Patent Publication Number: US-6340803-B1

Title: Computer keyswitch

Description:
FIELD OF THE INVENTION 
     The present invention relates to a computer keyswitch, especially to a computer keyswitch suitable for notebook computer, which has lower height but with same level mechanism height and structural strength. 
     BACKGROUND OF THE INVENTION 
     FIG. 1 shows a prior art computer keyswitch  10   a , which comprises a keycap  11   a , a resilient body  12   a , a first lever  13   a , a second lever  14   a , a base  15   a  and a bottom plate  16   a . The first lever  13   a  and the second lever  14   a  are in scissors arrangement and have pivotal shafts  17   a  and  18   a  on bottom ends thereof. The pivotal shafts  17   a  and  18   a  are pivotally retained below clamping plates  19   a  and  20   a  formed on topside of the base  15   a . The top ends of the first lever  13   a  and the second lever  14   a  are connected to the bottom side of the keycap  11   a . The first lever  13   a  and the second lever  14   a  form the level mechanism of the keyswitch and the resilient body  12   a  is placed within the movement stroke of the level mechanism. When the keycap  11   a  is guided by the level mechanism composed of the first lever  13   a and the second lever  14   a  to move downward or upward, the resilient body  12   a  below the keycap  11   a  presses on a membrane circuit  21   a  or leaves the membrane circuit  21   a  to perform on and off operation of the membrane circuit  21   a.    
     However, in above-mentioned computer keyswitch  10   a , the pi pivotal shafts  17   a  and  18   a  of the first lever  13   a  and the second lever  14   a  should have sufficient thickness to ensure enough structural strength. The base  15   a  should have considerable thickness and the thickness thereof is much larger than that of the bottom plate  16   a . Therefore, the clamping plates  19   a  and  20   a  formed on topside of the base  15   a  extend to a considerable height. Therefore, the height of the above-mentioned computer keyswitch  10   a  can not be reduced satisfactorily. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a computer keyswitch, which has lower height but with same level mechanism height and structural strength. 
     To achieve the above object, the computer keyswitch according to the present invention comprises clamping plate extended upward from the bottom plate thereof. The clamping plate is used to retain the upward motion of the pivotal shafts on bottom end of the two levers of the computer keyswitch. The position, orientation and height of the clamping plate has not limit such that the clamping plate has reduced thickness and height. Therefore, the computer keyswitch has lower height but with same level mechanism height and structural strength. 
     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 DRAWING 
     FIG. 1 is a section view of prior art computer keyswitch; 
     FIG. 2 is the exploded view of the computer keyswitch of the present invention; 
     FIG. 3 is the perspective view of the computer keyswitch of the present invention; 
     FIG. 4 is the sectional view of the computer keyswitch of the present invention; and 
     FIG. 5 is the sectional view of the computer keyswitch of the present invention in a pressed down state. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to FIGS. 2 to  4 , the present invention provides a computer keyswitch, which comprises a keycap  10 , a resilient body  20 , a first lever  30 , a second lever  40 , a base  50  and a bottom plate  60  and a membrane circuit  70 . The keycap  10  is of rectangular plate shape and has an operating surface  11  and a mounting surface  12 . The mounting surface  12  has two pivotal holes  13  and two sliding grooves  14 . 
     The resilient body  20  is placed below the keycap  10  and within the movement stroke of the keycap  10 . 
     The first lever  30  and the second lever  40  are arranged between the mounting surface  12  and the base  50 . The first lever  30  and the second lever  40  have corresponding pivotal shafts  31  and pivotal holes  41  on center part thereof, respectively, such that the first lever  30  and the second lever  40  are arranged in scissors fashion. The first lever  30  has two pivotal shafts  32  on two top ends thereof and the second lever  40  has two sliding shafts  42  on two top ends thereof. The first lever  30  and the second lever  40  are assembled to the mounting surface  12  by pivotally assembling the two pivotal shafts  32  to the two pivotal holes  13  and slidably assembling the two sliding shafts  42  to the two sliding grooves  14 . The first lever  30  has a pivotal shaft  33  on bottom side thereof and the second lever  40  has two pivotal shafts  43  on two bottom ends thereof such that the first lever  30  and the second lever  40  are pivotally assembled to the bottom plate  60 . 
     The base  50  is placed below the keycap  10 , the first lever  30  and the second lever  40 , and has a specific thickness. The base  50  has an accommodating space  51  thereon and the first lever  30  and the second lever  40  are placed atop the accommodating space  51 . Therefore, the first lever  30  and the second lever  40  can be accommodated by the accommodating space  51 . 
     The bottom plate  60  is placed below the base  50  and is a plate with thinner thickness. Nevertheless, the thickness can be changed according to practical situation. The bottom plate  60  has a plurality of through holes  61  and  62  corresponding to the pivotal shafts  33  and  43  of the first lever  30  and the second lever  40 . The pivotal shafts  33  and  43  of the first lever  30  and the second lever  40  are pivotally assembled into the through holes  61  and  62  of the bottom plate  60 . The bottom plate  60  has a plurality of clamping plates  63  and  64  extended from topside of the through holes  61  and  62  of the bottom plate  60 . The clamping plates  63  and  64  are used to confine upward motion of the pivotal shafts  33  and  43  of the first lever  30  and the second lever  40 . The position, orientation and height of the clamping plates  63  and  64  have not limit as long as the clamping plates  63  and  64  can confine upward motion of the pivotal shafts  33  and  43  of the first lever  30  and the second lever  40 . In the preferred embodiment of the present invention, each of the clamping plates  63  and  64  has reversed-L shape. The number of the clamping plates  63  and  64  can also be changed according to practical usage. In the preferred embodiment of the present invention, the number of the clamping plate  63  is 1 and the number of the clamping plate  64  is 2. The two clamping plates  64  are located at front side and the clamping plate  63  is located at rear side and between the two clamping plates  64  such that the clamping plates  63  and  64  form a triangular pattern. 
     The membrane circuit  70  is placed atop the bottom plate  60  and below the resilient body  20 . The membrane circuit  70  has a plurality of through holes  71  and  72  corresponding to the pivotal shafts  33  and  43  on bottom of the first lever  30  and the second lever  40 . Therefore, the pivotal shafts  33  and  43  on bottom of the first lever  30  and the second lever  40  are pivotally assembled into the through holes  61  and  62  of the bottom plate  60 . 
     As shown in FIG. 5, when the keycap  10  is guided by the level mechanism composed of the first lever  30  and the second lever  40  to move downward or upward, the resilient body  20  below the keycap  10  presses on a membrane circuit  70  or leaves the membrane circuit  70  to perform on and off operation of the membrane circuit  21   a . When the keycap  10  is guided by the first lever  30  and the second lever  40  to move downward, the first lever  30  and the second lever  40  sink into the accommodating space  51 . Therefore, the overall height of the keyswitch is reduced while the movement stroke of the keyswitch is not changed. Moreover, the accommodating space  51  enable the first lever  30  and the second lever  40  to assemble from bottom of the base  50 . 
     The present invention is characterized in that the clamping plates  63  and  64  are extended from the bottom plate  60 . The thickness of the bottom plate  60  has not limit and can adopt thinner thickness. Therefore, the clamping plates  63  and  64  can also have thinner thickness. The pivotal shafts  33  and  43  on bottom of the first lever  30  and the second lever  40  are retained by the clamping plates  63  and  64 . Therefore, the height of the pivotal shafts  33  and  43  can also be reduced. The keyswitch has lower height but with same level mechanism height and structural strength. 
     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.