Abstract:
A support linkage movably connecting a key cap to a plastic body comprises a first rack and a second rack. The first rack has a first rack body movably connected between the key cap and the plastic body, and the second rack has a second rack body movably connected between the key cap and the plastic body. The second rack body has two axial holes each having an open side and engaged with a shaft on the first rack body.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This Patent Application is a Continuation-in-Part Application of application Ser. No. 09/108,219, filed Jul. 1, 1998, and entitled KEYSET OF KEYBOARD. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a support linkage for keyswitch, more particularly, to a support linkage for keyswitch, which can be easily assembled and is not liable to deform or break during assembling. 
     BACKGROUND OF THE INVENTION 
     The conventional keyset for notebook computer generally comprises a key cap  2 , a first rack  1 , a second rack  3 , a flexible circuit board  4 , a resilient body  6 , and a base plate  5 . 
     As shown in FIG. 1 and 2, the conventional first rack  1  and second rack  2  are arranged in scissors arrangement. When the key cap  2  is guided by the first rack  1  and the second rack  3  to move upward and downward, whereby the body  6  below the key cap  2  can press on or detach from the flexible circuit board  4  to turn on or turn off the keying. 
     However, the lateral sides of the rack  1 ,  3  in conventional art have not sufficient strength such that the racks are liable to deform or break during assembling or detach. Moreover, the assembling of those racks is not easy and requires precise alignment to prevent jamming. 
     It is the object of the present invention to provide a support linkage for keyswitch, the racks thereof are designed to have easy assembling without the usage of auxiliary tools, and have better strength to prevent the deforming and breaking during assembling or disassemble. 
     To achieve the above object, the support linkage for keyswitch according to the present invention comprises a first rack and a second rack. The first rack has a first rack body movably connected between the key cap and the plastic body, and the second rack has a second rack body movably connected between the key cap and the plastic body. The second rack body has two axial holes each having an open side and engaged with a shaft on the first rack body. 
     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 the perspective exploded view of the conventional keyset. 
     FIG. 2 is the perspective view of the scissors-type rack in conventional keyset. 
     FIG. 3 is a perspective exploded view of the preferred embodiment of the invention. 
     FIG. 4 is the perspective view of the second rack of the preferred embodiment according to the invention 
     FIG. 5 is the top view of the second rack of the preferred embodiment according to the invention. 
     FIG. 6 is the cross section view of the second rack of the preferred embodiment according to the invention. 
     FIG. 7 is the perspective view of the first rack of the preferred embodiment according to the invention 
     FIG. 8 is the top view of the first rack of the preferred embodiment according to the invention. 
     FIG. 9 is the cross section view of the first rack of the preferred embodiment according to the invention. 
     FIG. 10 is a top view shows the first and second racks of the preferred embodiment according to the invention in scissors arrangement. 
     FIG. 11 is a perspective view shows the first and second racks of the preferred embodiment according to the invention in scissors arrangement. 
     FIG. 12 is a view showing the operation of the preferred embodiment according to the invention. 
     FIG. 13 is another view showing the operation of the preferred embodiment according to the invention. 
     FIG. 14 is a cross sectional view of an alternate configuration of the second rack of the present invention. 
     FIG. 15 is a cross sectional view of another alternate configuration of the second rack of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 3 is a perspective view of the preferred embodiment of the present invention. A support linkage of this preferred embodiment includes a keycap  12 , a first rack  13 , a second rack  1 , a plastic body  17 , a soft printed circuit board  14 , a resilient body  16 , and a base plate  15 . The rectangular-shaped keycap  12  has two embedding parts  121  (FIG. 12) on one upper lateral side within the inner space thereof to clamp the first rack  13  and two retaining grooves  123  (also shown in FIG. 12) on the other upper lateral side to clamp the second rack  11 . 
     The first rack  13  is arranged below the keycap  12  and the keycap  12  is in a scissor-like arrangement with the second rack  11 . The retaining grooves  134  of the first rack  13  engage with the embedding parts  121  of the keycap  12 . The second rack II includes a fourth shaft  115  to engage with the retaining grooves  123  of the keycap  12 . 
     The plastic body  17  is arranged below the first rack  13  and the second rack  11 . The plastic body  17  is provided with a through hole for the penetration of the resilient body  16  on the location corresponding to the keycap  12 . Two axial holes  118  are set on both sides of the second rack  11  and these axial holes are used to engage with the first rack  13 . 
     The resilient body  16  is arranged below the first rack  13  and the second rack  11  and is within the through hole of the plastic body  17 . The resilient body  16  is functioned to support the first rack  13  and the second rack  11 . 
     The soft printed circuit board  14  is arranged below the plastic body  17  and the base plate  15  is set below the soft printed circuit board  14 . 
     Please refer to FIGS. 4-6, FIG. 4 is a schematic diagram of the second rack  11 , FIG. 5 is a top view of the second rack  11 , and FIG. 6 is a side view of the second rack  11 . The second rack  11  includes two opposed rack bodies  113 , both of which are connected by a connection part  112  and an arc-shaped part  114 . One end of each rack body  113  has a fourth shaft  115  opposed to its counterpart, and two third shafts  117  extend from the other two ends of the rack bodies  113 . The axial holes  118  are set on two rack bodies  113  respectively. Each of the axial holes  118  has an open side as shown as in FIG.  4 . 
     Please refer to FIGS. 7-9, FIG. 7 is a schematic diagram of the first rack  13 , FIG. 8 is a top view of the first rack  13 , and FIG. 9 is a side view of the first rack  13 . The first rack  13  has an inverse-U shaped rack body  131 , including a U-shaped arm portion  133  on the inner side thereof. Please refer to FIG. 4 in conjunction with FIG. 7, the arm portion  133  has two second shafts  135  on two lateral sides thereof and their locations are corresponding to those of the axial holes  118  of the second rack  11 . Moreover, the width of the open side of the axial hole  118  is smaller than the maximum width of the second shaft  135 , leading to the second shaft  135  can be easily assembled into the axial hole  118  and retained within the axial hole  118  stably. 
     The inverse-U shaped rack body  131  also includes a connection side  139  and two grooves  134  are set on two ends of the connection body  139  respectively. These grooves  134  are set to engage with corresponding embedding parts  121  of the keycap  12  (shown in FIG.  12 ). Two first shafts  132  are set on the inverse-U shaped rack body  131  for engaging with the plastic body  17  (also shown in FIG.  12 ). 
     Please refer to FIG.  10  and FIG. 11, FIG.  10  and FIG. 11 is a top view and a schematic diagram respectively while the first rack  13  engages with the second rack  11 . The U-shaped arm portion  133  is set on the inner side of the first rack  13 , resulting in the contact area between the first rack  13  and the second rack  11  increases to prevent the shaky problem of the keycap and make the assembly and the disassembly of the keycap easier. Because of the special slope design of the axial holes  118  of the second rack  11 , there is no specific direction or angle while assembling the first rack  13  and the second rack  11 . Furthermore, the bearing of the second rack  11  is on the innermost side of the U-shaped arm portion  133  of the first rack  13 , and that&#39;s why the distortion or the breaking of those two racks can be prevented. 
     Please refer to FIG.  12  and FIG.  13 . FIG. 12 is a side view of the present invention, and FIG. 13 is a side view while the present invention is pressed. When the keycap  12  is pressed, it will be guided by the first rack  13  and the second rack  11  to move downward in a vertical direction. The keycap  12  will lead the resilient body  16  to press the soft printed circuit board  14  to generate a corresponding key signal. If the force is not pressed on the keycap  12 , the keycap  12  will be moved upward because of he resilient force of the resilient body  16  and guided by the first rack  13  and the second rack  11 , leading to the resilient body  16  does not press the soft printed circuit board  14  anymore and thus generates no key signal. 
     Please refer to FIG.  14  and FIG. 15, FIG.  14  and FIG. 15 are two embodiments of the second rack  11 . The shape of the axial hole  118  is not symmetric, and thus the second shafts  135  will engage with and retain within the axial holes  118  more tightly. As shown in FIG. 15, the axial hole  118  has a bevel surface near the open side for facilitating the automatic production. 
     To sum up, the inventive support linkage can solve the poor assembly and weak strength problems of its conventional counterparts. 
     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 been suggested in the foregoing description, and others 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.