JP2009030337A - Smart keyless entry system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a user to receive a radio signal of a portable machine securely. <P>SOLUTION: The smart keyless entry system is composed of an on-board machine 100 loaded on a vehicle and the portable machine 200 carried by an occupant to control on-vehicle control equipments 50, 52, 54 by receiving the radio signals from the portable machine 200 by the on-vehicle machine 100. The on-board machine 100 has a receiving antenna 1042 for receiving the radio signals from the portable machine 200, a receiving circuit 1044 for demodulating the radio signals received by the receiving antenna 1042 into electric signals, a matching circuit 1046 for matching impedance of the receiving antenna 1042 and impedance of the receiving circuit 1044 mutually, a voltage detecting means 1048 for detecting the electric signal demodulated by the receiving circuit 1044, and a matching optimizing means 1050 for optimizing mutual matching of impedance of the receiving antenna 1042 and impedance of the receiving circuit 1044 by controlling the matching circuit 1046 based on the voltages detected by the voltage detecting means 1048. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a smart keyless entry system that locks / unlocks a vehicle door or permits engine start without using a key, and belongs to the technical field of wireless communication in the smart keyless entry system.

  2. Description of the Related Art Conventionally, there is a control system that locks or unlocks a door of a vehicle based on a signal from a portable device carried by an occupant, or permits an engine to start (see, for example, Patent Document 1). In this system, it is possible to perform the same operation as a conventional key only by carrying the portable device without performing a manual operation like a conventional key. This system is therefore called a smart keyless entry system.

  The smart keyless entry system is composed of an in-vehicle device mounted on a vehicle and a portable device carried by an occupant, and by performing wireless communication between them, the in-vehicle device locks or unlocks the door of the vehicle, Or control which permits starting of an engine is performed. For example, when an occupant carrying a portable device gets on, the engine is permitted to start.

  In such a smart keyless system, the receiving device of the in-vehicle device that receives a radio signal from the portable device is disposed in the passenger compartment near the driver's seat where the passenger is likely to carry the portable device, that is, the driver. . Thereby, the wireless communication between the portable device and the in-vehicle device is reliably executed.

JP 2006-104664 A

  However, the receiving sensitivity of the receiving device of the vehicle-mounted device changes depending on the change in the state of the vehicle interior. For example, the position changes depending on the position of the driver's seat, the angle of the seat back, movement of passengers other than the driver, luggage, and the open / close state of the movable roof and window. In particular, it is easy to change when moving on-vehicle equipment having a metal body. As a result, wireless communication may not be performed favorably between the portable device and the in-vehicle device.

  In addition, the state of the vehicle interior varies from vehicle type to vehicle type. For example, the size of the vehicle room and the number of seats differ from vehicle type to vehicle type. Don't be. In other words, the in-vehicle device of the smart keyless entry system cannot be shared. As a result, the total production cost of vehicles of a plurality of vehicle types increases.

  Therefore, the present invention can be used in common for vehicles having different vehicle interior conditions, that is, different vehicle types, while performing wireless communication well between the portable device and the vehicle-mounted device even when the vehicle interior conditions change. It is an object of the present invention to provide a smart keyless entry system that can be used.

  In order to solve the above-mentioned problem, the invention according to claim 1 of the present application includes an in-vehicle device mounted on a vehicle and a portable device carried by an occupant, and the in-vehicle device transmits a radio signal from the portable device. A smart keyless entry system for receiving and controlling a vehicle-mounted control device, wherein the vehicle-mounted device demodulates a reception antenna that receives a radio signal from the portable device and a radio signal received by the reception antenna into an electric signal Based on a reception circuit, a matching circuit that performs impedance matching between the reception antenna and the reception circuit, voltage detection means that detects a voltage of an electrical signal demodulated by the reception circuit, and voltage detected by the voltage detection means Matching optimization means for controlling the matching circuit to optimize impedance matching between the receiving antenna and the receiving circuit is provided.

  According to a second aspect of the present invention, in the smart keyless entry system according to the first aspect, the matching circuit includes a coil provided between the reception antenna and the reception circuit, and one end of the coil and the coil. The matching optimizing unit controls the capacitance of the capacitor. The variable capacity capacitor is connected between the receiving circuits and has the other end grounded.

  Further, the invention described in claim 3 is the smart keyless entry system described in claim 1 or 2, further comprising equipment movement detection means for detecting that the equipment of the vehicle has moved, and the matching optimization means. Is characterized in that when the equipment movement detecting means detects movement of equipment, the matching circuit is controlled to optimize impedance matching between the receiving antenna and the receiving circuit.

  Furthermore, the invention according to claim 4 is the smart keyless entry system according to any one of claims 1 to 3, wherein the equipment of the vehicle is at least one of a steering, a seat, or a movable roof. Characterized by

  In addition, according to a fifth aspect of the present invention, in the smart keyless entry system according to any one of the first to fourth aspects, the matching optimization unit optimizes impedance matching between the reception antenna and the reception circuit. In this case, the portable device has a wireless signal transmission execution means for transmitting a wireless signal to the receiving antenna.

  In addition, according to a sixth aspect of the present invention, in the smart keyless entry system according to any one of the first to fifth aspects, the matching optimization unit is configured to optimize impedance matching between the receiving antenna and the receiving circuit. Is performed while the vehicle is running.

  According to the first aspect of the present invention, the receiving sensitivity of the receiving circuit (receiving antenna) that has changed due to a change in the state of the passenger compartment is detected based on the voltage of the electrical signal demodulated from the radio signal by the receiving circuit, The matching circuit is controlled based on the voltage (reception sensitivity), and the impedance matching between the receiving antenna and the receiving circuit is optimized after the vehicle interior changes. As a result, the reception sensitivity deteriorated due to the change in the state of the vehicle interior is improved, and good wireless communication can be performed between the portable device and the vehicle-mounted device.

  From another viewpoint, it can be said that the reception sensitivity can be well adjusted even in vehicles having different vehicle interior conditions, that is, different vehicle types. Therefore, a common smart keyless entry system can be installed in each vehicle of different vehicle types.

  According to the second aspect of the present invention, the matching circuit includes a coil provided between the receiving antenna and the receiving circuit, and a capacitor having one end connected between the coil and the receiving circuit and the other end grounded. The impedance matching between the receiving antenna and the receiving circuit can be optimized by comprising a variable capacitor and the matching optimization means controlling the capacitance of the capacitor.

  According to the third aspect of the present invention, the change in the state of the passenger compartment is detected by the equipment movement detection means for detecting that the equipment of the vehicle has moved. Thereby, the matching optimization means can know that the state of the vehicle interior has changed, which is the timing at which the impedance matching between the receiving antenna and the receiving circuit needs to be optimized.

  Furthermore, according to the invention described in claim 4, the movement detection target of the equipment movement detection means for knowing the change in the state of the vehicle is at least one of a steering, a seat, or a movable roof. These are moved at an arbitrary timing by the occupant and greatly change the receiving sensitivity of the receiving circuit (receiving antenna). Therefore, by detecting the movement of at least one of the steering, the seat, or the movable roof, and after the detection timing, the matching optimization means optimizes the impedance matching between the receiving antenna and the receiving circuit, thereby the steering, the seat, or the movable Even if at least one of the roofs is moved at an arbitrary timing, the reception sensitivity is well adjusted and good wireless communication between the portable device and the in-vehicle device is realized.

  In addition, according to the invention described in claim 5, when the matching optimization unit optimizes impedance matching between the receiving antenna and the receiving circuit, the portable device transmits a radio signal to the receiving antenna (receiving antenna). To receive radio signals.) This realizes that the matching optimization means optimizes impedance matching between the receiving antenna and the receiving circuit.

  In addition, according to the sixth aspect of the invention, the matching optimization means optimizes impedance matching between the receiving antenna and the receiving circuit while the vehicle is running. This is because it is highly likely that the portable device is kept stationary at any position in the passenger compartment while the vehicle is running, for example, in the driver's pocket, in other words, between the receiving antenna and the portable device. This is because the distance is maintained substantially constant. Since the distance between the receiving antenna and the portable device is maintained substantially constant, the receiving antenna can stably receive a radio signal from the portable device, so the matching optimization means that the receiving antenna receives the wireless signal in an unstable manner. Compared with the case where it is, it becomes easy to optimize the impedance matching of a receiving antenna and a receiving circuit.

  FIG. 1 shows a vehicle equipped with a smart keyless entry system according to an embodiment of the present invention and a portable device of the system. FIG. 2 shows the configuration of the smart keyless entry system.

  As shown in FIG. 2, the smart keyless entry system includes an in-vehicle device 100 mounted on the vehicle 10 shown in FIG. 1 and a portable device 200 carried by a passenger.

  The in-vehicle device 100 includes a plurality of LF transmission antennas 102a to 102e for transmitting signals to the portable device 200, a UHF receiver 104 for receiving signals from the portable device 200, and a plurality of LF transmission antennas 102a to 102e. And a control device 106 that controls a control device mounted on the vehicle 10 based on a signal received by the UHF receiver 104.

  Each of the plurality of LF transmission antennas 102a to 102e is disposed at a predetermined position of the vehicle 10 as shown in FIG. The LF transmitting antenna 102a is located in the front door 14 on the passenger seat 12, the door 102b is located in the rear door 16, 102c is located in the door 18 on the driver's seat, 102d is located in front of the passenger seat 12, and 102e is located in the passenger compartment. It is disposed under the central rear seat 20.

  Each of the plurality of LF transmitting antennas 102a to 102e is controlled by the control device 106 to form an LF band magnetic field corresponding to a signal transmitted around it, and as shown in FIG. By detecting the LF band magnetic field formed in the detection circuit and receiving the above signal (magnetic field signal) based on the detected magnetic field, short-range communication (magnetic field communication) from the antenna to the portable device is executed. It is configured. Since the communication uses the magnetic field of the LF band, the transmission range (communication possible range) of the LF transmission antennas 102a to 102e is small as shown in FIG. The LF transmission antenna 102a has a transmission range A1 on the outside of the passenger door 14; 102b has a transmission range A2 on the outside of the rear door 16; 102c has a transmission range A3 on the outside of the driver side door 18; Is the transmission range A4, and 102e is the transmission range A5 on the rear side of the passenger compartment.

  Returning to FIG. 1, the UHF receiver 104 is disposed in front of the driver's seat. Further, as shown in FIG. 2, the UHF receiver 104 receives a UHF band radio signal from a UHF transmission antenna of the portable device 200 to be described later, and transmits a signal corresponding to the received radio signal to the control device 106. It is configured to output to. Details of the UHF receiver 104, which is a feature of the present invention, will be described later.

  The control device 106 is configured to control in-vehicle control devices such as a door lock actuator 50, an engine control unit (ECU) 52, and an alarm device 54 mounted on the vehicle 10 based on a signal from the UHF receiver 104. Has been. The door lock actuator 50 is provided in each of the passenger seat side door 14, the rear door 16, the driver seat side door 18, and the rear seat door, and locks or unlocks these doors. The ECU 52 is for controlling the engine, and the control device 106 is configured to allow the ECU 52 to start the engine. The engine is started when the control device 106 permits the ECU 52 to start the engine and then an ignition knob switch (not shown) is turned on by the occupant. Further, the alarm device 54 warns when the portable device 200 is taken out of the vehicle interior during driving. Details of the control executed by the control device 106 for these control devices will be described later.

  On the other hand, the portable device 200 has a card size that is portable as shown in FIG. 1, and receives a signal from any of the plurality of LF transmission antennas 102a to 102e of the in-vehicle device 100 as shown in FIG. A magnetic field detection circuit 202 for receiving, a lock switch 204 a for locking a door by an occupant outside the vehicle, an unlock switch 204 b for unlocking the door, and the UHF receiver 104 of the in-vehicle device 100 via the UHF transmission antenna 206. A UHF transmission circuit 208 for transmitting a radio signal in the UHF band and a control device 210 that controls the UHF transmission circuit 208 to transmit various signals.

  When the portable device 200 exists in the transmission range of any of the plurality of LF transmission antennas 102a to 102e of the in-vehicle device 100 and the LF transmission antenna in the transmission range outputs a magnetic field signal, the magnetic field detection circuit 202 outputs the magnetic field. It is configured to receive a signal. Further, the control unit 210 is configured to output a signal corresponding to the received magnetic field signal.

  As shown in FIG. 1, the lock switch 204 a and the unlock switch 204 b are button-like operation switches that the occupant presses, and are provided in the portable device 100. When the occupant performs an operation of pressing, the lock switch 204a and the unlock switch 204b are configured to output a signal indicating that the operation has been performed to the control device 210.

  The UHF transmission circuit 208 is configured to be able to transmit various signals via the UHF transmission antenna 206 under the control of the control device 210. The transmission from the in-vehicle device 100 to the portable device 200 is a magnetic field signal, whereas the reason for using the UHF band radio signal for the transmission from the portable device 200 to the in-vehicle device 100 is the UHF built in the portable device 200. This is because the transmission antenna 206 can be reduced in size, that is, the portable device 200 can be reduced in a card shape.

  The control device 210 is configured to control the UHF transmission circuit 208 based on signals from the magnetic field detection circuit 202, the lock switch 204a, and the unlock switch 204b. Details of the control will be described later.

  From here, the details of each component of the smart keyless entry system will be described while explaining the operation of the smart keyless entry system, that is, the operations of the in-vehicle device 100 and the portable device 200.

  First, when an occupant carrying the portable device 200 operates the lock switch 204a or the unlock switch 204b to unlock the door to get on the vehicle 10 or to get off and lock the door (that is, outside the vehicle compartment) The control device 210 of the portable device 200 causes the UHF transmission circuit 208 to transmit a signal.

  When the UHF receiver 104 of the in-vehicle device 100 receives the lock signal for locking the door or the unlock signal for unlocking, the control device 106 of the in-vehicle device 100 receives the request signal from the plurality of LF transmission antennas 102a to 102e. Send through each.

  At this time, when the portable device 200 exists in any one of the transmission ranges of the LF transmission antennas 102a to 102e, the magnetic field detection circuit 202 of the portable device 200 receives a request signal from the antenna in the transmission range where the portable device 200 exists. .

  Then, the portable device 200 transmits an ID signal (a signal indicating the ID of the portable device 200) by controlling the UHF transmission circuit 208.

  When the UHF receiver 104 of the in-vehicle device 100 receives the ID signal, the control device 106 of the in-vehicle device 100 performs ID authentication based on the received ID signal. When the ID authentication is established, the control device 106 controls the lock actuator 50 to unlock or lock the vehicle door.

  On the other hand, when the ID authentication is not established, or when the UHF receiver 104 cannot receive the ID signal within a predetermined time after transmitting the request signal, the control device 106 performs control to lock or unlock the door. Do not execute (time out).

  Next, when the occupant gets on the vehicle 10 (for example, when the door opening / closing sensor detects that the door is opened and closed again after the door is unlocked by the portable device 200), the control device of the in-vehicle device 100 106 confirms that the portable device 200 exists in the vehicle interior in order to allow the ECU 52 to start the engine. That is, it is confirmed whether or not an occupant carrying the portable device 200 is on board.

  Specifically, the control device 106 of the in-vehicle device 100 transmits a request signal for confirming that the portable device 200 exists in the passenger compartment from the transmission antennas 102d and 102e for the passenger compartment, and receives the request signal. The portable device 200 transmits an ID signal, and the in-vehicle device 100 confirms that the portable device 200 exists in the vehicle interior when ID authentication is established based on the received ID signal.

  When it is confirmed that the portable device 200 exists in the vehicle interior of the vehicle 10, the control device 106 of the in-vehicle device 100 permits the ECU 52 to start the engine. In this state, when an occupant turns on an ignition switch (not shown), the ECU 52 starts the engine.

  In addition, confirmation that the portable device 200 is present in the vehicle interior of the vehicle 10 is performed after it is confirmed that the portable device 200 exists once in the vehicle interior until the door is opened (the door is opened and the portable device 200 is carried). Until the occupant gets off). This is because, for example, there is a possibility that the vehicle 10 stops and the glass window of the door is opened despite the driving, and the portable device 200 is taken out of the passenger compartment together with the luggage through the window glass. . If the portable device 200 is taken out of the passenger compartment, the engine may not be restarted when returning from the stopped state.

  In order to deal with this, until it is confirmed that the portable device 200 exists in the vehicle interior and the door is opened, the control device 106 of the in-vehicle device 100 periodically confirms that the portable device 200 exists in the vehicle interior. If it is not confirmed, the alarm device 54 is controlled to give an alarm.

  From here, the detail of the UHF receiver 104 of the vehicle equipment 100 which is the characteristic part of this invention is demonstrated.

  The UHF receiver 104 is configured to adjust the reception sensitivity so that the radio signal from the portable device 200 can be satisfactorily received.

  For this purpose, as shown in FIG. 4, the UHF receiver 104 includes a reception antenna 1042 that receives a radio signal from the portable device 200, a reception circuit 1044 that demodulates the radio signal received by the reception antenna 1042, and A matching circuit 1046 that performs impedance matching between the reception antenna 1042 and the reception circuit 1044, a voltage detection unit 1048 that detects a voltage of an electrical signal demodulated by the reception circuit 1044, and a matching circuit based on the voltage detected by the voltage detection unit 1048 A matching optimization unit 1050 that optimizes impedance matching between the reception antenna 1042 and the reception circuit 1044 by controlling 1046 is provided.

  The reception antenna 1042 is for receiving a radio signal from the UHF transmission antenna 206 of the portable device 200.

  The receiving circuit 1044 is for demodulating various wireless signals received by the receiving antenna 1042 into electrical signals such as corresponding voltages and currents. For example, the receiving circuit 1044 receives a wireless signal indicating an ID signal transmitted from the portable device 200. It demodulates to the corresponding electric signal and outputs it to the control device 106 of the in-vehicle device 100. The control device 106 performs ID authentication based on the electrical signal from the receiving circuit 1044.

  The matching circuit 1046 is for making the impedance of the reception antenna 1042 and the impedance of the reception circuit 1044 equal or close to each other, that is, for impedance matching between the reception antenna 1042 and the reception circuit 1044. Arranged between the antenna 1042 and the receiving circuit 1044.

  The matching circuit 1046 includes a coil 1052 provided between the receiving antenna 1042 and the receiving circuit 1044, and a variable capacitance capacitor 1054 having one end connected between the coil 1052 and the receiving circuit 1044 and the other end grounded. Has been. By controlling the capacitance of the capacitor 1054, the impedance of the reception antenna 1042 and the impedance of the reception circuit 1044 are made equal to or close to each other, that is, impedance matching between the reception antenna 1042 and the reception circuit 1044 is performed.

  The voltage detector 1048 is for detecting the voltage of the electrical signal demodulated by the receiving circuit 1044. In other words, as will be described later, it is for detecting reception sensitivity.

  The matching optimization unit 1050 controls the matching circuit 1046, specifically, controls the capacitance of the capacitor 1054 of the matching circuit 1046 so that the impedance of the reception antenna 1042 and the impedance of the reception circuit 1044 are as equal as possible. In other words, it is for optimizing the impedance matching, and thereby adjusting the reception sensitivity of the UHF receiver 104 (reception circuit 1044) satisfactorily.

  Specifically, the matching optimization unit 1050 controls the capacitance of the capacitor 1054 while monitoring the voltage value detected by the voltage detection unit 1048. When the radio signal received by the reception antenna 1042 is stable and constant, the reception sensitivity of the UHF receiver 104 can be known from the voltage of the electrical signal demodulated by the reception circuit 1046, that is, the voltage detected by the voltage detection unit 1048. . If this voltage is high, the reception sensitivity is good, and if it is low, the reception sensitivity is not good. Therefore, the matching optimization unit 1050 monitors the voltage detected by the voltage detection unit 1048 while changing the capacitance of the capacitor 1054 within a controllable range, finds the capacitance value at which the voltage becomes maximum, and sets the capacitor value to the found capacitance value. By controlling 1054, the reception sensitivity of the UHF receiver 104 is adjusted well.

  In addition, the matching optimization unit 1050 controls the matching circuit 1046 (capacitor 1054) to satisfactorily adjust the reception sensitivity of the UHF receiver 104, when a change in the vehicle interior state that changes the reception sensitivity occurs. Is configured to run on.

  The reception sensitivity of the UHF receiver 104 depends on the changes in the vehicle interior, such as the position of the driver's seat, the angle of the seat back, the steering, the open / close state of the movable roof and the glass window, etc. Changes with movement. The alignment optimization unit 1050 detects that the state of the vehicle interior has changed by detecting movement of the seat, steering, movable roof, and window.

  More specifically, as shown in FIGS. 2 and 4, a change in the state of the passenger compartment is detected based on a signal from the sensor 56 that detects that the equipment has moved. The equipment movement sensor 56 corresponds to a sensor (seat position sensor) that detects the position of the seat in the case of a seat, and corresponds to a steering angle sensor in the case of steering. In the case of a movable roof or window, when the open / close switch is pushed by the occupant, it can be considered that the movable roof or window has moved (the switch serves as an equipment movement sensor). The “equipment movement sensor” is not limited to a seat, a steering wheel, a movable roof, a window, or the like, and refers to a sensor that detects movement of equipment that affects the reception sensitivity of the UHF receiver 104 when it moves.

  On the other hand, the reception sensitivity of the UHF receiver 104 also changes for reasons other than the equipment for which the equipment movement sensor 56 detects movement. For example, it changes due to movement of luggage or passengers, movement of equipment other than equipment whose movement is detected by the equipment movement sensor 56, and the like. Since such a change in the vehicle interior cannot be detected by a sensor as in the above-described equipment, the matching optimization unit 1050 periodically controls the matching circuit 1046 (capacitor 1054) to receive the receiving antenna 1042. And the impedance matching of the receiving circuit 1044 are optimized. Note that the reception sensitivity of the UHF receiver 104 does not change if the vehicle interior is the same before and after the impedance matching is optimized.

  Furthermore, the matching optimization unit 1050 sends a radio signal to the portable device 200 in order to satisfactorily adjust the reception sensitivity of the UHF receiver 104 (to optimize impedance matching between the receiving antenna 1042 and the receiving circuit 1044). It is configured to transmit to the reception antenna 1042 (functions as “radio signal transmission execution means” described in claims). This is because the matching optimization unit 1050 optimizes impedance matching based on the voltage of the electrical signal demodulated from the radio signal by the receiving circuit 1044 (that is, the receiving antenna 1042 receives the radio signal as described above). Otherwise, impedance matching optimization cannot be performed.)

  Specifically, as shown in FIGS. 2 and 4, when the matching optimization unit 1050 adjusts the reception sensitivity of the UHF receiver 104 satisfactorily, the portable device 200 is connected to the control device 106 of the in-vehicle device 100. A transmission instruction signal for instructing the reception antenna 1042 to transmit a reception sensitivity adjustment signal is transmitted to the portable device 200.

  On the other hand, when receiving the transmission instruction signal, the control device 210 of the portable device 200 is configured to keep the UHF transmission circuit 208 transmitting the reception sensitivity adjustment signal to the reception antenna 1042 of the UHF receiver 104.

  When the reception optimization signal is received by the reception antenna 1042 in the matching optimization unit 1050 (strictly speaking, when the voltage detection unit 1048 starts to detect the voltage of the electrical signal obtained by demodulating the reception sensitivity adjustment signal by the reception circuit 1044). Then, optimization of impedance matching between the reception antenna 1042 and the reception circuit 1044 is started.

  When the optimization of impedance matching is completed, the control unit 106 of the in-vehicle device 100 is caused to transmit a transmission stop instruction signal for instructing to stop transmission of the reception sensitivity adjustment signal to the portable device 200. When receiving the transmission stop instruction signal, the control device 210 of the portable device 200 causes the UHF transmission circuit 208 to stop transmitting the reception sensitivity adjustment signal.

  An example of the control flow of the matching optimization unit 1050 that adjusts the reception sensitivity of the UHF receiver 104 described so far will be described with reference to the flow shown in FIG.

  As shown in FIG. 5, the alignment optimization unit 1050 starts by detecting the movement of the equipment via the equipment movement sensor 56 in S510.

  Next, in S520, it is determined whether the portable device 200 exists in the vehicle. As described above, the presence of the portable device 200 in the vehicle interior transmits a request signal from the transmission antennas 102d and 102e for the vehicle interior of the in-vehicle device 100 to the portable device 200, and the in-vehicle device receives the request signal from the portable device 200. An ID signal is transmitted to the machine 100 for confirmation. After confirming that the portable device 200 exists in the vehicle interior, it is determined to adjust the reception sensitivity of the UHF receiver 104 (to optimize impedance matching between the reception antenna 1042 and the reception circuit 1044).

  This is because there is a possibility that the portable device 200 exists in the passenger compartment, and that the portable device 200 may be maintained at a substantially constant position with respect to the UHF receiver 104, when the portable device 200 exists outside the passenger compartment. If the portable device 200 that transmits the reception sensitivity adjustment signal is moving when the reception sensitivity of the UHF receiver 104 is adjusted, the reception antenna 1042 of the UHF receiver 104 stably stabilizes the signal. This is because it is difficult to adjust the reception sensitivity due to failure in reception.

  When it is determined in S520 that the portable device 200 is present in the passenger compartment and the reception sensitivity of the UHF receiver 104 is determined to be adjusted, in S530, the portable device 200 transmits a reception sensitivity adjustment signal. A transmission instruction signal is transmitted to the portable device 200.

  In S540, the reception sensitivity adjustment signal from the portable device 200 is received, and the matching optimization unit 1050 optimizes impedance matching between the reception antenna 1042 and the reception circuit 1044.

  When optimization of impedance matching between the receiving antenna 1042 and the receiving circuit 1044 is completed, a transmission stop instruction signal is transmitted to the portable device 200 in order to stop the portable device 200 from transmitting the reception sensitivity adjustment signal in S550. To do.

  The flow shown in FIG. 5 shows the flow of control performed when the state of the passenger compartment changes due to the movement of the equipment whose movement is detected by the equipment movement sensor 56. When the reception sensitivity of the UHF receiver 104, which has changed due to the change in the state of the passenger compartment due to the movement of equipment, passengers, luggage, etc., whose movement is not detected by the equipment movement sensor 56, is satisfactorily adjusted. The control from S530 to S550 may be executed periodically.

  According to the present embodiment, the reception sensitivity of the UHF receiver 104 that has changed due to a change in the state of the passenger compartment is detected based on the voltage of the electrical signal demodulated from the radio signal by the reception circuit 1044, and the voltage (reception sensitivity). Based on the above, the matching circuit 1046 is controlled to optimize the impedance matching between the receiving antenna 1042 and the receiving circuit 1044 after the state of the vehicle interior changes. As a result, the reception sensitivity deteriorated due to the change in the state of the passenger compartment is improved, and good wireless communication can be performed between the portable device 200 and the in-vehicle device 100.

  From another viewpoint, it can be said that the reception sensitivity can be well adjusted even in vehicles having different vehicle interior conditions, that is, different vehicle types. Therefore, a common smart keyless entry system can be installed in each vehicle of different vehicle types.

  Although the present invention has been described with reference to the above-described embodiment, the present invention is not limited to this.

  For example, in the above-described embodiment, the matching circuit includes a coil and a variable capacitance capacitor. However, other configurations may be used as long as impedance matching between the receiving antenna and the receiving circuit can be optimized.

  Further, the above-described embodiment assumes that the portable device is maintained at a substantially constant position with respect to the UHF receiver when the portable device is present in the passenger compartment (compared to the outside of the passenger compartment in the passenger compartment). It is intended to adjust the reception sensitivity of the UHF receiver when the portable device is present in the passenger compartment, assuming that the portable device will not move. However, the signal for adjusting the reception sensitivity from the portable device is more stable. A holder for holding the portable device in a fixed position with respect to the UHF receiver may be added to the components of the smart keyless entry system so that the receiving antenna of the UHF receiver can receive the signal.

  For example, the holder is installed on a dashboard in front of the driver's seat, and a portable device is placed on the holder by an occupant. Accordingly, the portable device is kept stationary with respect to the UHF receiver, and the reception sensitivity adjustment signal from the portable device can be stably received by the reception antenna of the UHF receiver.

  Note that there is a situation in which the portable device is considered to be substantially immovable with respect to the UHF receiver without providing a holder. The portable device is most likely to be carried and operated by the driver, and the driver cannot operate the portable device while driving the vehicle. Therefore, it can be considered that the distance between the receiving antenna and the portable device is maintained substantially constant. Therefore, by optimizing the impedance matching between the reception antenna and the reception circuit by the matching optimization unit while the vehicle is running, the reception sensitivity adjustment signal from the portable device can be stably supplied to the UHF receiver. The receiving antenna can receive signals, and impedance matching can be easily optimized. Note that whether or not the vehicle is running can be known from a vehicle speed sensor, for example.

  Furthermore, in the above-described embodiment, the adjustment of the reception sensitivity of the UHF receiver is automatically executed from the viewpoint of the passenger. Alternatively or additionally, the reception sensitivity of the UHF receiver may be adjusted according to the occupant's intention (by the occupant's operation).

  For example, when the above-mentioned holder and reception sensitivity adjustment switch are added to the components of the smart keyless entry system, the passenger places the portable device in the holder and presses the reception sensitivity adjustment switch, the reception sensitivity adjustment is performed from the in-vehicle device to the portable device. A signal instructing transmission of the signal for use is transmitted, and the portable device that has received this signal transmits a signal for adjusting reception sensitivity to the UHF receiver of the vehicle-mounted device. The matching optimization unit of the UHF receiver satisfactorily adjusts the reception sensitivity of the UHF receiver by this reception sensitivity adjustment signal, and when the adjustment is completed, for example, an alarm (for example, from the alarm device 54 shown in FIGS. 1 and 2). Sound) to inform the occupant of the completion of adjustment.

  As another form, when the occupant operates the portable device in a predetermined procedure, the portable device transmits a reception sensitivity adjustment signal to the UHF receiver, and the matching optimization unit of the UHF receiver receives the reception sensitivity adjustment signal. The reception sensitivity of the UHF receiver may be adjusted well.

  For example, in the case of having a plurality of buttons as in the portable device 100 shown in FIG. 1, the portable device is configured so that the reception sensitivity adjustment signal is continuously transmitted while the plurality of buttons are being pressed at the same time. When the adjustment of the reception sensitivity of the UHF receiver is completed by the conversion unit using the reception sensitivity adjustment signal, a plurality of adjustments are completed via an alarm (for example, a sound from the alarm device 54 shown in FIGS. 1 and 2). Let the passengers keep pressing the button.

  In addition, in the above-described embodiment, the reception sensitivity of the UHF receiver is adjusted by a reception sensitivity adjustment signal from the portable device, that is, a dedicated signal, but the present invention is not limited to this.

  For example, in the above-described embodiment, in order to confirm that the portable device 200 exists in the passenger compartment, the request signal is transmitted to the portable device 200 from the transmission antennas 102d and 102e for the passenger compartment, and the request signal is received. An ID signal is transmitted from the portable device 200 to the in-vehicle device 100. The reception sensitivity of the UHF receiver may be adjusted using this ID signal.

  As described above, according to the present invention, the in-vehicle device of the smart keyless entry system can satisfactorily receive a signal from the portable device. Therefore, it may be suitably used in the field of the vehicle manufacturing industry equipped with the smart keyless entry system.

It is a figure showing a vehicle carrying a smart keyless entry system according to an embodiment of the present invention and a portable device of the system. It is a figure which shows the structure of the smart keyless entry system which concerns on one Embodiment of this invention. It is a figure which shows the transmission range of several LF transmission antenna with which the vehicle equipment of a smart keyless entry system is provided. It is a figure which shows the structure of a UHF receiver. It is a figure which shows the control flow for adjusting the receiving sensitivity of a UHF receiver.

Explanation of symbols

50 On-board control equipment (door lock actuator)
52 On-board control equipment (ECU)
54 In-vehicle control equipment (alarm)
DESCRIPTION OF SYMBOLS 100 In-vehicle apparatus 200 Portable apparatus 1042 Reception antenna 1044 Reception circuit 1046 Matching circuit 1048 Voltage detection means (voltage detection part)
1050 Matching optimization means (matching optimization unit)

Claims (6)

A smart keyless entry system comprising a vehicle-mounted device mounted on a vehicle and a portable device carried by an occupant, wherein the vehicle-mounted device receives a radio signal from the portable device and controls a vehicle-mounted control device,
The in-vehicle device performs impedance matching between the receiving antenna that receives a radio signal from the portable device, a receiving circuit that demodulates the radio signal received by the receiving antenna into an electric signal, and the receiving antenna and the receiving circuit. A matching circuit; voltage detecting means for detecting a voltage of an electrical signal demodulated by the receiving circuit; and an impedance between the receiving antenna and the receiving circuit by controlling the matching circuit based on the voltage detected by the voltage detecting means. A smart keyless entry system comprising: a matching optimization unit that optimizes matching. In the smart keyless entry system according to claim 1,
The matching circuit includes a coil provided between the receiving antenna and the receiving circuit, and a variable capacitance capacitor having one end connected between the coil and the receiving circuit and the other end grounded.
The smart keyless entry system, wherein the matching optimization unit controls the capacitance of the capacitor. The smart keyless entry system according to claim 1 or 2,
Equipment movement detection means for detecting that the equipment of the vehicle has moved,
The matching optimization means controls the matching circuit to optimize impedance matching between the receiving antenna and the receiving circuit when the equipment movement detecting means detects movement of the equipment. Smart keyless entry system. In the smart keyless entry system according to any one of claims 1 to 3,
The smart keyless entry system, wherein the vehicle equipment is at least one of a steering, a seat, and a movable roof. In the smart keyless entry system according to any one of claims 1 to 4,
When the matching optimization unit optimizes impedance matching between the reception antenna and the reception circuit, the matching optimization unit includes a wireless signal transmission execution unit that causes the portable device to transmit a wireless signal to the reception antenna. Smart keyless entry system. In the smart keyless entry system according to any one of claims 1 to 5,
The smart keyless entry system characterized in that the matching optimization means optimizes impedance matching between the receiving antenna and the receiving circuit while the vehicle is running.

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