Abstract:
A key structure and a keyboard including multiple key structures are provided. The key structure includes a keycap, a base plate and a scissors-type support member between the keycap and the base plate. The scissors-type support member includes an inner frame having a convex part and an outer frame having a V-shaped notch. The convex part is received in the V-shaped notch. By controlling relative positions between the convex part and the V-shaped notch, the keycap is stably moved in the vertical direction.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a key structure, and more particularly to a key structure for use in a keyboard. 
     BACKGROUND OF THE INVENTION 
     A keyboard is a widely-used input device of a computer. Generally, a keyboard has a plurality of key structures. Referring to  FIG. 1 , a schematic perspective view of a key structure  1  of the keyboard is illustrated. When the key structure  1  is depressed, a corresponding switch is triggered to generate an electronic signal to the computer. 
       FIG. 2  is a schematic exploded view illustrating a key structure according to the prior art. As shown in  FIG. 2 , the key structure  1  principally comprises a keycap  11 , a scissors-type support member, an elastic element  14 , a membrane switch  15  and a base plate  16 . The scissors-type support member comprises an inner frame  12  and an outer frame  13 . The inner frame  12  and the outer frame  13  cooperate with each other to fix the keycap  11  on the base plate  16 . The membrane switch  15  is arranged on the base plate  16 . The elastic element  14  is arranged between the keycap  11  and the membrane switch  15 . When the keycap  11  is depressed, the elastic element  14  is deformed downwardly to trigger the membrane switch  15  such that the membrane switch  15  generates an electronic signal. 
     In designing the scissors-type support member, the keycap  11  needs to be returned to its original position after the depressing force exerted on the keycap  11  is eliminated. Generally, the elastic element  14  provides the restoring force to push the keycap  11  back to its original position. Moreover, the inner frame  12  and the outer frame  13  should cooperate with each other in order to precisely control the vertical moving action of the keycap  11 . In other words, the configurations of the inner frame  12  and the outer frame  13  are very important factors that influence the quality and the use life of the key structure  1 . 
     Please refer to  FIG. 2  again. Two pivot rods  121  are formed on the arm part of the inner frame  12 . Corresponding to the pivot rods  121 , two pivot holes  131  are formed on an arm part of the outer frame  13 . The pivot rods  121  are pivotally coupled with the pivot holes  131  such that the inner frame  12  is rotatable on the outer frame  13 . For combining the inner frame  12  with the outer frame  13 , the technician needs to prop open the arm part of the outer frame  13  to widen the distance between these two pivot holes  131 . As such, the pivot rods  121  can be successfully inserted into corresponding pivot holes  131  so as to combine the inner frame  12  and the outer frame  13  together. The process of propping open the outer frame  13  is time-consuming and thus detrimental to the throughput of the keyboard. On the other hand, if the external force used to prop open the outer frame  13  is improper, the outer frame  13  is readily damaged and the yield is reduced. 
     Please refer to  FIG. 2  again. After the inner frame  12  and the outer frame  13  of the conventional key structure  1  are combined together, the pivot rods  121  are pivotally coupled with the pivot holes  131 . For maintaining stability of the keycap  11  and preventing from rocking the keycap  11  during the keycap  11  is depressed or returned to its original position, the pivot rods  121  need to be tightly fitted into corresponding pivot holes  131 . Since the pivot rods  121  are tightly fitted into corresponding pivot holes  131 , a strong friction force is generated when the inner frame  12  is rotated with respect to the outer frame  13 . Under this circumstance, the tactile feel upon depressing the keycap  11  is deteriorated. After the keycap  11  has been depressed for many times, the regions between the pivot rods  121  of the inner frame  12  and the pivot holes  131  of the outer frame  13  are readily abraded by the friction force. That is, the pivot rods  121  will no longer be tightly fitted into corresponding pivot holes  131 . Finally, the keycap  11  is unstable and easily rocked. 
     Therefore, there is a need of providing a scissors-type support member capable of maintaining stable movement of the keycap and achieving a desired tactile feel when the keycap is depressed. Moreover, the inner frame and the outer frame of the scissors-type support member should be easily assembled without the need of propping open the outer frame. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a key structure whose scissors-type support member can keep stable movement of the keycap and achieve a desired tactile feel when the keycap is depressed. 
     Another object of the present invention provides a key structure whose scissors-type support member is easily assembled. 
     In accordance with an aspect of the present invention, there is provided a key structure. The key structure includes a keycap, a base plate and a scissors-type support member. The scissors-type support member is used for connecting the keycap with the base plate. The scissors-type support member includes an inner frame and an outer frame. The inner frame has a first convex part and an internal concave part formed on an arm part of the inner frame. The first convex part includes a first inclined surface and a second inclined surface. The outer frame has an internal V-shaped notch and a second convex part formed on an arm part of the outer frame. The V-shaped notch includes a third inclined surface and a fourth inclined surface. When the keycap is located at a first height with respect to the base plate, the first inclined surface is sustained against the third inclined surface. When the keycap is located at a second height with respect to the base plate, the second inclined surface is sustained against the fourth inclined surface. 
     In an embodiment, the second convex part is a triangular prism having a fifth inclined surface extended from the third inclined surface, the concave part has a sixth inclined surface, and the triangular prism is accommodate in the concave part, wherein the fifth inclined surface is sustained against the sixth inclined surface when the keycap is located at the first height. 
     In an embodiment, the triangular prism has a first bottom surface and the concave part has a second bottom surface, wherein the first bottom surface is sustained against the second bottom surface when the keycap is located at the second height. 
     In an embodiment, the key structure further includes a membrane switch and an elastic element. The membrane switch is arranged on the base plate. The elastic element is arranged between the keycap and the membrane switch. The membrane switch is triggered by the elastic element when the keycap is depressed to be located from the first height to the second height. 
     In an embodiment, a first connecting part and a guiding slot are formed on a bottom of the keycap, a hook and a second connecting part are formed on the base plate, a first coupling shaft and a first glide shaft are formed on both terminals of the arm part of the inner frame, and a second coupling shaft and a second glide shaft are formed on both terminals of the arm part of the outer frame. Via the engagement between the hook and the first glide shaft and the engagement between the second coupling shaft and the second connecting part, the scissors-type support member is fixed on the base plate. Via the engagement between the guiding slot and the second glide shaft and the engagement between the first connecting part and the first coupling shaft, the keycap is combined with the scissors-type support member. 
     In accordance with another aspect of the present invention, there is provided a keyboard. The keyboard includes multiple keycaps, a base plate, multiple scissors-type support members, multiple membrane switches and multiple elastic elements. The scissors-type support members are used for connecting the keycaps with the base plate. Each of the scissors-type support members includes an inner frame and an outer frame. The inner frame has a first convex part and an internal concave part formed on an arm part of the inner frame. The first convex part includes a first inclined surface and a second inclined surface. The outer frame has an internal V-shaped notch and a second convex part formed on an arm part of the outer frame. The V-shaped notch includes a third inclined surface and a fourth inclined surface. When the keycap is located at a first height with respect to the base plate, the first inclined surface is sustained against the third inclined surface. When the keycap is located at a second height with respect to the base plate, the second inclined surface is sustained against the fourth inclined surface. The membrane switches are arranged on the base plate. The elastic elements are arranged between respective keycaps and respective membrane switches. The membrane switches are triggered by the elastic elements when corresponding keycaps are depressed to be located from the first height to the second height. 
     In an embodiment, the second convex part is a triangular prism having a fifth inclined surface extended from the third inclined surface, the concave part has a sixth inclined surface, and the triangular prism is accommodate in the concave part, wherein the fifth inclined surface is sustained against the sixth inclined surface when the keycap is located at the first height. 
     In an embodiment, the triangular prism has a first bottom surface and the concave part has a second bottom surface, wherein the first bottom surface is sustained against the second bottom surface when the keycap is located at the second height. 
     In an embodiment, the key structure further includes a membrane switch and an elastic element. The membrane switch is arranged on the base plate. The elastic element is arranged between the keycap and the membrane switch. The membrane switch is triggered by the elastic element when the keycap is depressed to be located from the first height to the second height. 
     In an embodiment, a first connecting part and a guiding slot are formed on a bottom of the keycap, a hook and a second connecting part are formed on the base plate, a first coupling shaft and a first glide shaft are formed on both terminals of the arm part of the inner frame, and a second coupling shaft and a second glide shaft are formed on both terminals of the arm part of the outer frame. Via the engagement between the hook and the first glide shaft and the engagement between the second coupling shaft and the second connecting part, the scissors-type support member is fixed on the base plate. Via the engagement between the guiding slot and the second glide shaft and the engagement between the first connecting part and the first coupling shaft, the keycap is combined with the scissors-type support member. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view illustrating a key structure of a keyboard according to the prior art; 
         FIG. 2  is a schematic exploded view illustrating a key structure according to the prior art; 
         FIG. 3  is a schematic exploded view illustrating a key structure according to a preferred embodiment of the present invention; 
         FIG. 4A  is a schematic perspective view illustrating the keycap of the key structure according to the preferred embodiment of the present invention; 
         FIG. 4B  is a schematic perspective view illustrating the inner frame of the key structure according to the preferred embodiment of the present invention; 
         FIG. 4C  is a schematic perspective view illustrating the inner frame of the outer frame according to the preferred embodiment of the present invention; 
         FIGS. 5A ,  5 B and  5 C schematically illustrate a process of assembling the inner frame and the outer frame of the scissors-type support member of the key structure according to the preferred embodiment of the present invention; 
         FIG. 6A  is a schematic cross-sectional view illustrating the key structure of the present invention that is not depressed; and 
         FIG. 6B  is a schematic cross-sectional view illustrating the key structure of the present invention that has been depressed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 3  is a schematic exploded view illustrating a key structure according to a preferred embodiment of the present invention. As shown in  FIG. 3 , the key structure  2  comprises a keycap  21 , a scissors-type support member, an elastic element  24 , a membrane switch  25  and a base plate  26 . The scissors-type support member comprises an inner frame  22  and an outer frame  23 , which cooperate with each other to fix the keycap  21  on the base plate  26 . The membrane switch  25  is arranged on the base plate  26 . The elastic element  24  is arranged between the keycap  21  and the membrane switch  25 . When the keycap  21  is depressed, the elastic element  24  is deformed downwardly to trigger the membrane switch  25  such that the membrane switch  25  generates an electronic signal. By means of the elastic element  24 , the keycap  21  can be returned to its original position where the keycap  21  is not depressed. Moreover, the base plate  26  has a hook  261  and a second connecting part  262 . The second connecting part  262  comprises a hook  262 A and a stopper  262 B. 
       FIGS. 4A ,  4 B and  4 C are schematic perspective views illustrating the keycap  21 , the inner frame  22  and the outer frame  23  of the key structure  2  according to the preferred embodiment of the present invention, respectively. Hereinafter, the configurations of the key structure  2  will be illustrated in more details with reference to  FIGS. 4A ,  4 B and  4 C. 
     As shown in  FIG. 4A , a first connecting part  211  and a guiding slot  212  are formed on the bottom of the keycap  21 . As shown in  FIG. 4B , a first convex part  222  and an internal concave part  223  are formed on an arm part  221  of the inner frame  22 . The first convex part  222  has a first inclined surface  222 A and a second inclined surface  222 B. The concave part  223  has a second bottom surface  223 A and a sixth inclined surface  223 B. The sixth inclined surface  223 B is extended from the first inclined surface  222 A. In addition, a first coupling shaft  224  and a first glide shaft  225  are formed on both terminals of the arm part  221  of the inner frame  22 . As shown in  FIG. 4C , an internal V-shaped notch  232  and a second convex part  233  are formed on an arm part  231  of the outer frame  23 . The V-shaped notch  232  comprises a third inclined surface  232 B and a fourth inclined surface  232 A. In this embodiment, the second convex part  233  is a triangular prism. The second convex part  233  comprises a first bottom surface  233 A and a fifth inclined surface  233 B. The fifth inclined surface  233 B is extended from the third inclined surface  232 B. In addition, a second coupling shaft  234  and a second glide shaft  235  are formed on both terminals of the arm part  231  of the outer frame  23 . 
     Hereinafter, the process of assembling the inner frame and the outer frame of the scissors-type support member of the key structure will be illustrated with reference to  FIGS. 5A ,  5 B and  5 C. For assembling inner frame  22  and the outer frame  23  of the scissors-type support member, the inner frame  22  is firstly inserted into the outer frame  23  and then the inner frame  22  is turned over. As shown in  FIG. 5A  and  FIG. 5B , the first inclined surface  222 A of the first convex part  222  of the inner frame  22  is aslant inserted into the V-shaped notch  232  of the outer frame  23  such that the first inclined surface  222 A is sustained against the fourth inclined surface  232 A of the V-shaped notch  232  of the outer frame  23  (see  FIG. 5B ). Meanwhile, the concave part  223  of the inner frame  22  faces the outer frame  23 . Next, as shown in  FIG. 5B  and  FIG. 5C , the inner frame  22  is turned over in the direction indicated as the arrow R. After the second convex part  233  of the outer frame  23  is engaged with the concave part  223  of the inner frame  22 , the scissors-type support member of the key structure  2  is assembled. 
     In this embodiment, the scissors-type support member is very easily assembled by combining the first convex part  222  and the internal concave part  223  of the inner frame  22  with the V-shaped notch  232  and the second convex part  233  of the outer frame  23 . Since the user needs not to prop open the outer frame  23  during the process of assembling the scissors-type support member, the possibility of damaging the outer frame  23  is minimized. In particular, it is very simple to assemble the scissors-type support member of the present invention by aslant inserting the inner frame  22  into the outer frame  23  and turning over the inner frame  22 . That is, the process of assembling the scissors-type support member of the present invention may be automated and thus the throughput of the key structure or the keyboard is enhanced. 
     After the scissors-type support member is assembled, the scissors-type support member is fixed on the base plate  26  via the engagement between the hook  261  and the first glide shaft  225  and the engagement between the second coupling shaft  234  and the second connecting part  262 . Next, via the engagement between the guiding slot  212  and the second glide shaft  235  and the engagement between the first connecting part  211  and the first coupling shaft  224 , the keycap  21  is combined with the scissors-type support member. 
       FIG. 6A  is a schematic cross-sectional view illustrating the key structure of the present invention that is not depressed.  FIG. 6B  is a schematic cross-sectional view illustrating the key structure of the present invention that has been depressed. The use of the scissors-type support member to balance the keycap  21  and achieve a desired tactile feel when the keycap  21  is depressed will be illustrated with reference to  FIG. 6A  and  FIG. 6B . 
     In a case that the keycap  21  is not depressed, the keycap  21  is located at a first height Hi with respect to the bottom of the base plate  26 . As shown in  FIG. 6A , the first inclined surface  222 A of the first convex part  222  of the inner frame  22  is sustained against the third inclined surface  232 B of the V-shaped notch  232  of the outer frame  23 . At this moment, the fifth inclined surface  233 B of the second convex part  233  of the outer frame  23  is also sustained against the sixth inclined surface  223 B of the concave part  223  of the inner frame  22 . Whereas, when the keycap  21  is depressed, the height of the keycap  21  with respect to the bottom of the base plate  26  is lowered from the first height H 1  to a second height H 2 . As shown in  FIG. 6B , the second inclined surface  222 B of the first convex part  222  of the inner frame  22  is sustained against the fourth inclined surface  232 A of the V-shaped notch  232  of the outer frame  23 . At this moment, the first bottom surface  233 A of the second convex part (i.e. the triangular prism)  233  of the outer frame  23  is engaged with the second bottom surface  223 A of the concave part  223  of the inner frame  22 . 
     From the above description, since the inner frame  22  and the outer frame  23  are contacted with each other by a surface-to-surface contacting manner during the keycap  21  is vertically moved, the scissors-type support member of the present invention is more stable and the rocking phenomenon is minimized. The surface-to-surface contacting manner increases the contact area between the inner frame  22  and the outer frame  23 , and thus the stability of the scissors-type support member is enhanced. Moreover, since the inner frame  22  is not pivotally coupled with the outer frame  23 , the first convex part  222  of the inner frame  22  is nearly not contacted with the V-shaped notch  232  of the outer frame  23  during the keycap  21  is moved from the first height H 1  to the second height H 2  or from the second height H 2  to the first height H 1 . As a consequence, the abrasion of the scissors-type support member is reduced and the use life of the keycap is extended. Moreover, due to the scissors-type support member of the present invention, a desired tactile feel when the keycap is depressed will be achieved. 
     For further reducing the abrasion between the inner frame  22  and the outer frame  23  and facilitating assembling the scissors-type support member, the scissors-type support member of the key structures  2  can be further modified. For example, fillets are optionally formed at the surface-to-surface joints of the first convex part  222  and the concave part  223  of the inner frame  22  and the V-shaped notch  232  and the second convex part  233  of the outer frame  23 . In other words, fillets can be formed at the joints between the first inclined surface  222 A and the second inclined surface  222 B of the first convex part  222  of the inner frame  22 , between the third inclined surface  232 B and the fourth inclined surface  232 A of the V-shaped notch  232  of the outer frame  23  and/or between the first bottom surface  233 A and the fifth inclined surface  233 B of the second convex part  233  of the outer frame  23 . 
     The key structure  2  of the present invention can be applied to a keyboard. That is, the keyboard has multiple key structures  2  of the present invention. An example of the keyboard includes but is not limited to a desktop keyboard or a notebook keyboard. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.