Patent Publication Number: US-9892874-B2

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  (F1˜F12) 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 member  21 , a light guide plate  22 , a backlight module  23 , a supporting 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 member  21 , the supporting 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 member  22 . 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 , so that the keycap  201  can be depressed by the user. The scissors-type connecting element  202  is used for connecting the keycap  201  and the supporting 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 member  21 , respectively. The membrane switch circuit member  21  comprises an upper wiring board  211 , a spacer layer  212 , and a lower wiring board  213 . The upper wiring board  211 , the spacer layer  212  and the lower wiring board  213  are all made of a light-transmissible material. The light-transmissible material is for example polycarbonate (PC) or polyethylene (PE). The upper wiring board  211  has plural upper contacts  2111 . The spacer layer  212  is disposed under the upper wiring board  211 , and comprises plural perforations  2121  corresponding to the plural upper contacts  2111 . The lower wiring board  213  is disposed under the spacer layer  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 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 member  21  for providing 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 supporting plate  24  is arranged between the membrane switch circuit member  21  and the light guide plate  22  for supporting the keycap  201 , the scissors-type connecting element  202 , the elastic element  203  and the membrane switch circuit member  21 . 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 supporting plate  24  comprises plural supporting plate openings  241 . The plural supporting 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 member  21  is made of the light-transmissible material, the plural light beams B can be transmitted through the membrane switch circuit member  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 supporting plate openings  241  and the membrane switch circuit member  21  and directed to the plural light-outputting zones  2011 , thereby illuminating the character region or the symbol region of the keycap  201 . Under this circumstance, the illuminating function is achieved. 
     While the plural light beams B are projected to the light guide plate  22 , the plural light beams B are radiated from the light-emitting elements  232 . Consequently, portions of the plural light beams B are introduced into the light guide plate  22  at a larger incident angle and unable to be subjected to total internal reflection within the light guide plate  22 . The portions of the plural light beams B unable to be subjected to total internal reflection are transferred through the light guide plate  22  and projected upwardly. Under this circumstance, bright spots are usually generated at the locations near the light-emitting elements  232 . The bright spots are also referred as bright bands or bright areas. The occurrence of the bright spots indicates that the light beams are very centralized and the illuminating efficacy is highly centralized. In other words, the luminous uniformity of the conventional luminous keyboard  2  is unsatisfied. 
     Therefore, there is a need of providing a luminous keyboard with enhanced luminous uniformity. 
     SUMMARY OF THE INVENTION 
     An object of the present invention provides a luminous keyboard with enhanced luminous uniformity. 
     In accordance with an aspect of the present invention, there is provided a luminous keyboard. The luminous keyboard includes a keypad module, at least one light-emitting element, a light guide plate and a reflecting plate. The keypad module is exposed to a top surface of the luminous keyboard. The at least one light-emitting element is disposed under the keypad module, and emits at least one light beam. The light guide plate is disposed under the keypad module. The at least one light beam is subjected to total internal reflection within the light guide plate and guided to the keypad module by the light guide plate. The reflecting plate is disposed over or under the light guide plate. A portion of the at least one light beam that is not subjected to total internal reflection within the light guide plate is reflected by the reflecting plate. The reflecting plate has at least one light amount control structure. The at least one light amount control structure is disposed on a top surface or a bottom surface of the reflecting plate and located near the corresponding light-emitting element. When the portion of the at least one light beam that is not subjected to total internal reflection within the light guide plate is transferred through the at least one light amount control structure, a reflected fraction of the at least one light beam is reduced by the at least one light amount control structure. 
     In accordance with another aspect of the present invention, there is provided a luminous keyboard. The luminous keyboard includes a keypad module, at least one light-emitting element, a light guide plate and a light absorption plate. The keypad module is exposed to a top surface of the luminous keyboard. The at least one light-emitting element is disposed under the keypad module, and emits at least one light beam. The light guide plate is disposed under the keypad module. The at least one light beam is subjected to total internal reflection within the light guide plate and guided to the keypad module by the light guide plate. The light absorption plate is disposed over or under the light guide plate. A portion of the at least one light beam that is not subjected to total internal reflection within the light guide plate is absorbed by the light absorption plate. The light absorption plate has at least one light amount control structure. The at least one light amount control structure is disposed on a top surface or a bottom surface of the light absorption plate and located near the corresponding light-emitting element. When the portion of the at least one light beam that is not subjected to total internal reflection within the light guide plate is transferred through the at least one light amount control structure, a reflected fraction of the at least one light beam is reduced by the at least one light amount control structure. 
     From the above descriptions, the present invention provides a luminous keyboard. The luminous keyboard has a reflecting plate (or a light absorption plate) with a special structure. In particular, plural light amount control structures with many variant examples are disposed on the reflecting plate (or the light absorption plate), and the light amount control structures are arranged between a light guide plate and the reflecting plate (or the light absorption plate). That is, the light amount control structures are located at the reflecting path of the light beams. When the portions of the light beams that are not subjected to total internal reflection within the light guide plate are reflected by the reflecting plate (or the light absorption plate), the reflected fraction of the light beams is reduced by the light amount control structure. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. For further reducing the reflected fraction of the light beams, the light amount control structures of the luminous keyboard may have different lengths according to the practical requirements. 
     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 view illustrating the structure of a luminous keyboard according to a second embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a third embodiment of the present invention; 
         FIG. 6  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fourth embodiment of the present invention; 
         FIG. 7  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fifth embodiment of the present invention; 
         FIG. 8  is a schematic top view illustrating a portion of the luminous keyboard of the fifth embodiment; 
         FIG. 9  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a sixth embodiment of the present invention; 
         FIG. 10  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a seventh embodiment of the present invention; 
         FIG. 11  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eighth embodiment of the present invention; 
         FIG. 12  is a schematic top view illustrating a portion of the luminous keyboard of the eighth embodiment; 
         FIG. 13  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a ninth embodiment of the present invention; 
         FIG. 14  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a tenth embodiment of the present invention; 
         FIG. 15  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eleventh embodiment of the present invention; 
         FIG. 16  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a twelfth embodiment of the present invention; 
         FIG. 17  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a thirteenth embodiment of the present invention; 
         FIG. 18  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fourteenth embodiment of the present invention; 
         FIG. 19  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fifteenth embodiment of the present invention; 
         FIG. 20  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a sixteenth embodiment of the present invention; 
         FIG. 21  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a seventeenth embodiment of the present invention; and 
         FIG. 22  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eighteenth 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 a keypad module  30 A, a supporting plate  31 A, plural light-emitting elements  32 A, an illumination circuit board  33 A, a light guide plate  34 A, a reflecting plate  35 A and a light-shading plate  36 A. For clarification and brevity, only one light-emitting element  32 A is shown in the drawing. The keypad module  30 A is exposed to a top surface of the luminous keyboard  3 A. The keypad module  30 A comprises plural keycaps  301 A, plural connecting elements  302 A, plural elastic elements  303 A and a switch circuit member  304 A. Each of the plural keycaps  301 A, the corresponding connecting element  302 A and the corresponding elastic element  303 A are collaboratively defined as a key. Each keycap  301 A has a light-outputting zone  305 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 switch circuit member  304 A. The switch circuit member  304 A is disposed under the plural keys. When the switch circuit member  304 A is triggered by the plural elastic elements  303 A, plural key signals are correspondingly generated. The structure of the switch circuit member  304 A is similar to that of the conventional membrane switch circuit member, and is not redundantly described herein. It is noted that the switch circuit member  304 A is not limited to the membrane switch circuit member. 
     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 switch circuit member  304 A is depressed by the plural elastic elements  303 A through the plural keys. In another embodiment, the connecting elements are non-scissors connecting element for controlling movements of the keys. In a further embodiment, the keycaps are moved upwardly or downwardly in response to magnetic forces. 
     Please refer to  FIG. 3  again. The plural light-emitting elements  32 A are disposed on the illumination circuit board  33 A, and disposed under the keypad module  30 A. Moreover, the plural light-emitting elements  32 A are partially inserted into the light guide plate  34 A. The plural light-emitting elements  32 A are used for emitting plural light beams B, and the plural light beams B are laterally introduced into the light guide plate  34 A. The light guide plate  34 A is disposed under the keypad module  30 A. The plural light beams B are subjected to total internal reflection within the light guide plate  34 A, and thus the plural light beams B are guided to the keypad module  30 A by the light guide plate  34 A. The light guide plate  34 A comprises plural light-guiding structures  341 A. Each light-guiding structure  341 A is aligned with the corresponding light-outputting zone  305 A. The plural light beams B can be guided to the corresponding light-outputting zones  305 A by the light-guiding structures  341 A so as to illuminate the corresponding keys. In this embodiment, the plural light-emitting elements  32 A are side-view light emitting diodes, and the illumination circuit board  33 A is a flexible printed circuit (FPC). In an embodiment, the light-guiding structure  341 A is a one of a light-guiding microstructure, a light-guiding dot, a light-guiding ink and a light-guiding texturing structure. 
     The reflecting plate  35 A is disposed under the light guide plate  34 A. The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 A can be reflected by the reflecting plate  35 A. Consequently, the utilization efficiency of the portions of the plural light beams B that are not subjected to total internal reflection will be enhanced. Moreover, the reflecting plate  35 A comprises plural light amount control structures  351 A corresponding to the plural light-emitting elements  32 A. For brevity, only one light amount control structure  351 A is shown in the drawing. The light amount control structures  351 A are disposed on a top surface of the reflecting plate  35 A, and located near the corresponding light-emitting elements  32 A. That is, the plural light amount control structures  351 A are arranged between the reflecting plate  35 A and the light guide plate  34 A, and located at specified regions near the corresponding light-emitting elements  32 A. After the portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 A are transferred through the light amount control structures  351 A, the reflected fraction of the light beams B is reduced. 
     The light-shading plate  36 A is disposed over the light guide plate  34 A and the plural light-emitting elements  32 A. By means of the light-shading plate  36 A, the portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 A will not be directly projected to the keypad module  30 A. 
     In this embodiment, the plural light amount control structures  351 A are made of light absorption material. Preferably, the light absorption material is a composite material of a high refractive index material and a low refractive index material, wherein the low refractive index material is covered by the high refractive index material. Alternatively, the light absorption material is selected from a surface plasmon material or a metamaterial. 
     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 illumination of the luminous keyboard  3 A will be illustrated as follows. Please refer to  FIG. 3  again. When the plural light-emitting elements  32 A emit the plural light beams B, portions of the light beams B are laterally introduced into the light guide plate  34 A and subjected to total internal reflection within the light guide plate  34 A. The light beams B can be guided to the corresponding light-outputting zones  305 A by the light-guiding structures  341 A so as to illuminate the light-outputting zones  305 A. On the other hand, other portions of the plural light beams B are laterally introduced into the light guide plate  34 A at a larger incident angle and unable to be subjected to total internal reflection within the light guide plate  34 A, and thus shaded by the light-shading plate  36 A and reflected to the light guide plate  34 A. The portions of the plural light beams B reflected by the second reflecting plate  36 A are transmitted through the light guide plate  34 A, and then transferred through the light amount control structures  351 A. 
     When the light beams B are transferred through the light amount control structures  351 A, portions of the light beams B are absorbed by the light amount control structures  351 A. The remaining small portions of the light beams B are transmitted through the light amount control structures  351 A and reflected to the light guide plate  34 A by the underlying reflecting plate  35 A, and no longer shaded by the light-shading plate  36 A. Consequently, the remaining small portions of the light beams B are projected to the keycaps  301 A and not directly projected to the light-outputting zones  305 A. Since portions of the light beams B at the larger incident angle are absorbed by the light amount control structures  351 A, only the remaining small portions of the light beams B are reflected to the keycaps  301 A. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. Under this circumstance, the luminous uniformity is enhanced. 
     The present invention further provides a luminous keyboard of a second embodiment, which is distinguished from the above embodiment.  FIG. 4  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a second embodiment of the present invention. As shown in  FIG. 4 , the luminous keyboard  3 B comprises a keypad module  30 B, a supporting plate  31 B, plural light-emitting elements  32 B, an illumination circuit board  33 B, a light guide plate  34 B and a reflecting plate  35 B. For clarification and brevity, only one light-emitting element  32 B is shown in the drawing. The keypad module  30 B comprises plural keycaps  301 B, plural connecting elements  302 B, plural elastic elements  303 B and a switch circuit member  304 B. Each keycap  301 B has a light-outputting zone  305 B. The light guide plate  34 B comprises plural light-guiding structures  341 B. Each light-guiding structure  341 B is aligned with the corresponding light-outputting zone  305 B. Moreover, the reflecting plate  35 B comprises plural light amount control structures  351 B corresponding to the plural light-emitting elements  32 B. For brevity, only one light amount control structure  351 B is shown in the drawing. The components of the luminous keyboard  3 B of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the luminous keyboard  3 B of this embodiment is not equipped with the light-shading plate and the arrangements of the light-emitting elements  32 B and the illumination circuit board  33 B are distinguished. 
     In the embodiment of  FIG. 4 , the light-emitting elements  32 B are inverted, and inserted into the light guide plate  34 B through an upper portion of the light guide plate  34 B. In addition, the illumination circuit board  33 B supporting the light-emitting elements  32 B is also inverted and arranged between the supporting plate  31 B and the light guide plate  34 B. Since the illumination circuit board  33 B is disposed over the light guide plate  34 B, the illumination circuit board  33 B also has the function of shading the light beams B. Consequently, the luminous keyboard  3 B of this embodiment is not equipped with the light-shading plate. That is, the overall thickness of the luminous keyboard  3 B is reduced, and the fabricating cost of the luminous keyboard  3 B is reduced to meet the economic benefit. The illumination of the luminous keyboard  3 B is similar to the illumination of the luminous keyboard  3 A of the first embodiment, and is not redundantly described herein. 
     The present invention further provides a luminous keyboard of a third embodiment, which is distinguished from the above embodiments.  FIG. 5  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a third embodiment of the present invention. As shown in  FIG. 5 , the luminous keyboard  3 C comprises a keypad module  30 C, a supporting plate  31 C, plural light-emitting elements  32 C, an illumination circuit board  33 C, a light guide plate  34 C, a first reflecting plate  35 C and a second reflecting plate  36 C. For clarification and brevity, only one light-emitting element  32 C is shown in the drawing. The keypad module  30 C comprises plural keycaps  301 C, plural connecting elements  302 C, plural elastic elements  303 C and a switch circuit member  304 C. Each keycap  301 C has a light-outputting zone  305 C. The light guide plate  34 C comprises plural light-guiding structures  341 C. Each light-guiding structure  341 C is aligned with the corresponding light-outputting zone  305 C. Moreover, the first reflecting plate  35 C comprises plural light amount control structures  351 C corresponding to the plural light-emitting elements  32 C. For brevity, only one light amount control structure  351 C is shown in the drawing. The components of the luminous keyboard  3 C of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the luminous keyboard  3 C of this embodiment is not equipped with the light-shading plate, and the luminous keyboard  3 C further comprises the second reflecting plate  36 C in replace of the light-shading plate. 
     The second reflecting plate  36 C is disposed over the light guide plate  34 C. That is, the second reflecting plate  36 C and the first reflecting plate  35 C are respectively disposed over and under the light guide plate  34 C. The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 C are reflected by the first reflecting plate  35 C and the second reflecting plate  36 C. The second reflecting plate  36 C further comprises plural openings  361 C. Each opening  361 C is aligned with the corresponding light-outputting zone  305 C. Since the second reflecting plate  36 C has the functions of shading and reflecting the light beams B, the luminous keyboard  3 C of this embodiment is not equipped with the light-shading plate. 
     The illumination of the luminous keyboard  3 C will be illustrated as follows. Please refer to  FIG. 5  again. When the plural light-emitting elements  32 C emit the plural light beams B, portions of the light beams B are laterally introduced into the light guide plate  34 C and subjected to total internal reflection within the light guide plate  34 C. The light beams B can be guided to the corresponding light-outputting zones  305 C by the light-guiding structures  341 C so as to illuminate the light-outputting zones  305 C. On the other hand, other portions of the plural light beams B are laterally introduced into the light guide plate  34 C at a larger incident angle and unable to be subjected to total internal reflection within the light guide plate  34 C, and thus reflected to the light guide plate  34 C by the second reflecting plate  36 C. The portions of the plural light beams B reflected by the second reflecting plate  36 C are transmitted through the light guide plate  34 C, and then transferred through the light amount control structures  351 C. When the light beams B are transferred through the light amount control structures  351 C, portions of the light beams B are absorbed by the light amount control structures  351 C. The remaining small portions of the light beams B are transmitted through the light amount control structure  351 C and reflected by the underlying first reflecting plate  35 C. 
     Then, the remaining small portions of the light beams B are alternately reflected by the first reflecting plate  35 C and the second reflecting plate  36 C. Since portions of the light beams B are absorbed by the light amount control structures  351 C during the reflecting process, only the remaining small portions of the light beams B are projected to the keycaps  301 C through the openings  361 C. Since the light beams B are alternately reflected by the overlying second reflecting plate  36 C and the underlying first reflecting plate  35 C of the light guide plate  34 D and the light amount control structures  351 C are located at the reflection path of the light beams B, the reflected fraction of the light beams B is reduced. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. 
     The present invention further provides a luminous keyboard of a fourth embodiment, which is distinguished from the above embodiments.  FIG. 6  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fourth embodiment of the present invention. As shown in  FIG. 6 , the luminous keyboard  3 D comprises a keypad module  30 D, a supporting plate  31 D, plural light-emitting elements  32 D, an illumination circuit board  33 D, a light guide plate  34 D, a first reflecting plate  35 D and a second reflecting plate  36 D. For clarification and brevity, only one light-emitting element  32 D is shown in the drawing. The keypad module  30 D comprises plural keycaps  301 D, plural connecting elements  302 D, plural elastic elements  303 D and a switch circuit member  304 D. Each keycap  301 D has a light-outputting zone  305 D. The light guide plate  34 D comprises plural light-guiding structures  341 D. Each light-guiding structure  341 D is aligned with the corresponding light-outputting zone  305 D. The second reflecting plate  36 D further comprises plural openings  361 D. Each opening  361 D is aligned with the corresponding light-outputting zone  305 D. The components of the luminous keyboard  3 D of this embodiment which are similar to the luminous keyboard  3 C of the third embodiment are not redundantly described herein. In comparison with the third embodiment, the first reflecting plate  35 D of the luminous keyboard  3 D is not equipped with the light amount control structures. Whereas, the second reflecting plate  36 D comprises plural light amount control structures  362 D. For brevity, only one light amount control structure  362 D is shown in the drawing. 
     The structures of the luminous keyboard  3 D of this embodiment are somewhat different from the structures of the luminous keyboard  3 C of the third embodiment. However, the plural light amount control structures  362 D are arranged between the second reflecting plate  36 D and the light guide plate  34 D and located near the plural light-emitting elements  32 D. That is, the light amount control structures  362 D are still located at the reflection path of the light beams B that are alternately reflected by the first reflecting plate  35 D and the second reflecting plate  36 D. Consequently, the luminous uniformity of the luminous keyboard  3 D is also enhanced. The illumination of the luminous keyboard  3 D is similar to the illumination of the luminous keyboard  3 C of the third embodiment, and is not redundantly described herein. 
     The present invention further provides a luminous keyboard of a fifth embodiment, which is distinguished from the above embodiments.  FIG. 7  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fifth embodiment of the present invention. As shown in  FIG. 7 , the luminous keyboard  3 E comprises a keypad module  30 E, a supporting plate  31 E, plural light-emitting elements  32 E, an illumination circuit board  33 E, a light guide plate  34 E, a first reflecting plate  35 E and a second reflecting plate  36 E. For clarification and brevity, only one light-emitting element  32 E is shown in the drawing. The keypad module  30 E comprises plural keycaps  301 E, plural connecting elements  302 E, plural elastic elements  303 E and a switch circuit member  304 E. Each keycap  301 E has a light-outputting zone  305 E. The light guide plate  34 E comprises plural light-guiding structures  341 E. Each light-guiding structure  341 E is aligned with the corresponding light-outputting zone  305 E. The second reflecting plate  36 E further comprises plural openings  361 E. Each opening  361 E is aligned with the corresponding light-outputting zone  305 E. The components of the luminous keyboard  3 E of this embodiment which are similar to the luminous keyboard  3 C of the third embodiment are not redundantly described herein. In comparison with the third embodiment, the second reflecting plate  36 E of the luminous keyboard  3 E comprises plural second light amount control structures  362 E (only one is shown in the drawing), and the first reflecting plate  35 E comprises plural first light amount control structures  351 E (only one is shown in the drawing). 
     Please refer to  FIG. 7  again. The plural first light amount control structures  351 E are arranged between the first reflecting plate  35 E and the light guide plate  34 E. That is, the first light amount control structures  351 E are disposed on a top surface of the first reflecting plate  35 E, and located at specified regions near the corresponding light-emitting elements  32 E. The plural second light amount control structures  362 E are arranged between the second reflecting plate  36 E and the light guide plate  34 E. That is, the second light amount control structures  362 E are disposed on a bottom surface of the second reflecting plate  36 E, and located at specified regions near the corresponding light-emitting elements  32 E. 
     Please refer to  FIGS. 7 and 8 .  FIG. 8  is a schematic top view illustrating a portion of the luminous keyboard of the fifth embodiment. In  FIG. 8 , the light-emitting elements  32 E, the first light amount control structures  351 E and the second light amount control structures  362 E are shown. The first light amount control structures  351 E are overlapped with the corresponding second light amount control structures  362 E. The first light amount control structures  351 E are longer than the corresponding second light amount control structures  362 E. Moreover, the first light amount control structures  351 E and the second light amount control structures  362 E are asymmetrical structures. In  FIG. 8 , two light-emitting elements  32 E are shown. Since two light-emitting elements  32 E emit the light beams, the area between the two light-emitting elements  32 E has higher light amount of the light beams B. In this embodiment, the first light amount control structures  351 E and the second light amount control structures  362 E at the area between the two light-emitting elements  32 E have stronger light-absorption capability. Moreover, the first light amount control structures  351 E and the second light amount control structures  362 E are asymmetrical structures. In other words, the wider part of the first light amount control structure  351 E and the wider part of the adjacent second light amount control structures  362 E are located at the area between the two light-emitting elements  32 E in order to absorb more light amount of the light beams B. Consequently, the problem of generating bright spots will be diminished. 
     The present invention further provides a luminous keyboard of a sixth embodiment, which is distinguished from the above embodiments.  FIG. 9  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a sixth embodiment of the present invention. As shown in  FIG. 9 , the luminous keyboard  3 F comprises a keypad module  30 F, a supporting plate  31 F, plural light-emitting elements  32 F, an illumination circuit board  33 F, a light guide plate  34 F, a reflecting plate  35 F, a light-shading plate  36 F and plural light absorption structures  37 F. For clarification and brevity, only one light-emitting element  32 F and one light absorption structure  37 F are shown in the drawing. The keypad module  30 F comprises plural keycaps  301 F, plural connecting elements  302 F, plural elastic elements  303 F and a switch circuit member  304 F. Each keycap  301 F has a light-outputting zone  305 F. The light guide plate  34 F comprises plural light-guiding structures  341 F. Each light-guiding structure  341 F is aligned with the corresponding light-outputting zone  305 F. Moreover, the reflecting plate  35 F comprises plural light amount control structures  351 F corresponding to the plural light-emitting elements  32 F. For brevity, only one light amount control structure  351 F is shown in the drawing. The components of the luminous keyboard  3 F of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the following two aspects of the luminous keyboard  3 F of this embodiment are distinguished. Firstly, the plural light amount control structures  351 F of the luminous keyboard  3 F are made of anti-reflection materials, and the plural light amount control structures  351 F are deposited on a top surface of the reflecting plate  35 F. Secondly, the luminous keyboard  3 F of this embodiment further comprises the plural light absorption structures  37 F. 
     The operating principles of the anti-reflection material will be described as follows. When the light beams transferred from a first transparent object to a second transparent object with a different refractive index, the light beams are reflected by the interface between the first object and the second object. In case that the difference between the refractive indexes of these two objects is higher, the intensity of the reflective light beams is stronger. For achieving the anti-reflecting function, the material with the refractive index close to air is selected as the anti-reflection material. In an embodiment, the anti-reflection material is magnesium fluoride (MgF2), silicon dioxide (SiO2), Teflon, or any other appropriate material. 
     The plural light amount control structures  351 F are not used for absorbing the light beams B. When the light beams B are projected on the plural light amount control structures  351 F, greater portions of the light beams B are transmitted through the plural light amount control structures  351 F, and only smaller portions of the light beams are reflected. Consequently, the reflected fraction of the light beams B is reduced. In this embodiment, the light absorption structures  37 F are disposed on the reflecting plate  35 F. Moreover, the light absorption structures  37 F and the light amount control structures  351 F are disposed on opposite surfaces of the reflecting plate  35 F. That is, the light absorption structures  37 F are disposed on a bottom surface of the reflecting plate  35 F. Consequently, the greater portions of the light beams B introduced into the light amount control structures  351 F will be absorbed by the light absorption structure  37 F. Consequently, the amount of the light beams reflected by the reflecting plate  35 F is further reduced. 
     The present invention further provides a luminous keyboard of a seventh embodiment, which is distinguished from the above embodiments.  FIG. 10  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a seventh embodiment of the present invention. As shown in  FIG. 10 , the luminous keyboard  3 G comprises a keypad module  30 G, a supporting plate  31 G, plural light-emitting elements  32 G, an illumination circuit board  33 G, a light guide plate  34 G, a first reflecting plate  35 G, a second reflecting plate  36 G and plural light absorption structures  37 G. For clarification and brevity, only one light-emitting element  32 G is shown in the drawing. The keypad module  30 G comprises plural keycaps  301 G, plural connecting elements  302 G, plural elastic elements  303 G and a switch circuit member  304 G. Each keycap  301 G has a light-outputting zone  305 G. The light guide plate  34 G comprises plural light-guiding structures  341 G. Each light-guiding structure  341 G is aligned with the corresponding light-outputting zone  305 G. The second reflecting plate  36 G further comprises plural openings  361 G. Each opening  361 G is aligned with the corresponding light-outputting zone  305 G. Moreover, the first reflecting plate  35 G comprises plural light amount control structures  351 G corresponding to the plural light-emitting elements  32 G. For brevity, only one light amount control structure  351 G is shown in the drawing. The components of the luminous keyboard  3 G of this embodiment which are similar to the luminous keyboard  3 F of the sixth embodiment are not redundantly described herein. In comparison with the sixth embodiment, the luminous keyboard  3 G of this embodiment is not equipped with the light-shading plate, and the luminous keyboard  3 G further comprises the second reflecting plate  36 G in replace of the light-shading plate. 
     The second reflecting plate  36 G is disposed over the light guide plate  34 G. That is, the second reflecting plate  36 G and the first reflecting plate  35 G are respectively disposed over and under the light guide plate  34 G. The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 G are reflected by the first reflecting plate  35 G and the second reflecting plate  36 G. The second reflecting plate  36 G further comprises plural openings  361 G. Each opening  361 G is aligned with the corresponding light-outputting zone  305 G. Since the second reflecting plate  36 G has the functions of shading and reflecting the light beams B, the luminous keyboard  3 G of this embodiment is not equipped with the light-shading plate. 
     The structure of the luminous keyboard  3 G of this embodiment may be modified. For example, in a variant example, plural light amount control structures are disposed on a bottom surface of the second reflecting plate, and plural light absorption structures are disposed on a top surface of the second reflecting plate. In another variant example, the plural light-emitting elements and the illumination circuit board are inverted. By changing the locations of some components, different stack structures of the luminous keyboard can be produced. These stack structures can diminish the problem of generating bright spots. 
     The present invention further provides a luminous keyboard of an eighth embodiment, which is distinguished from the above embodiments.  FIG. 11  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eighth embodiment of the present invention. As shown in  FIG. 11 , the luminous keyboard  3 H comprises a keypad module  30 H, a supporting plate  31 H, plural light-emitting elements  32 H, an illumination circuit board  33 H, a light guide plate  34 H, a first reflecting plate  35 H, a second reflecting plate  36 H and plural light absorption structures  37 H. For clarification and brevity, only one light-emitting element  32 H is shown in the drawing. The keypad module  30 H comprises plural keycaps  301 H, plural connecting elements  302 H, plural elastic elements  303 H and a switch circuit member  304 H. Each keycap  301 H has a light-outputting zone  305 H. The light guide plate  34 H comprises plural light-guiding structures  341 H. Each light-guiding structure  341 H is aligned with the corresponding light-outputting zone  305 H. The second reflecting plate  36 H further comprises plural openings  361 H. Each opening  361 H is aligned with the corresponding light-outputting zone  305 H. The components of the luminous keyboard  3 H of this embodiment which are similar to the luminous keyboard  3 G of the seventh embodiment are not redundantly described herein. In comparison with the seventh embodiment, the first reflecting plate  35 H comprises plural first light amount control structures  351 H (only one is shown in the drawing), and the second reflecting plate  36 H of the luminous keyboard  3 H comprises plural second light amount control structures  362 H (only one is shown in the drawing). 
     Please refer to  FIG. 11  again. The plural first light amount control structures  351 H are arranged between the first reflecting plate  35 H and the light guide plate  34 H. That is, the first light amount control structures  351 H are disposed on a top surface of the first reflecting plate  35 H, and located at specified regions near the corresponding light-emitting elements  32 H. The plural second light amount control structures  362 H are arranged between the second reflecting plate  36 H and the light guide plate  34 H. That is, the second light amount control structures  362 H are disposed on a bottom surface of the second reflecting plate  36 H, and located at specified regions near the corresponding light-emitting elements  32 H. 
     Please refer to  FIGS. 11 and 12 .  FIG. 12  is a schematic top view illustrating a portion of the luminous keyboard of the eighth embodiment. In  FIG. 12 , the light-emitting elements  32 H, the first light amount control structures  351 H and the second light amount control structures  362 H are shown. The first light amount control structures  351 H are not overlapped with the corresponding second light amount control structures  362 H. Moreover, the first light amount control structures  351 H and the second light amount control structures  362 H are asymmetrical structures. In  FIG. 12 , two light-emitting elements  32 H are shown. Since two light-emitting elements  32 H emit the light beams, the area between the two light-emitting elements  32 H has higher light amount of the light beams B. In this embodiment, the first light amount control structures  351 H and the second light amount control structures  362 H at the area between the two light-emitting elements  32 H have stronger light-absorption capability. Moreover, the first light amount control structures  351 H and the second light amount control structures  362 H are asymmetrical structures. In other words, the wider part of the first light amount control structure  351 E and the wider part of the adjacent second light amount control structures  362 E are located at the area between the two light-emitting elements  32 H in order to absorb more light amount of the light beams B. Consequently, the problem of generating bright spots will be diminished. 
     The present invention further provides a luminous keyboard of a ninth embodiment, which is distinguished from the above embodiments.  FIG. 13  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a ninth embodiment of the present invention. As shown in  FIG. 13 , the luminous keyboard  3 I comprises a keypad module  30 I, a supporting plate  31 I, plural light-emitting elements  32 I, an illumination circuit board  33 I, a light guide plate  34 I, a reflecting plate  35 I and a light-shading plate  36 I. For clarification and brevity, only one light-emitting element  32 I is shown in the drawing. The keypad module  30 I comprises plural keycaps  301 I, plural connecting elements  302 I, plural elastic elements  303 I and a switch circuit member  304 I. Each keycap  301 I has a light-outputting zone  305 I. The light guide plate  34 I comprises plural light-guiding structures  341 I. Each light-guiding structure  341 I is aligned with the corresponding light-outputting zone  305 I. Moreover, the reflecting plate  35 I comprises plural light amount control structures  351 I corresponding to the plural light-emitting elements  32 I. For brevity, only one light amount control structure  351 I is shown in the drawing. The components of the luminous keyboard  3 I of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the light amount control structures  351 I of the luminous keyboard  3 I of this embodiment have respective texturing structures  352 I. 
     Please refer to  FIG. 13  again. The light amount control structures  351 I are arranged between the reflecting plate  35 I and the light guide plate  34 I, and disposed on a top surface of the reflecting plate  35 I. That is, the light amount control structures  351 I are located at specified regions near the corresponding light-emitting elements  32 I. The texturing structures  352 I are formed on the top surfaces of the corresponding light amount control structures  351 I. By the texturing structures  352 I, the number of times that the light beams B are reflected is increased, and the reflected fraction of the light beams B is reduced. When the portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 I are projected to the light amount control structures  351 I, the plural light beams B are reflected for many times by the texturing structures  352 I because of the uneven surfaces of the texturing structures  352 I. In particular, when the light beams B are projected on the texturing structures  352 I at a first time, portions of the light beams B are reflected by the texturing structures  352 I and thus projected on the texturing structures  352 I at a second time. The remaining portions of the light beams that are not reflected are absorbed by the light amount control structures  351 I. The operations of the reflected light beams projected on the texturing structures  352 I at the second time are similar to the operations of the light beams projected on the texturing structures  352 I at the first time. Consequently, less amount of the light beams B is reflected by the texturing structures  352 I. In other words, after the light beams B are projected on the texturing structures  352 I for many times, the number of times that the light beams B are reflected is increased and the reflected fraction of the light beams B is reduced. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. Under this circumstance, the luminous uniformity is enhanced. 
     The present invention further provides a luminous keyboard of a tenth embodiment, which is distinguished from the above embodiments.  FIG. 14  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a tenth embodiment of the present invention. As shown in  FIG. 14 , the luminous keyboard  3 J comprises a keypad module  30 J, a supporting plate  31 J, plural light-emitting elements  32 J, an illumination circuit board  33 J, a light guide plate  34 J, a first reflecting plate  35 J and a second reflecting plate  36 J. For clarification and brevity, only one light-emitting element  32 J is shown in the drawing. The keypad module  30 J comprises plural keycaps  301 J, plural connecting elements  302 J, plural elastic elements  303 J and a switch circuit member  304 J. Each keycap  301 J has a light-outputting zone  305 J. The light guide plate  34 J comprises plural light-guiding structures  341 J. Each light-guiding structure  341 J is aligned with the corresponding light-outputting zone  305 E. The second reflecting plate  36 J further comprises plural openings  361 J. Each opening  361 J is aligned with the corresponding light-outputting zone  305 J. The components of the luminous keyboard  3 J of this embodiment which are similar to the luminous keyboard  3 I of the ninth embodiment are not redundantly described herein. In comparison with the ninth embodiment, the following two aspects of the luminous keyboard  3 J of this embodiment are distinguished. Firstly, the luminous keyboard  3 J of this embodiment is not equipped with the light-shading plate, and the second reflecting plate  36 J can replace the light-shading plate. Secondly, the second reflecting plate  36 J of the luminous keyboard  3 J comprises plural openings  361 J and plural second light amount control structures  362 J (only one is shown in the drawing). 
     As shown in  FIG. 14 , plural first light amount control structures  351 J are arranged between the first reflecting plate  35 J and the light guide plate  34 J, and disposed on a top surface of the first reflecting plate  35 J. That is, the first light amount control structures  351 J are located at specified regions near the corresponding light-emitting elements  32 J. The plural second light amount control structures  362 J are arranged between the second reflecting plate  36 J and the light guide plate  34 J. That is, the second light amount control structures  362 J are disposed on a bottom surface of the second reflecting plate  36 J, and located at specified regions near the corresponding light-emitting elements  32 J. Moreover, the first light amount control structures  351 J have respective first texturing structures  352 J, and the second light amount control structures  362 J have respective second texturing structures  363 J. The first light amount control structures  351 J are not overlapped with the corresponding second light amount control structures  362 J. The propagating processes of the light beams B through the second light amount control structures  362 J and the second texturing structures  363 J are similar to those of the luminous keyboard  3 I of the ninth embodiment, and are not redundantly described herein. 
     The structure of the luminous keyboard  3 J of this embodiment may be modified. For example, in a variant example, only the first light amount control structures are disposed on the top surface of the first reflecting plate, or only the second light amount control structures are disposed on the bottom surface of the second reflecting plate. That is, only one reflecting plate has the light amount control structures. In another variant example, the plural light-emitting elements and the illumination circuit board are inverted. By changing the locations of some components, different stack structures of the luminous keyboard can be produced. These stack structures can diminish the problem of generating bright spots. 
     The present invention further provides a luminous keyboard of an eleventh embodiment, which is distinguished from the above embodiment.  FIG. 15  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eleventh embodiment of the present invention. As shown in  FIG. 15 , the luminous keyboard  3 K comprises a keypad module  30 K, a supporting plate  31 K, plural light-emitting elements  32 K, an illumination circuit board  33 K, a light guide plate  34 K, a reflecting plate  35 K and a light-shading plate  36 K. For clarification and brevity, only one light-emitting element  32 K is shown in the drawing. The keypad module  30 K comprises plural keycaps  301 K, plural connecting elements  302 K, plural elastic elements  303 K and a switch circuit member  304 K. Each keycap  301 K has a light-outputting zone  305 K. The light guide plate  34 K comprises plural light-guiding structures  341 K. Each light-guiding structure  341 K is aligned with the corresponding light-outputting zone  305 K. Moreover, the reflecting plate  35 K comprises plural light amount control structures  351 K corresponding to the plural light-emitting elements  32 K. For brevity, only one light amount control structure  351 K is shown in the drawing. The components of the luminous keyboard  3 K of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the light amount control structures  351 K of the luminous keyboard  3 K of this embodiment are texturing structures, which are integrally formed with the reflecting plate  35 K. 
     Please refer to  FIG. 15  again. The light amount control structures  351 K are arranged between the reflecting plate  35 K and the light guide plate  34 K, and disposed on a top surface of the reflecting plate  35 K. That is, the light amount control structures  351 K are located at specified regions near the corresponding light-emitting elements  32 K. By the light amount control structures  351 K, the number of times that the light beams B are reflected is increased, and the reflected fraction of the light beams B is reduced. In other words, the light amount control structures  351 K are not additional light absorption materials or additional anti-reflection materials on the reflecting plate  35 K. Instead, the light amount control structures  351 K are texturing structures that are formed by machining the reflecting plate  35 K. Although the structures of the luminous keyboard  3 K of this embodiment are somewhat different from the structures of the luminous keyboards of the above embodiments, the luminous keyboard  3 K also has enhanced luminous uniformity. The illumination of the luminous keyboard  3 K is similar to the illumination of the luminous keyboards of the above embodiments, and is not redundantly described herein. 
     The present invention further provides a luminous keyboard of a twelfth embodiment, which is distinguished from the above embodiment.  FIG. 16  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a twelfth embodiment of the present invention. As shown in  FIG. 16 , the luminous keyboard  3 L comprises a keypad module  30 L, a supporting plate  31 L, plural light-emitting elements  32 L, an illumination circuit board  33 L, a light guide plate  34 L, a reflecting plate  35 L and a light-shading plate  36 L. For clarification and brevity, only one light-emitting element  32 L is shown in the drawing. The keypad module  30 L comprises plural keycaps  301 L, plural connecting elements  302 L, plural elastic elements  303 L and a switch circuit member  304 L. Each keycap  301 L has a light-outputting zone  305 L. The light guide plate  34 L comprises plural light-guiding structures  341 L. Each light-guiding structure  341 L is aligned with the corresponding light-outputting zone  305 L. Moreover, the reflecting plate  35 L comprises plural light amount control structures  351 L corresponding to the plural light-emitting elements  32 L. For brevity, only one light amount control structure  351 L is shown in the drawing. The components of the luminous keyboard  3 L of this embodiment which are similar to the luminous keyboard  3 K of the eleventh embodiment are not redundantly described herein. In comparison with the eleventh embodiment, the light amount control structures  351 L of the luminous keyboard  3 L of this embodiment further comprises plural light absorption structures  352 L corresponding to the plural light-emitting elements  32 L. 
     Please refer to  FIG. 16  again. The light absorption structures  352 L are disposed on the uneven surfaces of the corresponding light amount control structures  351 L (i.e., texturing structures). The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 L will be absorbed by the light absorption structures  352 L. Consequently, the reflected fraction of the plural light beams B is reduced. Moreover, the shapes of the light absorption structures  352 L match the shapes of the corresponding light amount control structures  351 L (i.e., texturing structures). That is, the light absorption structures  352 L also have uneven surfaces. The light absorption structures  352 L can absorb portions of the light beams B and increase the number of times of reflecting the light beams B. Consequently, the reflected fraction of the light beams B is further reduced. 
     The present invention further provides a luminous keyboard of a thirteenth embodiment, which is distinguished from the above embodiments.  FIG. 17  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a thirteenth embodiment of the present invention. As shown in  FIG. 17 , the luminous keyboard  3 M comprises a keypad module  30 M, a supporting plate  31 M, plural light-emitting elements  32 M, an illumination circuit board  33 M, a light guide plate  34 M, a first reflecting plate  35 M and a second reflecting plate  36 M. For clarification and brevity, only one light-emitting element  32 M is shown in the drawing. The keypad module  30 M comprises plural keycaps  301 M, plural connecting elements  302 M, plural elastic elements  303 M and a switch circuit member  304 M. Each keycap  301 M has a light-outputting zone  305 M. The light guide plate  34 M comprises plural light-guiding structures  341 M. Each light-guiding structure  341 M is aligned with the corresponding light-outputting zone  305 M. The second reflecting plate  36 M further comprises plural openings  361 M. Each opening  361 M is aligned with the corresponding light-outputting zone  305 M. The components of the luminous keyboard  3 M of this embodiment which are similar to the luminous keyboard  3 L of the twelfth embodiment are not redundantly described herein. In comparison with the ninth embodiment, the following two aspects of the luminous keyboard  3 M of this embodiment are distinguished. Firstly, the luminous keyboard  3 M of this embodiment is not equipped with the light-shading plate, and the second reflecting plate  36 M can replace the light-shading plate. Secondly, the second reflecting plate  36 M of the luminous keyboard  3 M comprises plural openings  361 M and plural second light amount control structures  362 M (only one is shown in the drawing). 
     As shown in  FIG. 17 , plural first light amount control structures  351 M are integrally formed with the first reflecting plate  35 M to be first texturing structures. The plural first light amount control structures  351 M are arranged between the first reflecting plate  35 M and the light guide plate  34 M, and disposed on a top surface of the first reflecting plate  35 M. That is, the first light amount control structures  351 M are located at specified regions near the corresponding light-emitting elements  32 M. Moreover, the first reflecting plate  35 M further comprises plural light absorption structures  352 M corresponding to the plural first light amount control structures  351 M. The first light amount control structures  351 M are disposed on the uneven surfaces of the first light amount control structures  351 M (i.e., the first texturing structures). The plural second light amount control structures  362 M are arranged between the second reflecting plate  36 M and the light guide plate  34 M. That is, the second light amount control structures  362 M are disposed on a bottom surface of the second reflecting plate  36 M, and located at specified regions near the corresponding light-emitting elements  32 M. Moreover, the second light amount control structures  362 M have respective second texturing structures  363 M. The first light amount control structures  351 M are not overlapped with the corresponding second light amount control structures  362 M. The propagating processes of the light beams B through the first light amount control structures  351 M and the light absorption structures  352 M and the propagating processes of the light beams B through the second light amount control structures  362 M and the second texturing structures  363 M are similar to those of the luminous keyboard  3 I of the ninth embodiment, and are not redundantly described herein. 
     The structure of the luminous keyboard  3 M of this embodiment may be modified. For example, in a variant example, only the first light amount control structures are disposed on the top surface of the first reflecting plate, or only the second light amount control structures are disposed on the bottom surface of the second reflecting plate. That is, only one reflecting plate has the light amount control structures. In another variant example, the plural light-emitting elements and the illumination circuit board are inverted. By changing the locations of some components, different stack structures of the luminous keyboard can be produced. These stack structures can diminish the problem of generating bright spots. 
     The present invention further provides a luminous keyboard of a fourteenth embodiment, which is distinguished from the above embodiments.  FIG. 18  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fourteenth embodiment of the present invention. As shown in  FIG. 18 , the luminous keyboard  3 N comprises a keypad module  30 N, a supporting plate  31 N, plural light-emitting elements  32 N, an illumination circuit board  33 N, a light guide plate  34 N, a light absorption plate  35 N and a light-shading plate  36 N. For clarification and brevity, only one light-emitting element  32 N is shown in the drawing. The keypad module  30 N comprises plural keycaps  301 N, plural connecting elements  302 N, plural elastic elements  303 N and a switch circuit member  304 N. Each keycap  301 N has a light-outputting zone  305 N. The light guide plate  34 N comprises plural light-guiding structures  341 N. Each light-guiding structure  341 N is aligned with the corresponding light-outputting zone  305 N. Moreover, the light absorption plate  35 N comprises plural light amount control structures  351 N corresponding to the plural light-emitting elements  32 N. For brevity, only one light amount control structure  351 N is shown in the drawing. The components of the luminous keyboard  3 N of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the luminous keyboard  3 N of this embodiment further comprises the light absorption plate  35 N in replace of the reflecting plate. 
     As shown in  FIG. 18 , the light absorption plate  35 N is disposed under the light guide plate  34 N. The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 N will be reflected by the light absorption plate  35 N. Consequently, the utilization efficiency of the portions of the plural light beams B that are not subjected to total internal reflection will be enhanced. Moreover, the light absorption plate  35 N comprises plural light amount control structures  351 N corresponding to the plural light-emitting elements  32 N. For brevity, only one light amount control structure  351 N is shown in the drawing. The light amount control structures  351 N are disposed on a top surface of the light absorption plate  35 N, and located near the corresponding light-emitting elements  32 N. That is, the plural light amount control structures  351 N are arranged between the light absorption plate  35 N and the light guide plate  34 N, and located at specified regions near the corresponding light-emitting elements  32 N. In this embodiment, the plural light amount control structures  351 N are made of anti-reflection materials and deposited on the top surface of the light absorption plate  35 N. Moreover, the light absorption plate  35 N is made of a light absorption material. 
     The illumination of the luminous keyboard  3 N will be illustrated as follows. When the plural light-emitting elements  32 N emit the plural light beams B, portions of the light beams B are laterally introduced into the light guide plate  34 N and subjected to total internal reflection within the light guide plate  34 N. The light beams B can be guided to the corresponding light-outputting zones  305 N by the light-guiding structures  341 N so as to illuminate the light-outputting zones  305 N. On the other hand, other portions of the plural light beams B are introduced into the light guide plate  34 N at a larger incident angle and unable to be subjected to total internal reflection within the light guide plate  34 N, and thus shaded by the light-shading plate  36 N and reflected to the light guide plate  34 N. The portions of the plural light beams B reflected by the second reflecting plate  36 N are transmitted through the light guide plate  34 N, and then transferred through the light amount control structures  351 N. 
     When the light beams B are transferred through the light amount control structures  351 N, portions of the light beams B are absorbed by the light amount control structures  351 N. The remaining small portions of the light beams B are transmitted through the light amount control structures  351 N and absorbed and reflected by the underlying light absorption plate  35 N, and no longer shaded by the light-shading plate  36 N. Consequently, the remaining small portions of the light beams B are projected to the keycaps  301 N and not directly projected to the light-outputting zones  305 N. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. Under this circumstance, the luminous uniformity is enhanced. 
     Although the light absorption plate  35 N is not a reflecting plate, the light absorption plate  35 N has reflecting capability to a certain extent. The reflecting capability of the light absorption plate  35 N is lower than the reflecting capability of the reflecting plate. That is, the light absorption plate  35 N can absorb portions of the light beams B, and the portions of the light beams B that are not absorbed will be reflected to the keycaps  301 N by the light absorption plate  35 N. 
     The present invention further provides a luminous keyboard of a fifteenth embodiment, which is distinguished from the above embodiments.  FIG. 19  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a fifteenth embodiment of the present invention. As shown in  FIG. 19 , the luminous keyboard  3 P comprises a keypad module  30 P, a supporting plate  31 P, plural light-emitting elements  32 P, an illumination circuit board  33 P, a light guide plate  34 P, a first light absorption plate  35 P and a second light absorption plate  36 P. For clarification and brevity, only one light-emitting element  32 P is shown in the drawing. The keypad module  30 P comprises plural keycaps  301 P, plural connecting elements  302 P, plural elastic elements  303 P and a switch circuit member  304 P. Each keycap  301 P has a light-outputting zone  305 P. The light guide plate  34 P comprises plural light-guiding structures  341 P. Each light-guiding structure  341 P is aligned with the corresponding light-outputting zone  305 P. Moreover, the second light absorption plate  36 P comprises plural openings  361 P. Each opening  361 P is aligned with the corresponding light-outputting zone  305 P. The components of the luminous keyboard  3 P of this embodiment which are similar to the luminous keyboard  3 N of the fourteenth embodiment are not redundantly described herein. In comparison with the fourteenth embodiment, the following two aspects of the luminous keyboard  3 P of this embodiment are distinguished. Firstly, the luminous keyboard  3 P of this embodiment is not equipped with the light-shading plate, and the second light absorption plate  36 P can replace the light-shading plate. Secondly, the second light absorption plate  36 P of the luminous keyboard  3 P comprises plural openings  361 P and plural second light amount control structures  362 P (only one is shown in the drawing). 
     The plural second light amount control structures  362 P are arranged between the second light absorption plate  36 P and the light guide plate  34 P. That is, the second light amount control structures  362 P are disposed on a bottom surface of the second light absorption plate  36 P, and located at specified regions near the corresponding light-emitting elements  32 P. Moreover, the second light amount control structures  362 P have respective second texturing structures  363 P. The first light amount control structures  351 P are not overlapped with the corresponding second light amount control structures  362 P. The propagating processes of the light beams B through the second light amount control structures  362 P and the second texturing structures  363 P are similar to those of the luminous keyboard  3 I of the ninth embodiment, and are not redundantly described herein. 
     The structure of the luminous keyboard  3 P of this embodiment may be modified. For example, in a variant example, only the first light amount control structures are disposed on the top surface of the first light absorption plate, or only the second light amount control structures are disposed on the bottom surface of the second light absorption plate. That is, only one light absorption plate has the light amount control structures. In another variant example, the plural light-emitting elements and the illumination circuit board are inverted. By changing the locations of some components, different stack structures of the luminous keyboard can be produced. These stack structures can diminish the problem of generating bright spots. 
     The present invention further provides a luminous keyboard of a sixteenth embodiment, which is distinguished from the above embodiments.  FIG. 20  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a sixteenth embodiment of the present invention. As shown in  FIG. 20 , the luminous keyboard  3 N comprises a keypad module  30 Q, a supporting plate  31 Q, plural light-emitting elements  32 Q, an illumination circuit board  33 Q, a light guide plate  34 Q, a light absorption plate  35 Q and a light-shading plate  36 Q. For clarification and brevity, only one light-emitting element  32 Q is shown in the drawing. The keypad module  30 Q comprises plural keycaps  301 Q, plural connecting elements  302 Q, plural elastic elements  303 Q and a switch circuit member  304 Q. Each keycap  301 Q has a light-outputting zone  305 Q. The light guide plate  34 Q comprises plural light-guiding structures  341 Q. Each light-guiding structure  341 Q is aligned with the corresponding light-outputting zone  305 Q. Moreover, the light absorption plate  35 Q comprises plural light amount control structures  351 Q corresponding to the plural light-emitting elements  32 Q. For brevity, only one light amount control structure  351 Q is shown in the drawing. The components of the luminous keyboard  3 Q of this embodiment which are similar to the luminous keyboard  3 A of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the light amount control structures  351 Q of the luminous keyboard  3 Q of this embodiment are texturing structures, which are integrally formed with the light absorption plate  35 Q. 
     Please refer to  FIG. 20  again. The light amount control structures  351 Q are arranged between the light absorption plate  35 Q and the light guide plate  34 Q, and disposed on a top surface of the light absorption plate  35 Q. That is, the light amount control structures  351 Q are located at specified regions near the corresponding light-emitting elements  32 Q. By the light amount control structures  351 Q, the number of times that the light beams B are reflected is increased, and the reflected fraction of the light beams B is reduced. In other words, the light amount control structures  351 Q are not additional light absorption materials or additional anti-reflection materials on the light absorption plate  35 Q. Instead, the light amount control structures  351 Q are texturing structures that are formed by machining the light absorption plate  35 Q. Although the structures of the luminous keyboard  3 Q of this embodiment are somewhat different from the structures of the luminous keyboards of the above embodiments, the luminous keyboard  3 Q also has enhanced luminous uniformity. The illumination of the luminous keyboard  3 Q is similar to the illumination of the luminous keyboards of the above embodiments, and is not redundantly described herein. 
     The present invention further provides a luminous keyboard of a seventeenth embodiment, which is distinguished from the above embodiments.  FIG. 21  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to a seventeenth embodiment of the present invention. As shown in  FIG. 21 , the luminous keyboard  3 R comprises a keypad module  30 R, a supporting plate  31 R, plural light-emitting elements  32 R, an illumination circuit board  33 R, a light guide plate  34 R, a light absorption plate  35 R and a light-shading plate  36 R. For clarification and brevity, only one light-emitting element  32 R is shown in the drawing. The keypad module  30 R comprises plural keycaps  301 R, plural connecting elements  302 R, plural elastic elements  303 R and a switch circuit member  304 R. Each keycap  301 R has a light-outputting zone  305 R. The light guide plate  34 R comprises plural light-guiding structures  341 R. Each light-guiding structure  341 R is aligned with the corresponding light-outputting zone  305 R. Moreover, the light absorption plate  35 R comprises plural first light amount control structures  351 R corresponding to the plural light-emitting elements  32 R. For brevity, only one first light amount control structure  351 R is shown in the drawing. The components of the luminous keyboard  3 R of this embodiment which are similar to the luminous keyboard  3 K of the eleventh embodiment are not redundantly described herein. In comparison with the eleventh embodiment, the light absorption plate  35 R of the luminous keyboard  3 R of this embodiment further comprises plural second light amount control structures  352 R corresponding to the first light amount control structures  351 R. 
     Please refer to  FIG. 21  again. The second light amount control structures  352 R are disposed on the uneven surfaces of the corresponding first light amount control structures  351 R (i.e., texturing structures). The portions of the plural light beams B that are not subjected to total internal reflection within the light guide plate  34 R will be absorbed by the second light amount control structures  352 R. Consequently, the reflected fraction of the plural light beams B is reduced. Moreover, the shapes of the second light amount control structures  352 R match the shapes of the corresponding first light amount control structures  351 R (i.e., texturing structures). That is, the second light amount control structures  352 R also have uneven surfaces. In an embodiment, the plural second light amount control structures  352 R are made of anti-reflection materials, and the plural second light amount control structures  352 R are deposited on a top surface of the light absorption plate  35 R. The second light amount control structures  352 R can absorb portions of the light beams B and increase the number of times of reflecting the light beams B. Consequently, the reflected fraction of the light beams B is further reduced. 
     The structure of the luminous keyboard  3 R of this embodiment may be modified. For example, in a variant example, the luminous keyboard further comprises a second light absorption plate over the light guide plate. Preferably, plural second first light amount control structures are disposed on the second light absorption plate. Alternatively, only the first light amount control structures are disposed on the top surface of the first light absorption plate, or only the second light amount control structures are disposed on the bottom surface of the second light absorption plate. That is, only one light absorption plate has the light amount control structures. In another variant example, the plural light-emitting elements and the illumination circuit board are inverted. By changing the locations of some components, different stack structures of the luminous keyboard can be produced. These stack structures can diminish the problem of generating bright spots. 
     The present invention further provides a luminous keyboard of an eighteenth embodiment, which is distinguished from the above embodiments.  FIG. 22  is a schematic cross-sectional view illustrating the structure of a luminous keyboard according to an eighteenth embodiment of the present invention. As shown in  FIG. 22 , the luminous keyboard  3 S comprises a keypad module  30 S, a supporting plate  31 S, plural light-emitting elements  32 S, an illumination circuit board  33 S, a light guide plate  34 S, a first reflecting plate  35 S and a second reflecting plate  36 S. For clarification and brevity, only one light-emitting element  32 S is shown in the drawing. The keypad module  30 S comprises plural keycaps  301 S, plural connecting elements  302 S, plural elastic elements  303 S and a switch circuit member  304 S. Each keycap  301 S has a light-outputting zone  305 S. The light guide plate  34 S comprises plural light-guiding structures  341 S. Each light-guiding structure  341 S is aligned with the corresponding light-outputting zone  305 S. The first reflecting plate  35 S comprises plural first light amount control structures  351 S (only one is shown in the drawing), and the second reflecting plate  36 S comprises plural second light amount control structures  362 S (only one is shown in the drawing). The components of the luminous keyboard  3 S of this embodiment which are similar to the luminous keyboard  3 E of the fifth embodiment are not redundantly described herein. In comparison with the fifth embodiment, the plural first light amount control structures  351 S and the plural second light amount control structures  362 S of the luminous keyboard  3 S are not overlapped. 
     From the above descriptions, the present invention provides a luminous keyboard. The luminous keyboard has a reflecting plate (or a light absorption plate) with a special structure. In particular, plural light amount control structures with many variant examples are disposed on the reflecting plate (or the light absorption plate), and the light amount control structures are arranged between a light guide plate and the reflecting plate (or the light absorption plate). That is, the light amount control structures are located at the reflecting path of the light beams. When the portions of the light beams that are not subjected to total internal reflection within the light guide plate are reflected by the reflecting plate (or the light absorption plate), the reflected fraction of the light beams is reduced by the light amount control structure. Since the light beams are not very centralized, the problem of generating bright spots will be diminished. For further reducing the reflected fraction of the light beams, the light amount control structures of the luminous keyboard may have different lengths according to the practical requirements. 
     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.