JP2008135932A - In-vehicle antenna for etc and etc-incorporated inner mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ETC-incorporated inner mirror which can be fitted to a variety of automobiles without impeding the normal transmission and reception of radio waves by an antenna, and are made easier to be mounted to an automobile. <P>SOLUTION: Disclosed is an in-vehicle antenna for ETC (Electronic Toll Collection) having a patch antenna 11 transmitting and receiving radio waves to and from a road device installed in a gate etc., of a freeway. A conductive base member 7 is fixed to a windshield 2, and an antenna case 15 containing a dielectric substrate 11b where a ground 11a is formed is engaged with the base member 7 fitted to the windshield 2. The antenna case 15 is fitted to the windshield 2 with the dielectric substrate 11b opposed to the base member 7, and then the base member 7 functions as a patch electrode, so that the base member 7 and the dielectric substrate 11b constitute the patch antenna 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ETC (Electronic Toll Collection) built-in inner mirror mounted on a vehicle such as an automobile, and an ETC in-vehicle antenna preferably used for the ETC built-in inner mirror.

Conventionally, an ETC (automatic toll collection system) which is one of so-called DSRC (Dedicated Short-Range Communication) systems has been used.
As an example of this, a radio wave including data such as billing information (usually 5%) between a patch antenna as an in-vehicle antenna for ETC mounted on an automobile (vehicle) and a roadside device provided at a highway gate or the like. .8 GHz band circular polarization is used).

  By the way, a so-called ETC built-in inner mirror in which an on-board device for ETC is integrated with an inner mirror has been developed (see Patent Document 1). As shown in FIG. 4, in this type of ETC built-in inner mirror 50, the patch antenna 51 is accommodated in an antenna case 55 provided in the vicinity of the inner mirror 58 with respect to the windshield 2 of the automobile.

The patch antenna 51 shown in FIG. 4 is formed as follows. That is, a metal such as copper is formed into a thin film on both surfaces of a dielectric substrate 52 having a thickness of about 1 mm made of a dielectric, and the metal thin film on the surface is formed at the center of the dielectric substrate 52. Other thin films are removed leaving a small square portion (hereinafter referred to as “patch electrode 53”). Furthermore, the metal thin films on the front and back surfaces are respectively electrically connected to the inner conductor of the coaxial cable connected to the high frequency power source and the grounded outer conductor (not shown).
JP 2006-197429 A

  However, according to the above-described prior art, as shown in FIG. 4, the antenna case 55 in which the patch antenna 51 is housed is usually disposed above the stay 56. It is difficult to mount the ETC built-in inner mirror 50 on a vehicle type that does not have sufficient space. Further, since the antenna case 55 and the stay 56 are separated from each other, when the inner mirror 50 with a built-in ETC is mounted on a car, it is necessary to attach the antenna case 55 and the stay 56 to the windshield 2 individually. The installation work becomes complicated.

  On the other hand, when the ETC built-in inner mirror 50 is attached to the windshield 2 via the base member 57 (button for attaching the inner mirror) made of a conductive material, the patch is placed close to the base member 57. By arranging the antenna 51, a method for reducing the size of the antenna case 55 and solving the above problems can be considered. However, in this method, radio waves are absorbed and reflected by the base member 57, and normal transmission / reception of radio waves by the patch antenna 51 is prevented.

  The present invention has been made to solve the above-described problems, and its purpose is to enable mounting on various vehicles without interfering with normal transmission and reception of radio waves by an antenna, and mounting on vehicles. It is an object of the present invention to provide an ETC built-in inner mirror that can be easily operated, and an ETC in-vehicle antenna that is preferably used for the ETC built-in inner mirror.

  In order to solve the above problems, the invention according to claim 1 is provided with a patch antenna mounted on a vehicle and configured to transmit / receive radio waves to / from a roadside device provided at a highway gate or the like. An ETC (automatic charge) attached to the windshield by engaging a case member containing a dielectric substrate having a conductive base member fixed to the windshield and having a ground formed on one side thereof. In the in-vehicle antenna for receiving system, the case member is attached to the windshield so that the dielectric substrate faces the base member, so that the base member functions as a patch electrode, and the base member and the dielectric The gist is that the patch antenna is configured with a body substrate.

  According to this configuration, the base member that has been conventionally used only for attaching the inner mirror also functions as the patch electrode of the patch antenna. As a result, the base member and the dielectric substrate are arranged close to each other.

  According to a second aspect of the present invention, in the ETC in-vehicle antenna according to the first aspect, the case member is integrally formed with a base end portion of a stay that supports an inner mirror of the vehicle, and the case member The gist of the invention is that there is provided a fitting / fixing means having a slide groove for slidably fitting the peripheral edge portion of the patch electrode and a fixing portion for fixing the patch electrode at a predetermined position.

  According to this configuration, the patch electrode (corresponding to a conventional base member) fixed to the windshield of the vehicle is fitted into the slide groove of the fitting fixing means of the case member (stay), and along the slide groove The stay can be attached to the windshield by sliding and further fixing at the fixing portion of the fitting fixing means. For this reason, the work of attaching the ETC built-in inner mirror to the windshield is simplified.

  According to a third aspect of the present invention, there is provided an ETC (automatic toll collection system) built-in inner that includes an inner mirror of a vehicle and a patch antenna that transmits and receives radio waves between a roadside device provided at a highway gate and the like The mirror further includes a case member configured to be integrated with a base end portion of the stay supporting the inner mirror and having a dielectric substrate formed with a ground on one side, and the case member includes a front part of the vehicle. The inner mirror is attached to the vehicle body by being engaged with a conductive base member fixed to the glass, and further, the case member is attached to the windshield so that the dielectric substrate faces the base member. By being attached, the base member functions as a patch electrode, and the patch antenna is formed by the base member and the dielectric substrate. That have been made, and the gist.

  According to this configuration, in the ETC built-in inner mirror, the base member that has been conventionally used only for attaching the inner mirror functions as a patch electrode of the patch antenna. Thereby, the base member and the dielectric substrate are arranged close to each other, and the base end portion of the stay that supports the inner mirror and the case member that accommodates the dielectric substrate can be integrally configured. That is, the dielectric substrate of the patch antenna can be accommodated in the base end portion of the stay. As a result, the area where the case member is conventionally disposed on the vehicle upper side of the stay becomes unnecessary, and the ETC built-in inner mirror can be mounted even on a vehicle type in which the area is narrow, and the inner mirror is supported. By attaching the stay to the vehicle, the case member can be attached to the vehicle at the same time, and the work of mounting the ETC built-in inner mirror on the vehicle is simplified. In addition, when arranged in the vicinity of the patch electrode, since the base member that interferes with normal radio wave transmission and reception is shared with the patch electrode of the patch antenna, such a radio wave interference phenomenon does not occur, Stable transmission / reception of radio waves is performed.

  According to the present invention, an ETC built-in inner mirror that can be mounted on various vehicles without interfering with normal transmission and reception of radio waves by an antenna, and can be easily mounted on a vehicle, and the ETC built-in inner mirror An in-vehicle antenna for ETC that is preferably used can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
The inner mirror with built-in ETC according to the present embodiment is obtained by integrating a patch antenna as an in-vehicle antenna for an ETC (automatic toll collection system) into an inner mirror of an automobile (vehicle).

  As shown in FIG. 1, the ETC built-in inner mirror 10 is housed in an antenna case 15 (case member) attached to a windshield 2 of an automobile and the antenna case 15 for transmitting and receiving radio waves to and from a communication terminal outside the vehicle. The patch antenna 11 is provided.

  The antenna case 15 has a bottom member 12 fixed to the windshield 2 via a base member 7 attached (fixed) to the windshield 2 with an adhesive or the like, and is fixed to the bottom member 12 and is provided inside. And a case main body 13 having an accommodating space for accommodating the patch antenna 11.

  As shown in FIGS. 2A and 2B, the patch antenna 11 includes a rectangular dielectric substrate 11b made of epoxy resin (dielectric). The dielectric substrate 11b is held and fixed in a parallel state facing the base member 7 by a holding member 13a constituting a part of the case body 13 (see FIG. 1). On one surface (back surface, one surface) of the dielectric substrate 11b, a ground 11a is formed in a thin film shape over the entire surface. Further, in the central region of the other surface (front surface) of the dielectric substrate 11b, a rectangular power supply film 11c is formed on the base member 7 with a predetermined separation distance (preferably about 2 mm). . The ground 11a and the power feeding film 11c are both formed on the front and back surfaces of the dielectric substrate 11b using a metal material such as copper by an existing printed wiring technique.

  As shown in FIGS. 2A and 2B, an outer conductor 18a of a flexible coaxial cable 18 is electrically connected to the ground 11a. The ground 11a is grounded via the external conductor 18a (it is kept at a potential of 0V). On the other hand, an inner conductor 18b of the coaxial cable 18 is electrically connected to the feeding film 11c, and a high frequency voltage is applied from the transmission / reception module 17 via the inner conductor 18b. Then, by applying the high-frequency voltage to the power supply film 11c in this manner, the high-frequency voltage is applied to the base member 7 that is disposed in the vicinity of the power supply film 11c and is not electrically connected but is electromagnetically coupled. A current is fed (capacitive feed), and circularly polarized waves are radiated from the base member 7.

  Returning to FIG. 1, the ETC built-in inner mirror 10 further includes an inner mirror device 14 provided with an inner mirror 14a for rearward viewing, and supports the inner mirror device 14 with a tip portion 16a. By providing the portion 16 b, the support direction of the inner mirror device 14 is variable, and the base end portion 16 c includes a stay 16 that is integrally formed with the case body 13 of the antenna case 15. The stay 16 can freely change the rear viewing state by the inner mirror 14a. The inner mirror device 14 is hollowed to form a housing part 14b for housing a circuit board and the like, and the transceiver module 17 constituting a part of the ETC built-in inner mirror 10 is provided in the housing part 14b. Contained. The transmission / reception module 17 is connected to a battery unit (not shown) of an automobile via a power supply cable 19 having a connectable / disconnectable connector part 19a so as to be able to supply power, and via a coaxial cable 18. The patch antenna 11 is electrically connected to the feeding film 11c.

  The inner mirror 10 with a built-in ETC according to the present embodiment has a case member 15 constituting a part thereof engaged with a conductive base member 7 fixed to a windshield 2 of an automobile, and a dielectric housed therein. The base member 7 conventionally used for attaching the antenna case 15 to the windshield 2 is attached to the windshield 2 (vehicle body) so that the substrate 11 b faces the base member 7. It is characterized in that it also functions as a part of the patch electrode. In other words, the base member 7 as a patch electrode is fixed to the windshield 2 of the automobile, and the antenna case 15 is attached to the windshield 2 via the patch electrode 7. Have. In detail, the base member 7 is a square plate made of a metal such as copper or iron having a predetermined thickness (thickness is preferably 0.3 mm or more and 3 mm or less) (a square shape having a side of 10 mm or more and 30 mm or less). A plate material is preferable.). 1 and 3, the bottom member 12 of the antenna case 15 is provided with a slide groove 12b for slidably fitting the peripheral edge portions 7a and 7b of the base member 7 and the base member 7 in a predetermined manner. A fitting fixing part 12a (fitting fixing means) having a fixing part 12c fixed at a position is provided.

According to the vehicle-mounted antenna for ETC and the inner mirror with built-in ETC according to this embodiment, the following functions and effects can be obtained.
(1) In the ETC built-in inner mirror, a base member that has been conventionally used only for attaching the inner mirror to the vehicle body also functions as a patch electrode of the patch antenna 11. Thereby, the base member 7 and the dielectric substrate 11b are arranged close to each other, the base end portion 16c of the stay 16 that supports the inner mirror device 14 (inner mirror 14a), and the antenna case 15 that accommodates the dielectric substrate 11b. Can be configured integrally. That is, the dielectric substrate 11 b of the patch antenna 11 can be accommodated in the base end portion 16 c of the stay 16. As a result, the area where the antenna case 15 is conventionally provided on the vehicle upper side of the stay 16 is not required, and the ETC built-in inner mirror 10 can be mounted even in a vehicle type in which the area is narrow. By attaching the stay 16 supporting 14a to the automobile, the antenna case 15 can be attached to the automobile at the same time, and the mounting operation of the ETC built-in inner mirror 10 on the automobile is simplified. Moreover, when the base member 7 is disposed in the vicinity of the base member 7, the base member that interferes with normal radio wave transmission / reception is shared with the base member 7 of the patch antenna. And stable transmission and reception of radio waves will be performed.

  (2) The base member 7 that also functions as a patch electrode fixed to the windshield 2 of the automobile is fitted into the slide groove 12b of the fitting fixing portion 12a of the antenna case 15 (stay 16), and the slide groove 12b The stay 16 can be attached to the windshield 2 by being slid along and fixed by the fixing portion 12c of the fitting fixing portion 12a. For this reason, the attachment work to the windshield 2 of the ETC built-in inner mirror 10 is simplified. The above embodiment may be modified as follows.

  In the above embodiment, the transmission / reception module 17 is accommodated in the inner mirror device 14. However, the present invention is not limited to this, and the transmission / reception module 17 can also be provided at a distance from the inner mirror device 14. As a result, the inner mirror device 14 is configured to be lightweight, and the structure of the device 14 can be simplified.

  In the above-described embodiment, the base member 7 is not directly fed with power, but the base member 7 is circularly polarized ( Radio waves). However, the present invention is not limited to this, and a power feeding point may be provided directly on the base member 7 and radio waves may be radiated from the base member 7 by feeding a high-frequency current to the power feeding point.

  In the above embodiment, the base member 7 and the patch antenna 11 are separated from each other by the bottom member 12 and the holding member 13a. However, rectangular through holes are communicated with the bottom member 12 and the holding member 13a, respectively. The base member 7 and the patch antenna 11 may face each other through the through holes.

The principal part sectional view of the ETC built-in inner mirror concerning the embodiment of the present invention. (A) is a top view of the patch antenna used for the ETC built-in inner mirror concerning the embodiment of the present invention, and (b) is an AA arrow sectional view of the patch antenna. The fitting state figure of the bottom member and patch electrode (base member) of the antenna case concerning embodiment of this invention. Sectional drawing which shows the structure of the inner mirror with a built-in ETC concerning a prior art.

Explanation of symbols

  2 ... windshield, 7 ... base member (patch electrode), 11 ... patch antenna, 11a ... ground, 11b ... dielectric substrate, 15 ... antenna case, 16 ... stay.

Claims (3)

Equipped with a patch antenna that is mounted on a vehicle and transmits and receives radio waves to and from roadside devices installed at highway gates, etc.
An ETC attached to the windshield by engaging a case member that accommodates a dielectric substrate having a conductive base member fixed to the windshield of the vehicle and having a ground formed on one side thereof. In-vehicle antenna for automatic toll collection system)
The case member is attached to the windshield so that the dielectric substrate faces the base member, so that the base member functions as a patch electrode, and the patch antenna is formed by the base member and the dielectric substrate. An in-vehicle antenna for ETC, characterized in that it is configured. The in-vehicle antenna for ETC according to claim 1,
The case member is integrally formed with a base end portion of a stay that supports an inner mirror of the vehicle, and a slide groove that slidably fits the peripheral edge portion of the patch electrode to the case member, and the patch electrode A vehicle-mounted antenna for ETC, provided with a fitting and fixing means having a fixing portion for fixing the antenna at a predetermined position. In an ETC (automatic toll collection system) built-in inner mirror equipped with a patch antenna that transmits and receives radio waves between the inner mirror of the vehicle and a roadside device provided at the gate of an expressway,
A case member that accommodates a dielectric substrate that is integrally formed with a base end portion of the stay that supports the inner mirror and that has a ground formed on one surface;
The inner mirror is attached to the vehicle body by engaging the case member with a conductive base member fixed to the windshield of the vehicle.
The case member is attached to the windshield so that the dielectric substrate faces the base member, so that the base member functions as a patch electrode, and the patch antenna is formed by the base member and the dielectric substrate. An ETC built-in inner mirror characterized by being constructed.

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