Patent Publication Number: US-8536476-B2

Title: Illuminated keyboard

Description:
FIELD OF THE INVENTION 
     The present invention relates to a keyboard, and more particularly to an illuminated keyboard with an illuminating function. 
     BACKGROUND OF THE INVENTION 
     A keyboard is one of the widely-used computer peripheral devices. Via the keyboard, the user may input characters and instructions into a computer.  FIG. 1  is a schematic top view illustrating the outward appearance of a conventional keyboard. The surface of the conventional keyboard  1  includes plural keys. These keys  10  are classified into several types, e.g. ordinary keys  101 , numeric keys  102  and function keys  103 . When one or more keys are depressed by a user, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key or keys. 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  102  (F1˜F12) can be programmed to cause corresponding application programs to provide certain functions. 
     With the maturity of the computing technologies, the conventional keyboard that has basic functions fails to meet the requirements of various users. For this reason, the keyboard manufacturers make efforts in designing novel keyboards with diversified functions. Recently, an illuminated keyboard with an illuminating function has been disclosed. Since the outward appearance of the conventional illuminated keyboard is similar to the outward appearance of the conventional keyboard  1 , only the inner structure of the conventional illuminated keyboard will be illustrated in more details as follows. 
       FIG. 2  is a schematic cross-sectional view illustrating a conventional illuminated keyboard. As shown in  FIG. 2 , the illuminated keyboard  2  comprises plural keys  20 , a membrane switch circuit member  21 , a light guide plate  22 , an illumination module  23 , a main circuit board  24 , a reflector  25  and a base plate  26 . The key  20  comprises a keycap  201 , a key housing  202  and an elastic element  203 . From top to bottom, the keycap  201 , the key housing  202 , the elastic element  203 , the membrane switch circuit member  21 , the light guide plate  22 , the reflector  25  and the base plate  26  of the conventional illuminated keyboard  2  are sequentially shown. The main circuit board  24  is arranged at a second side of the membrane switch circuit member  21 . The illumination module  23  is arranged at a first side of the membrane switch circuit member  21 . 
     In the key  20 , the keycap  201  is exposed outside the surface of the illuminated keyboard  2 , so that the keycap  201  can be depressed by the user. The key housing  202  is used for fixing the keycap  201  and the elastic element  203 . The elastic element  203  is penetrated through the key housing  202 . In addition, both ends of the elastic element  203  are contacted with the keycap  201  and the membrane switch circuit member  21 , respectively. The membrane switch circuit member  21  comprises an upper wiring board  211 , a partition plate  212  and a lower wiring board  213 . The upper wiring board  211 , the partition plate  212  and the lower wiring board  213  are made of a transparent material. The transparent material includes for example polycarbonate (PC) or polyethylene (PE). The upper wiring board  211  has plural upper contacts  2111 . The partition plate  212  is disposed under the upper wiring board  211 , and comprises plural partition plate openings  2121  corresponding to the plural upper contacts  2111 . The lower wiring board  213  is disposed under the partition plate  212 , and comprises plural lower contacts  2131  corresponding to the plural upper contacts  2111 . The plural lower contacts  2131  and the plural upper contacts  2111  are collectively defined as plural key intersections. Moreover, the membrane switch circuit member  21  is connected with the main circuit board  24  for transmitting first electric power and signals. 
     The illumination module  23  comprises an illumination circuit board  231  and plural light emitting diodes  232 . For clarification and brevity, only a light emitting diode  232  is shown in the drawing. The illumination circuit board  231  is arranged at the first side of the membrane switch circuit member  21  for providing second electric power to the plural light emitting diodes  232 . The light guide plate  22  has plural light-guiding zones  221 . Each of the light-guiding zones  221  has plural light-guiding dots  2211 . The light-guiding dots  2211  of each light-guiding zone  221  are uniformly distributed. In addition, each light-guiding zone  221  has plural gaps G. For clarification and brevity, only a gap G is shown in the drawing. The light-guiding dots  2211  are used for guiding the plural light beams to the keycaps  201 . A process of forming the light-guiding dots  2211  will be illustrated as follows. 
     Firstly, a stencil with plural mesh openings is placed on a bottom surface  222  of the light guide plate  22 . Then, light-guiding ink is poured to the stencil such that the light-guiding ink flows to the bottom surface  222  of the light guide plate  22  through the mesh openings. Then, the light-guiding ink is subject to a screen printing process, so that the light-guiding ink is printed on the bottom surface  222  of the light guide plate  22  to result in plural light-guiding dots  2211 . As shown in  FIG. 3 , each of the light-guiding zones  221  that is formed by using the stencil with plural mesh openings comprises plural light-guiding dots  2211 , wherein every two light-guiding dots  2211  are spaced from each other by the gap G. 
     As shown in  FIG. 2 , the reflector  25  of the illuminated keyboard  2  is disposed under the light guide plate  22  for reflecting the light beams. The base plate  26  is disposed under the reflector  25  for supporting the keycap  201 , the key housing  202 , the elastic element  203 , the membrane switch circuit member  21 , the light guide plate  22  and the reflector  25 . 
     In the conventional illuminated keyboard  2 , the keycap  201  has a light-transmissible region  2011 . The light-transmissible region  2011  is located at a character region or a symbol region of the keycap  201 . Moreover, the position of the light-transmissible region  2011  is aligned with a corresponding light-guiding zone  221  of the light guide plate  22 . In such way, the light beams can be guided to the light-transmissible region  2011  through the light-guiding dots  2211  of the light-guiding zone  221 , thereby illuminating the character region or the symbol region of the keycap  201 . Consequently, the illuminating efficacy is achieved. 
     However, after the conventional illuminated keyboard  2  is used for a long time, some drawbacks occur. For example, since the plural keys  20  are frequently depressed, the light-guiding dots  2211  of the light guide plate  22  will be suffered from abrasion. Since there is a vacant space G between adjacent light-guiding dots  2211 , the possibility of abrading the peripheries of the light-guiding dots  2211  will be increased. In addition, the abrasion at the periphery of the light-guiding zone  221  becomes more serious. Under this circumstance, these light-guiding dots  2211  fail to be uniformly distributed, and thus the light-guiding efficacy thereof is deteriorated. 
     SUMMARY OF THE INVENTION 
     The present invention provides an illuminated keyboard for reducing the possibility of deteriorating the light-guiding efficacy. 
     In accordance with an aspect of the present invention, there is provided an illuminated keyboard. The illuminated keyboard includes plural keys, a membrane switch circuit member, an illumination module and a light guide plate. The membrane switch circuit member has plural key intersections corresponding to the plural keys. The illumination module is arranged at a first side of the membrane switch circuit member for emitting plural light beams. The light guide plate is stacked on the membrane switch circuit member and disposed under the membrane switch circuit member. The light guide plate has plural light-guiding zones corresponding to the plural key intersections. The plural light-guiding zones are formed on a bottom surface of the light guide plate and arranged beside respective key intersections for guiding the plural light beams to the plural keys. Each of the light-guiding zones includes a light-guiding layer. The light-guiding zone is filled with the corresponding light-guiding layer, so that no vacant space is formed in the light-guiding zone. 
     In an embodiment, each of the light-guiding layers is made of light-guiding ink, and each of the light-guiding zones is filled with the light-guiding ink. 
     In an embodiment, the illuminated keyboard further includes a main circuit board and a base plate. The main circuit board is connected with the membrane switch circuit member for providing first electric power to the membrane switch circuit member . The base plate is disposed under the light guide plate for supporting the plural keys, the membrane switch circuit member, the illumination module, the light guide plate and the main circuit board. 
     In an embodiment, the illumination module includes an illumination circuit board and plural light emitting diodes. The illumination circuit board is arranged at the first side of the membrane switch circuit member for providing second electric power. The plural light emitting diodes are mounted on the illumination circuit board for acquiring the second electric power, thereby emitting the plural light beams. 
     In an embodiment, the membrane switch circuit member includes an upper wiring board, a partition plate and a lower wiring board. The upper wiring board has plural upper contacts. The partition plate is disposed under the upper wiring board, and has plural partition plate openings corresponding to the plural upper contacts. When the membrane switch circuit member is depressed, a corresponding upper contact is inserted into a corresponding partition plate opening. The lower wiring board is disposed under the partition plate, and has plural lower contacts corresponding to the plural upper contacts, wherein the plural lower contacts and the plural upper contacts are collectively defined as the plural key intersections. 
     In accordance with another aspect of the present invention, there is provided an illuminated keyboard. The illuminated keyboard includes plural keys, a membrane switch circuit member and an illumination module. The membrane switch circuit member has plural key intersections corresponding to the plural keys and plural light-guiding zones corresponding to the plural key intersections. The plural light-guiding zones are formed on a bottom surface of the light guide plate. Each of the light-guiding zones includes a light-guiding layer. The light-guiding zone is filled with the corresponding light-guiding layer, so that no vacant space is formed in the light-guiding zone. The illumination module is arranged at a first side of the membrane switch circuit member for emitting plural light beams. The plural light beams are projected on the plural light-guiding zones and guided to the plural keys by the plural light-guiding zones. 
     In an embodiment, each of the light-guiding layers is made of light-guiding ink, and each of the light-guiding zones is filled with the light-guiding ink. 
     In an embodiment, the membrane switch circuit member includes an upper wiring board, a partition plate and a lower wiring board. The upper wiring board has plural upper contacts. The partition plate is disposed under the upper wiring board, and has plural partition plate openings corresponding to the plural upper contacts. When the membrane switch circuit member is depressed, a corresponding upper contact is inserted into a corresponding partition plate opening. The lower wiring board is disposed under the partition plate, and has plural lower contacts corresponding to the plural upper contacts and the plural light-guiding zones. The plural lower contacts and the plural upper contacts are collectively defined as the plural key intersections. The plural light-guiding zones are formed on a bottom surface of the lower wiring board. In an embodiment, the illuminated keyboard further includes a main circuit board and a base plate. The main circuit board is connected with the membrane switch circuit member and the illumination module for providing first electric power to the membrane switch circuit member and the illumination module. The base plate is disposed under the membrane switch circuit member for supporting the plural keys and the membrane switch circuit member. 
     In an embodiment, each of the keys includes a keycap, a scissors-type connecting element and an elastic element. The keycap is exposed to a surface of the illuminated keyboard, and includes a light-transmissible region corresponding to one of the plural light-guiding zones. The scissors-type connecting element is arranged between the base plate and the keycap for connecting the base plate and the keycap, and allowing the keycap to be moved upwardly and downwardly with respect to the base plate. The elastic element is arranged between the membrane switch circuit member and the keycap. When the keycap is pressed, the elastic element is compressed to push against the membrane switch circuit member, so that a corresponding upper contact is contacted with a corresponding lower contact. Whereas, when a depressing force exerted on the keycap is eliminated, an elastic force provided by the elastic element is acted on the keycap, so that the keycap is returned to an original position. 
     In an embodiment, the illumination module includes an illumination circuit board and plural light emitting diodes. The illumination circuit board is arranged at the first side of the membrane switch circuit member for providing second electric power. The plural light emitting diodes are mounted on the illumination circuit board for acquiring the second electric power, thereby emitting the plural light beams. 
     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 outward appearance of a conventional keyboard; 
         FIG. 2  is a schematic cross-sectional view illustrating a conventional illuminated keyboard; 
         FIG. 3  is a schematic top view illustrating a light guide plate of a conventional illuminated keyboard; 
         FIG. 4  is a schematic cross-sectional view illustrating an illuminated keyboard according to a first embodiment of the present invention; 
         FIG. 5  is a schematic exploded view illustrating the membrane switch circuit member, the light guide plate and the illumination module of the illuminated keyboard according to the first embodiment of the present invention; 
         FIG. 6  is a schematic cross-sectional view illustrating an illuminated keyboard according to a second embodiment of the present invention; and 
         FIG. 7  is a schematic exploded view illustrating the membrane switch circuit member and the illumination module of the illuminated keyboard according to the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For obviating the drawbacks encountered from the prior art, the present invention provides illuminated keyboard.  FIG. 4  is a schematic cross-sectional view illustrating an illuminated keyboard according to a first embodiment of the present invention. As shown in  FIG. 4 , the illuminated keyboard comprises plural keys  30 , a membrane switch circuit member  31 , a light guide plate  32 , an illumination module  33 , a main circuit board  34 , a reflector  35  and a base plate  36 . The key  30  comprises a keycap  301 , a key housing  302  and an elastic element  303 . From top to bottom, the keycap  301 , the key housing  302 , the elastic element  303 , the membrane switch circuit member  31 , the light guide plate  32 , the reflector  35  and the base plate  36  of the conventional illuminated keyboard  3  are sequentially shown. The main circuit board  34  is arranged at a second side of the membrane switch circuit member  31 . The illumination module  33  is arranged at a first side of the membrane switch circuit member  31 . In this embodiment, the illuminated keyboard  3  is a keyboard for a desktop computer. The first side of the membrane switch circuit member  31  denotes the front side of the membrane switch circuit member  31 , i.e. the side of the illuminated keyboard  3  having the space bar. The second side of the membrane switch circuit member  31  denotes the rear side of the membrane switch circuit member  31 , i.e. the side of the illuminated keyboard  3  having the function key F 1 . 
     In the key  30 , the keycap  301  is exposed outside the surface of the illuminated keyboard  3 , so that the keycap  301  can be depressed by the user. In addition, the keycap  301  has a light-transmissible region  3011 . The light-transmissible region  3011  is located at a character region or a symbol region of the keycap  301 . The key housing  302  is used for fixing the keycap  301  and the elastic element  303 . The elastic element  303  is penetrated through the key housing  302 . In addition, both ends of the elastic element  303  are contacted with the keycap  301  and the membrane switch circuit member  31 , respectively. In this embodiment, the elastic element  303  is made of a transparent rubbery material. Moreover, the membrane switch circuit member  31  is connected with the main circuit board  34  for transmitting first electric power and signals. 
       FIG. 5  is a schematic exploded view illustrating the membrane switch circuit member, the light guide plate and the illumination module of the illuminated keyboard according to the first embodiment of the present invention. The membrane switch circuit member  31  comprises an upper wiring board  311 , a partition plate  312  and a lower wiring board  313 . The upper wiring board  311  has plural upper contacts  3111 . The partition plate  312  is disposed under the upper wiring board  311 , and comprises plural partition plate openings  3121  corresponding to the plural upper contacts  3111 . The lower wiring board  313  is disposed under the partition plate  312 , and comprises plural lower contacts  3131  corresponding to the plural upper contacts  3111 . The plural lower contacts  3131  and the plural upper contacts  3111  are collectively defined as plural key intersections. In this embodiment, the upper wiring board  311 , the partition plate  312  and the lower wiring board  313  are made of a transparent material such as polycarbonate (PC) or polyethylene (PE). 
     Please refer to  FIGS. 4 and 5  again. The illumination module  33  comprises an illumination circuit board  331  and plural light emitting diodes  332 . The illumination circuit board  331  is arranged at the first side of the membrane switch circuit member  31  for providing second electric power to the plural light emitting diodes  332 . The plural light emitting diodes  332  are mounted on the illumination circuit board  331 . By acquiring the second electric power, the plural light emitting diodes  332  are enabled to emit plural light beams. In this embodiment, the plural light emitting diodes  332  are side-view light emitting diodes. Each of the light-guiding zones  321  comprises a light-guiding layer  3211 . The light-guiding zone  321  is filled with the corresponding light-guiding layer  3211 , so that no vacant space is formed in the light-guiding zone  321 . By the light-guiding layer  3211 , the plural light beams are guided to the keycaps  301  and transmitted through the light-transmissible regions  3011 . In this embodiment, the light-guiding zones  321  and the light-guiding layers  3211  are all rectangular. The process of forming each of the light-guiding layers  3211  is similar to the process of forming the conventional light-guiding dots. Firstly, a stencil with plural rectangular openings is placed on a bottom surface  322  of the light guide plate  32 . Then, light-guiding ink is poured to the stencil such that the light-guiding ink flows to the bottom surface  322  of the light guide plate  32  through the plural rectangular openings. Then, the light-guiding ink is subject to a screen printing process, so that the light-guiding ink is printed on the bottom surface  322  of the light guide plate  32  to result in plural rectangular light-guiding layers  3211 . Since the light-guiding layer  3211  is formed by completely filling the rectangular opening with the light-guiding ink, the light-guiding zone  321  is filled with the corresponding light-guiding layer  3211 . Under this circumstance, no vacant space is formed in the light-guiding zones  321 . 
     As shown in  FIG. 4 , the reflector  35  is disposed under the light guide plate  32  for reflecting the light beams. The base plate  36  is disposed under the reflector  35  for supporting the keycap  301 , the key housing  302 , the elastic element  303 , the membrane switch circuit member  31 , the light guide plate  32  and the reflector  35 . After the above components are combined together, the illuminated keyboard  3  is assembled. When the keycap  301  is depressed by a user, the keycap  301  is moved downwardly with respect to the key housing  302 . At the same time, the elastic element  303  is compressed to push against the membrane switch circuit member  31 , so that the upper contact  3111  is inserted into a corresponding partition plate opening  3121  to be contacted with a corresponding lower contact  3131 . Under this circumstance, a corresponding key intersection of the membrane switch circuit member  31  is triggered to generate a key signal. Whereas, when the depressing force exerted on the key  301  is eliminated, an elastic force provided by the elastic element  303  is acted on the keycap  301 . Due to the elastic force, the keycap  301  is returned to its original position. After the plural light beams emitted by the plural light emitting diodes  322  of the illumination module  32  are directed to the light guide plate  32 , some of the light beams are guided to the light-transmissible regions  3011  of the keycaps  301  by the light-guiding layers  3211  of the light guide plate  32 . At the same time, some of the light beams are reflected by the reflector  35  under the light guide plate  32 , and the reflected light beams are directed to the light-guiding layers  3211  again to be guided by the light-guiding layers  3211 . 
     From the above description, the light-guiding layer  3211  is an integral rectangular layer. In other words, the peripheries of the light-guiding layer  3211  are the four sides of the rectangle. In comparison with the light-guiding dots  2211  of the light-guiding zone  221 , since the rectangular light-guiding layer  3211  has no vacant space, the peripheries of the light-guiding layer  3211  are the four sides of the rectangle. Moreover, since the peripheries of the light-guiding layer  3211  are smaller than the peripheries of the plural light-guiding dots  2211 , the possibility of abrading the light-guiding layer  3211  through a long-term collision will be reduced. Moreover, since the light-guiding layer  3211  is rectangular and the stencil for performing the screen printing process have the same size of rectangular openings as the light-guiding zones  321 , the rectangular openings can be easily filled with the light-guiding ink during the printing process. Moreover, after the printing process is finished, the light-guiding ink is seldom retained in the stencil with the rectangular openings. On contrast, since the conventional stencil for forming the light-guiding dots has small mesh openings, the light-guiding ink is easily retained in the stencil. Moreover, in a case that the conventional stencil with the small mesh openings is repeatedly used, a portion of the light-guiding ink to be printed on the light-guiding zone may be adsorbed or bonded by the residual light-guiding ink of the stencil. Under this circumstance, the light-guiding ink printed on the light-guiding zone is insufficient, and thus the light-guiding efficacy thereof is deteriorated. On the other hand, since stencil of the present invention for printing the light-guiding ink has larger-sized rectangular openings, the light-guiding ink is rarely retained in the stencil during the process of forming the light-guiding layer. Since the light-guiding ink is filled with the light-guiding zone, the light-guiding efficacy is enhanced. In addition, the production yield during the printing process is increased, and the fabricating cost is reduced. 
     The present invention further provides an illuminated keyboard of a second embodiment.  FIG. 6  is a schematic cross-sectional view illustrating an illuminated keyboard according to a second embodiment of the present invention. As shown in  FIG. 6 , the illuminated keyboard  4  comprises plural keys  40 , a membrane switch circuit member  41 , an illumination module  42 , a main circuit board  43 , a reflector  44  and a base plate  45 . The key  40  comprises a keycap  401 , a scissors-type connecting element  402  and an elastic element  403 . From top to bottom, the keycap  401 , the scissors-type connecting element  402 , the elastic element  403 , the membrane switch circuit member  41 , the reflector  44  and the base plate  45  of the illuminated keyboard  4  are sequentially shown. The illumination module  42  is arranged at a first side of the membrane switch circuit member  41 . The main circuit board  43  is arranged at a second side of the membrane switch circuit member  41 . In this embodiment, the illuminated keyboard  4  is a keyboard for a notebook computer. The first side of the membrane switch circuit member  41  denotes the front side of the membrane switch circuit member  41 , i.e. the side of the illuminated keyboard  4  having the space bar. The second side of the membrane switch circuit member  41  denotes the rear side of the membrane switch circuit member  41 , i.e. the side of the illuminated keyboard  4  having the function key F1. 
     In the key  40 , the keycap  401  is exposed outside the surface of the illuminated keyboard  4 , so that the keycap  401  can be depressed by the user. In addition, the keycap  401  has a light-transmissible region  4011 . The light-transmissible region  4011  is located at a character region or a symbol region of the keycap  401 . The scissors-type connecting element  402  is connected with the keycap  401  and the base plate  45 . The elastic element  403  is penetrated through the scissors-type connecting element  402 . In addition, both ends of the elastic element  403  are contacted with the keycap  401  and the membrane switch circuit member  41 , respectively. Moreover, the membrane switch circuit member  41  is connected with the main circuit board  43  for transmitting first electric power and signals. 
       FIG. 7  is a schematic exploded view illustrating the membrane switch circuit member and the illumination module of the illuminated keyboard according to the second embodiment of the present invention. The membrane switch circuit member  41  comprises an upper wiring board  411 , a partition plate  412  and a lower wiring board  413 . The upper wiring board  411  has plural upper contacts  4111 . The partition plate  412  is disposed under the upper wiring board  411 , and comprises plural partition plate openings  4121  corresponding to the plural upper contacts  4111 . The lower wiring board  413  is disposed under the partition plate  412 , and comprises plural lower contacts  4131  corresponding to the plural upper contacts  4111  and plural light-guiding zones  4132  corresponding to the plural lower contacts  4131 . The plural lower contacts  4131  and the plural upper contacts  4111  are collectively defined as plural key intersections. Each of the light-guiding zones  4132  comprises a light-guiding layer  4132 A. The light-guiding zone  4132  is filled with the corresponding light-guiding layer  4132 A, so that no vacant space is formed in the light-guiding zone  4132 . The light-guiding layers  4132 A are used for guiding the plural light beams to the keycaps  401 , so that the light beams can be transmitted through the light-transmissible regions  4011  of the keycaps  401 . It is noted that portions of the base plate  45  are penetrated through respective openings of the upper wiring board  411 , the partition plate  412  and the lower wiring board  413 . For cleaning the drawing and facilitating observing the light-guiding layers, the openings to be penetrated through by the base plate  45  are not shown in  FIG. 7 . 
     In this embodiment, the light-guiding zones  4132  and the light-guiding layers  4132 A are all circular. The upper wiring board  411  and the partition plate  412  are made of a transparent material such as polycarbonate (PC) or polyethylene (PE). Whereas, the lower wiring board  413  is made of a light-guiding material such as polycarbonate (PC) or polymethylmethacrylate (PMMA). The light-guiding layers  4132 A are formed by printing light-guiding ink on the bottom surface  4133  of the light lower wiring board  413 . The printing process is similar to that of the first embodiment, and is not redundantly described herein. 
     Please refer to  FIGS. 6 and 7 . The illumination module  42  comprises an illumination circuit board  421  and plural light emitting diodes  422 . The illumination circuit board  421  is arranged at the first side of the membrane switch circuit member  41  for providing second electric power to the plural light emitting diodes  422 . The plural light emitting diodes  422  are mounted on the illumination circuit board  421 . By acquiring the second electric power, the plural light emitting diodes  422  are enabled to emit plural light beams. In this embodiment, the plural light emitting diodes  422  are side-view light emitting diodes. In this embodiment, the illumination circuit board  421  is a flexible printed circuit (FPC) board. The reflector  44  is disposed under the membrane switch circuit member  41  for reflecting the plural light beams. The base plate  45  is disposed under the reflector  44  and connected with the scissors-type connecting element  402 . The base plate  45  is used for supporting the keycap  401 , the scissors-type connecting element  402 , the elastic element  403 , the membrane switch circuit member  41  and the reflector  44 . The operations of the illuminated keyboard  4  of this embodiment are similar to those illustrated in the first embodiment, and are not redundantly described herein. 
     The light-guiding layer  4132 A of the illuminated keyboard  4  of this embodiment has benefits similar to the first embodiment. That is, the possibility of abrading the light-guiding layer  4132 A is minimized and the fabricating cost of the illuminated keyboard is reduced. On the other hand, since the light-guiding layer  4132 A is formed on the on the bottom surface  4133  of the light lower wiring board  413  of the membrane switch circuit member  41  in this embodiment, no additional light guide plate is required. Under this circumstance, the internal thickness of the illuminated keyboard  4 , and the internal structure of the illuminated keyboard  4  is simplified. Therefore, the illuminated keyboard  4  is easily assembled and the fabricating cost thereof is reduced. 
     From the above description, the illuminated keyboard of the present invention utilizes integral light-guiding layers to guide the light beams. Since no vacant space is formed in the light-guiding layer, the light-guiding layer is structurally rigid. In other words, when compared with the conventional light-guiding dots, the possibility of abrading the light-guiding layer is largely reduced and the illuminating efficacy of the illuminated keyboard is satisfied. Moreover, the structure of the light-guiding layer is distinguished when compared with the conventional light-guiding dots. Since the light-guiding ink is rarely retained in the stencil during the process of forming the light-guiding layer, the production yield of the light-guiding layer of the present invention is largely increased when compared with the conventional light-guiding dots. 
     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 such modifications and similar structures.