Abstract:
A portable foldable keyboard comprised of two housings, each of which contains a key assembly, and a central hinge. The two housings can be slid together when the keyboard is unfolded and they interlock to form a sturdy keyboard having the standard QWERTY keyswitch layout.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a foldable keyboard, and more particularly to a foldable keyboard that is easy to manufacture and that is sufficiently rigid when unfolded such that it can be utilized while it is positioned on a user&#39;s lap. Keyboards embodying this invention are particularly useful when combined with personal data assistants (“PDAs”).  
         DESCRIPTION OF RELATED ART  
         [0002]    The need exists for a PDA sized, efficient, low cost portable keyboard. Although several versions of foldable or portable keyboards, which are useable with PDAs, have been patented or introduced into the market, none of the existing keyboards satisfy the need for a PDA sized, efficient, low cost portable keyboard. Each of the existing keyboards exhibits one or more of the following drawbacks: they are substantially larger than a PDA even when folded; their unfolded length extends substantially beyond the useable keyswitch area; the keyswitch layouts do not comply with the standard QWERTY keyswitch layout used by most U.S. keyboards; they are overly complex and consist of many parts; and they lack sufficient rigidity for efficient lap-top use.  
           [0003]    For example, U.S. Pat. No. 5,941,648, discloses a foldable keyboard that can be used with a PDA. The keyboard disclosed in U.S. Pat. No. 5,941,648 is divided into curved halves connected together by a single hinge. When this prior art keyboard is unfolded for use, its keyswitch layout is not in conformance with the standard QWERTY keyswitch layout. Additionally, it is not sufficiently rigid to be typed on when in a user&#39;s lap. Further, the keyboard disclosed in U.S. Pat. No. 5,941,648 is substantially larger than a PDA even when it is folded  
           [0004]    The Stowaway Portable Keyboard, which is sold by Think Outside, Inc., discloses a foldable keyboard having four segments connected together by three hinges. Each segment is comprised of a housing and a keyswitch assembly. When the Stowaway Portable Keyboard is unfolded a gap exists between the keys on the first segment of the keyboard and the keys on the second segment and a gap exists between the keys on the third segment of the keyboard and the keys on the fourth segment. The keyswitch assemblies may be slid together to close the gaps between the keys and to place the keyswitches into the standard QWERTY keyswitch layout. However, the housings are not slid together. Accordingly, a substantial amount of unused space exists on the outer sides of the first segment of the keyboard and the second segment of the keyboard making the keyboard unnecessarily long. Additionally, a keyboard having four segments and three hinges is difficult to manufacturer and requires a large number of parts, which results in a high manufacturing cost.  
         SUMMARY OF THE INVENTION  
         [0005]    Embodiments of this invention provide an efficient, low cost portable keyboard that can be used with a PDA as well as other portable microprocessor based equipment. The preferred embodiment of this invention is a keyboard separated into two halves, which can be folded together when the keyboard is not in use. When the keyboard is folded, the keyboard is approximately the size of a PDA and it can be carried in a user&#39;s pocket. When the keyboard is unfolded, the two halves can be slid together using a unique sliding interlock mechanism. This unique sliding interlock mechanism, which requires only a few parts and is easy to manufacture, allows the two keyboard halves to form a single keyboard that does not flex in the middle and that has a sturdiness similar to that of a one piece keyboard. Additionally, when the two halves of the keyboard are slid together, the keyboard&#39;s keyswitches are in a standard QWERTY keyswitch layout and the width of the keyboard does not extend beyond the useable keyswitch area.  
           [0006]    Additionally, the preferred embodiment of this invention utilizes a key membrane cable, which transmits electrical signals from the keyswitches, that utilizes a folded region to facilitate sliding the two keyboard halves together and apart.  
           [0007]    Further, the preferred embodiment of this invention utilizes a PDA connector that automatically pops up when the keyboard is unfolded to facilitate connecting a PDA to the keyboard.  
           [0008]    These and other objects, features, and advantages of the present invention will become more apparent in light of the following detailed description and accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The present invention will be more easily understood with reference to the following drawings.  
         [0010]    [0010]FIG. 1 is an exploded top view of the preferred embodiment of the present invention.  
         [0011]    [0011]FIG. 2 is a is a top view of the preferred embodiment of the present invention in its closed condition.  
         [0012]    [0012]FIG. 2A is a side view of the preferred embodiment of the present invention in its closed condition.  
         [0013]    [0013]FIG. 3 is a top view of the preferred embodiment of the present invention in its open non-interlocked position.  
         [0014]    [0014]FIG. 3A is a side view of the preferred embodiment of the present invention in its open non-interlocked position.  
         [0015]    [0015]FIG. 4 is a top view of a hinge plate used in the preferred embodiment of the present invention showing two key membrane cables.  
         [0016]    [0016]FIG. 5 is a top view of the preferred embodiment of the present invention in its open interlocked position.  
         [0017]    [0017]FIG. 5A is a side view of the preferred embodiment of the present invention in its open interlocked position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    A description of a preferred embodiment of the present invention will now be given.  
         [0019]    [0019]FIG. 1 shows an exploded top view of a keyboard embodying the present invention. The keyboard is comprised of a right housing  1 , a left housing  2 , a right hinge plate  3 , a center hinge  4 , hinge pins  5 , right key assembly  6 , left key assembly  7 , key membrane cable  8 , PCB membrane cable  9 , PCB  10 , PCB housing  11 , PDA membrane cable  12 , PDA connector  13 , PDA connector holder  14 , screws  15 , PDA support  16 , PDA support wire  17 , and locking latch  18 .  
         [0020]    Right hinge plate  3  is positioned in right housing  1  and right key assembly  6  is positioned above right hinge plate  3  in right housing  1 . Screws  15 , which are inserted from the bottom of right housing  1 , pass through elongated openings  20  in hinge plate  3  and into right key assembly  6 . Left key assembly  7  is inserted into left housing  2  and affixed thereto through the use of screws  15 . Center hinge  4  is connected to right hinge plate  3  and left housing  2  through the use of four hinge pins  5 . Locking latch  18  is affixed to the outer side of left housing  2  through the use of two pins  25 . PDA support  16  is slidably inserted into left housing  2  and PDA support wire  17  is rotatably mounted into PDA support  16 . Key membrane cable  8 , which transmits electrical signals from the keyswitches  19 , is connected to the left key assembly  7  and the right key assembly  6 . PCB membrane cable  9 , which transmits electrical signals from the keyswitches  19  to the PCB  10 , is connected to left key assembly  7 . PCB  10  is affixed to left housing  2  and it is held in place by PCB housing  11  through the use of screws  15 . PDA membrane cable  12  is connected to left key assembly  7  and to PDA connector  13 , which is mounted inside of PDA connector holder  14 . PDA connector holder  14  is rotatably mounted in PCB housing  11 .  
         [0021]    A PDA or other portable microprocessor based equipment can be connected to the keyboard through the use of PDA connector  13 . When a PDA is connected to the keyboard, PDA support  16  should be positioned in its extended position as shown in FIG. 5 and PDA support wire  17  should be rotated to its upright position as shown in FIG. 1. PDA support wire  17  provides support for the connected PDA and PDA support  16  maintains PDA support wire  17  in its upright position against the weight of the PDA. When a PDA is not connected to the keyboard, PDA support wire  17  should be rotated to its lowered position and PDA support  16  should be positioned in its inserted position as shown in FIG. 3.  
         [0022]    [0022]FIG. 2 is a top view of the keyboard in its closed condition and FIG. 2A is a side view of the keyboard in its closed condition. The keyboard is closed by folding right housing  1  over left housing  2  or vice versa. Center hinge  4  rotates about left housing  2  and right housing  1  rotates about center hinge  4 . Accordingly, in the closed condition, center hinge  4  is perpendicular to both left housing  2  and right housing  1 . Locking latch  18  latches onto right housing  1  to securely fasten the two halves of the keyboard together.  
         [0023]    [0023]FIG. 3 shows a top view of the keyboard in its open non-interlocked position and FIG. 3A shows a side view of the keyboard in its open non-interlocked position. The keyboard is opened by unfolding right housing  1  from left housing  2 . Center hinge  4  rotates about left housing  2  and right housing  1  rotates about center hinge  4 . Accordingly, in the opened non-interlocked condition, center hinge  4  is in the same plane as and in between left housing  2  and right housing  1 . Additionally, the left edge of right hinge plate  3 , which is connected to center hinge  4 , is coextensive to the left edge of slidable extender portion  21  of right housing  1 . The right edge of right hinge plate  3  is inset from the right edge of right housing  1  by a distance at least equal to the length of slidable extender portion  21  of right housing  1 .  
         [0024]    [0024]FIG. 4 shows right hinge plate  3  and it shows the two key membrane cables  8 . The key membrane cables  8  have a folded area  22  in the cut out slot of right hinge plate  3 . This folded area stores extra cable length to allow sliding of key assembly  6  and right housing  1  into open interlocked position &amp; open non-interlocked position. The amount of fold in the folded area  22  is at its maximum when the keyboard is in its open interlocked position, is at its minimum when the keyboard is in its closed condition, and is intermediate when the keyboard is in its open non-interlocked position.  
         [0025]    [0025]FIG. 5 shows a top view of the keyboard in its open interlocked position and FIG. 5A shows a side view of the keyboard in its open interlocked position. The keyboard is changed from the open non-interlocked position to the open interlocked position by sliding the right housing  1  and the left housing  2  together. Slidable extender portion  21  of right housing  1  extends past center hinge  4  and slides over a portion of left housing  2 . Additionally, when the two halves of the keyboard are slid together, right hinge plate  3  slides inside right housing  1  such that the right edge of hinge plate  3  is adjacent to the right edge of right housing  1  when the keyboard is in its open interlocked position. Accordingly, the right edge of center hinge  4  is contiguous with the left edge of right key assembly  6 , except that the hinge portions of right hinge plate  3  extend between center hinge  4  and right key assembly  6 . In the open interlocked position, the keyswitches  19  of the keyboard are in the standard QWERTY configuration and no part of right housing  1  or left housing  2  is not covered by either right key assembly  6  or left key assembly  7 .  
         [0026]    As shown in FIG. 1, PDA connector  13  is mounted inside PDA connector holder  14  and PDA connector holder  14  is rotatably mounted in PCB housing  11 . This rotatable mounting is accomplished by inserting insertion pin  23  of PDA connector holder  14  into opening  24  of PCB housing  11 . Insertion pin  23  and opening  24  are manufactured such that they elastically deform when PDA connector  13  and PDA connector holder  14  are pressed down parallel with the top of PCB housing  11 , such as happens when the keyboard is placed into its closed position. This elastic deformation causes a resilient force to be applied to the connector holder  14 , thereby, causing connector holder  14  and PDA connector  13  to rotate upward (pop up) when the keyboard is opened.  
         [0027]    The drawings and descriptions of the preferred embodiment are made by way of example rather than to limit the scope of the inventions, and they are intended to cover, within the spirit and scope of the inventions, all such changes and modifications within the spirit of the invention.