Patent Publication Number: US-10312036-B2

Title: Keyboard device

Description:
FIELD OF THE INVENTION 
     The present invention relates to an input device, and more particularly to a keyboard device with plural key structures. 
     BACKGROUND OF THE INVENTION 
     Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard device, a trackball device, or the like. Via the keyboard device, characters or symbols can be directly inputted into the computer system. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboard devices. 
     Hereinafter, a key structure with a scissors-type connecting element in a conventional keyboard will be illustrated with reference to  FIG. 1 .  FIG. 1  is a schematic side cross-sectional view illustrating a conventional key structure. As shown in  FIG. 1 , the conventional key structure  1  comprises a keycap  11 , a scissors-type connecting element  12 , a rubbery elastomer  13 , a membrane switch circuit member  14  and a base plate  15 . The keycap  11 , the scissors-type connecting element  12 , the rubbery elastomer  13  and the membrane switch circuit member  14  are supported by the base plate  15 . The scissors-type connecting element  12  is used for connecting the base plate  15  and the keycap  11 . 
     The scissors-type connecting element  12  is arranged between the base plate  15  and the keycap  11 , and the base plate  15  and the keycap  11  are connected with each other through the scissors-type connecting element  12 . The scissors-type connecting element  12  comprises a first frame  121  and a second frame  122 . A first end of the first frame  121  is connected with the keycap  11 . A second end of the first frame  121  is connected with the base plate  15 . The rubbery elastomer  13  is enclosed by the scissors-type connecting element  12 . The membrane switch circuit member  14  comprises plural key intersections (not shown). When one of the plural key intersections is triggered, a corresponding key signal is generated. The rubbery elastomer  13  is disposed on the membrane switch circuit member  14 . Each rubbery elastomer  13  is aligned with a corresponding key intersection. When the rubbery elastomer  13  is depressed, the rubbery elastomer  13  is subjected to deformation to push the corresponding key intersection of the membrane switch circuit member  14 . Consequently, the corresponding key signal is generated. 
     The operations of the conventional key structure  1  in response to the depressing action of the user will be illustrated as follows. Please refer to  FIG. 1  again. When the keycap  11  is depressed, the keycap  11  is moved downwardly to push the scissors-type connecting element  12  in response to the depressing force. As the keycap  11  is moved downwardly relative to the base plate  15 , the keycap  11  pushes the corresponding rubbery elastomer  13 . At the same time, the rubbery elastomer  13  is subjected to deformation to push the membrane switch circuit member  14  and trigger the corresponding key intersection of the membrane switch circuit member  14 . Consequently, the membrane switch circuit member  14  generates a corresponding key signal. When the keycap  11  is no longer depressed by the user, no external force is applied to the keycap  11  and the rubbery elastomer  13  is no longer pushed by the keycap  11 . In response to the elasticity of the rubbery elastomer  13 , the rubbery elastomer  13  is restored to its original shape to provide an upward elastic restoring force. Consequently, the keycap  11  is returned to its original position where it is not depressed. 
     Generally, if the foreign liquid is introduced into the key structure, the membrane switch circuit member is possibly in a short-circuited state. For solving this problem, the membrane switch circuit member is designed to be a sealed structure with a waterproof function. Since the inner space of the sealed membrane switch circuit member contains gas, the inner gas is subjected to expansion or contraction in response to the temperature change. When the temperature increases, the volume of the inner gas expands. Consequently, it is difficult to make electric conduction of the key intersection of the membrane switch circuit member. When the temperature decreases, the volume of the inner gas contracts. Meanwhile, it is easy to make electric conduction of the key intersection of the membrane switch circuit member. However, the keyboard device is possibly suffered from an error operation. For easing the electric conduction of the membrane switch circuit member, the membrane switch circuit member membrane switch circuit member is equipped with a gas-escaping channel to escape the gas from the membrane switch circuit member. Due to the arrangement of the gas-escaping channel, the membrane switch circuit member is not the sealed structure. Under this circumstance, the waterproof efficacy is deteriorated. 
     Therefore, there is a need of providing a keyboard device with a waterproof function and capable of avoiding error operation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a keyboard device with a waterproof function and capable of avoiding error operation. 
     In accordance with an aspect of the present invention, there is provided a keyboard device. The keyboard device includes plural key structures, a switch circuit board, an elastic cover and a seal element. The plural key structures are exposed outside the keyboard device. The switch circuit board is located under the plural key structures. When the switch circuit board is triggered by one of the plural key structures, a corresponding key signal is generated. The switch circuit board includes a hollow region. The elastic cover is disposed on the switch circuit board. The hollow region is covered by the elastic cover, so that a foreign liquid is prevented from entering the switch circuit board. The seal element is disposed on sidewalls of the switch circuit board. Consequently, a sealed region is formed between the switch circuit board and the elastic cover to prevent the foreign liquid from entering the switch circuit board. When a volume of an inner gas within the sealed region increases, the elastic cover is subjected to expansion in response to elasticity of the elastic cover and the volume of the inner gas. When the volume of the inner gas within the sealed region decreases, the elastic cover is subjected to contraction in response to elasticity of the elastic cover and the volume of the inner gas. 
     From the above descriptions, the present invention provides the keyboard device. The elastic cover is disposed on the switch circuit board. Since no gas-escaping channel is installed in the switch circuit board, the sealed region in the switch circuit board can be maintained. Consequently, the keyboard device of the present invention has the waterproof function. When the temperature is changed and the inner gas within the switch circuit board is correspondingly changed, the elastic cover is subjected to expansion or contraction in response to the volume change of the inner gas and the elasticity of the elastic cover. Consequently, the distance between the first contact and the second contact of the switch circuit board can be maintained. In other words, the electric connection between the first contact and the second contact is established more easily and the problem of causing the erroneous operation is overcome. 
     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 side cross-sectional view illustrating a conventional key structure; 
         FIG. 2  is a schematic top view illustrating the outer appearance of a keyboard device according to a first embodiment of the present invention 
         FIG. 3  is a schematic exploded view illustrating a portion of the keyboard device according to the first embodiment of the present invention; 
         FIG. 4  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the first embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the first embodiment of the present invention, in which the elastic cover is subjected to expansion; 
         FIG. 6  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the first embodiment of the present invention, in which the elastic cover is subjected to contraction; 
         FIG. 7  is a schematic cross-sectional side view illustrating a portion of a keyboard device according to a second embodiment of the present invention; 
         FIG. 8  is a schematic cross-sectional side view illustrating a portion of a keyboard device according to a third embodiment of the present invention; and 
         FIG. 9  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the third embodiment of the present invention, in which the elastic cover is subjected to expansion. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For solving the drawbacks of the conventional technologies, the present invention provides a keyboard device. 
     Hereinafter, the structure of a keyboard device of the present invention will be described with reference to  FIG. 2 .  FIG. 2  is a schematic top view illustrating the outer appearance of a keyboard device according to a first embodiment of the present invention. The keyboard device  2  comprises plural key structures  20  and  20 ′. The plural key structures  20  and  20 ′ are exposed outside the keyboard device  2 . When one of the key structures  20  and  20 ′ is depressed by the user&#39;s finger, a corresponding key signal is generated to a computer (not shown) that is in communication with the keyboard device  2 . According to the key signal, the computer executes a function corresponding to the depressed key structure. The length of the key structure  20  is slightly larger than the width of the key structure  20 . The length L of the key structure  20 ′ is much larger than the width W of the key structure  20 ′. Consequently, the key structure  20 ′ is also referred as a multiple key. 
     The inner structure of the keyboard device  2  will be described as follows. For succinctness, only the key structure  20 ′ is shown.  FIG. 3  is a schematic exploded view illustrating a portion of the keyboard device according to the first embodiment of the present invention. In addition to the plural key structures  20  and  20 ′, the keyboard device  2  further comprises a base plate  21 , a switch circuit board  22 , an elastic cover  23  and a seal element  24 . The base plate  21  is located under the key structure  20 ′. The switch circuit board  22  is arranged between the key structure  20 ′ and the base plate  21 . When the switch circuit board  22  is triggered by the key structure  20 ′, the corresponding key signal is generated. A hollow region  220  of the switch circuit board  22  is exposed outside. The elastic cover  23  is disposed on the switch circuit board  22  and aligned with the hollow region  220 . Moreover, the hollow region  220  is covered by the elastic cover  23 . Consequently, the foreign liquid A (see  FIG. 4 ) is prevented from entering the switch circuit board  22 . The seal element  24  is disposed on sidewalls of the switch circuit board  22 . Consequently, a sealed region  25  (see  FIG. 4 ) is formed between the switch circuit board  22  and the elastic cover  23 . In such way, the foreign liquid A is prevented from entering the switch circuit board  22 . 
     Each of the key structures  20 ′ of the keyboard device  2  comprises a keycap  201 , at least one scissors-type connecting element  202 , an elastic element  203  and plural stabilizer bars  204 . The scissors-type connecting element  202  is connected with the corresponding keycap  201  and the base plate  21 . Through the scissors-type connecting element  202 , the keycap  201  is fixed on the base plate  21  and movable relative to the base plate  21 . The elastic element  203  is arranged between the corresponding keycap  201  and the switch circuit board  22 . When the elastic element  203  is pushed by the keycap  201 , the switch circuit board  22  is triggered. The plural stabilizer bars  204  are connected with the keycap  201  and the base plate  21 . As the plural stabilizer bars  204  are swung, the plural stabilizer bars  204  assist in the movement of the keycap  201 . Consequently, the moving stability of the keycap  201  is enhanced. In an embodiment, the base plate  21  and the plural stabilizer bars  204  are made of metallic material, the elastic element  203  is a rubbery elastomer, and the scissors-type connecting element  202  is made of plastic material. 
       FIG. 4  is a schematic side cross-sectional view illustrating a portion of the keyboard device according to the first embodiment of the present invention. Please refer to  FIGS. 3 and 4 . The switch circuit board  22  comprises an upper wiring plate  221 , a lower wiring plate  222 , a separation layer  223  and a key intersection  224 . The upper wiring plate  221  comprises a first opening  2211  and a first contact  2212 . The lower wiring plate  222  is located under the upper wiring plate  221 . Moreover, the lower wiring plate  222  comprises a second contact  2221  corresponding to the first contact  2212 . The separation layer  223  is arranged between the upper wiring plate  221  and the lower wiring plate  222 . Moreover, the separation layer  223  comprises a second opening  2231  and a third opening  2232 . The hollow region  220  is defined by the first opening  2211  and the second opening  2231  collaboratively. Moreover, the key intersection  224  is defined by the first contact  2212 , the second contact  2221  and the third opening  2232  collaboratively. In an embodiment, the switch circuit board  22  is a membrane circuit board, and the seal element  24  is a waterproof adhesive. 
     The sidewalls of the upper wiring plate  221 , the sidewalls of the separation layer  223  and the sidewalls of the lower wiring plate  222  are covered by the seal element  24 . Consequently, the seal element  24  is disposed on the sidewalls of the switch circuit board  22 . Generally, the spaces between the upper wiring plate  221 , the lower wiring plate  222  and the separation layer  223  of the switch circuit board  22  contain gas. After the seal element  24  is disposed on the sidewalls of the switch circuit board  22 , the gas is still contained in the sealed region  25  of the switch circuit board  22 . As shown in  FIG. 4 , the first opening  2211  of the upper wiring plate  221  is covered by the elastic cover  23  from the top side of the upper wiring plate  221 . Moreover, the elastic cover  23  is fixed on the upper wiring plate  221  by a hot pressing process or an attaching process. Consequently, the foreign liquid A is prevented from entering the sealed region  25  of the switch circuit board  22 . In an embodiment, the elastic cover  23  is made of silicone rubber. It is noted that the material of the elastic cover  23  is not restricted. 
     The operations of depressing the key structure  20 ′ will be described as follows. While the keycap  201  of any key structure  20 ′ is depressed, the keycap  201  is moved downwardly relative to the base plate  21 . Since the scissors-type connecting element  202  and the stabilizer bars  204  are pushed by the keycap  201 , the scissors-type connecting element  202  and the stabilizer bars  204  are correspondingly swung. Moreover, as the keycap  201  is moved downwardly to push the elastic element  203 , the elastic element  203  is subjected to deformation to trigger the key intersection  224  of the switch circuit board  22 . Moreover, as the first contact  2212  of the key intersection  224  is pushed by the elastic element  203 , the first contact  2212  is penetrated through the third opening  2232  and contacted with the second contact  2221 . Consequently, the electric connection between the first contact  2212  and the second contact  2221  is established, and the key intersection  224  is triggered to generate the corresponding key signal. When the key structure  20 ′ is no longer depressed by the user, the keycap  201  is moved upwardly relative to the base plate  21  in response to a restoring elastic force of the elastic element  203 . As the keycap  201  is moved upwardly, the scissors-type connecting element  202  and the stabilizer bars  204  are correspondingly swung and switched from a stacked state to an open-scissors state again. Consequently, the keycap  201  is returned to its original position. 
       FIG. 5  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the first embodiment of the present invention, in which the elastic cover is subjected to expansion. Please refer to  FIGS. 4 and 5 . When the temperature increases, the gas within the sealed region  25  of the switch circuit board  22  is thermally expanded and the volume of the inner gas increases. Due to the elastic cover  23  and the seal element  24 , the inner gas is not exhausted. Since the volume of the inner gas increases, the upper wiring plate  221 , the lower wiring plate  222  and the separation layer  223  are subjected to deformation. That is, the distance between the upper wiring plate  221  and the lower wiring plate  222  is increased. Moreover, the volume of the gas within the elastic cover  23  is also increased. Due to the elasticity of the elastic cover  23 , the increased volume of the inner gas is transferred to the elastic cover  23  and the elastic cover  23  is subjected to expansion. Consequently, as shown in  FIG. 5 , the space of the sealed region  25  is increased to accommodate the increased volume of the gas. In other words, the use of the elastic cover  23  can correct the deformation of the upper wiring plate  221 , the lower wiring plate  222  and the separation layer  223 . Since the distance between the first contact  2212  and the second contact  2221  is maintained, the electric connection between the first contact  2212  and the second contact  2221  can be established more easily. 
       FIG. 6  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the first embodiment of the present invention, in which the elastic cover is subjected to contraction. Please refer to  FIGS. 4 and 6 . When the temperature decreases, the gas within the sealed region  25  of the switch circuit board  22  is cooled and contracted and the volume of the inner gas decreases. Since the volume of the inner gas decreases, the upper wiring plate  221 , the lower wiring plate  222  and the separation layer  223  are subjected to deformation. That is, the distance between the upper wiring plate  221  and the lower wiring plate  222  is decreased. Moreover, the volume of the gas within the elastic cover  23  is also decreased. Due to the elasticity of the elastic cover  23 , the elastic cover  23  is subjected to contraction. Consequently, as shown in  FIG. 6 , the space of the sealed region  25  is decreased. In addition, the deformation of the switch circuit board  22  is compensated. In other words, the use of the elastic cover  23  can correct the deformation of the upper wiring plate  221 , the lower wiring plate  222  and the separation layer  223 . Since the distance between the first contact  2212  and the second contact  2221  is maintained, the first contact  2212  and the second contact  2221  are not erroneously touched. Consequently, the possibility of causing erroneous operation is reduced. 
     The present invention further provides a second embodiment, which is distinguished from the first embodiment.  FIG. 7  is a schematic cross-sectional side view illustrating a portion of a keyboard device according to a second embodiment of the present invention. The keyboard device  3  comprises plural key structures  30 ′, a base plate (not shown), a switch circuit board  32 , an elastic cover  33  and a seal element (not shown). Each of the key structures  30 ′ comprises a keycap (not shown), at least one scissors-type connecting element (not shown), an elastic element  303  and plural stabilizer bars (not shown). Except for the following two items, the structures and functions of the keyboard device  3  of this embodiment are substantially identical to those of the keyboard device of the first embodiment, and are not redundantly described herein. Firstly, the structure of the switch circuit board  32  is distinguished. Secondly, the arrangement of the elastic cover  33  is distinguished. 
     As shown in  FIG. 7 , the switch circuit board  32  comprises an upper wiring plate  321 , a lower wiring plate  322 , a separation layer  323  and a key intersection  324 . The upper wiring plate  321  comprises a first contact  3211 . The lower wiring plate  322  comprises a second contact  3222  corresponding to the first contact  3211 . Moreover, the lower wiring plate  322  further comprises a first opening  3222 . The separation layer  323  is arranged between the upper wiring plate  321  and the lower wiring plate  322 . Moreover, the separation layer  323  comprises a second opening  3231  and a third opening  3232 . A key intersection  324  is defined by the first contact  3211 , the second contact  3221  and the third opening  3232  collaboratively. Moreover, a hollow region  320  is defined by the first opening  3222  and the second opening  3231  collaboratively. In other words, the hollow region  320  is formed in a bottom surface of the switch circuit board  32 . As shown in  FIG. 7 , the first opening  3222  of the lower wiring plate  322  is covered by the elastic cover  33  from the bottom side of the lower wiring plate  322 . Moreover, the elastic cover  33  is fixed on the lower wiring plate  322  through a waterproof adhesive. The operations of the elastic cover  33  are similar to those of the first embodiment, and are not redundantly described herein. 
     The present invention further provides a third embodiment, which is distinguished from the above embodiments.  FIG. 8  is a schematic cross-sectional side view illustrating a portion of a keyboard device according to a third embodiment of the present invention. The keyboard device  4  comprises plural key structures  40 ′, a base plate (not shown), a switch circuit board  42 , an elastic cover  43  and a seal element (not shown). Each of the key structures  40 ′ comprises a keycap (not shown), at least one scissors-type connecting element (not shown), an elastic element  403  and plural stabilizer bars (not shown). 
     The switch circuit board  42  comprises an upper wiring plate  421 , a lower wiring plate  422 , a separation layer  423  and a key intersection  424 . The upper wiring plate  421  comprises a first opening  4211  and a first contact  4212 . The lower wiring plate  422  comprises a second contact  4221  corresponding to the first contact  4212 . The separation layer  423  is arranged between the upper wiring plate  421  and the lower wiring plate  422 . Moreover, the separation layer  423  comprises a second opening  4231  and a third opening  4232 . A hollow region  420  is defined by the first opening  4211  and the second opening  4231  collaboratively. Moreover, the key intersection  424  is defined by the first contact  4212 , the second contact  4221  and the third opening  4232  collaboratively. Except for the following item, the structures and functions of the keyboard device  4  of this embodiment are substantially identical to those of the keyboard device of the first embodiment, and are not redundantly described herein. For example, the structure of the elastic cover  43  is distinguished. 
       FIG. 9  is a schematic cross-sectional side view illustrating a portion of the keyboard device according to the third embodiment of the present invention, in which the elastic cover is subjected to expansion. Please refer to  FIGS. 8 and 9 . The elastic cover  43  comprises a tiny vent  431 . The tiny vent  431  runs through the elastic cover  43 . If the volume of the inner gas within the elastic cover  43  is not larger than a threshold value, the tiny vent  431  is sheltered in response to the elasticity of the elastic cover  43 . Meanwhile, the tiny vent  431  is in a closed state (see  FIG. 8 ). If the temperature increases abruptly, the gas within the sealed region  45  of the switch circuit board  42  is thermally expanded and the volume of the inner gas increases abruptly. Since the volume of the inner gas increases, the upper wiring plate  421 , the lower wiring plate  422  and the separation layer  423  are subjected to deformation. Moreover, the volume of the gas within the elastic cover  43  is also increased. Due to the elasticity of the elastic cover  43 , the increased volume of the inner gas is transferred to the elastic cover  43  and the elastic cover  43  is subjected to expansion. If the volume of the inner gas within the elastic cover  43  is larger than the threshold value, the elastic cover  43  is subjected to expansion again in response to the elasticity of the elastic cover  43  and the volume of the inner gas. Since the portion of the elastic cover  43  near the tiny vent  431  is propped open, the tiny vent  431  is in an opened state (see  FIG. 9 ). 
     When the tiny vent  431  is in the opened state, the inner gas is exhausted to the sealed region  45  through the tiny vent  431  is in an opened state. The inner gas is continuously exhausted until the volume of the inner gas within the elastic cover  43  is not larger than the threshold value. Consequently, the tiny vent  431  is in the closed state. Meanwhile, the function of the elastic cover  43  is similar to the function of the elastic cover  23  as shown in  FIG. 5 . In this embodiment, the elastic cover  43  has the function of an exhaust valve to compensate the deformation of the switch circuit board  42 . While the tiny vent  431  is opened, the pressure inside the switch circuit board  42  is higher than the pressure outside the switch circuit board  42 . Under this circumstance, the foreign liquid cannot be introduced into the switch circuit board  42  through the tiny vent  431 . Consequently, the elastic cover  43  with the tiny vent  431  still has the waterproof function. 
     In the above embodiments, the switch circuit board of the keyboard device is a three-layered structure. In some other embodiments, the elastic cover is applied to a two-layered switch circuit board. In the above embodiments, the elastic cover is disposed on the upper wiring plate or the lower wiring plate of the switch circuit board. It is noted that the position of the elastic cover is not restricted. For example, in another embodiment, the elastic cover is disposed on the separation layer, and the elastic cover is penetrated through the first opening of the upper wiring plate. In such way, the sealed region is also formed within the switch circuit board. In another embodiment, the elastic cover is inverted and disposed on the separation layer, and the elastic cover is penetrated through the first opening of the lower wiring plate. In such way, the sealed region is also formed within the switch circuit board. 
     From the above descriptions, the present invention provides the keyboard device. The elastic cover is disposed on the switch circuit board. Since no gas-escaping channel is installed in the switch circuit board, the sealed region in the switch circuit board can be maintained. Consequently, the keyboard device of the present invention has the waterproof function. When the temperature is changed and the inner gas within the switch circuit board is correspondingly changed, the elastic cover is subjected to expansion or contraction in response to the volume change of the inner gas and the elasticity of the elastic cover. Consequently, the distance between the first contact and the second contact of the switch circuit board can be maintained. In other words, the electric connection between the first contact and the second contact is established more easily and the problem of causing the erroneous operation is overcome. 
     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 modifications and similar structures.