Abstract:
A base member is adapted to be mounted on a vehicle body. A proximal end of a rod-shaped antenna body is pivotably provided on the base member. The antenna body includes an antenna element. A first conductive member is disposed in the base member and provided with a first bracket-shaped portion having elasticity. A second conductive member is electrically connected to the antenna element and provided with a second bracket-shaped portion. The second conductive member is pivotably fitted with the first conductive member while opposite outer faces of the second bracket-shaped portion is brought into elastic contact with opposing inner faces of the first bracket-shaped portion.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an antenna device adapted to be mounted on a vehicle body and in which an antenna body is pivotably provided.  
         [0002]      FIG. 5  shows an example of this kind of antenna device which is disclosed in Japanese Patent Publication No. 2003-32015A.  
         [0003]     A single plate-shaped first feeder plate  14  which is electrically connected to the proximal end of an antenna element  12  is disposed in a proximal end portion of a pivotable antenna body  10 . The first feeder plate  14  is conductive and elastic. A single plate-shaped second feeder plate  18  is disposed in a base member  16 . The second feeder plate  18  is conductive. A terminal portion  18   a  projecting from the second feeder plate  18  is electrically connected in a proper manner to a circuit board  20  which is provided in the base member  16 .  
         [0004]     A shaft  22  is made to penetrate through the first and second feeder plates  14  and  18  in a state that they are opposed to each other, whereby the first feeder plate  14  is pivotable with respect to the second feeder plate  18 . A coiled spring  24  is inserted to the shaft  22  so that the first feeder plate  14  is kept in elastic contact with the second feeder plate  18 . The elastic contact faces of the first and second feeder plates  14  and  18  are formed with a recess and a projection, respectively, that can be rendered in a fitting relationship and thereby constitute a click mechanism.  
         [0005]     In the above structure, electrical conduction is established between the proximal end of the antenna element  12  and the circuit board  20  via the first and second feeder plates  14  and  18 . Since the recess and projection of the first and second feeder plates  14  and  18  are rendered in a fitting relationship or separated from each other, the antenna body  10  can be pivoted with respect to the base member  16  and fixedly held by the latter in a prescribed posture.  
         [0006]     However, the coiled spring  24  is necessary for keeping the first and second feeder plates  14  and  18  in elastic contact with each other and the number of parts is increased accordingly. In addition, assembling work needs to be performed in a state that the coiled spring  24  is compressed and the work is complicated. Further, since elastic contact and electric conduction between the first and second feeder plates  14  and  18  are established by the single pair of faces, the stability of electrical connection is not always satisfactory.  
       SUMMARY OF THE INVENTION  
       [0007]     It is therefore an object of the invention to provide an antenna device for vehicle, that is small in the number of parts and provides stable electrical connection.  
         [0008]     In order to achieve the above object, according to the invention, there is provided an antenna device, comprising: 
        a base member, adapted to be mounted on a vehicle body;     a rod-shaped antenna body, a proximal end of which is pivotably provided on the base member, the antenna body including an antenna element;     a first conductive member, disposed in the base member and comprising a first bracket-shaped portion having elasticity; and     a second conductive member, electrically connected to the antenna element and comprising a second bracket-shaped portion, the second conductive member being pivotably fitted with the first conductive member while opposite outer faces of the second bracket-shaped portion is brought into elastic contact with opposing inner faces of the first bracket-shaped portion.        
 
         [0013]     With this configuration, the opposing inner faces of the first bracket-shaped portion are brought by their own elasticity, into elastic contact with the opposite outer faces of the second bracket-shaped portion which is electrically connected to the antenna element. Since no component corresponding to the coiled spring of the conventional structure is necessary, the number of components is reduced accordingly and assembling work is made easier. Further, since the first conductive member is brought into elastic contact with the second conductive member, electrical conduction is established through the two sets of faces and hence the electrical connection is made more stable.  
         [0014]     The antenna device may further comprise a shaft penetrating the first conductive member and the second conductive member, so that the second conductive member is pivotable about the shaft. In this case, the structure allowing the second conductive member to be pivoted can be made simple.  
         [0015]     One of each of the opposing inner faces of the first bracket-shaped portion and each of the opposite outer faces of the second bracket-shaped portion may be formed with a projection, and the other one may be formed with a recess adapted to be fitted with each other to constitute a click mechanism.  
         [0016]     In this case, the antenna body can be pivoted relative to the first conductive member and retained in a prescribed posture without increasing the number of component.  
         [0017]     Here, the projection and the recess may have such sizes that the projection is partly fitted into the recess.  
         [0018]     In this case, the elasticity of the first conductive member concentrates on the projections and the recesses so that the projections are brought into contact with the recesses with great elasticity. Accordingly, reliable electrical connection is established.  
         [0019]     In a case where each of the opposing inner faces of the first bracket-shaped portion may be formed with the recess and each of the opposite outer faces of the second bracket-shaped portion may be formed with the projection, each of the opposing inner faces of the first bracket portion may be formed with a groove communicating the recess with an edge of an associated one of the opposing inner faces.  
         [0020]     In this case, the projections of the second conductive member can easily be guided, by way of the grooves, to the positions where they fit into the recesses, respectively. 
     
    
     BRIEF DESCRIPTION OF THE INVENTION  
       [0021]     The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein:  
         [0022]      FIG. 1  is a section view of an antenna device according to one embodiment of the invention;  
         [0023]      FIG. 2A  is a section view taken along a line II-II in  FIG. 1 , showing a state that a pivotable antenna body in the antenna device is held in a prescribed angle;  
         [0024]      FIG. 2B  is a section view taken along a line II-II in  FIG. 1 , showing a state that the pivotable antenna body is held in another prescribed angle;  
         [0025]      FIG. 3A  is a top view of a base plate in the antenna device of  FIG. 1 ;  
         [0026]      FIG. 3B  is a side view of the base plate;  
         [0027]      FIG. 3C  is a section view taken along a line IIIC-IIIC in  FIG. 3A ;  
         [0028]      FIG. 3D  is a section view taken along a line IIID-IIID in  FIG. 3A ;  
         [0029]      FIG. 4A  is a top view of a pivot plate in the antenna device of  FIG. 1 ;  
         [0030]      FIG. 4B  is a side view of the pivot plate;  
         [0031]      FIG. 4C  is a section view taken along a line IVC-IVC in  FIG. 4A ;  
         [0032]      FIG. 5  is a section view of a conventional antenna device. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0033]     Embodiments of the invention will be described below in detail with reference to the accompanying drawings.  
         [0034]     In an antenna device according to one embodiment of the invention, the proximal end of an antenna element  30  is screwed into an insertion fitting  32  which is conductive. A bracket-shaped pivot plate  34  is fixed to the insertion fitting  32  by caulking with its opening down and electrical conduction is thereby established between them. A resin mold  36  is formed with the insertion fitting  32  and the pivot plate  34  inserted therein. Both side walls of the bracket-shaped pivot plate  34  are exposed and serve as outer walls of the resin mold  36 . Part of the resin mold  36  and the antenna element  30  are covered with a cover  38  made of an insulative resin, whereby a pivotable antenna body  40  is formed.  
         [0035]     As shown in  FIG. 4  in detail, the pivot plate  34  is formed as follows. A bracket-shaped part is formed by working on a conductive metal sheet. Holes  34   a  for shaft insertion are formed through the two respective side walls of the bracket-shaped part, and projections  34   b  project outward from the two respective side walls. A caulking hole  34   c  for fixing to the insertion fitting  32  is formed through the connecting wall of the bracket-shaped part.  
         [0036]     A base member  44  is molded out of an insulative resin with a base plate  42  inserted therein. As described in  FIG. 3  in detail, the base plate  42  is formed by working on a conductive and elastic metal sheet of stainless steel or the like so as to have a bracket-shaped cross section. Holes  42   a  for shaft insertion are formed through the two respective side walls of the bracket-shaped part, and plural (in this embodiment, three) holes  42   b  (or recesses) are formed on a circle that is centered by each of the holes  42   a.  The inner face of each of the two side walls of the bracket-shaped part is formed with a groove  42   c  that communicates with the outer periphery and one of the holes  42   b.  A terminal portion  42   d  projects from the connecting wall of the bracket-shaped part. The terminal portion  42   d  is disposed in the base member  44  so as to project properly in an accommodation place of a circuit board  46  which is provided in the base member  44  as shown in  FIG. 1 .  
         [0037]     The pivot plate  34  of the pivotable antenna body  40  is inserted into the bracket-shaped part of the base plate  42  of the base member  44 , the holes  34   a  and  42   a  for shaft insertion are registered with each other, and a shaft  48  is inserted through those holes  34   a  and  42   a.  As a result, the pivotable antenna body  40  is made pivotable with respect to the base member  44 . Further, a case  50  is placed so as to cover the base member  44 . The case  50  restricts the shaft  48  properly so that the shaft  48  does not come off. It goes without saying that the projections  34   b  of the pivot plate  34  are located at such positions as to be able to be opposed to and fitted into the pair of holes  42   b  of the base plate  42 .  
         [0038]     With the above configuration, if an attempt to pivot the pivotable antenna body  40  is made by a force that is stronger than a prescribed level, as shown in  FIG. 2B , the opening dimension of the bracket-shaped part of the base plate  42  is increased because of its elastic deformation, and the projections  34   b  of the pivot plate  34  escape from the pair of holes  42   b  of the base plate  42 . The pivotable antenna body  40  is rendered pivotable.  
         [0039]     When the projections  34   b  of the pivot plate  34  are located at such positions as to be opposed to the pair of holes  42   b  of the base plate  42 , the opening dimension of the bracket-shaped part of the base plate  42  is made small because of its own elastic deformation, whereby the projections  34   b  are inserted (fitted) in the respective holes  42   b . As shown in  FIG. 2A , the pivotable antenna body  40  is fixed (i.e., its posture is maintained) as long as a force for pivoting the pivotable antenna body  40  is weaker than the prescribed level.  
         [0040]     In this manner, the projections  34   b  and the holes  42   b  serve as a click mechanism. If the dimensions of the holes  42   b  and the projections  34   b  are set so that the projections  34   b  cannot be fully inserted into the holes  42   b  (i.e., insertion of the projections  34   b  is disabled halfway and their fitting is completed in this state), the elasticity of the base plate  42  concentrates on the fitting portions and the pivot plate  34  can be brought into contact with the base plate  42  with great elasticity. Reliable electrical connection is thereby established.  
         [0041]     Since the pivot plate  34  is attached to the base plate  42  in such a manner that the projections  34   b  reach the holes  42   b  passing through the grooves  42   c,  the pivot plate  34  can be attached without elastically deforming the opening portion of the bracket-shaped part of the base plate  42  unduly.  
         [0042]     In this embodiment, the dimensions of the holes  42   b  and the projections  34   b  are set so that the projections  34   b  cannot be fully inserted into the holes  42   b  (i.e., insertion of the projections  34   b  is disabled halfway and their fitting is completed in this state). However, the projections  34   b  may be fully inserted into the holes  42   b , in which case the two inner faces of the base plate  42  are brought into elastic contact with the respective side faces of the pivot plate  34 .  
         [0043]     In this embodiment, the pivotable structure is realized by letting the shaft  48  penetrate through the base plate  42  and the pivot plate  34 . However, screws or the like serving as shafts may be inserted from both sides. Alternatively, instead of the holes  42   a  and  34   a  for shaft insertion, the base plate  42  and the pivot plate  34  may be formed with circular recesses and projections (the latter can be fitted into the former) capable of operating equivalently to a shaft.  
         [0044]     In this embodiment, the holes  42   b  of the base plate  42  and the projections  34   b  of the pivot plate  34  constitute the click mechanism. However, the base plate  42  may be formed with projections and the pivot plate  34  may be formed with holes (or recesses). Alternatively, the click mechanism is not necessarily provided in the elastic contact faces of the base plate  42  and the pivot plate  34 . For example, a click mechanism may be realized in such a manner that balls urged by springs are provided in elastic contact with recesses formed in the resin mold  36  of the pivotable antenna body  40  so that the balls can be fitted into and separated from them. It would be understood easily that the click mechanism may have any structure. The postures in which the pivotable antenna body  40  is held by the click mechanism be set as appropriate, such as a horizontal posture and postures with elevation angles of 60 and 90 degrees.  
         [0045]     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.