Patent Publication Number: US-7218283-B2

Title: Motor-vehicle antenna mount

Description:
FIELD OF THE INVENTION 
   The present invention relates to an antenna mount. More particularly this invention concerns a mount for securing an antenna to a motor vehicle. 
   BACKGROUND OF THE INVENTION 
   As described in copending application Ser. No. 10/732,922 filed 10 Dec. 2003, an antenna assembly for mounting upon a wall of a vehicle body has a metallic base plate with a face adapted to be juxtaposed with the vehicle wall. A plastic housing encloses antenna elements mounted on the base plate. A seal between the plate-shaped portion and the wall seals the base plate relative to an interior of the vehicle body. A threaded mounting pin extends downward from the metallic base plate. 
   Here a cable extends through the base plate to the antenna elements, where it is normally soldered to traces of a circuit board. The circuit board in turn is formed with a plurality of holes matching threaded holes in the base plate so this circuit board can be secured in place by screws. Such mounting is fairly complex and requires quite a few parts. It therefore considerably elevates the cost of this mass-production item. 
   What is more the complex prior-art assembly often requires two people for installation. One must hold it in place atop the vehicle with its threaded mounting pin projecting down through the roof, while the other fits a washer and nut on this pin to secure it in place. This type of assembly further raises the installation costs for the device. 
   In the known devices an excessive pull on the cables extending from the circuit board down through the base plate can create problems. Since the cables are normally soldered directly to traces on the board, too much tension can rip them loose and even pull the traces off the board, ruining it beyond repair. 
   OBJECTS OF THE INVENTION 
   It is therefore an object of the present invention to provide an improved motor-vehicle antenna mount. 
   Another object is the provision of such an improved motor-vehicle antenna mount that overcomes the above-given disadvantages, in particular that is of relatively simple and inexpensive construction and that is relatively easy to install, even by one person. 
   A further object is to provide such a motor-vehicle antenna mount where the cables extending from the circuit board are solidly anchored in the assembly. 
   SUMMARY OF THE INVENTION 
   According to the invention a flat base plate sits atop a motor-vehicle panel and is formed with a mounting pin extending downward through the panel. A flat antenna circuit board sits on the base plate, and a connector cable extends upward through the pin and through the base plate and is connected to the circuit board. In accordance with the invention a one-piece mounting element is unitarily formed with an upper face and latch formations projecting from the upper face and latchingly engageable with the circuit board to retain the circuit board on the upper face. It is further unitarily formed with a lower face and latch formations projecting from the lower face through the base plate and roof panel and latchingly engageable with the roof panel to hold the circuit board and base plate down against the roof panel. 
   Thus this mounting element is clipped on one side to the circuit board and on the opposite side through the base plate to the vehicle panel, normally the roof, to secure the entire assembly together. No separate fasteners are used and, according to the invention the mounting element is plastic and the latching formations are oppositely extending sets of elastically deflectable arms having outer ends formed with barbs. The circuit board and base plate are formed with respective arrays of throughgoing holes through which the respective arms project. 
   The mounting element is formed offset from the arms with an outwardly projecting guide pin. The circuit board is formed with a throughgoing hole in which the guide pin is received when the respective latch formations are engaged with the circuit board. There is only one such guide pin and it is set to one side, so that it ensures that the mounting element will be installed in the desired orientation. 
   The mounting element is formed with a seat in which the cable is snugly engageable. This seat is so constructed that it guides the cable through a stress-relieving bend. In practice there are often two such cables and two such seats of different sizes. One or both of the seats can be formed with a cross-wise cable-gripping ridge. The mounting element thus serves as a strain relief for the cables. In fact it facilitates attachment of the cables to the antenna board, producing a subassembly that comprises the antenna board, the mounting element, and the cables that can be installed on the base plate and that can be handled, prior to installation on the base plate, without having to worry about the fragile connection of the cables to the antenna board. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
       FIG. 1  is a perspective view from above of the mounting element according to the invention; 
       FIG. 2  shows the element with connector cables in place; 
       FIG. 3  is a bottom view of the structure of  FIG. 3  mounted on a circuit board; 
       FIG. 4  is a large-scale top view of a detail of the structure of  FIG. 3 ; 
       FIG. 5  is a top view of the base plate of the mount in accordance with the invention; 
       FIG. 6  is a bottom view of the base plate; 
       FIG. 7  is a top view of the base plate with the antenna module in place; and 
       FIG. 8  is a large-scale bottom view of the structure of  FIG. 7 . 
   

   SPECIFIC DESCRIPTION 
   As seen in  FIG. 1  a plastic injection-molded mounting element  1  is a generally rectangular annular frame centrally defining a throughgoing rectangular-section opening  33 . It has on each side at the corners two normally downwardly extending legs  2  each having in turn an outwardly extending barb or tooth  3 . The element  1  has an upwardly directed planar seat surface  7  from which two legs or projections  4  extend upward and an opposite downwardly directed planar bottom surface  34  that is parallel to the top surface  7 . The projections  4  are parallel to each other on opposite sides of the central hole  33  and have oppositely and outwardly directed barbs or teeth  6 . An upwardly tapered frustoconical centering pin  6  projects upward from the surface  7  to one side of the two projections  4 . The entire element  1  is stiff but slightly elastically deformable. It is formed with two oppositely extending grooves  8  and  9  opening at the surface  7  and of different radii of curvature. One of the grooves  8  is shown to have a radially inwardly projecting cable-gripping ridge  36 . 
     FIG. 2  shows two coaxial cables  10  and  11  fed up through the hole  33 , bent through  90 E, and then laid in the grooves  8  and  9 . Each such cable  10  and  11  comprises a central core conductor  12 , an insulating sleeve  13  around, a braid conductive shield sleeve  14  around the insulation  13 , and a tubular insulating jacket  15  over the shield sleeve  14 . The right-angle bend, the snug fit in the grooves  8  and  9 , and even the ridge  36  biting into the cable  10 , ensure that these cables  10  and  11  are solidly locked in the element  1 . Thus a pull on the portion of the cable  10  or  11  hanging down from the hole  33  will be transmitted to the mounting element  1 , not to the end of the cable  10  or  11  projecting parallel to the surface  7  from the element  1 . 
     FIGS. 3 and 4  show how the element  1  with the two cables  10  and  11  is secured to the face of a planar antenna-circuit board  16 , with the upper face  7  bearing flatly on the board  16  and its lower face  34  turned downward away from the board  16 . To this end the two projections  4  extend through respective rectangular throughgoing holes  17  in the board and the barbs  5  snap out on the upper face of the board  16  and lock the element  1  to the board  16 . The centering pin  6  fits through a hole  18  in the board  16  to ensure proper orientation of the element  1  on the board  16 . The two cables  10  and  11  are compressed by the board  16  into the grooves  8  and  9  to provide excellent strain relief so that a pull on the cables  10  and  11  below the board  16  will not be transmitted through to the outer ends of the cables  10  and  11  to loosen them from the traces they are soldered or otherwise connected to. The antenna board  16 , mounting element  1 , and cables  10  and  11  together form a stable subassembly that can be handled using normal care without damaging it. 
     FIGS. 5 and 6  show a metallic base plate  19  having a planar upper seat surface  20  from which extend peripheral and crosswise rectangular-section ridges  21  intended to complementarily hold and receive the circuit board  16 . The height of the ridges  21  is equal to the thickness of the element  1  between its faces  7  and  34 . In addition this plate  19  is formed with eight holes  23  through which the legs  2  can fit and with a square central hole  22  identical to the hole  33  of the element  1 . On its lower face the plate is unitarily formed with a downwardly projecting and externally threaded mounting pin  26  having a central throughgoing hole  22 , with grooves  27  extending the holes  23  in a square downward projection  28  surrounding the pin  26  and ending in a lower flat surface  32  ( FIG. 8 ). An annular inner seal  25  and an annular outer seal  24 , both of elastically compressible plastic, are set in the bottom face of the plate  19 . An annular array of mounting holes  31  is formed in the plate  10  between the seals  24  and  25  to allow the plate  19  to be screwed, if desired, to a roof panel shown schematically at  35  in  FIG. 7 . When the plate  19  is set on a complementarily flat surface of a motor-vehicle roof, these seals  24  will provide a double barrier against leakage. 
     FIG. 7  shows how the antenna board  16  fits atop the plate  18 , resting on the ridge  21  that will make a solid ground contact with a peripheral trace on an underside of the board  16 . The upper face of the board  16  carries a GPS antenna  29  and a rod-type cell-phone antenna  30 . Normally in fact the circuit board  16  is screwed or soldered to the plate  19  so that the board  16  and antennas  29  and  30  are shielded from below and a ground trace on the board  16  makes electrical connection with the normally metallic and conductive plate  19 . Thus the subassembly of the antenna board  16 , the mounting element  1 , and the cables  10  and  11  is formed into a larger very solid subassembly including the base plate  19 . 
     FIG. 8  shows the mount according to the invention from underneath, with the roof panel  35  not shown for clarity of view. The projection  28  fits through a complementary square hole in the roof panel  35  so that the barbs  3  can engage underneath the roof panel  35  and lock the entire assembly together and to the roof. One person can therefore easily snap the subassembly comprised of the board  16 , mount  1 , cables  10  and  11 , and plate  19  into place on the roof, leaving it solidly held in place. If desired a nut and washer can be fitted over the pin  26  and screwed up against the lower face of the panel, but at least during assembly the legs  2  will hold the entire assembly together so that one person can do the installation. In addition if necessary the legs  2  can be pushed together to allow the antenna subassembly to be removed for servicing or replacement.