Patent Publication Number: US-6903925-B2

Title: Keyswitch for keyboard of notebook computer

Description:
This nonprovisional application claims priority under 35 U.S.C. § 119(a) on patent application No. 91210653 filed in TAIWAN on Jul. 12, 2002, which is herein incorporated by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to a keyswitch for keyboard of notebook computer, especially to a keyswitch with lever mechanism for keyboard of notebook computer. 
   BACKGROUND OF THE INVENTION 
   Conventional keyswitches with lever mechanism (scissors type keyswitch) are extensively used in keyboard for notebook computer.  FIG. 1  shows a conventional keyswitch with a keycap  10   a , a first lever  11   a , a second lever  12   a  and a base  13   a , wherein the first lever  11   a  and the second lever  12   a  are cross to each other. The first lever  11   a  has a pivotal shaft  14   a  pivotally connected to a pivotal stage  16   a  on the base  13   a  and the second lever  12   a  has a pivotal shaft  15   a  pivotally connected to a pivotal stage  17   a  on the base  13   a , respectively. Each of the first lever  11   a  and the second lever  12  has a top end connected to a bottom face of the keycap  10   a , whereby the first lever  11   a  and the second lever  12  form a lever mechanism. 
   The first lever  11   a  of the lever mechanism has a bump  18   a  placed at a lower center end thereof and the base  13   a  has a flange  19   a  on top face thereof and corresponding to the bump  18   a . The bump  18   a  is in contact with and clamped by the flange  19   a  during downward stroke of the keycap  10   a.    
   A rubber dome (not shown) is placed between the keycap  10   a  and the base  13   a . When the keycap  10   a  is guided by the lever mechanism for vertical up and down movement, the rubber dome below the keycap  10   a  will detach from or touch a flexible circuit board (not shown) on the base  13   a  and a switch on the flexible circuit board is turned off or on. 
   However, the conventional keyswitch for notebook computer has the problem of rotation and shaking. The keyswitches with lever mechanism have limitation of further improvement. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a keyswitch for keyboard of notebook computer and having enhanced stability during the key pressing stroke. 
   To achieve above object, the present invention provides a keyswitch for keyboard of notebook computer comprising a keycap; a base arranged below the keycap and having two protuberances thereon; and a lever mechanism. The lever mechanism has a plurality of top ends connected to the keycap and a plurality of lower ends connected to the base. The lever mechanism has two projections located on lower lateral edges thereof and corresponding to the protuberances. During a downward stroke of the keycap, the projections of the lever mechanism will be in contact with the protuberances, whereby the stability of the keyswitch will be enhanced. 
   The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows an exploded view of a conventional keyswitch for keyboard of notebook computer; 
       FIG. 2  shows an exploded view of a keyswitch for keyboard of notebook computer according to the present invention; 
       FIG. 3  shows another exploded view of a keyswitch for keyboard of notebook computer according to the present invention; 
       FIG. 4  shows a perspective view of a keyswitch for keyboard of notebook computer according to the present invention; 
       FIG. 4A  shows a partially enlarged view of part A in  FIG. 4 ; 
       FIG. 5  shows an exploded view of a keyswitch for keyboard of notebook computer according to another preferred embodiment of the present invention; and 
       FIG. 6  shows an exploded view of a keyswitch for keyboard of notebook computer according to still another preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 2  to  4 , the present invention provides a keyswitch for keyboard of notebook computer and the keyswitch comprises a keycap  10 , a first lever  20 , a second lever  30  and a base  40 . The keycap  10  is of rectangular shape and having an operative face  11  and an assembling face  12 . 
   The first lever  20  and the second lever  30  are placed between the assembling face  12  of the keycap  10  and the base  40 . The first lever  20  has a plurality of pivotal openings  21  and the second lever  30  has corresponding pivotal shafts  31  such that the first lever  20  and the second lever  30  can be assembled to form lever mechanism. 
   The first lever  20  has two first connection shafts  22  on two lateral upper edges thereof and the second lever  30  has two second connection shafts  32  on two lateral upper edges thereof. The first lever  20  and the second lever  30  are assembled to the assembling face  12  by the first connection shafts  22  and the second connection shafts  32 , respectively. Therefore, the first lever  20  and the second lever  30  are assembled to the keycap  10  on top ends thereof. 
   The first lever  20  has two first pivotal shafts  23  on two lateral lower edges thereof and the second lever  30  has two second pivotal shafts  33  on two lateral lower edges thereof. The first lever  20  and the second lever  30  are assembled to the base  40  by the first pivotal shafts  23  and the second pivotal shafts  33 , respectively. 
   The base  40  is made of metal plate and arranged below the keycap  10 , the first lever  20 , and the second lever  30 . The base  40  has first pivotal stages  41  and second pivotal stages  42  corresponding to the first pivotal shafts  23  and the second pivotal shafts  33 . The first pivotal shafts  23  and the second pivotal shafts  33  are pivotally connected to the first pivotal stages  41  and second pivotal stages  42  such that the first lever  20  and the second lever  30  are assembled to the base  40  on lower ends thereof. 
   The keycap  10  has rubber dome (not shown) and flexible circuit board (not shown) therebelow. When the keycap  10  is guided by the lever mechanism for vertical up and down movement, the rubber dome below the keycap  10  will detach from or touch the flexible circuit board and a switch (not shown) on the flexible circuit board is turned off or on. 
   In the present invention, the first lever  20  has two projections  24  thereon and formed in one piece form with the first lever  20 . The projection  24  has arbitrary shape such as rectangular shape. The two projections  24  can be formed on two lateral lower edges of the first lever  20 . For example, the two projections  24  can be formed on inner faces or outer faces of two lateral lower edges of the first lever  20 . In the preferred embodiment shown in  FIG. 3 , the two projections  24  are formed on the first lever  20 . Moreover, as shown in  FIG. 5 , the two projections  24  can also be formed on the second lever  30 . Alternatively, the projections  24  can also be formed both on the first lever  20  and the second lever  30 . The two projections  24  can be faced to each other or staggered to each other, alternatively, arranged diagonally as shown in FIG.  6 . Moreover, the number of the projections  24  can be increased to three or four, depending on practical situation. 
   Moreover, the base  40  has two protuberances  43  projecting out of the top face of the base  40  and placed corresponding to the projections  24 . The two protuberances  43  are formed in one piece form with the base  40 . The protuberances  43  can have arbitrary shapes such as rectangular or circular shapes. The two protuberances  43  are located at predetermined locations on inner side of each first pivotal stage  41  and having predetermined separation with the first pivotal stage  41 . The positions of the protuberances  43  may be changed with the positions of the projections  24 . T he two protuberances  43  can be faced to each other or staggered to each other, alternatively, arranged diagonally. Moreover, the number of the protuberances  43  can be increased to three or four, depending on practical situation. 
   With reference now to  FIG. 4A , during the downward stroke of the keycap  10 , the projections  24  on the first lever  20  of the lever mechanism will be in contact with the protuberances  43  and positioned by the protuberances  43 . The stability of the keyswitch during key pressing operation is enhanced. 
   Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.