JP4264040B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device in which a patch antenna and a high-frequency circuit are unitized, and in particular, a system that is installed in a tire of an automobile and monitors tire pressure, and other antenna devices suitable for outdoor use. About.

  Conventionally, an antenna device in which a patch antenna and a high-frequency circuit are unitized is known (see, for example, Patent Document 1), and this conventional antenna device will be described with reference to a cross-sectional view shown in FIG. The antenna device shown in the figure is mounted on a circuit board 50 having a wiring pattern 51 formed on one side (the lower surface in the drawing) and a ground pattern 52 formed on the other surface (the upper surface in the drawing), and the one side of the circuit board 50. Various electronic components 53, a sheet metal shield case 54 attached to the one side of the circuit board 50 so as to cover these groups of electronic components 53, and an antenna element mounted on the other side of the circuit board 50 55 is mainly configured. Here, the antenna element 55 includes a dielectric substrate 56 made of ceramic or the like, and a radiation conductor 57 having a predetermined shape formed on a surface (upper surface in the drawing) opposite to the circuit substrate 50 side of the dielectric substrate 56, A ground conductor layer 58 formed on substantially the entire surface of the dielectric substrate 56 on the side of the circuit board 50 (the lower surface in the drawing), and a feed pin that penetrates the dielectric substrate 56 and has one end connected to the feed point of the radiation conductor 57. 59 is a patch antenna. The antenna element 55 is placed on the circuit board 50 and attached by soldering the ground conductor layer 58 to the ground pattern 52. The other end of the power supply pin 59 passes through the circuit board 50 and is connected to the wiring pattern 51, and the power supply pin 59 is kept out of contact with the ground conductor layer 58 and the ground pattern 52.

In such a conventional antenna device, a high-frequency circuit is configured by the wiring pattern 51 and the electronic component 53 group, and the high-frequency circuit and the radiation conductor 57 of the antenna element 55 are connected via the feed pin 59. It is possible to amplify the signal received by the radiating conductor 57 by the high frequency circuit, or to transmit the signal processed by the high frequency circuit from the radiating conductor 57. Further, since this high-frequency circuit is covered with a shield case 54 and electromagnetically shielded, consideration is given so that electromagnetic waves emitted from the group of electronic components 53 do not adversely affect antenna characteristics.
Japanese Patent Laid-Open No. 9-223912 (page 3-4, FIG. 1)

  However, the above-described conventional antenna device is configured by attaching the box-shaped shield case 54 to one side of the circuit board 50 and attaching the antenna element 55 based on the dielectric substrate 56 to the other side of the circuit board 50. Therefore, there is a problem that the overall height dimension increases and it is difficult to reduce the thickness. For this reason, when this type of antenna device is incorporated into a tire of an automobile and applied to a tire pressure monitoring system (TPMS), a complicated assembling work is unavoidable. In addition, such a conventional antenna device has a problem that it cannot be manufactured at low cost because the number of parts is large and the manufacturing process is complicated. Further, in such a conventional antenna device, since waterproof measures for the electronic parts 53 group covered with the shield case 54 are not taken into consideration, there is a problem that malfunction or failure is likely to occur when used outdoors.

  The present invention has been made in view of such a state of the art, and an object of the present invention is to provide an antenna device that can be easily reduced in thickness and is waterproof.

In order to achieve the above object, in the antenna device according to the present invention, a dielectric substrate having a wiring pattern formed on one side and a radiation conductor formed on the other side, and mounted on the one side of the dielectric substrate and An electronic component that constitutes a high-frequency circuit together with a wiring pattern, a feeding means that electrically connects the feeding point of the radiation conductor and the wiring pattern through the dielectric substrate, and the electronic component in a state of covering the electronic component A grounding conductor plate attached to the one side of the dielectric substrate, and a circuit auxiliary board having a larger diameter than the radiation conductor and a component mounting surface on which one side is mounted with a chip component. provided with a concave lid having a storage space of the electronic component, the adhesion is fixed to the one surface of the dielectric substrate over the periphery of the concave lid all around, and the circuit auxiliary board, before It was fixed on the other surface of the dielectric substrate in a state that the component mounting surface was facing the radiation conductor.

In the antenna device configured as described above, the dielectric substrate of the antenna element also serves as the circuit board of the high-frequency circuit, and the ground conductor plate also serves as the shield case. Therefore, the number of components can be reduced and the cost can be reduced. It is possible to reduce the overall thickness of the apparatus. In addition, since the periphery of the concave lid portion of the ground conductor plate is tightly fixed to the dielectric substrate over the entire circumference, the space in the concave lid portion in which the electronic component is stored is surely sealed to improve waterproofness. be able to. In addition, since the built-in high-frequency circuit can be distributed between the dielectric substrate and the circuit auxiliary substrate, the entire apparatus can be reduced in size, and the radiation conductor can be covered and protected by the circuit auxiliary substrate, and the reliability is also improved. improves.

  In the above configuration, a vent hole that connects the space in the concave lid portion and the external space is formed in the ground conductor plate or the dielectric substrate, and the vent hole is formed by a breathable waterproof member having breathability and waterproofness. If closed, it is possible to prevent the occurrence of dew condensation in the concave lid portion of the ground conductor plate without impairing the waterproof property, so that the reliability is further improved and it is suitable for outdoor use. In this case, if the vent hole is formed in the concave lid portion of the ground conductor plate and the breathable waterproof member is attached to the outer surface of the concave lid portion, the work of attaching the vent waterproof member can be performed easily and reliably. Therefore, it is preferable.

  In the above configuration, the ground conductor plate is provided with a flat collar that surrounds the entire open end of the concave lid, and the collar is brought into close contact with the one surface of the dielectric substrate. This is preferable because the work of tightly fixing the periphery of the concave lid portion of the ground conductor plate to the dielectric substrate can be performed easily and reliably.

  In the above configuration, when the electronic component includes a crystal resonator, the crystal resonator can be resonated at a frequency corresponding to the air pressure. Therefore, the antenna device is incorporated in a tire of an automobile. Can be applied to a tire pressure monitoring system. In this case, since the antenna device can be thinned, the assembling work into the tire can be performed relatively easily. If the antenna device is installed near the wheel in the tire and the radiation conductor is directed toward the outer periphery of the tire, the quartz crystal unit is pressed against the mounting surface (dielectric substrate side) by centrifugal force when the tire rotates. Thus, there is no possibility of centrifugal force acting in the direction in which the crystal resonator is pulled away from the mounting surface, which is preferable because malfunction and destruction of the crystal resonator due to the centrifugal force during tire rotation can be prevented.

Further, in the above-described structure, the circuit a detection circuit provided in the component mounting surface of the auxiliary substrate, Rukoto were electrically connecting the wiring pattern and a feeding point of the radiating conductor through the detector circuit is preferred.

  In this case, an opening is formed in the substantially central portion of the radiation conductor, and a concave step portion that protrudes from the opening is formed on the other surface of the dielectric substrate, and the space in the concave step portion is used as a storage space for chip components. If so, the entire device can be made thin without adversely affecting the antenna characteristics, which is preferable.

  In the antenna device according to the present invention, since the dielectric substrate of the antenna element also serves as the circuit board of the high-frequency circuit, and the ground conductor plate also serves as the shield case, the number of parts can be reduced and the cost can be reduced. Thinning of the entire apparatus can be promoted. In addition, since the periphery of the concave lid portion of the ground conductor plate is tightly fixed to the dielectric substrate over the entire circumference, the space inside the concave lid portion in which the electronic components are stored is surely sealed to enhance waterproofness. be able to.

Further, the antenna device according to the present invention can disperse the built-in high-frequency circuit between the dielectric substrate and the circuit auxiliary substrate, so that the entire device can be reduced in size, and the radiation conductor is covered and protected by the circuit auxiliary substrate. Can improve reliability.

An embodiment of the invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an antenna device according to a reference example , and FIG. 2 is an explanatory view showing a mounting structure of a crystal resonator built in the antenna device. 3 is an explanatory view showing a state in which the antenna device is installed in a tire.

  The antenna device 1 shown in these drawings is an antenna unit in which a patch antenna and a high-frequency circuit are unitized, and is installed and used in a tire 20 of an automobile as a transponder for a tire pressure monitoring system. The antenna device 1 is mounted on a dielectric substrate 2 having a wiring pattern 3 formed on one side (the lower surface in the drawing) and a radiation conductor 4 formed on the other surface (the upper surface in the drawing), and the one surface of the dielectric substrate 2. Covers various electronic components 5 constituting a high-frequency circuit together with the wiring pattern 3, power supply pins 6 penetrating the dielectric substrate 2 and having both ends connected to the radiation conductor 4 and the wiring pattern 3, and a group of electronic components 5. In this state, the grounding conductor plate 7 is mainly constituted by the grounding conductor plate 7 attached to the one surface of the dielectric substrate 2, and the grounding conductor plate 7 also serves as a shield case for electromagnetically shielding the high frequency circuit. As shown in FIG. 3, the antenna device 1 is installed in the vicinity of the wheel 21 and the valve 22 in the tire 20, and the radiation conductor 4 faces the outer peripheral side of the tire 20.

  The high-frequency circuit provided on the lower surface side of the dielectric substrate 2 is constituted by a detection circuit, a resonance circuit, or the like, and a crystal resonator 5a that is one of the electronic components 5 is disposed in the resonance circuit. . As shown in FIG. 2, the crystal unit 5a includes a substrate 5b, a conductive path 5c provided on the lower surface of the substrate 5b, and a crystal piece having one end fixed to the conductive path 5c by a conductive adhesive 5d. 5e, a connecting portion 5f connected to the conductive path 5c and led out to the upper surface of the substrate 5b, and an insulating cover 5g attached to the substrate 5b so as to cover the crystal piece 5e. The other end portion (left end portion in the drawing) of 5e is a free end portion. The crystal unit 5 a is mounted on the lower surface of the dielectric substrate 2 in a state where the connection portion 5 f is connected to the wiring pattern 3.

  The radiating conductor 4 is obtained by patterning a copper foil or the like into a predetermined shape, and one end of a feeding pin 6 is connected to the feeding point of the radiating conductor 4. The other end of the power supply pin 6 is connected to the wiring pattern 3 of the high-frequency circuit. Since the radiation conductor 4 is supplied with power through the power supply pin 6, transmission and reception can be performed. The radiation conductor 4 opposes a sheet metal ground conductor plate 7 with the dielectric substrate 2 interposed therebetween, and an antenna element is constituted by the radiation conductor 4, the dielectric substrate 2, the ground conductor plate 7, and the feed pin 6. .

  The ground conductor plate 7 includes a concave lid portion 7a having a storage space for a group of electronic components 5 and a flat flange portion 7b extending around the opening end of the concave lid portion 7a. 7b surrounds the open end of the concave lid portion 7a over the entire circumference. Since the flange portion 7b is tightly fixed to the lower surface of the dielectric substrate 2 with an adhesive, solder, or the like, the space in the concave lid portion 7a in which the electronic component group 5 is accommodated is kept sealed. Waterproofness is ensured. In addition, since the high frequency circuit in which the electronic component group 5 is disposed is completely covered with the ground conductor plate 7 and is electromagnetically shielded, it is considered that the electromagnetic wave emitted from the electronic component group 5 does not adversely affect the antenna characteristics. Yes. However, the concave lid portion 7a is formed with a vent hole 7c for communicating the inner and outer spaces, and a breathable waterproof member 8 having air permeability and waterproofness is adhered to the outer surface of the concave lid portion 7a. This vent hole 7c is blocked. This is a measure for preventing the occurrence of condensation in the concave lid portion 7a without impairing the waterproof property. For example, Gore-Tex (registered trademark) is suitable as the ventilation waterproof member 8. When the flange portion 7b is closely fixed to the dielectric substrate 2 by soldering, a frame-like conductor pattern may be formed on the lower surface of the dielectric substrate 2 in advance.

  In the antenna device 1 configured as described above, the dielectric substrate 2 of the antenna element also serves as a circuit board of the high-frequency circuit, and the ground conductor plate 7 also serves as a shield case that covers the electronic component 5 group. Although not shown, the same antenna device 1 is installed in the vicinity of the wheel 21 (in the vicinity of the valve 22) in each tire 20 of the automobile. When the antenna device 1 in any tire 20 receives an interrogation signal from an interrogator (not shown) provided on the vehicle body side, the crystal piece 5e is excited and the frequency according to the air pressure of the tire 20 is obtained. It is designed to resonate. This resonance signal is superimposed on the high frequency signal and transmitted from the radiation conductor 4 to the interrogator, and the interrogator detects the air pressure of the tire 20 from the frequency of the resonance signal. Therefore, the air pressure of each tire 20 can be displayed on the vehicle body side via each antenna device 1.

As described above, in the antenna device 1 according to the reference example , since the dielectric substrate 2 also serves as a circuit board and the ground conductor plate 7 also serves as a shield case, the number of parts is small, and the manufacturing cost can be reduced correspondingly. The thinning of the entire device is also promoted. In addition, since the electronic component group 5 is housed in the concave lid portion 7a of the ground conductor plate 7 and the flange portion 7b is tightly fixed to the dielectric substrate 2 over the entire circumference, the space in the concave lid portion 7a is reduced. It is securely sealed and has a waterproof property suitable for outdoor use. Moreover, the ventilation hole 7c formed in the concave lid portion 7a is closed with the ventilation waterproofing member 8, thereby preventing the occurrence of condensation in the concave lid portion 7a and improving the reliability. In addition, the operation | work which closely fixes the flat collar part 7b to the one surface of the dielectric substrate 2, and the operation | work which sticks the ventilation waterproofing member 8 to the outer surface of the concave cover part 7a can be performed easily and reliably.

  Further, since the antenna device 1 is thinned, the assembling work into the tire 20 can be performed relatively easily. In addition, since the antenna device 1 is installed in the tire 20 in the vicinity of the wheel 21 and the valve 22 with the radiation conductor 4 facing the outer peripheral side of the tire 20, centrifugal force is generated when the tire 20 rotates. There is no worry of adversely affecting the child 5a. That is, the centrifugal force that acts on the crystal resonator 5a by the rotation of the tire 20 is a force in a direction (arrow A direction in FIG. 3) that presses the crystal piece 5e against the mounting surface side (dielectric substrate 2 side). Since there is no possibility that centrifugal force acts in the direction in which the piece 5e is pulled away from the mounting surface, malfunction and destruction of the crystal unit 5a due to centrifugal force during rotation of the tire 20 can be prevented, and reliability is increased.

In the antenna device 1 according to the reference example described above, the case where the vent hole 7c is formed in the concave lid portion 7a has been described. However, a similar vent hole is formed in the dielectric substrate 2 and the space in the concave lid portion 7a is formed. The outer space may be communicated with the outside space, and in this case as well, the condensation can be prevented from occurring in the concave lid portion 7a by closing the ventilation hole with the ventilation waterproofing member 8. Further, since the antenna device 1 is installed in the tire 20, it is possible to measure not only the air pressure but also the temperature in the tire 20 and transmit it to the interrogator on the vehicle body side.

FIG. 4 is a cross-sectional view of the antenna device according to the embodiment of the present invention, and FIG. 5 is a plan view showing the antenna device with the circuit auxiliary board omitted, and the parts corresponding to those in FIGS. Since the reference numerals are attached, overlapping explanation is omitted.

As shown in FIG. 4, the antenna device 10 according to this embodiment includes a circuit auxiliary substrate 11 that covers the radiation conductor 4 and is connected to the wiring pattern 3, and the circuit auxiliary substrate 11 is placed on the dielectric substrate 2. The antenna device 1 is greatly different from the antenna device 1 according to the reference example described above in that it is fixed with an adhesive or the like. The circuit auxiliary board 11 is a thin circuit board in which a wiring pattern (not shown) is formed on one side of an insulating thin board made of a liquid crystal polymer material or the like having a good high frequency characteristic to form a component mounting surface 11a. Since various chip components 12 are mounted on the component mounting surface 11a to form a detection circuit, the high-frequency circuit provided on the lower surface of the dielectric substrate 2 does not include the detection circuit. The circuit auxiliary board 11 has a larger diameter than the radiation conductor 4 and completely covers the radiation conductor 4. Furthermore, in the present embodiment, an opening 4a is formed in the substantially central portion of the radiation conductor 4, and a concave step portion 2a that protrudes from the opening 4a is formed on the upper surface of the dielectric substrate 2, as shown in FIG. A space in the recessed step portion 2a is a storage space for the chip component 12 group. The wiring pattern 3 of the high-frequency circuit and the detection circuit on the circuit auxiliary substrate 11 side are connected to each other by a conductive pin 13 penetrating the dielectric substrate 2. Although not shown, a radiation conductor is connected to a terminal portion of the detection circuit. 4 feeding points are soldered.

Thus, in addition to the effects of the antenna device 1 according to the reference example described above , the antenna device 10 according to the present embodiment example can disperse the built-in high-frequency circuit between the dielectric substrate 2 and the circuit auxiliary substrate 11. Therefore , the entire apparatus can be reduced in size, and the radiation auxiliary conductor 4 can be covered and protected by the circuit auxiliary board 11 so that the reliability is improved. In addition, an opening 4a is formed in a substantially central portion of the radiation conductor 4 that hardly contributes to the generation of an electric field, and the opening 4a and the recessed step portion 2a of the dielectric substrate 2 are used to provide a storage space for the chip component 12 group. Therefore, the overall thickness of the device provided with the circuit auxiliary board 11 is reduced without adversely affecting the antenna characteristics.

In the antenna device provided with the circuit auxiliary board 11 as in the present embodiment, a circuit other than the detection circuit or a part thereof may be provided on the circuit auxiliary board 11.

It is sectional drawing of the antenna apparatus which concerns on a reference example . It is explanatory drawing which shows the attachment structure of the crystal oscillator incorporated in this antenna apparatus. It is explanatory drawing which shows the state which installed this antenna apparatus in the tire. It is sectional drawing of the antenna device which concerns on the example of embodiment of this invention. FIG. 3 is a plan view showing the antenna device with a circuit auxiliary board omitted. It is sectional drawing of the antenna device which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Antenna apparatus 2 Dielectric board | substrate 2a Concave step part 3 Wiring pattern 4 Radiation conductor 4a Opening 5 Electronic component 5a Crystal oscillator 5e Crystal piece 6 Feeding pin 7 Grounding conductor plate 7a Concave lid part 7b Eave part 7c Vent hole 8 Ventilation Waterproof member 11 Circuit auxiliary board 11a Component mounting surface 12 Chip component 13 Conductive pin 20 Tire 21 Wheel 22 Valve

Claims (7)

A dielectric substrate having a wiring pattern formed on one side and a radiation conductor formed on the other side, an electronic component mounted on the one side of the dielectric substrate and constituting a high-frequency circuit together with the wiring pattern, and the dielectric A power feeding means for electrically connecting a power feeding point of the radiation conductor and the wiring pattern through the substrate, and a grounding conductor plate attached to the one side of the dielectric substrate in a state of covering the electronic component; A circuit auxiliary board having a diameter larger than the radiation conductor and a component mounting surface on which one side is mounted with a chip component ;
The grounding conductor plate is provided with a concave lid portion having a storage space for the electronic component, the periphery of the concave lid portion is closely fixed to the one surface of the dielectric substrate , and the circuit auxiliary substrate Is fixed on the other surface of the dielectric substrate with the component mounting surface facing the radiation conductor .   2. The ventilation / waterproofing according to claim 1, wherein a ventilation hole is formed in the grounding conductor plate or the dielectric substrate so as to communicate the space in the concave lid portion and the external space, and the ventilation hole has a breathability and a waterproof property. An antenna device characterized by being blocked by a member.   3. The antenna device according to claim 2, wherein the ventilation hole is formed in the concave lid portion of the ground conductor plate, and the ventilation waterproof member is adhered to an outer surface of the concave lid portion.   4. A flat flange that surrounds the entire periphery of the open end of the concave lid portion on the ground conductor plate according to any one of claims 1 to 3, and the flange is connected to the dielectric. An antenna device, wherein the antenna device is in close contact with the one surface of the substrate.   5. The antenna device according to claim 1, wherein a crystal resonator is included in the electronic component. 2. The detection circuit according to claim 1 , wherein a detection circuit is provided on the component mounting surface of the circuit auxiliary board, and a feeding point of the radiation conductor and the wiring pattern are electrically connected via the detection circuit. An antenna device characterized by that. 7. The method according to claim 1 , wherein an opening is formed in a substantially central portion of the radiation conductor, and a concave step that protrudes from the opening is formed in the other surface of the dielectric substrate. An antenna device characterized in that a space becomes a storage space for the chip parts.

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