Patent Publication Number: US-2007103850-A1

Title: Cage type battery terminal

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
      This application claims priority to U.S. Provisional Patent Application No. 60/721,133, filed on Sep. 28, 2005, to inventors Dawn Melman and Robert Miller of Illinois, U.S.A., the contents of that application being incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      Electronic key fobs may be used for remote keyless entry systems in vehicles. Early electronic key fobs operated using infrared. More recent models use challenge-response authentication over radio frequency, and thus are harder to copy and do not need line of sight to operate as opposed to some of their ancestral infrared key fobs.  
      Remote keyless entry key fobs are increasingly becoming popular for use by drivers to unlock and sometimes even open the doors/trunks of their vehicle without inserting a key into the door/trunk. Modem remote keyless access key fobs permit a user to depress a button, etc. to activate the key fob. Upon activation of a remote keyless entry key fob by a user, the key fob emits a radio signal, this radio signal being received by a receiver in the user&#39;s vehicle. The receiver analyzes the signal and determines whether the signal is indicative of a recognized signal to command an onboard keyless entry system to unlock doors/open doors/open trunks, etc.  
      Key fobs are increasingly used in apartment buildings and condominium buildings for access to common areas (i.e. lobby doors, storage areas, fitness room, pools, etc.). Some may be programmed to allow access only to those areas in which the tenant or owner is permitted to access, or only within certain time frames, etc.  
      Telecommuters may also use an electronic device known as a key fob that provides one part of a three way match to log in over an unsecure network connection to a secure network. This kind of key fob may have a keypad on which the user must enter a PIN to retrieve an access code, or it could be a display-only device such as a VPN token that algorithmically generates security codes as part of a challenge/response authentication system.  
      Key fobs typically require a battery and include a circuit board. Typically the battery and the circuit board are enclosed in a housing of the key fob. Key fobs are typically carried in the user&#39;s pocket, purse, etc., and are often subject to jostling, shaking, vibration and shock. Further, key fobs are typically also connected to keys, especially ignition keys, and thus often hang from the ignition key while the ignition key is in the ignition switch while the user is driving his/her car. During driving, the key fob will move back and forth as the vehicle experiences acceleration and deceleration (due to change in forward velocity, bumps, change in direction, etc.), and also experience vibration. These movements/shocks/vibrations induce movement between the battery (usually a button cell battery) powering the key fob and battery connectors of the key fob. Moreover, these phenomena sometimes induce flexing of the housing of the key fob which may create an opening in the electrical circuit of which the battery is part (i.e., a space opens between battery terminals/pads and terminals of the battery). Even when no space is opened, fretting corrosion may occur, which may be induced by the movement/shocks/vibrations of the key fob. Fretting corrosion may lead to poor reliability with respect to powering the key fob. In some key fobs, connector grease is utilized to address these problems. However this has been found undesirable in many instances.  
     SUMMARY OF THE INVENTION  
      In a first embodiment of the invention, there is a key fob, comprising a plastic housing; a circuit board; and a battery cage attached directly to the circuit board and directly on a surface of the circuit board, wherein the circuit board assembly includes a battery pad on the circuit board, the battery cage includes a battery terminal, and the circuit board with the battery cage attached directly to the circuit board and directly on the surface of the circuit board is housed in the housing in such a manner that the housing does not contact the battery cage.  
      In another embodiment of the invention, there is a device as described above or below, where at least one button configured to be depressed by a user and to at least one of close and open a circuit, the circuit being at least in part contained on the circuit board thereby generating a radio signal. In another embodiment of the invention, there is a device as described above or below, which includes a circuit board; and a battery cage attached directly to the circuit board and directly on a surface of the circuit board, wherein the circuit board assembly includes a negative battery pad on the circuit board, and the battery cage includes a positive battery terminal.  
      In another embodiment of the invention, there is a device as described above or below, the battery cage includes a battery dock configured to receive a battery of cylindrical configuration, the battery dock comprising a first arm; a second arm opposite the first arm with respect to the battery dock; and a third arm. In another embodiment of the invention, there is a device as described above or below, where the first and second arms form lateral sides of the battery dock, and wherein the third arm forms a longitudinal side of the battery dock, wherein lateral and longitudinal directions are the same as the respective directions of the battery of cylindrical configuration when docked in the dock. In another embodiment of the invention, there is a device as described above or below, where the circuit board forms another longitudinal side of the battery dock opposite the third arm. In another embodiment of the invention, there is a device as described above or below, where the first arm, the second arm, the third arm and the circuit board are configured to cooperate to trap a button cell battery in the battery dock.  
      In another embodiment of the invention, there is a device as described above or below, where at least the first arm and the third arm are configured to elastically deform to receive the button cell battery and trap the button cell battery in the battery dock. In another embodiment of the invention, there is a device as described above or below, where the third arm includes a positive battery terminal which is in electrical communication with components on the printed circuit board. In another embodiment of the invention, there is a device as described above or below, where the circuit board assembly is configured to complete a circuit between the negative battery pad and the positive battery terminal of the battery cage when the button cell battery is trapped in the battery dock. In another embodiment of the invention, there is a device as described above or below, where the negative battery pad on the circuit board is integral with the circuit board. In another embodiment of the invention, there is a device as described above or below, where the circuit board is a printed circuit board.  
      In another embodiment of the invention, there is a device as described above or below, where the battery cage is at least one of directly soldered to the circuit board, directly bolted to the circuit board, and directly riveted to the circuit board.  
      In another embodiment of the invention, there is a device as described above or below, where the battery cage comprises a single piece of conductive material.  
      In another embodiment of the invention, there is a device as described above or below, where the battery cage comprises a single piece of conductive metal, the metal being plastically deformed to be in the form of the battery cage, the metal further being configured to elastically deform to receive a button cell battery and trap the button cell battery between the battery cage and the circuit board.  
      In another embodiment of the invention, there is a device as described above or below, including a button cell battery including a positive terminal and a negative terminal, the negative terminal being in direct contact with and directly on the circuit board. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of necessary fee.  
       FIG. 1  is an isometric schematic of a key fob according to an embodiment of the present invention.  
       FIG. 2  is a cross-sectional view of the key fob presented in  FIG. 1 .  
       FIG. 3  is an isometric schematic of a circuit board assembly utilized in a key fob according to an embodiment of the present invention.  
       FIG. 4-9  present various views of a plurality of embodiments of a battery cage utilized in some embodiments of the present invention.  
       FIGS. 10-11  present two views of a battery cage attached to a circuit board according to an embodiment of the present invention.  
       FIG. 12  presents a circuit diagram of a circuit board utilized in an embodiment of the present invention.  
       FIG. 13  presents a schematic of a printed circuit board utilized in an embodiment of the present invention.  
       FIG. 14  presents a schematic of a vehicle assembly including a key fob according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF SOME EMBODIMENTS  
      In a first exemplary embodiment of the present invention, as may be seen in  FIG. 1 , there is a remote keyless entry key fob  100 . Key fob  100  includes a chain  102  with a key ring (not shown) configured to connect to car keys. The key fob  100  may include buttons  104  and  106 , which may be utilized to activate the key fob  100  to send a signal to a vehicle to unlock a car door (button  104 ), or send a signal to a vehicle to open a trunk (button  106 ). The key fob  100  may include additional buttons or fewer buttons, and may include no buttons at all (instead utilizing heat sensors, etc.).  
       FIG. 2  depicts an exaggerated and modified cross-sectional view of the key fob  100  depicted in  FIG. 1 . As may be seen, the key fob  100  includes a key fob housing  120  which protects a circuit board assembly  200  which is supported by support pedestals  130 . In an exemplary embodiment of the key fob  100 , the housing  120  is formed from, hard plastic, and the support pedestals  130  may be integrally formed with the housing  120  during an injection molding operation or the like. In some embodiments, the housing  120  is formed in two parts, the parts being held together by latch assemblies  140 , the components of which may be integrally formed with the housing  120 , just as may be the case with the pedestals  130 .  
      In some embodiments of the present invention, the circuit board assembly  200  includes a circuit board  210  and a battery cage  220  attached directly to the circuit board  210  and directly on the top surface  230  of the circuit board  210 . The battery cage  220  is configured to provide a battery dock  240  for a button cell battery  1000  (although in other embodiment, other cage designs may be utilized for other types of batteries) and secure/trap the button cell battery  1000  in the battery dock  240 , as may be seen in  FIG. 3 , where the battery  1000  is presented in dashed line format.  
      As may be seen, an embodiment of the present invention includes a cage type positive battery terminal that is utilized in conjunction with a negative battery pad on a printed circuit board. Specifically, in some embodiments, the battery cage  220  includes a positive battery terminal  250  configured to form an electrical contact with the battery  1000  secured in the battery dock  240 . The battery cage  220  is further in electrical contact with circuitry on the circuit board  210 , thus permitting current to flow between the positive terminal of the battery  1000  and the circuit board  210 , through the positive terminal  250  of the battery cage  220 .  
      The circuit board assembly  200  may also include a negative battery pad  260  on the circuit board  210 . This negative battery pad  260  is also configured to form an electrical contact with the battery  1000 . However, the negative battery pad  260  is configured to permit current to flow between the negative terminal of the battery  1000  and the circuit board  210 , through the negative battery pad  260 . Accordingly, in some embodiments, the circuit board assembly is configured to complete a circuit between the negative battery pad  260  and the positive battery terminal  250  when the button cell battery is trapped in the battery dock (discussed in greater detail below). In some embodiments of the present invention, the negative terminal pad  260  is in the circuit board  210  and directly on the surface  230  of the circuit board  210 . In some embodiments, the negative terminal pad  260  is in the circuit board  210  and forms part of the surface  230 , and is thus integral with the circuit board. It is noted that in other embodiments of the invention, the battery may be reversed, such that the pad is a positive pad and the cage contains the negative battery terminal.  
      Some of the embodiments relating to the battery dock  240  will now be described.  
      As may be seen in  FIGS. 2-3  and as detailed above, the battery cage  220  includes a battery dock  240  configured to receive a battery of cylindrical configuration (battery  1000 ). As is depicted in  FIGS. 4-6 , the battery cage  220  includes a first arm  270 , a second arm  272  opposite the first arm  270  with respect to the battery dock  240 , and a third arm  274 . In this embodiment of the invention, the first and second arms  270 / 272  form lateral sides of the battery dock  240 , and the third arm  274  forms a longitudinal side of the battery dock. Here, the lateral and longitudinal directions are the same as the respective directions of a battery of cylindrical configuration when docked in the battery dock  240 . That is, with reference to  FIG. 3 , the lateral sides of the battery dock  240  are the sides that “face” the cylindrical surface(s) of the battery  1000  (i.e., the curved surface of the battery  1000 ), and the longitudinal sides of the battery dock  240  are the sides that “face” the flat surfaces (ends) of the battery  1000  (i.e., the top and bottom of the battery where the battery terminals are located/the surfaces of the battery that are essentially normal to the axis of the cylinder). When the battery cage  220  is attached to a circuit board  210 , as may be seen in  FIG. 3  for example, the circuit board  210  forms another longitudinal side of the battery dock opposite the third arm  274 .  
      The arms  270 / 272 / 274  and the circuit board  210  are configured to cooperate together to trap/secure the button cell battery in the battery dock  240 . By way of example only and not by way of limitation, the material of the battery cage  210  may be of a spring-type material (i.e., it elastically deforms over an expected range of deformations sufficient for use). In some embodiments, at least one of the first and second arms  270 / 272  and the third arm  274  are configured to elastically deform to receive the button cell battery  1000  and trap the button cell battery  1000  in the battery dock  240 . In such embodiments, as the button cell battery  1000  is pushed into the battery dock  240  from the outside (in an exemplary embodiment, the battery cell  1000  is slid along the surface  230  of the circuit board  210 ), the increasing diameter of the battery cell  1000  (from the perspective of the tips of the arms  270 / 272 ) forces one or both of the arms  270 / 272  away from the other at least until the battery cell  1000  may be fully inserted into the dock  240 . As the diameter of the battery cell  1000  decreases (from the perspective of the tips of the arms  270 / 272 ), the battery cell  1000  becomes trapped in the dock  240 . The third arm  274  elastically deflects upwards as the battery is being inserted into the dock  240 , thus providing a compressive force onto the battery cell  1000  in the longitudinal direction. This enhances electrical contact between the circuit board assembly  200  and the battery  1000 .  
       FIGS. 7-9  depict an alternate design of the battery cage  220 .  
      In some embodiments of the present invention, the battery cage  220  design is such that it minimizes and/or eliminates micro movement of the terminal(s) in relation to the battery  1000 . This may reduce/eliminate fretting corrosion, at least at the battery-terminal interface(s). The cage design may be configured to maintain a constant, low contact resistance electrical connection between the circuit of the circuit board assembly  200  and the battery  1000 . This will reduce the occurrence of/prevent intermittent or even sustained loss of power to the circuit board. Such a configuration provides ease of battery insertion and ease of batter replacement, in that the battery  1000  may simply be slid in (and out) of the battery dock  240 .  
      As may be seen in  FIG. 2 , embodiments of the present invention include designs where the battery terminal(s) are decoupled from the housing  120  of the key fob  100 . That is, in contrast to other key fobs, the battery cage  220  only structurally contacts the circuit board  210  (and, of course, the battery  1000  when inserted in the dock  240 ). Indeed, in the embodiments depicted in the FIGS., the battery cage  220  is part of the circuit board assembly  200 . By decoupling the battery terminals from the housing  120  of the key fob  100 , movement between the battery terminals and the battery  1000  is reduced/eliminated because the flexing of the housing  120  is effectively not transferred to the battery terminal, and thus the connection is not disturbed/is less likely to be disturbed via flexing of the housing  120  that results during normal usage/exposure to the normal environment of the key fob  1000 .  
      Embodiments of the present invention permit low cost manufacture of the battery terminal/circuit board assembly. In this regard, the present invention provides ease of manufacture/assembly of the terminal  220  onto the circuit board  210 . In some embodiments of the present invention, the cage  220  may be attached to the circuit board  210  and reflow soldered with the rest of the electronic components on the circuit board. That is, some embodiments do not require a separate process to solder or otherwise attach the cage  220  to the circuit board  210 —the cage  220  may be attached to the circuit board during the process of reflow soldering other components to the circuit board. It is noted that while some embodiments of the invention utilize direct soldering of the cage  220  to the circuit board  210 , other embodiments utilize direct bolting, direct riveting, etc., of the cage  220  to the circuit board  210 .  
      In some embodiments of the invention, the battery cage self-centers during the process of attaching the cage  220  to the circuit board  210 . In this regard, in some embodiments of the invention, the cage  220  includes holes  700  (see  FIGS. 4 and 7 ) that are in pads of the cage  220 . During attachment of the cage  220  to the circuit board  210 , solder from a solder pads on the circuit board may flow through the holes  700 , which may allow the cage to self-center on the solder pads of the circuit board  210  even though the cage was not originally centered exactly on the solder pads.  
       FIGS. 10 and 11  depict battery cages  220  soldered to the circuit board  210 , with element  201  being a bead of solder.  
      The battery cage may be manufactured from a single piece of conductive material, such as metal. In an exemplary embodiment, a flat pattern for the cage  220  is cut out or otherwise formed in a piece of flat, relatively thin material, and the material is then plastically deformed to be in the form of the battery cage  220 . In this regard,  FIG. 4  presents a view of the cage  220  from which this concept may be readily extrapolated in view of, for example, known metal stamping/bending technologies.  
      Embodiments of the present invention utilizing the designs depicted in the figures and variations thereof typically provide advantages over through-hole battery terminal designs in that through-hole battery terminal designs interfere with components on the other side of a circuit board (this is especially the case with respect to a printed circuit board). In contrast, utilizing the surface mount design as taught herein eliminates possible interference with components on the other side of the circuit board, at least with respect to a double sided circuit board.  
       FIG. 12  depicts a wiring diagram of a circuit  300  that may be utilized in the circuit board  210  of the present invention. The circuit  300  depicted in  FIG. 12  is a circuit for a remote keyless entry key fob with multiple functions (e.g., unlock, car start, panic, auxiliary functions, etc.)  FIG. 13  depicts a schematic of a printed circuit board according to an embodiment of the present invention. In this regard, it is noted that printed circuit boards may be used for the circuit board  210  described herein.  
       FIG. 14  depicts an embodiment of the present invention that includes a vehicle assembly comprising a vehicle  400  and a key fob  100 . In this embodiment, the key fob includes a key chain  102  which is attached to a key  500  that is configured to be inserted into an ignition  600  of the car vehicle and activate an engine  700  of the car vehicle when the key  500  is turned to activate the ignition.  
      Given the disclosure of the present invention, one versed in the art would appreciate that there are other embodiments and modifications within the scope and spirit of the present invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention.