Vehicle antenna equipment

Abstract

Provided is a vehicular antenna device in which inadvertent force due to thermal stress is not applied to a circuit board on an antenna base and which places few restrictions on the layout of the circuit board.　This vehicular antenna device comprises an antenna base 10, an antenna case 20, an antenna element 30, and a circuit board 40. The antenna base 10 comprises a resin base 11 and a conductive base 12. The antenna element 30 has a power supply unit 31. The circuit board 40 has connected thereto the power supply unit 31 of the antenna element 30, extends over the conductive base 12 of the antenna base 10, is fixed to the conductive base 12, and further extends over the resin base 11. When the antenna base 10 is fixed to the antenna case 20, the circuit board 40 is fixed by having at least a portion of the circuit board 40 extending over the resin base 11, sandwiched between the resin base 11 and the antenna case 20.

Description

Vehicle antenna device

[0001] The present invention relates to a vehicle antenna device, and more particularly to a vehicle antenna device that is fixed to a vehicle and houses a circuit board.

[0002] Vehicle antenna devices fixed to vehicles typically include antenna elements capable of receiving AM and FM broadcasts. Small, low-profile antenna devices, known as shark fin antennas, house such antenna elements in an internal space. Recently, vehicle weight reductions have been promoted in consideration of fuel economy, as exemplified by electric vehicles and hybrid cars. Lightweight vehicle antenna devices are also required, and resin-based vehicle antennas, instead of conductive bases, are being developed. For example, Patent Document 1 discloses a composite antenna base that combines a resin base and a conductive base.

[0003] International Publication No. 2012 / 127903

[0004] A circuit board is fixed to the antenna base of a vehicle antenna device, on which a connector for connecting the antenna element's power supply and an amplifier circuit for amplifying the antenna element's received signal are mounted. When the circuit board extends from the conductive base onto the resin base and is fixed to each of the conductive base and the resin base, thermal stress can be applied to the circuit boards fixed to each of the conductive base and the resin base due to the difference in thermal expansion coefficients between the conductive base and the resin base. Such thermal stress can cause connectors on the circuit board to become misaligned, wiring to break, or the circuit board to crack. This has resulted in limitations on the layout, such as a limitation in the size of the circuit board, or the need to position the circuit board separately on the conductive base and the resin base.

[0005] Therefore, there has been a demand for the development of a vehicle antenna device that does not apply unintended force due to thermal stress to the circuit board on the antenna base and that places fewer restrictions on the layout of the circuit board.

[0006] SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a vehicle antenna device in which unintended force due to thermal stress is not applied to the circuit board on the antenna base and there are fewer restrictions on the layout of the circuit board.

[0007] In order to achieve the above-mentioned object of the present invention, the vehicle antenna device according to the present invention comprises an antenna base consisting of a resin base and a conductive base, an antenna case fixed to the antenna base and defining an internal space together with the antenna base, an antenna element arranged in the internal space of the antenna case and having a power supply portion, and a circuit board to which the power supply portion of the antenna element is connected, extending above the conductive base of the antenna base and fixed to the conductive base, and extending up to above the resin base, and when the antenna base is fixed to the antenna case, at least a portion of the circuit board extending above the resin base is sandwiched between the resin base and the antenna case, thereby fixing the circuit board.

[0008] Furthermore, the antenna base may be provided with a connection terminal mounted on a circuit board extending over the resin base of the antenna base and to which the power supply portion of the antenna element is connected.

[0009] Here, the antenna case may have a shark fin shape, and the connection terminal may be placed on the circuit board in the internal space near the short tip of the shark fin shape of the antenna case.

[0010] The antenna may further include an amplifier circuit mounted on a circuit board extending over the conductive base of the antenna base.

[0011] The antenna element may also be fixed to the antenna case.

[0012] In addition, the power supply portion of the antenna element may be made of a plate-like terminal having a plate-like flat portion, the surface direction of the flat portion of the plate-like terminal being oriented in the axial direction passing from the low front end to the rear end of the shark fin shape, and the connection terminal may be made of a leaf spring terminal that clamps the surface of the flat portion of the plate-like terminal.

[0013] Furthermore, the antenna may be provided with a waterproof pad interposed between the antenna base and the antenna case to waterproof the internal space, and at a position where at least a part of the circuit board is sandwiched between the resin base and the antenna case, a part of the waterproof pad may also be interposed between the resin base and the circuit board and / or between the antenna case and the circuit board.

[0014] The vehicle antenna device of the present invention has the advantages that no unintended force due to thermal stress is applied to the circuit board on the antenna base, and there are few restrictions on the layout of the circuit board.

[0015] Fig. 1 is a schematic exploded perspective view illustrating the vehicle antenna device of the present invention. Fig. 2 is a schematic enlarged side cross-sectional view illustrating details of a fixing portion of a circuit board of the vehicle antenna device of the present invention. Fig. 3 is a schematic enlarged perspective view illustrating details of a power feed portion and a connection terminal of an antenna element of the vehicle antenna device of the present invention. Fig. 4 is a schematic enlarged perspective view illustrating details of a waterproof pad of the vehicle antenna device of the present invention. Fig. 5 is a schematic enlarged side cross-sectional view of a waterproof pad corresponding to Fig. 4 of the vehicle antenna device of the present invention. Fig. 6 is a schematic enlarged side cross-sectional view illustrating details of another waterproof pad of the vehicle antenna device of the present invention.

[0016] The following describes an embodiment of the present invention with reference to the accompanying drawings. The vehicle antenna device of the present invention has an antenna element covered by a housing fixed to a vehicle. An example in which the present invention is applied to a low-profile roof-mounted antenna device will be specifically described below. As long as the antenna element covered by a housing is fixed to the vehicle, the fixing position is not limited to roof-mounted antenna devices, and may be, for example, a dashboard antenna device.

[0017] 1 is a schematic exploded perspective view illustrating a vehicle antenna device of the present invention. As shown in the figure, the vehicle antenna device of the present invention is mainly composed of an antenna base 10, an antenna case 20, an antenna element 30, and a circuit board 40. Note that the shapes of the components shown in the figure are merely examples and are disclosed for the purpose of explanation, and the vehicle antenna device of the present invention is not limited to these shapes.

[0018] The antenna base 10 is made up of a resin base 11 and a conductive base 12. It is a so-called composite antenna base. The antenna base 10 shown in the figure has a through-hole near the center of the resin base 11, and the conductive base 12 is configured to fit into the through-hole. The resin base 11 fits into an opening of an antenna case 20 (described below) so as to cover the opening. The resin base 11 and the antenna case 20 may be fixed together by, for example, screws 23. The conductive base 12 serves as the ground for a circuit board 40 (described below). More specifically, the conductive base 12 has, for example, a screw boss that is inserted into a through-hole in the vehicle roof and fixed with a nut or the like, thereby providing electrical continuity with the vehicle roof.

[0019] The antenna case 20 is fixed to the antenna base 10 and defines an internal space together with the antenna base 10. The internal space of the antenna case 20 houses an antenna element 30 and a circuit board 40, which will be described later. The antenna case 20 shown in the figure has a so-called shark fin shape. However, the present invention is not limited to this, and any shape having an internal space, such as a triangular or rectangular shape, may be used. The antenna case 20 may also have a double cover using an inner cover and an outer cover.

[0020] The antenna element 30 is disposed in the internal space of the antenna case 20. The antenna element 30 may be, for example, a radio antenna element. The antenna element 30 shown in the figure is an umbrella-shaped element, which is a so-called top-loaded antenna element. However, the present invention is not limited to this, and any shape that functions as an antenna element, such as a flat or meandered shape, may be used. The antenna element 30 also has a power feed portion 31. In the illustrated example, the power feed portion 31 is disposed at the low front end of the antenna case 20. However, the present invention is not limited to this, and the power feed portion 31 may be disposed at the center or rear end of the antenna element 30.

[0021] The circuit board 40 is connected to the power supply portion 31 of the antenna element 30. The circuit board 40 extends over the conductive base 12 of the antenna base 10, is fixed to the conductive base 12, and extends onto the resin base 11. That is, the circuit board 40 extends from the conductive base 12 to the resin base 11. The circuit board 40 is fixed to the conductive base 12, for example, by screws 13. The ground of the circuit board 40 is electrically connected to the conductive base 12, for example, via the screws 13, so that the vehicle roof serves as ground. On the other hand, as described below, the circuit board 40 is not fixed to the resin base 11 by the screws 13. That is, when the antenna base 10 is fixed to the antenna case 20, at least a portion of the circuit board 40 extending over the resin base 11 is sandwiched between the resin base 11 and the antenna case 20, thereby fixing the circuit board 40.

[0022] A more detailed description will be given below with reference to FIG. 2 . FIG. 2 is a schematic enlarged side cross-sectional view illustrating the details of the fixing portion of the circuit board of the vehicle antenna device of the present invention. In the figure, parts with the same reference numerals as in FIG. 1 represent the same components. As shown, the antenna case 20 is fixed to the antenna base 10, for example, with screws 23. At this time, the circuit board 40 extending on the resin base 11 is sandwiched and fixed between the fixing protrusions 15 provided on the resin base 11 and the fixing ribs 25 provided on the antenna case 20. That is, the circuit board 40 is fixed by sandwiching the front and back surfaces of the circuit board 40 between the fixing protrusions 15 and the fixing ribs 25 on the resin base 11. Because the front and back surfaces of the circuit board 40 are sandwiched between the fixing protrusions 15 and the fixing ribs 25 on the resin base 11, the circuit board 40 is fixed so as to be slidable in the horizontal direction. On the other hand, the circuit board on the conductive base 12 is fixed to the conductive base 12 with the screws 13 and therefore does not move in the horizontal direction. In this way, the circuit board 40 is fixed to the conductive base 12, but is slidably fixed on the resin base 11. Therefore, even if the resin base 11 and the conductive base 12 have different thermal expansion coefficients and the resin base 11 or the conductive base 12 expands or contracts in the horizontal direction due to thermal changes, an inadvertent force due to thermal stress is not applied to the circuit board 40. It is more effective to fix the circuit board 40 on the resin base 11 at a position that allows it to slide in the longitudinal direction, which is more affected by the expansion and contraction of the resin base 11 and the conductive base 12.

[0023] In the illustrated example described above, the circuit board 40 is sandwiched between the fixing protrusions 15 and the fixing ribs 25, but the present invention is not limited to this. The circuit board 40 may be sandwiched between the protrusions, for example, as long as it is sandwiched and fixed between the antenna base 10 and the antenna case 20. Furthermore, the method of fixing the antenna base 10 and the antenna case 20 is not limited to using the screws 23, and may be fixed using engaging claws or the like.

[0024] The antenna element 30 may also be fixed to the antenna base using a support member or the like. The power supply portion 31 of the antenna element 30 may be directly connected to the circuit board 40. Furthermore, the antenna element 30 may also be fixed to the antenna case 20. As shown in Fig. 2, a connection terminal 41 to which the power supply portion 31 of the antenna element 30 is connected may be mounted on the circuit board 40.

[0025] As described above, in the prior art, the circuit board had to be mounted and fixed only on the conductive base to prevent inadvertent force due to thermal stress from being applied to the circuit board. Therefore, even if a connection terminal was desired to be placed near the short end of the antenna case, it was not possible to do so because the circuit board was not present. However, in the vehicle antenna device of the present invention, the circuit board 40 is not subjected to inadvertent force due to thermal stress, so the circuit board can be extended to any desired position. Therefore, for example, if the antenna case 20 has a shark fin shape, the circuit board 40 can be extended to near the short end of the shark fin shape. This allows the connection terminal 41 to be placed on the circuit board 40 in the internal space near the short end of the shark fin shape. In this way, there are fewer limitations on the layout of the circuit board 40.

[0026] An amplifier circuit 42 may also be mounted on the circuit board 40. Because the amplifier circuit 42 requires a ground, it is preferable that it be mounted on the circuit board 40 that extends above the conductive base 12. Because the ground of the circuit board 40 is electrically connected to the conductive base 12, it is preferable that the amplifier circuit 42 be mounted in a position close to the conductive base 12. In this case, the connection terminal 41 is disposed near the short tip of the shark fin shape, and the amplifier circuit 42 is disposed on the circuit board 40 that extends above the conductive base 12 in the portion covered by the antenna element 30.

[0027] Next, details of the power feed portion and connection terminal of the antenna element of the vehicle antenna device of the present invention will be described using FIG. 3 . FIG. 3 is a schematic enlarged perspective view for explaining the details of the power feed portion and connection terminal of the antenna element of the vehicle antenna device of the present invention. In the figure, parts with the same reference numerals as in FIG. 1 represent the same components. Also, only the power feed portion 31 and the connection terminal 41 and their surroundings are shown, and other components are omitted. The power feed portion 31 of the antenna element 30 may be, for example, a plate terminal having a flat, plate-like portion. In this case, as shown in the figure, the surface direction of the flat portion of the plate terminal may be configured to face the axial direction passing through the low front end and rear end of the shark fin shape. The connection terminal 41 may be a leaf spring terminal that clamps the surface of the flat portion of the plate terminal. In other words, the clamping groove of the connection terminal 41 also faces the axial direction passing through the low front end and rear end of the shark fin shape. The plate-shaped terminal of the power supply portion 31 is sandwiched between the connection terminals 41, which are leaf spring terminals, so as to be slidable in the longitudinal direction of the antenna base 10.

[0028] 3, by configuring the power supply portion 31 and the connection terminal 41 to be slidable in the longitudinal direction of the antenna base 10, even if the resin base 11 and the conductive base 12 expand and contract in the longitudinal direction, which is more affected by thermal changes, and the position of the circuit board 40 shifts relative to the antenna element 30 fixed to the antenna case 20, it is possible to prevent poor contact due to inadvertent application of force caused by thermal stress. In other words, inadvertent force caused by thermal stress of the antenna base 10 is not applied between the power supply portion 31 and the connection terminal 41. Meanwhile, as described above, the circuit board 40 on the resin base 11 is sandwiched between the fixing protrusions 15 and the fixing ribs 25, and is therefore stably fixed at least in the vertical direction, so that it does not slide vertically between the power supply portion 31 and the connection terminal 41.

[0029] Furthermore, the vehicle antenna device of the present invention may have a waterproof pad 50, as shown in Fig. 2. The waterproof pad 50 is interposed between the antenna base 10 and the antenna case 20 to waterproof the internal space and the space between the vehicle roof and the antenna base 10. The waterproof pad 50 is configured to cover, for example, the lower part (vehicle roof side) of the antenna base 10 and extend from the side to the contact part with the antenna case 20. In other words, the waterproof pad 50 may be configured to cover the antenna base 10.

[0030] A portion of this waterproof pad 50 may be configured to be interposed between the resin base 11 and the circuit board 40. FIG. 4 is a schematic enlarged perspective view illustrating the details of the waterproof pad of the vehicle antenna device of the present invention. FIG. 5 is a schematic enlarged side cross-sectional view of the waterproof pad of the vehicle antenna device of the present invention, corresponding to FIG. 4. In the figure, parts with the same reference numerals as in FIG. 2 represent the same objects. Also, only the fixing protrusions 15 and the fixing ribs 25 and their surroundings are shown, and other parts are omitted. As shown, a portion of the waterproof pad 50 is configured as a spacer portion 51 processed to cover the protrusions of the fixing protrusions 15. That is, the spacer portion 51 of the waterproof pad 50 is configured to be interposed between the fixing protrusions 15 of the resin base 11 and the circuit board 40 at a position where the circuit board 40 is sandwiched between the fixing protrusions 15 of the resin base 11 and the fixing ribs 25 of the antenna case 20. With this configuration, even if there is a design error in the gap when the circuit board 40 is sandwiched between the fixing protrusion 15 and the fixing rib 25, the error can be absorbed by the spacer portion 51.

[0031] FIG. 6 is a schematic enlarged side cross-sectional view illustrating the details of another waterproof pad for a vehicle antenna device according to the present invention. In the figure, parts with the same reference numerals as those in FIG. 2 represent the same components. Also, only the periphery of the fixing protrusion 15 and the fixing rib 25 is shown, and other parts are omitted. As shown in the figure, in this example, the spacer portion 52 of the waterproof pad 50 is configured to be interposed between the fixing rib 25 of the antenna case 20 and the circuit board 40 at a position where the circuit board 40 is sandwiched between the fixing protrusion 15 of the resin base 11 and the fixing rib 25 of the antenna case 20. The spacer portion 52 may be configured to extend, for example, from the side edge of the circuit board 40 to the upper surface. For example, after the circuit board 40 is fixed to the antenna base 10, the waterproof pad 50 is placed over the antenna base 10. At this time, the spacer portion 52 is configured to be positioned at a position on the upper surface of the circuit board 40 sandwiched between the fixing protrusion 15 and the fixing rib 25. Even with this configuration, even if there is a design error in the gap when the circuit board 40 is sandwiched between the fixing protrusions 15 and the fixing ribs 25, the error can be absorbed by the spacer portions 52. Note that the spacer portion 51 shown in Fig. 5 and the spacer portion 52 shown in Fig. 6 may be combined. In other words, a configuration may be adopted in which a part of the waterproof pad 50 is interposed between the resin base 11 and the circuit board 40, and between the antenna case 20 and the circuit board 40.

[0032] The vehicle antenna device of the present invention is not limited to the above-described illustrated example, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0033] REFERENCE SIGNS LIST 10 Antenna base 11 Resin base 12 Conductive base 13 Screw 15 Fixing protrusion 20 Antenna case 23 Screw 25 Fixing rib 30 Antenna element 31 Power supply part 40 Circuit board 41 Connection terminal 42 Amplifier circuit 50 Waterproof pad 51 Spacer part 52 Spacer part

Claims

DEPCT691. Vehicle antenna device to be mounted to the vehicle housing, the vehicle antenna device comprises: an antenna base with a resin base and a leaded base; an antenna box mounted to the antenna base and defining its internal space together with the antenna base; an antenna component placed in the internal space of the antenna box and having a feed section; and a circuit board to which the feed section of the antenna component is connected, where the circuit board protrudes above the leaded base while mounted and further protrudes above the resin base, where, when the antenna base is mounted to the antenna box, at least part of the circuit board protruding above the resin base is sandwiched between the resin base and the antenna box to secure the circuit board.

2. Vehicle antenna device according to claim 1, which comprises a connection connector placed on the part of the circuit board protruding above the resin base of the antenna base and to which the feed section of the antenna component is connected.3.The vehicle antenna device under claim 2, where the antenna housing is shaped like a shark fin, and the connection connector is mounted on a portion of the circuit board within the empty space adjacent to the lead end which is made on the lower height side of the shark fin shape.

4. The vehicle antenna device under claim 3, which subsequently incorporates the amplifier circuit mounted on a portion of the circuit board protruding above the lead end of the antenna base.

5. The vehicle antenna device under claim 4, where the antenna element is secured to the antenna housing.

6. The vehicle antenna device under claim 5, where the feed portion of the antenna element is constructed with a plate-type connector with a flat plate section and the surface direction of the flat plate section of the connector is oriented in an axial direction passing from the lead end on the lower height side of the shark fin shape to its rear end, and the connection connector is constructed with a plate-type spring connector shaped to maintain contact with the surface of the flat plate section of the connector. 7.Vehicle antenna equipment as provided by any of Claims 1 through 6, which subsequently includes: a waterproof plate placed centrally between the antenna base and the antenna box to ensure waterproofing within the internal space, where the waterproof plate is placed centrally either between the resin base and the circuit board and / or between the antenna box and the circuit board at a position where at least part of the circuit board is sandwiched between the resin base and the antenna box;