Patent Publication Number: US-11646167-B1

Title: Keyboard device and key structure thereof

Description:
FIELD OF THE INVENTION 
     The present invention relates to an input device, and more particularly to a keyboard device and a key structure of the keyboard device. 
     BACKGROUND OF THE INVENTION 
     With increasing development of science and technology, a variety of electronic devices are designed in views of convenience and user-friendliness. For helping the users well operate the electronic devices, the electronic devices are gradually developed in views of humanization. The input devices of the common electronic devices include for example mouse devices, keyboard devices, trackball devices, or the like. Via the keyboard device, texts or symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboard devices. 
     Generally, a keyboard device comprises plural key structures. Each key structure comprises a keycap, a scissors-type connecting member, a membrane circuit board and a base plate. These components are stacked on each other sequentially. In case that the keyboard device is a luminous keyboard device, the keyboard device is equipped with a backlight module under the base plate. 
     Moreover, a membrane switch is installed on the membrane circuit board, and an elastic element (e.g., a rubber dome) is arranged between the keycap and the membrane circuit board. The scissors-type connecting member is connected between the keycap and the base plate. Moreover, the scissors-type connecting member comprises a first frame and a second frame. The second frame is pivotally coupled to the first frame. Consequently, the first frame and the second frame can be swung relative to each other. 
     While the keycap of any key structure is pressed down and moved downwardly relative to the base plate, the first frame and the second frame of the scissors-type connecting member are switched from an open-scissors state to a stacked state. Moreover, as the keycap is moved downwardly to compress the elastic element, the corresponding membrane switch is pushed and triggered by the elastic element. Consequently, the keyboard device generates a corresponding key signal. 
     When the keycap of the key structure is no longer pressed, the keycap is moved upwardly relative to the base plate in response to an elastic force of the elastic element. Meanwhile, the first frame and the second frame are switched from the stacked state to the open-scissors state, and the keycap is returned to its original position. 
     However, even if the rubber-dome elastic element is not compressed, the rubber-dome elastic element has a bulky volume. In case that the key structure of the keyboard is equipped with the rubber-dome elastic element, the production of the keyboard is limited by the material of the component. Under this circumstance, it is difficult to reduce the overall volume of the key structure or fabricate the slim-type keyboard. 
     For solving the above drawbacks, a metal-dome elastic element is used as a restoring mechanism. The metal-dome elastic element is made of stainless steel or copper. In comparison with the rubber-dome elastic element, the volume or thickness of the metal-dome elastic element is reduced. Consequently, the overall volume of the key structure is reduced, and the keyboard device is slim. 
     Although the volume or thickness of the metal-dome elastic element is reduced, some drawbacks occur. For example, when the metal-dome elastic element is compressed by the keycap, the travel distance is very short. Consequently, the tactile feel of depressing the metal-dome elastic element is usually unsatisfied to the user. 
     Therefore, there is a need of providing an improved keyboard device and an associated key structure in order to overcome the drawbacks of the conventional technologies. 
     SUMMARY OF THE INVENTION 
     The present invention provides a keyboard device and a key structure with enhanced operating feel. 
     The other objects and advantages of the present invention will be understood from the disclosed technical features. 
     In accordance with an aspect of the present invention, a keyboard device is provided. The keyboard device includes plural key structures. Each of the plural key structures includes a base plate, a keycap, a membrane circuit board, a connecting member and an elastic element. The keycap is located over the base plate. The keycap includes a pressing post. The pressing post is protruded in a direction toward the base plate. The membrane circuit board is arranged between the base plate and the keycap. The connecting member is penetrated through the membrane circuit board and connected between the keycap and the base plate. The keycap is movable upwardly or downwardly relative to the membrane circuit board through the connecting member. The elastic element is arranged between the keycap and the membrane circuit board. The elastic element includes a resilience piece and plural supporting ribs. The plural supporting ribs are arranged between the resilience piece and the keycap. The plural supporting ribs are protruded in a direction toward the keycap and contacted with the pressing post of the keycap. Consequently, there is a gap between the pressing post and the resilience piece. 
     In an embodiment, while the keycap is pressed down in response to an external force, the pressing post is moved downwardly to push the plural supporting ribs of the elastic element, and the plural supporting ribs are subjected to deformation. Consequently, the keycap is moved toward the membrane circuit board and moved from a first position to a second position. 
     In an embodiment, as the keycap is continuously pressed in response to the external force, the resilience piece of the elastic element is continuously pushed by the pressing post, and the resilience piece is subjected to deformation. Consequently, the keycap is moved toward the membrane circuit board and moved from the second position to a third position. 
     In an embodiment, the plural supporting ribs of the elastic element include two supporting ribs, and the two supporting ribs are located at two opposite sides of the resilience piece. 
     In an embodiment, the plural supporting ribs of the elastic element include four supporting ribs. The four supporting ribs face each other in pairs. The four supporting ribs are discretely arranged on edges of the resilience piece. 
     In an embodiment, each of the plural supporting ribs of the elastic element includes a supporting part and a carrying part. The supporting part is connected between the resilience piece and the carrying part. The carrying part is arranged between the pressing post of the keycap and the resilience piece. The pressing post of the keycap is carried by the carrying part. 
     In an embodiment, the plural supporting ribs of the elastic element are integrally formed with the resilience piece, and each of the plural supporting ribs are bent upwardly from a portion of the resilience piece. 
     In an embodiment, the resilience piece of the elastic element has a semi-spheric shell structure, and the semi-spheric shell structure has a cavity facing the membrane circuit board. 
     In an embodiment, the keycap includes a top wall and a skirt part. The skirt part is protruded from a periphery region of the top wall in a direction toward the membrane circuit board. The pressing post of the keycap is installed on an inner surface of the top wall. 
     In an embodiment, the key structure further includes a stabilizer bar, and the stabilizer bar includes a transverse bar part and two locking parts. The two locking parts are respectively located at two ends of the transverse bar part. The transverse bar part is pivotally coupled to the keycap. The two locking parts are connected with the base plate. 
     In accordance with another aspect of the present invention, a key structure is provided. The key structure includes a base plate, a keycap, a membrane circuit board, a connecting member and an elastic element. The keycap is located over the base plate. The keycap includes a pressing post. The pressing post is protruded in a direction toward the base plate. The membrane circuit board is arranged between the base plate and the keycap. The connecting member is penetrated through the membrane circuit board and connected between the keycap and the base plate. The keycap is movable upwardly or downwardly relative to the membrane circuit board through the connecting member. The elastic element is arranged between the keycap and the membrane circuit board. The elastic element includes a resilience piece and plural supporting ribs. The plural supporting ribs are arranged between the resilience piece and the keycap. The plural supporting ribs are protruded in a direction toward the keycap and contacted with the pressing post of the keycap. Consequently, there is a gap between the pressing post and the resilience piece. 
     From the above descriptions, the present invention provides the keyboard device. The elastic element of each key structure is equipped with plural supporting ribs for supporting the keycap. Consequently, the travel distance of moving the keycap in the direction toward the membrane circuit board is increased. Moreover, while the keycap is moved downwardly, an empty travel distance is generated to provide a buffering effect. Consequently, the tactile feel of depressing the key structure is satisfactory to the user. In comparison with the conventional technology of using the elastic element with small volume or thickness, the tactile feel of operating the key structure of the present invention is enhanced. 
     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 top view illustrating the outer appearance of a keyboard device according to an embodiment of the present invention; 
         FIG.  2    is a schematic perspective view illustrating a portion of a key structure of the keyboard device as shown in  FIG.  1   ; 
         FIG.  3    is a schematic exploded view illustrating the key structure as shown in  FIG.  2    and taken along a viewpoint; 
         FIG.  4    is a schematic exploded view illustrating the key structure as shown in  FIG.  2    and taken along another viewpoint; 
         FIG.  5    is a schematic perspective view illustrating the elastic element of the key structure as shown in  FIGS.  3  and  4   ; and 
         FIG.  6    is a schematic cross-sectional view illustrating the key structure as shown in  FIG.  2    and taken along the line AA. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please refer to  FIGS.  1 ,  2 ,  3 ,  4 ,  5  and  6   .  FIG.  1    is a schematic top view illustrating the outer appearance of a keyboard device according to an embodiment of the present invention.  FIG.  2    is a schematic perspective view illustrating a portion of a key structure of the keyboard device as shown in  FIG.  1   .  FIG.  3    is a schematic exploded view illustrating the key structure as shown in  FIG.  2    and taken along a viewpoint.  FIG.  4    is a schematic exploded view illustrating the key structure as shown in  FIG.  2    and taken along another viewpoint.  FIG.  5    is a schematic perspective view illustrating the elastic element of the key structure as shown in  FIGS.  3  and  4   .  FIG.  6    is a schematic cross-sectional view illustrating the key structure as shown in  FIG.  2    and taken along the line AA. For succinctness, only a single key structure and associated components are shown in  FIGS.  2 ,  3 ,  4 ,  5  and  6   . 
     As shown in  FIG.  1   , the keyboard device  1  comprises plural key structures  10 . These key structures  10  are classified into some types, e.g., ordinary keys, numeric keys and function keys. When one of the key structures  10  is pressed down by the user&#39;s finger, the keyboard device  1  generates a corresponding key signal to a computer, and thus the computer executes a corresponding function. For example, when an ordinary key is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key is depressed, a corresponding number is inputted into the computer. In addition, the function keys (F1˜F12) can be programmed to provide various quick access functions. 
     The key structure  10  of the keyboard device  1  will be described in more details as follows. 
     Please refer to  FIGS.  2 ,  3 ,  4 ,  5  and  6   . In an embodiment, the key structure  10  comprises a base plate  101 , a keycap  102 , a membrane circuit board  103 , a connecting member  104  and an elastic element  105 . 
     The keycap  102  is located over the base plate  101 . The keycap  102  comprises a pressing post  1020 . The pressing post  1020  is protruded in the direction toward the base plate  101 . 
     The membrane circuit board  103  is arranged between the base plate  101  and the keycap  102 . 
     The connecting member  104  is penetrated through the membrane circuit board  103  and connected between the keycap  102  and the base plate  101 . Moreover, the keycap  102  is movable upwardly or downwardly relative to the membrane circuit board  103  through the connecting member  104 . 
     The elastic element  105  is arranged between the keycap  102  and the membrane circuit board  103 . In an embodiment, the elastic element  105  comprises a resilience piece  1051  and plural supporting ribs  1052 . These supporting ribs  1052  are arranged between the resilience piece  1051  and the keycap  102 . Each supporting rib  1052  is protruded in the direction toward the keycap  102  and contacted with the pressing post  1020  of the keycap  102 . Consequently, there is a gap G between the pressing post  1020  and the resilience piece  1051 . 
     Please refer to  FIGS.  2 ,  3 ,  4 ,  5  and  6    again. In an embodiment, the keycap  102  comprises a top wall  1021  and a skirt part  1022 . The skirt part  1022  of the keycap  102  is protruded from a periphery region of the top wall  1021  in the direction toward the membrane circuit board  103 . In an embodiment, the pressing post  1020  of the keycap  102  is installed on an inner surface of the top wall  1021  that faces the membrane circuit board  103 . In addition, the pressing post  1020  is disposed within an accommodation space that is defined by the top wall  1021  and the skirt part  1022  collaboratively. 
     Please refer to  FIGS.  3 ,  4  and  6    again. In an embodiment, the key structure  10  further comprises a stabilizer bar  106 . The stabilizer bar  106  comprises a transverse bar part  1061  and two locking parts  1062 . The two locking parts  1062  are located at two ends of the transverse bar part  1061 , respectively. The transverse bar part  1061  of the stabilizer bar  106  is pivotally coupled to the keycap  102 . The two locking parts  1062  of the stabilizer bar  106  are connected with the base plate  101 . 
     The base plate  101  comprises a first hook  1011  and a second hook  1012 . The first hook  1011  and the second hook  1012  are protruded upwardly and penetrated through the membrane circuit board  103 . The keycap  102  further comprises plural first pivotal parts  1023 . Particularly, the transverse bar part  1061  of the stabilizer bar  106  is pivotally coupled to the plural first pivotal parts  1023  of the keycap  102 . The two locking parts  1062  of the stabilizer bar  106  are respectively engaged with the first hook  1011  and the second hook  1012  of the base plate  101 . Consequently, the stabilizer bar  106  is connected between the keycap  102  and the base plate  101 . 
     Please refer to  FIGS.  3 ,  4  and  6    again. In an embodiment, the base plate  102  further comprises a third hook  1013  and a fourth hook  1014 . The connecting member  104  is connected with the base plate  101  through the third hook  1013  and the fourth hook  1014  of the base plate  101 . It is noted that the way of connecting the connecting member  104  with the base plate  101  is not restricted. Preferably but not exclusively, the keycap  102  comprises plural second pivotal parts  1024 . In addition, the connecting member  104  is pivotally coupled to the keycap  102  through the plural second pivotal parts  1024  of the keycap  102 . Preferably but not exclusively, the connecting member  104  is a scissors-type connecting member. The operations of the connecting member  104  are similar to those of the conventional technology, and not redundantly described herein. 
     Please refer to  FIGS.  3 ,  4  and  6    again. In an embodiment, the membrane circuit board  103  comprises plural openings  1030 . The number of the openings  1030  is not restricted. The connecting member  104  is penetrated through the corresponding openings  1030  and connected between the keycap  102  and the base plate  101 . Moreover, a membrane switch (not shown) is installed on the membrane circuit board  103 . While the keycap  102  is moved downwardly relative to the membrane circuit board  103  through the connecting member  104 , the elastic element  105  is pushed by the pressing post  1020  of the keycap  102  and subjected to deformation. Consequently, the membrane switch on the membrane circuit board  103  is triggered to generate a corresponding key signal. 
     Please refer to  FIGS.  3 ,  4 ,  5  and  6   . In an embodiment, each supporting rib  1052  of the elastic element  105  comprises a supporting part  10521  and a carrying part  10522 . The supporting part  10521  of the supporting rib  1052  is connected between the resilience piece  1051  and the carrying part  10522  of the supporting rib  1052 . The carrying part  10522  of the supporting rib  1052  is arranged between the pressing post  1020  of the keycap  102  and the resilience piece  1051 . The carrying part  10522  is used for supporting the pressing post  1020  of the keycap  102 . That is, when the key structure  10  is not pressed down, the pressing post  1020  of the keycap  102  is supported by the plural supporting ribs  1052 . Consequently, the gap G between the pressing post  1020  of the keycap  102  and the resilience piece  1051  of the elastic element  105  can be maintained. 
     In an embodiment, the supporting ribs  1052  and the resilience piece  1051  are integrally formed. For example, after the main portions of the supporting ribs  1052  are formed on the resilience piece  1051  by a stamping process and bent upwardly, the supporting ribs  1052  are formed. It is noted that the method of forming the supporting ribs  1052  is not restricted. For example, in another embodiment, the supporting ribs  1052  and the resilience piece  1051  are individual components. 
     In an embodiment, the resilience piece  1051  has a semi-spheric shell structure (e.g., a snap dome structure). When the resilience piece  1051  is subjected to deformation, the membrane switch on the membrane circuit board  103  is triggered and electrically conducted. Moreover, the semi-spheric shell structure of the resilience piece  1051  has a cavity  10510  facing the membrane circuit board  103 . When the resilience piece  1051  is subjected to deformation in response to the elastic force, the cavity  10510  provides a sufficient deformable space of the resilience piece  1051 . 
     Please refer to  FIG.  6   . When the keycap  102  is not pressed, the pressing post  1020  of the keycap  102  is carried by the carrying parts  10522  of the plural supporting ribs  1052  of the elastic element  105 . Consequently, there is the gap G between the pressing post  1020  of the keycap  102  and the resilience piece  1051  of the elastic element  105 , and the keycap  102  is positioned in a first position P 1 . 
     Please refer to  FIG.  6   . While the keycap  102  is pressed down in response to the external force, the pressing post  1020  of the keycap  102  is moved downwardly to push the plural supporting ribs  1052  of the elastic element  105 . After the plural supporting ribs  1052  of the elastic element  105  are pushed, the supporting parts  10521  and the carrying parts  10522  are all subjected to deformation and moved toward the resilience piece  1051  until these supporting ribs  1052  are contacted with the top surface of the resilience piece  1051 . While these supporting ribs  1052  are subjected to deformation, the keycap  102  is moved in the direction toward the membrane circuit board  103  and moved from the first position P 1  to a second position P 2 . Meanwhile, the membrane switch (not shown) on the membrane circuit board  103  has not been triggered. Since the path of moving the keycap  102  from the first position P 1  to the second position P 2  is an empty travel distance for providing a buffering effect, the tactile feel of pressing the keycap  102  is satisfactory to the user. 
     As the keycap  102  is continuously pressed in response to the external force, the resilience piece  1051  of the elastic element  105  is continuously pushed by the pressing post  1020  of the keycap  102 . After the resilience piece  1051  of the elastic element  105  is pushed, the resilience piece  1051  with the semi-spheric shell structure is subjected to inwardly concave deformation until the membrane switch (not shown) on the membrane circuit board  103  is triggered by the resilience piece  1051 . While the resilience piece  1051  with the semi-spheric shell structure is subjected to the inwardly concave deformation, the keycap  102  is moved in the direction toward the membrane circuit board  103  and moved from the second position P 2  to a third position P 3 . 
     In the above embodiment, the elastic element  105  comprises four supporting ribs  1052 . The four supporting ribs  1052  face each other in pairs. That is, the four supporting ribs are divided into two groups, and the two supporting ribs  1052  in each group face each other. Moreover, the four supporting ribs are discretely arranged on the edges of the resilience piece  1051 . It is noted that the number of the supporting ribs  1052  is not restricted. The number of the supporting ribs  1052  may be increased or decreased according to the practical requirements. For example, in case that the lighter tactile feel is required, only two supporting ribs  1052  installed on the resilience piece  1051  are feasible. That is, the two supporting ribs  1052  are installed on two opposite edges of the resilience piece  1051 . Whereas, in case that the heavier tactile feel is required, the number of the supporting ribs  1052  on the resilience piece  1051  may be increased to six. 
     From the above descriptions, the present invention provides the keyboard device. The elastic element of each key structure is equipped with plural supporting ribs for supporting the keycap. Consequently, the travel distance of moving the keycap in the direction toward the membrane circuit board is increased. Moreover, while the keycap is moved downwardly, an empty travel distance is generated to provide a buffering effect. Consequently, the tactile feel of depressing the key structure is satisfactory to the user. In comparison with the conventional technology of using the elastic element with small volume or thickness, the tactile feel of operating the key structure of the present invention is enhanced. 
     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 embodiments. 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.