Abstract:
A high reliability battery contact assembly ( 100 ) for use in an electronic device includes a battery contact block ( 103 ) comprised of a plurality of cantilevered contacts ( 105, 107, 109 ). A redundant ground contact ( 111 ) is connected to the metallic housing of the electronic device ( 101 ) and positioned adjacent to the battery contact block ( 103 ). The cantilevered contacts include a primary power contact ( 105 ), a sensing contact ( 107 ) and a ground contact ( 109 ). The battery contact assembly ( 100 ) is advantageous in that it requires a very limited amount of surface area while still working to prevent a reset condition of an electronic device that might occur due to a loss in electrical continuity during adverse conditions.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to battery contacts and, more particularly, to a battery contact assembly for maintaining circuit continuity. 
     BACKGROUND 
     Electronic portable devices typically use some form of removable battery pack for powering the device. Cantilever spring battery contacts are often used to bring power from the removable battery pack to a printed circuit (PC) board located in the device. Based on a range of design tolerances, these springs have a minimum beam length and height. Due to the nature of the springs these contacts can take up valuable PC board space. An example of this type of electronic device is a two-way radio transceiver. 
     One problem associated with battery packs of this type occurs when they are subjected to adverse conditions such as a fall or drop onto a hard surface. This subjects the battery pack and its associated electrical contacts to such high “g” loads that the impact often temporarily disconnects the battery from the electronic device. This, inturn, can cause a condition often referred to as “reset” where information stored in static memory may be lost during the time this discontinuity occurs. Moreover, in situations where these types of batteries are used in public safety applications, such as a two-way radio transceiver for police and fire personnel, the transceiver may be in an “off” state where the user is unaware of this situation and important communications could be missed. Although redundant battery contacts have been used in battery packs of the prior art, this solution often requires a great deal of physical space making the battery contact area larger than can be accepted for required design parameters. 
     Accordingly the need exists for a battery contact assembly having high reliability that requires a limited amount of surface area for preventing reset conditions of an electronic device in adverse conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
         FIG. 1  illustrates an exploded view of radio housing with battery contact block and accompanying battery in accordance with an embodiment of the invention. 
         FIG. 2  illustrates a perspective view of the battery contact block as shown in  FIG. 1 . 
         FIG. 3  illustrates a perspective view of a cantilevered contact in accordance with an embodiment of the invention. 
         FIG. 4  illustrates a perspective view of a double cantilevered contact in accordance with an embodiment of the invention. 
         FIG. 5  illustrates a perspective view of the redundant ground contact in accordance with an embodiment of the invention. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
     DETAILED DESCRIPTION 
     Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to a battery contact assembly. Accordingly, the apparatus components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
       FIG. 1  illustrates an exploded view of radio assembly  100  including a radio housing  101  with battery contact block  103  and accompanying battery housing  105  in accordance with an embodiment of the invention. The contact block  103  is exposed through an aperture in the housing  105 . The contact block  103  includes a primary power contact  105 , a sense contact  107  and a ground contact  109 . In order to provide a high degree of reliability during a drop condition of the device, a redundant ground contact  111  is provided for contacting a portion of the battery housing  105 . 
     As seen in  FIG. 1 , the redundant ground contact  111  is mechanically fastened to a metallic portion of the radio housing  101  and may be in the form of a lug or resilient terminal that projects away from the surface of the radio housing  101 . This provides a ground contact which makes a good mechanical ground with the battery housing  105  when they are both engaged in a unitary manner (not shown). The battery housing  105  includes a plurality of corresponding contacts including a primary battery contact  105 ′, a sense contact  107 ′ and a ground contact  109 ′. A screw  113  or other type of metallic fastener on the battery may be used to make contact with the redundant ground contact  111 . 
       FIG. 2  illustrates a magnified prospective view of the battery contact block  200 . The contact block  200  includes a substantially rectangular base  201  made of a hardened plastic or other non-conductive material. The contact block includes a plurality of cantilevered contacts providing resilient or spring-like action when in a compressed position. As described in  FIG. 1 , the rectangular base  201  includes a primary contact  203  which is comprised of a double cantilevered contact to provide redundancy in a high stress or drop condition of the device. A sensing contact  205  is a single cantilevered contact that works to convey operational and control information to and from the battery. This information might relate to such parameters as battery charge level, charge state and/or condition. 
     A grounding contact  207  is a single cantilevered contact used to provide a ground return path. In order to keep the overall size of the contact block  201  as small as possible, the ground contact  207  is made as only a single unitary contact with additional redundancy for the ground return available through the redundancy ground contact  111 . Those skilled in the art will recognize that the primary contact  203 , sensing contact  205  and grounding contact  207  may each be connected directly to a printed circuit board through connecting points  219 ,  211 ,  213  or may be connected using fasteners or direct wire connections. 
     Finally,  FIG. 3  illustrates a perspective view of a cantilevered contact in accordance with an embodiment of the invention. The cantilevered contact  250  is typically a flat wire material which is rigid and electrically conductive. The contact  250  includes a protruding contact portion  251  which is bent at a top edge  253  where a lower edge  255  is folded under the top edge  253 . The lower edge  255  is further bent into a flat section  257 . The contact portion  251  connects with a u-shaped fastener portion  259 . The fastener portion  253  is formed from an upper fastener  261  and a lower fastener  263 . The lower fastener  263  includes an engaging aperture  265  enabling the lower fastener  263  to engage with a locking member (not shown) located within the contact block  200  for holding the contact  250  into a fixed position.  FIG. 4  illustrates a perspective view of a double cantilevered contact  270 . The double cantilevered contact  270  is like that of  FIG. 3  except for a double protruding contact portion  271 ,  271 ′ and a wider upper fastener  273  and lower fastener  275 .  FIG. 5  illustrates the magnified perspective view of a redundant ground contact  300 . The redundant ground contact  300  is made of a substantially flat conductive material that includes a lug section  301 , tapered section  303 , contact section  305  and end section  307 . 
     Thus, the present invention is a high reliability battery contact assembly which solves the problem of providing battery power contact redundancy in a substantially small battery contact header. The contact block includes redundant power (B+) contacts, one sense contact and an additional single ground contact connected directly with the printed circuit board. A second or redundant ground contact is used which is integrated into the rear metallic casting of the electronic device. In that redundant ground contact on the casting, electronic parts can be placed directly below the redundant contact on the printed circuit (PC) board. This ultimately saves valuable PC board space while still providing contact redundancy and continuous continuity during a high stress condition such as a drop onto a hard surface. 
     In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.