Patent Publication Number: US-2010108481-A1

Title: Light-emitting keyboard with a membrane circuit board incorporated therein

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light-emitting keyboard, and more particularly, to a light-emitting keyboard that facilitates reducing the manufacturing costs and overall thickness. 
     2. Description of the Related Art 
     With the popularity of computer, users not only pursue better computer efficiency but also pay more attention to the function and design of computer accessories such as mouse and keyboard. As computer has become an indispensable device in nearly every aspect of modern life from telecommunication, commerce, editing to graphics design, some manufacturers equip keyboard, one of the most important input devices for computer, with backlit keys so that the user can perform input tasks under inadequate lighting. Besides, the back lighting makes the keyboard look fancy. 
     A conventional light-emitting keyboard typically includes a light guide. For example, the light-emitting keyboard disclosed in ROC Publication No. 509955 comprises: a keyboard portion; and a backlit device having a light guide, a reflector and a light source; wherein the light travels in the light guide and then is reflected to enter the keyboard portion by the reflector. In addition, the bottom surface of the light guide is provided with a plurality of light reflecting portions corresponding to the transparent spacer layer such that the light originated from the light source and entering the light guide is refracted when reaching the light reflecting portions, and then said light is reflected to the keyboard portion to reinforce the luminescent efficiency of the key. The light reflecting portions may be formed by printing a plurality of reflecting dots onto the bottom surface of the light guide, or they may be formed integrally with the bottom surface of the light guide creating a rough reflecting surface. 
     The light guide is an indispensable component for a light-emitting keyboard in the aforementioned prior techniques. However, as the light guide is of a certain thickness, the overall thickness of the light-emitting keyboard incorporating said light guide increases correspondingly. Moreover, the inclusion of a light guide also increases the overall manufacturing costs of a light-emitting keyboard. 
     Accordingly, how to effectively reduce the overall thickness as well as the manufacturing costs of a light-emitting keyboard is an important issue for the manufacturers. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a light-emitting keyboard and a membrane circuit board incorporated therewithin that facilitate reducing the manufacturing costs. 
     Another object of the present invention is to provide a light-emitting keyboard and a membrane circuit board incorporated therewithin that facilitate increasing the luminescent efficiency. 
     Yet another object of the present invention is to provide a light-emitting keyboard and a membrane circuit board incorporated therewithin that facilitate reducing the overall thickness of the keyboard. 
     A light-emitting keyboard that achieves the aforementioned objects comprises: a membrane circuit board whose bottom surface is printed with a light guide ink; a light source provided on one side of the membrane circuit board for projecting light to enter the light guide ink of the membrane circuit board; a first reflector disposed underneath the membrane circuit board to reflect a portion of the light that escapes from the membrane circuit board to enter the light guide ink of the membrane circuit board; a second reflector disposed on top of the membrane circuit board to reflect a portion of the light that does not pass therethrough back towards the light guide ink, the second reflector being provided with a first opening; a supporting plate disposed on top of the second reflector, the supporting plate being provided with a second opening corresponding to the first opening of the second reflector and a plurality of first and second fixation brackets adjacent to the second opening; a scissor assembly disposed on top of the supporting plate, the scissor assembly being provided with a top hinge portion, a bottom hinge portion engaged with the plurality of first and second fixation brackets of the supporting plate and a third opening corresponding to the first and second openings; a keycap disposed on top of the scissor assembly, the keycap being provided with a top retaining portion engaged with the top hinge portion of the scissor assembly; and an elastic contact body having a contact portion, the elastic contact body being configured to pass through the first, second and third openings so as to be disposed between the keycap and the membrane circuit board. 
     The abovementioned membrane circuit board includes an upper plate, a spacer plate and a lower plate, and the light guide ink is rolled over the bottom surface of the lower plate. 
     The abovementioned light guide ink is distributed evenly over the bottom surface of the lower plate. 
     The abovementioned light guide ink is distributed unevenly over the bottom surface of the lower plate. 
     The light guide ink is printed over the bottom surface of the lower plate in the form of matrix. 
     The size of the light guide ink printed over the bottom surface of the lower plate varies depending on the size of each keycap. 
     The closer the distance between the light guide ink and the light source, the lower the density of the light guide ink; the farther the distance between the light guide ink and the light source, the greater the density of the light guide ink. 
     The light-emitting keyboard of the present invention further comprises a reinforcement board disposed between the membrane circuit board and the second reflector, the reinforcement board being provided with a plurality of fasteners. 
     A plurality of fastener apertures are configured on the membrane circuit board, the second reflector and the supporting plate respectively, allowing the plurality of fasteners of the reinforcement board to pass therethrough such that the reinforcement board, the membrane circuit, the second reflector and the supporting plate may be secured in a stack. 
     The light source is controlled by a base circuit board and provided adjacent to a lateral side of the membrane circuit board. 
     A membrane circuit board that achieves the abovementioned objects is incorporated in a keyboard. The membrane circuit board comprises: an upper plate; a spacer plate; and a lower plate whose bottom surface is printed with a light guide ink that receives the light originated from a light source and then radiates the light upward to illuminate the keyboard. 
     By having the bottom surface of the membrane circuit board incorporated in the light-emitting keyboard of the present invention printed with the light guide ink, the keyboard does not need to include an additional light guide. Consequently, the manufacturing costs and overall thickness of the keyboard can be reduced, and the luminescent efficiency can be increased as well. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view showing a light-emitting keyboard of the present invention. 
         FIG. 2  is a sectional view showing a light-emitting keyboard of the present invention. 
         FIG. 3  is an exploded view showing a membrane circuit board incorporated in the light-emitting keyboard of the present invention. 
         FIG. 4  is a bottom view showing a membrane circuit board incorporated in the light-emitting keyboard of the present invention. 
         FIG. 5  is a bottom view showing another embodiment of a membrane circuit board incorporated in the light-emitting keyboard of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
       FIGS. 1 and 2  show an exploded view and a sectional view of the first embodiment of a light-emitting keyboard of the present invention, respectively. For illustration purposes, a person skilled in the art shall understand that a single key unit of the light-emitting keyboard illustrated in the drawings represents a group of similar key units on the keyboard. Modules similar to those equipped in a keyboard, such as top casing and bottom casing, are omitted for illustration purposes. 
     A light-emitting keyboard  100  of the present invention comprises: a membrane circuit board  10  whose bottom surface is printed with a light guide ink  11  (see  FIGS. 4 and 5 ); a light source  20  disposed on one side of the membrane circuit board  10  for projecting light to enter the light guide ink  11  of the membrane circuit board  10 ; a first reflector  30  disposed underneath the membrane circuit board  10  to reflect a portion of the light that escapes from the membrane circuit board  10  to enter the light guide ink  11  of the membrane circuit board  10 ; a second reflector  40  provided on top of the membrane circuit board  10  to reflect a portion of the light that does pass therethrough back towards the light guide ink  11 ; a supporting plate  50  disposed on top of the second reflector  40 , a scissor assembly  60  disposed on top of the supporting plate  50 ; a keycap  70  disposed on top of the scissor assembly  60 ; and an elastic contact body  80  having a contact portion. 
     Referring to  FIGS. 1 and 2 , the light source  20  is controlled and powered by a base circuit board (not shown) and disposed adjacent to a lateral side of the membrane circuit board  10 ; the second reflector  40  is provided with a first opening  41 ; the supporting plate  50  is provided with a second opening  51  opposed to the first opening  41  of the second reflector  40  and a plurality of first and second fixation brackets  52  and  53  adjacent to the second opening  51 ; the scissor assembly  60  is provided with a top hinge portion  61 , a bottom hinge portion  62  and a third opening  63  corresponding to the first and second openings  41  and  51 ; the keycap  70  is provided with a top retaining portion  71 ; wherein the bottom hinge portion  62  of the scissor assembly  60  is engaged with the plurality of first and second fixation brackets  52  and  53  of the supporting plate  50  respectively and the top hinge portion  61  of the scissor assembly  60  is coupled to the top retaining portion  71  of the keycap  70  such that the keycap  70 , the scissor assembly  60  and the supporting plate  50  are engaged together; and wherein the elastic contact body  80  passes through the first opening  41 , the second opening  51  and the third opening  63  so as to be disposed between the keycap  70  and the membrane circuit board  10 . 
     The light-emitting keyboard  100  of the present invention further comprises a reinforcement board  90  disposed between the membrane circuit board  10  and the second reflector  40 , the reinforcement board  90  being provided with a plurality of fasteners  91 . Moreover, a plurality of fastener apertures  15  corresponding to the plurality of fasteners  91  of the reinforcement board  90  are configured on the membrane circuit board  10 , the second reflector  40  and the supporting plate  50  respectively, allowing the plurality of fasteners  91  to pass therethrough such that the reinforcement board  90 , the membrane circuit board  10 , the second reflector  40  and the supporting plate  50  can be secured in a stack. Therefore, the reinforcement board  90  can stabilize and reinforce the structures and components disposed thereon, including the membrane circuit board  10 , the second reflector  40 , the supporting plate  50 , the scissor assembly  60  and the keycap  70 . 
       FIGS. 3 and 4  show an exploded view and a bottom view of a membrane circuit board incorporated in the light-emitting keyboard of the present invention, respectively. The membrane circuit board  10  comprises an upper plate  12 , a spacer plate  13  and a lower plate  14 , and the light guide ink  11  is rolled over the bottom surface of the lower plate  14 . As shown in  FIG. 4 , the light guide ink  11  is distributed evenly over the bottom surface of the lower plate  14 ; wherein the closer the distance between the light guide ink  11  and the light source  20 , the lower the density of the light guide ink  11 ; and wherein the farther the distance between the light guide ink  11  and the light source  20 , the greater the density of the light guide ink. 
     In this embodiment, the light guide ink  11  is printed over the bottom surface of the lower plate  14  in the form of matrix. Alternatively, the light guide ink  11  may be printed over the bottom surface of the lower plate  14  in the form of reticulation or in any other forms. 
       FIG. 5  is a bottom view showing another embodiment of a membrane circuit board incorporated in the light-emitting keyboard of the present invention. The only difference between this embodiment and the embodiment of  FIG. 4  is that, in this embodiment, the light guide ink  11  is printed under each keycap  70  correspondingly, and the size of the light guide ink  11  printed over the bottom surface of the lower plate  14  varies depending on the size of each keycap  70 . Consequently, the light guide ink  11  is distributed unevenly over the bottom surface of the lower plate  14 . 
     The bottom surface of the membrane circuit board  10  incorporated in the light-emitting keyboard  100  of the present invention is printed with the light guide ink  11  to receive the light originated from the light source  20  and then direct the light in a vertical upward direction; wherein a portion of the light sequentially passes through the membrane circuit board  10 , the second reflector  40 , the supporting plate  50  and the scissor assembly  60 , and then reaches the keycap  70  to illuminate the keycap  70 ; meanwhile, the second reflector  40  reflects another portion of the light that does not pass therethrough back towards the light guide ink  11  of the membrane circuit board  10  such that the portion of the light can again be radiated towards the keycap  70  to illuminate the keycap  70  and further reinforce the luminescent efficiency of the light-emitting keyboard. 
     In addition, when the light originated from the light source  20  is radiated in a vertical upward direction via the light guide ink  11 , a potion of the light may dissipate downwardly and then be reflected upward by the first reflector  30  to pass through the components and structures configured between the first reflector  30  and the keycap  70 , including the membrane circuit board  10 , the second reflector  40 , the supporting plate  50  and the scissor assembly  60 , thereby to illuminate the keycap  70  and further reinforce the luminescent efficiency of the light-emitting keyboard  100 . 
     By having the bottom surface of the membrane circuit board incorporated in the light-emitting keyboard of the present invention printed with the light guide ink, the keyboard does not need to include an additional light guide. Consequently, the manufacturing costs and overall thickness of the keyboard can be reduced, and the luminescent efficiency can be increased as well. 
     While this invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that this invention is not limited hereto, and that various changes and modifications can be made herein without departing from the spirit and scope of this invention as defined by the appended claims. In addition, the scope of the present invention is not limited to the applications listed in the specification. For example, the light guide ink may be printed over the bottom surface of the lower plate of the membrane circuit board by rolling, laser beams, etching or any applicable methods.