Abstract:
A lower enclosure of a keyboard includes a region forming a cavity to stiffen the lower enclosure and a node support disposed in the cavity to support a node of a circuit in a switch-membrane assembly of the keyboard. With the node support, a plate to support the switch-membrane assembly may be omitted from the keyboard. Thus, the keyboard may be easier and less expensive to manufacture than a keyboard that includes a plate.

Description:
CROSS-REFERENCED APPLICATIONS  
       [0001]     U.S. Design patent application Ser. No. ______, titled PANEL AND SPECIAL FUNCTION KEYS FOR KEYBOARD OR SIMILAR ARTICLE, attorney docket number 200314059-1 (1964-44-5), filed on 12 Mar. 2004, is herein incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     Many computer systems include a processor that receives data and executes instructions, and a keyboard that is coupled to the processor and that allows one to provide data to the processor. The keyboard typically includes many circuits that, when closed individually or in combination with another circuit, generate a respective signal that provides the processor corresponding data. To close a circuit, one typically exerts pressure on a respective key of the keyboard.  
         [0003]      FIG. 1  is an exploded view of a conventional keyboard  10 , which includes a plurality of circuits  12  (only two reference numbers denoting one circuit shown for clarity) and a plate  14  to support the circuits when one or more of circuits are closed. The keyboard  10  also includes a plurality of keys  16  (only two shown for clarity) each corresponding to a respective circuit  12 , an upper enclosure  18  to hold each key  16  and protect components inside the keyboard, and a lower enclosure  20  to support and protect components inside the keyboard. The lower enclosure  20  includes a cavity  21  for stiffening the lower enclosure and providing a passage for the cable  23  that couples the keyboard  10  to a processor (not shown). The keyboard  10  also includes a switch-membrane assembly  22  that includes the circuits  12 . The switch-membrane assembly  22  includes a top sheet  24  having top portions  26  and top nodes  28  of each circuit  12 , a bottom sheet  30  having bottom portions  32  and bottom nodes  34  of each circuit, and an insulating sheet  36  between the top and bottom sheets for insulating the top circuit portions from the bottom circuit portions. The insulating sheet  36  also includes a plurality of holes  38  (only one reference number shown for clarity), each corresponding to a respective set of nodes  28  and  34  for each circuit  12 . The keyboard  10  also includes a plurality of elastic domes  40  (only one reference number shown for clarity), each corresponding to a respective key  16  to urge the key away from the switch-membrane assembly  22 .  
         [0004]     To close a circuit  12  of the switch-membrane assembly  22 , one presses a corresponding key  16  to couple the top portion  28  of the circuit with the bottom portion  32  by causing the top node  28  to contact the bottom node  34 . That is, to contact the top node  28  with the bottom node  34 , one exerts pressure on the key  16 , and thus the corresponding dome  40 , to move the top node  28  through the hole  38  toward the bottom node  34 . The plate  14  supports the bottom node  34  to help establish contact between the top node  28  and bottom node when the top node is moved through the hole  38 . The support function of the plate  14  is especially important if the bottom node  34  is located above the cavity  21 . Without some support, the bottom node  34  would move into the cavity  21  when the top node  28  is moved toward it, and thus the top node may not contact the bottom node to generate a signal. To re-open the circuit  12 , one removes the pressure exerted on the key  16  to allow the elastic dome  40  to urge the key  16  away from the top node  28 , and thus allow the top node to move away from and out of contact with the bottom node  34 .  
         [0005]     Unfortunately, manufacturing the keyboard  10  can be complex and expensive. The plate  14  is typically made of metal and sized to match the area of the switch-membrane assembly  22  to provide the keyboard  10  a desired stiffness during use. In addition, the plate  14  must be located in the keyboard  10  to complete the keyboard&#39;s assembly. Consequently, the cost to manufacture the keyboard  10  includes the cost of the labor and material used to make the plate  14  and the cost of the labor used to install the plate in the keyboard.  
       SUMMARY  
       [0006]     In one aspect of the invention, a keyboard enclosure includes a region forming a cavity to stiffen the lower enclosure and a node support located in the cavity to support a node of a circuit in a switch-membrane assembly of the keyboard. With the node support, a plate to support the switch-membrane assembly may be omitted from the keyboard. Thus, the keyboard may be easier and less expensive to manufacture than a conventional keyboard. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]      FIG. 1  is an exploded view of a conventional keyboard.  
         [0008]      FIG. 2  is an exploded view of a keyboard incorporating a lower enclosure according to an embodiment of the invention.  
         [0009]      FIG. 3  is a plan view of the lower enclosure of  FIG. 2 .  
         [0010]      FIG. 4  is a side view of the keyboard of  FIG. 2 .  
         [0011]      FIG. 5  is a block diagram of an electronic system that includes the keyboard of  FIGS. 2 and 4 . 
     
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 2  is an exploded view of a keyboard  50  that includes a lower enclosure  52  having node supports  54 , according to an embodiment of the invention. The keyboard  50  may be used to provide data to a processor (not shown) for performing various computing functions, such as executing programs to perform specific tasks. Each node support  54  supports a respective circuit node  56  that is located above a cavity  58  formed in the lower enclosure  52 . Each circuit node  56  is a component of a respective one of a plurality of circuits  60  (only four reference numbers shown for clarity) in the keyboard  50  that may generate a signal to provide the processor data as discussed below. Because the node support  54  can support the circuit nodes  56 , the keyboard  50  does not require a plate (e.g.,  14  in  FIG. 1 ) to support the circuit nodes located above the cavity  58 .  
         [0013]     The keyboard  50  also includes a plurality of keys  62  (only one shown for clarity), each corresponding to a respective circuit  60 , and an upper enclosure  64  that includes a plurality of key receptacles  66  (only one reference number shown for clarity) each to hold a respective key  62 . The keyboard  50  also includes a switch-membrane assembly  68  that includes the plurality of circuits  60 . The switch-membrane assembly  68  includes a top sheet  70  having a top portion  72  and a top node  74  of each circuit  60 , a bottom sheet  76  having a bottom portion  78  and a bottom node  56  of each circuit  60 , and an insulating sheet  80  between the top and bottom portions. The insulating sheet  80  also includes holes  82  (only one reference number shown for clarity), each corresponding to a respective set of top and bottom nodes for each circuit  60 . The keyboard  50  also includes a plurality of elastic domes  84  (only one reference number shown for clarity), each corresponding to a respective key  62  and operable to bias the key  62  away from the switch-membrane assembly  68 .  
         [0014]     In operation, when one presses a key  60 , the corresponding circuit  60  in the keyboard  50  generates a respective signal to provide the corresponding data (e.g., an ASCII character such as “A”) to the processor (not shown). That is, when a circuit  60  is closed, it generates a signal, and when a circuit  60  is open, it does not generate a signal. To close a circuit  60 , one exerts pressure on the key  62  that corresponds to the circuit to contact the circuit&#39;s respective bottom node  56  with the top node  74 . If the bottom node  56  is located above the cavity  58 , then a respective node support  54  supports the bottom node to help ensure contact between the top and bottom nodes  74  and  56 , respectively, is maintained while the circuit  60  generates the signal. If the bottom node  56  of the circuit is not located above the cavity  58 , then the floor  86  of the lower enclosure  52  may support the bottom node  56  while the circuit  60  generates the signal. To open the circuit  60 , one removes the pressure from the key  62  to allow a respective elastic dome  84  to move the key away from the switch membrane  68 , and thus, the top node  74  moves away from the bottom node  56  to break the contact between the top and bottom nodes.  
         [0015]      FIG. 3  is a top view of the lower enclosure  52  in  FIG. 2 . The lower enclosure  52  includes a region  90  that forms the cavity  58  and that stiffens the lower enclosure, and node supports  54  disposed in the cavity to support the bottom nodes  56  ( FIG. 2 ) that are located above the cavity. Although  FIG. 3 . shows the lower enclosure  52  including one region  90  that forms a cavity  58 , the lower enclosure may include two or more regions  90  as desired to stiffen the lower enclosure and/or to provide node supports  54  for corresponding bottom nodes  56  or to provide room for other components (not shown) of the keyboard  50  ( FIG. 2 ). Furthermore, the region  90  of the lower enclosure  52  may include two or more cavities  58  as desired to stiffen the lower enclosure, or to provide node supports  54  for corresponding bottom nodes  56 , or to provide room for other components of the keyboard  50 .  
         [0016]     The cavity  58  may have any desired shape. For example, in one embodiment the cavity  58  may have a substantially U-shaped cross-section. In another embodiment, the cavity  58  extends approximately 15.5 inches across the floor  86  of the lower enclosure  52  and includes a bottom wall  92  and a sidewall  94 . In this embodiment, the sidewall  94  extends approximately 0.5 inches between the floor  86  and the bottom wall  92 , and thus provides an approximate cavity depth of 0.5 inches.  
         [0017]     Other embodiments are contemplated. For example, the cavity  58  may have a substantially W-shaped cross-section and, when viewed from above may curve across the floor  86 . For example, when viewed from above, the cavity  58  may form an S, a circular or elliptical arc, or any other such curve.  
         [0018]     Still referring to  FIG. 3 , the lower enclosure  52  may include any number of node supports  54 , and each node support may be located anywhere in the cavity  58  to correspond to a respective circuit node  56  ( FIG. 2 ) that is located above the cavity. Furthermore, each node support  54  may be shaped as desired to support the circuit node  56 . For example, in one embodiment the lower enclosure  52  may include thirteen node supports  54  and each node support  54  may be cylindrically shaped and hollow. Each node support  54  may also extend from the bottom wall  92  toward the floor  86  of the lower enclosure  52 , and include an end  96  that is substantially level with the floor  86 . Thus, the bottom sheet  76  ( FIG. 2 ) typically lies substantially flat when supported by the lower enclosure  52 , and remains substantially flat when the key  62  ( FIG. 1 ) urges a top node  74  ( FIG. 1 ) to contact a bottom node  56  that is located above the cavity  58 .  
         [0019]     Other embodiments are contemplated. For example, the lower enclosure  52  may include more or fewer node supports  54 , and one or more of the node supports  54  may be square shaped, solid and extend from a sidewall  94  of the region  90 . Furthermore, one or more of the node supports  54  may extend from the bottom wall  92  or sidewall  94  to locate the end  96  above or below the floor  86  of the lower enclosure  52 . This may be desirable when other components of the keyboard  50  are located between the bottom sheet  76  and the floor  86 .  
         [0020]     Still referring to  FIG. 3 , the lower enclosure may also include ribs  98  to support the node supports  54  and maintain the position of the node supports  54  relative to the floor  86 . Each rib  98  may extend from a node support  54  toward another node support  54  and/or the bottom wall  92  and/or the sidewall  94 . For example, in one embodiment four ribs  98  may support one of the node supports  54  (see A in  FIG. 3 ). Two of the ribs  98  may extend between the sidewall  94 , the bottom wall  92  and the node support  54 ; and the other two ribs  98  may extend between the node support  54 , adjacent node supports  54 , and the bottom wall  92 . Another node support  54  (see B in  FIG. 3 ) may be supported by four ribs  98  with one of the ribs  98  extending between the bottom wall  92  and the node support  54 ; not the sidewall  94  or other node supports  54 . And yet another node support  54  (see C in  FIG. 3 ) may be supported by two ribs  98  with one of the ribs  98  extending between the node support  54 , the bottom wall  92  and the sidewall  94 , and the other rib  98  extending between the node support  54 , an adjacent node support  54  and the bottom wall  92 .  
         [0021]     Still referring to  FIG. 3 , the lower enclosure  52  may be made from any desirable material using any desired manufacturing process. For example, in one embodiment the lower enclosure  52  may be made of conventional plastic and cast as one piece from a mold. Thus, the node supports  54  and ribs  98  may be an integral part of the formed lower enclosure  52 . In other embodiments, the node supports  54  and ribs  98  may be fastened to the lower enclosure  52  using any desired means, such as gluing with an adhesive.  
         [0022]      FIG. 4  is a side view of the keyboard in  FIG. 2  assembled and positioned on a surface  100 , according to an embodiment of the invention. When the keyboard  50  is assembled, the upper enclosure  64  may be mounted to the lower enclosure  52  to protect the switch-membrane assembly  68  ( FIG. 2 ), elastic domes  84  ( FIG. 2 ) and other components of the keyboard  50  that may be located between the upper and lower enclosures  64  and  52 , respectively. To position the keyboard  50  on the surface  100  as shown, the lower enclosure  52  may include a leg  102  that may be extended from the region  90 . For example, in one embodiment the leg  102  may contact the surface  100  at a substantially perpendicular angle. Furthermore, the region  90  may be formed to position the bottom wall  92  substantially parallel to the surface  100  when the keyboard  50  is positioned as shown. Thus, each node support  54  may be angled relative to the bottom wall  92  so that each node support&#39;s end  96  ( FIG. 3 ) remains substantially parallel with the floor  86 .  
         [0023]      FIG. 5  is a block diagram of an electronic system  110  that incorporates the keyboard  50  ( FIGS. 2 and 4 ). The system  110  includes computer circuitry  112 , which includes a processor  114  and a memory  116  coupled to the processor, for performing computer functions such as executing software to perform desired calculations and tasks. One or more input devices  118  that includes the keyboard  50  and may include other devices such as a mouse or microphone, are coupled to the computer circuitry  112  and allow an operator (not shown) to input data thereto. One or more output devices  120  are coupled to the computer circuitry  112  to provide to the operator data generated by the computer circuitry  112 . Examples of such output devices  120  include a printer and a video display unit. One or more data-storage devices  122  are coupled to the computer circuitry  112  to store data on or to retrieve data from external storage media (not shown). Examples of such storage devices  122  and the corresponding storage media include drives that accept hard and floppy disks, tape cassettes, and compact disk read-only memories (CD ROMS).  
         [0024]     The preceding discussion is presented to enable one skilled in the art to make and use the invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.