Patent Publication Number: US-9905381-B1

Title: Luminous keyboard

Description:
FIELD OF THE INVENTION 
     The present invention relates to a keyboard, and more particularly to a luminous keyboard with an illuminating function. 
     BACKGROUND OF THE INVENTION 
     Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard, a trackball device, or the like. Via the keyboard, characters and 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 keyboards. 
       FIG. 1  is a schematic top view illustrating the outer appearance of a conventional keyboard. As shown in  FIG. 1 , there are plural keys  10  on a surface of the conventional keyboard  1 . These keys  10  are classified into several types, e.g. ordinary keys  101 , numeric keys  102  and function keys  103 . When one of these keys  10  is depressed by the user&#39;s finger, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key. For example, when an ordinary key  101  is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key  102  is depressed, a corresponding number is inputted into the computer. In addition, the function keys  103  (F 1 ˜F 12 ) can be programmed to provide various functions. For example, the conventional keyboard  1  is a keyboard for a notebook computer. 
     With the maturity of the computing technologies, the keyboard manufacturers make efforts in designing novel keyboards with special functions in order to meet diversified requirements of different users. For this reason, luminous keyboards are favored by users. The outer appearance of the conventional luminous keyboard is substantially similar to the outer appearance of the conventional keyboard  1 . Since the luminous keyboard provides the function of illuminating the keys, the inner structure of the luminous keyboard is different from the inner structure of the keyboard without the illuminating function. Hereinafter, the inner structure of the luminous keyboard will be illustrated in more details.  FIG. 2  is a schematic cross-sectional view illustrating a conventional luminous keyboard. As shown in  FIG. 2 , the conventional luminous keyboard  2  comprises plural keys  20 , a membrane switch circuit board  21 , a light guide plate  22 , a backlight module  23 , a base plate  24  and a reflecting plate  25 . Each key  20  comprises a keycap  201 , a scissors-type connecting element  202  and an elastic element  203 . From top to bottom, the keycap  201 , the scissors-type connecting element  202 , the elastic element  203 , the membrane switch circuit board  21 , the base plate  24 , the light guide plate  22  and the reflecting plate  25  of the conventional luminous keyboard  2  are sequentially shown. The backlight module  23  is located at a side of the membrane switch circuit board  21 . For example, the conventional luminous keyboard  2  is a keyboard for a notebook computer (not shown). 
     In the key  20 , the keycap  201  is exposed outside the conventional luminous keyboard  2 , and thus the keycap  201  can be depressed by the user. The scissors-type connecting element  202  is used for connecting the keycap  201  and the base plate  24 . The elastic element  203  is penetrated through the scissors-type connecting element  202 . In addition, both ends of the elastic element  203  are contacted with the keycap  201  and the membrane switch circuit board  21 , respectively. The membrane switch circuit board  21  comprises an upper wiring plate  211 , a separation layer  212 , and a lower wiring plate  213 . The upper wiring plate  211 , the separation layer  212  and the lower wiring plate  213  are all made of a light-transmissible material. The light-transmissible material is for example polycarbonate (PC) or polyethylene (PE). The upper wiring plate  211  comprises an upper printed circuit pattern  2111  with plural upper contacts  2112 . The separation layer  212  is disposed under the upper wiring plate  211 , and comprises plural perforations  2121  corresponding to the plural upper contacts  2112 . The lower wiring plate  213  is disposed under the separation layer  212 . Moreover, the lower wiring plate  213  comprises a lower printed circuit pattern  2131  with plural lower contacts  2132  corresponding to the plural upper contacts  2112 . The plural lower contacts  2132  and the plural upper contacts  2112  are collectively defined as plural key switches  214 . 
     The backlight module  23  comprises an illumination circuit board  231  and plural light-emitting elements  232 . For clarification and brevity, only two light-emitting elements  232  are shown in the drawing. The illumination circuit board  231  is disposed under the membrane switch circuit board  21  and electrically connected with the light-emitting elements  232 . The illumination circuit board  231  provides electric power to the plural light-emitting elements  232 . The plural light-emitting elements  232  are disposed on the illumination circuit board  231 . In addition, the plural light-emitting elements  232  are inserted into plural reflecting plate openings  251  of the reflecting plate  25  and plural light guide plate openings  221  of the light guide plate  22 , respectively. By acquiring the electric power, the plural light-emitting elements  232  are driven to emit plural light beams B. Moreover, the plural light beams B are introduced into the light guide plate  22 . For example, the plural light-emitting elements  232  are side-view light emitting diodes. The plural light beams B are subjected to total internal reflection within the light guide plate  22 , and thus the plural light beams B are guided to the keycaps  201  by the light guide plate  22 . As shown in  FIG. 2 , the base plate  24  is arranged between the membrane switch circuit board  21  and the light guide plate  22 . The keycap  201 , the scissors-type connecting element  202 , the elastic element  203  and the membrane switch circuit board  21  are supported by the base plate  24 . The reflecting plate  25  is disposed under the light guide plate  22  for reflecting the plural light beams B. Consequently, the plural light beams B are directed upwardly, and the utilization efficiency of the light beams B is enhanced. 
     In the conventional luminous keyboard  2 , each keycap  201  has a light-outputting zone  2011 . The light-outputting zone  2011  is located at a character region or a symbol region of the keycap  201 . Moreover, the position of the light-outputting zone  2011  is aligned with the position of a corresponding light-guiding dot  223  of the light guide plate  22 . The light beams B can be guided upwardly to the light-outputting zone  2011  by the corresponding light-guiding dot  223 . The base plate  24  comprises plural base plate openings  241 . The plural base plate openings  241  are aligned with corresponding light-guiding dots  223  and corresponding light-outputting zones  2011 . On the other hand, since the membrane switch circuit board  21  is made of the light-transmissible material, the plural light beams B can be transmitted through the membrane switch circuit board  21 . Consequently, after the plural light beams B are guided by the light-guiding dots  223 , the plural light beams B are sequentially transmitted through the plural base plate openings  241  and the membrane switch circuit board  21  and directed to the plural light-outputting zones  2011 , thereby illuminating the character regions or the symbol regions of the keycaps  201 . Under this circumstance, the illuminating function is achieved. 
     However, the conventional luminous keyboard still has some drawbacks. For example, each of the upper printed circuit pattern  2111  and the lower printed circuit pattern  2131  of the membrane switch circuit board  21  is formed by printing plural silver conductor lines. As known, the resistance of silver is high. Moreover, the resistance tolerances of the upper printed circuit pattern  2111  and the lower printed circuit pattern  2131  are very large whenever the membrane switch circuit board  21  is produced. For example, the resistance tolerance is even up to several hundred ohms. For controlling the membrane switch circuit board  21  to generate the stable voltage, it is necessary to adjust the resistance value of the membrane switch circuit board  21  after the membrane switch circuit board  21  is produced. In other words, the use of the conventional membrane switch circuit board  21  increases the fabricating cost. 
     Therefore, there is a need of providing a luminous keyboard with reduced fabricating cost. 
     SUMMARY OF THE INVENTION 
     An object of the present invention provides a luminous keyboard with reduced fabricating cost. 
     In accordance with an aspect of the present invention, there is provided a luminous keyboard. The luminous keyboard includes plural keys, a membrane switch circuit board and a light-emitting element. The plural keys are exposed outside the luminous keyboard. The membrane switch circuit board is disposed under the plural keys. When the membrane switch circuit board is triggered by one of the plural keys, a corresponding key signal is generated. The membrane switch circuit board includes an upper wiring plate, a lower wiring plate, a conductor line pattern, a separation layer and an etched line pattern. The upper wiring plate is contacted with the plural keys. The lower wiring plate is disposed under the upper wiring plate and includes a wiring plate opening. The wiring plate opening runs through the lower wiring plate. The conductor line pattern is arranged between the upper wiring plate and the lower wiring plate. The separation layer is arranged between the upper wiring plate and the lower wiring plate. The upper wiring plate and the lower wiring plate are separated from each other by the separation layer. The etched line pattern is arranged between the separation layer and the lower wiring plate. The etched line pattern is exposed through the wiring plate opening. The light-emitting element is electrically connected with the etched line pattern through the wiring plate opening. The light-emitting element emits a light beam. 
     From the above descriptions, the present invention provides the luminous keyboard. The light-emitting element is installed on the membrane switch circuit board. Consequently, it is not necessary to install the illumination circuit board. Under this circumstance, the thickness of the luminous keyboard is reduced, and the luminous keyboard has the slim appearance. Moreover, the etched line pattern of the membrane switch circuit board can be used to replace a part or the entire of the printed conductor line layer. The etched line pattern is made of copper foil material. Since the resistance of copper is very stable, the problem of the conventional technology from the unstable resistance tolerances will be overcome. Moreover, the fabricating cost is reduced. 
     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 conventional keyboard; 
         FIG. 2  is a schematic cross-sectional view illustrating a conventional luminous keyboard; 
         FIG. 3  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a first embodiment of the present invention; 
         FIG. 4  is a schematic cross-sectional exploded view illustrating a portion of the luminous keyboard according to the first embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a second embodiment of the present invention; 
         FIG. 6  is a schematic cross-sectional exploded view illustrating a portion of the luminous keyboard according to the second embodiment of the present invention; 
         FIG. 7  is a schematic cross-sectional view illustrating the light-emitting element and the membrane switch circuit board of the luminous keyboard according to the second embodiment of the present invention; 
         FIG. 8  is a schematic top view illustrating the light-emitting element and the lower wiring plate of the luminous keyboard according to the second embodiment of the present invention; and 
         FIG. 9  is a schematic cross-sectional exploded view illustrating a portion of a luminous keyboard according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For overcoming the drawbacks of the conventional luminous keyboard, the present invention provides an improved luminous keyboard. 
     First of all, the structure of the luminous keyboard of the present invention will be illustrated as follows.  FIG. 3  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a first embodiment of the present invention. As shown in  FIG. 3 , the luminous keyboard  3 A comprises plural keys  30 A, a base plate  31 A, at least one light-emitting element  32 A, a membrane switch circuit board  33 A, a light guide plate  34 A and a reflecting plate  35 A. The plural keys  30 A are exposed outside a top surface of the luminous keyboard  3 A. The membrane switch circuit board  33 A is disposed under the plural keys  30 A. When the membrane switch circuit board  33 A is triggered by one of the plural keys  30 A, a corresponding key signal is generated. The base plate  31 A is arranged between the plural keys  30 A and the membrane switch circuit board  33 A, and connected with the plural keys  30 A. Each of the plural keys  30 A comprises a keycap  301 A, a connecting element  302 A and an elastic element  303 A. Each keycap  301 A has a light-outputting zone  304 A. The plural keycaps  301 A are exposed to the top surface of the luminous keyboard  3 A, so that the keycaps  301 A can be depressed by the user. The connecting elements  302 A are used for connecting the corresponding keycaps  301 A and the supporting plate  31 A and allowing the keycaps  301 A to be moved upwardly or downwardly relative to the supporting plate  31 A. The elastic elements  303 A are penetrated through the corresponding connecting elements  302 A, and contacted with the corresponding keycaps  301 A and the membrane switch circuit board  33 A. The elastic element  303 A provides an elastic force to the keycap  301 A. In response to the elastic force, the keycap  301 A is returned to its original position. 
     In this embodiment, the connecting element  302 A is a scissors-type connecting element, and the elastic element  303 A is a rubbery elastomer. Preferably but are not exclusively, the plural keycaps  301 A of the plural keys are moved upwardly or downwardly with the connecting elements  302 A, and the membrane switch circuit board  33 A is depressed by the elastic elements  303 A through the connecting elements  302 A. In another embodiment, the connecting elements are non-scissors connecting elements for controlling movements of the keys. For example, a crater-shaped connecting element for a desktop computer is one of the non-scissors connecting elements. In a further embodiment, the keycaps are moved upwardly or downwardly in response to magnetic forces. 
     Please refer to  FIG. 3  again. The light-emitting element  32 A is disposed on the membrane switch circuit board  33 A in an inverted form, and disposed under the plural keys  30 A. The light-emitting element  32 A is used for emitting a light beam B. The light guide plate  34 A is disposed under the plural keys  30 A, and located bedside the light-emitting element  32 A. The light beam B from the light-emitting element  32 A is laterally introduced into the light guide plate  34 A and guided by the light guide plate  34 A. Consequently, the light beam B is projected to the corresponding light-outputting zones  304 A. In this embodiment, the light guide plate  34 A comprises plural light-guiding structures  341 A and at least one light guide plate opening  342 A. Each light-guiding structure  341 A is aligned with the corresponding light-outputting zone  304 A. The light-guiding structures  341 A are used for guiding the light beam B to the corresponding light-outputting zones  304 A in order to illuminate the corresponding keys. The light guide plate opening  342 A is aligned with the light-emitting element  32 A. Moreover, the light-emitting element  32 A is inserted into the light guide plate opening  342 A. The reflecting plate  35 A is disposed under the light guide plate  34 A. Moreover, a portion of the light beam B exited from the light guide plate  34 A is reflected by the reflecting plate  35 A. Consequently, the leaked fraction of the light beam B is reduced, and the utilization efficiency of the light beam B is enhanced. In an embodiment, the light-emitting element  32 A is a side-view light emitting diode, and each light-guiding structure  341 A is one of a light-guiding microstructure, a light-guiding dot, a light-guiding ink and a light-guiding texturing structure. 
       FIG. 4  is a schematic cross-sectional exploded view illustrating a portion of the luminous keyboard according to the first embodiment of the present invention. Please refer to  FIGS. 3 and 4 . The membrane switch circuit board  33 A comprises an upper wiring plate  331 A, a lower wiring plate  332 A, a separation layer  333 A, a conductor line pattern  334 A and an etched line pattern  335 A. The upper wiring plate  331 A is contacted with the elastic elements  303 A. The conductor line pattern  334 A is printed on a bottom surface of the upper wiring plate  331 A. That is, the conductor line pattern  334 A is a printed conductor line layer. The lower wiring plate  332 A is disposed under the upper wiring plate  331 A. Moreover, the lower wiring plate  332 A comprises at least one wiring plate opening  3321 A. The wiring plate opening  3321 A runs through the lower wiring plate  332 A. The separation layer  333 A is arranged between the upper wiring plate  331 A and the lower wiring plate  332 A. When the key  30 A is not depressed, the upper wiring plate  331 A and the lower wiring plate  332 A are separated from each other by the separation layer  333 A. Moreover, the separation layer  333 A comprises plural perforations  3331 A corresponding to the plural keys  30 A. The etched line pattern  335 A is arranged between the separation layer  333 A and the lower wiring plate  332 A. Moreover, the wiring plate opening  3321 A is sheltered by the etched line pattern  335 A. Consequently, the etched line pattern  335 A is exposed through the wiring plate opening  3321 A of the lower wiring plate  332 A. Moreover, the conductor line pattern  334 A, the perforation  3331 A and the etched line pattern  335 A corresponding to one key  30 A are collaboratively defined as a key switch  336 A. In an embodiment, the conductor line pattern  334 A is made of silver. Moreover, the etched line pattern  335 A is formed by etching a copper foil layer. The way of forming the etched line pattern  335 A is well known to those skilled in the art, and is not redundantly described herein. 
     The light-emitting element  32 A is inserted into the wiring plate opening  3321 A and electrically connected with the etched line pattern  335 A. The light-emitting element  32 A comprises a conducting part  321 A and a light-outputting part  322 A. The conducting part  321 A is contacted with the etched line pattern  335 A. Through the conducting part  321 A, the light-emitting element  32 A is electrically connected with the etched line pattern  335 A to acquire electric power. The light beam B is outputted from the light-outputting part  322 A. When the light-emitting element  32 A is inserted into the wiring plate opening  3321 A, the conducting part  321 A is contacted with the etched line pattern  335 A and the light-outputting part  322 A is partially received in the wiring plate opening  3321 A. 
     As shown in  FIG. 4 , the luminous keyboard  3 A further comprises a first adhesive layer  36 A and a second adhesive layer  37 A. The first adhesive layer  36 A is arranged between the etched line pattern  335 A and the lower wiring plate  332 A. The etched line pattern  335 A is fixed on a top surface of the lower wiring plate  332 A through the first adhesive layer  36 A. The second adhesive layer  37 A is arranged between the separation layer  333 A and the etched line pattern  335 A. The etched line pattern  335 A and the lower wiring plate  332 A are fixed on a bottom surface of the separation layer  333 A through the second adhesive layer  37 A. In this embodiment, the first adhesive layer  36 A is a non-conductive adhesive layer. Moreover, the wiring plate opening  3321 A of the lower wiring plate  332 A is not sheltered by the first adhesive layer  36 A. That is, the first adhesive layer  36 A is not aligned with the wiring plate opening  3321 A. 
     The following three aspects should be specially described. Firstly, the base plate  31 A as shown in  FIG. 3  comprises plural first base plate openings  311 A and plural second base plate openings  312 A. Each of the first base plate openings  311 A is aligned with the corresponding key switch  336 A. While one of the plural keycaps  301 A is depressed by the user, a portion of the elastic element  303 A under the keycap  301 A is penetrated through the corresponding first base plate opening  311 A and contacted with the upper wiring plate  331 A. Each of the second base plate openings  312 A is aligned with the light-outputting zones  304 A of the corresponding keycap  301 A. After the light beam B is transmitted through the second base plate opening  312 A, the light beam B is projected to the light-outputting zones  304 A. 
     Secondly, the light-outputting part  322 A of the light-emitting element  32 A is partially received in the wiring plate opening  3321 A. Consequently, the light beam B from the light-outputting part  322 A is easily introduced into the light guide plate  34 A, and the light beam B is also easily projected to the lower wiring plate  332 A. Under this circumstance, a light leakage problem possibly occurs. For avoiding the light leakage problem, at least one of the lower wiring plate  332 A and the separation layer  333 A is made of an opaque material. Consequently, the light beam B cannot be introduced into the lower wiring plate  332 A or the separation layer  333 A. 
     Thirdly, in the above embodiment, the wiring plate opening  3321 A of the lower wiring plate  332 A is not sheltered by the first adhesive layer  36 A. Consequently, the conducting part  321 A of the light-emitting element  32 A can be contacted with the etched line pattern  335 A. It is noted that numerous modifications and alterations may be made while retaining the teachings of the invention. For example, in another embodiment, the first adhesive layer is a conductive adhesive layer. Since the first adhesive layer is electrically conductive, the wiring plate openings of the lower wiring plate can be sheltered by the first adhesive layer. When the light-emitting element is inserted in the wiring plate opening, the conducting part is contacted with the etched line pattern. 
     The operating principles of depressing the keycaps  301 A of the luminous keyboard  3 A to generate the key signals are well known to those skilled in the art, and are not redundantly described herein. 
     The present invention further provides a luminous keyboard of a second embodiment, which is distinguished from the above embodiment.  FIG. 5  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a second embodiment of the present invention.  FIG. 6  is a schematic cross-sectional exploded view illustrating a portion of the luminous keyboard according to the second embodiment of the present invention. As shown in  FIGS. 5 and 6 , the luminous keyboard  3 B comprises plural keys  30 B, a base plate  31 B, at least one light-emitting element  32 B, a membrane switch circuit board  33 B, a light guide plate  34 B, a reflecting plate  35 B, a first adhesive layer  36 B and a second adhesive layer  37 B. Each of the plural keys  30 B comprises a keycap  301 B, a connecting element  302 B and an elastic element  303 B. Each keycap  301 B has a light-outputting zone  304 B. The light guide plate  34 B comprises plural light-guiding structures  341 B and at least one light guide plate opening  342 B. Each light-guiding structure  341 B is aligned with the corresponding light-outputting zone  304 B. The membrane switch circuit board  33 B comprises an upper wiring plate  331 B, a lower wiring plate  332 B, a separation layer  333 B, a conductor line pattern  334 B and an etched line pattern  335 B. The lower wiring plate  332 B comprises plural wiring plate openings  3321 B. Moreover, the separation layer  333 B comprises plural perforations  3331 B corresponding to the plural keys  30 B. In comparison with the first embodiment, the arrangement of the light-emitting element  32 B of this embodiment is distinguished. The structures of the other components are similar to those of the first embodiment, and are not redundantly described herein. 
     Please refer to  FIGS. 5, 6, 7 and 8 .  FIG. 7  is a schematic cross-sectional view illustrating the light-emitting element and the membrane switch circuit board of the luminous keyboard according to the second embodiment of the present invention.  FIG. 8  is a schematic top view illustrating the light-emitting element and the lower wiring plate of the luminous keyboard according to the second embodiment of the present invention. As shown in  FIGS. 5 and 6 , the light-emitting element  32 B is disposed on the membrane switch circuit board  33 B in an inverted form, and disposed under the plural keys  30 B. The light-emitting element  32 B comprises plural conducting parts  321 B and a light-outputting part  322 B. Each conducting part  321 B is aligned with one corresponding wiring plate opening  3321 B. The conducting parts  321 B are contacted with the etched line pattern  335 B. Through the conducting parts  321 B, the light-emitting element  32 B is electrically connected with the etched line pattern  335 B to acquire electric power. The light beam B is outputted from the light-outputting part  322 B. The conducting parts  321 B of the light-emitting element  32 B are inserted in the corresponding wiring plate opening  3321 B and contacted with the etched line pattern  335 B. Moreover, as shown in  FIGS. 7 and 8 , the light-outputting part  322 B is not partially overlapped with the lower wiring plate  332 B. Since the light beam B from the light-outputting part  322 B is not introduced into the lower wiring plate  332 B and the separation layer  333 B, the light leakage problem is avoided. Under this circumstance, the lower wiring plate  332 B and the separation layer  333 Bare not made of the opaque material, and the light leakage problem is avoided. 
     The present invention further provides a luminous keyboard of a third embodiment, which is distinguished from the above embodiments.  FIG. 9  is a schematic cross-sectional exploded view illustrating a portion of a luminous keyboard according to a third embodiment of the present invention. Except for the following two items, the structures of the other components of the luminous keyboard  3 C of this embodiment are similar to those of the luminous keyboard  3 A of the first embodiment, and are not redundantly described herein. In comparison with the first embodiment, the membrane switch circuit board  33 C is distinguished. As shown in  FIG. 9 , the membrane switch circuit board  33 C comprises an upper wiring plate  331 C, a lower wiring plate  332 C, a separation layer  333 C, a conductor line pattern  334 C, a first etched line pattern  335 C and a second etched line pattern  336 C. The conductor line pattern  334 C is printed on a bottom surface of the upper wiring plate  331 C. The lower wiring plate  332 C is disposed under the upper wiring plate  331 C. Moreover, the lower wiring plate  332 C comprises at least one wiring plate opening  3321 C. The wiring plate opening  3321 C runs through the lower wiring plate  332 C. The separation layer  333 C is arranged between the upper wiring plate  331 C and the lower wiring plate  332 C. When the key  30 C is not depressed, the upper wiring plate  331 C and the lower wiring plate  332 C are separated from each other by the separation layer  333 C. Moreover, the separation layer  333 C comprises plural perforations  3331 C corresponding to the plural keys  30 C. 
     The first etched line pattern  335 C is arranged between the separation layer  333 C and the lower wiring plate  332 C. Moreover, the first etched line pattern  335 C is aligned with the wiring plate opening  3321 C, and the wiring plate opening  3321 C is sheltered by the first etched line pattern  335 C. Moreover, the conductor line pattern  334  and the first etched line pattern  335 C corresponding to one key  30 C are collaboratively defined as a key switch (not shown). The second etched line pattern  336 C is arranged between the lower wiring plate  332 C and the first etched line pattern  335 C. Moreover, the wiring plate opening  3321 C is not sheltered by the second etched line pattern  336 C. Moreover, the circuitry layout of the second etched line pattern  336 C is not aligned with the circuitry layout of the first etched line pattern  335 C. 
     As shown in  FIG. 9 , the luminous keyboard  3 C further comprises a first adhesive layer  36 C, a second adhesive layer  37 C and a third adhesive layer  38 C. The first adhesive layer  36 C is arranged between the second etched line pattern  336 C and the lower wiring plate  332 C. The second etched line pattern  336 C is fixed on a top surface of the lower wiring plate  332 C through the first adhesive layer  36 C. The second adhesive layer  37 C is arranged between the separation layer  333 C and the first etched line pattern  335 C. The first etched line pattern  335 C is fixed on a bottom surface of the separation layer  333 C through the second adhesive layer  37 C. The third adhesive layer  38 C is arranged between the first etched line pattern  335 C and the second etched line pattern  336 C. The first etched line pattern  335 C and the second etched line pattern  336 C are combined together through the third adhesive layer  38 C. As shown in  FIG. 9 , the membrane switch circuit board  33 C is further equipped with the second etched line pattern  336 C in order to increase the functionality of the membrane switch circuit board  33 C. For example, the second etched line pattern  336 C is electrically connected to an antenna (not shown) in order to transmit electric power to the antenna. 
     Moreover, the light-emitting element  32 C is penetrated through the wiring plate opening  3321 C, the first adhesive layer  36 C, the second etched line pattern  336 C and the third adhesive layer  38 C, and the conducting part  321 C of the light-emitting element  32 C is contacted with the etched line pattern  335 C. Through the conducting part  321 C, the light-emitting element  32 C is electrically connected with the first etched line pattern  335 C. Since the second etched line pattern  336 C and the third adhesive layer  38 C are not aligned with the wiring plate opening  3321 C, the electric connection between the second adhesive layer  37 C and the first etched line pattern  335 C is not hindered. In this embodiment, the second adhesive layer  37 C is a conductive adhesive layer. Consequently, the light-emitting element  32 C can acquire the electric power through the first etched line pattern  335 C. 
     Preferably but not exclusively, the conductor line pattern is a printed conductor line layer. In another embodiment, the conductor line pattern is also an etched line pattern. The conductor line pattern, the perforation and the etched line pattern are collaboratively defined as a key switch. Since the conductive wires of the key switch are all etched line patterns, the stability of the key switch is enhanced. Moreover, the conductive wires of the key switch can provide any other appropriate function (e.g., the function of connecting to the antenna). 
     From the above descriptions, the present invention provides the luminous keyboard. The light-emitting element is installed on the membrane switch circuit board. Consequently, it is not necessary to install the illumination circuit board. Under this circumstance, the thickness of the luminous keyboard is reduced, and the luminous keyboard has the slim appearance. Moreover, the etched line pattern of the membrane switch circuit board can be used to replace a part or the entire of the printed conductor line layer. The etched line pattern is made of copper foil material. Since the resistance of copper is very stable, it is necessary to adjust the resistance value of the membrane switch circuit board during the process of fabricating the luminous keyboard. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all modifications and similar structures.