Patent Application
20080055184
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, an exemplary embodiment of the invention will be described in detail with reference to the drawings.
An antenna device 10 according to an exemplary embodiment of the invention will be described with reference to
The antenna device 10 includes a dome-shaped top cover 11, a bottom plate 12, an antenna module 13 disposed in the top cover 11, a packing member 14, a signal line 15, and a permanent magnet 16. The top cover 11 and the bottom plate 12 are assembled by four screws 17 and thus constitute an antenna case.
The packing member 14 is formed of, for example, resin materials such as silicon rubber and EPDM rubber (ethylene propylene rubber).
The packing member 14 is disposed at the joint portion between the top cover 11 and the bottom cover 12 to ensure sealing of the antenna case. Since the packing member 14 has a waterproof function, the packing member 14 is called as a waterproof packing. The signal line 15 is connected to the antenna module 13. The packing member 14 will be described below in more detail.
The antenna module 13 includes an antenna plate 131, an antenna probe 132, a dielectric spacer 133, a ground plate 134, a circuit board 135, and a shield case 136.
The ground plate 134 is made of metal and has a substantially rectangular shape. The antenna plate 131 is made of metal and has a substantially rectangular shape. The antenna plate 131 serves as a metal-plate loop antenna element. The antenna plate 131 is opposed to the ground plate 134 at a predetermined distance, with a dielectric spacer 133 interposed therebetween. The dielectric spacer 133 is made of ABS resin and has a substantially rectangular shape.
The antenna plate 131 has a pair of screw penetration holes 131a in a pair of corner portions opposed to a first diagonal. The dielectric spacer 133 has a pair of screw penetration holes 133a in positions corresponding to the pair of screw penetration holes 131a. Two screws 137 are coupled with the pair of screw penetration holes 131a of the antenna plate 131 and the pair of screw penetration holes 133a of the dielectric spacer 133 to fix the antenna plate 131 and the dielectric spacer 133 to each other.
The ground plate 134 has a pair of screw penetration holes 134a in a pair of corner portions opposed to a second diagonal extending in a direction across the first diagonal. The dielectric spacer 133 has a pair of screw penetration holes 133b in positions corresponding to the pair of screw penetration holes 134a. Two screws 138 are coupled with the pair of screw penetration holes 134a of the ground plate 134 and the pair of screw penetration holes 133b of the dielectric spacer 133 to fix the ground plate 134 and the dielectric spacer 133 to each other.
As described above, the antenna plate 131, the dielectric spacer 133, and the ground plate 134 are fixed to one another by the four screws 137 and 138 to be handled as a single part. Accordingly, the four screws 137 and 138 serve as a fixing member for fixing the antenna plate 131, the dielectric spacer 133, and the ground plate 134. The antenna probe 132 is integrated with the antenna plate 131. The antenna plate 131, the antenna probe 132, the dielectric spacer 133, and the ground plate 134 constitute an antenna element. That is, since the antenna element can be handled as a single part, the antenna module 13 or the antenna device 10 can be easily assembled.
Each area of the surfaces of the ground plate 134 and the antenna plate 131 is smaller than that of the above-described Patent Document 1. When the ground plate and the antenna plate become small in size, the electrostatic capacity of the antenna element may decrease. Accordingly, the antenna device may not have sufficient gain. However, in the antenna device 10 of the invention, since the dielectric spacer 133 is interposed between the ground plate 134 and the antenna plate 131, relative permittivity between the ground plate 134 and the antenna plate 131 increases to secure sufficient electrostatic capacity. For the reason, the antenna device 10 of the invention has high gain. Specifically, the dielectric spacer 133 between the ground plate 134 and the antenna plate 131 has the substantially same size as the areas opposed to the ground plate 134 and the antenna plate 131. That is, most of the space between the ground plate 134 and the antenna plate 131 is filled with the dielectric spacer 133 made of resin materials. Since the resin has higher relative permittivity higher than air does, the antenna element has sufficient electrostatic capacity.
The antenna probe 132 is integrated with the antenna plate 131. The antenna probe 132 has a substantially rectangular shape and extends substantially perpendicular to the surface of the antenna plate 131. The antenna probe 132 is shaped by punching the antenna plate 131 connected thereto. The antenna probe 132 is left as an integral part of the antenna plate 131 connected thereto. The shown antenna probe 132 is bent from the edge (one side) of the antenna plate 131 toward the center thereof. For the reason, the width between the bent portion (base of the probe) 132a and the opposite edge (side) 131c of the antenna plate 131 is large enough. As a result, even when the antenna probe 132 is bent, the bent portion of the antenna plate 131 is not deformed.
The dielectric spacer 133 has a probe penetration hole 133c through which the antenna probe 132 passes. The ground plate 134 has an opening hole 134b through which the antenna probe 132 loosely passes. In addition, a double-sided adhesive tape 139 also has an opening hole 139a through which the antenna probe 132 loosely passes. The antenna probe 132 passes through the probe penetration hole 133c of the dielectric spacer 133, the opening hole 134b of the ground plate 134, and the opening hole 139a of the double-sided adhesive tape 139. A front end portion 132b of the antenna probe 132 is electrically connected to a circuit board 135.
The antenna element receives the SDARS signal sent from the SDARS satellite. A circuit (hereinafter, referred to as processing circuit) performing various signal processes such as signal amplification for the SDARS received by the antenna element is formed on a back surface 135b of the circuit board 135. The antenna element (ground plate 134) and the surface 135a of the circuit board 135 are attached to each other by the double-sided adhesive tape 139.
The circuit board 135 is connected to a signal line 15 for drawing the SDARS signal out of the antenna case (top cover 11 and bottom plate 12). A shield case 136 for shielding the processing circuit is attached to the back surface of the circuit board 135 by soldering. The signal line 15 is drawn out through a notch portion (described below) form in the top cover 11.
In a state where the antenna module 13 and the packing member 14 are housed in the internal space of the top cover 11, the top cover 11 and the bottom plate 12 are fixed by the four screws 17, thereby integrating the antenna device 10.
The packing member 14 is made of, for example, resin materials such as silicon rubber and EPDM rubber. The packing member 14 includes a base portion 141 covering the whole antenna module 13, a gasket portion (bush portion) 142 covering the outer circumference of the signal line 15 in the notched portion (described below) formed in the top cover 11, and a frame portion 143 formed in the outer circumference of the base portion 141. Since the packing member 14 is monolithically constituted by the base portion 141, the gasket portion (bush portion) 142, and the frame portion 143, the number of parts and the number of working processes become smaller than the number of parts and the number of working processes in a case where each portion is individual part. Accordingly, the packing member 14 is useful for decrease in size, decrease in weight, reliability, and low cost.
Meanwhile, a single concave portion 12a is formed in the center portion of the bottom plate 12. A permanent magnet 16 is disposed in the concave portion 12a. The permanent magnet 16 is disposed so that the antenna device 10 is attached and fixed to the roof of the automobile. Though not shown, a resin sheet for preventing the roof of the automobile from being damaged is attached to the outward main surface of the bottom plate 12 throughout the substantially whole main surface. A model number, a name, or the like of the antenna device 10 is printed on the resin sheet.
Next, the configuration of the top cover 11 will be described with reference to
In the bottom plate 12, four screw penetration holes 12b through which the four screws 17 passes are formed at portions corresponding to the four screw bosses 115.
In the antenna device 10 with such a configuration, a waterproof structure is employed. That is, in the waterproof structure of the antenna device 10, the four screws 17 are coupled with the four screw bosses 115 of the top cover 11 through the four screw penetration holes of the bottom plate 12, and thus the top cover 11 is coupled with the bottom plate 12 by screws, with the packing member 14 interposed therebetween. Accordingly, the frame portion 143 of the packing member 14 is pressed by the waterproof rib 113 of the top cover 11 with the screw coupling pressure, thereby functioning the waterproof. In the protruding portion of the signal line is, the gasket portion (bush portion) 142 of the packing member 14 is fitted into the gasket accommodating portion 114 of the top cover 11 to make the waterproof.
The exemplary embodiment according to the invention was described above, but the invention is not limited to the above-described exemplary embodiment. For example, in the above-described exemplary embodiment, the plurality of screws are used as the fixing member for fixing the antenna plate, the ground plate, and the dielectric spacer, but the fixing member is not limited to the screws. In addition, the antenna device described in the exemplary embodiment is suitable for the SDARS-signal receiving antenna device, but is not limited thereto. That is, the antenna according to the exemplary embodiment may be employed as the GPS-signal receiving antenna device, the mobile communicating antenna device for receiving the satellite or terrestrial wave, or the like.
The entire disclosure of Japanese Patent Application No 2006-237597, filed on Sep. 1, 2006 is expressly incorporated by reference herein.
While this invention has been described in conjunction with the specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, exemplary embodiments of the invention as set forth herein are intended to be illustrative, not limiting. There are changes that may be made without departing from the sprit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2006-237597 | Sep 2006 | JP | national |
