JP2007039914A - Communication equipment for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain communication equipment for a vehicle, which efficiently transfers electric power to RF tags, and which realizes electric power savings. <P>SOLUTION: This communication equipment for the vehicle comprises: the RF tags 2a-2f which are arranged in a plurality of places of the vehicle, which generate electric power by the reception of an electric wave, and which transmit unique tag IDs, possessed by themselves, by using the received electric power; an in-vehicle unit 4 which is installed in the vehicle 1, so as to emit the electric wave to the RF tags 2a-2f; and a portable machine 5 which receives and transmits the tag IDs transmitted by the RF tags 2a-2f. The in-vehicle unit 4 selectively emits the electric wave only in a direction corresponding to the position of each of the RF tags 2a-2f, via an antenna 3 with directivity, and determines the position of the portable machine 5 from the state of the reception of the tag ID from the portable machine 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicular communication device having a function of specifying a position of a portable device such as an electronic key system, and more particularly to a passive entry for easily operating locking and unlocking of a vehicle door only by possessing the portable device. The present invention relates to a technique suitable for application.

  Conventionally, as a communication device for remotely controlling an in-vehicle device of an automobile, the vehicle door is automatically unlocked when the user holding the portable device approaches the vehicle, and the vehicle door is automatically released when the user leaves the vehicle. A vehicular communication device having a function to be locked is proposed.

However, in such a conventional device, in order to prevent the portable device from being locked when the portable device is in the vehicle, measures are taken so that the door is not automatically locked, so the portable device is left in the vehicle. If the user leaves the vehicle while leaving the door, the door will be left unlocked, which is a problem in terms of crime prevention.
Therefore, when the user leaves the vehicle, if the portable device is left behind in the vehicle, it is necessary to notify the user of the state. That is, a function for determining whether the portable device is inside or outside the vehicle is required.

  As a technique for determining whether or not a portable device is in a vehicle (hereinafter referred to as “inside / outside determination technique”), for example, a vehicle communication device using an LF charged wave having a frequency of about 120 KHz to 135 KHz has been proposed. (For example, see Patent Document 1).

According to the inside / outside determination technology using LF charged waves, antennas that emit LF charged waves (hereinafter referred to as “LF band antennas”) are installed at various locations of the vehicle. The vehicle-mounted device is coupled via a wired line to supply power.
Further, the portable device is designed to react when the portable device is present within the predetermined magnetic field intensity of the radiated radio wave from the LF band antenna, and the portable device is determined by the response from the portable device to the designated LF band antenna. The on-vehicle device determines the presence of the.

On the other hand, an RFID (Radio Frequency IDentification) technique is known as a technique for detecting an object using radio waves (see, for example, Non-Patent Document 1).
As technologies related to RFID, there are technologies called by various names such as wireless tags, IC tags, RF tags, ID tags, and the like.
An RFID system is typically composed of an RF tag and a reader / writer, and when both are present within a communicable range, when a radio wave is emitted from the reader / writer to the RF tag, a unique tag ID is transmitted from the RF tag. The reader / writer is configured to obtain presence information of the RF tag and position information based on the tag ID by receiving the tag ID.

  Further, in the vehicle inside / outside determination technology of Patent Document 1 described above, the vehicle-mounted device and the LF band antenna are connected by wire, but the technology of Non-Patent Document 1 is applied and an RF tag is used instead of the LF band antenna. A device that determines the inside / outside of the vehicle using the unique ID of the RF tag by communicating wirelessly between the tag and the vehicle-mounted device is conceivable.

  According to this type of vehicle inside / outside determination apparatus, an RF tag installed at a proper position of a vehicle uses a radio wave power received from an antenna of the vehicle-mounted device, and uses a unique tag ID held by itself as an ID reachable area. The portable device that transmits and transmits the received tag ID to the in-vehicle device, and the in-vehicle device exists in the ID reachable area of the RF tag received from the portable device. Can be determined.

In this case, the RF tags are arranged at a plurality of locations in the vehicle in consideration of the power radiation area from the on-board antenna, and the on-board equipment has a unique ID for each RF tag in the power radiation area. It is designed to supply enough power to transmit.
That is, the vehicle-mounted device radiates radio waves to the power radiation area via the antenna, and the RF tag in the power radiation area transmits each unique ID to a nearby ID reachable area using the received power of the radio waves. The portable device in the ID reachable area receives the unique ID from the RF tag and transmits it to the vehicle-mounted device. Hereinafter, the in-vehicle device determines which RF tag the portable device exists in accordance with which unique ID is received by the portable device, and whether the portable device is present inside or outside the vehicle. Will be judged.

JP 2003-221954 A "RFID Handbook 2nd Edition, Principle and Application of Contactless IC Card (ISBN4-526-05291-4)" (written by Klaus Finkenzeller, Translated by Software Engineering Laboratory, Nikkan Kogyo)

  In a conventional vehicle communication device, in the case of a vehicle inside / outside determination device using RFID, in order to supply radio wave power from an in-vehicle device to a plurality of RF tags, for example, an antenna having a wide directivity with a half width is used. Since radio waves are radiated to all RF tags in the radiation area, when radio waves are radiated from the vehicle-mounted device to each RF tag, radio waves are wasted even in spaces where there are no RF tags. There is a problem that power cannot be efficiently transmitted to only the RF tag.

  The present invention has been made to solve the above-described problems. When an electromagnetic wave is radiated from an in-vehicle device to an RF tag using an antenna having a narrow half width (having sharp directivity), the RF tag An object of the present invention is to obtain a vehicular communication device that can efficiently use electric power in an RF tag by effectively radiating radio waves only to a space in which an RF tag exists.

  A vehicle communication device according to the present invention includes a plurality of RF tags installed at a plurality of locations of a vehicle and transmitting unique tag IDs, an in-vehicle device installed in the vehicle, an antenna connected to the on-vehicle device, and a plurality of antennas. A plurality of RF tags for radiating radio waves to a plurality of RF tags, when the tag ID transmitted by at least one of the RF tags is received and a portable device configured to transmit the received tag ID Each of the plurality of RF tags generates power in response to reception of radio waves radiated from the antenna, and is held by itself. The in-vehicle device emits an ID and selectively radiates radio waves to a plurality of RF tags via the antenna, and the position of the portable device based on the reception state from the portable device and the tag ID received from the portable device. Also determine It is.

  According to the present invention, by selectively radiating radio waves from the vehicle-mounted device through the antenna toward the installation direction of each RF tag, power can be efficiently transmitted to the RF tag, thereby realizing power saving. can do.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a plan view of a vehicle communication apparatus according to Embodiment 1 of the present invention.
In FIG. 1, a plurality of RF tags 2 a to 2 f are installed at appropriate locations in the periphery of the vehicle 1.
The RF tags 2a to 2f are not limited to the illustrated example (six), and an arbitrary number of RF tags can be installed as necessary.

A vehicle-mounted device 4 having an antenna 3 is installed in the vehicle 1.
The antenna 3 connected to the vehicle-mounted device 4 has a sharp directivity in order to radiate radio waves only to the region where each of the RF tags 2a to 2f exists, and is disposed, for example, at a substantially central portion in the vehicle 1.
The portable device 5 is normally possessed by the user (driver) of the vehicle 1 and has a receiving circuit that receives the tag ID and a transmitting circuit that transmits the received tag ID to the vehicle-mounted device 4. .
Thereby, the portable device 5 is configured to transmit the received tag ID when receiving the tag ID transmitted by at least one of the plurality of RF tags 2a to 2f.

In the configuration of FIG. 1, the vehicle-mounted device 4 supplies power by selectively radiating radio waves toward the plurality of RF tags 2 a to 2 f via the antenna 3.
Each of the plurality of RF tags 2 a to 2 f generates power and transmits a tag ID held by itself in response to reception of radio waves radiated from the antenna 3.
The portable device 5 transmits the received tag ID to the in-vehicle device 4 when receiving the tag ID transmitted by at least one of the plurality of RF tags 2a to 2f.

The vehicle-mounted device 4 determines the position of the portable device 5 (inside and outside of the vehicle 1) based on the reception state from the portable device 5 and the tag ID received from the portable device 5.
That is, since the portable device 5 knows which RF tag among the RF tags 2a to 2f has received the unique ID of the RF tag, it can be known which RF tag is near the portable device 5. The position of the portable device can be determined from the received tag ID.

In this case, since the antenna 3 simultaneously radiates radio waves to the plurality of RF tags 2a to 2f, the antenna 3 has a sharp directivity with a narrow half-value width in all directions corresponding to the positions of the plurality of RF tags 2a to 2f. Have.
The frequency characteristics of the RF tags 2a to 2f to be used are suitable near 900 [MHz] or around 2.45 [GHz], but are not necessarily limited to these frequencies. Any high frequency band may be used.
Furthermore, the antenna 3 and the vehicle-mounted device 4 are designed according to the frequency characteristics of the RF tags 2a to 2f.

FIG. 2 is an explanatory view schematically showing the directivity (the pattern shape of the radio wave beam) of the antenna 3 used in Embodiment 1 of the present invention.
2, the antenna 3 radiates a plurality of beams 6a, 6b, 6c,... Having a narrow beam width (half-value width) as power supply radio waves having sharp directivity. Here, for convenience, only three beams 6a, 6b, and 6c are shown, but a number of beams corresponding to the number of RF tags 2a to 2f are emitted.

Each beam 6a, 6b, 6c,... Consists of radio waves that are simultaneously emitted simultaneously.
The antenna 3 may be composed of a plurality of antennas that individually radiate independent beams 6a, 6b, 6c,.
The antenna 3 has a configuration using side lobes in addition to the main beam. For example, the RF tag located at a distance far from the antenna 3 radiates the main beam, and the RF tag located at a distance close to the antenna 3 is used. On the other hand, it may be configured to emit side lobes.

FIG. 3 is a configuration diagram schematically showing the state where the beams 6a to 6f are described in FIG. 1, and shows the relationship between the directivity of the antenna 3 and the arrangement of the RF tags 2a to 2f.
In FIG. 3, the same components as those described above (see FIG. 1) are denoted by the same reference numerals as those described above, and detailed description thereof is omitted.
The direction of each beam 6a-6f radiated | emitted via the antenna 3 from the onboard equipment 4 corresponds with the direction of the presence position of each RF tag 2a-2f.

Next, the operation according to the first embodiment of the present invention will be described with reference to FIG.
First, the antenna 3 is driven and controlled by the vehicle-mounted device 4 and simultaneously radiates radio waves including a plurality of beams 6a to 6f corresponding to the installation directions of all the RF tags 2a to 2f.
At this time, when a plurality of beams 6a to 6f are radiated using side lobes, the main beam (beam 6b or 6e) is directed to the RF tag 2b or RF tag 2e having a relatively large distance from the antenna 3. Directed.
Further, the side lobes are directed to the RF tags 2a, 2c, 2d, and 2f located in the vicinity of the antenna 3.

In this way, the beams 6a to 6f having a narrow directivity with a narrow half-value width are radiated simultaneously as radio waves to all the RF tags 2a to 2f, so that the vehicle-mounted device 4 is directed to the RF tags 2a to 2f. Power can be transmitted efficiently.
The RF tags 2a to 2f that have received the radio waves from the antenna 3 of the vehicle-mounted device 4 have the respective tag IDs held by the RF tags 2a to 2f in the ID reachable area in the vicinity area (range narrower than the power radiation area). send.

At this time, for example, as shown in the figure, if the portable device 5 is present in the vehicle 1 and receives at least one tag ID, the portable device 5 transmits the received tag ID to the vehicle-mounted device 4.
Finally, the vehicle-mounted device 4 receives the tag ID transmitted by the portable device 5 and determines which RF tag the portable device 5 is in based on which tag ID the portable device 5 has received. can do.

Also, the RF tags 2a to 2f are installed only in the interior of the vehicle 1, the ID reachable areas of the RF tags 2a to 2f are set only inside the vehicle 1, and the portable device 5 located outside the vehicle 1 The tag ID cannot be received.
Therefore, even when radio waves are radiated from the antenna 3, if the tag ID is not received from the portable device 5, it can be determined that the portable device 5 is located outside the vehicle 1.
As the antenna 3 having the above functions, for example, a Rotman lens antenna or a sector antenna composed of a plurality of elements can be applied, but is not necessarily limited thereto.

As described above, according to the first embodiment of the present invention, a plurality of tag IDs that are arranged at appropriate positions of the vehicle 1 and that transmit the tag IDs owned by themselves using power generated in response to received radio waves are transmitted. RF tag 2a-2f, vehicle-mounted device 4 that is installed in vehicle 1 and selectively emits radio waves for power supply from antenna 3 in the direction of RF tag 2a-2f, and at least one of RF tags 2a-2f A portable device 5 that transmits the received tag ID when receiving the tag ID transmitted by the one, and using the antenna 3 having sharp directivity, radio waves are transmitted only to the space where the RF tags 2a to 2f are present. Since it is configured to radiate, the transmission power from the antenna 3 can be efficiently used in the RF tags 2a to 2f.
That is, as the antenna 3 of the vehicle-mounted device 4 for operating the RF tags 2a to 2f, by using an antenna having a sharp directivity with a narrow half-value width, power can be efficiently used to achieve power saving. be able to.

Embodiment 2. FIG.
In the first embodiment, the beams 6a to 6f are simultaneously emitted from the antenna 3 of the vehicle-mounted device 4 to the RF tags 2a to 2f. However, the beams 6a to 6f are sequentially emitted in the respective directions of the RF tags 2a to 2f. You may radiate.
4 and 5 are diagrams for explaining a vehicle communication device according to Embodiment 2 of the present invention, and show an explanatory diagram and a configuration diagram when beams 6a to 6f are sequentially emitted.

4 and 5, the same parts as those described above (see FIGS. 2 and 3) are denoted by the same reference numerals as those described above, or “A” after the reference numerals, and detailed description thereof is omitted.
FIG. 4 is an explanatory view schematically showing the directivity (pattern shape of radio wave beam) of the antenna 3A applied to the second embodiment of the present invention.
In FIG. 4, the vehicle-mounted device 4A radiates at least one beam at a time via the antenna 3A, and, for example, in the order indicated by the arrows, a sharp directional beam 6a (dashed line) having a narrow half-value width and a beam 6b (Solid line), beam 6c (dotted line),.

In FIG. 4, a beam 6b (solid line) indicates the direction of the beam currently being emitted, a beam 6a (dashed line) indicates the direction of the beam emitted before a certain time, and a beam 6c (dotted line) indicates the certain time. The direction of the beam emitted after elapse of time is shown.
In this case, at least one of the vehicle-mounted device 4A and the antenna 3A has a function of sequentially scanning the beams 6a, 6b, 6c,..., And the radiation direction of the beams 6a, 6b, 6c,. The beam 6a is changed to the beam 6b, and then the beam 6b is changed to the beam 6c.

The beam scan function may be realized by an electronic S / W scan function or a mechanical H / W scan function.
In FIG. 4, only the three-direction beams 6a, 6b, and 6c are shown for convenience, but an arbitrary number of beams can be formed. Furthermore, beam scanning may be performed while simultaneously radiating a plurality of beams.

FIG. 5 is a configuration diagram schematically showing the relationship between the function of the antenna 3A and the arrangement of the RF tags 2a to 2f during the inside / outside determination processing of the portable device 5.
In FIG. 5, the antenna 3A first radiates the radio wave of the beam 6a in the direction of the RF tag 2a, and then radiates the radio wave of the beam 6b directed in the direction of the RF tag 2b after a certain time has elapsed.
Similarly, the beams 6c, 6d, 6e, and 6f are sequentially emitted in the directions of the RF tags 2c, 2d, 2e, and 2f, respectively, and radio waves are emitted to all the RF tags 2a to 2f.

Thereby, similarly to the above, electric power can be efficiently transmitted from the vehicle-mounted device 4A to the RF tags 2a to 2f.
At this time, for a certain period of time from when one beam is emitted to when the next beam is emitted, the portable device 5 receives the unique tag ID from one RF tag, and the received tag ID is used as the in-vehicle device 4A. It is set to a sufficient time so as to be longer than the time required for replying to.

Next, the operation according to the second embodiment of the present invention will be described with reference to FIGS.
First, as illustrated, when the portable device 5 is present in the vehicle 1, the portable device 5 transmits the tag ID received from any of the RF tags 2a to 2f to the vehicle-mounted device 4A.
Thereby, the onboard equipment 4 can determine which RF tag the portable apparatus 5 exists in the vicinity based on which tag ID the portable apparatus 5 has received.

  Similarly to the above, the RF tags 2a to 2f are installed in the interior of the vehicle 1, and the tag IDs transmitted by the RF tags 2a to 2f cannot be received outside the vehicle 1. 4, when the tag ID cannot be received from the portable device 5, it can be determined that the portable device 5 exists outside the vehicle 1.

In addition, in FIG. 5, the plurality of RF tags 2 a to 2 f do not execute tag ID transmission operations at the same time, but sequentially, thus reducing interference of radio waves between the RF tags 2 a to 2 f. be able to.
Here, for convenience, six RF tags 2a to 2f are shown, but it goes without saying that the number of RF tags can be arbitrarily increased or decreased.
Further, although radio waves (beams 6a to 6f) are radiated clockwise to the RF tags 2a to 2f, the radiation order can be arbitrarily set.

Further, as the antenna 3A having the above scanning function, for example, a phased array antenna is applied, but the present invention is not necessarily limited thereto.
Further, as the antenna 3A that scans the plurality of beams 6a to 6f, for example, a configuration in which two beams are scanned simultaneously may be applied.
Next, the case where the antenna 3A is configured to scan two beams at a time will be described.

In FIG. 5, the vehicle-mounted device 4A first radiates two beams 6a and 6b simultaneously to the RF tags 2a and 2b via the antenna 3A.
Subsequently, after a predetermined time has elapsed, two beams 6c and 6d are simultaneously emitted to the RF tags 2c and 2d.
Hereinafter, similarly, beams 6e and 6f are radiated to the RF tags 2e and 2f, and all the RF tags 2a to 2f are transmitted.

Note that the number of beams that are emitted simultaneously may be set to a value larger than two (for example, three), and the beams can be emitted sequentially to all the RF tags 2a to 2f in the same manner as described above. That's fine.
Moreover, the beam radiated | emitted simultaneously from the onboard equipment 4A does not necessarily need to be a beam which adjoins, and the order of the radiation | emission of the electromagnetic wave to each RF tag 2a-2f can be set arbitrarily.
Finally, the portable device 5 transmits the received tag ID to the vehicle-mounted device 4A, and the portable device 4A determines which RF tag the portable device 5 is in based on which tag ID is received. Can be determined.
As the antenna 3A having the above scanning function, for example, a sector antenna (consisting of a plurality of antenna elements) is applied, but is not necessarily limited thereto.

As described above, according to the second embodiment of the present invention, as described above, as the antenna 3A of the vehicle-mounted device 4, an antenna having a sharp directivity with a narrow half-value width is used, so that power can be efficiently generated. It can be used to save power.
Further, since the electronic or mechanical scanning function is applied and the power supply beams 6a to 6f are sequentially emitted so that all the RF tags 2a to 2f do not operate simultaneously, the RF tag 2a When ~ 2f transmits tag ID simultaneously, the interference which arises between RF tags 2a-2f can be reduced.

It is a block diagram which shows planarly the vehicle communication apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows typically the pattern shape of the radio wave beam radiated | emitted from the antenna by Embodiment 1 of this invention. It is a block diagram which shows typically the radiation state of the electromagnetic wave from the antenna by Embodiment 1 of this invention to RF tag. It is explanatory drawing which shows typically the pattern shape of the radio wave beam radiated | emitted from the antenna by Embodiment 2 of this invention. It is a block diagram which shows typically the radiation state of the electromagnetic wave from the antenna by Embodiment 2 of this invention to RF tag.

Explanation of symbols

  1 vehicle, 2a-2n RF tag, 3, 3A vehicle-mounted antenna, 4, 4A vehicle-mounted device, 5 portable device, 6a-6n beam (radio wave).

Claims (3)

A plurality of RF tags installed in a plurality of locations of the vehicle and transmitting unique tag IDs;
A vehicle-mounted device installed in the vehicle;
An antenna connected to the vehicle-mounted device;
A portable device configured to transmit the received tag ID when receiving a tag ID transmitted by at least one of the plurality of RF tags;
The antenna has directivity in all directions corresponding to the positions of the plurality of RF tags in order to radiate radio waves to the plurality of RF tags.
Each of the plurality of RF tags responds to reception of radio waves radiated from the antenna, generates power and transmits a tag ID held by itself,
The on-vehicle device selectively radiates the radio wave toward the plurality of RF tags via the antenna, and the portable device based on a reception state from the portable device and a tag ID received from the portable device. A vehicle communication device characterized by determining the position of the vehicle.   2. The vehicle according to claim 1, wherein when the antenna radiates radio waves to the plurality of RF tags, the antenna radiates a beam simultaneously in all directions corresponding to the positions of the plurality of RF tags. Communication equipment.   2. The vehicle according to claim 1, wherein when the antenna radiates radio waves to the plurality of RF tags, the antenna sequentially radiates beams in respective directions corresponding to positions of the plurality of RF tags. Communication device.

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