Abstract:
An antenna formed of a mounting base, an antenna terminal and a transmission box is described for use in an automobile. The antenna terminal is pivotally attached to the mounting base by a ball and socket joint. The mounting base has a bearing plate supported on a spring member and forced by the spring member to adjustably positively hold down the antenna terminal in position.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to antennas and, more particularly, to an antenna for mounting on the windshield for radio communication.  
           [0003]    2. Description of the Related Art  
           [0004]    Following the fast development of communication technology, a variety of mobile communication apparatus have been disclosed and commercialized. Further, regular automobiles commonly have an antenna for receiving radio signal.  
           [0005]    [0005]FIG. 1 illustrates an antenna for use in an automobile. As illustrated, the antenna comprises an antenna terminal  5 , a mounting base  6 , and a transmission box  7 . The antenna terminal  5  is a metal member having two mounting lugs  51  arranged in parallel at one end of the terminal body  50  thereof. Each mounting lugs  51  has a pivot hole  52  transversely aligned in a line. The mounting base  6  is comprised of a holder plate  60  and a connector  61 . The holder plate  60  has a through hole  62 . The connector  61  is made from metal, having a shaft  63  inserted through the through hole  62  of the holder plate  60  and a pivot hole  64  transversely extending through the distal end of the shaft  63  and aligned between the pivot holes  52  of the mounting lugs  51  of the antenna terminal  5 . A screw bolt  53  is fastened to the pivot hole  64  of the shaft  63  and the pivot holes  52  of the mounting lugs  51  to pivotally secure the antenna terminal  5  to the holder plate  60  and the connector  61 , enabling the antenna terminal  5  to be turned about the screw bolt  53  relative to the mounting base  6 . A retainer ring  54  is mounted in one end of the terminal body  50  between the pivot holes  52  of the mounting lugs  51  around the threaded shank of the screw bolt  53  to hold the antenna terminal  5  in position and to allow the terminal body  50  to be turned about the screw bolt  53  by force. The transmission box  7  comprises a casing  70 , a cover plate. 71 , a metal plate  72 , and a transmission line  73 . The casing  70  defines a receiving open chamber  74 . The cover plate.  71  is fastened to the casing  70  to close the receiving open chamber  74 , having a center wire hole  75 . The metal plate  72  is located on one side of the cover plate  71  opposite the receiving open chamber  74 . The transmission line  73  is received in the receiving open chamber  74 , having one end inserted through the wire hole  75  and electrically connected to the metal plate  72 . During installation, the mounting base  6  is mounted on the outer surface of the windshield outside the automobile, and the transmission box  7  is mounted on the inner-surface of the windshield inside the automobile opposite the mounting base  6 , enabling signal to be transmitted between the transmission line  73  and the antenna terminal  5  through the connector  61  and the metal plate  72  via the windshield.  
           [0006]    According to the aforesaid, antenna structure, the antenna terminal is pivotally fastened to the base by a screw bolt. When the automobile moves over an uneven road surface, the antenna terminal tends to vibrate and shift to a different angular position, resulting in reception failure or poor reception. When fastening the screw bolt, a screwdriver or like tool should be used. Further, the fabrication of the transmission box is complicated because a wire hole must be made in the cover plate for passing therethrough of the transmission line and the transmission line must be fastened to the metal plate by soldering when the same extends out of the cover plate through the wire hole.  
           [0007]    for an automobile  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention has been accomplished with the above drawbacks in view. It is therefore the main object of the present invention to provide an antenna for an automobile, which antenna can easily be adjusted to the desired angle and position by hand without tools. It is another object of the present invention to provide an antenna for an automobile, the antenna terminal of which maintains a position of the antenna and free avoids vibration due to the automobile. It is still another object of the present invention to provide an antenna for an automobile, which antenna is easy and inexpensive to manufacture.  
           [0009]    According to one aspect of the present invention, the antenna comprises an antenna terminal, a mounting base and a transmission box. The antenna terminal further comprises a spherical coupling portion at one end thereof. The mounting base further comprises a holder shell, an opening, a metal block and a metal spring means. The holder shell receives the spherical coupling portion of the antenna terminal. The antenna terminal extends out of the mounting base through the opening. The metal block is fixedly fastened to a bottom side of the holder shell for adhesion to an outer surface of the windshield of an automobile. The metal spring means is supported on the metal block and stopped against the spherical coupling portion of the antenna terminal to hold the spherical coupling portion of the antenna terminal in position. The transmission box comprises a metal plate adhered to an inner surface of the windshield of the automobile in which the mounting base is installed and is disposed inside the automobile opposite the mounting base. A transmission line electrically extends from the metal plate for connection to a wireless communication system inside the automobile.  
           [0010]    According to another aspect of the present invention, the transmission box further comprises a casing and a circuit board. The casing defines a receiving open chamber, which receives the transmission line. The circuit board is mounted in the receiving open chamber of the casing and is electrically connected to the transmission line. The metal plate is built in one side of the circuit board opposite the transmission line for fastening to the inner surface of the windshield. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The drawings included herein provide a further understanding of the invention. A brief introduction of the drawings is as follows:  
         [0012]    [0012]FIG. 1 is an exploded view of an antenna for an automobile according to the prior art;  
         [0013]    [0013]FIG. 2 is an exploded view of an antenna for an automobile according to the present invention;  
         [0014]    [0014]FIG. 3 is a view of the present invention showing the antenna installed in the windshield of an automobile;  
         [0015]    [0015]FIG. 4 is a cross-sectional side view with enlarged scale of the antenna according to the present invention; and  
         [0016]    [0016]FIG. 5 is an exploded view of an alternate form of the antenna for an automobile according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Referring to FIG. 2, an antenna for an automobile in accordance with the present invention is shown and comprises an antenna terminal  1 , a mounting base  2 , and a transmission box  3 .  
         [0018]    The antenna terminal  1  comprises a tubular terminal body  11  and a connector  10 , both made from copper. The terminal body  11  has an inner thread  15  in the bottom end. The connector tip  10  comprises a spherical coupling portion  12  and a shank  13  extending from the periphery of the spherical coupling portion  12 . The shank  13  has an outer thread  14  threaded into the inner thread  15  of the terminal body  11 .  
         [0019]    The mounting base  2  comprises a holder shell  20 , a metal ball socket  25 , a metal block  22 , a spring member  23  and a metal bearing member  24 . The metal ball socket  25  is mounted in the holder shell  20  and holds the spherical coupling portion  12  of the connector  10  on the inside. The metal ball socket  25  has an opening  21  for the passing of the shank  13  of the connector  10 . The metal block  22  is fixedly fastened to the holder shell  20  on the bottom side. The spring member  23  is supported on the metal block  22 . The metal bearing member  24  supports the spherical coupling portion  12  of the connector  10  on the spring member  23 . The spring member  23  forces the bearing member  24  against the spherical coupling portion  12  of the connector  10 , holding the connector  10  and the antenna terminal  1  in position.  
         [0020]    The transmission box  3  comprises a casing  30 , a circuit board  31 , a metal plate  34 , and a transmission line  32 . The casing  30  comprises a plurality of female screw rods  35  vertically suspended in four corners inside the receiving open chamber  33  defined in the casing  30 . The circuit board  31  is supported on the female screw rods  35 , having a plurality of screw holes  36  respectively fixedly connected to the female screw rods  35  by screws  37 . The metal plate  34  built in one side of the circuit board  31  opposite the receiving open chamber  33 , and is electrically connected to the transmission line  32 .  
         [0021]    Referring to FIGS. 3 and 4, during installation, the holder shell  20  of the mounting base  2  is fastened to the outer surface of the windshield  4  outside the automobile by a double-sided adhesive tape  26 , and the metal plate  34  of the circuit board  31  is fastened to the inner surface of the windshield  4  inside the automobile by a double-sided adhesive tape  39 . When installed, signal is transmitted between the antenna terminal  1  and the transmission line  32  through the mounting base  2  and the metal plate  34  via the windshield  4 . The transmission line  32  is made in the form of a coil and extends out of the transmission box  3  to the on-board wireless communication system of the automobile, for example, GSM or CDMA.  
         [0022]    Because the spherical coupling portion  12  of the connector  10  of the antenna terminal  1  pivots within the ball socket  25  inside the holder shell  20  of the mounting base  2  and is held down by the spring member  23  and the bearing member  24 , the antenna terminal  1  does not move when the automobile travels over an uneven road surface and the user can adjust the antenna terminal  1  to the desired angle and position easily and directly by hand and without tools. Further, because the metal plate  34  is built in the circuit board  31  and the transmission line  32  is directly electrically connected to the circuit board  31 , the whole structure of the transmission box  3  is simple.  
         [0023]    [0023]FIG. 5 illustrates an alternate form of the antenna for an automobile according to the present invention. According to this alternate form, the transmission line  32 ′ has one end terminating in a terminal connector  38 , which is fixedly in the peripheral wall of the casing  30  for the connection of the cable of the wireless communication system of the automobile.  
         [0024]    A prototype of antenna for an automobile has been constructed with the features of the annexed drawings of FIGS.  2 ˜ 5 . The antenna for an automobile functions smoothly to provide all, of the features discussed earlier.  
         [0025]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications, and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.