Patent Publication Number: US-9887052-B1

Title: Light guide plate and light emitting keyboard having the same

Description:
FIELD 
     The disclosure relates to a keyboard, and more particularly to a light emitting keyboard and a light guide plate thereof. 
     BACKGROUND 
       FIG. 1  illustrates a light guide plate  9  of a light emitting keyboard, as disclosed by the applicant in Taiwanese Patent No. M525536. The light guide plate  9  is composed of a plurality of light guide blocks  91 , each of which has a plurality of spaced-apart light blocking spaces  912  dividing the light guide block  91  into a plurality of light guide portions  911 , and a plurality of light source receiving spaces  913  corresponding to the light guide portions  911  and respectively receiving the light sources (not shown). The light guide portions  911  correspond to the keys (not shown) of the light emitting keyboard. The light blocking spaces  912  are used to restrict light emitted from each light source to transmit within a respective one of the light guide portions  911 . Through this, the luminance of each light guide portion  911  is controlled by a single light source, and is not affected by the other light sources. Hence, the luminance of the light guide portions  911  is uniform and approaches the luminance of each light source, and the luminance of light transmissive portions of the keys is also uniform. 
     However, since the light blocking spaces  912  can only prevent light emitted from each light source to transmit to a neighboring light guide portion  911 , light emitted from the light sources in each light guide block  91  can still leak through a peripheral side thereof, so that the brightness of light emitted by each light guide portion  911  to the corresponding key is weakened, thereby reducing the light utilization efficiency of each light source. Further, although an outer frame (not shown) can be used to interconnect six rows of the light guide blocks  91  of the light guide plate  9 , clearances among the light guide blocks  91  still exist. Moreover, each light guide block  91  has the light blocking spaces  912 , so that the structural strength of the entire light guide plate  9  is weak, that is, each light guide block  91  is easily bent by an external force that causes the entire light guide plate  9  to warp, thereby adversely affecting the degree of closeness of the light guide plate  9  with the other components of the light emitting keyboard during assembly. Hence, there is still room for improvement of the light guide plate  9 . 
     SUMMARY 
     Therefore, an object of the present disclosure is to provide a light emitting keyboard and a light guide plate thereof that can alleviate at least one of the drawbacks of the prior art. 
     According to one aspect of this disclosure, a light guide plate is configured to be disposed on a bottom side of a keyboard module having a plurality of keys, and comprises a light shielding plate body, a light guide plate body and a plurality of light source receiving spaces. The light shielding plate body includes a peripheral frame, a plurality of longitudinal and transverse partition strips provided in the peripheral frame, and a plurality of light guide regions cooperatively defined by the peripheral frame and the longitudinal and transverse partition strips. The light guide regions are configured to respectively align with the keys. The light guide plate body includes a plurality of light guide blocks embedded in the light guide regions, respectively. The light source receiving spaces correspond to the light guide blocks. 
     According to another aspect of this disclosure, a light emitting keyboard includes a keyboard module and a backlight module. The keyboard module includes a base plate, and a plurality of keys disposed on a top surface of the base plate and movable upward and downward relative to the base plate. The base plate has a plurality of through holes corresponding to the keys. The keys are located respectively above the through holes. Each key has at least one light transmissive portion facing a corresponding one of the through holes. The backlight module is disposed on a bottom surface of the base plate and includes a light guide plate and a light emitting unit. The light guide plate has a light shielding plate body, a light guide plate body and a plurality of light source receiving spaces. The light shielding plate body includes a peripheral frame, a plurality of longitudinal and transverse partition strips provided in the peripheral frame, and a plurality of light guide regions cooperatively defined by the peripheral frame and the longitudinal and transverse partition strips. The light guide regions are configured to respectively align with the keys. The light guide plate body includes a plurality of light guide blocks embedded in the light guide regions, respectively. The light source receiving spaces correspond to the light guide blocks. The light emitting unit includes a plurality of light sources respectively received in the light source receiving spaces. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a top view of a light guide plate of a light emitting keyboard disclosed in Taiwanese Patent No. M525536; 
         FIG. 2  is a top view of a light emitting keyboard according to an embodiment of the present disclosure; 
         FIG. 3  is a fragmentary exploded top view of the embodiment; 
         FIG. 4  is a fragmentary top view of the embodiment in an assembled state; 
         FIG. 5  is an enlarged fragmentary sectional view of the embodiment in the assembled state; 
         FIG. 6  is a top view of a light guide plate of the embodiment; and 
         FIG. 7  is a fragmentary sectional view, illustrating a connecting relationship between a light shielding plate body and a light guide plate body of the light guide plate of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 2 to 5 , a light emitting keyboard according to the embodiment of the present disclosure is shown to include a keyboard module  100  and a backlight module  200 . 
     The keyboard module  100  includes a base plate  1 , a plurality of keys  2  and a transparent circuit film  3 . The base plate  1  has opposite top and bottom surfaces  11 ,  12 , and a plurality of spaced-apart through holes  13  extending through the top and bottom surfaces  11 ,  12 . 
     The keys  2  are disposed on the top surface  11  of the base plate  1  and are located respectively above the through holes  13 . Each key  2  has at least one light transmissive portion  21  facing a corresponding one of the through holes  13 . The light transmissive portion  21  of each key  2  is a character/symbol to be displayed by each key  2 . The transparent circuit film  3  is disposed on the top surface  11  of the base plate  1  below the keys  2 . In this embodiment, each key  2  is movable upward and downward relative to the base plate  1  through a scissors-type support mechanism  22  and a resilient member  23 , and contacts the transparent circuit film  3  through the resilient member  23  to generate a trigger signal. Since the assembly and structure of the components of the keyboard module  100  are well known in the art, a detailed description thereof is dispensed herewith for the sake of brevity. Further, the assembly and structure of the components of the keyboard module  100  are also not limited to the aforesaid disclosure. 
     The backlight module  200  is disposed on the bottom surface  12  of the base plate  1 , covers the through holes  13 , and is located below the keys  2  for projecting light to the keys  2 . The backlight module  200  includes a light shielding plate  4 , a light guide plate  5 , a light reflecting member  6  and a light emitting unit  7 . 
     The light shielding plate  4  is disposed on the bottom surface  12  of the base plate  1 , and includes a top surface  41  facing the bottom surface  12  of the base plate  1 , a bottom surface  42  opposite to the top surface  41 , and a plurality of light transmissive regions  43  respectively corresponding to the through holes  13 . 
     With reference to  FIGS. 4 to 6 , the light guide plate  5  is disposed on the bottom surface  42  of the light shielding plate  4 , and has a top surface  51  facing the bottom surface  42  of the light shielding plate  4 , and a bottom surface  52  opposite to the top surface  51 . The light guide plate  5  includes a light shielding plate body  53 , a light guide plate body  54 , and a plurality of light source receiving spaces  55 . 
     The light shielding plate body  53  has the top and bottom surfaces  51 ,  52  of the light guide plate  5 , and is made of non-light-transmissive material, such as a black acrylo-nitrile-butadiene-styrene (ABS) polymer. The light shielding plate body  53  includes a peripheral frame  530  and a plurality of longitudinal and transverse partition strips  531 ,  532 . 
     The peripheral frame  530  includes opposite left and right walls  534 ,  535 , a rear wall  536  having two opposite ends respectively connected to rear ends of the left and right walls  534 ,  535 , and a front wall  537  having two opposite ends respectively connected to front ends of the left and right walls  534 ,  535 . Each longitudinal partition strip  531  has two opposite ends respectively connected to the left and right walls  534 ,  535 . The longitudinal partition strips  531  divide the peripheral frame  530  into a plurality of rows of light guide spaces  533 . 
     The transverse partition strips  532  includes a plurality of first transverse partition strips ( 532   a ) connected to the rear wall  536 , a plurality of second transverse partition strips ( 532   b ) connected to the front wall  537 , and a plurality of third transverse partition strips ( 532   c ) connected to a corresponding one of the longitudinal partition strips  531 . Each of the first to third transverse partition strips ( 532   a ,  532   b ,  532   c ) has a connecting end  538  connected to a corresponding one of the rear wall  536 , the front wall  537  and the longitudinal partition strips  531 , and a free end  539  opposite to the connecting end  538 . 
     Each row of the light guide spaces  533  has a corresponding one of the first to third transverse partition strips ( 532   a ,  532   b ,  532   c ) therein, and is partitioned by the same into a plurality of light guide regions  5331  that respectively align with the keys  2 . 
     In this embodiment, the front wall  537  has a substantially “Z” shape, and includes a first longitudinal portion  5371 , a second longitudinal portion  5372  and an intermediate transverse portion  5373  interconnecting the first and second longitudinal portions  5371 ,  5372 . A frontmost one of the longitudinal partition strips  531  has two opposite ends respectively connected to the right wall  535  of the peripheral frame  530  and a junction between the first longitudinal portion  5371  and the intermediate transverse portion  5373 . The connection relationship of the longitudinal partition strips  531  with the peripheral frame  530  may be altered according to the configuration of the keys  2 , and is not limited to what is disclosed herein. 
     The light guide plate body  54  is made of a light transmissive material, such as polycarbonate (PC), and includes a plurality of light guide blocks  541  respectively embedded in the light guide regions  5331 , and a plurality of connecting portions  542  each of which is connected between two adjacent ones of the light guide blocks  541 . Each connecting portion  542  is embedded between two adjacent ones of the light guide regions  5331  and is located immediately adjacent the free end  539  of the corresponding one of the first to third transverse partition strips ( 532   a ,  532   b ,  532   c ). The thickness of the light guide plate body  54  is not greater than that of the light shielding plate body  53 . The light guide plate body  54  and the light shielding plate body  53  can be made through a bi-injection molding process or an embedded injection molding process. In this embodiment, the light guide plate body  54  and the light shielding plate body  53  have the same thickness, and have flush top surfaces and flush bottom surfaces. However, it is not limited thereto. When the thickness of the light guide plate body  54  is smaller than that of the light shielding plate body  53 , the top or bottom surface of the light guide plate body  54  is indented and located in the corresponding light guide region  5331 . 
     The light source receiving spaces  55  respectively correspond to the light guide blocks  541 . In this embodiment, the light source receiving spaces  55  are formed in the longitudinal partition strips  531  and respectively face the light guide blocks  541 . Each light source receiving space  55  is proximate to a free end  539  of a corresponding one of the first to third transverse partition strips ( 532   a ,  532   b ,  532   c ). However, it is not limited thereto. The light source receiving spaces  55  may also be formed in the respective light guide blocks  541 . 
     It is worth to mention herein that the free end  539  of each of the first and third transverse partition strips ( 532   a ,  532   b ) may be connected to an adjacent one of the longitudinal partition strips  531 , and the free end  539  of each second transverse partition strip ( 532   b ) may be connected to a frontmost longitudinal partition strip  531 . Further, the first transverse partition strips ( 532   a ) may extend from a rearmost longitudinal partition strip  531  toward the rear wall  536 , and the free ends  539  thereof may be connected to the rear wall  536 . Moreover, the light guide plate body  54  may only have the light guide blocks  541  respectively embedded in the light guide regions  5331 , and the light source receiving spaces  55  may be provided at any portion of the peripheral frame  530 , as long as they may correspond to the light guide blocks  541 . 
     Additionally, in order to increase the embedding strength between the light shielding plate body  53  and the light guide plate body  54  so as not to be easily separated from each other, engaging surfaces of the light shielding plate body  53  and the light guide plate body  54  are non-smooth surfaces having a groove and protrusion structure, or are inclined relative to each other, or are rough inclined surfaces (see  FIG. 7 ). 
     The light reflecting member  6  is disposed on and covers the bottom surface  52  of the light guide plate  5 , and has a plurality of light source through holes  61  corresponding to the light source receiving spaces  55 . In this embodiment, the light reflecting member  6  is a light reflecting plate. However, it is not limited thereto. The light reflecting member  6  may be a light reflecting film adhered to the bottom surface  52  of the light guide plate  5 . 
     The light emitting unit  7  includes a circuit board  71  disposed on a bottom side of the light reflecting member  6 , and a plurality of light sources  72  disposed on the circuit board  71 . The light sources  72  respectively extend through the light source through holes  61  and respectively receive in the light source receiving spaces  55 . Light emitted by each light source  72  is restricted to transmit within each light guide block  541  by the light shielding plate body  53 . In this embodiment, each light source  72  is a side emitting light-emitting diode (LED), and has a light emitting angle of less than 180 degrees. 
     When the light emitting angle of each light source  72  is determined, the extending configuration of the transverse partition strips  532  and the disposition thereof relative to each light source  72  are obtained by calculation. Thus, light emitted by each light source  72  of this embodiment can be restricted to transmit within each light guide block  541  and will not be transmitted outward through the connecting portion  542  between two adjacent ones of the light guide blocks  541 . 
     From the aforesaid description, it is apparent that through the structural design of the light shielding plate body  53  and the light guide plate body  54  of the light guide plate  5 , that is, the light shielding plate body  53  surrounds the light guide blocks  541  of the light guide plate body  54  so that light emitted by each light source  72  can be restricted to transmit within each light guide block  541  and can only be emitted outward through top and bottom surfaces of each light guide block  541 . Furthermore, through the cooperation of a light guide block  541  with a light source  72 , the luminance of each light guide block  541  is controlled by a single light source  72  and is not affected by the other light sources  72 . As such, the luminance of the light guide blocks  541  is uniform and approaches the luminance of each light source  72 , so that the luminance of the light transmissive portions  21  of the keys  2  is also uniform. Hence, when the light emitting keyboard of this disclosure is used in a dark place, a user can easily recognize the character/symbol on each key  2 . 
     Moreover, with the peripheral frame  530  of the light shielding plate body  53  surrounding a periphery of the light guide plate body  54 , the light guide plate  5  of this disclosure can resolve the existing problem of leakage of light emitted by the light source through a peripheral side of the light guide plate of the conventional light emitting keyboard, so that the light utilization efficiency of each light source  72  can be increased. Through the embedding engagement of the light guide plate body  54  with the light shielding plate body  53 , the structural strength of the entire light guide plate  5  can be effectively enhanced, so that assembly among the components of the light emitting keyboard of this disclosure can be facilitated. 
     In addition, because the light guide plate  5  can restrict the light emitted by each light source  72  to transmit outward only through the top and bottom surfaces of each light guide block  541 , the light shielding plate  4  disposed between the keyboard module  100  and the light guide plate  5  and the light reflecting member  6  disposed between the circuit board  71  and the light guide plate  5  may both be dispensed herewith. In this case, the non-light-transmissive circuit board  71  is adhered tightly to the bottom surface  52  of the light guide plate  5 , and a peripheral edge of the circuit board  71  is adhered to the peripheral frame  530  of the light guide plate  5 , so that the circuit board  71  may achieve the light reflecting effect substantially similar to that of the light reflecting member  6 . Through this, the light guide plate  5  can effectively reduce the thickness of the entire backlight module  200 . Therefore, the object of this disclosure can be achieved. 
     While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.