Abstract:
An input device includes a plurality of manipulation portions; an input function portion manipulated by the manipulation portions to perform an input function; a light guiding sheet facing the rear side of the plurality of manipulation portions; and a light source applying light into the light guiding sheet, wherein a rear surface opposite to a front surface of the light guiding sheet facing the manipulation portions is provided with a plurality of concave portions which is depressed to the inside of the light guiding sheet, wherein each concave portion has a circular opening and an inner surface which is a smooth concave curve surface, and wherein light propagated through the inside of the light guiding sheet is reflected by the inner surface toward the inside of the light guiding sheet, and the light is applied from the front surface of the light guiding sheet to the manipulation portions.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present invention claims the benefit of the following: Japanese Patent Application JP 2008-267178 filed in the Japanese Patent Office on Oct. 16, 2008; Japanese Patent Application JP 2009-067287 filed in the Japanese Patent Office on Mar. 19, 2009; and Japanese Patent Application JP 2009-067289 filed in the Japanese Patent Office on Mar. 19, 2009. The entire contents of each application is incorporated herein by reference. 
     BACKGROUND OF THE DISCLOSURE 
     1. Technical Field 
     The present invention relates to an input device which has an illumination function and a keyboard device in which contacts contact with each other by a plurality of key tops, and particularly, to a keyboard device having a function of illuminating a key top. 
     2. Related Art 
     Personal computers or various information searching apparatuses are equipped with a keyboard device in which a plurality of key tops are arranged. 
     In recent years, the keyboard device has been required to have an illumination function of allowing a user to recognize key tops in a dark place. Particularly, book-type or laptop-type personal computers have been required to be equipped with an input device and a keyboard device having an illumination function so as to visually recognize the key tops in a dark place. 
     In a keyboard device disclosed in Japanese Patent Application Laid-open No. 2002-251937, an electroluminescent element is disposed on the rear side of a base substrate supporting key tops, and light emitted from the electroluminescent element is applied to the key tops through perforation holes formed in the base substrate. 
     In a keyboard device disclosed in Japanese Registered Utility Model No. 3082585, a plate-shaped light emitting element including a cold-light plate or a cold-cathode plate is formed on a base, a circuit board and an elastic sheet are laminated on the light emitting element, and then a plurality of key tops is formed on the elastic sheet. Light emitted from the plate-shaped light emitting element is applied to the key tops through holes formed in the circuit board and the elastic sheet. 
     In the keyboard device disclosed in Japanese Patent Application Laid-open No. 2002-251937, the electroluminescent element is disposed on the rear side of the base substrate, and the light is applied to the key tops through the perforation holes opened to the base substrate. Further, in the keyboard device disclosed in Japanese Registered Utility Model No. 3082585, the light emitted from the plate-shape light emitting element is applied to the key tops through the holes formed in the circuit board and the elastic sheet. 
     Likewise, since the known keyboard devices have a structure in which the light emitted from the light source is applied to the key tops through the holes formed in other members located above the light source, the utilization efficiency of the light used for illuminating the key tops is not satisfactory. In addition, since the light is interrupted by the base substrate or the like interposed between the key top and the light source, it is difficult to uniformly illuminate the key tops. 
     Further, in the keyboard devices disclosed in Japanese Patent Application Laid-open No. 2002-251937 and Japanese Registered Utility Model No. 3082585, since the sheet-shaped light source is used, it is not possible to intensively apply the light to an illumination target position of the key top. 
     These and other drawbacks exist. 
     SUMMARY OF THE DISCLOSURE 
     The present invention solves the above-described problems, and an object of the invention is to provide an input device and a keyboard device having an illumination function capable of efficiently applying light emitted from a light source to a key top and clearly illuminating an illumination target position of the key top. 
     According to an exemplary embodiment, there is provided an input device including: a plurality of manipulation portions; an input function portion which is manipulated by the manipulation portions to perform an input function; a light guiding sheet which faces the rear side of the plurality of manipulation portions; and a light source which applies light to the inside of the light guiding sheet, wherein a rear surface opposite to a front surface of the light guiding sheet facing the manipulation portions is provided with a plurality of concave portions which is depressed to the inside of the light guiding sheet, wherein each concave portion has a circular opening and an inner surface which is a smooth concave curve surface, and wherein light propagated through the inside of the light guiding sheet is reflected by the inner surface toward the inside of the light guiding sheet, and the light is applied from the front surface of the light guiding sheet to the manipulation portions. 
     In an input device according to this embodiment, since the light is guided by the light guiding sheet disposed on the rear side of the manipulation portions so as to illuminate each of the manipulation portions, it is possible to decrease the number of light sources, and thus to manufacture the input device at a low cost. In addition, since the light emitting element is not disposed on the rear side of the manipulation portions, even when the manipulation portions are frequently manipulated by strong force, the durability of the light emitting function does not deteriorate. 
     In addition, since the rear surface of the light guiding sheet is provided with the concave portions each having the inner surface which is the concave curve surface, and the light propagated through the inside of the light guiding sheet is reflected by the inner surface as the curve surface to the inside of the light guiding sheet so as to be applied from the front surface of the light guiding sheet to the manipulation portions, it is possible to intensively apply the light to the illumination target position of the manipulation portion. Further, since the inner surface of the concave portion is the smooth surface, a diffused reflection of the light propagated through the inside of the light guiding sheet does not occur in the inner surface, thereby easily preventing the attenuation of the light. For this reason, it is possible to apply the light having high illuminance to the manipulation portion located at a position distant from the light source. 
     According to an exemplary embodiment, there is provided a keyboard device including: a chassis; a plurality of key tops; and support members which are formed on the chassis and support the key tops so as to be movable in the vertical direction, wherein a lower contact, a flexible pressing sheet covering the lower contact, and a contact input portion formed on a lower surface of the pressing sheet and having an upper contact facing the lower contact are disposed between the chassis and each key top, wherein a plurality of the contact input portions is disposed at positions pressed by the key tops, wherein the pressing sheet or a coating sheet laminated on the pressing sheet is a light guiding sheet which propagates light therein, wherein a light source is disposed on the chassis so as to apply light to the inside of the light guiding sheet, wherein a rear surface opposite to a front surface of the light guiding sheet facing the key tops is provided with a plurality of concave portions, and wherein light propagated through the inside of the light guiding sheet is reflected by the concave portions toward the key tops. 
     In a keyboard device according to this embodiment, the pressing sheet forming the contact input portions or a coating sheet laminated thereon is the light guiding sheet, and a wide portion of the front surface of the light guiding sheet faces the key tops. For this reason, most of the light emitted from the front surface of the light guiding sheet is not interrupted and is applied to the key tops, thereby efficiently illuminating the key tops. 
     In addition, since the light guiding sheet is disposed at the uppermost portion of the contact input portion, it is not necessary to form the sheet, the contact, or the like located below the light guiding sheet to be transparent. Since it is not necessary to form a portion below the light guiding sheet to be transparent, it is possible to decrease a cost of a material. 
     Further, since the rear surface of the light guiding sheet is provided with the concave portions, and the light propagated through the inside of the light guiding sheet is reflected by the inner surfaces of the concave portions so as to be applied from the front surface of the light guiding sheet to the key tops, it is possible to intensively apply the light to an illumination target position of the key top. 
     For example, in a keyboard device according to this embodiment, the lower contact may be formed on a front surface of a substrate sheet, the substrate sheet may be fixed to the pressing sheet with an adhesive layer interposed therebetween except for a region where the lower contact faces the upper contact. The adhesive layer may be formed to have a thickness which allows the lower and upper contacts to face each other with a gap interposed therebetween. 
     In the above-described structure, since it is possible to form the contact input portion to be thin, it is possible to realize the thin keyboard device. 
     Each concave portion according to this embodiment has a circular, oval, or elliptical opening and an inner surface which is a smooth concave curve surface. 
     Since the inner surface of the concave portion formed in the light guiding sheet is the smooth surface, a diffused reflection of the light propagated through the inside of the light guiding sheet does not occur in the inner surface, and the light is reflected toward the key top in the state where the directivity of the light is maintained. For this reason, it is possible to easily prevent the attenuation of the light and to apply the light having high illuminance to the key top located at a position distant from the light source. 
     It is also possible to prevent a difference in illumination luminance in accordance with a distance from the light source by appropriately changing the size or shape of the concave portion. 
     For example, a depth of the concave portion and an inclined angle of the inner surface with respect to the rear surface are set to be different depending on a location of the light guiding sheet. In this case, the depth and the angle may increase in a direction away from the light source. 
     Further, the concave portions having different depths and angles may exist in a region where light is applied to the same key top. 
     By using the concave portions having different depths and angles, it is possible to optimally illuminate the illumination target position of the key top in accordance with the location, shape, and width of the illumination target position. 
     Further, an area of the opening of the concave portion may be different depending on a location of the light guiding sheet. 
     Furthermore, arrangement density of the plurality of concave portions may be different depending on a location of the light guiding sheet. In this case, the arrangement density of the concave portions facing the key top distant from the light source may be higher than that of the concave portions facing the key top adjacent to the light source. 
     In this embodiment, the concave portion formed in the light guiding sheet is formed by decomposing a part of a synthetic resin material, forming the light guiding sheet, using energy of a laser. 
     In a keyboard device according to this embodiment, the light source may be disposed between the adjacent support members supporting the key tops, and the light guiding sheet may be provided with a hole for allowing the light source to be inserted therein. 
     Since the light source is disposed between the adjacent support members, it is possible to decrease a distance from the light source to each key top, and thus to improve the utilization efficiency of the light. 
     According to various embodiments, there is provided a keyboard device including: a chassis; a plurality of key tops; support members which are formed on the chassis and support the key tops so as to be movable in the vertical direction; contact input portions which receive pressing force from the key tops so that facing contacts contact with each other; a light source; a light guiding sheet which applies light emitted from the light source to the key tops; and a mask member which is formed above the chassis and below the key tops so as to cover a gap between the adjacent key tops from the chassis. 
     In a keyboard device according to these embodiments, since the mask member is disposed between the chassis and the key tops, it is possible to easily prevent the light from leaking between the adjacent key tops. 
     In a keyboard device according to these embodiments, the mask member may include a shielding portion in which a shielding film is formed on a flexible and translucent base sheet and a translucent portion in which the shielding film is not formed. The shielding portion may be disposed at a position covering the gap between the adjacent key tops from the downside of the gap. The contact input portions may be covered by the base sheet, and the pressing force of the key tops may be applied to the contact input portions through the base sheet. 
     As described above, if the mask member is formed by the flexible sheet, even when a notch is not formed in a position pressing the contact input portion, the base sheet is deformed by the pressing force applied from the key top, and hence the contact input portion is pressed. Accordingly, it is not necessary to form a plurality of window portions, used to press the contact input portion, by cutting, and thus to easily handle the mask member. 
     In this embodiments, the translucent portion of the mask member may be formed at a position facing the lower side of each of the plurality of key tops, and an edge of the translucent portion may be located on the inside of an edge of each key top. 
     Since the area of the translucent portion formed in the mask member is set to be smaller than that of the key top, it is difficult for the light passing through the translucent portion to be diffused to the gap between the adjacent key tops. 
     Also, the light guiding sheet may be disposed above the chassis and below the mask member, and a portion of the light guiding sheet facing the translucent portion may be provided with a reflection region which reflects light toward the key tops. 
     Since the light guiding sheet is disposed above the chassis, the light reflected by the reflection region of the light guiding sheet is not shielded by the chassis or the like, and the light is applied to the key tops. Accordingly, it is possible to improve the utilization efficiency of the light. In addition, since the light guiding sheet is covered by the mask member, the light hardly leaks to the gap between the adjacent key tops. 
     According to an exemplary embodiment, it is possible to realize the input device having the illumination function and formed to have a thin frame by disposing the thin light guiding sheet on the rear side of the plurality of input portions. In addition, since it is not necessary to provide alight emitting element facing each manipulation portion, it is possible to decrease the cost. Also, even when the manipulation portion is frequently manipulated, the durability of the illumination function does not deteriorate. 
     Further, it is possible to intensively apply the light to the illumination target position of the manipulation portion. Also, since the manipulation portion is hardly influenced by a variation in the distance from the light source, it is possible to decrease a difference in brightness of the illuminated manipulation portions. In addition, since the attenuation of the light hardly occurs due to the diffused reflection of the light propagated through the inside of the light guiding sheet, it is possible to apply the light having high illuminance from the light source to the manipulation portions. 
     Furthermore, according to an exemplary embodiments, it is possible to improve the utilization efficiency of the light used to illuminate the key tops of the keyboard device. In addition, it is possible to intensively apply the light to the illumination target position of the key top. Also, since the key top is hardly influenced by a variation in the distance from the light source, it is possible to decrease a difference in brightness of the illuminated key tops. In addition, since the attenuation of the light hardly occurs due to the diffused reflection of the light propagated through the inside of the light guiding sheet, it is possible to apply the light having high illuminance from the light source to the key tops. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial plan view showing a part of a keyboard device according to a embodiment of the disclosure. 
         FIG. 2  is a partial plan view showing a state where key tops are removed from the keyboard device shown in  FIG. 1 . 
         FIG. 3  is a sectional view showing the keyboard device and corresponding to a section taken along the line III-III in  FIG. 2 . 
         FIG. 4  is an enlarged view illustrating a structure of an illumination function portion. 
         FIG. 5  is an enlarged view illustrating a structure of the illumination function portion according to an embodiment of the disclosure. 
         FIGS. 6A ,  6 B, and  6 C are diagrammatic views showing an actual measurement value of a shape of a concave portion formed in a light guiding sheet. 
         FIG. 7  is a sectional view showing the input device according to an embodiment of the disclosure. 
         FIG. 8  is an enlarged view showing a structure of the illumination function portion in  FIG. 7 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following description is intended to convey a thorough understanding of the embodiments described by providing a number of specific embodiments and details involving input and keyboard devices having illumination portions. It should be appreciated, however, that the present invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art, in light of known systems and methods, would appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments, depending on specific design and other needs. A keyboard device  1  according to a first embodiment shown in  FIGS. 1 to 4  is mounted to a book-type, laptop-type, or desktop-type personal computer. 
     The keyboard device  1  may include a metallic chassis  2 , where plural key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e  may be arranged on the chassis  2  in the longitudinal direction and the transverse direction. As shown in  FIG. 1 , the key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e  may be separated according to sizes of key tops  15  respectively formed in the key input portions. In addition, in the following description, the key tops having different sizes are denoted by the same reference numeral  15 . 
       FIG. 3  is a sectional view showing a section of the keyboard device  1  taken along the line III-III in  FIG. 2 , where the key input portions  10   c  and  10   d  are shown. The lengths of the other key input portions  10   a ,  10   b , and  10   e  may be different from the lengths of the key input portions  10   c  and  10   d  in the transverse direction in the key top  15 , but the other structures may be substantially the same as those of the key input portions  10   c  and  10   d.    
     As shown in  FIG. 3 , a membrane lamination body  20  and a mask sheet  30  may be sequentially laminated on the chassis  2  in an overlapping manner, and the key top  15  may be formed at an upper position distant from the chassis  2 . In addition, in  FIG. 4 , the chassis  2 , the membrane lamination body  20 , and the mask sheet  30  are depicted so as to be distant from each other in the vertical direction, but in fact, a substrate sheet  21  of the membrane lamination body  20  may be adhered and fixed onto the chassis  2  and the mask sheet  30  may be adhered and fixed to a pressing sheet  22 . 
     In the portions provided with the key input portions  10   c  and  10   d , a first support piece  11   a  and a second support piece  11   b  of the chassis  2  may be bent upward. In the portions provided with the key input portions  10   c  and  10   d , a pair of the first support pieces  11   a  may be formed so as to be distant from each other in a direction perpendicular to a paper sheet of  FIG. 3 , and a pair of the second support pieces  11   b  may be formed so as to be distant from each other in a direction perpendicular to the paper sheet. A hole  20   a  may be opened to the membrane lamination body  20 , and a hole  30   a  may be opened to the mask sheet  30  so as to be connected to the hole  20   a  in the vertical direction. The first and second support pieces  11   a  and  11   b  may protrude from the membrane lamination body  20  through the holes  20   a  and  30   a.    
     A first movable support member  16  and a second movable support member  17  may be formed between each key top  15  and the chassis  2 . In the first movable support member  16 , one end  16   a  may be supported to the first support piece  11   a  so as to be rotatable, and the other end  16   b  may be supported to the lower portion of the key top  15  so as to be rotatable and slidable in the transverse direction. In the second movable support member  17 , one end  17   a  may be supported to the lower portion of the key top  15  so as to be rotatable, and the other end  17   b  may be supported to the second support piece  11   b  so as to be rotatable and slidable in the transverse direction. The center portions of the first movable support member  16  and the second movable support member  17  may be connected to each other so as to be rotatable, and hence the first movable support member  16  and the second movable support member  17  may constitute an X-shaped support link. In this embodiment, the X-shaped support link may be a support member which may support the key top  15  so as to be elevatable. 
     An elastic member  18  may be formed between the mask sheet  30  and the key top  15 . The elastic member  18  may be formed of synthetic rubber, and may be an urging member which applies upward urging force to the key top  15  in a direction moving away from the chassis  2 . The inside of the lower portion of the elastic member  18  may be a cavity, and a downward pressing convex portion  18   a  may be integrally formed with the cavity. 
     As shown in an enlarged view in  FIG. 4 , the membrane lamination body  20  may be formed by laminating a substrate sheet  21 , a pressing sheet  22 , and a spacer layer  23  interposed between both sheets  21  and  22 . A portion facing the pressing convex portion  18   a  of the elastic body  18  may be provided with a contact input portion  24  without the spacer layer  23 . The contact input portion  24  may be formed in a position facing the pressing convex portion  18   a  of the elastic member  18  formed in each of the key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e.    
     As shown in  FIG. 4 , in the contact input portion  24 , a pair of lower contacts  25   a  and  25   a  may be formed in a surface of the substrate sheet  21 , and an upper contact  26  may be formed in a lower surface of the pressing sheet  22  so as to face the lower contacts  25   a  and  25   a . Each of the lower contacts  25   a  and  25   a  may be electrically connected to a conductive pattern wired in the surface of the substrate sheet  21 . In the key input portions  10   c ,  10   d , and the like, when the key top  15  is pressed, one end  16   a  of the first movable support member  16  may be rotated about an engagement portion engaging with the first support piece  11   a  and serving as a support point, and one end  17   a  of the second movable support member  17  may be rotated at the lower portion of the key top  15  so as to move down the key top  15 . At this time, the elastic member  18  may be pressed down by the key top  15 , and the pressing sheet  22  of the contact input portion  24  may be pressed through the pressing convex portion  18   a  and the mask sheet  30 . The upper contact  26  contacts with the pair of lower contacts  25   a  and  25   a  so that the lower contacts  25   a  and  25   a  may be electrically connected to each other. In this manner, a key input signal may be obtained. 
     The spacer layer  23  interposed between the substrate sheet  21  and the pressing sheet  22  in a region excluding the contact input portion  24  may be an adhesive layer. The spacer layer  23  may include an organic resin layer  23   a  which may be formed on the surface of the substrate sheet  21  and may be formed of a resist material or the like and an adhesive layer  23   b  which is laminated thereon. The organic resin layer  23   a  may be formed in the surface of the substrate sheet  21  by means of a screen printing process or the like in a region excluding the contact input portion  24 . The adhesive layer  23   b  may be formed in a surface of the organic resin layer  23   a  in a region excluding the contact input portion  24  by means of a screen printing process or the like, and the pressing sheet  22  may be fixed by the adhesive layer  23   b.    
     Since the spacer layer  23  may be formed as the adhesive layer, the membrane lamination body  20  may be formed to be thin. In addition, since the spacer layer  23  may be formed as a lamination body of the organic resin layer  23   a  and the adhesive layer  23   b , it is possible to maintain a wide gap between the substrate sheet  21  and the pressing sheet  22  in the vertical direction. Accordingly, in the contact input portion  24 , it is possible to maintain a vertical gap between the lower contacts  25   a  and  25   a  and the upper contact  26 . 
     In the keyboard device  1  shown in  FIGS. 3 and 4 , the pressing sheet  22  as the uppermost layer of the membrane lamination body  20  may serve as a light guiding sheet. 
     As shown in  FIG. 4 , a hole  20   b  may be opened to the membrane lamination body  20  so as to penetrate in the vertical direction. A light emitting diode device  29  as a light source may be fixed to a surface of the chassis  2  through a flexible interconnection substrate or the like, and the light emitting diode device  29  is inserted into the hole  20   b . The light emitting diode device  29  may be formed by accommodating a bare tip of the light emitting diode in a transparent package, and may be capable of emitting light in all directions to the vicinity thereof. Since the light emitting diode device  29  faces an end surface  22   a  of the pressing sheet  22  as the light guiding sheet inside the hole  20   b , the light emitted from the light emitting diode device  29  may be guided from the end surface  22   a  to the inside of the pressing sheet  22 . 
     The thickness of the pressing sheet  22  may be less than 1 mm, and may be less than 500 μm. In this embodiment, the thickness of the pressing sheet  22  may be approximately 300 μm. 
     In the pressing sheet  22 , a front surface  22   c  facing the key top  15  and a rear surface  22   d  facing the chassis  2  may be formed as a flat surface as a smooth mirror surface. In the pressing sheet  22 , a reflection region  27  having a predetermined area may be separately set, and the reflection region  27  may be provided with plural concave portions  28 . 
     Each concave portion  28  may be formed in such a manner that energy such as a CO 2  laser may be applied to an extremely small area of the rear surface  22   d  of the pressing sheet  22  so as to decompose and remove a part of a material forming the pressing sheet  22 . For this reason, the pressing sheet  22  may be formed of a material which may be transparent and may be decomposed by energy of the laser. As a transparent film material which is thin and flexible, has comparatively high strength, and is decomposed by energy of the laser, for example, polycarbonate, urethane, silicon, or the like may be used. 
     Since the concave portion  28  may be formed in such a manner that energy of a minute spot laser may be applied to the rear surface  22   d  of the pressing sheet  22  so as to decompose and remove a part of the material forming the pressing sheet  22 , a shape of an opening of the concave portion  28  when seen from the rear surface  22   d  may be a circular shape. The circular shape may be a round shape or an oval shape. In addition, an opening area of the concave portion  28  may become gradually small toward the bottom portion of the concave portion  28 , and the entire inner surface of the concave portion  28  may be formed in a concave curve surface shape. Further, since the concave portion  28  may be formed by decomposing the material forming the pressing sheet, the inner surface of the concave portion  28  may be formed as a smooth surface, that is, a mirror surface throughout the entire area thereof. Herein, the smooth surface or the mirror surface may indicate that the surface roughness is substantially equal to the surface roughness of the front surface  22   c  and the rear surface  22   d  or the surface roughness is smaller than those of the front surface  22   c  and the rear surface  22   d . Further, the smooth surface or the mirror surface may indicate such a characteristic that a diffused reflection of the light does not occur in the inner surface of the concave portion  28  and the light is reflected on the basis of the principle of the incident angle and the reflection angle inside the sheet in accordance with the angle of the inner surface when the light propagated through the inside the pressing sheet  22  contacts with the inner surface of the concave portion  28  from the inside of the sheet. 
     As shown in  FIG. 4 , light L emitted from the light emitting diode device  29  so as to be incident from the end surface  22   a  into the pressing sheet  22  may be propagated through the inside of the pressing sheet  22  by repeating the reflection in the front surface  22   c  and the reflection in the rear surface  22   d . When the light propagated through the inside of the pressing sheet  22  contacts with the inner surface of the concave portion  28 , the light may be reflected toward the inside of the pressing sheet  22  so that the incident angle and the reflection angle are substantially equal to each other with respect to an imaginary plane contacting with the inner surface of the concave portion  28  at the light contact position, and the light is directed to the front surface  22   c . Then, the key top  15  may be illuminated by the light La emitted from the front surface  22   c  of the pressing sheet  22 . 
     The membrane lamination body  20  may be formed in a wide area extending throughout the entire area of the keyboard device  1 , and may include the reflection region  27  and the contact input portion  24  facing the lower portions of the key tops  15  of all the key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e . For example, as shown in  FIG. 2 , the hole  20   b , into which the light emitting diode device  29  is inserted, is formed at a position depicted by “i” between a third key input portion and a fourth key input portion from the bottom in  FIG. 2 . The hole  20   b  may be formed at a position between the adjacent key input portions and between the adjacent X-shaped links each including the first and second movable support members  16  and  17 . The light emitting diode device  29  capable of emitting light in all directions in the vicinity thereof may be disposed inside the hole  20   b.    
     For this reason, it may be possible to prevent the light emitting diode device  29  from being extremely distant from each reflection region  27  of all the key input portions, and thus to efficiently and uniformly apply the light of the light emitting diode device  29  to the reflection regions  27  formed in the key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e.    
     Alternatively, the light emitting diode device  29  may be disposed at a position depicted by “ii” in  FIG. 2 , and the light emitted from the light emitting diode device  29  may be incident from the lower edge of the pressing sheet  22  in  FIG. 2  to the inside of the pressing sheet  22 . Alternatively, the light emitting diode device  29  may be disposed so as to face the left and right edges of the pressing sheet  22 . 
     The mask sheet  30  may include a translucent and flexible base sheet  31  such as PET (polyethylene-terephthalate). Herein, the translucency may indicate such a characteristic that the light La emitted from the front surface  22   c  of the pressing sheet  22  may be propagated so as to illuminate the key top  15 . 
     The mask sheet  30  may include a shielding portion  32  and a translucent portion  33 . The shielding portion  32  may have a shielding film which may be formed on the surface of the base sheet  31  so as not to propagate the light therethrough. The shielding film may be a black or dark green layer, and may be formed by printing a resin layer on the surface of the base sheet  31  or by sputtering an inorganic layer such as a metal layer. The translucent portion  33  does not have a shielding film and hence can propagate light therethrough. 
     In  FIG. 2 , the shielding portion  32  of the mask sheet  30  may be depicted by hatching, and the translucent portion  33  may not be depicted by hatching. Each translucent portion  33  may be formed in a square shape. 
     Regarding the plan view shown in  FIG. 2 , the edge of the translucent portion  33  may be located on the inside of the edge of the key top  15  and an area of the translucent portion  33  may be smaller than that of the key top  15  so that the translucent portion  33  does not protrude from the edge of each key top  15  formed in all the key input portions  10   a ,  10   b ,  10   c ,  10   d , and  10   e . As a result, the shielding portion  32  may be located below a gap between the adjacent key tops  15 . 
     As shown in  FIG. 2 , the hole  20   b  formed in the membrane lamination body  20  may be covered by the shielding portion  32  of the mask sheet  30 , and the upper portion of the light emitting diode device  29  disposed inside the hole  20   b  may be covered by the shielding portion  32 . 
     Accordingly, even when the light emitting diode device  29  is disposed below the gap between the adjacent key tops  15 , the light emitted upward from the light emitting diode device  29  may be shielded by the shielding portion  32  so as to prevent the light from leaking from the gap between the adjacent key tops  15 . In addition, it may be possible to prevent the light propagated through the inside of the pressing sheet  22  from leaking upward from the gap between the adjacent key tops  15 . However, as shown in  FIG. 4 , since the reflection region  27  having the plural concave portions  28  is formed on the lower side of the translucent portion  33 , the light La propagated through the inside of the pressing sheet  22  and reflected by the concave portion  28  of the reflection region  27  may be applied to the key top  15  through the translucent portion  33 . 
     As shown in  FIG. 4 , a body portion  15   a  of the key top  15  may be formed of a semitransparent translucent material or a transparent material such as polycarbonate, and a surface of the body portion  15   a  may be provided with a coating layer  15   b  which may be formed by coating or nonelectrolytic plating so as not to allow light to pass therethrough. An illumination display portion  15   c  may be formed by removing a part of the coating layer  15   b  using a CO 2  laser or the like. In the keyboard device  1  shown in  FIG. 1 , the illumination display portion  15   c  formed on the surface of the key tops  15  may correspond to a display showing a character, a sign, or a number. 
     In  FIG. 1 , the reflection region  27  having the plural concave portions  28  is shown as a region depicted by the dashed line. The reflection region  27  may be located right below the illumination display portion  15   c  formed in each key top  15  so as to be formed in an area slightly wider than that of the illumination display portion  15   c . That is, in the plan view shown in  FIG. 1 , the illumination display portion  15   c  formed in each key top  15  is formed in a range of the reflection region  27 . 
     In the keyboard device  1  shown in  FIGS. 1 to 4 , the pressing sheet  22  as the uppermost layer of the membrane lamination body  20  may be used as the light guiding sheet. The light emitted from the light emitting diode device  29  may be propagated through the inside of the pressing sheet  22 , may be reflected by the plural concave portions  28  formed in the reflection region  27 , and then may be applied to the illumination display portion  15   c  of the key top  15  through the translucent portion  33  of the mask sheet  30 . Since the translucent portion  33  of the mask sheet faces the upper portion of the pressing sheet  22  instead of disposing a metallic substrate or a resinous circuit board thereon, the light La reflected upward from the reflection region  27  may be efficiently applied to the illumination display portion  15   c  so as to clearly illuminate the illumination display portions  15   c  of all the key tops  15 . 
     In addition, since the substrate sheet  21 , the lower contacts  25   a  and  25   a , or the upper contact  26  can be formed of a non-translucent material, it may be possible to reduce a cost of a material forming the constituent. 
     As shown in  FIG. 2 , since the hole  20   b  formed in the membrane lamination body  20  may be disposed between the key input portions and the light emitting diode device  29  is disposed inside the hole  20   b , it may be possible to prevent the light emitting diode device  29  from being excessively distant from the reflection region  27  formed in each key input portion. Accordingly, it may be possible to reduce the luminance defect of the illumination display portions  15   c  of the key tops  15  located in all the key input portions. 
     As shown in  FIG. 3 , the first and second movable support members  16  and  17  and the elastic body  18  may be interposed in the light path in which the light La reflected by the concave portion  28  of the reflection region  27  is directed to the illumination display portion  15   c . Accordingly, the first and second movable support member  16  and  17  and the elastic body  18  may be formed of a transparent or semitransparent translucent material. Also, the first and second movable support members  16  and  17  and the elastic member  18  may be formed of a white synthetic resin material or the like so as to reflect or diffuse the light from the surfaces thereof. In this case, the light reflected by the reflection region  27  may be reflected or diffused by the first and second movable support members  16  and  17  or the elastic member  18 , and may be applied to the key top  15 . 
       FIGS. 6A ,  6 B, and  6 C show actual results obtained by measuring the surface shape of the concave portion  28  using a laser microscope, where the concave portion  28  is actually formed by irradiating a CO 2  laser to the rear surface  22   d  of the pressing sheet  22  formed of polycarbonate.  FIGS. 6A ,  6 B, and  6 C are diagrammatic views showing the sectional shape in a surface perpendicular to the rear surface  22   d  based on the center of the concave portion  28 . 
     As shown in  FIGS. 6A ,  6 B, and  6 C, when the energy of the irradiation period of the CO 2  laser applied to the rear surface  22   d  is changed, it is possible to freely set an opening area φ of the opening  28   a  of the concave portion  28  or a depth D from the rear surface  22   d  to a bottom portion  28   b  of the concave portion  28 . The period during which the CO 2  laser is applied is the longest in  FIG. 6A . The period during which the CO 2  laser is applied is the shortest in  FIG. 6C . The period during which the CO 2  laser is applied falls in the range thereof in  FIG. 6B . Accordingly, the opening area φ of the opening  28   a  is the largest in  FIG. 6A  and is the smallest in  FIG. 6C . In addition, the depth D is the deepest in  FIG. 6A  and is the shallowest in  FIG. 6C . 
     From the diagrammatic views shown in  FIGS. 6A ,  6 B, and  6 C, it is understood that the inner surface  28   c  of the concave portion  28  is a concave curve surface smoothly continuous from the opening  28   a  to the bottom portion  28   b  and the bottom portion  28   b  is a smooth concave curve surface. An inclined angle θ of the inner surface  28   c  of the concave portion  28  with respect to the rear surface  22   d  is the largest in  FIG. 6A  and is the smallest in  FIG. 6C . 
     A hole diameter of the opening  28   a  of the concave portion  28  is not more than approximately 500 μm, and may not be more than approximately 300 μm. The depth D of the concave portion  28  is not less than approximately 5 μm, and may not be more than approximately ⅓ of a plate thickness of the pressing sheet  22 . 
     As shown in  FIG. 4 , when the light L propagated through the inside of the pressing sheet  22  is located at the inner surface  28   c  of the concave portion  28  inside the sheet, the light is mainly reflected toward the front surface  22   c . As shown in  FIG. 6A , as the depth D of the concave portion  28  is large and the inclined angle θ of the inner surface  28   c  is large, it may be possible to increase an ability of directing the light upward in the perpendicular direction. In addition, as the depth D of the concave portion  28  is large and the inclined angle θ of the inner surface  28   c  is large, it may be possible to increase the sum of the intensity of the light reflected by the inner surface  28   c  of one concave portion  28 . 
     Accordingly, when the opening area or the depth D of the concave portion  28  inside the same pressing sheet  22  is differently set in accordance with the distance from the reflection region  27  to the light emitting diode device  29  as the light source, the width of the reflection region  27 , or the size of the illumination display portion  15   c , it is possible to reduce a difference between the reflected light intensities due to a difference in the distance from the light emitting diode device  29  to the reflection region  27 . 
     In the arrangement of the concave portions  28 , the depth D of the concave portion  28  formed in the reflection region  27  distant from the light emitting diode device  29  is set to be larger than that of the reflection region  27  adjacent to the light emitting diode device  29 . As a result, the angle θ may be set to be large. In addition, even in the same reflection region  27 , the depth D and the angle θ may become gradually large in a direction moving away from the light emitting diode device  29 . 
     In addition, the arrangement density of the concave portions  28  formed in the reflection region  27  distant from the light emitting diode device  29  may be set to be higher than that of the reflection region  27  adjacent to the light emitting diode device  29 . Further, even in the same reflection region  27 , the arrangement density may be set to be high in a direction moving away from the light emitting diode device  29 . 
     Furthermore, when the concave portions having different depths D and opening areas φ exist in the same reflection region  27 , it may be possible to focus the light to the illumination display portion  15   c  or to apply light having light intensity in accordance with the size or the like of the character of the illumination display portion  15   c  to the illumination display portion  15   c.    
     Since the concave portion  28  may be formed by irradiating a laser to the rear surface  22   d  of the pressing sheet  22 , it may be possible to freely design and arrange plural types of concave portions  28  in the same pressing sheet  22  by changing the laser irradiation period or the irradiation energy. 
       FIG. 5  is a sectional view showing a keyboard device  101  according to various embodiments of the invention and corresponding to the sectional view in  FIG. 4 . 
     In the keyboard device  101  shown in  FIG. 5 , the same reference numerals are given to the same constituents as those of the keyboard device  1  according to the first embodiment. 
     In the keyboard device  101  shown in  FIG. 5 , a membrane lamination body  120  may include the substrate sheet  21 , the pressing sheet  22 , and the spacer layer  23 , where the contact input portion  24  may be formed in a portion without the spacer layer  23 . However, the concave portions  28  may not be formed in the pressing sheet  22 , and the pressing sheet  22  may be formed of a PET sheet of which both surfaces are smooth. 
     A coating sheet  40  may be formed between the pressing sheet  22  of the membrane lamination body  120  and the base sheet  31  of the mask sheet  30 , and the coating sheet  40  may be adhered to the pressing sheet  22  and the base sheet  31 . In addition, the coating sheet  40  may serve as a light guiding sheet. 
     The coating sheet  40  may be formed of a material such as polycarbonate which is easily decomposed by a laser. In addition, plural concave portions  28  may be formed in a rear surface  40   b  of the coating sheet  40  so as to face the reflection region  27 . The concave portions  28  may be formed by decomposing a part of the material, forming the coating sheet, using a laser. As shown in  FIG. 6 , the inner surface  28   c  of the concave portion  28  may be smooth. The surface roughness of the inner surface  28   c  may be equal to the surface roughness of the front surface  40   a  and the rear surface  40   b  of the coating sheet  40  or the surface roughness thereof may be smaller than those of the front surface  40   a  and the rear surface  40   b.    
     As shown in  FIG. 5 , a hole  120   b  may be formed in the membrane lamination body  120 , a hole  41  may be formed in the coating sheet  40 , and then the light emitting diode device  29  may be located inside the holes  120   b  and  41 . In addition, the light emitting diode device  29  may be covered by the shielding portion  32  of the mask sheet  30 . 
     In these embodiments, since the coating sheet  40  as the light guiding sheet may be laminated on the membrane lamination body  120 , the membrane lamination body  120  may be formed of a non-transparent material. 
       FIG. 7  is an enlarged view showing a section of the input device according to an exemplary embodiment.  FIG. 8  is an enlarged view showing a structure of an illumination function portion. 
     As shown in  FIG. 7 , in an input device  200 , an illumination function portion  220  may be formed on a chassis  202 , a support plate  211  formed as a metal plate such as aluminum may be formed on the illumination function portion  220 , and a membrane lamination body  212  may be formed on the support plate  211 . In portions provided with manipulation portions  210   a , first and second support pieces  211   a  and  211   b  of the support plate  211  are bent upward. In the portions provided with the manipulation portions  210   a , a pair of the first support pieces  211   a  may be formed so as to be distant from each other in a direction perpendicular to a paper sheet of  FIG. 7 , and a pair of the second support pieces  211   b  may be formed so as to be distant from each other in a direction perpendicular to the paper sheet. A hole  212   a  may be opened to the membrane lamination body  212 , and the first and second support pieces  211   a  and  211   b  may protrude upward from the membrane body  212  through the hole  212   a.    
     Each manipulation portion  210   a  may be provided with a key top  215 , and first and second movable support members  216  and  217  may be formed between the key top  215  and the support plate  211 . In the first movable support member  216 , one end  216   a  may be supported to the first support piece  211   a  so as to be rotatable, and the other end  216   b  may be supported to the lower portion of the key top  215  so as to be rotatable and slidable in the transverse direction. In the second movable support member  217 , one end  217   a  may be supported to the lower portion of the key top  215  so as to be rotatable, and the other end  217   b  may be supported to the second support piece  211   b  so as to be rotatable and slidable in the transverse direction. The center portions of the first movable support member  216  and the second movable support member  217  may be connected to each other so as to be rotatable, and hence the first movable support member  216  and the second movable support member  217  may constitute an X-shaped support link. 
     An elastic member  218  may be formed between the membrane lamination body  212  and the key top  215 . The elastic member  218  may be formed of synthetic rubber, and may be an urging member which may apply upward urging force to the key top  215  in a direction moving away from the membrane lamination body  212 . The inside of the lower portion of the elastic member  218  may be a cavity, and a downward pressing convex portion  218   a  may be integrally formed with the cavity. 
     The membrane lamination body  212  may be formed by laminating a lower flexible sheet  212   b , an upper flexible sheet  212   c , and a spacer sheet  212   d  interposed between both flexible sheets  212   b  and  212   c . In a portion facing the pressing convex portion  218   a  of the elastic member  218 , a hole may be formed in the spacer sheet  212   d , and an input function portion  219  may be formed at the portion. In the input function portion  219 , a front surface of the lower flexible sheet  212   b  and a rear surface of the upper flexible sheet  212   c  may be respectively provided with contact electrodes which face each other. In addition, the front surface of the lower flexible sheet  212   b  and the rear surface of the upper flexible sheet  212   c  may be provided with a lead pattern of a conductive layer electrically connected to the contact electrodes formed in the input function portions  219 . 
     In the manipulation portion  210   a , when the key top  215  is pressed, one end  216   a  of the first movable support member  216  may be rotated about an engagement portion engaging with the first support piece  211   a , and one end  217   a  of the second movable support member  217  may be rotated at the lower portion of the key top  215  so as to move down the key top  215 . At this time, the elastic member  218  may be pressed down by the key top  215 , and the pressing convex portion  218   a  and the input function portion  219  may be pressed so that the contacts of the input function portion  219  contact with each other. In this manner, a key input signal may be obtained. 
     The illumination function portion  220  may include a reflection sheet  221  which may be formed on the chassis  202 , a light guiding sheet  222  which may be formed thereon, and a mark sheet  223  which may be laminated thereon. As shown in  FIG. 8 , a hole  221   a  may be opened to an end of the reflection sheet  221 , and a hole  222   a  may be opened to an end of the light guiding sheet  222 . A flexible interconnection substrate may be adhered onto the chassis  202 , and a light emitting diode device  224  mounted to the flexible interconnection substrate may be inserted into the holes  221   a  and  222   a  so as to serve as a light source which applies light to the inside of the light guiding sheet  222 . 
     The light emitting diode device  224  may be formed by accommodating a bare tip of the light emitting diode in a transparent package. Since the light emitting diode device  224  faces an end surface  222   b  of the light guiding sheet  222  inside the hole  222   a , the light emitted from the light emitting diode device  224  is guided from the end surface  222   b  to the inside of the light guiding sheet  222 . 
     In  FIG. 8 , the light guiding sheet  222  may be depicted to have a comparatively thick dimension, but in fact, the thickness of the light guiding sheet  222  may be less than approximately mm, and may be less than approximately 500 μm. In this embodiment, the thickness of the light guiding sheet  222  is approximately 300 μm. 
     The light guiding sheet  222  may be formed as a flat surface of a mirror surface so that a front surface  222   c  facing the manipulation portion  210   a  and a rear surface  222   d  facing the chassis  202  may be smooth. In the light guiding sheet  222 , a reflection region  225  having a predetermined area may be separately set, and the reflection region  225  may be provided with plural concave portions  230 . 
     Each concave portion  230  may be formed in such a manner that energy such as a CO 2  laser may be applied to an extremely small area of the rear surface  222   d  of the light guiding sheet  222  so as to decompose and remove a part of a material forming the light guiding sheet  222 . For this reason, the light guiding sheet  222  may be formed of a material which may be transparent and may be decomposed by energy of the laser. As a transparent material which may be thin, has comparatively high strength, and may be decomposed by energy of the laser, for example, polycarbonate, urethane, silicon, or the like may be used. 
     Since the concave portion  230  may be formed in such a manner that energy of a minute spot laser may be applied to the rear surface  222   d  of the light guiding sheet  222  so as to decompose and remove a part of the material forming the light guiding sheet  222 , a shape of an opening of the concave portion  230  when seen from the rear surface  222   d  may be a circular shape. In addition, the opening diameter becomes gradually small in a direction toward the bottom portion of the concave portion  230 , the bottom portion may be formed in a concave spherical surface shape, and then the entire inner surface of the concave portion  230  may be formed in a concave curve surface shape. Further, since the concave portion  230  may be formed by decomposing the material forming the light guiding sheet, the inner surface of the concave portion  230  may be formed as a smooth surface, that is, a mirror surface throughout the entire area thereof. Herein, the smooth surface or the mirror surface indicates that the surface roughness may be equal to the surface roughness of the front surface  222   c  and the rear surface  222   d . Further, the smooth surface or the mirror surface may indicate such a characteristic that a diffused reflection of the light may not occur in the inner surface of the concave portion  230  and the light is reflected on the basis of the principle of the incident angle and the reflection angle inside the sheet in accordance with the angle of the inner surface when the light propagated through the inside the light guiding sheet  222  contacts with the inner surface thereof. In addition, the shape and the formation method of the concave portion  230  may be the same as those of the above-described embodiments. 
     As shown in  FIG. 8 , light L emitted from the light emitting diode device  224  so as to be incident from the end surface  222   b  into the light guiding sheet  222  may be propagated through the inside of the light guiding sheet  222  by repeating the reflection in the front surface  222   c  and the reflection in the rear surface  222   d . When the light propagated through the inside of the light guiding sheet  222  contacts with the inner surface of the concave portion  230 , the light may be reflected toward the inside of the light guiding sheet  222  so that the incident angle and the reflection angle are substantially equal to each other with respect to an imaginary plane contacting with the inner surface of the concave portion  230  at the light contact position, and the light is directed to the front surface  222   c . Then, the manipulation portion  210   a  may be illuminated by the light emitted from the front surface  222   c  of the light guiding sheet  222 . 
     As shown in  FIG. 8 , a body portion  215   a  of the key top  215  may be formed of a semitransparent translucent material or a transparent material such as polycarbonate, and a surface of the body portion  215   a  may be provided with a coating layer  215   b  which may be formed by coating or nonelectrolytic plating so as not to allow light to pass therethrough. An illumination display portion  215   c  may be formed by removing a part of the coating layer  215   b  using a CO 2  laser or the like. 
     As shown in  FIG. 8 , the mask sheet  223  laminated on the light guiding sheet  222  may include a light shielding portion  223   a  and a light transmitting portion  223   b . The light shielding portion  223   a  may be formed by painting a surface of a transparent sheet in black or is formed of a non-transparent sheet. The light transmitting portion  223   b  may be formed in an opening or a transparent portion of the sheet. The light transmitting portion  223   b  may be located right above the reflection region  225 , and may be formed to have the same area as that of the reflection region  225  or an area slightly wider than that of the reflection region  225 . A portion excluding the upper region of the reflection region  225  may be covered by the light shielding portion  223   a , and the light shielding portion  223   a  may exist below a gap between the adjacent key tops  215 . 
     As shown in  FIG. 8 , the reflection sheet  221  may be disposed below the light guiding sheet  222 . The surface of the reflection sheet  221  may be a reflection surface having a metallic color or a white color, and is capable of reflecting the light leaking downward from the rear surface  222   d  of the light guiding sheet  222  toward the inside of the light guiding sheet  222 . In addition, the inner surface of the concave portion  230  may be a mirror surface. In the light propagated through the inside of the light guiding sheet  222  and located at the inner surface of the concave portion  230 , most of the light components may be reflected in the inside of the light guiding sheet  222  due to a difference in refractive index between the light guiding sheet  22  and air, the reflection sheet  221  may not be particularly provided. 
     As shown in  FIG. 7 , the metallic support plate  211  may exist on the illumination function portion  220 . However, in the support plate  211 , an opening  211   c  may be formed on at least the reflection region  225  so that the support plate  211  does not disturb the transmission of the light. 
     In addition, the membrane lamination body  212  and the first and second movable support members  216  and  217  and the elastic member  218  may be formed of a transparent material or a semitransparent material which may allow the light to pass therethrough. Accordingly, the light emitted upward by the concave portion  230  of the reflection region  225  may be applied to the key top  215  through the membrane lamination body  212 , the first and second movable support members  216  and  217 , and the elastic member  218 . 
     Alternatively, the first and second movable support members  216  and  217 , the elastic member  218 , and the like may be formed of a white synthetic resin material so that the light is reflected and diffused by the surfaces thereof, and the light passing through the membrane body  212  may be reflected or diffused so as to be applied to the key top  215 . 
     As shown in  FIG. 8 , when the light propagated through the inside of the light guiding sheet  222  contact with the inner surface  233  of the concave portion  230  inside the sheet, the light may be mainly reflected toward the front surface  222   c . However, since the concave portion  230  may be formed in the same shape as that of the concave portion  230  as shown in  FIGS. 6A ,  6 B, and  6 C, as the dimension D of the concave portion  230  may be large and the inclined angle θ of the inner surface may be large, it may be possible to increase an ability of directing the light upward in the perpendicular direction. In addition, as the depth D of the concave portion  230  may be large and the inclined angle θ of the inner surface is large, it may be possible to increase the sum of the intensity of the light reflected by the inner surface among the light propagated through the inside of the light guiding sheet  222 . 
     Accordingly, when the opening area φ or the depth D of the concave portion  230  inside the same light guiding sheet  222  is differently set in accordance with the distance from the reflection region  225  to the light emitting diode device  224  as the light source, the width of the reflection region  225 , or the size of the illumination display portion  215   c , it may be possible to easily reduce a difference between the light intensities due to a difference in the distance from the light emitting diode device  224  to the reflection region  225 . In addition, since it may be possible to increase the directivity when reflecting the light toward the illumination display portion  215   c  using the concave portion  230 , for example, even when the mask sheet  223  does not exist, it may be possible to reduce an amount of the light leaking upward from the gap between the adjacent key tops  215 . 
     In the arrangement of the concave portions  230 , the depth D of the concave portion  230  formed in the reflection region  225  distant from the light emitting diode device  224  may be set to be larger than that of the reflection region  225  adjacent to the light emitting diode device  224 . As a result, that the angle θ may be set to be large. In addition, even in the same reflection region  225 , the depth D and the angle θ may become gradually large in a direction moving away from the light emitting diode device  224 . 
     In addition, the arrangement density of the concave portions  230  formed in the reflection region  225  distant from the light emitting diode device  224  may be set to be higher than that of the reflection region  225  adjacent to the light emitting diode device  224 . Further, even in the same reflection region  225 , the arrangement density may be set to be high in a direction moving away from the light emitting diode device  224 . 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims of the equivalents thereof. 
     Accordingly, the embodiments of the present inventions are not to be limited in scope by the specific embodiments described herein. Further, although some of the embodiments of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art should recognize that its usefulness is not limited thereto and that the embodiments of the present inventions can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the embodiments of the present inventions as disclosed herein. While the foregoing description includes many details and specificities, it is to be understood that these have been included for purposes of explanation only, and are not to be interpreted as limitations of the invention. Many modifications to the embodiments described above can be made without departing from the spirit and scope of the invention.