Abstract:
A device comprises a housing including an internal chamber and an external keypad mounting area and a primary printed circuit board mounted within the internal chamber along with a secondary printed circuit board mounted on the external keypad mounting area and electrically coupled to the primary printed circuit board in combination with a plurality of switches corresponding to the keys of the key pad over the secondary printed circuit board and a key pad including a plurality of keys mounted in a predetermined alignment over the plurality of switches so that the secondary printed circuit board is between the key pad and a surface of the external key pad mounting area and the switches are between the secondary printed circuit board and the key pad.

Description:
BACKGROUND  
       [0001]     Users of mobile electronic devices often carry them throughout the day, while handling food and drinks, etc. Such use makes these devices more susceptible to damage from, for example, spills which penetrate housing openings adjacent to the keypad, etc. The housing openings also make the device susceptible to environmental contaminants, such as dust, moisture, etc.  
         [0002]     As shown in  FIGS. 1 and 2 , a housing  2  of a conventional mobile device  1  includes a keypad  12  operating switches  16  which typically reside on a main printed circuit board (“PCB”)  20  located within the housing  2  of the device  1 . An actuator or pin  10  of each of the keys  8  of the keypad  12  penetrates a keypad supporting surface  15  of the housing  2  through a separate opening  6  to reach a corresponding switch  16  on the PCB  20 . The actuators  10  are moved up and down into and out of engagement with the corresponding switches  16  as the keys are depressed. However, accommodating the movement of the actuators  10  through the holes  6  makes it difficult to maintain an adequate seal around each of the holes  6  which may lead to structural and/or electrical damage to the mobile device  1 .  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention is directed to a device comprising a housing including an internal chamber and an external keypad mounting area and a primary printed circuit board comprising expensive circuitry and components mounted within the internal chamber in combination with a secondary, simple and inexpensive printed circuit board mounted in the external keypad mounting area, the secondary printed circuit board being electrically coupled to the primary printed circuit board and a plurality of switches corresponding to the keys of the key pad over the secondary printed circuit board and a key pad including a plurality of keys mounted in a predetermined alignment over the plurality of switches so that the secondary printed circuit board is between the key pad and a surface of the external key pad mounting area and the switches are between the second printed circuit board and the key pad. Those of skill in the art will understand that the present invention reduces the chance that the primary, expensive printed circuit board will be damaged. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  shows a conventional mobile device housing and keypad support;  
         [0005]      FIG. 2  shows a conventional keypad assembly architecture;  
         [0006]      FIG. 3  shows a mobile device according to the present invention;  
         [0007]      FIG. 4  shows an exemplary embodiment of a keypad arrangement according to the present invention;  
         [0008]      FIG. 5   a  shows a front view of an external printed circuit board according to the present invention;  
         [0009]      FIG. 5   b  shows a rear view of the external printed circuit board of  FIG. 5   a;    
         [0010]      FIG. 6  shows an exemplary embodiment of an integration of a mobile device housing, including the keypad arrangement, and a main printed circuit board according to the present invention;  
         [0011]      FIG. 7  shows a side view of the mobile device shown in  FIG. 6 ; and  
         [0012]      FIG. 8  shows an exemplary embodiment of a method according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention will be described with reference to mobile electronic devices (e.g., PDA&#39;s, palm sized personal computers, cellular telephones, global positioning systems (GPS), bar code scanners, digital imagers, radio frequency identification (RFID) devices, etc.). However, those skilled in the art will understand that the integrations according to the present invention are equally suited for any electronic device utilizing a keypad or other plurality of buttons, such as, for example, mobile and stationary electronic devices including telephones, printers, copy machines, etc.  
         [0014]      FIG. 3  shows a mobile device  38  according to the present invention including a housing  30 . As would be understood by those skilled in the art, the housing  30  may be made from any suitable material(s) such as aluminum, silicon, polymer, etc., and may be formed by, for example, blow molding, injection molding, etc. Outer walls of the housing  30  define an internal chamber  31 , shown in  FIG. 6 , in which internal components (e.g., a primary PCB  60 , a battery, etc.) of the device  38  are enclosed. As would be understood by those skilled in the art, components are included within the chamber  31  for protection from environmental conditions external to the housing  30 .  
         [0015]     The housing  30  according to this embodiment includes a first opening  32  which, in this case, is a cutout sized and shaped to present for access or observation by a user an active surface of a display  33  (e.g., a passive display or touchscreen) while the balance of the display  33  is received within the chamber  31  of the housing  30 . An entire perimeter of this opening  32  is sealed in a conventional manner to protect the components within the chamber  31  of the housing  30  from any liquid or other potentially harmful substance with which the display  33  may come into contact. The housing  30  further includes a keypad receiving cavity  35  formed by a keypad supporting surface  34  and surrounding side walls  37 . However, it will be understood by those of skill in the art that the keypad of the present invention may be positioned on any surface of the housing  30 , whether or not a cavity such as the cavity  35  is included. Those skilled in the art will understand that the cavity  35  is preferably sized and shaped to accommodate a keypad arrangement  50  which includes, for example, an external circuit board  40 , a keypad  52  comprising a plurality of keys  53  coupled to a flexible sheet  54 , and a frame  56 , as shown in  FIG. 4 . As would be further understood by those skilled in the art, this exemplary keypad arrangement  50  may be replaced by any structure supporting a plurality of buttons adjacent to one another. Furthermore, as would be understood by those skilled in the art, the keypad supporting surface  34  may be formed in any conventional manner integrally with the rest of the housing  30  or as a separate element which is later joined to the housing  30 .  
         [0016]     The housing  30  includes a second opening  36  extending through the keypad supporting surface  34  allowing electrical communication between components in the keypad receiving cavity  35  and the primary PCB  60  which is located within the housing  30 , as shown in  FIG. 7 . In this manner, an electrical connection through the second opening  36  is sealed, allowing the cavity  35  to be sealed more easily and making the seal more rugged. Preferably, the second opening  36  is defined in the keypad supporting surface  34  of the cavity, although it may alternatively be defined in a side wall  37  of the cavity  35  or in any other suitable surface of the housing  30 . In the mobile device  38  according to this embodiment of the invention, each key  53  of the keypad arrangement  50  is positioned over a corresponding switch  42  on a secondary external circuit board  40  which is located within the keypad receiving cavity on the same side of the keypad supporting surface  34  as the keypad  52 . Alternatively, as would be understood by those skilled in the art, the secondary external circuit board  40  may include a number of switches  42  less than the number of keys  53  with a combination of switches activated at any given time indicating which key  53  has been actuated.  
         [0017]      FIG. 4  shows an embodiment of a system according to the present invention. The keypad supporting surface  34  includes the second opening  36 , which defines an entry site into the housing  30 . The secondary external circuit board  40  is placed over the keypad supporting surface  34 , so that a data connector  44  aligns with the second opening  36 . According to an embodiment of the present invention, the secondary external circuit board  40  may be secured to the keypad supporting surface  34  using adhesive.  
         [0018]     The keypad  52  is placed over the secondary external circuit board  40  so that a plurality of keys  53  thereof, which may be depressed by a user to enter input to the mobile device, are in a desired alignment with the switches  42 . In one embodiment of the present invention, the keys  53  are mechanically coupled to a flexible sheet (e.g., the keypad film  54 ) which may be composed of any of a number of materials, including but not limited to rubber, plastic, which can flex without breakage or fatigue when a key  53  is pressed. Accordingly, openings in the keypad film  54  are preferably minimized or, if possible, eliminated to protect the secondary external circuit board  40  from foreign substances with which the keypad  52  may come in contact. In one embodiment of the present invention, the keys  53  are coupled to the keypad film  54  by an adhesive, male/female mating, etc. According to another embodiment, the keys  53  are formed integrally with the keypad film  54 .  
         [0019]     As further shown in  FIG. 4 , an optional frame  56  which is placed over the keypad  52  includes a number of holes  57  selected to accommodate the keys  53  of the keypad  52 . The frame  56  stabilizes the keypad  52  and further protects the secondary external circuit board  40  from spills, etc. As would be understood by those skilled in the art, the frame  56  may be formed from any of a variety of materials, including plastic, metal, etc. In one embodiment of the present invention, the frame  56  is secured to the housing  30  via one or more screws (not shown). For example, in this embodiment, a plurality of screws are placed around a perimeter of the frame  56 , passing through the keypad  52  and the secondary external circuit board  40  and into the housing  30 . An overlay  58 , including holes  59 , is then placed over the frame  56  to conceal the screws. In another embodiment of the present invention, other coupling devices may be used in lieu of or in addition to the screws to secure the frame  56  to the housing  30 . For example, one or more tabs extending from the housing  30  may be flexed over the frame  56 , or the frame  56  may be bonded to the housing  30  using adhesive.  
         [0020]     As shown in  FIG. 5   b,  the secondary external circuit board  40  includes the data connector  44  (e.g., a multi-pin connector) or other electrical connection including multiple data lines. The second opening  36  is preferably sized and shaped to accommodate the data connector  44  or a cable extending therefrom so that the data connector  44  or cable may be electrically connected to corresponding contacts on the primary PCB  60  or to contacts on a component coupled thereto so that electrical signals corresponding to the actuation of the keys  53  may be transferred to the primary PCB  60 .  
         [0021]     In one embodiment of the present invention, the connector  44  is a pin and socket connector including a plurality of data pins  46 . However, it will be understood by those of skill in the art that any of a variety of connectors may be used. As shown, the connector  44  is sized to fit comfortably within the second opening  36  with a surface of the secondary external circuit board  40  lying flush against the keypad supporting surface  34  of the housing  30 . In one exemplary embodiment, an adhesive membrane may seal the secondary external circuit board  40  to the housing  30 . Thus, the port  36  is completely enclosed, and the possibility for liquid or other substances to pass therethrough is minimized.  
         [0022]     Thus, the keypad supporting surface  34  contains only a single opening (second opening  36 ) to accommodate all of the electrical connections between a plurality of keys  53  and the primary PCB  60  and a seal  48  extends around the entire perimeter of the second opening  36  so that any liquid spilled on the keypad arrangement  50  is prevented from passing through the keypad supporting surface  34 . This seal  48  is more effective than the seals in the conventional keypads as there is no relative movement between the seal  48  and the components passing through the second opening  36 . The second opening  36  may be any size and shape, although it is preferable for the second opening  36  to be as small as possible while accommodating the desired connection arrangement. For example, according to an embodiment of the present invention, the second opening  36  is approximately 50 mm 2 . The second opening  36  according to this embodiment is substantially rectangular as this facilitates manufacturing the housing  30  and sealing the second opening  36 . Specifically, the second opening  36  is preferably lined with a sealant (e.g., latex, urethane, silicone, fibrin, etc.) to prevent any substance from passing therethrough.  
         [0023]      FIG. 5   a  shows a front view of the secondary external circuit board  40  which preferably handles only those functions necessary to transfer data between the keypad  52  and the primary PCB  60 . Thus, if liquid spilled on the keypad  52  penetrates past the keypad film  54 , the secondary external circuit board  40  may be shorted out. However, the liquid will be prevented from passing across past the keypad supporting surface  34  to the primary PCB  60 . Thus, spills will be prevented from damaging the major components of the device  28  and, if liquid does pass through the keypad film  54  shorting out the secondary external circuit board  40 , the device  28  may be repaired by simply replacing this component. According to the present invention, the secondary external circuit board  40  is separate and distinct from the primary PCB  60  while electrically coupled thereto. The secondary external circuit board  40  may reside on an outer surface of the housing  30 , such as on the keypad supporting surface  34 . As described above, a plurality of switches  42  are formed on the secondary external circuit board  40  to operate in conjunction with keys.  
         [0024]      FIG. 6  shows an embodiment where the keypad assembly, integrated onto an upper portion of the housing  30 , is conjoined with the primary PCB  60 . The keypad assembly may, for example, be pieced together as discussed above with respect to  FIG. 5 . Circuitry  62  associated with the primary PCB  60  includes, for example, a connector which complements the connector  44  of the secondary external circuit board  40  so that this connector may be mated with the connector  44  to electrically couple the secondary external circuit board  40  to the primary PCB  60 . A lower portion of the housing  30  may then be joined with the upper portion and secured (e.g., with screws  66 ) to seal the chamber  31 .  
         [0025]      FIG. 7  further exemplifies an integration of the keypad arrangement  50  into a mobile device according to an embodiment of the present invention. As shown, the primary PCB  60  lies within the housing  30  with the secondary external circuit board  40  resting on an outside of the keypad supporting surface  34  which, in this embodiment, is inset with respect to an outer surface of the housing  30 . The connector  44  extends through the second opening  36  and is electrically coupled to the main PCB  60  and the keypad  52  resides over the secondary external circuit board  40 . The frame  56  and overlay  58 , respectively, reside over the keypad  52 . As shown, the keys  53  may extend past the frame  56  and the overlay  58 , allowing the size of the keypad  52  to be increased to facilitate depression of the desired keys  53 .  
         [0026]      FIG. 8  shows an exemplary method  80  for manufacturing a keypad assembly according to an embodiment of the present invention. In step  82 , a housing  30  is provided which may, for example, be a monocoque design, formed of one continuous piece of material. Alternatively, the housing  30  may include two or more pieces (e.g., a top portion and a bottom portion) which are fused or otherwise fastened to one another.  
         [0027]     In step  84 , the primary PCB  60  is positioned within the housing  30  and, in step  86 , the secondary external circuit board  40  is positioned on the housing  30  with the connector  44  aligned with the second opening  36  and corresponding circuitry  62  (e.g., the complementing connector) of the primary PCB  60  for electrical connection to the primary PCB  60  (step  88 ).  
         [0028]     In step  90 , the keypad  52  is positioned in a desired alignment on the secondary external circuit board  40  as described above and, in step  92 , the frame  56  is positioned on the keypad  52  and secured to the housing  30  by, for example, screws, adhesive, fasteners, etc. If necessary, an overlay  58  is positioned over the frame  56  to increase an aesthetic value of the keypad assembly.  
         [0029]     An advantage of the keypad assembly of the present invention is that it saves a considerable amount of space. For example, because the secondary external circuit board  40  is separate from the primary PCB  60 , the primary PCB  60  may be made smaller allowing size of the chamber  31  and the size of the housing  30  to be reduced. Alternatively or additionally, additional circuitry may be placed on the primary PCB  60 , enabling the mobile device  38  to perform an increased number of functions without increasing the size of the primary PCB  60  and the chamber  31 . Also, a greater number of keys  53  may be included in the keypad arrangement, because there is more space available for the larger switches  42  or for an increased number of switches  42 . For example, in some smaller conventional keypad assemblies each key represents a number of letters and/or numbers requiring the user to press keys numerous times when entering a single character. Embodiments of the present invention may allow certain of these keypads to be expanded with separate keys for a larger number of characters. In addition, the present invention may reduce a number of configurations of the primary PCB  60 .  
         [0030]     From the above description of the exemplary embodiments, those of skill in the art will understand that the present invention may reduce space needed for bosses on the keypad area of a mobile device, allowing for the greater number and/or larger keys  53 . The mobile device is designed with the knowledge that space is needed for fastening components of the device, e.g., halves of the housing  30 , the keypad, etc. According to the present invention, fasteners (e.g., screws) may secure the keypad to the cavity  35  and an upper half of the housing  30 .  
         [0031]     It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.