WO2019142656A1 - On-vehicle antenna device - Google Patents

On-vehicle antenna device Download PDF

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Publication number
WO2019142656A1
WO2019142656A1 PCT/JP2019/000012 JP2019000012W WO2019142656A1 WO 2019142656 A1 WO2019142656 A1 WO 2019142656A1 JP 2019000012 W JP2019000012 W JP 2019000012W WO 2019142656 A1 WO2019142656 A1 WO 2019142656A1
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WO
WIPO (PCT)
Prior art keywords
signal
vehicle
antenna
receiving
reception
Prior art date
Application number
PCT/JP2019/000012
Other languages
French (fr)
Japanese (ja)
Inventor
石河　伸一
Original Assignee
株式会社オートネットワーク技術研究所
住友電装株式会社
住友電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 株式会社オートネットワーク技術研究所, 住友電装株式会社, 住友電気工業株式会社 filed Critical 株式会社オートネットワーク技術研究所
Publication of WO2019142656A1 publication Critical patent/WO2019142656A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/24—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H04W4/48—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for in-vehicle communication

Definitions

  • the present invention relates to an on-vehicle antenna device.
  • This application claims the priority based on Japanese Patent Application No. 2018-005668 filed on Jan. 17, 2018, and uses all the contents described in the Japanese application.
  • a communication system for vehicles used for a keyless entry system or a smart entry (registered trademark) system has been proposed.
  • locking and unlocking of the vehicle door are performed by wireless communication between a wireless terminal carried by a passenger and, for example, an on-vehicle control device that controls locking and unlocking of the vehicle door.
  • Patent Document 1 discloses that a glass antenna and a microstrip antenna or a chip-like laminated plate antenna are electrically connected to increase the antenna induced voltage, thereby improving the reception sensitivity and transmission performance.
  • An antenna is disclosed.
  • An on-vehicle antenna device includes a plurality of RF reception antennas that receive an RF reception signal from the outside of a vehicle, wherein the plurality of RF reception antennas receive the RF reception signal.
  • the RF receiving antenna according to any one of the plurality of RF receiving antennas, including one RF receiving antenna, wherein the receiving antenna element is made of a see-through material and has horizontal polarization directivity different from at least one other RF receiving antenna.
  • the vehicle-mounted antenna apparatus of this embodiment is a graph showing the result of having simulated the effect by a capacitor.
  • it is a graph showing the result of having simulated the effect by an inductor and a capacitor.
  • It is a functional block diagram which shows the structure of RF receiving circuit in the vehicle-mounted antenna apparatus of this embodiment. It is a flowchart explaining RF reception processing of the response signal in the in-vehicle antenna device concerning this embodiment.
  • the antenna when the antenna is provided in a hidden place of the vehicle in order to improve the design of the vehicle, there is also a problem that the vehicle may be shielded by the chassis and the like and the signal may not be received from the outside.
  • the present invention has been made in view of such circumstances, and an object of the present invention is to provide an on-vehicle antenna device capable of securing a stable communication state without impairing the vehicle design and the visibility of the driver. It is in.
  • an on-vehicle antenna device capable of improving the directivity gain of the RF receiving antenna and securing a communicable distance while enhancing the degree of freedom in installation of the RF receiving antenna. it can.
  • the on-vehicle antenna device includes a plurality of RF reception antennas for receiving an RF reception signal from the outside of the vehicle.
  • the plurality of RF reception antennas are the RF reception signals.
  • the RF receiving antenna element for receiving comprises one RF receiving antenna whose horizontal polarization directivity is different from that of at least one other RF receiving antenna, and any of the plurality of RF receiving antennas.
  • a selection unit is provided to select an RF reception antenna.
  • the plurality of RF receiving antennas are made of a material through which the RF receiving antenna element can be seen. Therefore, it can mount
  • the selecting unit can select an RF receiving antenna with good reception sensitivity each time.
  • the directions of dips due to the respective horizontal polarization directivity of the one RF receiving antenna and the other RF receiving antenna are different.
  • the selection unit selects any RF receiving antenna in which the direction of dip due to horizontal polarization directivity is different. Therefore, the deterioration of the reception sensitivity due to the dip can be prevented.
  • the respective RF receiving antennas are respectively provided in the windows of the vehicle which are different in the heading direction.
  • each RF receiving antenna is, for example, a front window and a right / left window or a right / left window among the front window (traveling direction of the vehicle), the right / left window, and the back window of the vehicle. , Provided on the back window. Therefore, in each RF receiving antenna, the direction of dip due to horizontal polarization directivity can be made different.
  • the on-vehicle antenna device sends a plurality of LF transmission antennas that transmit an LF transmission signal having a frequency different from that of the RF reception signal, and the LF transmission signal to the LF transmission antenna. And a twisted pair wire receiving the RF reception signal via the RF reception antenna.
  • the twisted pair is shared by the LF transmitting antenna and the RF receiving antenna, and the twisted pair transmits the LF transmitting signal to the LF transmitting antenna, and the RF transmitting antenna is connected via the RF receiving antenna.
  • Receive RF receive signal Therefore, the number of parts can be reduced, the manufacturing cost can be reduced, and the configuration of the apparatus can be made compact.
  • the on-vehicle antenna device includes an LF transmission unit that transmits the LF transmission signal to the LF transmission antenna, and the LF transmission unit includes an inductor that prevents the inflow of the RF reception signal. Have.
  • the LF transmitter that transmits the LF transmission signal has an inductor that prevents the inflow of the RF reception signal. Therefore, it is possible to prevent in advance that the RF reception signal received by the RF reception antenna enters the LF transmission unit via the twisted pair wire and is leaked due to the shared twisted pair wire.
  • the on-vehicle antenna device includes a capacitor that prevents the LF transmission signal from flowing into the RF receiving antenna.
  • the capacitor prevents the LF transmission signal from flowing into the RF receiving antenna in advance. Therefore, it is possible to prevent that the LF transmission signal, which is originally sent to the LF transmission antenna, flows into the RF reception antenna and leaks due to the sharing of the twisted pair wire.
  • FIG. 1 is a schematic view showing an essential configuration of an on-vehicle communication system of a vehicle including the on-vehicle antenna device according to the present embodiment.
  • a symbol V indicates a vehicle
  • a symbol 200 indicates a vehicle-mounted communication system
  • a symbol 100 indicates a vehicle-mounted antenna device according to the present embodiment.
  • the on-vehicle communication system 200 communicates with the wireless terminal R by radio.
  • the radio terminal R is carried by the occupant of the vehicle V, and transmits a radio signal based on the operation of the occupant.
  • the wireless terminal R is used in a so-called keyless entry system, a smart entry system or the like, and is called, for example, a name such as a wireless key or a remote control key.
  • An on-vehicle communication system 200 receives an instruction acceptance signal indicating that an instruction to execute an operation related to a vehicle has been received from the user.
  • the operation related to the vehicle (hereinafter referred to as the vehicle operation) is, for example, locking or unlocking of the door of the vehicle V, start of the engine of the vehicle V, or the like.
  • the instruction acceptance signal is input to the in-vehicle communication system 200.
  • the on-vehicle communication system 200 wirelessly transmits a plurality of request signals (LF transmission signals) for requesting transmission of a response signal (RF reception signal) to the radio terminal R.
  • a request signal is a signal generated by modulating the amplitude of the LF carrier.
  • the wireless terminal R transmits a response signal indicating the signal strength of the received request signal to the in-vehicle communication system 200 by radio.
  • the response signal is also a signal generated by modulating the amplitude or frequency of the RF carrier wave.
  • the data stream of the response signal is composed of a preamble portion (data preamble), a command code, a check bit, and a rolling code for securing the security of the vehicle V in order from the top.
  • the data stream has a fixed length, and the preamble part has a data length of about 100 bits.
  • the transmission bit time (bit rate) of the data stream is transmitted between several Kbps and 20 Kbps.
  • the on-vehicle communication system 200 When receiving the response signal, the on-vehicle communication system 200 detects the position of the wireless terminal R based on the strengths of the request signals (hereinafter referred to as LF signal strength) indicated by the plurality of response signals received from the wireless terminal R. Do. When the detected position of the wireless terminal R is within the predetermined range, the in-vehicle communication system 200 generates an operation instruction signal for instructing execution of a vehicle operation corresponding to the received instruction reception signal to a corresponding device in the vehicle V Output to Thereby, for example, locking or unlocking of the door or starting of the engine is performed.
  • LF signal strength the strengths of the request signals
  • the wireless terminal R can also wirelessly transmit a door signal (RF reception signal) instructing lock or unlock of the door to the on-vehicle communication system 200.
  • the door signal is also a signal generated by modulating the amplitude or frequency of the RF carrier wave.
  • the on-vehicle communication system 200 wirelessly receives a door signal from the wireless terminal R, the on-vehicle communication system 200 outputs an operation instruction signal corresponding to the received door signal to a corresponding device in the vehicle V. Thereby, the door is locked or unlocked.
  • FIG. 2 is a functional block diagram showing an essential configuration of the in-vehicle communication system 200 of the vehicle V according to the present embodiment.
  • the in-vehicle communication system 200 includes an in-vehicle antenna device 100 and a control unit 10.
  • the in-vehicle antenna device 100 includes an LF transmitting device 30 and an RF receiving device 20.
  • the LF transmission device 30 has an LF transmission circuit 31, twisted pair lines A1, A2 and A3, and LF transmission antennas T1, T2 and T3.
  • the RF receiving apparatus 20 includes an RF receiving circuit 21, twisted pair lines A1, A2 and A3, and RF receiving antennas D1, D2 and D3. That is, the twisted pair lines A1, A2 and A3 are shared by the LF transmitter 30 and the RF receiver 20.
  • the in-vehicle communication system 200 includes an output unit 14, an input unit 11, an input / output unit 12, a storage unit 13, and a control unit 10.
  • the output unit 14, the input unit 11, the input / output unit 12, the storage unit 13, and the control unit 10 are connected to the bus 15.
  • each of twisted pair wires A1, A2 and A3 is connected to each of the LF transmitting antennas T1, T2 and T3. Further, RF receiving antennas D1, D2, D3 are further connected to one ends of the twisted pair wires A1, A2, A3.
  • the LF transmission circuit 31 and the RF reception circuit 21 are connected to the other end of each of the twisted pair wires A1, A2 and A3. That is, as described above, the twisted pair lines A1, A2, and A3 are shared by the LF transmission circuit 31 and the RF reception circuit 21.
  • the LF transmission circuit 31 is further connected to the output unit 14.
  • the RF reception circuit 21 is further connected to the input unit 11.
  • the output unit 14 outputs the request signal to the LF transmission circuit 31 in accordance with an instruction from the control unit 10.
  • the LF transmission circuit 31 outputs the request signal to the LF transmission antennas T1, T2 and T3 via the twisted pair lines A1, A2 and A3, respectively.
  • Each of the LF transmission antennas T1, T2 and T3 outputs the input request signal to the radio terminal R by radio. Thereby, a request signal is transmitted to the wireless terminal R.
  • the LF transmission circuit 31 sequentially transmits the request signal to the radio terminal R via the LF transmission antennas T1, T2 and T3 by LF radio. In other words, the LF transmission circuit 31 transmits the request signal to the radio terminal R from the LF transmission antennas T1, T2 and T3 with a time interval. Each time the wireless terminal R receives one request signal, it transmits the response signal indicating the LF signal strength of the received request signal to the on-vehicle communication system 200 by RF radio.
  • a response signal and a door signal are input from the wireless terminal R to the RF receiving antennas D1, D2, and D3.
  • the RF receiving antenna D1, D2, D3 transmits the input response signal or the door signal to the twisted pair A1, A2, A3. It outputs to the RF receiving circuit 21 via
  • the response signal or the door signal input to the RF receiving antennas D1, D2, D3 is received by the RF receiving circuit 21.
  • the RF receiving circuit 21 When the RF receiving circuit 21 receives the response signal, the RF receiving circuit 21 extracts an LF intensity signal indicating the LF signal intensity from the received response signal, and outputs the extracted LF intensity signal to the input unit 11.
  • the LF strength signal is composed of a plurality of bit values.
  • the input unit 11 When the LF intensity signal is input from the RF receiving circuit 21, the input unit 11 notifies the control unit 10 of the LF signal intensity indicated by the input LF intensity signal.
  • the RF reception circuit 21 When the RF reception circuit 21 receives the door signal, the RF reception circuit 21 extracts a content signal indicating an instruction content of the door signal from the received door signal, and outputs the extracted content signal to the input unit 11.
  • the content signal is also composed of a plurality of bit values.
  • the input unit 11 When the content signal is input from the RF reception circuit 21, the input unit 11 notifies the control unit 10 of the instruction content indicated by the input content signal.
  • the instruction acceptance signal is input to the input / output unit 12 from each device in the vehicle V.
  • the input / output unit 12 notifies the control unit 10 of the content indicated by the input instruction acceptance signal. Further, the input / output unit 12 outputs the operation instruction signal instructing execution of the vehicle operation to a corresponding device in the vehicle V according to an instruction of the control unit 10.
  • the storage unit 13 is a non-volatile memory.
  • the storage unit 13 stores a computer program P.
  • the control unit 10 has a CPU (Central Processing Unit) not shown.
  • the CPU of the control unit 10 executes various processes by executing the computer program P.
  • the control unit 10 instructs the output unit 14 to output the request signal to the LF transmission circuit 31.
  • the LF transmission circuit 31 sequentially LF-transmits three request signals to the radio terminal R at time intervals via the LF transmission antennas T1, T2 and T3.
  • the wireless terminal R transmits the response signal to the on-vehicle communication system 200 by RF.
  • the RF receiving circuit 21 outputs the LF intensity signal according to the received response signal to the input unit 11. Do.
  • the control unit 10 detects the position of the wireless terminal R based on the plurality of strengths indicated by the LF strength signals. When the detected position of the wireless terminal R is within the predetermined range, the control unit 10 instructs the input / output unit 12 to output the operation instruction signal to a predetermined device in the vehicle V corresponding to the instruction reception signal. Thereby, for example, locking or unlocking of the door or starting of the engine is performed.
  • the control unit 10 instructs the input / output unit 12 And an operation instruction signal is output to a device corresponding to the door signal in the vehicle V. Thereby, the door is locked or unlocked.
  • the frequency band of the request signal is different from the frequency band of the response signal and the door signal.
  • the frequency band of the request signal is low, and the frequency band of the response signal and the door signal is high.
  • the frequency band of the request signal is, for example, an LF band included in the range of 100 kHz to 200 kHz.
  • the frequency band of each of the response signal and the door signal is, for example, an RF (UHF) band included in the range of 300 MHz to 400 MHz.
  • the LF transmitting antennas T1, T2 and T3 are respectively disposed in the vicinity of the right door, in the vicinity of the left door, and in the rear luggage in the traveling direction of the vehicle V.
  • the LF transmitter 30 and the RF receiver 20 share the twisted pair lines A1, A2, and A3. Therefore, the LF transmission antennas T1, T2 and T3 and the RF reception antennas D1, D2 and D3 are provided in the vicinity of each other.
  • the number of parts can be reduced, and the configuration can be simplified.
  • FIG. 3 is an exemplary view for explaining the arrangement of the RF receiving antennas D1, D2, and D3 in the on-vehicle antenna device 100 of the present embodiment.
  • the RF receiving antennas D1, D2, and D3 are respectively provided on the right side window, the left side window, and the rear side window of the vehicle V.
  • the RF receiving antenna D1 will be described as an example.
  • the RF receiving antenna D1 is attached to the right window W of the vehicle V, and the LF transmitting antenna T1 is provided on the right door RD of the vehicle V as described above (not shown).
  • the RF receiving antenna D1 is a UHF band dipole antenna that can correspond to the response signal and the door signal.
  • antenna elements 25a and 25b (RF receiving antenna elements) for receiving the response signal and the door signal form an L shape.
  • the antenna elements 25a, 25b are made of a film-like see-through material.
  • the term "visible" includes a transparent state, and may have a predetermined visible light transmittance (for example, 80% or more).
  • the antenna elements 25a and 25b are made of FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), AZO (ZnO: Al), GZO (ZnO: Ga) or the like.
  • the other RF receiving antennas D2 and D3 are the same as the RF receiving antenna D1, and the detailed description will be omitted.
  • the RF receiving antennas D1, D2, and D3 are respectively provided on the right side window, the left side window, and the rear side window of the vehicle V.
  • the right side window faces the right side of the vehicle V
  • the left side window faces the left side of the vehicle V
  • the rear side faces the rear side of the vehicle V. Therefore, the RF receiving antennas D1, D2 and D3 are respectively provided in windows having different directions.
  • the RF receiving antennas D1, D2 and D3 are provided in a hidden place of the vehicle V in consideration of the design of the vehicle V, they are shielded by the chassis etc., and the response signal and the door signal etc. There is a case that can not be received.
  • the RF receiving antennas D1, D2, and D3 are thus provided in the window of the vehicle V, the vehicle design and the driver's visibility are improved. It is possible to increase the reception rate without harming the reception of the response signal and the door signal and the like.
  • the RF receiving antennas D1, D2, D3 have horizontal polarization directivity.
  • the horizontal polarization directivity is a characteristic in which the signal strength (field strength) representing the reception sensitivity is distributed horizontally, and the directivity of the antenna, that is, the sensing area becomes horizontal.
  • the horizontal polarization directivity of the RF receiving antennas D1 and D2 (one RF receiving antenna) and the RF receiving antenna D3 (another RF receiving antenna) are different. Specifically, the directions of dips (hereinafter simply referred to as dips) due to horizontal polarization directivity differ from each other between the RF receiving antennas D1 and D2 and the RF receiving antenna D3.
  • FIG. 4 is a graph showing the gain of the horizontal polarization directivity of the RF receiving antennas D1, D2, and D3 in the on-vehicle antenna device 100 of the present embodiment.
  • FIG. 4A shows the horizontal polarization directivity of the RF reception antenna D3 of the rear window of the vehicle V
  • FIG. 4B shows the horizontal polarization directivity of the RF reception antennas D1 and D2 of the right and left windows of the vehicle V It shows.
  • the directions of dips S2 of the RF receiving antennas D1 and D2 (right and left windows) of FIG. 4B are different from the directions of the dips S2 of the RF receiving antenna D3 (rear side window) of FIG. 4A.
  • the direction of dip S2 is the direction from the RF receiving antenna located at the center of the circle. In the present embodiment, the direction of the dip S2 of the RF receiving antenna D3 is 90.degree.
  • the directions of dips S2 of the RF receiving antennas D1 and D2 are 0 ° and 180 °.
  • the directions of the dips S2 of the RF receiving antenna D3 and the RF receiving antennas D1 and D2 are configured such that the insensitive regions due to the respective dips S2 do not overlap.
  • the dead zones in the RF receiving antenna D3 and the RF receiving antennas D1 and D2 can be mutually compensated. That is, by selecting any RF receiving antenna not affected by the dip S2, a failure due to the dip S2 can be prevented, and a communicable area and a stable communication state can be secured.
  • the present embodiment is not limited to this.
  • the dip directions of the RF receiving antenna D1, the RF receiving antenna D2, and the RF receiving antenna D3 may be different from each other.
  • FIG.5 and FIG.6 is a schematic circuit diagram which shows the structure of the vehicle-mounted antenna apparatus 100 of this embodiment.
  • FIG. 5 shows the side of the RF reception antennas D1, D2, D3 and the LF transmission antennas T1, T2, T3 with respect to the twisted pair lines A1, A2, A3 in the on-vehicle antenna device 100.
  • FIG. 6 shows the side of the LF transmission circuit 31 and the RF reception circuit 21 with respect to the twisted pair lines A1, A2 and A3.
  • the RF receiving antenna D1 and the LF transmitting antenna T1 will be described as an example, and the RF receiving antenna D2 and the LF transmitting antenna T2, and the RF receiving antenna D3 and the LF transmitting antenna T3 will be described. Detailed explanation is omitted.
  • Each of the antenna elements 25a and 25b of the RF receiving antenna D1 has a dipole antenna shape which is disposed symmetrically to each other as shown in FIG.
  • One end of the capacitor C1 is connected to one end of the antenna element 25a.
  • one end of the capacitor C2 is connected to one end of the antenna element 25b.
  • the impedance of the capacitors C1 and C2 is, for example, 100 pF.
  • the twisted pair wire A1 has two conducting wires 26a and 26b which are twisted together.
  • the other end of each of the capacitors C1 and C2 of the RF receiving antenna D1 is connected to one end of the conducting wire 26a and 26b.
  • the other ends of the conductors 26 a and 26 b are connected to the LF transmitter circuit 31 and the RF receiver circuit 21.
  • One end of the conducting wire 26a, 26b is disposed near one end of the twisted pair wire A1, and the other end of the conducting wire 26a, 26b is disposed near the other end of the twisted pair wire A1.
  • the input response signal (or door signal) is transmitted from the other end of the two capacitors C1 and C2 to the two conductors 26a and 26b of the twisted pair A1.
  • a balanced signal that is, a signal indicated by a voltage difference between the two conductors 26a and 26b.
  • the LF transmission antenna T1 is a so-called bar coil antenna having a coil 27.
  • the inductance of the coil 27 is, for example, 350 to 780 ⁇ H.
  • One end of the coil 27 is connected to one end of the conducting wire 26a.
  • the other end of the coil 27 is connected to one end of the conducting wire 26b.
  • the other end of the capacitor C1 is connected to the contact between the coil 27 and the lead 26a, and the other end of the capacitor C2 is connected to the contact between the other end of the coil 27 and the lead 26b.
  • the LF transmission antenna T1 outputs the request signal output from the LF transmission circuit 31 to the radio terminal R via the twisted pair wire A1.
  • the absolute value of the impedance of each of the capacitors C1 and C2 is large for the request signal having a low frequency band and small for the response signal and the door signal having a high frequency band. That is, the capacitors C1 and C2 prevent the request signal output from the LF transmission circuit 31 through the twisted pair line A1 from being output from the RF receiving antenna D1 to the outside.
  • the absolute value of the impedance of the coil 27 is smaller for the request signal having a lower frequency band and larger for the response signal and the door signal having a higher frequency band. That is, the coil 27 prevents the response signal and the door signal received by the RF receiving antenna D1 from being output from the LF transmitting antenna T1 to the outside.
  • FIG. 7 is a graph showing the simulation result of the effects of the capacitors C1 and C2 in the on-vehicle antenna device 100 of the present embodiment.
  • the loss due to the leakage by the coil 27 can be reduced to about 0.011 dB or less for the response signal and the door signal.
  • the loss due to the leakage by the RF receiving antenna D1 can be made about -44.4 dB or less.
  • the LF transmission circuit 31 includes a drive unit 32 and inductors 33a and 33b.
  • the drive unit 32 outputs the request signal.
  • One end of the inductor 33a is connected to the other end side of the conducting wire 26a of the twisted pair wire A1.
  • One end of the inductor 33b is connected to the other end side of the conductor 26b of the twisted pair wire A1.
  • the other ends of the inductors 33 a and 33 b are connected to the drive unit 32.
  • the inductance of the inductors 33a and 33b is, for example, 1 ⁇ H.
  • the absolute value of the impedance of the inductors 33a and 33b is larger than the response signal and the door signal whose frequency band is high. Therefore, the inductors 33a and 33b prevent the response signal and the door signal received by the RF receiving antenna D1 from being input to the driving unit 32.
  • the RF reception circuit 21 has a conversion circuit 28 and capacitors C3 and C4. One end of the capacitor C3 is connected to the other end side of the conducting wire 26a of the twisted pair wire A1. One end of the capacitor C4 is connected to the other end side of the conducting wire 26b of the twisted pair wire A1. The other ends of the capacitors C3 and C4 are connected to the conversion circuit 28.
  • the conversion circuit 28 is further connected to an extraction unit 23 described later via a switching unit 22 described later.
  • the extraction unit 23 is further connected to the input unit 11.
  • the conversion circuit 28 is grounded.
  • the conversion circuit 28 converts the input balanced response signal into an unbalanced response signal based on the ground potential, and outputs the converted response signal to the extraction unit 23.
  • An unbalanced signal is a signal referenced to a fixed potential, eg, ground potential.
  • the balanced response signal and the door signal are input from the RF receiving antenna D1 via the twisted pair wire A1, and the translating circuit 28 receives the unbalanced response signal and the door signal as an unbalanced response signal and the door signal. And output to the extraction unit 23.
  • the absolute values of the inductances of the capacitors C3 and C4 are large for the request signal having a low frequency band and small for the response signal and the door signal having a high frequency band. Therefore, the capacitors C3 and C4 prevent the request signal output from the LF transmission circuit 31 to the LF transmission antenna T1 from being input to the conversion circuit 28.
  • FIG. 8 is a graph showing the simulation result of the effects of the inductors 33a and 33b and the capacitors C3 and C4 in the on-vehicle antenna device 100 of the present embodiment.
  • the loss due to the leakage by the drive unit 32 can be made 0.01 dB for the response signal and the door signal.
  • the capacitors C3 and C4 the loss due to the leakage by the conversion circuit 28 can be made about -49.6 dB or less with respect to the request signal.
  • FIG. 9 is a functional block diagram showing the configuration of the RF receiving circuit 21 in the on-vehicle antenna device 100 of the present embodiment.
  • the display of the capacitors C3 and C4 is omitted.
  • the RF reception circuit 21 includes a switching unit 22 (selection unit) and an extraction unit 23 in addition to the conversion circuit 28 and the capacitors C3 and C4.
  • the RF receiving circuit 21 has, for example, three conversion circuits 28. As described above, the capacitors C3 and C4 are provided for each of the conversion circuits 28.
  • the response signal or the door signal converted into the unbalanced signal by the three conversion circuits 28 is sent to the switching unit 22, and any response signal and the door signal are sent to the extraction unit 23.
  • the switching unit 22 is interposed between the three conversion circuits 28 and the extraction unit 23.
  • Each conversion circuit 28 is connected by a single lead 24 a, 24 b, 24 c, and an unbalanced response signal or door signal is input to the switching unit 22 through the leads 24 a, 24 b, 24 c.
  • the switching unit 22 switches the connection to any one of the conductors 24a, 24b, and 24c at a predetermined cycle.
  • the switching unit 22 can select any one of the RF receiving antennas D1, D2, and D3.
  • the predetermined cycle is set according to the transmission bit time of the response signal to be transmitted from the wireless terminal R. For example, when the predetermined period of switching is set by the time for acquiring 5 bits in the preamble unit, if the bit time is 2 kbps, the switching unit 22 performs the switching at an interval of 2.5 milliseconds.
  • the control unit 10 compares signal strengths (hereinafter referred to as RF signal strengths) related to response signals received through the RF receiving antennas D1, D2, and D3. Then, a switching control signal for selecting the strongest RF signal strength and selecting an RF receiving antenna corresponding to the selected RF signal strength is output to the switching unit 22.
  • RF signal strengths signal strengths
  • the switching unit 22 stops switching at a predetermined cycle, and switching of connection to any one of the conductors 24a, 24b, 24c is performed based on the switching control signal.
  • the extraction unit 23 extracts an RF intensity signal indicating the RF signal intensity from the unbalanced response signal or door signal from the lead wire connected by the switching unit 22, and outputs the extracted RF intensity signal to the input unit 11.
  • FIG. 10 is a flowchart for explaining the reception process of the response signal in the on-vehicle antenna device 100 according to the present embodiment.
  • the control unit 10 constantly executes the processing procedure described below.
  • the control unit 10 waits for a response signal received by any of the RF receiving antennas D1, D2, and D3 for a predetermined period.
  • the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S101). ).
  • the control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D1 in the storage unit 13 in association with each other.
  • control unit 10 outputs, to the switching unit 22, a switching control signal indicating that the connection is switched to the RF receiving antenna D2, that is, the lead 24b.
  • the switching unit 22 switches the connection from the conducting wire 24 a to the conducting wire 24 b based on the switching control signal.
  • the control unit 10 waits for a response signal received by the RF receiving antenna D2 for a predetermined period.
  • the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S102).
  • the control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D2 in the storage unit 13 in association with each other.
  • control unit 10 outputs, to the switching unit 22, a switching control signal indicating that the connection is switched to the RF receiving antenna D3, that is, the lead 24c.
  • the switching unit 22 switches the connection from the lead 24b to the lead 24c based on the switching control signal.
  • the control unit 10 waits for a response signal received by the RF receiving antenna D3 for a predetermined period.
  • the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S103).
  • the control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D3 in the storage unit 13 in association with each other.
  • the control unit 10 outputs, to the switching unit 22, a switching control signal to switch the connection to the RF receiving antenna D1, that is, the lead 24a.
  • the switching unit 22 switches the connection from the conducting wire 24c to the conducting wire 24a based on the switching control signal. Then, the control unit 10 returns to the process of step S101.
  • control unit 10 reads the RF signal strengths stored in the storage unit 13, compares the respective RF signal strengths (step S104), and determines which RF signal strength is the strongest (step S105). .
  • the control unit 10 controls the switching control signal to switch the connection to the RF receiving antenna D1, that is, the lead 24a.
  • the switching unit 22 switches the connection to the conductor 24 a based on the switching control signal.
  • the switching by the switching unit 22 maintains the connection between the RF receiving circuit 21 and the RF receiving antenna D1 that receives the response signal with the highest RF signal strength. Therefore, stable reception of response signals without influence of dip due to horizontal polarization directivity can be performed through the RF receiving antenna D1.
  • the RF receiving circuit 21 receives a response signal from the wireless terminal R via the RF receiving antenna D1, performs demodulation processing of a command code and the like received after the preamble unit, and outputs the result to the control unit 10 (step S107). . Based on the command code, the control unit 10 outputs the operation instruction signal to each device such as a door lock device, a door mirror device, an interior light, a hazard lamp, etc. via the input / output unit 12 (step S108).
  • the case where the response signal can not be received by any of the RF receiving antennas and the RF signal strength can not be obtained may occur.
  • the wireless terminal R which has transmitted such a response signal is located in the dead zone of the RF receiving antenna. Therefore, stable communication can be ensured by switching to any other RF receiving antenna.
  • the on-vehicle antenna device 100 of the present embodiment mutually complements the dead area due to the dips S2 of the respective RF receiving antennas D1, D2 and D3, secures a stable communication state, and stably responds Can be received.

Abstract

An on-vehicle antenna device (100) is provided with a plurality of RF reception antennas (D1, D2, D3) that receive an RF reception signal from the outside of a vehicle (V), wherein: the RF reception antennas (D1, D2, D3) include first RF reception antennas (D1, D2) that each have an RF reception antenna element for receiving the RF reception signal, the RF reception antenna element being made of see-through material, and that is different, in terms of the horizontal polarization orientation, from at least another one of the RF reception antennas (D3); and a selection unit which selects one of the RF reception antennas (D1, D2, D3) is provided.

Description

車載アンテナ装置Car antenna system
　本発明は、車載アンテナ装置に関する。
　本出願は、２０１８年１月１７日出願の日本出願第２０１８－００５６６８号に基づく優先権を主張し、前記日本出願に記載された全ての記載内容を援用するものである。 The present invention relates to an on-vehicle antenna device.
This application claims the priority based on Japanese Patent Application No. 2018-005668 filed on Jan. 17, 2018, and uses all the contents described in the Japanese application.
　従来、キーレスエントリーシステム又はスマートエントリー（登録商標）システム等に用いられる車両用通信システムが提案されている。このような車両用通信システムでは、乗員が所持する無線端末と、例えば、車両ドアの施錠及び解錠を制御する車載制御装置とが無線通信することによって、車両ドアの施錠及び解錠を行う。 Conventionally, a communication system for vehicles used for a keyless entry system or a smart entry (registered trademark) system has been proposed. In such a communication system for a vehicle, locking and unlocking of the vehicle door are performed by wireless communication between a wireless terminal carried by a passenger and, for example, an on-vehicle control device that controls locking and unlocking of the vehicle door.
　一方、特許文献１には、ガラスアンテナと、マイクロストリップアンテナ又はチップ状の積層板状アンテナを電気的に接続し、アンテナ誘起電圧を高めることにより、受信感度、送信性能を向上させる自動車用高周波ガラスアンテナが開示されている。 On the other hand, Patent Document 1 discloses that a glass antenna and a microstrip antenna or a chip-like laminated plate antenna are electrically connected to increase the antenna induced voltage, thereby improving the reception sensitivity and transmission performance. An antenna is disclosed.
特開Ｈ１１－１７４２８号公報JP H11-17428
　本開示の一態様に係る車載アンテナ装置は、車両の外部からＲＦ受信信号を受信する複数のＲＦ受信アンテナを備える車載アンテナ装置において、前記複数のＲＦ受信アンテナは、前記ＲＦ受信信号を受信するＲＦ受信アンテナ素子が透視可能材料からなり、少なくとも一つの他のＲＦ受信アンテナと水平偏波指向性が異なる、一のＲＦ受信アンテナを含み、前記複数のＲＦ受信アンテナのうち、何れかのＲＦ受信アンテナを選択する選択部を備える。 An on-vehicle antenna device according to an aspect of the present disclosure includes a plurality of RF reception antennas that receive an RF reception signal from the outside of a vehicle, wherein the plurality of RF reception antennas receive the RF reception signal. The RF receiving antenna according to any one of the plurality of RF receiving antennas, including one RF receiving antenna, wherein the receiving antenna element is made of a see-through material and has horizontal polarization directivity different from at least one other RF receiving antenna. And a selection unit for selecting
本実施形態に係る車載アンテナ装置を備える車両の車載通信システムの要部構成を示す模式図である。It is a schematic diagram which shows the principal part structure of the vehicle-mounted communication system of a vehicle provided with the vehicle-mounted antenna apparatus which concerns on this embodiment. 本実施形態に係る車両の車載通信システムの要部構成を示す機能ブロックである。It is a functional block which shows the principal part structure of the vehicle-mounted communication system of the vehicle which concerns on this embodiment. 本実施形態の車載アンテナ装置における、ＲＦ受信アンテナの配置を説明する例示図である。It is an illustration figure explaining arrangement | positioning of RF receiving antenna in the vehicle-mounted antenna apparatus of this embodiment. 本実施形態の車載アンテナ装置におけるＲＦ受信アンテナの水平偏波指向性の利得を示すグラフである。It is a graph which shows the gain of horizontal polarization directivity of the RF receiving antenna in the vehicle-mounted antenna apparatus of this embodiment. 本実施形態の車載アンテナ装置の構成を示す概略的回路図である。It is a schematic circuit diagram showing composition of an in-vehicle antenna device of this embodiment. 本実施形態の車載アンテナ装置の構成を示す概略的回路図である。It is a schematic circuit diagram showing composition of an in-vehicle antenna device of this embodiment. 本実施形態の車載アンテナ装置において、キャパシタによる効果をシミュレーションした結果を表すグラフである。In the vehicle-mounted antenna apparatus of this embodiment, it is a graph showing the result of having simulated the effect by a capacitor. 本実施形態の車載アンテナ装置において、インダクタ及びキャパシタによる効果をシミュレーションした結果を表すグラフである。In the vehicle-mounted antenna apparatus of this embodiment, it is a graph showing the result of having simulated the effect by an inductor and a capacitor. 本実施形態の車載アンテナ装置における、ＲＦ受信回路の構成を示す機能ブロック図である。It is a functional block diagram which shows the structure of RF receiving circuit in the vehicle-mounted antenna apparatus of this embodiment. 本実施形態に係る車載アンテナ装置における応答信号のＲＦ受信処理を説明するフローチャートである。It is a flowchart explaining RF reception processing of the response signal in the in-vehicle antenna device concerning this embodiment.
[本開示が解決しようとする課題]
　水平偏波指向性を有するアンテナの場合、水平方向において受信感度（電界強度／ＲＳＳＩ）が著しく低下するいわゆるディップが存在し、前記ディップに起因する不感領域が生じるという問題がある。 [Problems to be solved by the present disclosure]
In the case of an antenna having horizontal polarization directivity, there is a so-called dip in which the reception sensitivity (field strength / RSSI) is significantly reduced in the horizontal direction, and there is a problem that a dead zone resulting from the dip occurs.
　また、車両デザイン性を良くするために、アンテナが車両の隠れた場所に設けられた場合は、車台などに遮蔽され、外部から信号の受信が出来なくなる場合があるという問題もある。 In addition, when the antenna is provided in a hidden place of the vehicle in order to improve the design of the vehicle, there is also a problem that the vehicle may be shielded by the chassis and the like and the signal may not be received from the outside.
　本発明は斯かる事情に鑑みてなされたものであり、その目的とするところは、車両デザイン性及び運転者の視認性を害することなく、安定した通信状態を確保できる車載アンテナ装置を提供することにある。 The present invention has been made in view of such circumstances, and an object of the present invention is to provide an on-vehicle antenna device capable of securing a stable communication state without impairing the vehicle design and the visibility of the driver. It is in.
[本開示の効果]
　本開示の一態様によれば、ＲＦ受信アンテナの設置における自由度を高めつつ、前記ＲＦ受信アンテナの指向性利得を改善でき、通信可能距離を確保することができる車載アンテナ装置を提供することができる。 [Effect of the present disclosure]
According to one aspect of the present disclosure, it is possible to provide an on-vehicle antenna device capable of improving the directivity gain of the RF receiving antenna and securing a communicable distance while enhancing the degree of freedom in installation of the RF receiving antenna. it can.
[本発明の実施形態の説明]
　最初に本開示の実施態様を列挙して説明する。また、以下に記載する実施形態の少なくとも一部を任意に組み合わせてもよい。 Description of the embodiment of the present invention
First, the embodiments of the present disclosure will be listed and described. In addition, at least part of the embodiments described below may be arbitrarily combined.
（１）本開示の一態様に係る車載アンテナ装置は、車両の外部からＲＦ受信信号を受信する複数のＲＦ受信アンテナを備える車載アンテナ装置において、前記複数のＲＦ受信アンテナは、前記ＲＦ受信信号を受信するＲＦ受信アンテナ素子が透視可能材料からなり、少なくとも一つの他のＲＦ受信アンテナと水平偏波指向性が異なる、一のＲＦ受信アンテナを含み、前記複数のＲＦ受信アンテナのうち、何れかのＲＦ受信アンテナを選択する選択部を備える。 (1) In the on-vehicle antenna device according to an aspect of the present disclosure, the on-vehicle antenna device includes a plurality of RF reception antennas for receiving an RF reception signal from the outside of the vehicle. The plurality of RF reception antennas are the RF reception signals. The RF receiving antenna element for receiving comprises one RF receiving antenna whose horizontal polarization directivity is different from that of at least one other RF receiving antenna, and any of the plurality of RF receiving antennas. A selection unit is provided to select an RF reception antenna.
　本態様にあっては、前記複数のＲＦ受信アンテナは前記ＲＦ受信アンテナ素子が透視可能材料からなる。従って、車両デザイン性及び運転者の視認性を害することなく装着でき、車載アンテナ装置の搭載場所の自由度を高めることができる。
　また、前記選択部が、水平偏波指向性の異なる何れかのＲＦ受信アンテナを選択することにより、その都度、受信感度の良いＲＦ受信アンテナを選択できる。 In this aspect, the plurality of RF receiving antennas are made of a material through which the RF receiving antenna element can be seen. Therefore, it can mount | wear without impairing a vehicle design and driver | operator's visibility, and the freedom degree of the mounting location of a vehicle-mounted antenna apparatus can be raised.
In addition, by selecting any one of the RF receiving antennas having different horizontal polarization directivity, the selecting unit can select an RF receiving antenna with good reception sensitivity each time.
（２）本開示の一態様に係る車載アンテナ装置は、前記一のＲＦ受信アンテナと、前記他のＲＦ受信アンテナは、夫々の水平偏波指向性によるディップの方向が異なる。 (2) In the on-vehicle antenna device according to an aspect of the present disclosure, the directions of dips due to the respective horizontal polarization directivity of the one RF receiving antenna and the other RF receiving antenna are different.
　本態様にあっては、水平偏波指向性によるディップの方向が異なる何れかのＲＦ受信アンテナを前記選択部が選択する。従って、ディップによる受信感度の劣化を防止することができる。 In this aspect, the selection unit selects any RF receiving antenna in which the direction of dip due to horizontal polarization directivity is different. Therefore, the deterioration of the reception sensitivity due to the dip can be prevented.
（３）本開示の一態様に係る車載アンテナ装置は、各ＲＦ受信アンテナは、向かう方向が異なる前記車両の窓に夫々設けられている。 (3) In the on-vehicle antenna device according to one aspect of the present disclosure, the respective RF receiving antennas are respectively provided in the windows of the vehicle which are different in the heading direction.
　本態様にあっては、各ＲＦ受信アンテナは、前記車両の前側（車両の進行方向）窓、右・左側窓、裏側窓のうち、例えば、前側窓及び右・左側窓、又は右・左側窓、裏側窓に設けられる。従って、各ＲＦ受信アンテナにおいて、水平偏波指向性によるディップの方向を異ならせることができる。 In this aspect, each RF receiving antenna is, for example, a front window and a right / left window or a right / left window among the front window (traveling direction of the vehicle), the right / left window, and the back window of the vehicle. , Provided on the back window. Therefore, in each RF receiving antenna, the direction of dip due to horizontal polarization directivity can be made different.
（４）本開示の一態様に係る車載アンテナ装置は、前記ＲＦ受信信号と周波数が異なるＬＦ送信信号を外部に送信する複数のＬＦ送信アンテナと、前記ＬＦ送信アンテナに前記ＬＦ送信信号を送り、かつ、前記ＲＦ受信アンテナを介して前記ＲＦ受信信号を受けるツイストペア線とを備える。 (4) The on-vehicle antenna device according to an aspect of the present disclosure sends a plurality of LF transmission antennas that transmit an LF transmission signal having a frequency different from that of the RF reception signal, and the LF transmission signal to the LF transmission antenna. And a twisted pair wire receiving the RF reception signal via the RF reception antenna.
　本態様にあっては、前記ツイストペア線が前記ＬＦ送信アンテナ及び前記ＲＦ受信アンテナに共有され、前記ツイストペア線が前記ＬＦ送信アンテナに前記ＬＦ送信信号を送り、かつ、前記ＲＦ受信アンテナを介して前記ＲＦ受信信号を受ける。従って、部品の点数を減らし、製造コストの削減及び装置の構成をコンパクト化することができる。 In this aspect, the twisted pair is shared by the LF transmitting antenna and the RF receiving antenna, and the twisted pair transmits the LF transmitting signal to the LF transmitting antenna, and the RF transmitting antenna is connected via the RF receiving antenna. Receive RF receive signal. Therefore, the number of parts can be reduced, the manufacturing cost can be reduced, and the configuration of the apparatus can be made compact.
（５）本開示の一態様に係る車載アンテナ装置は、前記ＬＦ送信アンテナに前記ＬＦ送信信号を送信するＬＦ送信部を備え、前記ＬＦ送信部は、前記ＲＦ受信信号の流入を防止するインダクタを有する。 (5) The on-vehicle antenna device according to an aspect of the present disclosure includes an LF transmission unit that transmits the LF transmission signal to the LF transmission antenna, and the LF transmission unit includes an inductor that prevents the inflow of the RF reception signal. Have.
　本態様にあっては、前記ＬＦ送信信号を送信するＬＦ送信部が、前記ＲＦ受信信号の流入を防止するインダクタを有する。従って、前記ツイストペア線が共有されることが原因で、前記ＲＦ受信アンテナが受信したＲＦ受信信号が前記ツイストペア線を介して前記ＬＦ送信部に入って漏洩が生じることを未然に防止できる。 In this aspect, the LF transmitter that transmits the LF transmission signal has an inductor that prevents the inflow of the RF reception signal. Therefore, it is possible to prevent in advance that the RF reception signal received by the RF reception antenna enters the LF transmission unit via the twisted pair wire and is leaked due to the shared twisted pair wire.
（６）本開示の一態様に係る車載アンテナ装置は、前記ＬＦ送信信号が前記ＲＦ受信アンテナに流入することを防止するキャパシタを有する。 (6) The on-vehicle antenna device according to an aspect of the present disclosure includes a capacitor that prevents the LF transmission signal from flowing into the RF receiving antenna.
　本態様にあっては、前記キャパシタが、前記ＬＦ送信信号が前記ＲＦ受信アンテナに流入することを事前に防止する。従って、本来なら前記ＬＦ送信アンテナに送られるＬＦ送信信号が、前記ツイストペア線が共有されることが原因で、前記ＲＦ受信アンテナに流入して漏洩が生じることを防止できる。 In this aspect, the capacitor prevents the LF transmission signal from flowing into the RF receiving antenna in advance. Therefore, it is possible to prevent that the LF transmission signal, which is originally sent to the LF transmission antenna, flows into the RF reception antenna and leaks due to the sharing of the twisted pair wire.
[本発明の実施形態の詳細]
　本発明をその実施形態を示す図面に基づいて具体的に説明する。本開示の実施形態に係る車載アンテナ装置を、以下に図面を参照しつつ説明する。なお、本発明はこれらの例示に限定されるものではなく、請求の範囲によって示され、請求の範囲と均等の意味及び範囲内でのすべての変更が含まれることが意図される。 Details of the Embodiment of the Present Invention
The present invention will be specifically described based on the drawings showing the embodiments. An on-vehicle antenna device according to an embodiment of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these exemplifications, but is shown by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.
　図１は、本実施形態に係る車載アンテナ装置を備える車両の車載通信システムの要部構成を示す模式図である。図１において、符号Ｖは車両を示し、符号２００は車載通信システムを示し、符号１００は本実施形態に係る車載アンテナ装置を示す。車載通信システム２００は無線端末Ｒと無線にて通信を行う。 FIG. 1 is a schematic view showing an essential configuration of an on-vehicle communication system of a vehicle including the on-vehicle antenna device according to the present embodiment. In FIG. 1, a symbol V indicates a vehicle, a symbol 200 indicates a vehicle-mounted communication system, and a symbol 100 indicates a vehicle-mounted antenna device according to the present embodiment. The on-vehicle communication system 200 communicates with the wireless terminal R by radio.
　無線端末Ｒは、車両Ｖの乗員が携帯し、乗員の操作に基づき、無線信号を送信する。無線端末Ｒは、いわゆるキーレスエントリーシステム又はスマートエントリーシステム等にて用いられるものであり、例えば無線キー又はリモコンキー等の名称で呼ばれるものである。 The radio terminal R is carried by the occupant of the vehicle V, and transmits a radio signal based on the operation of the occupant. The wireless terminal R is used in a so-called keyless entry system, a smart entry system or the like, and is called, for example, a name such as a wireless key or a remote control key.
　車載通信システム２００には、車両に関する動作の実行指示を使用者から受け付けたことを示す指示受付信号が入力される。車両に関する動作（以下、車両動作と言う）は、例えば、車両Ｖのドアのロック若しくはアンロック、又は、車両Ｖのエンジンの始動等である。例えば、ドアを開けるためのドアノブのボタンが操作された場合、又は、エンジン始動のためのボタンが操作された場合に前記指示受付信号が車載通信システム２００に入力される。 An on-vehicle communication system 200 receives an instruction acceptance signal indicating that an instruction to execute an operation related to a vehicle has been received from the user. The operation related to the vehicle (hereinafter referred to as the vehicle operation) is, for example, locking or unlocking of the door of the vehicle V, start of the engine of the vehicle V, or the like. For example, when the button of the doorknob for opening the door is operated, or when the button for starting the engine is operated, the instruction acceptance signal is input to the in-vehicle communication system 200.
　車載通信システム２００は、前記指示受付信号が入力された場合、応答信号（ＲＦ受信信号）の送信を要求する複数の要求信号（ＬＦ送信信号）を無線端末Ｒに無線で送信する。斯かる要求信号は、ＬＦ搬送波の振幅を変調することによって生成される信号である。無線端末Ｒは、車載通信システム２００から要求信号を受信する都度、受信した要求信号の信号強度を示す応答信号を車載通信システム２００に無線でＲＦ送信する。 When the instruction acceptance signal is input, the on-vehicle communication system 200 wirelessly transmits a plurality of request signals (LF transmission signals) for requesting transmission of a response signal (RF reception signal) to the radio terminal R. Such a request signal is a signal generated by modulating the amplitude of the LF carrier. Each time the wireless terminal R receives a request signal from the in-vehicle communication system 200, the wireless terminal R transmits a response signal indicating the signal strength of the received request signal to the in-vehicle communication system 200 by radio.
　前記応答信号も、ＲＦ搬送波の振幅又は周波数等を変調することによって生成される信号である。前記応答信号のデータストリームは、先頭から順に、プリアンブル部（データプリアンブル）、コマンドコード、チェックビット及び車両Ｖのセキュリティを確保するローリングコードで構成されている。データストリームは固定長であり、このうちプリアンブル部は、１００ｂｉｔ程度のデータ長をもっている。データストリームの送信ビット時間（ビットレート）は、数Ｋｂｐｓから２０Ｋｂｐｓの間で送信される。 The response signal is also a signal generated by modulating the amplitude or frequency of the RF carrier wave. The data stream of the response signal is composed of a preamble portion (data preamble), a command code, a check bit, and a rolling code for securing the security of the vehicle V in order from the top. The data stream has a fixed length, and the preamble part has a data length of about 100 bits. The transmission bit time (bit rate) of the data stream is transmitted between several Kbps and 20 Kbps.
　車載通信システム２００は、応答信号を受信した場合、無線端末Ｒから受信した複数の応答信号が示す前記要求信号の強度（以下、ＬＦ信号強度と言う）に基づいて、無線端末Ｒの位置を検知する。検知された無線端末Ｒの位置が所定範囲内の位置である場合、車載通信システム２００は、受信した指示受付信号に対応する車両動作の実行を指示する動作指示信号を車両Ｖ内の対応する装置に出力する。これにより、例えば、ドアのロック若しくはアンロック、又は、エンジンの始動が行われる。 When receiving the response signal, the on-vehicle communication system 200 detects the position of the wireless terminal R based on the strengths of the request signals (hereinafter referred to as LF signal strength) indicated by the plurality of response signals received from the wireless terminal R. Do. When the detected position of the wireless terminal R is within the predetermined range, the in-vehicle communication system 200 generates an operation instruction signal for instructing execution of a vehicle operation corresponding to the received instruction reception signal to a corresponding device in the vehicle V Output to Thereby, for example, locking or unlocking of the door or starting of the engine is performed.
　無線端末Ｒは、ドアのロック又はアンロックを指示するドア信号（ＲＦ受信信号）を無線で車載通信システム２００に送信することも可能である。前記ドア信号も、応答信号と同様に、ＲＦ搬送波の振幅又は周波数等を変調することによって生成される信号である。車載通信システム２００は、無線端末Ｒからドア信号を無線で受信した場合、受信したドア信号に応じた動作指示信号を車両Ｖ内の対応する装置に出力する。これにより、ドアのロック又はアンロックが行われる。 The wireless terminal R can also wirelessly transmit a door signal (RF reception signal) instructing lock or unlock of the door to the on-vehicle communication system 200. Like the response signal, the door signal is also a signal generated by modulating the amplitude or frequency of the RF carrier wave. When the on-vehicle communication system 200 wirelessly receives a door signal from the wireless terminal R, the on-vehicle communication system 200 outputs an operation instruction signal corresponding to the received door signal to a corresponding device in the vehicle V. Thereby, the door is locked or unlocked.
　図２は、本実施形態に係る車両Ｖの車載通信システム２００の要部構成を示す機能ブロックである。 FIG. 2 is a functional block diagram showing an essential configuration of the in-vehicle communication system 200 of the vehicle V according to the present embodiment.
　車載通信システム２００は、車載アンテナ装置１００及び制御部１０を備えており、車載アンテナ装置１００はＬＦ送信装置３０及びＲＦ受信装置２０を有している。ＬＦ送信装置３０は、ＬＦ送信回路３１、ツイストペア線Ａ１，Ａ２，Ａ３、及びＬＦ送信アンテナＴ１，Ｔ２，Ｔ３を有する。また、ＲＦ受信装置２０は、ＲＦ受信回路２１、ツイストペア線Ａ１，Ａ２，Ａ３、及びＲＦ受信アンテナＤ１，Ｄ２，Ｄ３を有する。すなわち、ツイストペア線Ａ１，Ａ２，Ａ３はＬＦ送信装置３０及びＲＦ受信装置２０によって共有されている。 The in-vehicle communication system 200 includes an in-vehicle antenna device 100 and a control unit 10. The in-vehicle antenna device 100 includes an LF transmitting device 30 and an RF receiving device 20. The LF transmission device 30 has an LF transmission circuit 31, twisted pair lines A1, A2 and A3, and LF transmission antennas T1, T2 and T3. Further, the RF receiving apparatus 20 includes an RF receiving circuit 21, twisted pair lines A1, A2 and A3, and RF receiving antennas D1, D2 and D3. That is, the twisted pair lines A1, A2 and A3 are shared by the LF transmitter 30 and the RF receiver 20.
　更に、車載通信システム２００は出力部１４、入力部１１、入出力部１２、記憶部１３及び制御部１０を有する。出力部１４、入力部１１、入出力部１２、記憶部１３及び制御部１０はバス１５に接続されている。 Furthermore, the in-vehicle communication system 200 includes an output unit 14, an input unit 11, an input / output unit 12, a storage unit 13, and a control unit 10. The output unit 14, the input unit 11, the input / output unit 12, the storage unit 13, and the control unit 10 are connected to the bus 15.
　ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３夫々には、ツイストペア線Ａ１，Ａ２，Ａ３の一端が夫々接続されている。また、ツイストペア線Ａ１，Ａ２，Ａ３の一端には、更に、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３が接続されている。そしてツイストペア線Ａ１，Ａ２，Ａ３夫々の他端にはＬＦ送信回路３１及びＲＦ受信回路２１が接続されている。すなわち、上述したように、ツイストペア線Ａ１，Ａ２，Ａ３は、ＬＦ送信回路３１及びＲＦ受信回路２１によって共有されている。 One end of each of twisted pair wires A1, A2 and A3 is connected to each of the LF transmitting antennas T1, T2 and T3. Further, RF receiving antennas D1, D2, D3 are further connected to one ends of the twisted pair wires A1, A2, A3. The LF transmission circuit 31 and the RF reception circuit 21 are connected to the other end of each of the twisted pair wires A1, A2 and A3. That is, as described above, the twisted pair lines A1, A2, and A3 are shared by the LF transmission circuit 31 and the RF reception circuit 21.
　ＬＦ送信回路３１は、更に、出力部１４に接続されている。また、ＲＦ受信回路２１は、更に、入力部１１に接続されている。  The LF transmission circuit 31 is further connected to the output unit 14. The RF reception circuit 21 is further connected to the input unit 11.
　出力部１４は、制御部１０の指示に従って、前記要求信号をＬＦ送信回路３１に出力する。ＬＦ送信回路３１は、出力部１４から要求信号が入力された場合、斯かる要求信号を、ツイストペア線Ａ１，Ａ２，Ａ３夫々を介して、ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３に出力する。ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３夫々は、入力された要求信号を無線で無線端末Ｒに出力する。これにより、要求信号が無線端末Ｒに送信される。 The output unit 14 outputs the request signal to the LF transmission circuit 31 in accordance with an instruction from the control unit 10. When a request signal is input from the output unit 14, the LF transmission circuit 31 outputs the request signal to the LF transmission antennas T1, T2 and T3 via the twisted pair lines A1, A2 and A3, respectively. Each of the LF transmission antennas T1, T2 and T3 outputs the input request signal to the radio terminal R by radio. Thereby, a request signal is transmitted to the wireless terminal R.
　ＬＦ送信回路３１は、前記要求信号を、ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３を介して無線端末ＲにＬＦ無線で順次送信する。言い換えると、ＬＦ送信回路３１は、ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３夫々から、時間間隔を空けて前記要求信号を無線端末Ｒに送信する。無線端末Ｒは、１つの要求信号を受信する都度、受信した要求信号のＬＦ信号強度を示す前記応答信号を車載通信システム２００にＲＦ無線で送信する。 The LF transmission circuit 31 sequentially transmits the request signal to the radio terminal R via the LF transmission antennas T1, T2 and T3 by LF radio. In other words, the LF transmission circuit 31 transmits the request signal to the radio terminal R from the LF transmission antennas T1, T2 and T3 with a time interval. Each time the wireless terminal R receives one request signal, it transmits the response signal indicating the LF signal strength of the received request signal to the on-vehicle communication system 200 by RF radio.
　ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３には、無線端末Ｒから応答信号及びドア信号が入力される。ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３に前記応答信号又は前記ドア信号が入力された場合、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３は、入力された応答信号又はドア信号を、ツイストペア線Ａ１，Ａ２，Ａ３を介してＲＦ受信回路２１に出力する。これにより、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３に入力された応答信号又はドア信号は、ＲＦ受信回路２１によって受信される。 A response signal and a door signal are input from the wireless terminal R to the RF receiving antennas D1, D2, and D3. When the response signal or the door signal is input to the RF receiving antenna D1, D2, D3, the RF receiving antenna D1, D2, D3 transmits the input response signal or the door signal to the twisted pair A1, A2, A3. It outputs to the RF receiving circuit 21 via Thus, the response signal or the door signal input to the RF receiving antennas D1, D2, D3 is received by the RF receiving circuit 21.
　ＲＦ受信回路２１は、前記応答信号を受信した場合、受信した応答信号から、前記ＬＦ信号強度を示すＬＦ強度信号を抽出し、抽出したＬＦ強度信号を入力部１１に出力する。前記ＬＦ強度信号は、複数のビット値で構成される。入力部１１は、ＲＦ受信回路２１からＬＦ強度信号が入力された場合、入力されたＬＦ強度信号が示すＬＦ信号強度を制御部１０に通知する。 When the RF receiving circuit 21 receives the response signal, the RF receiving circuit 21 extracts an LF intensity signal indicating the LF signal intensity from the received response signal, and outputs the extracted LF intensity signal to the input unit 11. The LF strength signal is composed of a plurality of bit values. When the LF intensity signal is input from the RF receiving circuit 21, the input unit 11 notifies the control unit 10 of the LF signal intensity indicated by the input LF intensity signal.
　ＲＦ受信回路２１は、前記ドア信号を受信した場合、受信したドア信号から、斯かるドア信号の指示内容を示す内容信号を抽出し、抽出した内容信号を入力部１１に出力する。内容信号も複数のビット値で構成される。入力部１１は、ＲＦ受信回路２１から前記内容信号が入力された場合、入力された内容信号が示す指示内容を制御部１０に通知する。 When the RF reception circuit 21 receives the door signal, the RF reception circuit 21 extracts a content signal indicating an instruction content of the door signal from the received door signal, and outputs the extracted content signal to the input unit 11. The content signal is also composed of a plurality of bit values. When the content signal is input from the RF reception circuit 21, the input unit 11 notifies the control unit 10 of the instruction content indicated by the input content signal.
　入出力部１２には、車両Ｖ内の各装置から前記指示受付信号が入力される。入出力部１２は、前記指示受付信号が入力された場合、入力された指示受付信号が示す内容を制御部１０に通知する。また、入出力部１２は、制御部１０の指示に従って、前記車両動作の実行を指示する前記動作指示信号を車両Ｖ内の対応する装置に出力する。 The instruction acceptance signal is input to the input / output unit 12 from each device in the vehicle V. When the instruction acceptance signal is input, the input / output unit 12 notifies the control unit 10 of the content indicated by the input instruction acceptance signal. Further, the input / output unit 12 outputs the operation instruction signal instructing execution of the vehicle operation to a corresponding device in the vehicle V according to an instruction of the control unit 10.
　記憶部１３は不揮発性メモリである。記憶部１３には、コンピュータプログラムＰが記憶されている。制御部１０は、図示しないＣＰＵ(Central Processing Unit)を有する。制御部１０のＣＰＵは、コンピュータプログラムＰを実行することによって種々の処理を実行する。 The storage unit 13 is a non-volatile memory. The storage unit 13 stores a computer program P. The control unit 10 has a CPU (Central Processing Unit) not shown. The CPU of the control unit 10 executes various processes by executing the computer program P.
　制御部１０は、入出力部１２に前記指示受付信号が入力された場合、出力部１４に指示して、前記要求信号をＬＦ送信回路３１に出力させる。これにより、ＬＦ送信回路３１は、ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３を介して、時間間隔を空けて３つの要求信号を無線端末Ｒに順次ＬＦ送信する。この際、前述したように、無線端末Ｒは、前記要求信号を受信する都度、前記応答信号を車載通信システム２００にＲＦ送信する。ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３に前記応答信号が入力されてＲＦ受信回路２１が前記応答信号を受信した場合、ＲＦ受信回路２１は受信された応答信号に係るＬＦ強度信号を入力部１１に出力する。 When the instruction acceptance signal is input to the input / output unit 12, the control unit 10 instructs the output unit 14 to output the request signal to the LF transmission circuit 31. As a result, the LF transmission circuit 31 sequentially LF-transmits three request signals to the radio terminal R at time intervals via the LF transmission antennas T1, T2 and T3. At this time, as described above, each time the wireless terminal R receives the request signal, it transmits the response signal to the on-vehicle communication system 200 by RF. When the response signal is input to the RF receiving antennas D1, D2 and D3 and the RF receiving circuit 21 receives the response signal, the RF receiving circuit 21 outputs the LF intensity signal according to the received response signal to the input unit 11. Do.
　制御部１０は、入力部１１に複数のＬＦ強度信号が入力された場合、これらのＬＦ強度信号が示す複数の強度に基づいて、無線端末Ｒの位置を検知する。制御部１０は、検知した無線端末Ｒの位置が所定範囲内である場合、入出力部１２に指示し、前記指示受付信号に対応する車両Ｖ内の所定装置に前記動作指示信号を出力させる。これにより、例えば、ドアのロック若しくはアンロック、又は、エンジンの始動が行われる。 When a plurality of LF strength signals are input to the input unit 11, the control unit 10 detects the position of the wireless terminal R based on the plurality of strengths indicated by the LF strength signals. When the detected position of the wireless terminal R is within the predetermined range, the control unit 10 instructs the input / output unit 12 to output the operation instruction signal to a predetermined device in the vehicle V corresponding to the instruction reception signal. Thereby, for example, locking or unlocking of the door or starting of the engine is performed.
　制御部１０は、例えば、ＲＦ受信回路２１がＲＦ受信アンテナＤ１，Ｄ２，Ｄ３を介して前記ドア信号を受信して入力部１１に内容信号が入力された場合、入出力部１２に指示して、車両Ｖ内における、前記ドア信号に対応する装置に動作指示信号を出力させる。これにより、ドアのロック又はアンロックが行われる。 For example, when the RF receiving circuit 21 receives the door signal via the RF receiving antennas D1, D2 and D3 and the content signal is input to the input unit 11, the control unit 10 instructs the input / output unit 12 And an operation instruction signal is output to a device corresponding to the door signal in the vehicle V. Thereby, the door is locked or unlocked.
　要求信号の周波数帯域は、応答信号及びドア信号の周波数帯域と異なる。要求信号の周波数帯域は低く、応答信号及びドア信号の周波数帯域は高い。要求信号の周波数帯域は、例えば、１００ｋＨｚから２００ｋＨｚの範囲内に含まれるＬＦ帯である。応答信号及びドア信号夫々の周波数帯域は、例えば、３００ＭＨｚから４００ＭＨｚの範囲内に含まれるＲＦ(ＵＨＦ)帯である。 The frequency band of the request signal is different from the frequency band of the response signal and the door signal. The frequency band of the request signal is low, and the frequency band of the response signal and the door signal is high. The frequency band of the request signal is, for example, an LF band included in the range of 100 kHz to 200 kHz. The frequency band of each of the response signal and the door signal is, for example, an RF (UHF) band included in the range of 300 MHz to 400 MHz.
　ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３夫々は、車両Ｖの進行方向に対して、車両Ｖの右側ドア付近、左側ドア付近、及びリアラゲッジ内に配置されている。上述したように、ＬＦ送信装置３０及びＲＦ受信装置２０がツイストペア線Ａ１，Ａ２，Ａ３を共有している。そのため、ＬＦ送信アンテナＴ１，Ｔ２，Ｔ３と、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３とは互いに近傍に設けられている。
　これによって、本実施形態の車載アンテナ装置１００は、部品点数を減らすことができると共に、その構成をより簡単にすることができる。 The LF transmitting antennas T1, T2 and T3 are respectively disposed in the vicinity of the right door, in the vicinity of the left door, and in the rear luggage in the traveling direction of the vehicle V. As described above, the LF transmitter 30 and the RF receiver 20 share the twisted pair lines A1, A2, and A3. Therefore, the LF transmission antennas T1, T2 and T3 and the RF reception antennas D1, D2 and D3 are provided in the vicinity of each other.
As a result, in the on-vehicle antenna device 100 according to the present embodiment, the number of parts can be reduced, and the configuration can be simplified.
　図３は、本実施形態の車載アンテナ装置１００における、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３の配置を説明する例示図である。ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３は、夫々車両Ｖの右側窓、左側窓、裏側窓に設けられている。以下においては、説明の便宜上、ＲＦ受信アンテナＤ１を例に挙げて説明する。 FIG. 3 is an exemplary view for explaining the arrangement of the RF receiving antennas D1, D2, and D3 in the on-vehicle antenna device 100 of the present embodiment. The RF receiving antennas D1, D2, and D3 are respectively provided on the right side window, the left side window, and the rear side window of the vehicle V. In the following, for convenience of explanation, the RF receiving antenna D1 will be described as an example.
　ＲＦ受信アンテナＤ１は、車両Ｖの右側窓Ｗに付着されており、車両Ｖの右側ドアＲＤには、上述したように、ＬＦ送信アンテナＴ１が設けられている（図示せず）。
　ＲＦ受信アンテナＤ１は、前記応答信号及び前記ドア信号に対応できるＵＨＦ帯のダイポールアンテナである。ＲＦ受信アンテナＤ１は、前記応答信号及び前記ドア信号を受信するアンテナエレメント２５ａ，２５ｂ（ＲＦ受信アンテナ素子）がＬ字状をなす。アンテナエレメント２５ａ，２５ｂはフイルム状の透視可能材料からなる。透視可能とは、透明な状態を含み、所定の可視光線透過率（例えば、８０％以上）を有すれば良い。 The RF receiving antenna D1 is attached to the right window W of the vehicle V, and the LF transmitting antenna T1 is provided on the right door RD of the vehicle V as described above (not shown).
The RF receiving antenna D1 is a UHF band dipole antenna that can correspond to the response signal and the door signal. In the RF receiving antenna D1, antenna elements 25a and 25b (RF receiving antenna elements) for receiving the response signal and the door signal form an L shape. The antenna elements 25a, 25b are made of a film-like see-through material. The term "visible" includes a transparent state, and may have a predetermined visible light transmittance (for example, 80% or more).
　前記透視可能材料としては、例えば、アンテナエレメント２５ａ，２５ｂは、ＦＴＯ（フッ素ドープ酸化スズ）、ＩＴＯ（スズドープ酸化インジウム），ＡＺＯ（ＺｎＯ：Ａｌ），ＧＺＯ（ＺｎＯ：Ｇａ）等からなる。
　その他、ＲＦ受信アンテナＤ２，Ｄ３については、ＲＦ受信アンテナＤ１と同様であり、詳しい説明を省略する。 As the see-through material, for example, the antenna elements 25a and 25b are made of FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), AZO (ZnO: Al), GZO (ZnO: Ga) or the like.
The other RF receiving antennas D2 and D3 are the same as the RF receiving antenna D1, and the detailed description will be omitted.
　上述したように、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３は、夫々車両Ｖの右側窓、左側窓、裏側窓に夫々設けられている。右側窓は車両Ｖの右側に面しており、左側窓は車両Ｖの左側に面しており、裏側は車両Ｖの後側に面している。従って、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３は、向かう方向が異なる窓に夫々設けられている。 As described above, the RF receiving antennas D1, D2, and D3 are respectively provided on the right side window, the left side window, and the rear side window of the vehicle V. The right side window faces the right side of the vehicle V, the left side window faces the left side of the vehicle V, and the rear side faces the rear side of the vehicle V. Therefore, the RF receiving antennas D1, D2 and D3 are respectively provided in windows having different directions.
　車両Ｖのデザイン性を考慮し、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３が車両Ｖの隠れた場所に設けられた場合は、車台などに遮蔽され、設置位置によっては前記応答信号及び前記ドア信号等の受信が出来ない場合がある。これに対して、本実施形態の車載アンテナ装置１００においては、このように、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３が車両Ｖの窓に設けられているから、車両デザイン性及び運転者の視認性を害せず、前記応答信号及び前記ドア信号等の受信が妨げられることもなく、受信率を高めることができる。 If the RF receiving antennas D1, D2 and D3 are provided in a hidden place of the vehicle V in consideration of the design of the vehicle V, they are shielded by the chassis etc., and the response signal and the door signal etc. There is a case that can not be received. On the other hand, in the on-vehicle antenna device 100 according to the present embodiment, since the RF receiving antennas D1, D2, and D3 are thus provided in the window of the vehicle V, the vehicle design and the driver's visibility are improved. It is possible to increase the reception rate without harming the reception of the response signal and the door signal and the like.
　また、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３は水平偏波指向性を有する。水平偏波指向性とは、受信感度を表す信号強度（電界強度）が水平に分布し、アンテナの指向性すなわち感知領域が水平となる特性である。ＲＦ受信アンテナＤ１，Ｄ２（一のＲＦ受信アンテナ）と、ＲＦ受信アンテナＤ３（他のＲＦ受信アンテナ）とは、その水平偏波指向性が相違する。詳しくは、ＲＦ受信アンテナＤ１，Ｄ２及びＲＦ受信アンテナＤ３は互いに水平偏波指向性によるディップ（以下、単にディップと略す）の方向が異なる。 Also, the RF receiving antennas D1, D2, D3 have horizontal polarization directivity. The horizontal polarization directivity is a characteristic in which the signal strength (field strength) representing the reception sensitivity is distributed horizontally, and the directivity of the antenna, that is, the sensing area becomes horizontal. The horizontal polarization directivity of the RF receiving antennas D1 and D2 (one RF receiving antenna) and the RF receiving antenna D3 (another RF receiving antenna) are different. Specifically, the directions of dips (hereinafter simply referred to as dips) due to horizontal polarization directivity differ from each other between the RF receiving antennas D1 and D2 and the RF receiving antenna D3.
　図４は、本実施形態の車載アンテナ装置１００におけるＲＦ受信アンテナＤ１，Ｄ２，Ｄ３の水平偏波指向性の利得を示すグラフである。図４Ａは車両Ｖの後側窓のＲＦ受信アンテナＤ３の水平偏波指向性を示しており、図４Ｂは車両Ｖの右側窓及び左側窓のＲＦ受信アンテナＤ１，Ｄ２の水平偏波指向性を示している。 FIG. 4 is a graph showing the gain of the horizontal polarization directivity of the RF receiving antennas D1, D2, and D3 in the on-vehicle antenna device 100 of the present embodiment. FIG. 4A shows the horizontal polarization directivity of the RF reception antenna D3 of the rear window of the vehicle V, and FIG. 4B shows the horizontal polarization directivity of the RF reception antennas D1 and D2 of the right and left windows of the vehicle V It shows.
　ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３の感知領域Ｓ１には、何れも、水平方向において信号強度が著しく低下するディップＳ２が存在する。斯かるディップＳ２の存在により、通信距離等が変化したときに、通信電波の信号レベルが急激に落ち込み、通信が不可能になる虞がある。 In any of the sensing areas S1 of the RF receiving antennas D1, D2, and D3, there is a dip S2 in which the signal strength significantly decreases in the horizontal direction. Due to the presence of such a dip S2, when the communication distance or the like changes, the signal level of the communication radio wave may drop sharply, and communication may become impossible.
　図４Ａ，Ｂにおいて、夫々の感知領域Ｓ１には、ディップＳ２による不感領域が存在する。図４ＡのＲＦ受信アンテナＤ３（後側窓）のディップＳ２の方向に対し、図４ＢのＲＦ受信アンテナＤ１，Ｄ２（右側窓・左側窓）のディップＳ２の方向は、異ならせている。ディップＳ２の方向とは、円の中心に位置するＲＦ受信アンテナからの方向である。本実施形態では、紙面視、円状の分布図の中心Ｓ３より上方向を０°とした場合、ＲＦ受信アンテナＤ３のディップＳ２の方向は９０°，２７０°である。一方、ＲＦ受信アンテナＤ１，Ｄ２のディップＳ２の方向は０°，１８０°である。ＲＦ受信アンテナＤ３とＲＦ受信アンテナＤ１，Ｄ２とのディップＳ２の方向が、すなわち、夫々のディップＳ２による不感領域が重ならないように構成されてある。 In FIGS. 4A and 4B, in each sensing area S1, there is a dead area due to the dip S2. The directions of dips S2 of the RF receiving antennas D1 and D2 (right and left windows) of FIG. 4B are different from the directions of the dips S2 of the RF receiving antenna D3 (rear side window) of FIG. 4A. The direction of dip S2 is the direction from the RF receiving antenna located at the center of the circle. In the present embodiment, the direction of the dip S2 of the RF receiving antenna D3 is 90.degree. On the other hand, the directions of dips S2 of the RF receiving antennas D1 and D2 are 0 ° and 180 °. The directions of the dips S2 of the RF receiving antenna D3 and the RF receiving antennas D1 and D2 are configured such that the insensitive regions due to the respective dips S2 do not overlap.
　このように、ＲＦ受信アンテナＤ３とＲＦ受信アンテナＤ１，Ｄ２とがディップＳ２の方向を異にしているので、ＲＦ受信アンテナＤ３とＲＦ受信アンテナＤ１，Ｄ２とにおける不感領域を互いにて補うことができる。すなわち、ディップＳ２による影響を受けていない何れかのＲＦ受信アンテナを適宜選択することによって、ディップＳ２による障害を防ぎ、通信可能領域及び安定した通信状態を確保することができる。 As described above, since the directions of the dips S2 are different between the RF receiving antenna D3 and the RF receiving antennas D1 and D2, the dead zones in the RF receiving antenna D3 and the RF receiving antennas D1 and D2 can be mutually compensated. . That is, by selecting any RF receiving antenna not affected by the dip S2, a failure due to the dip S2 can be prevented, and a communicable area and a stable communication state can be secured.
　以上においては、ＲＦ受信アンテナＤ１，Ｄ２が同じ水平偏波指向性（ディップＳ２）を有する場合を例に挙げて説明したが、本実施形態はこれに限りものでない。例えば、ＲＦ受信アンテナＤ１、ＲＦ受信アンテナＤ２及びＲＦ受信アンテナＤ３のディップの方向が夫々異なるようにしても良い。 Although the case where RF receiving antennas D1 and D2 have the same horizontal polarization directivity (dip S2) has been described above as an example, the present embodiment is not limited to this. For example, the dip directions of the RF receiving antenna D1, the RF receiving antenna D2, and the RF receiving antenna D3 may be different from each other.
　図５及び図６は、本実施形態の車載アンテナ装置１００の構成を示す概略的回路図である。図５は、車載アンテナ装置１００において、ツイストペア線Ａ１，Ａ２，Ａ３に対して、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３及びＬＦ送信アンテナＴ１，Ｔ２，Ｔ３側を示している。図６は、ツイストペア線Ａ１，Ａ２，Ａ３に対して、ＬＦ送信回路３１及びＲＦ受信回路２１側を示している。説明の便宜上、以下においては、ＲＦ受信アンテナＤ１及びＬＦ送信アンテナＴ１の場合を例に挙げて説明し、ＲＦ受信アンテナＤ２及びＬＦ送信アンテナＴ２と、ＲＦ受信アンテナＤ３及びＬＦ送信アンテナＴ３については、詳しい説明を省略する。 FIG.5 and FIG.6 is a schematic circuit diagram which shows the structure of the vehicle-mounted antenna apparatus 100 of this embodiment. FIG. 5 shows the side of the RF reception antennas D1, D2, D3 and the LF transmission antennas T1, T2, T3 with respect to the twisted pair lines A1, A2, A3 in the on-vehicle antenna device 100. FIG. 6 shows the side of the LF transmission circuit 31 and the RF reception circuit 21 with respect to the twisted pair lines A1, A2 and A3. For convenience of explanation, in the following, the case of the RF receiving antenna D1 and the LF transmitting antenna T1 will be described as an example, and the RF receiving antenna D2 and the LF transmitting antenna T2, and the RF receiving antenna D3 and the LF transmitting antenna T3 will be described. Detailed explanation is omitted.
　ＲＦ受信アンテナＤ１のアンテナエレメント２５ａ，２５ｂ夫々は、図３に示すように、互いに対称的に配置されているダイポールアンテナ形状をなす。アンテナエレメント２５ａにおいての一端部にキャパシタＣ１の一端が接続されている。同様に、アンテナエレメント２５ｂにおいての一端部にキャパシタＣ２の一端が接続されている。キャパシタＣ１，Ｃ２のインピーダンスは、例えば、１００ｐＦである。 Each of the antenna elements 25a and 25b of the RF receiving antenna D1 has a dipole antenna shape which is disposed symmetrically to each other as shown in FIG. One end of the capacitor C1 is connected to one end of the antenna element 25a. Similarly, one end of the capacitor C2 is connected to one end of the antenna element 25b. The impedance of the capacitors C1 and C2 is, for example, 100 pF.
　ツイストペア線Ａ１は、撚り合されている２つの導線２６ａ，２６ｂを有する。ＲＦ受信アンテナＤ１が有するキャパシタＣ１，Ｃ２夫々の他端は、導線２６ａ，２６ｂの一端に接続されている。導線２６ａ，２６ｂの他端はＬＦ送信回路３１及びＲＦ受信回路２１に接続されている。ツイストペア線Ａ１の一端付近には、導線２６ａ，２６ｂの一端が配置され、ツイストペア線Ａ１の他端付近には、導線２６ａ，２６ｂの他端が配置されている。 The twisted pair wire A1 has two conducting wires 26a and 26b which are twisted together. The other end of each of the capacitors C1 and C2 of the RF receiving antenna D1 is connected to one end of the conducting wire 26a and 26b. The other ends of the conductors 26 a and 26 b are connected to the LF transmitter circuit 31 and the RF receiver circuit 21. One end of the conducting wire 26a, 26b is disposed near one end of the twisted pair wire A1, and the other end of the conducting wire 26a, 26b is disposed near the other end of the twisted pair wire A1.
　上述したように、ＲＦ受信アンテナＤ１は、ダイポールアンテナであるので、入力された応答信号（又はドア信号）を、２つのキャパシタＣ１，Ｃ２の他端から、ツイストペア線Ａ１の２つの導線２６ａ，２６ｂを介してＲＦ受信回路２１に出力する。ツイストペア線Ａ１を介して出力される応答信号及びドア信号夫々は、平衡な信号、すなわち、２つの導線２６ａ，２６ｂの電圧差で示される信号である。 As described above, since the RF receiving antenna D1 is a dipole antenna, the input response signal (or door signal) is transmitted from the other end of the two capacitors C1 and C2 to the two conductors 26a and 26b of the twisted pair A1. To the RF receiving circuit 21 via Each of the response signal and the door signal output through the twisted pair A1 is a balanced signal, that is, a signal indicated by a voltage difference between the two conductors 26a and 26b.
　一方、ＬＦ送信アンテナＴ１は、コイル２７を有するいわゆるバーコイルアンテナである。コイル２７のインダクタンスは、例えば、３５０～７８０μＨである。コイル２７の一端は導線２６ａの一端側に接続されている。コイル２７の他端は導線２６ｂの一端側に接続されている。キャパシタＣ１の他端はコイル２７と導線２６ａとの接点に接続され、キャパシタＣ２の他端はコイル２７の他端と導線２６ｂとの接点に接続される。ＬＦ送信アンテナＴ１はツイストペア線Ａ１を介して、ＬＦ送信回路３１から出力された前記要求信号を無線端末Ｒに出力する。 On the other hand, the LF transmission antenna T1 is a so-called bar coil antenna having a coil 27. The inductance of the coil 27 is, for example, 350 to 780 μH. One end of the coil 27 is connected to one end of the conducting wire 26a. The other end of the coil 27 is connected to one end of the conducting wire 26b. The other end of the capacitor C1 is connected to the contact between the coil 27 and the lead 26a, and the other end of the capacitor C2 is connected to the contact between the other end of the coil 27 and the lead 26b. The LF transmission antenna T1 outputs the request signal output from the LF transmission circuit 31 to the radio terminal R via the twisted pair wire A1.
　キャパシタＣ１，Ｃ２夫々のインピーダンスの絶対値は、周波数帯域が低い前記要求信号に対して大きく、周波数帯域が高い前記応答信号及び前記ドア信号に対して小さい。すなわち、キャパシタＣ１，Ｃ２は、ＬＦ送信回路３１がツイストペア線Ａ１を介して出力した要求信号がＲＦ受信アンテナＤ１から外部に出力されることを防止する。 The absolute value of the impedance of each of the capacitors C1 and C2 is large for the request signal having a low frequency band and small for the response signal and the door signal having a high frequency band. That is, the capacitors C1 and C2 prevent the request signal output from the LF transmission circuit 31 through the twisted pair line A1 from being output from the RF receiving antenna D1 to the outside.
　また、コイル２７のインピーダンスの絶対値は、周波数帯域が低い前記要求信号に対して小さく、周波数帯域が高い前記応答信号及び前記ドア信号に対して大きい。すなわち、コイル２７は、ＲＦ受信アンテナＤ１が受信した応答信号及びドア信号がＬＦ送信アンテナＴ１から外部に出力されることを防止する。 Further, the absolute value of the impedance of the coil 27 is smaller for the request signal having a lower frequency band and larger for the response signal and the door signal having a higher frequency band. That is, the coil 27 prevents the response signal and the door signal received by the RF receiving antenna D1 from being output from the LF transmitting antenna T1 to the outside.
　図７は本実施形態の車載アンテナ装置１００において、キャパシタＣ１，Ｃ２による効果をシミュレーションした結果を表すグラフである。図７に示すように、キャパシタＣ１，Ｃ２を設けることによって、前記応答信号及び前記ドア信号に対しては、コイル２７による漏洩に起因する損失を０．０１１ｄＢ程度以下にすることができる。また、前記要求信号に対しては、ＲＦ受信アンテナＤ１による漏洩に起因する損失を‐４４．４ｄＢ程度以下にすることができる。 FIG. 7 is a graph showing the simulation result of the effects of the capacitors C1 and C2 in the on-vehicle antenna device 100 of the present embodiment. As shown in FIG. 7, by providing the capacitors C1 and C2, the loss due to the leakage by the coil 27 can be reduced to about 0.011 dB or less for the response signal and the door signal. Further, for the request signal, the loss due to the leakage by the RF receiving antenna D1 can be made about -44.4 dB or less.
　ＬＦ送信回路３１は、駆動部３２及びインダクタ３３ａ，３３ｂを有する。駆動部３２は、前記要求信号を出力する。インダクタ３３ａの一端は、ツイストペア線Ａ１の導線２６ａの他端側に接続されている。インダクタ３３ｂの一端は、ツイストペア線Ａ１の導線２６ｂの他端側に接続されている。インダクタ３３ａ，３３ｂの他端は、駆動部３２に接続されている。インダクタ３３ａ，３３ｂのインダクタンスは、例えば、１μＨである。 The LF transmission circuit 31 includes a drive unit 32 and inductors 33a and 33b. The drive unit 32 outputs the request signal. One end of the inductor 33a is connected to the other end side of the conducting wire 26a of the twisted pair wire A1. One end of the inductor 33b is connected to the other end side of the conductor 26b of the twisted pair wire A1. The other ends of the inductors 33 a and 33 b are connected to the drive unit 32. The inductance of the inductors 33a and 33b is, for example, 1 μH.
　インダクタ３３ａ，３３ｂのインピーダンスの絶対値は、周波数帯域が高い前記応答信号及び前記ドア信号に対して大きい。従って、インダクタ３３ａ，３３ｂは、ＲＦ受信アンテナＤ１が受信した応答信号及びドア信号が駆動部３２に入力されることを防止する。 The absolute value of the impedance of the inductors 33a and 33b is larger than the response signal and the door signal whose frequency band is high. Therefore, the inductors 33a and 33b prevent the response signal and the door signal received by the RF receiving antenna D1 from being input to the driving unit 32.
　ＲＦ受信回路２１は、変換回路２８及びキャパシタＣ３，Ｃ４を有する。キャパシタＣ３の一端は、ツイストペア線Ａ１の導線２６ａの他端側に接続されている。キャパシタＣ４の一端は、ツイストペア線Ａ１の導線２６ｂの他端側に接続されている。キャパシタＣ３，Ｃ４の他端は、変換回路２８に接続されている。変換回路２８は、更に、後述する切替部２２を介して後述する抽出部２３に接続されている。抽出部２３は、更に、入力部１１に接続されている。変換回路２８は接地されている。 The RF reception circuit 21 has a conversion circuit 28 and capacitors C3 and C4. One end of the capacitor C3 is connected to the other end side of the conducting wire 26a of the twisted pair wire A1. One end of the capacitor C4 is connected to the other end side of the conducting wire 26b of the twisted pair wire A1. The other ends of the capacitors C3 and C4 are connected to the conversion circuit 28. The conversion circuit 28 is further connected to an extraction unit 23 described later via a switching unit 22 described later. The extraction unit 23 is further connected to the input unit 11. The conversion circuit 28 is grounded.
　変換回路２８は、平衡な応答信号が入力された場合、入力された平衡な応答信号を、接地電位を基準とした不平衡な応答信号に変換し、変換した応答信号を抽出部２３に出力する。不平衡な信号は、固定電位、例えば接地電位を基準とした信号である。
　ＲＦ受信アンテナＤ１からツイストペア線Ａ１を介して変換回路２８平衡な応答信号及びドア信号が入力され、変換回路２８は、入力された平衡な応答信号及びドア信号を、不平衡な応答信号及びドア信号に変換して抽出部２３に出力する。 When the balanced response signal is input, the conversion circuit 28 converts the input balanced response signal into an unbalanced response signal based on the ground potential, and outputs the converted response signal to the extraction unit 23. . An unbalanced signal is a signal referenced to a fixed potential, eg, ground potential.
The balanced response signal and the door signal are input from the RF receiving antenna D1 via the twisted pair wire A1, and the translating circuit 28 receives the unbalanced response signal and the door signal as an unbalanced response signal and the door signal. And output to the extraction unit 23.
　キャパシタＣ３，Ｃ４のインダクタンスの絶対値は、周波数帯域が低い前記要求信号に対して大きく、周波数帯域が高い前記応答信号及び前記ドア信号に対して小さい。従ってキャパシタＣ３，Ｃ４は、ＬＦ送信回路３１がＬＦ送信アンテナＴ１に出力した要求信号が変換回路２８に入力されることを防ぐ。 The absolute values of the inductances of the capacitors C3 and C4 are large for the request signal having a low frequency band and small for the response signal and the door signal having a high frequency band. Therefore, the capacitors C3 and C4 prevent the request signal output from the LF transmission circuit 31 to the LF transmission antenna T1 from being input to the conversion circuit 28.
　図８は本実施形態の車載アンテナ装置１００において、インダクタ３３ａ，３３ｂ及びキャパシタＣ３，Ｃ４による効果をシミュレーションした結果を表すグラフである。図８に示すように、インダクタ３３ａ，３３ｂを設けることによって、前記応答信号及び前記ドア信号に対して、駆動部３２による漏洩に起因する損失を０．０１ｄＢにすることができる。また、キャパシタＣ３，Ｃ４を設けることによって、前記要求信号に対して、変換回路２８による漏洩に起因する損失を‐４９．６ｄＢ程度以下にすることができる。 FIG. 8 is a graph showing the simulation result of the effects of the inductors 33a and 33b and the capacitors C3 and C4 in the on-vehicle antenna device 100 of the present embodiment. As shown in FIG. 8, by providing the inductors 33a and 33b, the loss due to the leakage by the drive unit 32 can be made 0.01 dB for the response signal and the door signal. Further, by providing the capacitors C3 and C4, the loss due to the leakage by the conversion circuit 28 can be made about -49.6 dB or less with respect to the request signal.
　図９は、本実施形態の車載アンテナ装置１００における、ＲＦ受信回路２１の構成を示す機能ブロック図である。図９においては、説明の便宜上、キャパシタＣ３，Ｃ４の表示を省略している。 FIG. 9 is a functional block diagram showing the configuration of the RF receiving circuit 21 in the on-vehicle antenna device 100 of the present embodiment. In FIG. 9, for convenience of description, the display of the capacitors C3 and C4 is omitted.
　ＲＦ受信回路２１は、変換回路２８及びキャパシタＣ３，Ｃ４に加え、切替部２２（選択部）及び抽出部２３を有している。ＲＦ受信回路２１は例えば、３つの変換回路２８を有しており、変換回路２８毎に、上述したように、キャパシタＣ３，Ｃ４が設けられている。 The RF reception circuit 21 includes a switching unit 22 (selection unit) and an extraction unit 23 in addition to the conversion circuit 28 and the capacitors C3 and C4. The RF receiving circuit 21 has, for example, three conversion circuits 28. As described above, the capacitors C3 and C4 are provided for each of the conversion circuits 28.
　３つの変換回路２８によって、不平衡な信号に変換された応答信号又はドア信号は切替部２２に送られ、何れかの応答信号及びドア信号が抽出部２３に送られる。
　切替部２２は、３つの変換回路２８と抽出部２３との間に介在している。各変換回路２８は一本の導線２４ａ，２４ｂ，２４ｃによって接続されており、斯かる導線２４ａ，２４ｂ，２４ｃを介して、不平衡な応答信号又はドア信号が切替部２２に入力される。 The response signal or the door signal converted into the unbalanced signal by the three conversion circuits 28 is sent to the switching unit 22, and any response signal and the door signal are sent to the extraction unit 23.
The switching unit 22 is interposed between the three conversion circuits 28 and the extraction unit 23. Each conversion circuit 28 is connected by a single lead 24 a, 24 b, 24 c, and an unbalanced response signal or door signal is input to the switching unit 22 through the leads 24 a, 24 b, 24 c.
　切替部２２は、所定周期にて、導線２４ａ，２４ｂ，２４ｃのうち、何れかの導線に接続を切り替える。これによって、切替部２２はＲＦ受信アンテナＤ１，Ｄ２，Ｄ３のうち、何れかのＲＦ受信アンテナを選択できる。前記所定周期は、無線端末Ｒから送信させる応答信号の送信ビット時間に応じて設定される。例えば、切替えの所定周期をプリアンブル部における５ｂｉｔ分を取得する時間で設定した場合、ビット時間が２ｋｂｐｓであれば、切替部２２は、２．５ミリ秒間隔で、前記切替えを行う。 The switching unit 22 switches the connection to any one of the conductors 24a, 24b, and 24c at a predetermined cycle. As a result, the switching unit 22 can select any one of the RF receiving antennas D1, D2, and D3. The predetermined cycle is set according to the transmission bit time of the response signal to be transmitted from the wireless terminal R. For example, when the predetermined period of switching is set by the time for acquiring 5 bits in the preamble unit, if the bit time is 2 kbps, the switching unit 22 performs the switching at an interval of 2.5 milliseconds.
　制御部１０は、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３の夫々を介して受信された応答信号に係る信号強度（以下、ＲＦ信号強度と言う）を比較する。そして、最も強いＲＦ信号強度を選択し、選択されたＲＦ信号強度に対応するＲＦ受信アンテナを選択するための切替制御信号を切替部２２に出力する。制御部１０からの切替制御信号が入力されると、切替部２２は、所定周期での切替えを中止し、前記切替制御信号に基づいて、導線２４ａ，２４ｂ，２４ｃの何れかに接続の切替えを行う。 The control unit 10 compares signal strengths (hereinafter referred to as RF signal strengths) related to response signals received through the RF receiving antennas D1, D2, and D3. Then, a switching control signal for selecting the strongest RF signal strength and selecting an RF receiving antenna corresponding to the selected RF signal strength is output to the switching unit 22. When the switching control signal from the control unit 10 is input, the switching unit 22 stops switching at a predetermined cycle, and switching of connection to any one of the conductors 24a, 24b, 24c is performed based on the switching control signal. Do.
　抽出部２３は、切替部２２によって接続された導線からの不平衡な応答信号又はドア信号から前記ＲＦ信号強度を示すＲＦ強度信号を抽出し、抽出したＲＦ強度信号を入力部１１に出力する。 The extraction unit 23 extracts an RF intensity signal indicating the RF signal intensity from the unbalanced response signal or door signal from the lead wire connected by the switching unit 22, and outputs the extracted RF intensity signal to the input unit 11.
　図１０は、本実施形態に係る車載アンテナ装置１００における応答信号の受信処理を説明するフローチャートである。制御部１０は、以下に示す処理手順を常時的に実行する。 FIG. 10 is a flowchart for explaining the reception process of the response signal in the on-vehicle antenna device 100 according to the present embodiment. The control unit 10 constantly executes the processing procedure described below.
　制御部１０は、ＲＦ受信アンテナＤ１，Ｄ２，Ｄ３の何れかに受信される応答信号を所定期間、待ち受ける。何れかのＲＦ受信アンテナ（例えば、ＲＦ受信アンテナＤ１）が応答信号を受信した場合、制御部１０は、ＲＦ受信回路２１を介して、受信された応答信号のＲＦ信号強度を取得する（ステップＳ１０１）。制御部１０は、取得したＲＦ信号強度及びＲＦ受信アンテナＤ１の特定情報を対応付けて記憶部１３に記憶する。 The control unit 10 waits for a response signal received by any of the RF receiving antennas D1, D2, and D3 for a predetermined period. When one of the RF receiving antennas (for example, the RF receiving antenna D1) receives the response signal, the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S101). ). The control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D1 in the storage unit 13 in association with each other.
　次いで、制御部１０は、ＲＦ受信アンテナＤ２、すなわち導線２４ｂへ接続を切り替える旨の切替制御信号を切替部２２に出力する。切替部２２は、前記切替制御信号に基づき、導線２４ａから導線２４ｂへ接続の切替えを行う。 Next, the control unit 10 outputs, to the switching unit 22, a switching control signal indicating that the connection is switched to the RF receiving antenna D2, that is, the lead 24b. The switching unit 22 switches the connection from the conducting wire 24 a to the conducting wire 24 b based on the switching control signal.
　制御部１０は、ＲＦ受信アンテナＤ２に受信される応答信号を所定期間、待ち受ける。ＲＦ受信アンテナＤ２が応答信号を受信した場合、制御部１０は、ＲＦ受信回路２１を介して、受信された応答信号のＲＦ信号強度を取得する（ステップＳ１０２）。制御部１０は、取得したＲＦ信号強度及びＲＦ受信アンテナＤ２の特定情報を対応付けて記憶部１３に記憶する。 The control unit 10 waits for a response signal received by the RF receiving antenna D2 for a predetermined period. When the RF receiving antenna D2 receives the response signal, the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S102). The control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D2 in the storage unit 13 in association with each other.
　次いで、制御部１０は、ＲＦ受信アンテナＤ３、すなわち導線２４ｃへ接続を切り替える旨の切替制御信号を切替部２２に出力する。切替部２２は、前記切替制御信号に基づき、導線２４ｂから導線２４ｃへ接続の切替えを行う。 Next, the control unit 10 outputs, to the switching unit 22, a switching control signal indicating that the connection is switched to the RF receiving antenna D3, that is, the lead 24c. The switching unit 22 switches the connection from the lead 24b to the lead 24c based on the switching control signal.
　制御部１０は、ＲＦ受信アンテナＤ３に受信される応答信号を所定期間、待ち受ける。ＲＦ受信アンテナＤ３が応答信号を受信した場合、制御部１０は、ＲＦ受信回路２１を介して、受信された応答信号のＲＦ信号強度を取得する（ステップＳ１０３）。制御部１０は、取得したＲＦ信号強度及びＲＦ受信アンテナＤ３の特定情報を対応付けて記憶部１３に記憶する。 The control unit 10 waits for a response signal received by the RF receiving antenna D3 for a predetermined period. When the RF receiving antenna D3 receives the response signal, the control unit 10 acquires the RF signal strength of the received response signal through the RF receiving circuit 21 (step S103). The control unit 10 stores the acquired RF signal strength and the identification information of the RF receiving antenna D3 in the storage unit 13 in association with each other.
　例えば、いずれのＲＦ信号強度も取得できない場合は、制御部１０は、ＲＦ受信アンテナＤ１、すなわち導線２４ａへ接続を切り替える旨の切替制御信号を切替部２２に出力する。切替部２２は、前記切替制御信号に基づき、導線２４ｃから導線２４ａへ接続の切替えを行う。そして、制御部１０は、ステップＳ１０１の処理に戻る。 For example, when any of the RF signal strengths can not be acquired, the control unit 10 outputs, to the switching unit 22, a switching control signal to switch the connection to the RF receiving antenna D1, that is, the lead 24a. The switching unit 22 switches the connection from the conducting wire 24c to the conducting wire 24a based on the switching control signal. Then, the control unit 10 returns to the process of step S101.
　次いで、制御部１０は、記憶部１３に記憶されているＲＦ信号強度を読み出し、夫々のＲＦ信号強度を比較し（ステップＳ１０４）、どのＲＦ信号強度が最も強いかの判定を行う（ステップＳ１０５）。 Next, the control unit 10 reads the RF signal strengths stored in the storage unit 13, compares the respective RF signal strengths (step S104), and determines which RF signal strength is the strongest (step S105). .
　以下においては、説明の便宜上、ＲＦ受信アンテナＤ１に係るＲＦ信号強度が最も強いと判定された場合を例に説明する。 In the following, for convenience of explanation, a case where it is determined that the RF signal strength related to the RF receiving antenna D1 is the strongest will be described as an example.
　夫々のＲＦ信号強度を比較した結果、ＲＦ受信アンテナＤ１に係るＲＦ信号強度が最も強いと判定されたので、制御部１０は、ＲＦ受信アンテナＤ１、すなわち導線２４ａへ接続を切り替える旨の切替制御信号を切替部２２に出力する（ステップＳ１０６）。切替部２２は、前記切替制御信号に基づき、接続を導線２４ａへ切り替える。 As a result of comparing the respective RF signal strengths, it is determined that the RF signal strength related to the RF receiving antenna D1 is the strongest, so the control unit 10 controls the switching control signal to switch the connection to the RF receiving antenna D1, that is, the lead 24a. Are output to the switching unit 22 (step S106). The switching unit 22 switches the connection to the conductor 24 a based on the switching control signal.
　切替部２２による切替えによって、ＲＦ受信回路２１と、最もＲＦ信号強度が強い応答信号を受信するＲＦ受信アンテナＤ１との接続が維持される。従って、ＲＦ受信アンテナＤ１を介して、水平偏波指向性によるディップの影響のない、安定した応答信号の受信が可能となる。 The switching by the switching unit 22 maintains the connection between the RF receiving circuit 21 and the RF receiving antenna D1 that receives the response signal with the highest RF signal strength. Therefore, stable reception of response signals without influence of dip due to horizontal polarization directivity can be performed through the RF receiving antenna D1.
　ＲＦ受信回路２１は、ＲＦ受信アンテナＤ１を介して無線端末Ｒからの応答信号を受信し、プリアンブル部の後に受信されるコマンドコード等の復調処理を行い、制御部１０に出力する（ステップＳ１０７）。制御部１０は、斯かるコマンドコードに基づき、ドアロック装置、ドアミラー装置、車内灯及びハザードランプ等の各装置に前記動作指示信号を入出力部１２を介して出力する（ステップＳ１０８）。 The RF receiving circuit 21 receives a response signal from the wireless terminal R via the RF receiving antenna D1, performs demodulation processing of a command code and the like received after the preamble unit, and outputs the result to the control unit 10 (step S107). . Based on the command code, the control unit 10 outputs the operation instruction signal to each device such as a door lock device, a door mirror device, an interior light, a hazard lamp, etc. via the input / output unit 12 (step S108).
　なお、例えば、何れかのＲＦ受信アンテナによる応答信号の受信ができず、ＲＦ信号強度の取得ができていない場合が起こり得る。これは、斯かる応答信号を送信した無線端末Ｒが、当該ＲＦ受信アンテナの前記不感領域に位置していることを意味する。従って、他の何れかのＲＦ受信アンテナへの切替により、安定した通信状態を確保することができる。 In addition, for example, the case where the response signal can not be received by any of the RF receiving antennas and the RF signal strength can not be obtained may occur. This means that the wireless terminal R which has transmitted such a response signal is located in the dead zone of the RF receiving antenna. Therefore, stable communication can be ensured by switching to any other RF receiving antenna.
　このような構成によって、本実施形態の車載アンテナ装置１００は、夫々のＲＦ受信アンテナＤ１，Ｄ２，Ｄ３のディップＳ２による不感領域を相互補完し、安定した通信状態を確保し、安定的に応答信号を受信することができる。 With such a configuration, the on-vehicle antenna device 100 of the present embodiment mutually complements the dead area due to the dips S2 of the respective RF receiving antennas D1, D2 and D3, secures a stable communication state, and stably responds Can be received.
　今回開示された実施形態はすべての点で例示であって、制限的なものではないと考えられるべきである。本発明の範囲は、上記した意味ではなく、請求の範囲によって示され、請求の範囲と均等の意味及び範囲内でのすべての変更が含まれることが意図される。 The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is indicated not by the meaning described above but by the scope of the claims, and it is intended to include all the modifications within the meaning and scope equivalent to the scope of the claims.
　２２　切替部
　２５ａ，２５ｂ　アンテナエレメント
　３１　ＬＦ送信回路　
　３３ａ，３３ｂ　インダクタ
　１００　車載アンテナ装置
　Ａ１，Ａ２，Ａ３　ツイストペア線
　Ｃ１，Ｃ２　キャパシタ
　Ｄ１，Ｄ２，Ｄ３　ＲＦ受信アンテナ
　Ｔ１，Ｔ２，Ｔ３　ＬＦ送信アンテナ
　Ｖ　車両
　Ｗ　右側窓 22 switching unit 25a, 25b antenna element 31 LF transmission circuit
33a, 33b Inductor 100 Car antenna system A1, A2, A3 Twisted pair wire C1, C2 Capacitor D1, D2, D3 RF receiving antenna T1, T2, T3 LF transmitting antenna V Vehicle W right window

Claims (6)

  1. 　車両の外部からＲＦ受信信号を受信する複数のＲＦ受信アンテナを備える車載アンテナ装置において、
    　前記複数のＲＦ受信アンテナは、
    　前記ＲＦ受信信号を受信するＲＦ受信アンテナ素子が透視可能材料からなり、
    　少なくとも一つの他のＲＦ受信アンテナと水平偏波指向性が異なる、一のＲＦ受信アンテナを含み、
    　前記複数のＲＦ受信アンテナのうち、何れかのＲＦ受信アンテナを選択する選択部を備える車載アンテナ装置。     In an on-vehicle antenna device comprising a plurality of RF receiving antennas for receiving an RF receiving signal from the outside of a vehicle,
    The plurality of RF receiving antennas are
    The RF receiving antenna element for receiving the RF receiving signal is made of a see-through material,
    Including one RF receive antenna that differs in horizontal polarization directivity from at least one other RF receive antenna,
    An on-vehicle antenna device comprising: a selection unit that selects any one of the plurality of RF reception antennas.
  2. 　前記一のＲＦ受信アンテナと、前記他のＲＦ受信アンテナは、夫々の水平偏波指向性によるディップの方向が異なる請求項１に記載の車載アンテナ装置。 The on-vehicle antenna device according to claim 1, wherein the one RF receiving antenna and the other RF receiving antenna have different dip directions due to respective horizontal polarization directivity.
  3. 　各ＲＦ受信アンテナは、向かう方向が異なる前記車両の窓に夫々設けられている請求項１又は２に記載の車載アンテナ装置。 The on-vehicle antenna device according to claim 1 or 2, wherein the respective RF receiving antennas are respectively provided in windows of the vehicle which are different in the direction of the direction.
  4. 　前記ＲＦ受信信号と周波数が異なるＬＦ送信信号を外部に送信する複数のＬＦ送信アンテナと、
    　前記ＬＦ送信アンテナに前記ＬＦ送信信号を送り、かつ、前記ＲＦ受信アンテナを介して前記ＲＦ受信信号を受けるツイストペア線と
    　を備える請求項１から３の何れかに記載の車載アンテナ装置。     A plurality of LF transmission antennas for transmitting to the outside an LF transmission signal different in frequency from the RF reception signal;
    The in-vehicle antenna device according to any one of claims 1 to 3, further comprising: a twisted pair wire that transmits the LF transmission signal to the LF transmission antenna and receives the RF reception signal via the RF reception antenna.
  5. 　前記ＬＦ送信アンテナに前記ＬＦ送信信号を送信するＬＦ送信部を備え、
    　前記ＬＦ送信部は、前記ＲＦ受信信号の流入を防止するインダクタを有する請求項４に記載の車載アンテナ装置。     An LF transmitter configured to transmit the LF transmission signal to the LF transmission antenna;
    5. The on-vehicle antenna device according to claim 4, wherein the LF transmission unit has an inductor that prevents the inflow of the RF reception signal.
  6. 　前記ＬＦ送信信号が前記ＲＦ受信アンテナに流入することを防止するキャパシタを有する請求項４又は５に記載の車載アンテナ装置。 The on-vehicle antenna device according to claim 4 or 5, further comprising a capacitor that prevents the LF transmission signal from flowing into the RF receiving antenna.
PCT/JP2019/000012 2018-01-17 2019-01-04 On-vehicle antenna device WO2019142656A1 (en)

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JP2017079430A (en) * 2015-10-21 2017-04-27 住友電気工業株式会社 Vehicle communication system and on-vehicle device
JP2017203256A (en) * 2016-05-09 2017-11-16 トヨタ自動車株式会社 Electronic key system

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JP2005248427A (en) * 2004-03-01 2005-09-15 Denso Corp Lock-in prevention device
JP2006314071A (en) * 2005-04-04 2006-11-16 Matsushita Electric Ind Co Ltd On-vehicle antenna device
JP2007002654A (en) * 2005-05-26 2007-01-11 Alps Electric Co Ltd Keyless entry device
JP2009084829A (en) * 2007-09-28 2009-04-23 Denso Corp Smart key system
JP2013026697A (en) * 2011-07-15 2013-02-04 Asahi Glass Co Ltd Glass antenna and windowpane
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