waveform diagram when the LF signal of the LF transmitter outside the vehicle and the request signal of the LF transmitter inside the vehicle are superimposed, (a) is a waveform diagram when the signal strength of the LF signal is strong, (b) is the LF signal The waveform diagram when the signal strength is weak. The circuit diagram which shows the structure of the conventional LF transmitter outside a vehicle and LF transmitter in a vehicle. It is various waveform diagrams which flow at the time of in-vehicle collation, (a) is an antenna current waveform diagram which flows into an in-vehicle LF transmitter, (b) is a switch waveform diagram of the second FET provided in the in-vehicle LF transmitter, (c) is portable at that time FIG. 4 is a waveform diagram of received data received by the machine. It is various waveform diagrams which flow at the time of in-vehicle collation, (a) is an antenna current waveform diagram which flows into the LF transmitter outside the vehicle, (b) is a switch waveform diagram of the first FET provided in the LF transmitter outside the vehicle, (c) is portable at that time FIG. 4 is a waveform diagram of received data received by the machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Portable machine as an electronic key, 4 ... Mart ECU which comprises a communication control circuit and a control means, 21 ... Antenna (driving antenna, standby antenna) and the outdoor antenna which comprises an outdoor antenna, 23 ... The antenna drive circuit is comprised Outside antenna drive circuit, 24 ... first FET constituting switching element, 27 ... antenna (drive antenna, standby antenna) and in-vehicle antenna constituting indoor antenna, 29 ... in-vehicle antenna drive circuit constituting antenna drive circuit, 30 ... antenna In-vehicle antenna circuit constituting circuit, 31 .. In-car antenna circuit constituting antenna circuit, 32... Second FET constituting switching element, 41 .. antenna output attenuation resistor as antenna output adjustment element, 42 .. antenna output adjustment switching element 3rd FET, Sreq ... Request signal, Da, Db ... receiving data of Te.

Claims (6)

A plurality of antenna drive circuits provided in each of a plurality of antennas;
A plurality of switching elements provided for each of the antenna drive circuits to turn on and off energization of each antenna circuit of the antenna;
A drive control circuit for controlling the antenna via the antenna drive circuit, and a communication control circuit for controlling on / off of the switching element,
In the electronic key communication device in which when the electronic key receives a transmission signal transmitted from the antenna, the electronic key acquires the transmission signal as reception data.
When transmitting the transmission signal from the antenna to be driven among the plurality of antennas, the driving command is sent to the antenna driving circuit on the driving antenna side and the switching element on the driving antenna side is turned on in the signal transmission period, The standby antenna that is not driven includes a control unit that turns on and off the switching element of the standby antenna at least once in the signal transmission period ,
The drive antenna is one of an outdoor antenna installed outside the room to be entered / exited and an indoor antenna installed in the room to be entered / exited, and the standby antenna is the outdoor antenna and the room An electronic key communication device which is the other of the antennas . A plurality of antenna drive circuits provided in each of a plurality of antennas;
A plurality of switching elements provided for each of the antenna drive circuits to turn on and off energization of each antenna circuit of the antenna;
A drive control circuit for controlling the antenna via the antenna drive circuit, and a communication control circuit for controlling on / off of the switching element,
In the electronic key communication device in which when the electronic key receives a transmission signal transmitted from the antenna, the electronic key acquires the transmission signal as reception data.
An antenna output adjusting element for attenuating an antenna output connected to at least one of the switching elements in parallel with the switching element;
An antenna output adjustment switching element connected in series to the antenna output adjustment element;
When transmitting the transmission signal using the antenna to which the antenna output adjustment element is not connected among the plurality of antennas as a drive antenna, a drive command is sent to the antenna drive circuit on the drive antenna side and the drive antenna side For the standby antenna that is turned on in the signal transmission period and is not driven and connected to the antenna output adjustment element, the switching element of the standby antenna is turned off, and the antenna output adjustment switching element is An electronic key communication device comprising: a control means for turning on and off at least once during a transmission period. The drive antenna is one of an outdoor antenna installed outside the room to be entered / exited and an indoor antenna installed in the room to be entered / exited, and the standby antenna is the outdoor antenna and the room The electronic key communication device according to claim 2 , wherein the electronic key communication device is the other of the antennas.   The drive antenna is one of an outdoor antenna installed outside the room to be entered / exited and an indoor antenna installed in the room to be entered / exited, and the standby antenna is the outdoor antenna and the room The series circuit including the antenna output adjustment element and the antenna output adjustment switching element, which is the other of the antennas, is connected in parallel to the switching element of the outdoor antenna. The electronic key communication apparatus described in 1. A plurality of antenna drive circuits provided in each of a plurality of antennas, a plurality of switching elements provided for each of the antenna drive circuits to turn on and off the power of each antenna circuit of the antenna, and the antenna drive circuit through the antenna drive circuit A communication unit having a communication control circuit for driving and controlling the antenna and performing on / off control of the switching element;
In an electronic key communication system comprising an electronic key for acquiring the transmission signal as reception data when the transmission signal transmitted by the antenna is received,
The communication unit is
When transmitting the transmission signal from the antenna to be driven among the plurality of antennas, the driving command is sent to the antenna driving circuit on the driving antenna side and the switching element on the driving antenna side is turned on in the signal transmission period, The standby antenna that is not driven includes a control unit that turns on and off the switching element of the standby antenna at least once in the signal transmission period ,
The drive antenna is one of an outdoor antenna installed outside the room to be entered / exited and an indoor antenna installed in the room to be entered / exited, and the standby antenna is the outdoor antenna and the room An electronic key communication system which is the other of the antennas . A plurality of antenna drive circuits provided in each of a plurality of antennas, a plurality of switching elements provided for each of the antenna drive circuits to turn on and off the power of each antenna circuit of the antenna, and the antenna drive circuit through the antenna drive circuit A communication unit having a communication control circuit for driving and controlling the antenna and performing on / off control of the switching element;
In an electronic key communication system comprising an electronic key for acquiring the transmission signal as reception data when the transmission signal transmitted by the antenna is received,
The communication unit is
An antenna output adjusting element for reducing antenna output attenuation connected to at least one of the switching elements in parallel with the switching element;
An antenna output adjustment switching element connected in series to the antenna output adjustment element;
When transmitting the transmission signal using the antenna to which the antenna output adjustment element is not connected among the plurality of antennas as a drive antenna, a drive command is sent to the antenna drive circuit on the drive antenna side and the drive antenna side For the standby antenna that is turned on in the signal transmission period and is not driven and connected to the antenna output adjustment element, the switching element of the standby antenna is turned off, and the antenna output adjustment switching element is An electronic key communication system comprising control means for turning on and off at least once during a transmission period.

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