JP2019044518A - In-vehicle unit, communication system for vehicle, communication processing method and control program - Google Patents

Abstract

To provide an in-vehicle unit that allows for increase in a transmission range of a signal to be transmitted from a vehicle to a portable unit and allows for elimination of the problem of a dead zone range and that can perform radio communication with the portable unit within the increased transmission range.SOLUTION: The in-vehicle unit causes at least two transmission antenna and indoor antenna disposed on a vehicle so as to be separated from each other to transmit signals and, in response to a response signal from a portable unit having received the transmitted signals, performs processing. The in-vehicle unit comprises: a transmission control part causing the two transmission antennas to simultaneously transmit the signals; a strength change part that when no response signal in response to the signals caused to be transmitted from the two transmission antennas is received from the portable unit, changes transmission strength of the indoor antenna so that the portable unit outside the vehicle can receive the signals; and an indoor transmission control part causing the indoor antenna to transmit a signal using the transmission strength changed by the strength change part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle-mounted device, a vehicle communication system, a communication processing method, and a control program.

A vehicle communication system that locks and unlocks a vehicle door without using a mechanical key has been put into practical use. Specifically, a keyless entry system that locks or unlocks a vehicle door by wireless remote control using a portable device possessed by the user, a user who possesses the portable device only approaches the vehicle or holds the door handle The Smart Entry (registered trademark) system that unlocks vehicle doors has been put into practical use.
Further, a vehicle communication system that starts a vehicle engine without using a mechanical key has been put into practical use. Specifically, a push start system in which a user having a portable device starts an engine only by pressing an engine start button has been put into practical use.
Furthermore, an automatic locking system that automatically locks a vehicle door when a user carrying a portable device moves away from the vehicle has been put into practical use.

  In such a vehicle communication system, the in-vehicle device performs wireless communication with the portable device. In the wireless communication, a signal is transmitted from a transmission antenna of an in-vehicle device to a portable device using an LF (Low Frequency) band radio wave, and the portable device that receives the signal uses an UHF (Ultra High Frequency) band radio wave. This is done by sending a response signal. The in-vehicle device performs control such as unlocking, locking, engine starting, locking, etc. after performing authentication and confirming the position of the portable device.

  By the way, the signal transmitted from the vehicle-mounted device is the LF band, and the transmission range of the signal, that is, the range in which the portable device can receive the signal is limited to a predetermined range around the vehicle. When an antenna for transmitting an LF band signal is shared by a plurality of systems, the transmission range of signals required for each system is different, so the specifications of both systems cannot be satisfied. For example, a transmission antenna provided in a tire pressure monitoring system is arranged at each tire position of a vehicle. In order to use the transmission antenna as a transmission antenna of an automatic locking system, it is necessary to expand a transmission range.

  In order to expand the transmission range, the signal reception sensitivity of the portable device may be set to a high sensitivity, but the life of the battery that drives the portable device is shortened. As a technique for solving such a problem, Patent Document 1 discloses a technique for expanding a transmission range of a signal by simultaneously transmitting the signal from two transmission antennas.

International Publication No. 2016/082516

  However, when signals are transmitted simultaneously from two or more transmitting antennas that are separated from each other in a vehicle, there is a problem that a region where the amplitude is locally reduced occurs even though the signal is within the transmission range near the vehicle. There is. That is, by simultaneously transmitting signals from two or more transmission antennas, the transmission range can be expanded, but a region in which the portable device cannot receive the signals locally occurs. Hereinafter, this area is referred to as a dead zone area.

  An object of the present invention is to expand the transmission range of a signal transmitted from a vehicle to a portable device, solve the problem of the dead zone, and perform wireless communication with a portable device within the expanded transmission range. An in-vehicle device, a vehicle communication system, a communication processing method, and a control program are provided.

  The in-vehicle device according to the present aspect transmits a signal from at least two transmission antennas spaced apart in the front and rear of the vehicle and an indoor antenna that radiates radio waves into the vehicle interior, and a response signal from the portable device that has received the signal An in-vehicle device that performs processing according to the transmission control unit that simultaneously transmits the signals from the two transmission antennas, and the response from the portable device to the signals transmitted from the two transmission antennas. When the signal is not received, an intensity changing unit that changes the transmission intensity of the signal transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal; and And an indoor transmission control unit that transmits the signal from the indoor antenna with the transmission intensity changed in this way.

  The vehicle communication system according to this aspect is transmitted from the vehicle-mounted device, at least two transmission antennas that are spaced apart from the front and rear of the vehicle, an indoor antenna that radiates radio waves into the vehicle interior, and the vehicle-mounted device. A portable device that receives the signal and transmits a response signal in accordance with the received signal.

  In the communication processing method according to the present aspect, a signal is transmitted from at least two transmission antennas that are spaced apart from the front and rear of the vehicle and an indoor antenna that radiates radio waves to the interior of the vehicle, and a response from the portable device that has received the signal. A communication processing method for performing processing according to a signal, wherein the signals are simultaneously transmitted from the two transmission antennas, and the response signal from the portable device is transmitted to the signals transmitted from the two transmission antennas. If the signal is not received, the transmission intensity of the signal transmitted from the indoor antenna is changed so that the portable device outside the vehicle can receive the signal. The signal is transmitted.

  The control program according to the present aspect includes: the two transmission antennas and the indoor antenna connected to an on-vehicle device connected to at least two transmission antennas spaced apart in the front and rear of the vehicle and an indoor antenna that radiates radio waves into the vehicle interior. A control program for transmitting a signal from a mobile device and executing a process according to a response signal from a portable device that has received the signal, wherein the signal is simultaneously transmitted from the two transmission antennas, and the two transmission antennas Transmission of the signal transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal when the response signal from the portable device to the signal transmitted from the portable device is not received. The strength is changed, and the vehicle-mounted device is caused to execute a process of transmitting the signal from the indoor antenna with the changed transmission strength.

  According to the above, the transmission range of the signal transmitted from the vehicle to the portable device can be expanded, the problem of the dead zone can be solved, and wireless communication can be performed with the portable device in the expanded transmission range. An in-vehicle device, a vehicle communication system, a communication processing method, and a control program can be provided.

It is a schematic diagram explaining the structural example of the communication system for vehicles which concerns on this embodiment. It is a block diagram which shows the structural example of the vehicle equipment which concerns on this embodiment. It is a block diagram which shows the structural example of a vehicle-mounted transmission part. It is explanatory drawing which shows the transmission range at the time of transmitting a signal separately from each LF transmitting antenna. It is explanatory drawing which shows the transmission range at the time of transmitting a signal simultaneously from two LF transmission antennas spaced apart before and behind the vehicle. It is a distribution map which shows an example of the magnetic field distribution of the signal wave transmitted from two LF transmission antennas spaced apart before and behind the vehicle. It is explanatory drawing which shows the transmission range at the time of transmitting a signal from an indoor LF transmission antenna. It is a block diagram which shows the structural example of a detection apparatus. It is a block diagram which shows the structural example of a portable machine. It is a flowchart which shows the process sequence of the vehicle equipment and portable device which concern on this embodiment. It is a flowchart which shows the process sequence of the vehicle equipment and portable device which concern on this embodiment.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. Moreover, you may combine arbitrarily at least one part of embodiment described below.

(1) The vehicle-mounted device according to this aspect transmits signals from at least two transmission antennas that are spaced apart from the front and rear of the vehicle and an indoor antenna that radiates radio waves into the vehicle interior, and from the portable device that has received the signals. An in-vehicle device that performs processing in response to a response signal of the transmission, a transmission control unit that simultaneously transmits the signals from the two transmission antennas, and the portable device that transmits the signals transmitted from the two transmission antennas An intensity changing unit that changes the transmission intensity of the signal transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal when the response signal is not received; An indoor transmission control unit that transmits the signal from the indoor antenna with the transmission intensity changed by the changing unit.

In this aspect, the transmission range of a signal transmitted from one transmission antenna is within a limited range around the vehicle, and a portable device outside the transmission range cannot receive the signal. Therefore, the in-vehicle device transmits signals from two or more transmission antennas simultaneously. Signals transmitted simultaneously from two or more transmission antennas are superimposed and the amplitude is increased. Therefore, the transmission range of the signal transmitted from the transmission antenna of the in-vehicle device can be expanded.
On the other hand, when signals are transmitted simultaneously from two or more transmitting antennas that are spaced apart from each other in the vehicle, a dead zone region in which the amplitude is locally reduced occurs despite being within the transmission range near the vehicle. The dead zone region is considered to occur in the vicinity of the vehicle based on the result of simulation. When there is a portable device in the area, a signal transmitted from the transmission antenna cannot be received. As described above, by simultaneously transmitting signals from two or more transmission antennas, the transmission range can be expanded, but a region in which the portable device cannot receive the signals locally occurs. Hereinafter, this area is referred to as a dead zone area.
Therefore, when the in-vehicle device does not receive a response signal from the portable device for the signals transmitted simultaneously, the in-vehicle device increases the transmission strength of the indoor antenna by the strength changing unit and transmits the signal from the indoor antenna. Let Since the dead zone area is in the vicinity of the vehicle, even when a signal is transmitted from the indoor antenna, by increasing the transmission intensity of the indoor antenna, the signal reaches the dead zone area while maintaining a sufficient amplitude, The portable device can receive a signal transmitted from the indoor antenna.
Therefore, the vehicle-mounted device according to this aspect can expand the transmission range of the signal transmitted from the transmission antenna and also solve the problem of the dead zone region.

(2) The indoor transmission control unit causes the transmission control unit to transmit the signal having the first transmission strength from the indoor antenna to the portable device before the signal is transmitted from the two transmission antennas. When the transmission control unit does not receive the response signal from the portable device with respect to the signal having the first transmission intensity transmitted from the indoor antenna, the transmission control unit transmits the signal simultaneously from the two transmission antennas. And the indoor transmission control unit is stronger than the first transmission intensity when not receiving the response signal from the portable device with respect to the signal transmitted from the two transmission antennas, A configuration in which the signal is transmitted from the indoor antenna at a second transmission intensity at which the portable device can receive the signal is preferable.

  According to this aspect, after confirming that there is no portable device in the vehicle interior, signals are simultaneously transmitted from the two transmission antennas to the portable devices around the vehicle, and processing according to the response signal from the portable device is performed. It can be carried out. For example, it is possible to detect that there is no portable device in the vehicle interior or the vicinity of the vehicle, and execute a required process.

(3) A position detection unit that detects the position of the portable device according to whether the response signal is received from the portable device with respect to the signal transmitted by the transmission control unit and the indoor transmission control unit. The structure provided is preferable.

  In this aspect, when a response signal is received from a portable device with respect to signals transmitted from two transmission antennas or indoor antennas, the signal is transmitted within the transmission range of signals transmitted simultaneously from the two transmission antennas. It can be determined that there is a machine.

(4) After the door of the vehicle is opened and closed, when the response signal from the portable device to the signal transmitted by the transmission control unit and the indoor transmission control unit is not received, the locking of the door is controlled. The structure provided with the locking control part to perform is preferable.

  In this aspect, when there is no response from the portable device to any of the signals transmitted simultaneously from the two transmission antennas and the signal transmitted from the indoor antenna, the portable device has an expanded transmission range. It is determined that the vehicle door is not inside, and the vehicle door is locked.

(5) A configuration in which the signal in the LF (Low Frequency) band is transmitted from the two transmission antennas and the indoor antenna is preferable.

In this aspect, since the signals transmitted simultaneously from the respective transmission antennas are LF band signals, the amplitude of each signal around the vehicle is uniform. Therefore, in the region where the directions of the magnetic fields of the signal waves emitted from the respective transmitting antennas are aligned, the signals do not interfere and weaken, and the signal strength increases by simple superposition of the signals.
However, as described above, there is a region where the amplitude becomes small when signals are transmitted simultaneously from two or more transmitting antennas that are spaced apart from each other in the vehicle.

(6) A configuration including a phase control unit that controls the phase of the signal to be transmitted simultaneously from the two transmission antennas is preferable.

  In this aspect, it is possible to control the direction in which the signal transmission range is expanded by controlling the phase of the signals to be transmitted simultaneously.

(7) The two transmission antennas include a magnetic core whose axial direction is a front-rear direction in the traveling direction of the vehicle, and a coil whose winding direction with respect to each magnetic core is the same as each other, and the phase control unit Is preferably configured to control the phases of the signals transmitted from the two transmitting antennas spaced apart from each other in the traveling direction of the vehicle in opposite phases.

  In this aspect, the transmission range of the signal can be expanded in the left-right direction of the vehicle by controlling the phase of the signal transmitted from the transmission antennas spaced apart from each other in the front and rear of the vehicle. it can.

(8) The two transmission antennas include a magnetic core whose axial direction is a front-rear direction in the traveling direction of the vehicle, and coils whose winding directions with respect to the magnetic cores are opposite to each other, and the phase control The unit is preferably configured to control the phase of the signal transmitted from the two transmission antennas spaced apart from each other in the traveling direction of the vehicle in phase.

  In this aspect, the signal transmission range can be expanded in the left-right direction of the vehicle by controlling so that the phase of the signal transmitted from the transmission antennas spaced apart from the front and rear of the vehicle is in phase. .

(9) The transmission antenna is arranged at each tire position where the plurality of tires of the vehicle are provided, and is provided on each of the plurality of tires, and wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tires. It is preferable to include a request signal transmission control unit that transmits a pneumatic pressure information request signal for requesting pneumatic pressure information from the transmission antennas arranged at each tire position to a plurality of detection devices.

  In this aspect, the vehicle-mounted device can communicate with a detection device that detects tire air pressure using a plurality of transmission antennas.

(10) A vehicle communication system according to this aspect includes any one of the vehicle-mounted devices according to aspects (1) to (9), at least two transmission antennas spaced apart before and after the vehicle, An indoor antenna that radiates radio waves indoors and a portable device that receives the signal transmitted from the in-vehicle device and transmits a response signal according to the received signal.

(11) A communication processing method according to this aspect includes a portable device that transmits a signal from at least two transmission antennas that are spaced apart from each other at the front and rear of the vehicle and an indoor antenna that radiates a radio wave to the vehicle interior and receives the signal. A communication processing method for performing processing in response to a response signal from the two transmitting antennas, wherein the signals are transmitted simultaneously from the two transmitting antennas, and the portable device responds to the signals transmitted from the two transmitting antennas. When the response signal is not received, the transmission intensity of the signal transmitted from the indoor antenna is changed so that the portable device outside the vehicle can receive the signal, with the changed transmission intensity, The signal is transmitted from the indoor antenna.

(12) The control program according to this aspect includes at least two transmission antennas spaced apart in front and rear of a vehicle and an in-vehicle device connected to an indoor antenna that emits radio waves into the vehicle interior. A control program for transmitting a signal from the indoor antenna and executing a process according to a response signal from a portable device that has received the signal, wherein the signal is simultaneously transmitted from the two transmission antennas, If the response signal from the portable device to the signals transmitted from two transmission antennas is not received, the portable device outside the vehicle is transmitted from the indoor antenna so that the signal can be received. The transmission intensity of the signal is changed, and the vehicle-mounted device is caused to execute a process of transmitting the signal from the indoor antenna with the changed transmission intensity.

  In this aspect (10), (11), and (12), as in aspect (1), the transmission range of the signal transmitted from the transmission antenna can be expanded, and the problem of the dead zone region can be solved. .

[Details of the embodiment of the present invention]
Specific examples of the in-vehicle device, the vehicle communication system, the communication processing method, and the control program according to the embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

Hereinafter, the present invention will be specifically described with reference to the drawings illustrating embodiments thereof.
<Vehicle communication system>
FIG. 1 is a schematic diagram illustrating a configuration example of a vehicle communication system according to the present embodiment. The vehicle communication system according to the present embodiment includes an in-vehicle device 1 provided at an appropriate location of the vehicle body, a plurality of detection devices 2 provided on each of the wheels of a plurality of tires 3 attached to the vehicle C, and a notification device. 4, a portable device 5, and a locking / unlocking unit 6, and a tire pressure monitoring system and an automatic locking system are configured.

  The in-vehicle device 1 is connected to a first LF transmission antenna 10a, a second LF transmission antenna 10b, a third LF transmission antenna 10c, a fourth LF transmission antenna 10d, and a plurality of indoor LF transmission antennas 1a. The first to fourth LF transmission antennas 10a, 10b, 10c, and 10d are spaced apart from each other at the right front, right rear, left front, and left rear tire positions of the vehicle C to which the four tires 3 are attached, for example. The tire position is the position of the tire house and its surroundings, and the detection device 2 provided in each tire 3 receives the signals transmitted from the first to fourth LF transmitting antennas 10a, 10b, 10c, and 10d, respectively. It is a position that can be done. The indoor LF transmitting antenna 1a is arranged on the front side and the rear side of the substantially central portion in the left-right direction of the vehicle C so that radio waves are mainly emitted into the vehicle interior. The number and position of the indoor LF transmission antennas 1a are not particularly limited.

  In the following description, when it is not necessary to distinguish between the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d, the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d are simply referred to as LF transmission antennas. Also described as 10.

  In the vehicle communication system functioning as a tire pressure monitoring system, the vehicle-mounted device 1 sends a pneumatic pressure information request signal for requesting pneumatic pressure information of the tire 3 from the first to fourth LF transmitting antennas 10a, 10b, 10c, 10d to the LF band. Each detector 2 is transmitted separately by radio waves. The detection device 2 detects the air pressure of the tire 3 in response to the air pressure information request signal, and wirelessly transmits the air pressure signal including the air pressure information obtained by the detection and its own sensor identifier to the in-vehicle device 1 using the UHF band radio wave. To do. The in-vehicle device 1 includes an RF receiving antenna 13a, receives the air pressure signal transmitted from each detection device 2 by the RF receiving antenna 13a, and acquires the air pressure information of each tire 3 from the air pressure signal. The in-vehicle device 1 is connected to the notification device 4 via a communication line, and the in-vehicle device 1 transmits the acquired air pressure information to the notification device 4. The notification device 4 receives the air pressure information transmitted from the in-vehicle device 1 and notifies the air pressure information of each tire 3. Further, the notification device 4 issues a warning when the air pressure of the tire 3 is less than a predetermined threshold value.

On the other hand, in the vehicle communication system functioning as an automatic locking system, the vehicle-mounted device 1 uses signals for detecting the portable device 5 around the vehicle C (hereinafter referred to as a position detection signal) as the first to fourth LFs. The transmitting antennas 10a, 10b, 10c, and 10d are transmitted to the portable device 5 by radio waves in the LF band. The in-vehicle device 1 detects the portable device 5 in the vehicle interior by transmitting a position detection signal from the indoor LF transmission antenna 1a to the portable device 5 using radio waves in the LF band.
When the portable device 5 receives the position detection signal transmitted from the first to fourth LF transmission antennas 10a, 10b, 10c, 10d or the indoor LF transmission antenna 1a, the portable device 5 sends a response signal corresponding to the received position detection signal to UHF. It transmits to the vehicle equipment 1 by the radio wave of the band. The in-vehicle device 1 receives the response signal transmitted from the portable device 5 by the RF receiving antenna 13a. When it is determined that the portable device 5 does not exist in the vehicle interior and is far away from the vehicle C by wireless communication with the portable device 5, the in-vehicle device 1 drives the locking / unlocking unit 6 to drive the door of the vehicle C (hereinafter referred to as “door”). The vehicle door is locked. As described above, when the user carrying the portable device 5 leaves the vehicle C, the vehicle door is automatically locked.

  Note that the LF band and the UHF band used in the vehicle communication system according to the present embodiment are examples of radio wave bands used when performing wireless communication, and are not necessarily limited thereto.

<In-vehicle device>
FIG. 2 is a block diagram illustrating a configuration example of the in-vehicle device 1 according to the present embodiment. The in-vehicle device 1 includes a control unit 11 that controls the operation of each component of the in-vehicle device 1. The control unit 11 is connected to a storage unit 12, an in-vehicle reception unit 13, an in-vehicle transmission unit 14, an in-vehicle communication unit 15, and an input unit 16.

  The control unit 11 includes, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface. The CPU of the control unit 11 is connected to the storage unit 12, the in-vehicle receiving unit 13, the in-vehicle transmitting unit 14, and the in-vehicle communication unit 15 through an input / output interface. The control unit 11 executes the control program 12a stored in the storage unit 12 to control the operation of each component unit, to detect the position of the portable device 5, an automatic locking function, and a tire pressure monitoring function. This process is executed.

  The control unit 11 is not limited to the above configuration, and may be one or more processing circuits including a single core CPU, a multicore CPU, a volatile or nonvolatile memory, a microcomputer, and the like. Further, the control unit 11 may have functions such as a clock for measuring time, a timer for measuring an elapsed time from giving a measurement start instruction to giving a measurement end instruction, and a counter for counting the number.

  The storage unit 12 is a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The storage unit 12 is a control program for realizing the function of detecting the position of the portable device 5, the automatic locking function, and the tire pressure monitoring function by the control unit 11 controlling the operation of each component of the in-vehicle device 1. 12a is stored.

  An RF receiving antenna 13 a is connected to the in-vehicle receiving unit 13. The in-vehicle receiving unit 13 receives a signal transmitted from the portable device 5 or the detection device 2 using radio waves in the RF band by the RF receiving antenna 13a. The in-vehicle receiving unit 13 is a circuit that demodulates the received signal and outputs the demodulated signal to the control unit 11. Although a UHF band of 300 MHz to 3 GHz is used as a carrier wave, the carrier wave is not limited to this frequency band.

The in-vehicle transmission unit 14 is connected to the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d and the indoor LF transmission antenna 1a. The first to fourth LF transmission antennas 10 a, 10 b, 10 c, and 10 d include a rod-shaped magnetic core made of ferrite and a coil wound around the outer periphery of the magnetic core of each LF transmission antenna 10. The first to fourth LF transmission antennas 10a, 10b, 10c, and 10d are arranged at tire positions on the front and rear, left and right of the vehicle C so that the axial direction of the magnetic core of the LF transmission antenna 10 is the front and rear direction of the vehicle C. ing. The winding directions of the coils wound around each magnetic core are the same. A capacitor is connected to the coil to form a resonance circuit. The resonance circuit is connected to the in-vehicle transmission unit 14. The configuration of the indoor LF transmission antenna 1 a is the same as that of the LF transmission antenna 10.
The in-vehicle transmission unit 14 modulates the signal output from the control unit 11 into an LF band signal, and carries the modulated signal from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d and the indoor LF transmission antenna 1a. This is a circuit for transmitting to the machine 5 or the detection device 2. The in-vehicle transmission unit 14 can simultaneously transmit signals from the plurality of LF transmission antennas 10. The in-vehicle transmission unit 14 causes a current to flow through the coil so that the transmission range of signals transmitted from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d is within a certain range around the vehicle. Send it. The transmission range is a range in which the portable device 5 can receive the signal. In addition, although the LF band of 30 kHz to 300 kHz is used as the carrier wave, it is not limited to this frequency band.

When performing position detection of the portable device 5, the in-vehicle transmission unit 14 transmits a position detection signal from the LF transmission antenna 10 or the indoor LF transmission antenna 1 a to the portable device 5. When there is a response from the portable device 5, the in-vehicle device 1 determines that the portable device 5 exists within the transmission range.
On the other hand, when transmitting a wake-up signal for activating the detection device 2 of each tire 3 to detect the tire pressure, or when causing each detection device 2 to transmit an air pressure information request signal, A wakeup signal or a pneumatic pressure information request signal is transmitted from the LF transmission antenna 10 separately.
In addition, you may comprise so that signal strengths, such as a wake-up signal transmitted to the detection apparatus 2, an air pressure information request signal, may become weak compared with the signal strength of the position detection signal transmitted to the portable device 5.

The in-vehicle communication unit 15 is a communication circuit that performs communication according to a communication protocol such as CAN (Controller Area Network) or LIN (Local Interconnect Network), and is connected to the notification device 4 and the locking / unlocking unit 6. When the air pressure of each tire 3 is detected, the in-vehicle communication unit 15 transmits the air pressure information of the tire 3 to the notification device 4 according to the control of the control unit 11.
On the other hand, when the authorized portable device 5 around the vehicle C is detected and the request switch is operated, the control unit 11 transmits a lock signal or an unlock signal to the lock / unlock unit 6. In addition, when the vehicle door is opened and closed while the ignition switch is off and the response from the portable device 5 to the position detection signal transmitted to the transmission range is lost, the on-vehicle device 1 unlocks the locking signal. Transmit to the lock 6.

  The notification device 4 is, for example, a display unit or an audio device provided with a speaker for notifying the air pressure information of the tire 3 transmitted from the in-vehicle communication unit 15 by an image or sound, a display unit provided in an instrument panel instrument, and the like. It is. The display unit is a liquid crystal display, an organic EL display, a head-up display, or the like. The notification device 4 displays the air pressure information of each tire 3 provided in the vehicle C.

The locking / unlocking unit 6 includes an actuator that drives a locking / unlocking mechanism that locks and unlocks the vehicle door. When receiving the locking signal or the unlocking signal, the locking / unlocking unit 6 drives the actuator to lock or unlock the vehicle door.
Further, the locking / unlocking unit 6 can control the operation of the locking / unlocking unit 6 in accordance with the operation of the locking / unlocking switch in the vehicle, and can lock or unlock the vehicle door, and information indicating the locking / unlocking state of the vehicle door Can be transmitted to the in-vehicle device 1 via the communication line.

  The input unit 16 is connected to a door open / close detection switch 7 and receives an open / close signal having a signal level corresponding to the open / close state of the vehicle door. The door open / close detection switch 7 is, for example, a courtesy switch. The control unit 11 can recognize the open / closed state of the vehicle door based on the open / close signal input to the input unit 16.

  FIG. 3 is a block diagram illustrating a configuration example of the in-vehicle transmission unit 14. The in-vehicle transmission unit 14 includes first to fourth transmission units 140a, 140b, 140c, which generate LF band signals transmitted from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d and the indoor LF transmission antenna 1a, respectively. 140d and the indoor transmission part 140e are provided.

  The first transmission unit 140a includes a signal generation circuit 141a and a phase shift circuit 142a. The signal generation circuit 141a superimposes a signal input from the control unit 11, for example, a signal wave of a position detection signal on a carrier wave, and modulates the signal into an LF band signal. The carrier wave is generated by an RC oscillation circuit, a crystal oscillation circuit or the like not shown in the figure. The signal wave modulated by the signal generation circuit 141a is input to the phase shift circuit 142a. The phase shift circuit 142 a controls the phase of the input signal wave based on, for example, a phase shift control signal input from the control unit 11. The first transmitter 140a transmits the signal wave whose phase is controlled by the phase shift circuit 142a to the outside through the first LF transmission antenna 10a.

  The configurations of the second to fourth transmission units 140b, 140c, and 140d are the same as the configuration of the first transmission unit 140a. That is, the second transmission unit 140b includes a signal generation circuit 141b and a phase shift circuit 142b, the third transmission unit 140c includes a signal generation circuit 141c and a phase shift circuit 142c, and the fourth transmission unit 140d includes a signal generation circuit 141d and a phase shift circuit 142c. A phase circuit 142d is provided. The second to fourth transmitters 140b, 140c, and 140d modulate a signal input from the controller 11, for example, a signal wave of a position detection signal onto a carrier wave and modulate the signal into an LF band signal, and then input from the controller 11 The phase is controlled based on the phase shift control signal to be transmitted, and the signal wave whose phase is controlled is transmitted from the second to fourth LF transmission antennas 10b, 10c, and 10d to the outside.

  The basic configuration of the indoor transmission unit 140e is similar to the configuration of the first transmission unit 140a, and includes a signal generation circuit 141e. Moreover, the indoor transmission part 140e contains the intensity | strength change part 143e. The intensity changing unit 143e is a circuit that changes the intensity of the signal generated by the signal generating circuit 141e and output to the indoor LF transmitting antenna 1a. The strength changing unit 143d is an amplifier circuit, for example, and is set to a specific transmission strength according to the strength control signal input from the control unit 11. The indoor transmission unit 140e transmits the signal amplified by the intensity changing unit 143e to the outside through the indoor LF transmission antenna 1a. As the transmission intensity that can be set in the intensity changing unit 143d, at least the first transmission intensity at which the portable device 5 at any position in the vehicle interior can receive a signal, and the signal reaches outside the vehicle interior, In particular, it includes the second transmission strength that enables the portable device 5 in the vicinity of the outside of the side surface of the vehicle C to receive a signal.

<Position detection method>
FIG. 4 is an explanatory diagram showing a transmission range when signals are separately transmitted from the LF transmission antenna 10. FIG. 4A conceptually shows transmission ranges 8a, 8b, 8c, and 8d when signals are transmitted separately from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d. The transmission ranges 8a, 8b, 8c, and 8d are areas in which the portable device 5 can receive signals transmitted from the LF transmission antennas 10. FIG. 4B is a timing chart showing transmission timings of signals transmitted from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d. The horizontal axis represents time, and the “signal” surrounded by a square represents the signal transmission timing.

A transmission range 8a of a signal transmitted from the single first LF transmission antenna 10a remains within a predetermined range centered on the first LF transmission antenna 10a. Similarly, the transmission range 8b of a signal transmitted from the single second LF transmission antenna 10b remains within a predetermined range centered on the second LF transmission antenna 10b. Therefore, the signal strength at the center in the front-rear direction of the vehicle C is weak, and the portable device 5 at the position shown in FIG. 4A can receive signals transmitted from the first and second LF transmitting antennas 10a and 10b. Can not.
Similarly, transmission ranges 8c and 8d of signals transmitted from the third and fourth LF transmission antennas 10c and 10d remain within a predetermined range centered on the third and fourth LF transmission antennas 10c and 10d, respectively.

  FIG. 5 is an explanatory diagram showing a transmission range when signals are transmitted simultaneously from two LF transmitting antennas 10 that are spaced apart from each other in front of and behind the vehicle C. FIG. FIG. 5A conceptually shows a transmission range 8ab when signals are transmitted simultaneously from the first and second LF transmission antennas 10a and 10b. FIG. 5B is a timing chart showing transmission timings of signals transmitted from the first to fourth LF transmission antennas 10a, 10b, 10c, and 10d. The horizontal axis represents time, and the “signal” surrounded by a square represents the signal transmission timing. In addition, each signal connected by a broken-line arrow indicates that the signals are opposite in phase.

As shown in FIG. 5A, the transmission range 8ab of the reverse-phase signal transmitted simultaneously from the first and second LF transmission antennas 10a and 10b is transmitted from the single first and second LF transmission antennas 10a and 10b. It expands compared to the signal transmission ranges 8a and 8b. Since the signals transmitted from the first and second LF transmission antennas 10a and 10b are in the LF band, the amplitude of the signal is uniform around the vehicle C, and basically the first and second LF transmission antennas 10a. The signals transmitted from 10b are superposed without being canceled by interference, and the amplitude increases. Therefore, for example, the portable device 5 at a position as shown in FIG. 5A can receive signals transmitted simultaneously from the first and second LF transmission antennas 10a and 10b.
However, when signals having opposite phases are transmitted simultaneously from the first and second LF transmitting antennas 10a and 10b, the amplitude of the signal is locally reduced on the right side surface of the vehicle C at the substantially central portion in the front-rear direction. A dead zone region occurs. The portable device 5 in the dead zone region cannot receive signals transmitted simultaneously from the first and second LF transmission antennas 10a and 10b. A hatched circular portion indicates a dead zone region. Hereinafter, the reason why the transmission range is expanded in the left-right direction and the dead zone region is generated by transmitting a signal having a reverse phase will be described.

  FIG. 6 is a distribution diagram showing an example of the magnetic field distribution of signal waves transmitted from the two LF transmitting antennas 10 that are spaced apart from the front and rear of the vehicle C. In the example of FIG. 6, the direction of the magnetic field generated when signals of opposite phases are transmitted simultaneously from the first and second LF transmission antennas 10a and 10b is shown. In the distribution diagram shown in FIG. 6, the X axis is taken in the direction that coincides with the left-right direction of the vehicle C, and the Y axis is taken in the direction that coincides with the front-rear direction of the vehicle C. The first and second LF transmission antennas 10a and 10b are both arranged on the Y axis, and are provided at a position equidistant from the X axis (for example, a position 1.2 m from the X axis). In addition, it is assumed that the axial directions of the magnetic cores included in the first and second LF transmitting antennas 10a and 10b are parallel to the Y axis, and the winding directions of the coils wound around the magnetic cores are the same.

  When signal waves having opposite phases are transmitted from the first and second LF transmitting antennas 10a and 10b, the directions of the magnetic fields of the signal waves emitted from the first and second LF transmitting antennas 10a and 10b are reversed in the vicinity of the origins of the X axis and the Y axis. As a result, it can be seen that the signal strength in the central region between the first and second LF transmission antennas 10a and 10b is smaller than that when one LF transmission antenna 10 is driven alone. The region where the signal intensity is reduced in this way is a dead zone region indicated by a hatched circular portion in FIG.

  On the other hand, in the region away from the Y axis, the magnetic fields of the signal waves transmitted from the first and second LF transmitting antennas 10a and 10b have components in the X axis direction. When signal waves having opposite phases are transmitted from the first and second LF transmitting antennas 10a and 10b, the directions of the magnetic fields of the signals emitted from the first and second LF transmitting antennas 10a and 10b are substantially the same in the vicinity of the X axis. As a result, the signal intensity in the vicinity of the X-axis away from the Y-axis, for example, in the vicinity of the position of the portable device 5 shown in FIG. 5A, becomes larger than when one LF transmitting antenna 10 is driven alone. I understand.

  In addition, since the magnetic field intensity at a position separated from the first LF transmission antenna 10a or the second LF transmission antenna 10b is small, the influence of one magnetic field on the other magnetic field is small. For this reason, the magnetic field strength in front of the first LF transmission antenna 10a and the magnetic field strength in the rear of the second LF transmission antenna 10b show values similar to the magnetic field strength when each is driven alone.

As described above, the signal transmission range 8a when the first LF transmission antenna 10a is used alone remains within a predetermined range centered on the first LF transmission antenna 10a. Similarly, the transmission range 8b when the second LF transmission antenna 10b is used alone remains within a predetermined range centered on the second LF transmission antenna 10b.
On the other hand, when the opposite-phase signal waves are transmitted simultaneously from the first LF transmission antenna 10a and the second LF transmission antenna 10b, the signal waves emitted from each are superimposed in the vicinity of the X axis apart from the Y axis, The transmission range 8ab determined by the combined magnetic field extends in the left-right direction near the center of the vehicle C in the front-rear direction.

The case where reverse-phase signals are transmitted simultaneously from the third and fourth LF transmission antennas 10c and 10d is the same as the case where reverse-phase signals are transmitted simultaneously from the first and second LF transmission antennas 10a and 10b. is there. The transmission ranges of the reverse-phase signals transmitted simultaneously from the third and fourth LF transmission antennas 10c and 10d are the transmission ranges 8c and 8d of the signals transmitted from the single third and fourth LF transmission antennas 10c and 10d. Compared to enlarge. Since the signals transmitted from the third and fourth LF transmission antennas 10c and 10d are in the LF band, the amplitude of the signal is uniform around the vehicle C, and basically the third and fourth LF transmission antennas 10c. The signals transmitted from 10d are superimposed without being canceled by interference, and the amplitude increases.
Therefore, even when opposite-phase signal waves are transmitted simultaneously from the third and fourth LF transmission antennas 10c and 10d, the signal wave transmission range is expanded in the left-right direction near the center of the vehicle C in the front-rear direction. Can do. In addition, when signals having opposite phases are transmitted simultaneously from the third and fourth LF transmitting antennas 10c and 10d, the amplitude of the signal is locally reduced on the left side surface of the vehicle C at the substantially central portion in the front-rear direction. A dead zone region occurs.

  As described above, the transmission range of the signal wave can be expanded in the left-right direction near the center of the vehicle C in the front-rear direction. By using this configuration, for example, by expanding the transmission range of the position detection signal for detecting the portable device 5, it is possible to detect the farther portable device 5 than moving away from the vehicle C in the left-right direction. However, the problem of the dead zone occurs.

  In addition, since the winding directions of the coils constituting the first to fourth LF transmitting antennas 10a, 10b, 10c, and 10d are the same, the transmission range is expanded by transmitting signal waves of opposite phases. When the winding directions of the coils constituting the first and second LF transmission antennas 10a and 10b are opposite to each other, by transmitting in-phase signal waves from the first and second LF transmission antennas 10a and 10b, It is good also as a structure which expands a transmission range. Similarly, when the winding directions of the coils constituting the third and fourth LF transmission antennas 10c and 10d are opposite to each other, in-phase signal waves are transmitted from the third and fourth LF transmission antennas 10c and 10d. Thus, the transmission range may be expanded.

FIG. 7 is an explanatory diagram showing a transmission range 8e when a signal is transmitted from the room. FIG. 7A shows a transmission range 8e of a signal transmitted from the indoor LF transmission antenna 1a at the first transmission intensity, and FIG. 7B shows a transmission range of a signal transmitted from the indoor LF transmission antenna 1a at the second transmission intensity. 8e is shown. In FIG. 7, the indoor LF transmission antenna 1a is not shown, and the transmission range 8e is illustrated.
As shown in FIG. 7A, the in-vehicle device 1 sets the first transmission intensity in the indoor transmission unit 140e, transmits the position detection signal from the indoor LF transmission antenna 1a, and detects the response from the portable device 5, It can be determined whether or not the portable device 5 is in the passenger compartment.

Moreover, as shown in FIG. 7B, the in-vehicle device 1 sets the second transmission intensity in the indoor transmission unit 140e, transmits a position detection signal from the indoor LF transmission antenna 1a, and detects a response from the portable device 5. Thus, it is possible to communicate with the portable device 5 in the vicinity of the outer side of both sides of the vehicle C, that is, the portable device 5 in the dead zone described with reference to FIG.
When the position detection signal is transmitted simultaneously from the first LF transmission antenna 10a and the second LF transmission antenna 10b, the transmission range 8ab of the position detection signal widens in the left-right direction as described above, but a dead zone region occurs. However, as shown in FIG. 7B, by transmitting the position detection signal from the indoor LF transmission antenna 1a with the second transmission intensity, the portable device 5 in the dead zone can be detected.

The in-vehicle device 1 of the present embodiment detects the position of the portable device 5 using the above characteristics. Specifically, the vehicle-mounted device 1 transmits position detection signals simultaneously from two LF transmission antennas 10 that are spaced apart in the front-rear direction. For example, the position detection signal is transmitted simultaneously from the first LF transmission antenna 10a and the second LF transmission antenna 10b. When the response signal from the portable device 5 with respect to the position detection signal is received, the control unit 11 of the in-vehicle device 1 can determine that the portable device 5 exists in the enlarged transmission range 8ab on the right side of the vehicle. Similarly, it is determined whether or not the portable device 5 exists within the expanded transmission range on the left side of the vehicle by simultaneously transmitting position detection signals from the third LF transmission antenna 10c and the fourth LF transmission antenna 10d. be able to.
When there is no response from the portable device 5 to the position detection signal, it is determined that the portable device 5 exists outside the transmission range or in the dead zone.

  In the present embodiment, when there is no response from the portable device 5, the control unit 11 increases the transmission intensity of the indoor LF transmission antenna 1a to determine whether the portable device 5 is in the dead zone region, Send a detection signal. When the response signal from the portable device 5 with respect to the position detection signal is received, it is determined that the portable device 5 is within the transmission range. If there is no response from the portable device 5 despite the transmission of the position detection signal from the indoor LF transmission antenna 1a, it is determined that the portable device 5 exists outside the transmission range.

<Detection device>
FIG. 8 is a block diagram illustrating a configuration example of the detection device 2. The detection device 2 includes a sensor control unit 21 that controls the operation of each component of the detection device 2. A sensor storage unit 22, a sensor transmission unit 23, a sensor reception unit 24, and an air pressure detection unit 25 are connected to the sensor control unit 21.

  The sensor control unit 21 includes, for example, a CPU, a ROM, a RAM, an input / output interface, and the like. The CPU of the sensor control unit 21 is connected to the sensor storage unit 22, the sensor transmission unit 23, the sensor reception unit 24, and the air pressure detection unit 25 via an input / output interface. The sensor control unit 21 reads a sensor control program stored in the sensor storage unit 22 and controls each unit. The detection device 2 includes a battery (not shown) and operates with electric power from the battery.

  The sensor control unit 21 is not limited to the above configuration, and may be one or more processing circuits including a single core CPU, a multicore CPU, a volatile or nonvolatile memory, a microcomputer, and the like. The sensor control unit 21 may include functions such as a clock for measuring time, a timer for measuring an elapsed time from giving a measurement start instruction to giving a measurement end instruction, and a counter for counting the number.

  The sensor storage unit 22 is a nonvolatile memory. The sensor storage unit 22 stores a sensor control program for the sensor control unit 21 to perform processing related to the detection of the air pressure of the tire 3 and the transmission of the air pressure signal. Further, a unique sensor identifier for identifying itself and the other detection device 2 is stored.

The air pressure detection unit 25 includes, for example, a diaphragm, and detects the air pressure of the tire 3 based on the deformation amount of the diaphragm that changes depending on the magnitude of the pressure. The air pressure detection unit 25 outputs a signal indicating the detected air pressure of the tire 3 to the sensor control unit 21. The sensor control unit 21 acquires the air pressure of the tire 3 from the air pressure detection unit 25 by executing a sensor control program, and generates a pneumatic signal including air pressure information and a sensor identifier unique to the detection device 2. The data is output to the transmission unit 23.
In addition, you may provide the temperature detection part (not shown) which detects the temperature of the tire 3 and outputs the signal which shows the detected temperature to the sensor control part 21. FIG. In this case, the sensor control unit 21 generates an air pressure signal including air pressure information, temperature information, a sensor identifier, and the like, and outputs the air pressure signal to the sensor transmission unit 23.

  An RF transmission antenna 23 a is connected to the sensor transmission unit 23. The sensor transmission unit 23 modulates the air pressure signal generated by the sensor control unit 21 into a UHF band signal, and transmits the modulated air pressure signal using the RF transmission antenna 23a.

  An LF receiving antenna 24 a is connected to the sensor receiving unit 24. The sensor receiver 24 receives the wake-up signal or air pressure information request signal transmitted from the vehicle-mounted device 1 using the LF band radio wave by the LF receiving antenna 24a, and receives the received wake-up signal or air pressure information request signal. Output to the sensor control unit 21.

<Portable machine>
FIG. 9 is a block diagram illustrating a configuration example of the portable device 5. The portable device 5 includes a portable control unit 51 that controls the operation of each component of the portable device 5. The portable control unit 51 is a microcomputer having, for example, one or a plurality of CPUs, a multi-core CPU, and the like. The portable control unit 51 is provided with a portable device storage unit 52, a portable transmission unit 53, and a portable reception unit 54. The portable device 5 includes a battery (not shown) and operates with electric power from the battery.

  The portable control unit 51 reads a later-described portable device control program stored in the portable device storage unit 52 and controls the operation of each component. The portable control unit 51 has a sleep state with low power consumption and an activated state with high power consumption.

  The portable device storage unit 52 is a nonvolatile memory similar to the storage unit 12. The portable device storage unit 52 executes processing for confirming that the regular portable device 5 exists around the vehicle C by controlling the operation of each component of the portable device 5 by the portable control unit 51. It stores a control program for a portable device.

  The portable transmission unit 53 is connected to the RF transmission antenna 53 a and transmits a response signal corresponding to the position detection signal transmitted from the in-vehicle device 1 according to the control of the portable control unit 51. The portable transmitter 53 transmits a response signal using UHF radio waves. The UHF band is an example of a radio wave band for transmitting signals, and is not necessarily limited to this.

  The portable receiving unit 54 is connected to the LF receiving antenna 54 a, receives various signals transmitted from the vehicle-mounted device 1 using radio waves in the LF band, and outputs the signals to the portable control unit 51. The LF reception antenna 54a is, for example, a triaxial antenna.

<Automatic locking procedure>
FIG. 10 is a flowchart showing a processing procedure of the in-vehicle device 1 and the portable device 5 according to the present embodiment. For example, the control unit 11 of the in-vehicle device 1 executes the following communication processing method at an appropriate timing after the vehicle door is opened and closed. More preferably, the control unit 11 executes the following processing at an appropriate timing after the engine is stopped, the shift position is in the parking position, and the vehicle door is opened and closed. The control unit 11 sets the transmission intensity of the indoor LF transmission antenna 1a to the first transmission intensity by outputting an intensity control signal to the indoor transmission unit 140e (step S111). And the control part 11 transmits a position detection signal from the indoor LF transmission antenna 1a by controlling the indoor transmission part 140e (step S112).

  The portable device 5 monitors the signal transmitted from the outside even in the resting state. When the portable device 5 is in the vehicle interior, when the position detection signal is transmitted from the in-vehicle device 1, the portable receiving unit 54 A position detection signal is received (step S113). The portable control unit 51 of the portable device 5 that has received the position detection signal shifts from the sleep state to the activated state (step S114), and transmits a response signal including its own identifier to the in-vehicle device 1 by the portable transmission unit 53 ( Step S115).

  The control unit 11 of the in-vehicle device 1 that has transmitted the position detection signal by the process of step S112 determines whether or not the in-vehicle reception unit 13 has received the response signal transmitted from the portable device 5 within a predetermined standby time. Determination is made (step S116). When it determines with having received the response signal (step S116: YES), the control part 11 finishes a process.

  When it is determined that the response signal has not been received (step S116: NO), the control unit 11 controls the in-vehicle transmission unit 14 to reverse the right front and right rear first LF transmission antennas 10a and second LF transmission antennas 10b. Phase position detection signals are transmitted simultaneously (step S117).

  When the portable device 5 is within the transmission range of the position detection signal, the portable device 5 receives the position detection signal at the portable reception unit 54 (step S118), and shifts from the sleep state to the activated state (step S119). A response signal including its own identifier is transmitted to the vehicle-mounted device 1 by the portable transmission unit 53 (step S120).

  The control unit 11 of the in-vehicle device 1 that has transmitted the position detection signal by the process of step S117 determines whether or not the in-vehicle reception unit 13 has received the response signal transmitted from the portable device 5 within a predetermined standby time. Determination is made (step S121). When it determines with having received the response signal (step S121: YES), the control part 11 returns a process to step S117.

  If it is determined that the response signal has not been received (step S121: NO), the control unit 11 controls the in-vehicle transmission unit 14 to reverse the left front and rear left third LF transmission antennas 10c and 4LF transmission antennas 10d. Phase position detection signals are transmitted simultaneously (step S122).

  When the portable device 5 is within the transmission range of the position detection signal, the portable device 5 receives the position detection signal at the portable reception unit 54 (step S123), and shifts from the sleep state to the activated state (step S124). A response signal including its own identifier is transmitted to the vehicle-mounted device 1 by the portable transmission unit 53 (step S125).

  The control unit 11 of the in-vehicle device 1 that has transmitted the position detection signal by the processing in step S122 determines whether or not the in-vehicle reception unit 13 has received the response signal transmitted from the portable device 5 within a predetermined standby time. Determination is made (step S126). When it determines with having received the response signal (step S126: YES), the control part 11 returns a process to step S117.

  When it is determined that the response signal has not been received (step S126: NO), the control unit 11 outputs the intensity control signal to the indoor transmission unit 140e, thereby changing the transmission intensity of the indoor LF transmission antenna 1a to the second transmission intensity. Setting is made (step S127). And the control part 11 transmits a position detection signal from the indoor LF transmission antenna 1a by controlling the indoor transmission part 140e (step S128).

  When the portable device 5 is in the dead zone of the position detection signal, the portable device 5 receives the position detection signal at the portable receiver 54 (step S129), shifts from the sleep state to the activated state (step S130), and itself The response signal including the identifier is transmitted to the vehicle-mounted device 1 by the portable transmission unit 53 (step S131).

  The control unit 11 of the in-vehicle device 1 that has transmitted the position detection signal by the process of step S127 determines whether or not the in-vehicle reception unit 13 has received the response signal transmitted from the portable device 5 within a predetermined standby time. Determination is made (step S132). When it determines with having received the response signal (step S132: YES), the control part 11 returns a process to step S117.

  When it is determined that the response signal has not been received (step S132: NO), the control unit 11 determines that the portable device 5 is outside the transmission range around the vehicle, and drives the locking / unlocking unit 6 to The vehicle door is locked (step S133), and the process ends.

According to the vehicle-mounted device 1 and the vehicle communication system configured as described above, by simultaneously transmitting signals from the two LF transmission antennas 10 that are spaced apart from the front and rear of the vehicle C, the signal transmission range is changed to the left and right. Can be expanded. Specifically, as shown in FIG. 5, by transmitting signals of opposite phases simultaneously from the first and second LF transmitting antennas 10a and 10b for the tire air pressure monitoring system disposed before and after the vehicle C. The transmission range of the signal can be expanded to the left and right of the vehicle C. Similarly, the transmission range of the signal can be expanded to the left and right of the vehicle C by simultaneously transmitting opposite-phase signals from the third and fourth LF transmission antennas 10c and 10d. Therefore, the presence / absence of the portable device 5 that is further away from the vehicle C can be detected.
In addition, when there is no response from the portable device 5 with respect to the signals transmitted at the same time, the position detection signal is transmitted from the indoor LF transmission antenna 1a by increasing the transmission intensity, so that the portable device 5 in the dead zone region is also wireless. Communication can be performed, and the portable device 5 within the expanded transmission range can be detected without omission.

  Furthermore, after it stops and a vehicle door opens and closes, when it determines with there being no portable device 5 in the said expanded transmission range, a vehicle door can be locked automatically. In this way, the transmission range of the LF transmission antenna 10 for the tire pressure monitoring system can be expanded to the left and right of the vehicle C to configure an automatic locking system.

  In the present embodiment, the configuration for realizing the locking function using the first to fourth LF transmitting antennas 10a, 10b, 10c, and 10d constituting the tire pressure monitoring system has been described. Needless to say, Smart Entry (registered trademark) is used. In addition, the locking function may be realized by using the LF transmitting antenna 10 that arbitrarily constitutes the system.

  In the present embodiment, the LF transmission antenna 10 is arranged at each tire position. However, the arrangement of the LF transmission antenna 10 is not limited to each tire position. For example, the LF transmission antenna 10 may be arranged at the rear part of the vehicle C in addition to the respective tire positions, and the LF transmission antennas 10 are arranged at three locations on the right side, left side, and rear part of the vehicle C. It may be configured.

  Furthermore, the present invention can be applied not only to an automatic locking system that realizes a locking function, but also to a smart entry (registered trademark) function or any other system that requires communication with the portable device 5.

  Furthermore, in the present embodiment, an example in which the in-vehicle device 1 transmits a signal using radio waves in the LF band has been described, but the signals are transmitted from the two LF transmitting antennas 10 within a range where communication with the portable device 5 is necessary. The frequency of the signal is not particularly limited as long as the signal does not interfere and cancel each other.

  Furthermore, in the present embodiment, an example in which the same signal is simultaneously transmitted from the two LF transmission antennas 10 has been described. Needless to say, the same signal is simultaneously transmitted from three or more LF transmission antennas 10. You may comprise. Further, the position detection signal may be transmitted simultaneously from all the front, rear, left and right LF transmitting antennas 10. In this case, the first and second LF transmission antennas 10a and 10b may transmit opposite phase position detection signals, and the third and fourth LF transmission antennas 10c and 10d may transmit opposite phase position detection signals. In addition, it is preferable to transmit in-phase position detection signals from the first and third LF transmission antennas 10a and 10c and transmit in-phase position detection signals from the second and fourth LF transmission antennas 10b and 10d. In this case, the transmission range can be expanded in the front-rear direction of the vehicle.

  In the present embodiment, the case where the signals transmitted simultaneously from the two LF transmission antennas 10 are the same has been mainly described. However, this is an example, and the signals need not be completely the same. Further, as long as signals transmitted simultaneously from the two LF transmission antennas 10 are superimposed and the amplitude is increased, the phases of the signals may be shifted. Furthermore, the signals transmitted from the two LF transmitting antennas 10 do not need to be transmitted at the same timing, and the transmission timings of the signals may be shifted as long as the signals are superimposed and the amplitude increases.

1 In-vehicle device 1a Indoor LF transmitting antenna (indoor antenna)
DESCRIPTION OF SYMBOLS 2 Detection apparatus 3 Tire 4 Notification apparatus 5 Portable machine 6 Locking / unlocking part 7 Door opening / closing detection switch 8a, 8b, 8c, 8d, 8e Transmission range 8ab (enlarged) transmission range 10 LF transmission antenna (transmission antenna)
10a First LF transmitting antenna (transmitting antenna)
10b Second LF transmitting antenna (transmitting antenna)
10c Third LF transmitting antenna (transmitting antenna)
10d Fourth LF transmit antenna (transmit antenna)
11 Control unit (transmission control unit, indoor transmission control unit, request signal transmission unit, position detection unit, locking control unit)
DESCRIPTION OF SYMBOLS 12 Memory | storage part 12a Control program 13 In-vehicle receiving part 13a RF receiving antenna 14 In-vehicle transmitting part 15 In-vehicle communication part 16 Input part 21 Sensor control part 22 Sensor storage part 23 Sensor transmitting part 23a RF transmitting antenna 24 Sensor receiving part 24a LF receiving antenna 25 Air Pressure Detection Unit 51 Mobile Control Unit 52 Mobile Device Storage Unit 53 Mobile Transmitter 53a RF Transmit Antenna 54 Mobile Receiver 54a LF Receive Antenna 140a First Transmitter 140b Second Transmitter 140c Third Transmitter 140d Fourth Transmitter 140e indoor transmission unit 141a, 141b, 141c, 141d, 141e signal generation circuit 142a, 142b, 142c, 142d phase shift circuit (phase control unit)
143e Strength change part C vehicle

Claims (12)

An in-vehicle device that transmits signals from at least two transmitting antennas that are spaced apart from the front and rear of the vehicle and an indoor antenna that radiates radio waves into the vehicle interior, and performs processing according to a response signal from the portable device that has received the signal Because
A transmission control unit for simultaneously transmitting the signals from the two transmission antennas;
If the response signal is not received from the portable device for the signals transmitted from the two transmission antennas, the signal is transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal. An intensity changing unit for changing the transmission intensity of the signal;
An in-vehicle device comprising: an indoor transmission control unit that transmits the signal from the indoor antenna with the transmission intensity changed by the intensity changing unit. The indoor transmission control unit
Before the signal is transmitted from the two transmission antennas in the transmission control unit, the signal of the first transmission intensity is transmitted from the indoor antenna to the portable device,
The transmission control unit
If the response signal from the portable device with respect to the signal of the first transmission intensity transmitted from the indoor antenna is not received, the signal is transmitted simultaneously from the two transmission antennas,
The indoor transmission control unit
When the response signal is not received from the portable device for the signals transmitted from the two transmission antennas, the portable device outside the vehicle is stronger than the first transmission intensity and can receive the signal. The in-vehicle device according to claim 1, wherein the signal is transmitted from the indoor antenna at a second transmission intensity. The position detection part which detects the position of the said portable machine according to whether the said response signal from the said portable machine with respect to the said signal transmitted by the said transmission control part and the said indoor transmission control part was received. The in-vehicle device according to claim 1 or claim 2. Locking control for controlling locking of the door when the response signal from the portable device to the signal transmitted by the transmission control unit and the indoor transmission control unit is not received after the vehicle door is opened and closed The in-vehicle device according to any one of claims 1 to 3. The in-vehicle device according to any one of claims 1 to 4, wherein the signal in an LF (Low Frequency) band is transmitted from the two transmission antennas and the indoor antenna. The in-vehicle device according to any one of claims 1 to 5, further comprising: a phase control unit that controls a phase of the signal to be transmitted simultaneously from the two transmission antennas. The two transmission antennas have a magnetic core whose axial direction is the front-rear direction in the traveling direction of the vehicle, and a coil whose winding direction with respect to each magnetic core is the same.
The phase control unit
The in-vehicle device according to claim 6, wherein the phase of the signal transmitted from the two transmission antennas spaced apart from each other in the traveling direction of the vehicle is controlled to be opposite in phase. The two transmitting antennas have a magnetic core whose axial direction is the front-rear direction in the traveling direction of the vehicle, and coils whose winding directions with respect to each magnetic core are opposite to each other,
The phase control unit
The in-vehicle device according to claim 6, wherein the phase of the signal transmitted from the two transmission antennas spaced apart from each other in the traveling direction of the vehicle is controlled to be in phase. The transmitting antenna is
Each of the vehicle is disposed at a tire position where a plurality of tires are provided,
Air pressure requesting air pressure information from the transmitting antennas arranged at the respective tire positions to a plurality of detection devices provided on the respective tires and wirelessly transmitting air pressure signals obtained by detecting the air pressure of the tires The in-vehicle device according to any one of claims 1 to 8, further comprising a request signal transmission control unit that transmits an information request signal. The in-vehicle device according to any one of claims 1 to 9,
At least two transmitting antennas spaced apart in front of and behind the vehicle;
An indoor antenna that radiates radio waves into the interior of the vehicle;
A vehicle communication system comprising: a portable device that receives the signal transmitted from the in-vehicle device and transmits a response signal according to the received signal. Communication processing in which signals are transmitted from at least two transmitting antennas arranged in front and rear of the vehicle and an indoor antenna that radiates radio waves into the vehicle interior, and processing is performed according to a response signal from the portable device that has received the signal A method,
Transmitting the signals simultaneously from the two transmit antennas;
If the response signal is not received from the portable device for the signals transmitted from the two transmission antennas, the signal is transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal. Change the transmission strength of the signal,
A communication processing method for transmitting the signal from the indoor antenna at a changed transmission intensity. A signal transmitted from the two transmission antennas and the indoor antenna to an on-vehicle device connected to at least two transmission antennas disposed in front of and behind the vehicle and an indoor antenna that radiates radio waves into the vehicle interior; Is a control program that executes processing according to a response signal from a portable device that has received
Transmitting the signal simultaneously from the two transmit antennas;
If the response signal is not received from the portable device for the signals transmitted from the two transmission antennas, the signal is transmitted from the indoor antenna so that the portable device outside the vehicle can receive the signal. Change the transmission strength of the signal,
A control program for causing the in-vehicle device to execute a process of transmitting the signal from the indoor antenna with the changed transmission intensity.

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