Abstract:
The present invention discloses a keyboard including a plurality of keys and a membrane circuit board. Each key is used to trigger a corresponding membrane switch of the membrane circuit board. The membrane circuit board includes an antenna circuit. The antenna circuit is arranged inside the membrane circuit board, and not exposed to the upper surface or the lower surface of the membrane circuit board. The present invention increases an arranged area of the antenna circuit for improving the allowed length of the antenna circuit, so as to enhancing the transmission reception quality of wireless signals.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a keyboard, and more particularly to a keyboard with a function of transmitting or receiving a wireless signal. 
       BACKGROUND OF THE INVENTION 
       [0002]    As advancement of the technology development, the computer system and the peripherals thereof develop rapidly. In the modern computer system, the input device of the host plays an important role, wherein the input device comprises a keyboard, a mouse, a trackball, a presenter and so on. However, the keyboard is the most popular one of the input devices since users may process various paper works by pressing keys of a keyboard to input various words, numbers, or symbols. 
         [0003]    In general, the keyboard is connected with the host by wire, such as using a cable with a universal serial bus (USB) or a personal system/2 (PS/2) interface. However, the kind of connection manner may not only limit an operation distance of the keyboard from the computer due to the length of the cable of the keyboard, but also interfere the user with the cable during the user operating the keyboard. Thus, wireless keyboards substitute the wired keyboards and become more popular one due to resolving the issues. 
         [0004]      FIG. 1  illustrates a structural sectional view of a conventional wireless keyboard, and  FIG. 2  illustrates a partial structural view of the keyboard as illustrated in  FIG. 1 . Referring to  FIG. 1  and  FIG. 2 , the wireless keyboard  1  comprises a plurality of keys  10 , a membrane circuit board  13 , a circuit board  11  electrically connected with the membrane circuit board  13 , and a base  12  for carrying the above mentioned components, wherein the membrane circuit board  13  has a plurality of membrane switches  131 , and each of the keys  10  is disposed over each of the membrane switches  131  correspondingly. When any one of the keys  10  is pressed to move downwards, the key  10  pushes the corresponding one of the membrane switches  131  and thus switches on the corresponding one of the membrane switches  131 , so as to generate and transmit a corresponding key signal to the circuit board  11 . After that, an electronic component  111  on the circuit board  11  implements a signal processing to transform the key signal into a digital signal able to be read by the host (not shown). Moreover, the circuit board  11  has an antenna circuit  112 , and the wireless keyboard  1  transmits the wireless signal to the host by the antenna circuit  112 . Therefore, the key signal implemented with signal processing may be transmitted to the host by the antenna circuit  112 . 
         [0005]    In view of the modern electronic products tend to light, thin, short, and small more and more over, each of the components in the wireless keyboard  1  are also miniaturized to let the assembled wireless keyboard  1  is small and easy to be carried. Therefore, the circuit board  11  of the wireless keyboard  1  must have a small surface due to the forgoing limitation, and thus the arrangement area of the antenna circuit  112  on the circuit board  11  is reduced, and accordingly the transmission reception quality of the wireless signal of the wireless keyboard  1  is decreased. In another word, the length of the antenna circuit  112  is proportional to the transmission reception quality of the wireless signal of the wireless keyboard  1 . However, enlarging the size of the circuit board  11  for increasing the length of the disposed antenna circuit  112  may not only deviate from the design rule of light, thin, short, and small, but also increase the manufacturing cost of the circuit board  11 . Besides, an electromagnetic disturbance (EMI) effect is likely to be caused between the antenna circuit  112  disposed on the circuit board  11  and other electronic components  111  disposed on the circuit board  11 . Accordingly, the conventional wireless keyboard  1  needs to be improved. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a keyboard, wherein the arranged area of the antenna circuit is enlarged, so as to increase the length of the antenna circuit able to be arranged. 
         [0007]    In a preferred embodiment, the present invention provides a keyboard comprising:
       a membrane circuit board, comprising:
           a lower board, having a first circuit layout on an upper surface thereof, and the first circuit layout having a plurality of lower contacts;   an upper board, having a second circuit layout on an lower surface thereof, and the second circuit layout having a plurality of upper contacts corresponding to the plurality of lower contacts, wherein each of the plurality of upper contacts is distant from the corresponding one of the plurality of lower contacts with a distance and forms a membrane switch with the corresponding one of the plurality of lower contacts in common; and   an antenna membrane, having an antenna circuit, and the antenna circuit located between the antenna membrane and the lower board or between the antenna membrane and the upper board, wherein the keyboard transmits or receives a wireless signal by using the antenna circuit; and   
           a plurality of keys, for corresponding to and switching on the plurality of membrane switches.       
 
         [0013]    In a preferred embodiment, the antenna membrane is disposed under the lower board and the antenna circuit is formed on an upper surface of the antenna membrane, and thus the antenna circuit is located between the antenna membrane and the lower board. 
         [0014]    In a preferred embodiment, the antenna membrane is disposed over the upper board and the antenna circuit is formed on a lower surface of the antenna membrane, and thus the antenna circuit is located between the antenna membrane and the upper board. 
         [0015]    In a preferred embodiment, the antenna membrane is disposed between the upper board and the lower board, and the antenna circuit is located between the antenna membrane and the lower board when the antenna circuit is formed on a lower surface of the antenna membrane, or the antenna circuit is located between the antenna membrane and the upper board when the antenna circuit is formed on an upper surface of the antenna membrane. 
         [0016]    In a preferred embodiment, the membrane circuit board further comprises a middle board disposed between the lower board and the upper board, so as to form the distance between each of the upper contacts and the corresponding one of the lower contacts, and the middle board has a plurality of openings corresponding to the plurality of lower contacts and the plurality of upper contacts. 
         [0017]    In a preferred embodiment, the antenna membrane is disposed between the upper board and the middle board, and the antenna circuit is located between the antenna membrane and the middle board when the antenna circuit is formed on a lower surface of the antenna membrane, or the antenna circuit is located between the antenna membrane and the upper board when the antenna circuit is formed on an upper surface of the antenna membrane. 
         [0018]    In a preferred embodiment, the antenna membrane is disposed between the lower board and the middle board, and the antenna circuit is located between the antenna membrane and the lower board when the antenna circuit is formed on a lower surface of the antenna membrane, or the antenna circuit is located between the antenna membrane and the middle board when the antenna circuit is formed on an upper surface of the antenna membrane. 
         [0019]    In a preferred embodiment, each of the keys has a cap and an elastomer, and the elastomer is disposed between the cap and the membrane circuit board. The elastomer is compressed to push the corresponding one of the membrane switches when the cap is pressed. Alternatively, the elastomer provides an elastic force to the cap for returning the position of the cap when the cap is released. 
         [0020]    In a preferred embodiment, the present invention further provides a keyboard comprising:
       a membrane circuit board, comprising:
           a switch membrane, having a switch circuit layout on an upper surface thereof, and the switch circuit layout having a plurality of membrane switches; and   an antenna membrane, having an antenna circuit on an upper surface thereof, and the antenna membrane is disposed under the switch membrane, wherein the keyboard transmits or receives a wireless signal by using the antenna membrane; and   
           a plurality of keys, for corresponding to and switching on the plurality of membrane switches.       
 
         [0025]    In a preferred embodiment, each of the membrane switches comprises a first conductive portion and a second conductive portion, and the first conductive portion is separated from the second conductive portion. 
         [0026]    In a preferred embodiment, each of the keys has a cap and a conductor, the conductor is disposed between the cap and the membrane circuit board, and the conductor contacts and thus switches on the corresponding one of the membrane switches when the cap is pressed. 
         [0027]    In a preferred embodiment, the present invention also provides a keyboard comprising:
       a membrane circuit board, comprising:
           a lower board, having a first circuit layout on an upper surface thereof, and the first circuit layout having a plurality of lower contacts;   an upper board, having a second circuit layout on an lower surface thereof, and the second circuit layout having a plurality of upper contacts corresponding to the plurality of lower contacts, wherein each of the plurality of upper contacts is distant from the corresponding one of the plurality of lower contacts with a distance and forms a membrane switch with the corresponding one of the plurality of lower contacts in common; and   an antenna circuit, located between the lower board and the upper board, wherein the keyboard transmits or receives a wireless signal by using the antenna circuit; and   
           a plurality of keys, for corresponding to and switching on the plurality of membrane switches.       
 
         [0033]    In a preferred embodiment, the membrane circuit board further comprises a middle board disposed between the lower board and the upper board, so as to form the distance between each of the upper contacts and the corresponding one of the lower contacts, and the middle board has a plurality of openings corresponding to the plurality of lower contacts and the plurality of upper contacts. 
         [0034]    In a preferred embodiment, the antenna circuit is formed on an upper surface or a lower surface of the middle board. 
         [0035]    In a preferred embodiment, each of the keys has a cap and an elastomer, and the elastomer is disposed between the cap and the membrane circuit board. The elastomer is compressed to push the corresponding one of the membrane switches when the cap is pressed. Alternatively, the elastomer provides an elastic force to the cap for returning the position of the cap when the cap is released. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  illustrates a structural sectional view of a conventional wireless keyboard. 
           [0037]      FIG. 2  illustrates a partial structural view of the keyboard as illustrated in  FIG. 1 . 
           [0038]      FIG. 3  illustrates a structural sectional view of a keyboard according to a first preferred embodiment of the present invention. 
           [0039]      FIG. 4  illustrates a structural view of the membrane circuit board and the circuit board of the keyboard as illustrated in  FIG. 3 . 
           [0040]      FIG. 5  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 3 . 
           [0041]      FIG. 6  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a second preferred embodiment of the present invention. 
           [0042]      FIG. 7  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a third preferred embodiment of the present invention. 
           [0043]      FIG. 8  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a fourth preferred embodiment of the present invention. 
           [0044]      FIG. 9  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a fifth preferred embodiment of the present invention. 
           [0045]      FIG. 10  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a sixth preferred embodiment of the present invention. 
           [0046]      FIG. 11  illustrates a structural sectional view of the keyboard according to a seventh preferred embodiment of the present invention. 
           [0047]      FIG. 12  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 11 . 
           [0048]      FIG. 13  illustrates a structural sectional view of the keyboard according to an eighth preferred embodiment of the present invention. 
           [0049]      FIG. 14  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 13 . 
           [0050]      FIG. 15  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a ninth preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0051]    Reference will now be made in detail to specific embodiments of the present invention. Examples of these embodiments are illustrated in the accompanying drawings. While the invention will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to these embodiments. In fact, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. In the following description, numerous specific details are set forth in order to provide a through understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations are not described in detail in order not to obscure the present invention. 
         [0052]      FIG. 3  illustrates a structural sectional view of a keyboard according to a first preferred embodiment of the present invention,  FIG. 4  illustrates a structural view of the membrane circuit board and the circuit board of the keyboard as illustrated in  FIG. 3 , and  FIG. 5  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 3 . Referring to  FIG. 3  to  FIG. 5 , the keyboard  2  comprises a plurality of keys  20 , a membrane circuit board  23 , a circuit board  21  electrically connected with the membrane circuit board  23 , and a base  22  for carrying the above mentioned components. 
         [0053]    In the present embodiment, the membrane circuit board  23  comprises a lower board  231  and a upper board  232 . The lower board  231  has a first circuit layout  2311  on an upper surface thereof, and the first circuit layout  2311  has a plurality of lower contacts  23111 , while the upper board  232  has a second circuit layout  2321  on a lower surface thereof, and the second circuit layout  2321  has a plurality of upper contacts  23211  corresponding to the plurality of lower contacts  23111 . Herein, each of the upper contacts  23211  is distant from the corresponding one of the lower contacts  23111  with a distance D and forms a membrane switch  235  with the corresponding one of the lower contacts  23111  in common. In the present embodiment, the membrane circuit board  23  further comprises a middle board  233  disposed between the lower board  231  and the upper board  232 , so as to form the distance D between each of the upper contacts  23211  and the corresponding one of the lower contacts  23111 , wherein the middle board  233  has a plurality of openings  2331  corresponding to the plurality of lower contacts  23111  and the plurality of upper contacts  23211 . 
         [0054]    In addition, the plurality of keys  20  are disposed to where corresponding to the plurality of membrane switches  235 , and each key  20  of the plurality of keys  20  has a cap  201  and an elastomer  202 . The elastomer  202  is disposed between the cap  201  and the membrane circuit board  23 . When any one of the keys  20  is pressed to move downwards, the cap  201  of the key  20  compresses the elastomer  202  of the key  20  to let the elastomer  202  push the corresponding one of the upper contacts  23211 , and then let the corresponding one of the upper contacts  23211  contact the corresponding one of the lower contacts  23111  via the corresponding one of the openings  2331 . Hence, the corresponding one of the membrane switches  235  is switched on, so as to generate and transmit a corresponding key signal to the circuit board  21 . An electronic circuit  211  of the circuit board  21  further implements a signal processing to transform the key signal into a digital signal able to be read by a host (not shown). However, when the cap  201  is released, the position of the cap  201  returns upwards due to an elastic force of the elastomer  202 . 
         [0055]    The features of the present invention are illustrated herein after. The membrane circuit board  23  further comprises an antenna membrane  234  with an antenna circuit  2341 . A preferred approach of forming the antenna circuit  2341  on a surface of the antenna membrane  234  may be, but not limited to, an adhering process, a sputtering deposition process or a pressing process. Herein, the keyboard  2  may transmit wireless signals with the host (not shown) end via the antenna circuit  2341 . In another word, when any one of the membrane switches  235  is switched on to form a corresponding key signal, and the key signal is transformed into a digital signal able to be read by the host, the key signal is able to be transmitted to the host via the antenna circuit  2341 . In the present embodiment, the antenna membrane  234  is disposed under the lower board  231  and the antenna circuit  2341  is formed on an upper surface of the antenna membrane  234 , and thus the antenna circuit  2341  is located between the antenna membrane  234  and the lower board  231 . 
         [0056]      FIG. 6  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a second preferred embodiment of the present invention. Referring to  FIG. 6  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the first preferred embodiment of the present invention are omitted herein, for example, the middle board  243  of the membrane circuit board  24  is still located between the lower board  241  and the upper board  242 . What the present embodiment different to the above mentioned first preferred embodiment is that the antenna membrane  244  of the membrane circuit board  24  is disposed above the upper board  242 , and the antenna circuit  2441  is formed on a lower surface of the antenna membrane  244 , and thus the antenna circuit  2441  is located between the antenna membrane  244  and the upper board  242 . 
         [0057]      FIG. 7  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a third preferred embodiment of the present invention. Referring to  FIG. 7  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the first preferred embodiment of the present invention are omitted herein. What the present embodiment different to the above mentioned first preferred embodiment is that the antenna membrane  254  of the membrane circuit board  25  is disposed between the upper board  252  and the middle board  253 , and the antenna membrane  254  has a plurality of openings  2542  corresponding to the plurality of lower contacts  25111  and the plurality of upper contacts  25211 . Hence, each of the upper contacts  25211  may successfully contact the corresponding one of the lower contacts  25111  when being pushed by the elastomer (not shown). In the present embodiment, the antenna circuit  2541  is formed on the lower surface of the antenna membrane  254  and mismatched with the plurality of openings  2542  of the antenna membrane  254 , and thus the antenna circuit  2541  is located between the antenna membrane  254  and the lower board  251 . 
         [0058]      FIG. 8  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a fourth preferred embodiment of the present invention. Referring to  FIG. 8  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the third preferred embodiment of the present invention are omitted herein, for example, the antenna membrane  264  of the membrane circuit board  26  is still located between the upper board  262  and the middle board  263 , and the middle board  263  is still located between the antenna membrane  264  and the lower board  261 . What the present embodiment different to the above mentioned third preferred embodiment is that the antenna circuit  2641  of the membrane circuit board  26  is formed on the upper surface of the antenna membrane  264  and mismatched with the plurality of openings  2642  of the antenna membrane  264 , and thus the antenna circuit  2641  is located between the antenna membrane  264  and the upper board  262 . 
         [0059]      FIG. 9  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a fifth preferred embodiment of the present invention. Referring to  FIG. 9  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the first preferred embodiment of the present invention are omitted herein. What the present embodiment different to the above mentioned first preferred embodiment is that the middle board  273  of the membrane circuit board  27  is located between the upper board  272  and the antenna membrane  274 , and the antenna membrane  274  is disposed between the lower board  271  and the middle board  273  and has a plurality of openings  2742  corresponding to the plurality of lower contacts  27111  and the plurality of upper contacts  27211 . Hence, each of the upper contacts  27211  may successfully contact the corresponding one of the lower contacts  27111  when being pushed by the elastomer (not shown). In the present embodiment, the antenna circuit  2741  is formed on the lower surface of the antenna membrane  274  and mismatched with the plurality of openings  2742  of the antenna membrane  274 , and thus the antenna circuit  2741  is located between the antenna membrane  274  and the lower board  271 . 
         [0060]      FIG. 10  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a sixth preferred embodiment of the present invention. Referring to  FIG. 10  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the fifth preferred embodiment of the present invention are omitted herein, for example, the antenna membrane  284  of the membrane circuit board  28  is still located between the lower board  281  and the middle board  283 , and the middle board  283  is still located between the antenna membrane  284  and the upper board  282 . What the present embodiment different to the above mentioned fifth preferred embodiment is that the antenna circuit  2841  is formed on the upper surface of the antenna membrane  284  and mismatched with the plurality of openings  2842  of the antenna membrane  284 , and thus the antenna circuit  2841  is located between the antenna membrane  284  and the upper board  282 . 
         [0061]    It should be note that the antenna circuit of the antenna membrane in each of the first to sixth preferred embodiments is located between the antenna membrane and the lower board or between the antenna membrane and the upper board, but not exposed on the upper surface or the lower surface of the membrane circuit board, because a keyboard manufactured from the production line needs to be processed by an electrostatic discharge (ESD) test (which is well known by person having original skill in the art and omitted herein). In general, a circuit generated during the ESD test is conducted to a Ground line, and thus not to affect the operation of the keyboard. However, if the antenna circuit is formed on the upper surface or the lower surface of the membrane circuit board, the circuit generated during the ESD test is conducted to the circuit board via the antenna circuit, and thus electronic components mounted on the circuit board may be damaged. 
         [0062]    A seventh preferred embodiment of the present invention is illustrated hereinafter.  FIG. 11  illustrates a structural sectional view of the keyboard according to a seventh preferred embodiment of the present invention, and  FIG. 12  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 11 . Herein, the parts of the keyboard  3  in the present embodiment that is substantially similar to the keyboard as illustrated in the first preferred embodiment of the present invention are omitted herein. 
         [0063]    What the present embodiment different to the above mentioned first preferred embodiment is that the membrane circuit board  31  comprises a switch membrane  311  and an antenna membrane  314 . An upper surface of the switch membrane  311  has a circuit layout  3111 , and the circuit layout  311  has a plurality of membrane switches  31111 . Each of the membrane switches  31111  comprises a first conductive portion  311111  and a second conductive portion  311112 , and the first conductive portion  311111  is separated from the second conductive portion  311112 . In addition, the antenna membrane  314  is disposed under the switch membrane  311 , and the antenna circuit  3141  is formed on the upper surface of the antenna membrane  314 . Further, each of the keys  30  has a cap  301  and a conductor  302 , and the conductor  302  is disposed between the cap  301  and the membrane circuit board  31 . When any one of the caps  31  is pressed, the corresponding one of the conductors  302  contacts and thus switches on the corresponding one of the membrane switches  31111  to generate a corresponding key signal. Similarly, the key signal may be transformed into a digital signal able to be read by the host via a circuit board (not shown), and then transmitted to the host via the antenna circuit  3141 . 
         [0064]    An eighth preferred embodiment of the present invention is illustrated hereinafter. FIG.  13  illustrates a structural sectional view of the keyboard according to an eighth preferred embodiment of the present invention, and  FIG. 14  illustrates a perspective explosion view of the membrane circuit board of the keyboard as illustrated in  FIG. 13 . Herein, the parts of the keyboard  4  in the present embodiment that is substantially similar to the keyboard as illustrated in the first preferred embodiment of the present invention are omitted herein. 
         [0065]    What the present embodiment different to the above mentioned first preferred embodiment is that the membrane circuit board  41  doesn&#39;t comprise an antenna membrane  414 , and an antenna circuit  419  is directly formed on the lower surface of the middle board  413  and mismatched with the plurality of openings  4131  of the middle board  413 , and thus the antenna circuit  414  is located between the upper board  412  and the lower board  411  and not exposed on the upper surface or the lower surface of the membrane circuit board  41 . 
         [0066]      FIG. 15  illustrates a perspective explosion view of the membrane circuit board of the keyboard according to a ninth preferred embodiment of the present invention. Referring to  FIG. 15  hereinafter, the parts of the keyboard in the present embodiment that is substantially similar to the keyboard as illustrated in the eighth preferred embodiment of the present invention are omitted herein, for example, the antenna circuit  424  is located between the upper board  422  and the lower board  421 . What the present embodiment different to the above mentioned eighth preferred embodiment is that the antenna circuit  429  is directly formed on the upper surface of the middle board  423  and mismatched with the plurality of openings  4231  of the middle board  423 , and thus the antenna circuit  429  is not exposed on the upper surface or the lower surface of the membrane circuit board  42  as well. 
         [0067]    According to each of the above mentioned preferred embodiments, it is understood that the feature of the present invention is placing an antenna membrane in the membrane circuit board of the keyboard for disposing an antenna circuit. Therefore, comparing to the antenna circuit may only be disposed on a specific region of the circuit board in the conventional art, an advantage of the present invention is that the region for disposing the antenna circuit is larger. Accordingly, qualities of transmitting and receiving wireless signals by using the keyboard of the present invention are better, due to lengthening the length of the antenna circuit is possible. In addition, the antenna circuit is not disposed on the circuit board, and thus unable to generate EMI with other electronic components disposed on the circuit board. 
         [0068]    Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.