Abstract:
A keyboard. The keyboard comprises at least one key, a base, a membrane assembly and a circuit board. The membrane assembly is disposed between the base and the key. At least part of the circuit board is disposed in the key. The keyboard is connected to a notebook computer or a personal computer via a connection member.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a keyboard, and in particular to a keyboard detachably disposed on a notebook computer.  
         [0003]     2. Description of the Related Art  
         [0004]     A conventional notebook computer includes a keyboard inseparably disposed on a main body. A decoding circuit for decoding signals from keys of the keyboard is generally not disposed thereon, but in the main body of the notebook computer. Nor does the keyboard include a signal connection device for external electronic devices. Also, the keyboard does not include a conversion circuit for the signals from the keys into specific signals for the signal connection device to connect the external electronic devices. The keyboard thus has a single use.  
         [0005]     Another conventional notebook computer includes a detachable keyboard assembly with a keyboard circuit and signal connection device. The keyboard circuit decodes signals from the keys of the keyboard for conversion into specific signals for the signal connection device to connect external electronic devices. The keyboard circuit is disposed in an expansion module (such as a base or an expansion box). The expansion module is connected to a keyboard to enable the detachable keyboard assembly. In addition to use in the notebook computer, the detachable keyboard assembly can connect to other electronic devices through a connection member. The detachable keyboard assembly thus has multiple uses. Moreover, Taiwan patent No.  507900  discloses the aforementioned detachable keyboard assembly.  
         [0006]     The detachable keyboard assembly, however, is limited by the expansion module receiving the keyboard circuit. The expansion module increases the volume of the detachable keyboard assembly, causing difficulty in deployment of the detachable keyboard assembly in the notebook computer.  
         [0007]     Thus, there is a need to provide a detachable keyboard with reduced volume.  
       SUMMARY OF THE INVENTION  
       [0008]     Accordingly, the invention provides a keyboard comprising a first key, a second key, a membrane assembly and a circuit board. The membrane assembly is disposed under the first and second keys to output a first signal from the first key. At least part of the circuit board is disposed in the second key. The circuit board converts the first signal to a second signal.  
         [0009]     The second key is a dummy key or a space key.  
         [0010]     The keyboard further comprises a flexible printed circuit. The circuit board is a printed circuit board electrically connected to the membrane assembly via the flexible printed circuit.  
         [0011]     The circuit board is a flexible printed circuit electrically connected to the membrane assembly.  
         [0012]     The invention also provides a keyboard comprising a plurality of keys, a base, a membrane assembly and a circuit board. The base has a hole formed thereon. The membrane assembly is disposed between the base and the keys. At least part of the circuit board is disposed in the hole.  
         [0013]     The keyboard further comprises a flexible printed circuit. The circuit board is a printed circuit board electrically connected to the membrane assembly via the flexible printed circuit.  
         [0014]     The circuit board is a flexible printed circuit electrically connected to the membrane assembly.  
         [0015]     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0017]      FIG. 1  is an exploded perspective view of the keyboard of a first embodiment of the invention;  
         [0018]      FIG. 2  is an exploded perspective view of the keyboard of a second embodiment of the invention; and  
         [0019]      FIG. 3  is an exploded perspective view of the keyboard of a third embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0000]     First Embodiment  
         [0020]     Referring to  FIG. 1 , the keyboard  1  comprises a base  11 , a membrane assembly  12 , a printed circuit board (PCB)  14  and a plurality of keys  13 . The membrane assembly  12  is disposed on the base  11  and comprises an upper film (not shown), an intermediate film (not shown) and a lower film (not shown). The upper and lower films are respectively printed with circuits opposite each other. The intermediate film is not printed with any circuit and separates the upper film from the lower film. Specifically, the intermediate film separates the circuit on the upper film from that on the lower film. The keys  13  are disposed on the membrane assembly  12  and comprise multiple input keys and at least one dummy key  131 . The input keys can be pressed to generate corresponding signals. The interior of the dummy key  131  is hollow and the dummy key  131  cannot be pressed to output any signal. When one of the input keys is pressed, the upper and lower films corresponding to the position of this input key contact each other and are electrically conducted, outputting a signal to a keyboard circuit  141  deployed on the printed circuit board  14 . In this embodiment, the printed circuit board  14  (keyboard circuit  141 ) is disposed (inlaid) in the hollow inside of the dummy key  131  such that the keyboard circuit  141  does not increase the thickness of the keyboard  1 . A contact terminal  142  is welded on the printed circuit board  14 . The keyboard circuit  141  is electrically connected to the printed circuit board  14  via the contact terminal  142 . The printed circuit board  14  is connected to a flexible printed circuit  16  deployed with a first connection terminal  161  and a second connection terminal  162 . The first connection terminal  161  of the flexible printed circuit  16  is connected to a third connection terminal  121  of the membrane assembly  12  by thermal pressing, such that the flexible printed circuit  16  is electrically connected to the membrane assembly  12 . The second connection terminal  162  of the flexible printed circuit  16  is electrically connected to a contact terminal  151  of a signal connection device  15  by welding. The signal connection device  15  is in a corresponding position among the keys  13 . Namely, the signal connection device  15  and is keys  13  have the same height and are located on the same plane. The keyboard circuit  141  can include a keyboard signal decoding chip, a controlling chip for the signal connection device  15  and passive components. When one of the input keys is pressed to contact the membrane assembly  12 , the membrane assembly  12  generates a first signal corresponding to the input key. The first signal is transmitted to the keyboard circuit  141  and is thereby decoded and converted to a specific signal (second signal) for the signal connection device  15 . The specific signal (second signal) can be output to an external electronic device via the signal connection device  15 . The keyboard  1  is thus electrically connected to the external electronic device.  
         [0021]     Accordingly, since the printed circuit board  14  and keyboard circuit  141  thereon are inlaid in the hollow interior of the dummy key  131  and the flexible printed circuit  16  is extremely thin, the thickness of the keyboard  1  is not notably increased, maintaining volume.  
         [0000]     Second Embodiment  
         [0022]     Referring to  FIG. 2 , the keyboard  2  comprises a base  21 , a membrane assembly  22 , a flexible printed circuit (FPC)  24  and a plurality of keys  23 . The membrane assembly  22  is disposed on the base  21  and comprises an upper film (not shown), an intermediate film (not shown) and a lower film (not shown). The upper and lower films are respectively printed with circuits opposite each other. The intermediate film is not printed with any circuit and separates the upper film from the lower film. Specifically, the intermediate film separates the circuit on the upper film from that on the lower film. The keys  23  are disposed on the membrane assembly  22  and comprise multiple input keys. Specifically, a space key  231  of the input keys has a large hollow interior. The input keys can be pressed to generate corresponding signals. When one of the input keys is pressed, the upper and lower films corresponding to the position of this input key contact each other and are electrically conducted, outputting a signal to a keyboard circuit  241  deployed on the flexible printed circuit  24 . The keyboard circuit  241  includes chips, passive components and wires. In this embodiment, the keyboard circuit  241  is disposed (inlaid) in the hollow interior of the space key  231  such that the keyboard circuit  241  does not increase the thickness of the keyboard  2 . The chips and passive components of the keyboard circuit  241  are attached to the flexible printed circuit  24  by anisotropic conductive film (ACF) and thermal pressing. Additionally, the wires of the keyboard circuit  241  are laid on the flexible printed circuit  24 . The flexible printed circuit  24  has a first connection terminal  242  and a second connection terminal  243 . The first connection terminal  242  of the flexible printed circuit  24  is connected to a third connection terminal  221  of the membrane assembly  22  by thermal pressing, such that the flexible printed circuit  24  is electrically connected to the membrane assembly  22 . The second connection terminal  243  of the flexible printed circuit  24  is electrically connected to a contact terminal  251  of a signal connection device  25  by anisotropic conductive film (ACF) and thermal pressing. The signal connection device  25  is in a corresponding position among the keys  23 . Namely, the signal connection device  25  and keys  23  have the same height and are located on the same plane. Additionally, the chips of the keyboard circuit  241  can include a keyboard signal decoding chip and a controlling chip for the signal connection device  25 . When one of the input keys is pressed to contact the membrane assembly  22 , the membrane assembly  22  generates a first signal corresponding to the input key. The first signal is transmitted to the keyboard circuit  241  and is thereby decoded and converted to a specific signal (second signal) for the signal connection device  25 . The specific signal (second signal) can be output to an external electronic device via the signal connection device  25 . The keyboard  2  is thus electrically connected to the external electronic device.  
         [0023]     Accordingly, since the chips and passive components of the keyboard circuit  241  are inlaid in the hollow interior of the space key  231  and the flexible printed circuit  24  is extremely thin, the thickness of the keyboard  2  is not notably increased, maintaining volume.  
         [0000]     Third Embodiment  
         [0024]     Referring to  FIG. 3 , the keyboard  3  comprises a base  31 , a membrane assembly  32 , a flexible printed circuit (FPC)  34  and a plurality of keys  33 . The base  31  is formed with a through hole  311 . The membrane assembly  32  is disposed on the base  31  and comprises an upper film (not shown), an intermediate film (not shown) and a lower film (not shown). The upper and lower films are respectively printed with circuits opposite each other. The intermediate film is not printed with any circuit and separates the upper film from the lower film. Specifically, the intermediate film separates the circuit on the upper film from that on the lower film. The keys  33  are disposed on the membrane assembly  32  and comprise multiple input keys. The input keys can be pressed to generate corresponding signals. When one of the input keys is pressed, the upper and lower films corresponding to the position of this input key contact each other and are electrically conducted, outputting a signal to a keyboard circuit  341  deployed on the flexible printed circuit  34 . The keyboard circuit  341  includes chips, passive components and wires. In this embodiment, the keyboard circuit  341  is disposed in the through hole  311  of the base  31  such that the keyboard circuit  341  does not increase the thickness of the keyboard  3 . The chips and passive components of the keyboard circuit  341  are attached to the flexible printed circuit  34  disposed under the base  31  by anisotropic conductive film (ACF) and thermal pressing. Additionally, the wires of the keyboard circuit  341  are laid on the flexible printed circuit  34 . The flexible printed circuit  34  has a first connection terminal  342  and a second connection terminal  343 . The first connection terminal  342  of the flexible printed circuit  34  extends upwardly and across the outer edge of the base  31  to connect a third connection terminal  321  of the membrane assembly  32  by thermal pressing, such that the flexible printed circuit  34  is electrically connected to the membrane assembly  32 . The second connection terminal  343  of the flexible printed circuit  34  extends upwardly and across the outer edges of the base  31  and membrane assembly  32  to electrically connect a contact terminal  351  of a signal connection device  35  by anisotropic conductive film (ACF) and thermal pressing. The signal connection device  35  is in a corresponding position among the keys  33 . Namely, the signal connection device  35  and keys  33  have the same height and are located on the same plane. Additionally, the chips of the keyboard circuit  341  can include a keyboard signal decoding chip and a controlling chip for the signal connection device  35 . When one of the input keys is pressed to contact the membrane assembly  32 , the membrane assembly  32  generates a first signal corresponding to the input key. The first signal is transmitted to the keyboard circuit  341  and is thereby decoded and converted to a specific signal (second signal) for the signal connection device  35 . The specific signal (second signal) can be output to an s external electronic device via the signal connection device  35 . The keyboard  3  is thus electrically connected to the external electronic device.  
         [0025]     Accordingly, since the chips and passive components of the keyboard circuit  341  are disposed in the through hole  311  of the base  31  and the flexible printed circuit  34  is very thin, the thickness of the keyboard  3  is not notably increased, maintaining volume.  
         [0026]     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.