Abstract:
A connector is provided for use in a battery pack for connecting the battery cells to the telephone and to a battery charger. The connector utilizes stamped nickel contact pads which may be spot welded directly to the battery cells. The use of the stamped nickel contact pads results in improvements in strength of the connector and a reduction in the cost as compared to the prior art flexible circuit board-type connectors.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method of connecting a battery circuit in a cellular telephone and more particularly to an electrical connection for telephone and charge connection in a battery pack. 
     2. Description of the Related Art 
     Battery packs for use with cellular telephones or the like normally employ a plurality of battery cells generally comprised of nickel metal hydride material. The battery cells are positioned in a battery pack housing and are electrically connected together. Previous electrical connectors or connections have been provided for connecting the battery cells in the battery pack to the telephone and to a battery charger. One old method of providing the connection was to utilize a flexible circuit board to connect the spring rails to the connector as well as the thermistor. The batteries were connected to the flexible circuit board by a spot weld joint between a nickel ribbon and a bare copper pad. The flexible circuit board is soldered to the spring rails with the thermistor being soldered to the flexible circuit board. The prior art method described hereinabove results in a more costly construction and the flexible circuit board does not normally have the necessary strength for connection between the battery cells and the spring rails of the connection. 
     SUMMARY OF THE INVENTION 
     An electrical connection is described for connecting the battery cells in a battery pack in a suitable manner for enabling the battery cells to be connected to the telephone and to a battery charger. The battery pack comprises an elongated hollow housing having a plurality of battery cells positioned therein. A contact assembly or connection is positioned in the housing and comprises an elongated, substantially flat, electrically conductive, positive contact leg which is spaced from a substantially flat, electrically conductive, negative contact leg. The negative and positive contact legs are positioned substantially parallel with respect to one another in a spaced-apart relationship. An elongated, electrically conductive tab member has one end thereof electrically connected to the negative contact leg and extends therefrom towards the positive contact leg. A thermistor has one lead electrically connected to the tab member and a second lead electrically connected to the positive contact lead. An electrically conductive, first contact pad is electrically connected to the positive contact leg and extends therefrom towards the negative contact leg. An electrically conductive second contact pad is electrically connected to the negative contact leg and extends therefrom towards the positive contact leg. The first and second contact pads are comprised of a nickel material. The contact pads are bent so that end portions thereof will be positioned in a plane transverse to the longitudinal axis of the contact legs. The end portions of the contact pads are soldered to a pair of the battery cells. The ends of the first and second contact legs have contact portions protruding therefrom. A cover is secured to the housing to close the same and had four spaced-apart openings formed therein which receive the contact portions of the positive contact leg and the negative contact leg. When the battery pack is installed in a cellular telephone or the like, the contact portions provide an electrical connection for telephone and charge connection. 
     It is therefore a principal object of the invention to provide an improved electrical connection for use in a battery pack. 
     Still another object of the invention is to provide an electrical connection for use in a battery pack which enables the battery cells to be connected to the telephone or the battery charger. 
     Still another object of the invention is to provide an electrical connector of the type described which utilizes stamped nickel pads to connect the spring rails and thermistor thereof. 
     Still another object of the invention is to provide an electrical connector of the type described which results in a reduction of cost in fabricating the battery pack in to which the connector is installed. 
     Still another object of the invention is to provide an electrical connector of the type described hereinabove which results in a more sturdy connector. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the battery pack; 
     FIG. 2 is a top view of the battery pack with portions thereof cut away to more fully illustrate the invention; 
     FIG. 3 is a partial side view of the battery pack with portions thereof cut away to more fully illustrate the invention; 
     FIG. 4 is a perspective view of the contact assembly of this invention; and 
     FIG. 5 is an exploded perspective view of the battery pack and contact assembly of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The numeral  10  refers to a battery pack housing which includes a wall  12 , side walls  14  and  16 , and end walls  18  and  20 . In some situations, an elongated piece of rubber tape  24  is placed in the housing prior to any batteries being installed therein with the rubber tape serving as a cushioning device which also prevents the battery cells from rattling within the housing  10 . A plurality of battery cells  26 , usually five in number, are placed in the housing  10  and are electrically connected together in conventional fashion. 
     The numeral  28  refers to the electrical connector of this invention which is positioned over a pair of the batteries, as illustrated in FIG.  2 . Connector  28  includes an elongated, substantially flat, positive contact leg  30  having contact portions  32  and  34  adjacent the opposite ends thereof. Contact leg  30  is also provided with a plurality of conventional plastic stand-off posts  36  which extend from the leg  30 . Connector  28  also includes an elongated, substantially flat, electrically conductive, negative contact leg  38  having contact portions  40  and  42  provided thereon adjacent the opposite ends thereof. Contact leg  38  also includes a plurality of plastic stand-off posts  43  protruding therefrom in conventional fashion. 
     An electrically conductive, substantially flat, tab member  44  has one end soldered to negative contact leg  38  and extends therefrom towards contact leg  30 , as illustrated in the drawings. The numeral  46  refers to a conventional thermistor having one lead  48  soldered to the end of tab member  44  and a lead  50  soldered to positive contact leg  30 . Preferably, contact legs  30  and  38  are comprised of a BeCu material. 
     The numeral  52  refers to a contact having one end  54  soldered to positive contact leg  30 , as illustrated in the drawings, and which has a contact portion  56  extending inwardly from the solder connection and an end portion  58  which extends therefrom, as illustrated in the drawings. Contact  52  includes an elongated slot  60  formed therein adjacent the end thereof. 
     Similarly, the numeral  62  refers to a contact having one end  64  soldered to contact leg  38  and which includes a portion  66  extending inwardly from the solder connection and an end portion  68  which has an elongated slot  70  formed therein. Preferably, the contact legs  30  and  38  are comprised of stamped nickel pads. Prior to insertion into the housing  10 , the end portions  58  and  68  are bent downwardly so that the end portions  58  and  68  are disposed substantially transversely to the longitudinal axes of legs  30  and  38 . FIG. 4 illustrates that the contact portions  34  and  42  have a V-shape while it can be seen that the contact portions  32  and  40  have a somewhat flat configuration which dwell in a plane above the longitudinal axes of the contact legs. 
     The battery cells  26  are normally glued into the housing  10  in conventional fashion. The connector  28  is then positioned over a pair of the batteries, as illustrated in FIG. 2, with the end portions  58  and  68  being spot welded to the ends of a pair of the battery cells. The connector  28  is normally secured to the battery cells prior to the battery cells being installed into the housing  10 . 
     A cover  72  is then secured to the housing  10  in conventional fashion by sonic welding or the like to close the housing  10 . Cover  72  includes openings  74  and  76  which receive the contact portions  34  and  42  of contact legs  30  and  38 , respectively. Cover  72  is also provided with a pair of openings  76  and  78  formed therein which receive the contact portions  32  and  40  of legs  30  and  38 , respectively. 
     Thus, when the battery pack is installed on the telephone or a battery charger, the contact portions on both the contact legs  30  and  38  will be exposed, providing an electrical connection for the telephone and the battery charger. 
     The utilization of stamped nickel contacts rather than a copper flexible circuit board enables the stamped parts to be soldered directly to the contact rails for phone interface. Thermistor  46  is also soldered to the stampings for charge control. The fact that the contacts  52  and  62  are comprised of a nickel material enables them to be spot welded directly to the cell pack. Preferably, the contacts  52  and  62  have selectively plated areas of TNPB to improve the solderability to the contact legs  30  and  38 . The instant invention eliminates the tabs between the old flexible circuit board and the battery cell pack. The connector of this invention improves the mechanical properties and strength of the circuit, which has been proven in destructive testing. The elimination of copper surface contamination problems found in the prior art improves welding and soldering. The reduction in cost of the connector of this invention results in a cost reduction of approximately forty percent over the prior art connector. 
     Thus it can be seen that the invention accomplishes at least all of its stated objectives.