Patent Publication Number: US-2023143245-A1

Title: Luminous keyboard and optical module thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a luminous keyboard. Particularly, the invention relates to an optical module of a luminous keyboard. 
     2. Description of the Prior Art 
     With the rapid development of today&#39;s electronic technology and information industry, all kinds of electronic devices are developing towards the trend of light, thin, short, small, and diversified functions. For example, desktop and laptop computers have become indispensable electronic devices for modern people in daily life or work, and most of the peripheral products used are keyboards, which are the most common and very important input devices. As the electronic products become miniature and light-weighted, the slim border design is one of the important research and development approaches of keyboards today. However, for luminous keyboards, the integration of the keyswitch module and the backlight module must be considered, especially the adhesion between the multiple optical films of the backlight module and the avoidance of lateral light leakage, so that the lighting uniformity between the outer keyswitch and the inner keyswitch is not easy to control. In particular, in the slim border design, as the margin of the border is reduced, the luminous keyboard generally encounters the problem of too bright or too dark at the outer keyswitches. 
     Moreover, for the purpose of heat dissipation or positioning, the backlight module generally has a plurality of holes or openings to allow air or positioning means (e.g. bolts or screws) to pass therethrough, so that the keyswitches around the holes will become darker or brighter than other keyswitches. In addition, the keyswitches neighboring the light source of the backlight module will also become too bright or too dark in comparison with other keyswitches. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a luminous keyboard and an optical module thereof, which compensate for the brightness of the keyswitches by edge-lighting of the light guide sheet. 
     It is another object of the invention to provide a luminous keyboard and an optical module thereof, which incorporate the edge of the light guide sheet with the mask pattern design of the mask film and the patterned layer to enhance the lighting effect of keyswitches. 
     In an embodiment, the invention provides an optical module for a luminous keyboard including a plurality of keyswitches. The optical module includes a mask film having a mask pattern, a patterned layer disposed on the mask film, and a light guide sheet on one side of the mask film. The mask pattern defines a plurality of light-transparent regions respectively corresponding to the plurality of keyswitches, and an outer light-transparent region of the plurality of light-transparent regions has a region boundary. The patterned layer has a light transmittance larger than a light transmittance of the mask pattern. The light guide sheet has a light-exit edge, wherein a vertical projection of the light-exit edge of the light guide sheet on the mask film at least partially falls within the outer light-transparent region, and the patterned layer is at least partially located in the outer light-transparent region adjacent to the region boundary. 
     In an embodiment, the patterned layer extends from the region boundary into the outer light-transparent region to define a layer boundary, and the vertical projection of the light-exit edge of the light guide sheet on the mask film is located between the region boundary and the layer boundary. 
     In an embodiment, the patterned layer extends from the region boundary into the outer light-transparent region to define a layer boundary, and the vertical projection of the light-exit edge of the light guide sheet on the mask film is farther away from the region boundary than the layer boundary is. 
     In an embodiment, the light guide sheet has a hole, and a vertical projection of the hole on the mask film falls in the outer light-transparent region. 
     In an embodiment, the mask film further has an auxiliary mask pattern in the outer light-transparent region. The vertical projection of the hole at least partially overlaps the auxiliary mask pattern. The auxiliary mask pattern has a light transmittance larger than or equal to the light transmittance of the mask pattern. 
     In another embodiment, the invention provides an optical module for a luminous keyboard including a plurality of keyswitches. The optical module includes a mask film having a mask pattern, a patterned layer disposed on the mask film, and a light guide sheet on one side of the mask film. The mask pattern defines a plurality of light-transparent regions respectively corresponding to the plurality of keyswitches. The plurality of light-transparent regions includes an outer light-transparent region. The patterned layer has a light transmittance larger than a light transmittance of the mask pattern, wherein at least a portion of the patterned layer does not overlap the mask pattern and is adjacent to the outer light-transparent region, so as to define a region boundary of the outer light-transparent region together with the mask pattern. 
     In an embodiment, the light guide sheet has a light-exit edge, and a vertical projection of the light-exit edge on the mask film is located outside the outer light-transparent region and overlaps the at least a portion of the patterned layer. 
     In an embodiment, the optical module further includes a reflective film on one side of the light guide sheet opposite to the mask film, wherein a mask portion is disposed between the reflective film and the light guide sheet and adjacent to the light-exit edge, and a vertical projection of the mask portion on the mask film at least partially overlaps the at least a portion of the patterned layer. 
     In a further embodiment, the invention provides a luminous keyboard including a keyswitch module and the optical module described above. The keyswitch module includes a baseplate and a plurality of keyswitches disposed on the baseplate. The plurality of keyswitches includes at least one outer keyswitch and at least one inner keyswitch. The outer keyswitch includes a keycap, and an outer edge of the keycap is substantially aligned with an edge of the baseplate. The inner keyswitch is disposed at one side of the outer keyswitch away from the edge of the baseplate. The optical module is disposed under the baseplate, so that the mask film is closer to the baseplate than the light guide sheet is. The edge of the mask film adjacent to the region boundary is substantially aligned with the edge of the baseplate. 
     In an embodiment, a vertical projection of the keycap of the outer keyswitch on the mask film exceeds outside the region boundary of the outer light-transparent region. 
     In yet another embodiment, the invention provides an optical module for a luminous keyboard. The optical module includes a mask film having a mask pattern and a patterned layer disposed on the mask film. The mask pattern defines a light-transparent region, a light-shielding region, and a light modulation region. The light modulation region extends from the light-shielding region to the light-transparent region. The patterned layer has a light transmittance larger than a light transmittance of the mask pattern, wherein the patterned layer is located in the light modulation region, so the light modulation region has a light transmittance larger than a light transmittance of the light-shielding region and smaller than a light transmittance of the light-transparent region. 
     In an embodiment, the light modulation region includes a plurality of light-transparent sub-regions and a plurality of light-shielding sub-regions alternatingly disposed. At least a portion of the patterned layer is located in the light-transparent sub-regions. 
     In an embodiment, each of the plurality of light-shielding sub-regions has a gradually reduced width, so a width of each of the plurality of light-transparent sub-regions and a width of the portion of the patterned layer in each of the light-transparent sub-regions are gradually increased from the light-shielding region toward the light-transparent region. 
     In an embodiment, each of the plurality of light-shielding sub-regions has a substantially constant width, so a width of each of the plurality of light-transparent sub-regions and a width of the portion of the patterned layer in each of the light-transparent sub-regions are substantially constant from the light-shielding region to the light-transparent region. 
     In an embodiment, the optical module further includes a light source having a light-emitting surface, wherein a vertical projection of the light source on the mask film falls within the light-shielding region. The plurality of light-shielding sub-regions extends from the light-shielding region and is located between the light-transparent region and the light-emitting surface. 
     In an embodiment, the optical module further includes a light guide sheet having an edge. When the mask film is stacked on the light guide sheet, a vertical projection of the edge of the light guide sheet on the mask film at least partially falls in the light modulation region or in the light-shielding region adjacent to the light modulation region. 
     In an embodiment, the optical module further includes a light guide sheet having a hole. When the mask film is stacked on the light guide sheet, a vertical projection of an edge of the hole of the light guide sheet on the mask film at least partially falls within the light modulation region. 
     In an embodiment, the light modulation region includes a plurality of light-transparent sub-regions and a plurality of light-shielding sub-regions alternatingly disposed along the edge of the hole of the light guide sheet. At least a portion of the patterned layer is located in the light-transparent sub-regions, wherein each of the plurality of light-shielding sub-regions has a gradually reduced width, so a width of each of the plurality of light-transparent sub-regions and a width of the portion of the patterned layer in each of the light-transparent sub-regions are gradually increased from the light-shielding region toward the light-transparent region. 
     In an embodiment, the light modulation region includes a plurality of light-transparent sub-regions and a plurality of light-shielding sub-regions alternatingly disposed along the edge of the hole of the light guide sheet. At least a portion of the patterned layer is located in the light-transparent sub-regions, wherein each of the plurality of light-shielding sub-regions has a gradually increased width, so a width of each of the plurality of light-transparent sub-regions and a width of the portion of the patterned layer in each of the light-transparent sub-regions are gradually increased from the light-shielding region toward the light-transparent region. 
     In an embodiment, the light-shielding region partially surrounds the light-transparent region to form a boundary line, and two ends of the boundary line are substantially connected to middle sections of two opposite sides of the light modulation region. 
     In another embodiment, the invention provides a luminous keyboard including the optical module described above and at least one keyswitch. The keyswitch is disposed above the optical module and includes a keycap. The vertical projection of the keycap on the mask film at least partially covers the light-transparent region. 
     In an embodiment, the keycap has a light-transparent portion. The plurality of light-shielding sub-regions and the plurality of light-transparent sub-regions are alternatingly arranged along an extending direction of the light-transparent portion. 
     Compared with the prior art, the luminous keyboard and the optical module of the invention not only enhance the brightness of the keyswitches by the edge-lighting characteristics of the light guide sheet, but also incorporate the mask pattern design of the mask film with the patterned layer, so that the luminous keyboard is improved with the lighting uniformity and suitable for the slim border design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic exploded view of the luminous keyboard in an embodiment of the invention. 
         FIG.  2 A  is a schematic cross-sectional view of the keyswitch of the luminous keyboard in a first embodiment of the invention. 
         FIG.  2 B  is a partially enlarged view of  FIG.  2 A . 
         FIG.  2 C  is a top view of  FIG.  2 A , showing the relative position of the outer light-transparent region of the mask film, the patterned layer, and the light-exit edge of the light guide sheet. 
         FIG.  2 D  is a bottom view of  FIG.  2 A  corresponding to  FIG.  2 C . 
         FIG.  2 E  is a top view of the keyswitch of the luminous keyboard in a second embodiment of the invention, showing the relative position of the outer light-transparent region of the mask film, the patterned layer, and the light-exit edge of the light guide sheet. 
         FIG.  3 A  and  FIG.  3 B  are a schematic partially enlarged cross-sectional view and a schematic top view of the keyswitch of the luminous keyboard in a third embodiment of the invention, showing the relative position of the outer light-transparent region of the mask film, the patterned layer, and the light-exit edge and the hole of the light guide sheet. 
         FIG.  3 C  is a variant embodiment of  FIG.  3 B , showing the relative position of the outer light-transparent region of the mask film, the patterned layer, the auxiliary mask pattern, and the light-exit edge and the hole of the light guide sheet. 
         FIG.  4 A  and  FIG.  4 B  are a schematic partially enlarged cross-sectional view and a schematic top view of the keyswitch of the luminous keyboard in a fourth embodiment of the invention, showing the relative position of the outer light-transparent region of the mask film, the patterned layer, and the light-exit edge of the light guide sheet. 
         FIG.  5    is a partially enlarged cross-sectional view of the keyswitch of the luminous keyboard in a fifth embodiment of the invention. 
         FIG.  6    is an exploded plan view, showing components of the optical module in an embodiment of the invention. 
         FIG.  7 A  is a schematic view of the optical module in a sixth embodiment of the invention, showing the relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. 
         FIG.  7 B  is a variant embodiment of  FIG.  7 A , showing a schematic view of another relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. 
         FIG.  8 A  is a schematic view of the optical module in a seventh embodiment of the invention, showing the relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. 
         FIG.  8 B  is a variant embodiment of  FIG.  8 A , showing a schematic view of another relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. 
         FIG.  9 A  is a schematic view of the optical module of the invention, showing the relative position of the light modulation region of the mask film, the patterned layer, and the light-transparent portion of the keycap. 
         FIG.  9 B  is a variant embodiment of  FIG.  9 A . 
         FIG.  10 A  is a schematic view of the optical module in an eighth embodiment of the invention, showing the relative position of the mask pattern of the mask film, the patterned layer, and the light source. 
         FIG.  10 B  is a variant embodiment of  FIG.  10 A . 
         FIG.  11 A  is a schematic view of the optical module in a ninth embodiment of the invention, showing the relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. 
         FIG.  11 B  is a variant embodiment of  FIG.  11 A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention provides a luminous keyboard and an optical module thereof, which promotes the brightness of keyswitches, especially the outer keyswitches, so that the keyswitches can have a stable lighting effect. The luminous keyboard of the invention can be an independent keyboard or integrated into electronic devices (e.g. mobile devices, laptop computers). Specifically, the luminous keyboard can adopt the slim border design, but not limited thereto. Hereinafter, an independent computer keyboard (shown in  FIG.  1   ) is illustrated as an example. 
     As shown in  FIG.  1   , in an embodiment, the luminous keyboard  1  includes an optical module  10  and a keyswitch module  20 . The optical module  10  is disposed under the keyswitch module  20 . The keyswitch module  20  includes a plurality of keyswitches  200 , and the plurality of keyswitches  200  includes at least one outer keyswitch  201  and at least one inner keyswitch  202 . In one aspect, the plurality of keyswitches  200  are arranged in multiple rows along the Y-axis direction. The outmost keyswitches in each row, such as two keyswitches respectively at two ends in the X-axis direction, can be the outer keyswitches  201 , and the keyswitches between the outer keyswitches  201  at the two ends can be the inner keyswitches  202 . In another aspect, among the multiple rows of keyswitches arranged along the Y-axis direction, the keyswitches in the outmost rows (e.g. the topmost and bottommost rows in the Y-axis direction) can be the outer keyswitches  201 , and the keyswitches between the outer keyswitches  201  in the outmost rows can be the inner keyswitches  202 . In other words, the outer keyswitches  201  are not adjacent to other keyswitches by at least one side, such as the keyswitches disposed around the outer perimeter, and the inner keyswitches  202  are surrounded by other keyswitches at all sides. In this embodiment, the left edges of the outer keyswitches  201  at the left side (e.g. the left edges of the keycaps) are aligned along the Y-axis direction, and the right edges of the outer keyswitches  201  at the right side (e.g. the right edges of the keycaps) are aligned along the Y-axis direction, but not limited thereto. Moreover, the upper edges of the outer keyswitches  201  at the topmost row (e.g. the upper edges of the keycaps) are aligned along the X-axis direction, and the lower edges of the outer keyswitches  201  at the bottommost row (e.g. the lower edges of the keycaps) are aligned along the X-axis direction, but not limited thereto. 
     Specifically, the keyswitch  200  can be any suitable key unit with light-transparent keycap. The light-transparent keycap can be a keycap with one or more light-transparent portions or an entire keycap of light-transparent.  FIG.  2 A  is a schematic cross-sectional view of the keyswitch of the luminous keyboard of a first embodiment of the invention. As shown in  FIG.  2 A , in an embodiment, the keyswitch (e.g. the outer keyswitch  201  at the left side) includes the scissors-like support mechanism  230  movably coupled with the keycap  220  and the baseplate  210  to support the keycap  220  to move relative to the baseplate  210  and compress the rubber dome  250  to trigger the switch layer  240  (e.g. membrane switch), and the rubber dome  250  provides the restoring force to enable the keycap  220  to return to its original position, but not limited thereto. In other embodiments, the scissors-like support mechanism  230  can be replaced with other up-down support mechanisms, such as butterfly-type support mechanism, sliding block support mechanism, cantilever support mechanism. The rubber dome  250  can be replaced with other restoring units, such as magnets, spring. Moreover, the switch layer  240  can be replaced with other switch units, such as mechanical switch, optical switch, magnetic switch. That is, the keyswitches  200  of the keyswitch module  20  can have any suitable configuration, which can generate the triggering signal after being pressed. 
     Referring to  FIG.  1    again, the optical module  10  includes a mask film  110 , a patterned layer  120 , and a light guide sheet  130 . The mask film  110  has a mask pattern  112 . The mask pattern  112  defines a plurality of light-transparent regions  114 , and the plurality of light-transparent regions  114  correspond to the plurality of keyswitches  200 , respectively. For example, the plurality of light-transparent regions  114  includes outer light-transparent regions  114 A and inner light-transparent regions  114 B. The outer light-transparent regions  114 A correspond to the outer keyswitches  201 . For example, the outer light-transparent regions  114 A correspond to the outer keyswitches  201  at the left side along the Z-axis direction. The inner light-transparent regions  1146  correspond to the inner keyswitches  202 . For example, the inner light-transparent regions  1146  correspond to the inner keyswitches  202  along the Z-axis direction. The outer light-transparent region  114 A has a region boundary  116 . For example, the region boundary  116  of the outer light-transparent region  114 A at the left side is the left boundary extending along the Y-axis direction, and the region boundary  116  of the outer light-transparent region  114 A at the right side is the right boundary extending along the Y-axis direction. Specifically, the mask film  110  is disposed on one side of the light guide sheet  130  and has the mask pattern  112  to selectively allow light to pass therethrough and block light. For example, the mask film  110  can be a light-transparent optical film (e.g. polyethylene terephthalate (PET) film) with light-blocking material (e.g. ink) disposed thereon to form the mask pattern  112 , so as to allow light to pass through the light-transparent regions  114  and block light at locations where the keyswitch module  20  does not require light, such as the gap between the keyswitches  200 . In an embodiment, the shape and size of the mask film  110  preferably correspond to those of the baseplate  210  of the keyswitch module  20 , but not limited thereto. 
     The patterned layer  120  is disposed on the mask film  110 . The patterned layer  120  has a light transmittance larger than a light transmittance of the mask pattern  112  and smaller than a light transmittance of each of the plurality of light-transparent regions  114 . The patterned layer  120  is preferably formed by printing a light blocking material in a predetermined pattern. The patterned layer  120  can be printed on a separate light-transparent film or printed on the mask film  110 . For example, the patterned layer  120  is preferably printed on a surface of the mask film  110  that faces the light guide sheet  110 , but not limited thereto. According to practical applications, the patterned layer  120  and the mask pattern  112  can be printed on the same surface or different surfaces of the mask film  110 . In an embodiment, the patterned layer  120  can define a plurality of light-permeable regions  124 , and the plurality of light-permeable regions  124  are disposed corresponding to the plurality of light-transparent regions  114  (and the keyswitches  200 ). For example, the plurality of light-permeable regions  124  includes outer light-permeable regions  124 A and inner light-permeable regions  124 B. The outer light-permeable regions  124 A correspond to the outer light-transparent regions  114 A and the outer keyswitches  201  along the Z-axis direction. The inner light-permeable regions  124 B correspond to the inner light-transparent regions  114 B and the inner keyswitches  202  along the Z-axis direction. The outer light-permeable region  124 A has a layer boundary  126 . For example, the layer boundary  126  of the outer light-permeable region  124 A at the left side is the left boundary extending along the Y-axis direction, and the layer boundary  126  of the outer light-permeable region  124 A at the right side is the right boundary extending along the Y-axis direction. Specifically, the patterned layer  120  is disposed on one side of the light guide sheet  130 , such as at the same side as the mask film  110 , and the patterned layer  120  can selectively partially block light or allow light to pass therethrough. The patterned layer  120  has a light transmittance larger than the light transmittance of the mask pattern  112 . For example, the patterned layer  120  can be a light-transparent optical film (e.g. PET film) with light-blocking material disposed thereon to form the patterned layer  120 . Alternatively, the patterned layer  120  can be formed by printing the light blocking material on the mask film  110  to omit the additional light-transparent optical film. In other words, the patterned layer  120  and the mask pattern  112  can be formed on the same light-transparent optical film, so that the mask film  110  has not only the mask pattern  112 , but also the patterned layer  120  thereon. The light blocking material adapted to form the patterned layer  120  has the light transmittance larger than that of the light blocking material adapted to form the mask pattern  112  and smaller than that of the light-transparent optical film of the mask film  110 . For example, the light blocking material adapted to form the mask pattern  112  can be the black ink, and the light blocking material adapted to form the patterned layer  120  can be ink of any suitable color other than black, such as white ink. As such, when light illuminates on the mask pattern  112 , the patterned layer  120 , and the light-transparent region  114  (or the light-permeable region  124 ), the mask pattern  112  substantially completely blocks the light (i.e., no light passing therethrough), the patterned layer  120  blocks a portion of the light (i.e., part of the light passing therethrough and part of the light being blocked), and the light-transparent region  114  (or the light-permeable region  124 ) substantially allows all of the light to pass therethrough. It is noted that according to practical applications, the patterned layer  120  can be locally disposed on the mask film  110  without forming the light-permeable regions  124 , which correspond to the light-transparent region  114 . In other words, the patterned layer  120  can be formed at any suitable location of the mask film  110  in any suitable pattern to adjust the local light transmittance or brightness. 
     The light guide sheet  130  is disposed on one side of the mask film  110 , such as the lower side. The light guide sheet  130  has a light-exit edge  132 , such as the edge of the light-exit surface. The light-exit edge  132  corresponds to the region boundary  116 , so that the vertical projection of the light-exit edge  132  of the light guide sheet  130  on the mask film  110  at least partially falls within the outer light-transparent region  114 A. Specifically, the light guide sheet  130  can be a film-like or sheet-like plate, which can be made of any suitable optical materials, such as optical polymers. The size of the light guide sheet  130  is slightly smaller than that of the mask film  110 , and the light guide sheet  110  has a light-output surface  138  corresponding to the plurality of light-transparent regions  114  (and light-permeable regions  124 ). For example, the size of the light guide sheet  130  in the X-axis direction is preferably smaller than that of the mask film  110 , so that the edge of the mask film  110  extends beyond the light-exit edge  132  of the light guide sheet  130 , facilitating the adhesion with other components, such as the reflective film  150 , the baseplate  210 . In an embodiment, the light-exit edge  132  of the light guide sheet  130  defines the boundary of the light-output surface  138  in the X-axis direction. In this embodiment, the light guide sheet  130  has a plurality of light source holes  134 , and the lateral surface inside the light source hole  134  can be the light-input surface of the light guide sheet  130 . The top surface of the light guide sheet  130  (i.e., the upper surface that extends along the X-Y plane) can be the light-output surface  138  of the light guide sheet  130 . Light enters the light guide sheet  130  from the light-input surface, travels along the extension direction of the light guide sheet (e.g. along the X-axis and Y-axis directions) through the total reflection, and then emits out from the plurality of light-transparent regions  114  (and the light-permeable regions  124 ) of the mask film  110 . 
     As shown in  FIG.  2 A , in an embodiment, the optical module  10  includes one or more light sources  140 , which provides light into the light guide sheet  130 . As such, the optical module  10  can be a backlight module of the luminous keyboard  1 . Specifically, the light source  140  is preferably a light-emitting diode (LED), such as a side-lighting LED, but not limited thereto. The light source  140  is disposed in the light source hole  134 , so that the light-emitting surface preferably faces the light-input surface of the light guide sheet  130 , and the light enters the light guide sheet  130  from the light-input surface. In an embodiment, a plurality of light sources  140  is preferably integrated on a circuit board to form an integrated light source unit, so as to enhance the assembly efficiency. 
     Moreover, as shown in  FIG.  1   , the optical module  10  can optionally include a reflective film  150 . The reflective film  150  is disposed on one side of the light guide sheet  130  opposite to the mask film  110 , such as the lower side of the light guide sheet  130 . The reflective film  150  is configured to reflect the light emitting from the lower surface of the light guide sheet  130  back to the light guide sheet  130 . Specifically, the reflective film  150  can be a reflective film made of reflective materials (e.g. metal foil), a layer of reflective material coated on a non-reflective film, or a plastic film doped with reflective particles (e.g. PET film doped with reflective particles). The shape and size of the reflective film  150  preferably correspond to those of the mask film  110 , and the malleability/deformability of the reflective film  150  is preferably larger than that of the mask film  110 . In other words, the reflective film  150  is much more deformable than the mask film  110  is, so that the reflective film  150  is readily to be adhered. 
     As shown in  FIGS.  2 A and  2 B ,  FIG.  2 B  is a partially enlarged view of  FIG.  2 A , and  FIG.  2 B  just shows the optical module  10  and the baseplate  210  of the keyswitch module  20  and omits the components (e.g. switch layer  240 , rubber dome  250 , scissors-like support mechanism  230 , and the keycap  220 ) on the baseplate  210 . The upper surface of the end portion of the mask film  110  is adhered to the lower surface of the baseplate  210 , and the lower surface of the end portion of the mask film  110  is adhered to the upper surface of the reflective film  150 , so that the light guide sheet  130  is enclosed between the mask film  110  and the reflective film  150  to prevent lateral light leakage. Specifically, as shown in  FIG.  2 B , the mask pattern  112  on the upper surface of the end portion of the mask film  110  is adhered to the lower surface of the baseplate  210 , and the patterned layer  120  on the lower surface of the end portion of the mask film  110  is adhered to the reflective film  150 , so that the light guide sheet  130  is enclosed between the mask film  110  and the reflective film  150 , but not limited thereto. In this embodiment, the keycap  220  of the outer keyswitch  201  and the baseplate  210  can be flushed with the edge of the optical module  10 . For example, the left edges of the keycap  220 , the baseplate  210 , the mask film  110 , and the reflective film  150  are preferably aligned with each other along the stacking direction (e.g. the Z-axis direction) to facilitate the slim border design of the luminous keyboard  1 . Specifically, in the slim border design, the size and shape of the inner light-transparent region  114 B is preferably consistent with those of its corresponding keycap  220 , i.e., the vertical projections of the inner light-transparent region  114 B and the keycap  220  on the baseplate  210  substantially completely overlap with each other. The size and shape of the outer light-transparent region  114 A (and the light-permeable region  124 A) are limited by the considerations of adhesion requirements and lateral light leakage, so the size of the outer light-transparent region  114 A (and the light-permeable region  124 A) is smaller than its corresponding keycap  220 . For example, the outer light-transparent region  114 A (and the light-permeable region  124 A) is retreated from the edge of the mask film  110  by a predetermined width in the X-axis direction. In an embodiment, the adhesion width D1 of the reflective film  150  and the mask film  110 , such as the adhesion distance along the X-axis direction from the edge, is preferably equal to or larger than 1.5 mm, to reduce the possibility of light leakage due to the detachment of the reflective film  150  and the mask film  110  of the optical module  10  as the luminous keyboard  1  adopts the slim border design. In other words, for a single side, the size of the outer light-transparent region  114 A in the X-axis is shorter than that of its corresponding keycap  220  by at least 1.5 mm. For the outer light-transparent regions  114 A at both sides, the size of the light guide sheet  130  in the X-axis direction is shorter than that of the mask film  110  by at least 3.0 mm (=2×1.5 mm), but not limited thereto. 
     Specifically, in the slim-border design, the inner light-transparent region  1146  and the inner light-permeable region  124 B preferably correspond to each other in size and shape. In other words, the vertical projections of the inner light-transparent region  1146  and corresponding inner light-permeable region  124 B on the baseplate  210  preferably substantially completely overlap with each other, but not limited thereto. In another embodiment, the inner light-transparent region  114 B can be slightly larger than the inner light-permeable region  124 B according to practical applications. The size and shape of the outer light-transparent region  114 A and the outer light-permeable region  124 A are limited by the considerations of adhesion requirements and lateral light leakage, so the size of the outer light-permeable region  124 A is smaller than its corresponding outer light-transparent region  114 A. For example, the outer light-permeable region  124 A extends beyond the region boundary  116  by a predetermined width in the X-axis direction. In an embodiment, a distance between one side of the outer light-permeable region  124 A and one side of the outer light-transparent region  114 A is defined as D2 (e.g. a distance from the region boundary  116  to the layer boundary  126  in the X-axis direction), and the distance D2 is preferably 1 mm to 3 mm, to reduce the possibility of light leakage due to the detachment of the reflective film  150  and the mask film  110  of the optical module  10  as the luminous keyboard  1  adopts the slim border design. In other words, for a single side, the size of the outer light-transparent region  114 A is retreated from its corresponding outer light-permeable region  124 A toward the edge by 1 mm to 3 mm in the X-axis direction, but not limited thereto. 
     Referring to  FIGS.  2 C and  2 D ,  FIG.  2 C  is a top view of  FIG.  2 A  and shows the relative position of the outer light-transparent region  114 A of the mask film  110 , the patterned layer  120 , and the light-exit edge  132  of the light guide sheet  130 .  FIG.  2 D  is a bottom view of  FIG.  2 A  corresponding to  FIG.  2 C  and shows the relative position of the patterned layer  120  and the light-exit edge  132  of the light guide sheet  130 . In this embodiment, the patterned layer  120  is at least partially located in the outer light-transparent region  114 A adjacent to the region boundary  116 . The patterned layer  120  (or the vertical projection thereof on the mask film  110 ) extends from the region boundary  116  into the outer light-transparent region  114 A to define the layer boundary  126 , and the vertical projection of the light-exit edge  132  of the light guide sheet  130  on the mask film  110  is located between the region boundary  116  and the layer boundary  126 . In other words, the patterned layer  120  at least partially extends beyond the region boundary  116  into the light-transparent region  114 A, and the portion of the patterned layer  120  extending into the light-transparent region  114 A forms a strip region  128 . The strip region  128  extends along the region boundary  116 , and the vertical projection of the light-exit edge  132  of the light guide sheet  130  on the mask film  110  (or the patterned layer  120 ) at least partially falls within the strip region  128 . The layer boundary  126  and the region boundary  116  are located at opposite sides with respect to the light-exit edge  132  in the X-axis direction. The vertical projection of the light-exit edge  132  on the mask film  110  at least partially falls within the outer light-transparent region  114 A and overlaps with the portion of the patterned layer  120  extending into the outer light-transparent region  114 A (e.g. the strip region  128 ), so that the lateral surface (or end surface) of the light guide sheet  130  adjacent to the light-exit edge  132  can serve as a light-output surface to enhance the brightness of the outer keyswitch  201 . The light-exit edge  132  can extend substantially parallel to the region boundary  116 , but is not limited thereto. As shown in  FIG.  2 D , the patterned layer  120  partially overlaps the mask pattern  112  and extends from the region boundary  116  into the outer light-transparent region  114 A, so the portion of the patterned layer  112  located in the outer light-transparent region  114 A does not overlap the mask pattern  112 , but not limited thereto. In another embodiment, the patterned layer  120  can be located only in the outer light-transparent region  114 A without overlapping the mask pattern  112 . As such, when a portion of the outer light-transparent region  114 A becomes locally brighter due to the light emitting from the light-exit edge  132  of the light guide sheet  130 , the portion of the patterned layer  120  in the outer light-transparent region  114 A can correspondingly adjust the brightness of the outer light-transparent region  114 A. 
       FIG.  2 E  is a top view of the keyswitch of the luminous keyboard in a second embodiment of the invention, showing the relative position of the mask film  110 , the patterned layer  120 , and the light guide sheet  130 . For example, the vertical projection of the light-exit edge  132  on the mask film  110  is located outside the outer light-transparent region  114 A and overlaps the at least a portion of the patterned layer  120 .  FIG.  2 E  is a variant embodiment of  FIG.  2 C . In this embodiment, at least a portion of the patterned layer  120  does not overlap the mask pattern  112  and is adjacent to the outer light-transparent region  114 A, so as to define the region boundary  116  of the outer light-transparent region  114 A together with the mask pattern  112 . Specifically, in an embodiment, the patterned layer  120  is disposed on the mask film  110  around the corner of the outer light-transparent region  114 A, such as around the upper left corner of the outer light-transparent region  114 A, and the vertical projection of the light-exit edge  132  partially falls on the portion of the patterned layer  120  which does not overlap the mask pattern  112 . As such, with the arrangement of the patterned layer  120 , the brightness at the corner of the outer light-transparent region  114 A can be enhanced, and the uniformity of light distribution in the outer keyswitch  201  can be improved. In other words, the patterned layer  120  can be disposed at any place around or in the outer light-transparent region  114 A where the brightness is required to be modulated. For example, to increase the brightness, the patterned layer  120  can be disposed to replace a portion of the mask pattern  112 , so as to increase the light transmittance around the corresponding portion. To decrease the brightness, the patterned layer  120  can be disposed in the light-transparent region  114  (e.g. the outer light-transparent region  114 A), so as to block a portion of light at the corresponding portion. Moreover, the patterned layer  120  can be disposed to replace a portion of the mask pattern  112  and also disposed in the light-transparent region  114  to improve the uniformity of brightness of the light-transparent region  114 . For example, in this embodiment, the patterned layer  120  is illustrated to replace a portion of the mask pattern  112  at the left corner around the outer light-transparent region  114 A and define the region boundary  116  with the mask pattern  112 , but not limited thereto. According to practical applications, the patterned layer can further extend into the outer light-transparent region  114 A, so the patterned layer  120  not only replaces a portion of the mask pattern  112  around the outer light-transparent region  114 A, but also extends into the outer light-transparent region  114 A. 
       FIG.  3 A  and  FIG.  3 B  are a schematic partially enlarged cross-sectional view and a schematic top view of the keyswitch (e.g. outer keyswitch  201 ) of the luminous keyboard in a third embodiment of the invention, showing the relative position of the outer light-transparent region  114 A of the mask film  110 , the patterned layer  120 , and the light-exit edge  132  and the hole  136  of the light guide sheet  130 . As shown in  FIGS.  3 A and  3 B , in this embodiment, the light guide sheet  130  can have one or more holes  136 , and a vertical projection of the hole  136  on the mask film  110  falls in the outer light-transparent region  114 A. Moreover, in this embodiment, the vertical projection of the light-exit edge  132  of the light guide sheet  130  on the mask film  110  is farther away from the region boundary  116  than the layer boundary  126  is. With such a configuration, the hole  136  is configured to allow a portion of light emitted therefrom to improve local brightness of the outer light-transparent region  114 A and attenuate the intensity of light emitted from the light exit edge  132 . The patterned layer  120  in the outer light-transparent region  114 A is configured to further modulate the brightness of the outer light-transparent reign  114 A adjacent to the light exit edge  132 , so as to improve the uniformity of brightness of the outer keyswitch  201 . The hole  136  is preferably located corresponding the light-transparent portion of the keycap (e.g. the alphanumeric portion) at a farther side with respect to the light-exit edge  132 , and the shape, size, and number of the hole  136  can be modified according to practical applications, not limited to the embodiment. 
       FIG.  3 C  is a variant embodiment of  FIG.  3 B , showing the relative position of the outer light-transparent region  114 A of the mask film  110 , the patterned layer  120 , the auxiliary mask pattern  122 , and the light-exit edge  132  and the hole  136  of the light guide sheet  130 . In this embodiment, the mask layer  120  further includes an auxiliary mask pattern  122 . The auxiliary mask pattern  122  is disposed within the outer light-transparent region  114 A, and the vertical projection of the hole  136  of the light guide sheet  130  on the mask film  110  at least partially overlaps with the auxiliary mask pattern  122 . Specifically, the auxiliary mask pattern  122  can be a patterned coating on the mask film  110 . The auxiliary mask pattern  122  can modulate the light intensity at the location corresponding to the hole  136  of the light guide sheet  130 , so that the intensity of light emitting from the hole  136  can be controlled. For example, the auxiliary mask pattern  122  can be a strip or any pattern of suitable shape, which is located at the side of the hole  136  perpendicular to the light-exit edge  132 . For example, two strips (e.g. the auxiliary mask pattern  122 ) are arranged along the Y-axis direction at two opposite sides of the hole  136 . Moreover, the auxiliary mask pattern  122  can be a coating layer, which is configured to attenuate the light emitting from the hole  136 , or a reflective coating, which is configured to reflect the light emitting from the through hole  136  toward the reflective film  150 , so as to enhance the scattering of light and the lighting uniformity. The auxiliary mask pattern  122  preferably has a light transmittance larger than or equal to the light transmittance of the mask pattern  112 . For example, the auxiliary mask pattern  122  can be formed by the same light-blocking material which forms the mask pattern  112  and printed together with the mask pattern  112  on the light-transparent film of the mask film  110 , but not limited thereto. In another embodiment, the auxiliary mask pattern  122  can be formed by the same light-blocking material which forms the patterned layer  120  and printed together with the patterned layer  120  on the light-transparent film of the mask film  110 . According to practical applications, the auxiliary mask pattern  122  can be formed by any suitable light-blocking material other than those for forming the mask pattern  112  and the patterned layer  120 . 
       FIG.  4 A  and  FIG.  4 B  are a schematic partially enlarged cross-sectional view and a schematic top view of the keyswitch of the luminous keyboard in a fourth embodiment of the invention, which are a variant embodiment corresponding to  FIGS.  2 B and  2 C . Hereinafter, the differences between this embodiment and the previous embodiments will be explained, and other details can refer to the related descriptions of the previous embodiments and will not elaborate again. As shown in  FIGS.  4 A and  4 B , in this embodiment, the patterned layer  120  (or the vertical projection thereof on the mask film) extends beyond the region  116  boundary into the outer light-transparent region  114 A to form the strip region  128 . The strip region  128  extends along the region boundary  116 , and the layer boundary  126  is located between the region boundary  116  and the light-exit edge  132  in the X-axis direction. The vertical projection of the light-exit edge  132  of the light guide sheet  130  on the mask film  110  falls outside the strip region  128 , i.e., not overlaps with the strip region  128 . The vertical projection of the light-exit edge  132  on the mask film  110  at least partially falls within the outer light-transparent region  114 A and is not parallel to the region boundary  116 . In other words, the light guide sheet  130  is not only smaller than the mask film  110  (and the patterned layer  120 ) in the X-axis direction, but the size of the light guide sheet  130  is so small that the edge of the light guide sheet  130  (i.e., light-exit edge  132 ) is retreated to the inner side of the region boundary  116  (and the layer boundary  126 ). As such, when the light guide sheet  130  and the mask film  110  with the patterned layer  120  are stacked together, in the X-axis direction, a gap G exists between the light-exit edge  132  and the layer boundary  126 , and the gap G varies along the Y-axis direction. In other words, the light-exit edge  132  extends non-linearly along the Y-axis direction (or does not extend parallel to the region boundary  116  and/or the layer region  126 ), so that the gap G is not a constant value in the Y-axis direction. 
     In an embodiment, in the extending direction (e.g. the Y-axis direction) of the region boundary  116 , the vertical projection of the light-exit edge  132  is concave with respect to the region boundary  116 . In other words, the gap G at the position closer to two ends of the region boundary  116  along the Y-axis direction is smaller, and the gap G at the position closer to the center of the region boundary  116  in the Y-axis direction is larger. In such a configuration, part of the light can emit out earlier from the light-exit edge  132  of the light guide sheet  130 , so that the light which is emitted from the lateral surface adjacent to the light-exit edge  132  is prevented from being too concentrated, thereby improving the lighting uniformity. The shape of the light-exit edge  132  can be modified according to the light energy required in practical applications, for example (but not limited to), a curve shape, a stepped shape, a zigzag shape, or any suitable shape. 
       FIG.  5    is a partially enlarged cross-sectional view of the keyswitch of the illuminous keyboard in a fifth embodiment of the invention, and  FIG.  5    is a schematic view similar to  FIG.  2 B . Hereinafter, the differences between this embodiment and the above embodiments will be explained, and other details can refer to the related descriptions of the previous embodiments and will not elaborate again. As shown in  FIG.  5   , in this embodiment, a mask portion  152  is disposed between the reflective film  150  and the light guide sheet  130 , and the mask portion  152  is adjacent to the light-exit edge  132 . The vertical projection of the mask portion  152  on the mask film  110  preferably at least partially overlaps the patterned layer  120 . Specifically, in an embodiment, the mask portion  152  can be an adhesive layer disposed between the reflective film  150  and the light guide sheet  130  along the light-exit edge  132  and configured to absorb the light energy to attenuate the light intensity to enhance the lighting uniformity. In another embodiment, the mask portion  152  can be a mask coating (or mask pattern), which is coated on the reflective film  150  along the light-exit edge  132  and configured to locally reduce the reflective effect of the reflective film  150 , so as to attenuate the light intensity to enhance the lighting uniformity. 
       FIG.  6    is an exploded plan view, showing components of the optical module  10  in an embodiment of the invention, which is a schematic view similar to  FIG.  1   . Hereinafter, the differences between this embodiment and the previous embodiments will be explained, and other details can refer to the related descriptions of the previous embodiments and will not elaborate again. As shown in  FIG.  6   , in this embodiment, the size of the light guide sheet  130  corresponds to the size of the keyswitch module  20  and is slightly smaller than that of the mask film  110  (and the patterned layer  120 ). For example, the size of the light guide sheet  130  in the X-axis direction and/or the Y-axis direction is preferably smaller than the size of the mask film  110 , so that the edge of the mask film  110  (and the patterned layer  120 ) extend beyond the light guide sheet  130 , facilitating the adhesion with other components, such as the reflective film  150 , the baseplate  210 , but not limited thereto. 
     In an embodiment, the mask pattern  112  of the mask film  110  defines one or more light-transparent regions  114 , a light-shielding region  113 , and one or more light modulation regions  118 . In this embodiment, the patterned layer  120  is preferably disposed on the mask film  110 . The patterned layer has a light transmittance larger than a light transmittance of the light-shielding region  113  and smaller than a light transmittance of the light-transparent region  114 . At least a portion of the patterned layer  120  is located the light modulation region  118 , so the light modulation region  118  has an average light transmittance per unit area smaller than that of the light-transparent region  114  and larger than that of the light 0 shielding region  113 . 
     For example, the mask pattern  112  is a pattern formed on the light-transparent optical film by disposing the light-blocking material thereon. The light-transparent region  114  is a region of the light-transparent optical film without the light-blocking material disposed thereon, and the light-shielding region  113  is a region of the light-transparent optical film with the light-blocking material disposed thereon. The light modulation region  118  extends from the light-shielding region  113  to the light-transparent region  114  to at least partially modulate the light energy between the light-shielding region  113  and the light-transparent region  114 . In this embodiment, the mask pattern  112  defines a plurality of light-transparent regions  114 , and the plurality of light-transparent regions  114  correspond to the plurality of keyswitches  200 , respectively. For example, the number, location, and shape of the light-transparent regions  114  preferably correspond to those of the keyswitches  200 , but not limited thereto. The light modulation region  118  can be selectively disposed at location corresponding to one or more keyswitches that require light modulation. For example, when the outer keyswitches  201  at the topmost row require light modulation, the light modulation regions  118  can be disposed along the X-axis direction to respectively correspond to the light-transparent regions  114 , and the patterned layer  120  can be disposed on the mask film  110  to extend along the Y-axis direction into the light modulation region  118 . The light-transparent region  114  allows light to pass therethrough. The light-shielding region  113  substantially blocks light. The light modulation region  118  partially allows light to pass therethrough and partially blocks light. Hereinafter, referring to  FIGS.  7 A to  11 B , various embodiments of the configuration of the mask pattern of the mask film for a single keyswitch will be illustrated. 
       FIG.  7 A  is a schematic view of the optical module in a sixth embodiment of the invention. As shown in  FIG.  7 A , in an embodiment, the light-shielding region  113  partially surrounds the light-transparent region  114  to form a boundary line  115  between the light-shielding region  113  and the light-transparent region  114 , and two ends  115   a ,  115   b  of the boundary line  115  are substantially connected to middle sections of two opposite sides of the light modulation region  118 . For example, the light-shielding region  113  can be considered as surrounding and adjoining the light-transparent region  114  to substantially form a rectangular boundary line  115 , and the light modulation region  118  extends between the light-shielding region  113  and the light-transparent region  114  across a portion of the boundary line  115 , so that the middle sections of both sides of the light modulation region  118  are respectively connected to the two ends  115   a  and  115   b  of the boundary line  115 . In an embodiment, the light modulation region  118  includes a plurality of light-shieling sub-regions  1182  and a plurality of light-transparent sub-regions  1184 . The patterned layer  120  is disposed in the light modulation region  118  and extends into the light-shielding region  113 . In an embodiment, the light-shieling sub-regions  1182  and the light-transparent sub-regions  1184  can be formed by the same light-blocking material of the light-shielding region  113 , and at least a portion of the patterned layer  120  is disposed in the light-transparent sub-regions  1184  to form a plurality of patterned sub-regions  1201 . In other words, the plurality of light-shieling sub-regions  1182  can be considered as a plurality of protrusions of the mask pattern  112 , which is spaced apart and disposed along the boundary line  115  (or the region boundary  116 ), and the protrusions extend beyond the light-exit edge  132  across the boundary line  115  into the vertical projection of the light guide sheet  130  on the mask film  110 . The patterned layer  120  (or the vertical projection thereof on the mask film  110 ) at least partially fills the space between adjacent two protrusions. Moreover, the plurality of patterned sub-region  1201  is disposed at one end of the plurality of light-transparent sub-regions  1184 , such as the end adjacent to the light-shielding region  113  and away from the light-transparent region  114 . The plurality of light-shielding sub-regions  1182  and the plurality of light-transparent sub-regions  1184  are alternatingly disposed, for example, along the edge  132  of the light guide sheet  130  or along the extending direction of the boundary line  115 . Specifically, the plurality of light-shielding sub-regions  1182  are the regions where the light-shielding material is disposed in the light modulation region  118 , and the plurality of light-transparent sub-regions  1184  are the regions where the light-shielding material is not disposed in the light modulation region  118 . In other words, in the mask film  110 , the light-shielding material is disposed at the light-shielding region  113  (e.g. gaps between adjacent keyswitches or border of the keyboard) and the plurality of light-shielding sub-regions  1182  to constitute the mask pattern  112 . In an embodiment, each of the plurality of light-shielding sub-regions  1182  has a first end and a second end opposite to the first end. The first end is connected to the light-shielding region  113  adjacent to the patterned sub-regions  1201 , and the second end extends to the light-transparent region  114 . In this embodiment, the patterned sub-regions  1201  is disposed between adjacent light-shielding sub-regions  1182  near the first end. In an embodiment, the plurality of light-shielding sub-regions  1182  may have a same shape and a same size, and each light-shielding sub-region  1182  extends from the light-shielding region  113  through the patterned layer  120  to the light-transparent region  114 , but not limited thereto. According to practical applications, the shape, size, and number of the light-shielding sub-regions  1182  may be different. 
     In this embodiment, the light-shielding sub-region  1182  has a triangle shape, so that the width of the first end of the light-shielding sub-region  1182  (i.e., the end adjacent to the light-shielding region  113 ) is larger than that of the second end (i.e., the end adjacent to the light-transparent region  114 ), and the width of the light-shielding sub-region  1182  is gradually reduced from the light-shielding region  113  to the light-transparent region  114 . In other words, the wider bottom side of the triangular light-shielding sub-region  1182  is connected to the light-shielding region  113 , and the light-shielding sub-region  1182  extends across the virtual connecting line between the two ends  115   a  and  115   b  of the boundary line  115 , so that the vertex point of the triangular light-shielding sub-region  1182  points into the light-transparent region  114 . The triangular light-shielding sub-regions  1182  are arranged along the edge  132  of the light guide sheet  130 , so that one triangular light-transparent sub-region  1184  is located between two adjacent light-shielding sub-regions  1182 , or one triangular light-shielding sub-region  1182  is located between two adjacent light-transparent sub-regions  1184 . Correspondingly, the light-transparent sub-region  1184  has a similar triangular shape, so that the wider bottom side of the triangular light-transparent sub-region  1184  is proximate to the light-transparent region  114 , and the vertex of the triangular light-transparent sub-region  1184  is proximate to the light-shielding region  113 . In such a configuration, each of the plurality of light-shielding sub-regions  1182  has a gradually reduced width, so a width of each of the plurality of light-transparent sub-regions  1184  and a width of the portion of the patterned layer  120  in each of the light-transparent sub-regions  1184  (i.e., the patterned sub-region  1201 ) are gradually increased from the light-shielding region  113  toward the light-transparent region  114 . As such, the light modulation region  118  has an average light transmittance per unit area larger than that of the light-shielding region and smaller than that of the light-transparent region. Specifically, in this embodiment, the average light transmittance per unit area of the light modulation region  118  is increased from the light-shielding region  113  to the light-transparent region  114 . For example, “the average light transmittance per unit area of the light modulation region  118  is increased from the light-shielding region  113  to the light-transparent region  114 ” is referred to that the width of the light-transparent sub-region  1184  is increased from the light-shielding region  113  to the light-transparent region  114 , or the area ratio of the light-transparent sub-region  1184  to the light-shielding sub-region  1182  (i.e. ratio of light-transmitting area of the light modulation region  118 ) is increased from the light-shielding region  113  to the light-transparent region  114 . When the mask film  110  with the patterned layer  120 , the light guide sheet  130 , and the reflective film  150  are stacked on one another, the vertical projection of the edge  132  of the light guide sheet  130  on the mask film  110  at least partially falls within the light modulation region  118 . As such, the light-shielding sub-regions  1182  of the light modulation region  118  shield the light emitted from the edge  132  of the light guide sheet  130 , and the light-transparent sub-regions  1184  of the light modulation region  118  allow the light emitted from the edge  132  of the light guide sheet  130  to pass therethrough, so that the light emitted from the edge  132  of the light guide sheet  130  can be modulated by the mask film  110 . The patterned layer  120  is disposed at appropriate position in the light modulation region  118  to further locally modulate the light transmittance of the light modulation region  118 , so as to improve the lighting uniformity of the keyswitch and enhance the applicability of the slim border design to keyboards. 
     As shown in  FIG.  7 B , in a variant embodiment, the relative position of the mask pattern  112  of the mask film  110 , the patterned layer  120 , and the light guide sheet  130  is illustrated. In this embodiment, the mask pattern  112  of the mask film  110  defines the light-transparent region  114 , the light-shielding region  113 , and the light modulation region  118  similar to those of  FIG.  7 A . The difference between  FIG.  7 B  and  FIG.  7 A  is in that when the mask film  110  (with the patterned layer  120 ), the light guide sheet  130 , and the reflective film  150  are stacked on one another, the vertical projection of the edge  132  of the light guide sheet  130  on the mask film  110  at least partially falls within the light-shielding region  113  adjacent to the light modulation region  118 . As such, the light-shielding region  113  of the mask film  110  substantially fully shields the light emitted from the edge  132  of the light guide sheet  130 , and the light-transparent sub-regions  1184  of the light modulation region  118  and the patterned sub-regions  1201  of the patterned layer  120  allow a portion of light emitted from the light guide sheet  130  to pass therethrough, so as to modulate the lighting uniformity. In other words, the distance (or relative position) between the edge  132  of the light guide sheet  130  and the light modulation region  118  can be modified according to practical lighting effects. When it requires to utilize more light emitted from the edge  132  of the light guide sheet  130 , a design similar to  FIG.  7 A  can be adopted, otherwise a design similar to  FIG.  7 B  can be adopted. 
     As shown in  FIGS.  8 A and  8 B , the mask pattern  112  of the mask film  110  in a seventh embodiment is illustrated. The light modulation region  118  includes a plurality of light-transparent sub-regions  1184  and a plurality of light-shielding sub-regions  1182 . The plurality of light-transparent sub-regions  1184  and the plurality of light-shielding sub-regions  1182  are alternatingly disposed along the edge  132  of the light guide sheet  130  (or along the extending direction of the boundary line  115 ). Hereinafter, the differences between the embodiments and the previous embodiments will be explained, and other details can refer to the related descriptions of the previous embodiments and will not elaborate again. In this embodiment, the light-shielding region  1182  is in the form of rectangle, so that the width of the first end is equal to the width of the second end. The plurality of light-shielding sub-regions  1182  is disposed at intervals along the edge  132  of the light guide sheet  130 , so that one light-transparent sub-region  1184  is located between two adjacent light-shielding sub-regions  1182 . Correspondingly, the light-transparent sub-region  1184  is in the form of rectangle, and the average light transmittance per unit area of the light modulation region  118  substantially maintains constant from the light-shielding region  113  to the light-transparent region  114  when the patterned layer  120  is not disposed in the light-transparent sub-regions  1184 . In other words, the width of the light-transparent sub-region  1184  substantially maintains constant from the light-shielding region  113  to the light-transparent region  114 , or the area ratio of the light-transparent sub-region  1184  to the light-shielding sub-region  1182  (i.e. ratio of light-transmitting area of the light modulation region  118 ) substantially maintains constant from the light-shielding region  113  to the light-transparent region  114 . When the patterned layer  120  is disposed, for example adjacent to the light-shielding region  113  (at the first end) in the light-transparent sub-regions  1184 , the light transmittance of the light modulation region  118  is further modulated (e.g. reduced), so as to achieve a desired light modulation. In other words, each of the plurality of light-shielding sub-regions  1182  has a substantially constant width, so a width of each of the plurality of light-transparent sub-regions  1184  and a width of the portion of the patterned layer  120  in each of the light-transparent sub-regions  1184  (i.e. the patterned sub-region  1201 ) are substantially constant from the light-shielding region  113  to the light-transparent region  114 . Moreover, in  FIG.  8 A , the vertical projection of the edge  132  of the light guide sheet  130  at least partially falls within the light modulation region  118 , and in  FIG.  8 B , the vertical projection of the edge  132  of the light guide sheet  130  falls within the light-shielding region  113  and adjacent to the light modulation region  118 . The distance (or relative position) between the edge  132  of the light guide sheet  130  and the light modulation region  118  as well as the position of the patterned layer  120  can be modified according to practical lighting effects to adopt a design similar to  FIG.  8 A  or  FIG.  8 B . 
     In the above embodiments, the light modulation region  118  is illustrated with the light-transparent sub-regions and the light-shielding sub-regions in the form of triangle or rectangle, but not limited thereto. In another embodiment (not shown), the light-transparent sub-regions and the light-shielding sub-regions may have any suitable shape, such as trapezoid, but not limited thereto. In other embodiments, according to practical applications, the light modulation region may have a gradation design by printing technology, so that the light transmittance of the light modulated region  118  is increased along the extending direction from the light-shielding region  113  through the patterned layer  120  toward the light-transparent region  114 . 
     As shown in  FIGS.  9 A and  9 B , the relative positions of the light modulation region  118  of the mask films  110  of  FIGS.  8 A and  7 A  and the light-transparent portion  222  of the keycap  220  are illustrated, respectively. In these embodiments, the light-transparent portion  222  of the keycap  220  are illustrated with the symbol of “Esc” as an example. The plurality of light-shielding sub-regions  1182  and the plurality of light-transparent sub-regions  1184  of the light modulation region  118  are alternatingly arranged along an extending direction (or disposing position) of the light-transparent portion  222 , and the plurality of patterned sub-regions  1201  is disposed at the top portion of the light-transparent sub-regions  1184 . In other words, the plurality of light-shielding sub-regions  1182  and the plurality of light-transparent sub-regions  1184  are preferably alternatingly arranged along the longitudinal direction of the light-transparent portion  222 . In an embodiment, the length of the light modulation region  118  extending from the light-shielding region  113  to the light-transparent region  114  and the width of the light modulation region  118  extending along the extending direction of the boundary line  115  are preferably at least equal to the height and the width of the light-transparent portion  222 . In other words, the light modulation region  118  preferably covers the entire light-transparent portion  222  in the length and width directions. The boundary line  115  is preferably connected to the light modulation region  118  at ½ of the height of the light-transparent portion  222 , but not limited thereto. 
       FIG.  10 A  is a schematic view of an eighth embodiment of the invention, which shows the relative position of the mask pattern  112  of the mask film  110 , the patterned layer  120 , and the light source  140 .  FIG.  10 B  is a variant embodiment of  FIG.  10 A . As shown in  FIGS.  10 A and  10 B , the light source  140  is disposed in the light source hole  134  of the light guide sheet  130 , and the mask film  110  is disposed on the light guide sheet  130  and covers the light source hole  134  (and the light source  140 ). When the light source  140  is disposed adjacent to the keyswitch  200 , the light modulation region  118  can be disposed at a location of the mask film  110  which corresponds to the keyswitch  200 , so as to modulate the lighting uniformity of the keyswitch  200 . For example, the mask pattern  112  (e.g. the light-shielding region  113 ) extends to cover the light source hole  134  (and the light source  140 ), and the light modulation region  118  can be disposed corresponding to the light-emitting surface  142  of the light source  140  and extend from the light-shielding region  113  to the light-transparent region  114 , i.e., the light modulation region  118  is located between the light-transparent region  114  and the light-emitting surface  142  of the light source  140 . The plurality of light-shielding sub-regions  1182  and the plurality of light-transparent sub-regions  1184  of the light modulation region  118  are alternatingly disposed along the light-emitting surface  142  of the light source  140 , and the plurality of patterned sub-regions  1201  is disposed adjacent to the light source  140  in the light-transparent sub-regions  1184 . In the embodiment of  FIG.  10 A , the light modulation region  118  has a configuration similar to  FIG.  7 A , wherein the width of the light-shielding sub-region  1182  is gradually reduced from the light-shielding region  113  to the light-transparent region  114 , and the average light transmittance per unit area of the light modulation region  118  is increased from the light-shielding region  113  to the light-transparent region  114 . In the embodiment of  FIG.  10 B , the light modulation region  118  has a configuration similar to  FIG.  8 A , wherein the width of the light-shielding sub-region  1182  substantially maintains the same from the light-shielding region  113  to the light-transparent region  114 , and the average light-transmitting rate per unit area of the light modulation region  118  substantially maintains the same from the mask pattern  112  to the light-transparent region  114  when the patterned layer  120  is not disposed in the light-transparent sub-regions  1184 . In practical applications, the number, shape, and size of the light-shielding sub-region  1182  (or the light-transparent sub-region  1184 ) of the light modulation region  118  as well as the patterned layer  120  can be modified according to the desired light intensity, the distance between the light-transparent region  114  and the light source  110 , the location of light-transparent portion  222  of the keycap  220 , and the like to achieve the desired optical effect. 
       FIG.  11 A  is a schematic view of the optical module in a ninth embodiment of the invention, showing the relative position of the mask pattern of the mask film, the patterned layer, and the light guide sheet. For heat dissipation and positioning purposes, the optical module generally has one or more through holes to allow air flow or positioning means (e.g. bolts or screws) to pass therethrough. As shown in  FIG.  6    and  FIG.  11 A , the mask film  110  has an upper hole  111 . The light guide sheet  130  has a hole  131 , and the reflective film  150  has a lower hole  151 . When the mask film  110 , the light guide sheet  130 , and the reflective film  150  are stacked on one another, the upper hole  111 , the hole  131 , and the lower hole  151  are aligned and communicate with each other to form the through hole. When the through hole is located adjacent to the keyswitch, the light modulation region  118  can be disposed at a position corresponding to the keyswitch. As shown in  FIG.  11 A , the hole  131  of the light guide sheet  130  has an edge  135 . The edge  117  of the upper hole  111  of the mask film  110  is located at the inner side of the edge  135  of the hole  131  of the light guide sheet  130 . In other words, the diameter of the upper hole  111  is smaller than that of the hole  131 , so that a portion of the mask film  110  around the upper hole  111  that protrudes into the hole  131  forms the light-shielding region  113  of a ring-like shape. The plurality of light-shielding sub-regions  1182  and the plurality of light-transparent sub-regions  1184  of the light modulation region  118  are alternatingly disposed along the edge  135  of the hole  131  of the light guide sheet  130 , and extend from the light-shielding region  113  to the light-transparent region  114 . Specifically, according to the actual location of the through hole corresponding to the keycap, the light modulation region  118  can fully surround the through hole to form a complete ring shaped region or partially surround the through hole to form a sector region. In this embodiment, the light modulation region  118  is illustrated to substantially completely surround the light-shielding region  113 , i.e., the through hole is substantially located completely in the light-transparent region  114  corresponding to the keycap, so that the light-transparent region  114  can be the peripheral region surrounding the light modulation region  118 , but not limited thereto. In another embodiment, the light modulation region  118  can be a sector region which partially surrounds the light-shielding region  113 , i.e., the through hole is partially located in the light-transparent region  114  corresponding to the keycap, so that the light-transparent region  114  can be the sector peripheral region surrounding the outer edge of the light modulation region  118 , and the light-shielding region  113  is connected to the lateral sides of the sector region and extends to the inner edge of the light modulation region  118 . 
     In this embodiment, each light-shielding sub-region  1182  has a triangle-like shape. The first end  1182   a  of the light-shielding sub-region  1182  is connected to the light-shielding region  113 , and the second end  1182   b  of the light-shielding sub-region  1182  extends to the light-transparent region  114 . The width of the first end  1182   a  is larger than that of the second end  1182   b , so that the width of the light-shielding sub-region  1182  is gradually reduced from the light-shielding region  113  to the light-transparent region  114 . In this embodiment, the central line of the second end  1182   b  of the light-shielding sub-region  1182  (e.g. angle bisector) preferably runs through the centers of the hole  131  and the upper hole  111 . The plurality of light-shielding sub-regions  1182  are preferably arranged along the edge  135  of the hole  131  of the light guide sheet  130 , so that one light-transparent sub-region  1184  is located between two adjacent light-shielding sub-regions  1182 . Correspondingly, the light-transparent sub-region  1184  has a triangle-like shape. Because the light modulation region  118  surrounds the light-shielding region  113  and extends radially outward toward the light-transparent region  114 , the wider bottom side of the light-transparent sub-region  1184  is proximate to the light-transparent region  114  and has an arc length larger than the arc length of the first end  1182   a  of the light-shielding sub-region  1182 , and the vertex of the light-transparent sub-region  1184  is proximate to the light-shielding region  113 . In this embodiment, when the mask film  110  and the light guide sheet  130  are stacked on each other, the vertical projection of the edge  135  of the hole  131  of the light guide sheet  130  on the mask film  110  at least partially falls within the light modulation region  118 , so that the lighting uniformity of the keyswitch which corresponds to the through hole can be enhanced by the light modulation region  118 . 
     In this embodiment, at least a portion of the patterned layer  120  is located in the light-transparent sub-regions  1184 . Each of the plurality of light-shielding sub-regions  1182  has a gradually reduced width, so a width of each of the plurality of light-transparent sub-regions  1184  and a width of the portion of the patterned layer  120  in each of the light-transparent sub-regions  1184  (i.e., the patterned sub-region  1201 ) are gradually increased from the light-shielding region  113  toward the light-transparent region  114 . With the arrangement of the patterned layer  120 , the light transmittance of the light modulation region  118  can be further modulated to improve the lighting uniformity of the keyswitch. 
       FIG.  11 B  is a variant embodiment of  FIG.  11 A . In this embodiment, the light-shielding sub-region  1182  has a sector shape, wherein the extending directions of two lateral sides of the sector preferably run through the centers of the hole  131  and the upper hole  111 . In this embodiment, because the light modulation region  118  surrounds the light-shielding region  113  and extends radially outward toward the light-transparent region  114 , the width of the first end  1182   a  of the light-shielding sub-region  1182  is smaller than that of the second end  1182   b , and the width of the light-shielding sub-region  1182  is gradually increased from the light-shielding region  113  to the light-transparent region  114 . In other words, the plurality of light-shielding sub-regions  1182  are arranged at intervals along the edge  135  of the hole  131  of the light guide sheet  130 , so that one light-transparent sub-region  1184  is located between two adjacent light-shielding sub-regions  1182 . Correspondingly, the light-transparent sub-region  1184  is in the form of sector, and the width of light-transparent sub-region  1184  is gradually increased from the light-shielding region  113  to the light-transparent region  114 . The area ratio of the light-transparent sub-region  1184  to the light-shielding sub-region  1182  of the light modulation region  118  substantially maintains the same from the light-shielding region  113  to the light-transparent region  114 , but the light-transmitting area of the light modulation region  118  is gradually increased as the distance from the light-shielding region  113  increases. In this embodiment, when the mask film  110  and the light guide sheet  130  are stacked on each other, the vertical projection of the edge  135  of the hole  131  of the light guide sheet  130  on the mask film  110  at least partially falls within the light modulation region  118 , so that the lighting uniformity of the keyswitch which corresponds to the through hole can be enhanced by the light modulation region  118 . 
     In this embodiment, at least a portion of the patterned layer  120  is located in the light-transparent sub-regions  1184 . Each of the plurality of light-shielding sub-regions  1182  has a gradually increased width, so a width of each of the plurality of light-transparent sub-regions  1184  and a width of the portion of the patterned layer  120  in each of the light-transparent sub-regions  1184  (i.e., the patterned sub-region  1201 ) are gradually increased from the light-shielding region  113  toward the light-transparent region  114 . 
     Moreover, in the above embodiments, the light-shielding sub-regions  1182  are illustrated to be formed by the same light-blocking material of the light-shielding region  113 , but not limited thereto. In other embodiments, the light-shielding sub-regions  1182  can be formed by the same light-blocking material of the patterned layer  120 . For example, in an embodiment, the patterned layer  120  constitutes the light-shielding sub-regions  1182  of the light modulation region  118 , and the portion of the light modulation region  118  without disposing the patterned layer  120  can be considered as the light-transparent sub-regions  1184 . In another embodiment, the patterned layer  120  can not only constitute the light-shielding sub-regions  1182  of the light modulation region  118 , but also partially or fully fill the light-transparent sub-regions  1184 . 
     It is noted that in other embodiments, one or more of the structure designs for enhancing the brightness or light distribution of the outer keyswitch of the above various embodiments (e.g. the design of non-linear light-exit edge and/or through hole of the light guide sheet, the design of auxiliary mask pattern and/or light-transparent sub-region of the mask film, the design of mask portion of the reflective film) can be optionally integrated into one or more keyswitches of a single luminous keyboard, so as to improve the lighting uniformity of the luminous keyboard. 
     It is noted that one or more arrangements of the light modulation region of the above various embodiments can be optionally integrated into a single luminous keyboard, so as to improve the lighting uniformity of the luminous keyboard by modulating the light distribution of the desired keyswitch(es), such as the outer keyswitch, the keyswitch adjacent to the through hole and/or the light source. Moreover, in the above embodiments, the patterned layer can be disposed at any suitable location to modulate the light transmittance, so as to achieve a desired light distribution. 
     Although the preferred embodiments of the invention have been described herein, the above description is merely illustrative. The preferred embodiments disclosed will not limit the scope of the invention. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.