Abstract:
A rocking key includes a keycap and a pair of supporting arms. The keycap includes at least two posts, a rib portion positioned between the two posts for preventing the two posts from being simultaneously depressed downwardly. The supporting arms are arranged at two opposite sides of the keycap for resiliently supporting the keycap.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a function key and, more particularly, to a rocking key and an electrical switch assembly employing the same. 
   DESCRIPTION OF RELATED ART 
   In recent years, electronic apparatuses, such as wireless communication apparatuses and portable computers, have undergone significant reductions in size, and thus have become easier to transport and to be used in various environments. In these electronic apparatuses, electrical switches or switch assemblies with rocking keys are generally applied for users to operate. The rocking keys may generally be used as direction control inputting components which can be switched to move cursors on screens of the electronic apparatuses forward/backward or upward/downward. 
   The electrical switch assemblies and, particularly, the rocking keys are reduced in size in order to be compatible within the electronic apparatuses. However, a center portion of the rocking key is liable to be depressed because the rocking key is small. The rocking key is deformed because it is generally made of resilient plastic. Two ends of the rocking key move downward at the same time to activate a relative circuit. Reliability of the electrical switch assembly may be adversely affected. 
   Therefore, a rocking key and an electrical switch assembly employing the same with high reliability are desired. 
   SUMMARY OF THE INVENTION 
   A rocking key including a keycap and a pair of supporting arms is provided. The keycap includes at least two posts, a rib portion positioned between the two posts for preventing the two posts from being simultaneously depressed downwardly. The supporting arms are arranged at two opposite sides of the keycap for resiliently supporting the keycap. 
   Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a rocking key in accordance with a first exemplary embodiment; 
       FIG. 2  is a reversed, isometric view of the rocking key of  FIG. 1 ; 
       FIG. 3  is an isometric view of a portable computer, with the rocking key of  FIG. 1  being accommodated therein; 
       FIG. 4  is an exploded, isometric view of the portable computer of  FIG. 3 , with an electrical switch assembly employing the rocking key and a baseboard being remained thereof; 
       FIG. 5  is an assembled, isometric view of the electrical switch assembly and the baseboard of  FIG. 4 ; 
       FIG. 6  is a cross-sectional view of the assembly of the electrical switch assembly and the baseboard of  FIG. 5 , taken along line VI—VI; and 
       FIG. 7  is an isometric view of a rocking key of an electrical switch in accordance with a second exemplary embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following embodiments, a portable computer is used as an example for illustration. It is noted that electronic apparatuses in these embodiments may be portable computers, mobile phones or any other electronic apparatuses. 
   Referring to  FIGS. 1 and 2 , a rocking key  20  includes a keycap  22  and a pair of supporting arms  24  arranged at two opposite sides of the keycap  22 . The keycap  22  includes a flange  220 , a pair of posts  224 , a rib portion  226 , and a pair of trunnions  228 . A recess portion  222  is defined in the keycap  22 . On a top of the keycap  22 , two opposite end portions  230  are depressible, and a center portion  232  interconnects the two end portions  230 . 
   The flange  220  is formed around and extends out from a periphery of the recess portion  222 . The pair of posts  224  perpendicularly extend from a first bottom  222   a  of the recess portion  222 . The rib portion  226  perpendicularly extends from the first bottom  222   a  of the recess portion  222  as well. The rib portion  226  is constructed as a board shape. The pair of posts  224  are symmetrically arranged at two opposite sides of the rib portion  226 . A height of the rib portion  226  is larger than that of each post  224 . The pair of trunnions  228  perpendicularly extend from the flange  220 , and are arranged along a longitudinal direction of the rib portion  226 . A height from the first bottom  222   a  to a second bottom  228   a  of each trunnion  228  is larger than or equal to that of the rib portion  226 . 
   The pair of supporting arms  24  oppositely extend from opposite sides of the flange  20 , along the longitudinal direction of the rib portion  226 . Each supporting arm  24  is flexible, and includes a fixed end  240  attached to the flange  20 , a free end  242  and a washer  244  are integrally formed under the free end  242 . A first fixing hole  246  is defined through the free end  242  and the washer  244 . A longitudinal slot  248  is defined in each supporting arm  24  from the fixed end  240  to a circumference of the washer  244 . Each supporting arm  24  is thus partially divided into two spring portions  249  to improve its flexibility and restorability performance when being bent. 
   Referring also to  FIGS. 3 to 6 , a portable computer  40  employing at least one rocking key  20  is illustrated. The portable computer  40  includes a main body  42  and a display unit  44  pivoted to the main body  42 . The main body  42  includes a housing  45 , a switch assembly  46  and a baseboard  48 . The switch assembly  46  is accommodated in the housing  45  and includes at least one rocking key  20 , a circuit board  460 , and a pair of switches  462  mounted on the circuit board  460 . The keycap  22  partially passes through a hole  450  defined in the housing  45 , and the flange  220  of the rocking key  20  is blocked by the housing  45 . A top portion of the keycap  22  is exposed out of the housing  45 . A pair of fixing slots  464  are defined in the circuit board  460  and each corresponds to the first fixing holes  246 . The switches  462  each corresponds to the pair of the post  224 . The baseboard  48  defines a pair of second fixing holes  480  corresponding to the first fixing holes  246 . A pair of bolts (not shown) are correspondingly and sequentially screwed through the first fixing holes  246 , the fixing slots  464 , and the second fixing holes  480  so as to secure the rocking key  20  and the switch  46  to the baseboard  48 . The supporting arms  24  are deformable because they are flexible. The keycap  22  is rotatably supported by the pair of trunnions  228  and the supporting arms  24 . 
   When a user presses one end portion  230  of the keycap  22 , the pair of supporting arms  24  are deformed, and thus the keycap  22  rotates around a line L—L connecting the pair of trunnions  228 . Once the post  224  presses the corresponding switch  462 , a circuit (not shown) is activated. During this process, another opposite post  224  is separated from its corresponding switch  462 . When the user accidentally presses the center portion  232  of the keycap  22 , the keycap  22  does not move downward or moves slightly downward because of the support of the rib portion  226 . Therefore, potential, adverse affects to a reliability of the electrical switch assembly may be avoided because the two posts  224  cannot be simultaneously in contact with the corresponding switches  462 . 
   Referring to  FIG. 7 , a rocking key  60  in accordance with a second embodiment is illustrated. The rocking key  60  includes a keycap  62  and a pair of supporting arms  64 . The keycap  62  includes a pair of posts  624 , and a rib portion  626 . A recess portion  622  is defined in the keycap  62 . The pair of posts  624  and the rib portion  626  perpendicularly extend from a bottom of the recess portion  622 . The pair of posts  624  are symmetrically arranged at two opposite sides of the rib portion  626 . The supporting arms  64  are also symmetrically arranged at two opposite sides of the rib portion  626 . A height of the rib portion  626  is larger than that of each post  624 . The rib portion  626  is high enough to prevent the two posts  624  from being depressed down at the same time. The rib portion  626  also acts as a shaft around which the keycap  62  can rotate. 
   In alternative embodiments, the number of the posts  224  is not limited to two; three or more posts may be applied in the recess portion  222 . The number of the supporting arms  24  is also not limited to two; three or more supporting arms may be used. The flange  220  may be omitted if the fixed ends  240  of the supporting arms  24  are attached to the periphery of the keycap  20 . 
   The embodiments described herein are merely illustrative of the principles of the present invention. Other arrangements and advantages may be devised by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the present invention should be deemed not to be limited to the above detailed description, but rather by the spirit and scope of the claims that follow, and their equivalents.