JP2015065567A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device which achieves downsizing with a simple structure while forming a polarization plane of an antenna in multiple directions.SOLUTION: An antenna device 1 includes: a first printed wiring board 11 having a substrate 110 and a first antenna element 111 and a ground part 112 which are formed on the substrate 110 by a print pattern; and a second printed wiring board 21 including a substrate 210 standing in a direction in which a surface of the substrate 110 faces and a second antenna element 211 formed on the substrate 210 by a print pattern. The first antenna element 111, the second antenna element 211, and the ground part 112 are electrically connected to form a loop antenna 30.

Description

  The present invention relates to an antenna device.

  As a conventional antenna device, for example, there is one disclosed in Patent Document 1. The antenna device according to Patent Document 1 includes a loop antenna configured by electrically connecting a three-dimensional conductive plate to an antenna portion of a printed pattern formed on a printed board. With this configuration, since the polarization plane of the antenna can be configured in a plurality of directions, it is possible to reduce the influence of multipath in radio wave transmission.

Japanese Patent No. 3445644

  By the way, generally, when downsizing an antenna with respect to a used frequency, a method of obtaining a wavelength shortening effect by bringing a dielectric having a high dielectric constant close to the antenna is used. In the antenna device according to Patent Document 1, the plane of polarization of the antenna can be configured in a plurality of directions. However, in order to reduce the size of the antenna, an attempt is made to obtain a wavelength shortening effect by connecting a dielectric to a conductive plate. In some cases, a dielectric is required and the structure becomes complicated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an antenna device that can be easily miniaturized with a simple configuration while the polarization plane of the antenna is configured in a plurality of directions. .

In order to achieve the above object, an antenna device according to the present invention includes:
A first printed wiring board having a first substrate and a first conductive portion formed on the first substrate by a printed pattern;
A second substrate that stands in a direction in which a surface on which the first conductive portion of the first substrate is formed faces; and a second conductive portion that is formed on the second substrate by a print pattern. A second printed wiring board,
The first conductive portion and the second conductive portion are electrically connected to constitute a loop antenna.
It is characterized by that.

  According to the present invention, it is possible to provide an antenna device that can be easily miniaturized with a simple configuration while the polarization plane of the antenna is configured in a plurality of directions.

(A) is a block diagram of the vehicle equipment which concerns on one Embodiment of this invention. (B) is a block diagram of a portable device according to an embodiment of the present invention. 1 is an external view of an antenna device according to an embodiment of the present invention. (A) is a flowchart of the remote operation process which the control means of a vehicle equipment performs. (B) is a flowchart of a remote operation process executed by the control means of the portable device.

  An antenna device according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1A, the antenna device 1 according to the present embodiment is configured as a part of an in-vehicle device A mounted on a vehicle. The in-vehicle device A constitutes an immobilizer unit together with a portable device B (see FIG. 1B) that is mainly carried by a user who is a driver of the vehicle. The immobilizer unit is for performing predetermined processing (for example, permitting engine start, unlocking, etc.) on the vehicle by operating the portable device B by wireless remote control. . In the present embodiment, the in-vehicle device A is configured as a part of an instrument device for a vehicle such as a motorcycle or an automobile.
Below, after demonstrating schematic structure of the vehicle equipment A and the portable apparatus B, the structure of the antenna apparatus 1 is demonstrated in detail.

(In-vehicle device A)
As shown in FIG. 1A, the in-vehicle device A includes an antenna device 1, a control unit 2 and a display unit 3. The in-vehicle device A is mounted on the circuit board of the instrument device, and operates with electric power from the in-vehicle battery.

  The antenna device 1 is a magnetic field detection type antenna device, and includes a wireless module 1a, a matching circuit 1b, and an antenna 1c. The wireless module 1a is a circuit that modulates various signals (request signals and confirmation signals described later) into radio waves in the UHF (Ultra High Frequency) band and outputs them under the control of the control means 2. Further, the wireless module 1a demodulates an identification signal (indicating an identification code described later) input via the antenna 1c and the matching circuit 1b so as to be read by the control means 2. The matching circuit 1b and the antenna 1c will be described later in detail.

  The control means 2 comprises a microcomputer that performs arithmetic processing based on a predetermined program. The control means 2 includes a storage unit 2a and an authentication processing unit 2b. The storage unit 2a includes a nonvolatile storage medium such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory. The storage unit 2a stores data such as an authentication code corresponding to the identification code and a program for executing remote operation processing. The authentication processing unit 2 b is a functional unit that performs authentication processing based on the identification code acquired from the portable device B via the antenna device 1. The authentication processing unit 2b executes processing for determining whether or not the identification code from the portable device B matches the authentication code stored in the storage unit 2a. The control unit 2 controls the antenna device 1 based on the authentication processing result by the authentication processing unit 2b and transmits a radio signal (request signal or confirmation signal) to the portable device B. The control unit 2 causes the display unit 3 to display notification information such as the vehicle speed and the accumulated travel distance based on vehicle information input from an external device such as an ECU (Electronic Control Unit). The control means 2 is mounted on a first printed wiring board 11 described later.

  The display means 3 is a display that also serves as an instrument device including a liquid crystal display, an organic EL (Electro-Luminescence) display, and the like. Under the control of the control means 2, the display means 3 displays the result of authentication by the authentication processing unit 2b, notification information, and the like.

(Portable machine B)
As shown in FIG. 1B, the portable device B includes an antenna device 4, a control unit 5, an input unit 6, and an indicator lamp 7. For example, the portable device B operates with electric power from a storage battery housed in the housing.

  The antenna device 4 is a magnetic field detection type antenna device, and includes a wireless module 4a, a matching circuit 4b, and an antenna 4c. The wireless module 4a is a circuit that modulates the identification code stored in the control means 5 into a radio wave in the UHF band and outputs it as an identification signal. The identification code is a code indicating that the portable device B corresponds to the in-vehicle device A. Further, the radio module 4a demodulates a radio wave signal (request signal or confirmation signal) input via the antenna 4c and the matching circuit 4b so as to be read by the control means 5. The matching circuit 4b is a circuit corresponding to the input / output setting of the wireless module 4a, and includes a capacitor, a coil, and the like. The antenna 4c is made of, for example, a conductive pattern formed on a circuit board (not shown) included in the portable device B.

  The control means 5 is composed of a microcomputer and includes a storage unit 5a. The storage unit 5a is composed of a non-volatile recording medium, and stores data such as an identification code and a program for executing remote operation processing described later. Based on the operation signal from the input unit 6, the control unit 5 modulates the identification signal including the identification code into a UHF band radio wave so as to be emitted from the antenna device 4. The control means 5 reads a signal (request signal or confirmation signal) input and demodulated via the antenna device 4 and controls the indicator lamp 7 based on this signal.

  The input unit 6 includes, for example, a button switch, detects a pressing operation by the user, and outputs it to the control unit 5 as an operation signal.

  The indicator lamp 7 is a light emitting diode that is turned on / off under the control of the control means 5 and is provided so that the lighting state can be confirmed from the outside.

  From here, with reference to FIG. 2, the structure of the antenna apparatus 1 with which the onboard equipment A is provided is demonstrated in detail. Hereinafter, description will be made as appropriate based on the XYZ coordinate system shown in FIG. In this coordinate system, an axis extending in the thickness direction of the substrate 110 to be described later is the Z axis.

(Antenna device 1)
The antenna device 1 includes a first circuit board 10 and a second circuit board 20.
The first circuit board 10 includes a first printed wiring board 11, connector elements C1, D1, matching circuit elements 12, 13, 14, a tuning capacitor 15, and the above-described wireless module 1a. The first circuit board 10 can also be used as a circuit board of an instrument device in which the in-vehicle device A is incorporated.
The second circuit board 20 includes a second printed wiring board 21 and connector elements C2 and D2.

The first printed wiring board 11 has various wirings printed on a substrate 110, and includes a first antenna element 111 which is a conductive portion made of a printed pattern, and a ground portion (ground portion) 112.
The second printed wiring board 21 includes a second antenna element 211 having a printed pattern on which various wirings are printed on a substrate 210. The second printed wiring board 21 is a separate printed wiring board from the first printed wiring board 11, and is coupled to the first printed wiring board 11 by connectors C and D described later.

  The substrates 110 and 210 are made of, for example, FR4 (Flame Retardant Type 4), and are formed into a plate shape by impregnating a glass fiber cloth with an epoxy resin and performing a heat effect treatment (so-called glass epoxy substrate). The board | substrate 110 and the board | substrate 210 are arrange | positioned so that a mutual main surface (surface in which the conductive pattern was formed) may orthogonally cross. The main surface of the substrate 110 is parallel to the XY plane, and the main surface of the substrate 210 is parallel to the YZ plane.

  The first antenna element 111 and the ground portion 112 are made of a conductive pattern such as a copper foil printed on the substrate 110. The first antenna element 111 is located on one end side (left side in FIG. 2) of the first printed wiring board 11, and is formed in a substantially U-shape when viewed from the Z direction. The ground portion 112 is made of a solid conductive pattern, and has a first portion 112a and a second portion 112b. The first portion 112a is formed to extend to the other end portion side (the right side in FIG. 2) of the first printed wiring board 11, and the second portion 112b is a first antenna in a band shape from the first portion 112b. It is formed to extend toward the element 111 side. Further, the second portion 112b is formed along the lower end of the first printed wiring board 11 in FIG. Thereby, the ground part 112 becomes a substantially L shape seeing from the Z direction. The magnetic flux of the radio wave received by the antenna device 1 penetrates the region (first region) between the first antenna element 111 and the ground portion 112 where the conductive pattern is not formed on the substrate 110. . For this reason, the first antenna element 111 and the ground portion 112 are arranged with an interval for sufficiently securing this region.

  The second antenna element 211 is made of a conductive pattern printed on the substrate 210 by copper foil or the like. As shown in FIG. 2, the second antenna element 211 is formed in a substantially U-shape when viewed from the X direction. A magnetic flux received by the antenna device 1 penetrates an area surrounded by the second antenna element 211 and having no conductive pattern formed on the substrate 210 (second area). Therefore, the second antenna element 211 is patterned so as to sufficiently secure this region.

  The first antenna element 111, the second antenna element 211, and the ground portion 112 are electrically connected, and a loop-shaped loop antenna 30 is configured by these. The loop antenna 30 corresponds to the antenna 1c shown in FIG.

The connector elements C1 and D1 are mounted on the first printed wiring board 11. The connector elements C2 and D2 are mounted on the second printed wiring board 21. The connector elements C1 and C2 are paired, and constitute the connector C, one on the plug (header) side and the other on the receptacle side. Similarly, the connector elements D1 and D2 constitute the connector D.
The connectors C and D are board-to-board connectors (so-called BtoB connectors), and electrically connect the first printed wiring board 11 and the second printed wiring board 21 and physically connect them. Accordingly, the second printed wiring board 21 is fixed to the first printed wiring board 11, and the second printed wiring board 21 comes to stand along the Z-axis direction. In this embodiment, since the antenna device 1 is mounted on a vehicle, if a position shift absorption type (for example, FX30A series manufactured by Hirose Electric Co., Ltd.) is used as the BtoB connector, it can be connected even in a vibration environment. Reliability can be secured.

  The connector elements C1 and D1 are provided at the end of the second printed wiring board 21 opposite to the second portion 112b (upper side in FIG. 2). The connector element C1 is connected to one end of the first antenna element 111. The connector element C2 is connected to one end of the second antenna element 211. As a result, the connector C electrically connects the first antenna element 111 and the second antenna element 211. The connector element D1 is connected to a wiring that is electrically connected to one end of the tuning capacitor 15. The connector element D2 is connected to the other end of the second antenna element 211. Thereby, the connector D electrically connects the second antenna element 211 and the tuning capacitor 15.

  Each of the matching circuit elements 12, 13, and 14 includes a coil, a capacitor, and the like, and the above-described matching circuit 1 b is configured by these and a wiring pattern formed on the first printed wiring board 11. The matching circuit 1b is a circuit corresponding to the input / output setting of the wireless module 1a, and electrically connects the first antenna element 111, the wireless module 1a, and the ground portion 112. Here, the electrical connection includes connection through a circuit element or the like, such as connection between the first antenna element 111 and the ground portion 112. The first antenna element 111 and the second antenna element 211 constituting the loop antenna 30 are connected to the wireless module 1a via the matching circuit 1b. The tuning capacitor 15 is composed of, for example, a chip capacitor, one end of which is connected to the second antenna element 211 via the connector D, and the other end is connected to the ground portion 112. The matching circuit 1b and the tuning capacitor 15 have a role of reducing mismatch loss by performing impedance matching between the loop antenna 30 and the wireless module 1a.

  Note that the matching circuit 1b is not the optimum value for the output setting of the wireless module 1a, but uses a slightly different value of a capacitor or coil, or incorporates attenuation means such as an attenuator, The impedance value may be different from the impedance value on the matching circuit 1b side. Thereby, the transmission distance of various signals can be set to a desired distance (for example, several meters). This desired distance is set to a distance at which the user can carry the portable device B and can start the vehicle. In this case, the impedance value (for example, 40 ohms) on the matching circuit 1b side is set to be smaller than the impedance value (for example, 50 ohms) on the wireless module 1a side. In this example, the matching circuit 1b has a third-order filter structure using the matching circuit elements 12, 13, and 14, but the number of elements can be increased or decreased depending on the matching state. Each element can be connected in series to the first antenna element 111 or can be connected in parallel to the ground portion 112.

  According to the antenna device 1 described above, not only the plane of polarization parallel to the first printed wiring board 11 but also the plane of polarization parallel to the second printed wiring board 21 (that is, the first printed wiring board 11). A loop antenna 30 capable of generating a polarization plane in the thickness direction) can be configured. According to the loop antenna 30, it is possible to transmit and receive radio waves obtained by combining two planes of polarization, so that it is possible to reduce the influence of multipath in radio wave transmission.

  From here, with reference to FIG. 3 (a) (b), the remote operation process which the control means 2 of the onboard equipment A and the control means 5 of the portable device B perform is demonstrated.

  The control unit 2 of the vehicle-mounted device A controls the antenna device 1 while the vehicle is stopped, and transmits a request signal every predetermined time (for example, 50 to 500 milliseconds) (step A1). At this time, the antenna device 1 polls and transmits a request signal that is modulated (for example, frequency shift keying) into a radio signal in the UHF band.

  The portable device B is activated when there is an operation from the input means 6. For example, the control unit 5 of the portable device B starts timing from the time of activation and determines whether or not a predetermined time (for example, 10 seconds) has elapsed since the activation (step B1). When the predetermined time has elapsed (step B1; Yes), the control unit 5 shifts to a stop state so as to suppress power consumption until there is an operation from the input unit 6 again. When the predetermined time has not elapsed (step B1; No), the control unit 5 determines whether or not the request signal is included in the signal demodulated by the wireless module 4a (step B2). When the request signal is included (step B2; Yes), the control unit 5 controls the antenna device 4 to transmit an identification signal using the frequency of the UHF band to the periphery (step B3). At this time, if the portable device B performs modulation (for example, amplitude shift keying) different from the modulation method in the in-vehicle device A, the identification signal can be transmitted, thereby improving the confidentiality. On the other hand, when the request signal is not included (step B2; No), the control unit 5 returns the process to step B1.

  The control means 2 of the in-vehicle device A determines whether or not the identification signal has been received after transmitting the request signal (step A2). When the identification signal is received (step A2; Yes), the control unit 2 demodulates the identification signal by the wireless module 1a and executes an authentication process on the identification code (step A3). When the identification signal is not received (step A2; No), the control unit 2 returns the process to step A1. Subsequently, the control unit 2 modulates and transmits the result of the authentication processing determination (conforming or nonconforming) into a UHF band radio signal by the antenna device 1 (step A4). At the same time, the control means 2 also transmits a confirmation signal to an external device (such as an engine starter control unit or a lock control unit) connected to the instrument device via a harness or the like. Accordingly, for example, if the confirmation signal indicates conformity, the external device is in a state where it can accept the engine start operation, and if the confirmation signal indicates nonconformity, the engine start operation is performed. not allowed. Further, the control means 2 can also display on the display means 3 the result of the authentication process and the fact that the engine can be started.

  When the process of step B3 is executed, the control unit 5 of the portable device B receives the confirmation signal via the antenna device 4 and determines whether or not the authentication result by the in-vehicle device A is appropriate (step B4). If the confirmation signal indicates conformity (step B4; Yes), the control means 5 blinks the indicator lamp 7 for a certain period of time to notify the user that the authentication process has been completed (step B5), and the process ends. To do. On the other hand, if the confirmation signal indicates non-conformity (step B4; No), the control means 5 returns the process to step B1.

The antenna device 1 described above includes a substrate 110, a first printed wiring board having a first antenna element 111 and a ground portion 112 (first conductive portion) formed on the substrate 110 by a printed pattern. 11, a substrate 210 standing in a direction in which a surface on which the printed pattern of the substrate 110 is formed faces, and a second antenna element 211 (second conductive portion) formed on the substrate 210 by the printed pattern. 2 printed wiring boards 21, and the first antenna element 111, the second antenna element 211, and the ground portion 112 are electrically connected to form a loop antenna.
Thereby, the polarization plane of the antenna can be configured in a plurality of directions with a polarization plane parallel to the substrate surface of the first printed wiring board 11 and a polarization plane parallel to the substrate surface of the second printed wiring board 21. It is possible to reduce the influence of multipath of radio wave transmission. Further, since the second antenna element 211 is formed on a glass epoxy substrate having a high dielectric constant (dielectric constant of about 4 to 5), it is not necessary to provide a dedicated dielectric to obtain a wavelength shortening effect. Therefore, it is easy to reduce the size with a simple configuration.

  By the way, a printed wiring board having a desired shape is usually obtained by separating from a large-sized substrate. If the second printed wiring board 21 is configured with the remaining part of the first printed wiring board 11 separated from the large-sized board, not only the manufacturing cost is reduced, but also waste is suppressed, which is environmentally friendly. Can also be considered.

In addition, the antenna device 1 connects the substrate 110 and the substrate 210 and electrically connects the first antenna element 111 and the second antenna element 211, the ground portion 112, and the second antenna. And a connector D for electrically connecting the element 211 to the device 211.
Since it did in this way, in order to fix the 2nd printed wiring board 21 to the 1st printed wiring board 11, it is only necessary to fit a connector part, Therefore Assembling is easy. Further, since the antenna elements constituting the loop antenna are electrically connected by the connector, the tolerance for vibration at the connection location is higher than that of the structure in which the antenna elements are directly connected by solder. Therefore, connection reliability can be ensured. In addition, if a displacement-absorbing connector is used as the board-to-board connector, connection reliability can be further ensured even in a vibration environment.

  The loop antenna 30 described above is used for both transmission and reception, and the antenna performance does not change depending on whether transmission or reception is performed. Further, the present invention is not limited to the above-described embodiment, and various modifications can be made. An example of modification is shown below.

(Modification)
In the above description, the example in which the first printed wiring board 11 and the second printed wiring board 21 are connected using two two-pole type substrate surface mount connectors called connectors C and D is shown. It is not limited to this. The printed wiring boards may be coupled with one connector and the antenna elements may be electrically connected.

  In the above description, an example in which the first antenna element 111 and the second antenna element 211 are formed in a substantially U-shape has been described, but the present invention is not limited thereto. The shape of the antenna may be changed by bending the wiring pattern so that a necessary antenna gain in a desired direction can be obtained, or a parasitic element may be provided. In the above description, the example in which the second printed wiring board 21 is erected perpendicularly to the first printed wiring board 11 has been described, but the present invention is not limited to this. The second printed wiring board 21 may be erected obliquely with respect to the first printed wiring board 11.

  In the above description, an example in which the antenna device 1 configures an antenna device for an immobilizer unit has been described. However, the present invention is not limited to this, and the loop antenna 30 can be applied to an appropriate transmission / reception device. Moreover, you may mount the thing of the structure similar to the loop antenna 30 in the portable device B side.

  In addition, this invention is not limited by the above embodiment and drawing. Changes (including deletion of constituent elements) can be added to the embodiments and the drawings as appropriate without departing from the scope of the present invention.

A ... vehicle-mounted device 1 ... antenna device 1a ... wireless module 1b ... matching circuit 1c ... antenna 10 ... first circuit board 11 ... first printed wiring board 110 ... substrate 111 ... first antenna element 112 ... ground part 20 ... 2nd circuit board 21 ... 2nd printed wiring board 210 ... board 211 ... 2nd antenna element 30 ... loop antenna B ... portable machine C, D ... connector

Claims (4)

A first printed wiring board having a first substrate and a first conductive portion formed on the first substrate by a printed pattern;
A second substrate that stands in a direction in which a surface on which the first conductive portion of the first substrate is formed faces; and a second conductive portion that is formed on the second substrate by a print pattern. A second printed wiring board,
The first conductive portion and the second conductive portion are electrically connected to constitute a loop antenna.
An antenna device characterized by that. The first conductive portion is formed so as to surround a first region which is a region on the first substrate and where a conductive portion is not formed,
The second conductive portion is formed so as to surround a second region which is a region on the second substrate and does not have a conductive portion,
One end of the first conductive portion is electrically connected to one end of the second conductive portion, and the other end of the first conductive portion is electrically connected to the other end of the second conductive portion. Yes,
The antenna device according to claim 1. The board further includes a board-to-board connector for electrically connecting the first conductive part and the second conductive part, and connecting the first board and the second board.
The antenna device according to claim 1 or 2, wherein The surface of the first substrate on which the first conductive portion is formed is orthogonal to the surface of the second substrate on which the second conductive portion is formed.
The antenna device according to any one of claims 1 to 3, wherein