Abstract:
A display device is disclosed, which includes: a display panel; and a backlight module corresponding to the display panel. The backlight module includes: a light source; and a light guide plate adjacent to the light source and having a surface and a light guide dot. The light guide dot comprises a first valley and a second valley, the first valley has a first valley point, and the second valley has a second valley point. On the basis of the surface of the light guide plate as a reference surface, the first valley is recessed into the reference surface, the second valley is recessed into the reference surface, a distance from the first valley point to the reference surface is defined as a first depth, a distance from the second valley point to the reference surface is defined as a second depth, and the first depth is different from the second depth.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefits of the Taiwan Patent Application Serial Number 103112278, filed on Apr. 2, 2014, the subject matter of which is incorporated herein by reference. 
         [0002]    This application is a continuation (CA) of U.S. Patent application for “DISPLAY DEVICE”, U.S. application Ser. No. 14/621,319 filed Feb. 12, 2015, and the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a display device and, more particularly, to a display device equipped with a light guide plate with a specific structure. 
         [0005]    2. Description of Related Art 
         [0006]    As the electronic products progressed, the demands for the same are also increased. For display devices, display quality thereof is one item that consumers request. Backlight modules are one essential unit in the display devices, and the efficiency thereof is also one factor related to the display quality of the display device. In general, the backlight module is assembled with a rear frame, a light guide plate, a light source and plural optical films, and provides light into the display panel. 
         [0007]    The general used light source is a linear light source or a point light source. If it is desired to evenly illuminate light into the display panel, except for disposing the optical films properly, the light guide plate is used to firstly scatter the light from the light source. In the general backlight module, the light from the light source is firstly emitted into the light guide plate, followed by scattering with the light guide plate, passing through plural optical films and illuminating into the display panel. In order to obtain the best scattering effect of the light guide plate, a micro-pattern is formed on a reflection plane (i.e. a side opposite to the light emitting surface of the light guide plate with the display panel disposed thereon) of the light guide plate. 
         [0008]    Herein, the micro-pattern on the light guide plate is one main factor related to the light scattering effect thereof Therefore, it is desirable to provide a light guide plate with specific structure to improve the light emitting amount thereof. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to provide a display device, wherein the backlight module used therein comprises a light guide plate with a specific structure to increase light emitting amount of the backlight module. 
         [0010]    Another object of the present invention is to provide a method for manufacturing a light guide plate for a backlight module of a display device, which can be used to produce a light guide plate capable of increasing light emitting amount of the backlight module in a simple and rapid way. 
         [0011]    To achieve the object, the method for manufacturing the light guide plate for the backlight module of the display device comprises the following steps: providing a mold disposed with at least one protrusion and at least one recess on a surface thereof, wherein each recess corresponds to and is surrounded with the protrusion; providing a material for forming a light guide plate on the mold; and curing the material for forming the light guide plate and removing the mold to obtain the light guide plate. 
         [0012]    After the aforementioned steps, a light guide plate with a specific structure in one aspect of the present invention is obtained, in which at least one light guide dot with an embossment and a cavity is disposed on a surface of the light guide plate, and the cavity surrounds the embossment. 
         [0013]    When the surface of the light guide plate is considered as a reference surface, the embossment is protruded from the reference surface, the cavity is recessed into the reference surface, the embossment has a (maximum) first width (w 1 ) based on the reference surface, the cavity has a (maximum) second width (w 2 ) based on the reference surface, and the (maximum) first width (w 1 ) is larger than the (maximum) second width (w 2 ) (w 1 &gt;w 2 ). Preferably, a ratio of the (maximum) second width to the (maximum) first width is larger than or equal to 0.05 as well as less than or equal to 0.6 (0.05≦w 2 /w 1 ≦0.6). In addition, a ratio of a height (H) of the embossment to a depth (D) of the cavity is in a range from 1 to 2 (1≦H/D≦2). 
         [0014]    When the light guide plate with the aforementioned specific structure is applied on a backlight module, the obtained backlight module can be assembled with a display panel to obtain a display device of the present invention. Hence, the display device of the present invention comprises: a display panel; and a backlight module corresponding to the display panel, wherein the backlight module comprises: a light source; and the aforementioned light guide plate adjacent to the light source. 
         [0015]    In the present invention, the light guide plate may comprise a first region and a second region, wherein the first region locates between the second region and the light source, at least two light guide dots are selectively disposed on the surface of the light guide plate in the second region thereof, and the light guide dots are adjacently disposed. Preferably, the cavities of two adjacent light guide dots are integrated into a concave. Especially, when the surface of the light guide plate is considered as a reference surface, the cavities are recessed into the reference surface, and the concave located between the embossments has a maximum depth. 
         [0016]    Except for the aforementioned light guide plate, another light guide plate with a specific structure can also be obtained in another aspect of the present invention after the aforementioned steps for manufacturing the same, which can also be applied to a backlight module and assembled with a display panel to obtain a display device of the present invention. Hence, the display device of another aspect of the present invention comprises: a display panel; and a backlight module corresponding to the display panel, wherein the backlight module comprises: a light source; and a light guide plate of this aspect adjacent to the light source and having a surface. The light guide plate of this aspect comprises: a first region and a second region, and the first region locates between the second region and the light source, wherein at least one light guide dot with two first embossments and a cavity is disposed on the surface of the light guide plate in the second region thereof, and the first embossments are disposed in the cavity. 
         [0017]    When the surface of the light guide plate is considered as a reference surface, the first embossments are respectively protruded from the reference surface, and the cavity is recessed into the reference surface. In addition, the cavity has a minimum second width (w 2 ) and a maximum third width (w 3 ), and a ratio of the minimum second width (w 2 ) to the maximum third width (w 3 ) is in a range from 0.05 to 0.2 (0.05≦w 2 /w 3 ≦0.2). In addition, the light guide dot may further selectively comprise a second embossment disposed in the cavity. Furthermore, the cavity preferably has a maximum depth between two adjacent first embossments. 
         [0018]    Except for the aforementioned light guide plate, another light guide plate with a specific structure can also be obtained in further another aspect of the present invention after the aforementioned steps for manufacturing the same, which can also be applied to a backlight module and assembled with a display panel to obtain a display device of the present invention. Hence, the display device of further another aspect of the present invention comprises: a display panel; and a backlight module corresponding to the display panel, wherein the backlight module comprises: a light source; and a light guide plate of this aspect adjacent to the light source and having a surface. The light guide plate of this aspect comprises: a first region and a second region, and the first region locates between the second region and the light source, wherein at least one light guide dot has two embossments, two cavities and a concave, two embossments are adjacently disposed, each cavity respectively corresponds to and surrounds the embossment, and the concave is disposed between two adjacent embossments. 
         [0019]    When the surface of the light guide plate is considered as a reference surface, the embossments are respectively protruded from the reference surface, and the cavities and the concave are respectively recessed into the reference surface. Preferably, a depth of the concave is larger than that of the cavity. 
         [0020]    In the light guide plate and the display device comprising the same of the aforementioned aspect of the present invention, the cavity and/or the concave is recessed into the surface of the light guide plate (i.e. the reference surface), and the cavity and/or the concave may have different depth. 
         [0021]    Furthermore, in the light guide plate and the display device comprising the same of the aforementioned aspect of the present invention, the embossment, the first embossment, the second embossment, the cavity and/or the concave may respectively have a rough surface. 
         [0022]    Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a perspective view of a mold for manufacturing a light guide plate according to one preferred embodiment of the present invention; 
           [0024]      FIG. 2  is a cross-sectional view showing a part of a mold for manufacturing a light guide plate according to one preferred embodiment of the present invention; 
           [0025]      FIG. 3  is a perspective view of manufacturing a light guide plate through a molding process with the mold according to one preferred embodiment of the present invention; 
           [0026]      FIG. 4  is a perspective view of a light guide plate according to one preferred embodiment of the present invention; 
           [0027]      FIG. 5  is a perspective view of a backlight module according to one preferred embodiment of the present invention; 
           [0028]      FIG. 6  is a perspective view of a display device according to one preferred embodiment of the present invention; 
           [0029]      FIGS. 7A to 7C  are cross-sectional views showing parts of a light guide plate according to one preferred embodiment of the present invention; 
           [0030]      FIG. 8  is a cross-sectional view showing a part of a light guide plate according to another preferred embodiment of the present invention; 
           [0031]      FIG. 9  is a diagram showing the relation between intensity and angles of emitting light in regions B and B′ of a light guide plate of  FIG. 4  in one preferred embodiment of the present invention; 
           [0032]      FIG. 10  is a diagram showing the relation between intensity and angles of emitting light in regions C and C′ of a light guide plate of  FIG. 4  in one preferred embodiment of the present invention; 
           [0033]      FIG. 11  is a diagram showing the relation between intensity and angles of emitting light by using a light guide plate having a structure of  FIG. 2  and different w 2 /w 1  ratio; 
           [0034]      FIG. 12  is a diagram showing the relation between flux of emitting light and w 2 /w 1  ratios by using a light guide plate having a structure of  FIG. 2  and different w 2 /w 1  ratio, in which a depth of a cavity is twofold of a height of an embossment; 
           [0035]      FIG. 13  is a diagram showing the relation between flux of emitting light and w 2 /w 1  ratios by using a light guide plate having a structure of  FIG. 7A  and different w 2 /w 1  ratio, in which a height of an embossment is twofold of a depth of a cavity; and 
           [0036]      FIG. 14  is a diagram showing the relation between intensity and angles of emitting light by using a light guide plate having a structure of  FIG. 7A  and different w 2 /w 1  ratio. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0037]    The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 
         [0038]    Hereinafter, the structures of the light guide plate (LGP), the backlight module and the display device and the methods for manufacturing the same of the present invention are illustrated in detail. 
         [0039]    As shown in  FIG. 1 , a mold  1  with a patterned surface  11  is firstly provided. In the present embodiment, the mold  1  can be prepared with any material for forming the mold generally used in the art, such as metal. In addition, in the present embodiment, the pattern can be formed on the surface  11  of the mold  1  through any patterning manner generally used in the art, such as etching and laser. 
         [0040]      FIG. 2  is a cross-sectional view of a region A in  FIG. 1  along an I-I′ line. As shown in  FIG. 2 , a protrusion  111  and a recess  112  is formed on the surface  11  of the template  1 , and the protrusion  111  surrounds the recess  112 . Herein, the protrusion  111  protrudes from the surface  11  thereof, and the recess  112  recesses into the surface  11  thereof. In addition, the recess  112  has a first width w 1  and a depth D 1 , and the protrusion  111  has a second width w 2  and a height based on the surface  11  of the mold  1 . 
         [0041]    Next, as shown in  FIG. 3 , a LGP  2  of the present embodiment is obtained through a molding process with the mold  1 . More specifically, in the preset embodiment, a material for the LGP is applied onto the mold  1 , followed by curing the same. After the mold  1  is removed, the LGP  2  of the present embodiment is obtained, as shown in  FIG. 4 . Herein, the material for the LGP can be any material generally used in the art, such as PMMA. In addition, in the present embodiment, the material for the LGP can be applied onto the mold  1  through any process generally used in the art, such as injection molding, coating (for example, dip coating, roll coating, printing, and spin coating), and imprinting. Furthermore, in the present embodiment, the material for the LGP can be cured through any process generally used in the art, such as photo curing and thermal curing. For removing the mold, a detaching layer (not shown in the figure) can be firstly formed on the mold  1 , followed by applying the material for the LGP thereon. 
         [0042]    For the conventional method for manufacturing the LGP, a laser patterning process is directly performed on the plate for forming the LGP, but this process is expensive and time consuming However, the LGP of the present embodiment is produced with a molding process. Hence, in the process for manufacturing the LGP of the present embodiment, the process for pattering the mold is only performed for one time, and then plural LGPs can be sequentially obtained through the molding process with the mold. Therefore, the LGP of the present embodiment can be produced in a rapid, simple and low cost way. 
         [0043]    Herein, light in all directions was illuminated into a LGP having the structure of  FIG. 2  and prepared with PMMA, and the intensity of emitting light guided by the LGP between −80 degree and 80 degree was measured. The results are shown in  FIG. 11  and  FIG. 12 , which are diagrams showing the relations between intensity and angles of emitting light by using the LGP having a structure of  FIG. 2 . Herein,  FIG. 11  shows the relation between intensity and angles of emitting light by using the LGP having different w 2 /w 1  ratio, in which a depth D 1  of a cavity is twofold of a height H of an embossment, and  FIG. 12  shows the relation between flux and w 2 /w 1  ratios. The results indicate that a relative high light emitting amount can be maintained when a ratio of the second width w 2  to the first width w 1  is larger than or equal to 0.3 and less than or equal to 1 (0.3≦w 2 /w 1 ≦1). In addition, as shown in  FIG. 11  and  FIG. 12 , in the case that the first width w 1  is greater than the second width w 2 , the proportion of the second width w 2  relative to the first width w 1  has to be large enough to maintain the relative high light emitting amount. This result indicates that the proportion of the protrusion relative to the recess has to be high enough in order to obtain a preferred high light emitting amount. 
         [0044]    After the LGP of the present embodiment is obtained through the aforementioned process, the obtained LGP is assembled with other units for a backlight module to obtain the backlight module of the present embodiment.  FIG. 5  is a perspective view showing the backlight module with the aforementioned LGP of the present embodiment. Herein, the LGP  2  is disposed on a rear frame  4 , and a light source  3  is disposed adjacent to the LGP  2 . In the present embodiment, the light source  3  comprises plural LEDs, but the present invention is not limited thereto. In addition, at least one optical film  5  is further disposed on the LGP  2 . In the present embodiment, the optical film  5  comprises a diffusion layer  51 , a first prism layer  52 , a second prism layer  53  and another diffusion layer  54  sequentially formed on the LGP  2 . Herein, as shown in  FIG. 4  and  FIG. 5 , the LGP  2  of the present embodiment is defined to comprise a first region R 1  and a second region R 2 , and the first region R 1  locates between the second region R 2  and the light source  3 . The “first region R 1 ” is adjacent to the light source  3  and can be considered as a near light region, and the “second region R 2 ” is relative far from the light source  3  and can be considered as a far light region. However, in other embodiments, the first region R 1  and the second region R 2  are not limited to the regions indicated in  FIG. 5 , as long as the first region R 1  locates between the second region R 2  and the light source  3 . 
         [0045]    Finally as shown in  FIG. 6 , a display panel  7  is disposed on the aforementioned backlight module  6  to obtain the display device of the present embodiment. In the present embodiment, the display panel  7  can be the known one in the art, such as a liquid crystal display panel. In addition, a touch panel  8  may be selectively disposed on the display panel  7 . However, in other embodiment, the touch panel  8  can be directly integrated into the display panel  7  or disposed inside the display panel  7  (not shown in the figure). 
         [0046]    Hereinafter, the structure of the LGP of the present embodiment is illustrated in detail. 
         [0047]    As shown in the region A in the first region R 1  of  FIG. 4 , a light guide dot  21 A with an embossment  211  and a cavity  212  is disposed on the surface  22  of the LGP  2 , and the cavity  212  surrounds the embossment  211 . When the surface  22  of the LGP  2  is considered as a reference surface, the embossment  211  is protruded from the reference surface, and the cavity  212  is recessed into the reference surface. Herein, the cavity  212  may have different depths. 
         [0048]      FIG. 7A  is a cross-sectional view showing the region A of  FIG. 4  along an LA-LA′ line. In the case that the surface  22  of the LGP  2  is considered as a reference surface, the embossment  211  is protruded from the reference surface, and the cavity  212  is recessed into the reference surface. More specifically, the cavity  212  shown in  FIG. 4  is disposed to surround the embossment  211 ; and the first embossment  2111  shown in  FIG. 7A  is the embossment  211  of  FIG. 4 , the cavity  212  shown in  FIG. 4  can be divided into the left first cavity  2121  and the right second cavity  2122  in  FIG. 7A , and the first cavity  2121  and the second cavity  2122  may have identical or different depth. In this embodiment, the depths of the first cavity  2121  and the second cavity  2122  are different. In addition, as shown in  FIG. 7A , the first embossment  2111  corresponding to the embossment  211  of  FIG. 4  has a rough surface  2111   a,  and the first cavity  2121  and the second cavity  2122  corresponding to the cavity  212  of  FIG. 4  also have rough surfaces  2121   a,    2122   a.  However, other light guide dots in the LGP of the present embodiment or other embodiments are not limited to have the structure shown in  FIG. 7A , as long as the cavities  212  (as shown in  FIG. 4 ) in different region have different depths. In the present embodiment, a ratio of the height H of the first embossment  2111  (i.e. the embossment  211  of  FIG. 4 ) to the depth D 1  of the first cavity  2121  or the depth D 2  of the second cavity  2122  (i.e. the cavity  212  of  FIG. 4 ) is in a range from 1 to 2 (1≦H/(D 1  or D 2 )≦2). The first embossment  2111  has a first width w 1 , the first cavity  2121  and the second cavity  2122  respectively have a second width w 2 , and the first width w 1  is larger than the second width w 2 . Preferably, a ratio of the second width w 2  to the first width w 1  is larger than or equal to 0.05 as well as less than or equal to 0.6 (0.05≦w 2 /w 1 ≦0.6). In other embodiment of the present invention, the width, the height and the depth of the embossment and the cavity is not particularly limited, as long as the ratio thereof satisfies the aforementioned range. Herein,  FIG. 7A  only illustrated the cross-section of  FIG. 4  along the LA-LA′ line. However, the relation between the width, the height and the depth of the embossment and the cavity are not limited to those obtained with a single cross-sectional line, and the width, the height and the depth of the embossment and the cavity can be obtained with plural different cross-sectional lines. Furthermore, the widths of the embossment and the cavity may be varied along different cross-sectional lines, and all of them are belonged to the scope of the present invention, as long as the embossment and the cavity respectively has a maximum first width and a maximum second width based on the surface of the LGP and the relation between the first width and the second width satisfies the aforementioned definition. 
         [0049]    As shown in the region B in the first region R 1  of  FIG. 4 , a light guide dot  21 B with two embossments  211  and an integrated cavity  212 ′ is disposed on the surface  22  of the LGP  2 , and the integrated cavity  212 ′ surrounds the embossment  211 . When the surface  22  of the LGP  2  is considered as a reference surface, the embossments  211  are protruded from the reference surface, and the integrated cavity  212 ′ is recessed into the reference surface. Herein, the integrated cavity  212 ′ may have different depths. 
         [0050]      FIG. 7B  is a cross-sectional view showing the region B of  FIG. 4  along an LB-LB′ line. Not only the light guide dot  21   a  of  FIG. 7A  is disposed on the LGP  2 , but also another light guide dot  21   b  is disposed thereon. In addition, the light guide dot  21   a  is adjacent to the light guide dot  21   b,  and a left first cavity  2121  and a right second cavity  2122  are integrated into a concave (i.e. a third cavity  2123 ). 
         [0051]    As shown in  FIG. 7B , two embossments  211  of  FIG. 4  are divided into a first embossments  2111  and a second embossments  2112 , and the integrated cavity  212 ′ of  FIG. 4  is divided into a left first cavity  2121 , a right second cavity  2122 , and a third cavity  2123  located between the first cavity  2121  and the second cavity  2122 . The depths of the first cavity  2121 , the second cavity  2122  and the third cavity  2123  may be identical or different. As shown in  FIG. 7B , the first cavity  2121 , the second cavity  2122  and the third cavity  2123  respectively have a depth D 1 , a depth D 2  and a depth D 3 . In the present embodiment, the depth D 3  of the third cavity  2123  is a maximum depth, but the present invention is not limited thereto. In addition, the first embossments  2111  and the second embossments  2112  respectively have heights H 1 , H 2 , which may be identical or different. In the present embodiment, a ratio of the height H 1  of the first embossments  2111  or the height H 2  of the second embossments  2112  (i.e. the embossment  211  of  FIG. 4 ) to the depth D 1  of the first cavity  2121 , the depth D 2  of the second cavity  2122  or the depth D 3  of the third cavity  2123  may be in a range from 1 to 2 (1≦(H 1  or H 2 )/(D 1 , D 2  or D 3 )≦2). In one embodiment, the first widths w 1  of the first embossments  2111  and the second embossments  2112  are larger than the second widths w 2  of the first cavity  2121 , the second cavity  2122  and the third cavity  2123 . Preferably, a ratio of the second width w 2  to the first width w 1  is larger than or equal to 0.05 as well as less than or equal to 0.6 (0.05≦w 2 /w 1 ≦0.6). In other embodiment of the present invention, the width, the height and the depth of the embossment and the cavity is not particularly limited, as long as the ratio thereof satisfies the aforementioned range. Herein,  FIG. 7B  only illustrated the cross-section of  FIG. 4  along the LB-LB′ line. However, the relation between the width, the height and the depth of the embossment and the cavity are not limited to those obtained with a single cross-sectional line, and the width, the height and the depth of the embossment and the cavity can be obtained with plural different cross-sectional lines. Furthermore, the widths of the embossment and the cavity may be varied along different cross-sectional lines, and all of them are belonged to the scope of the present invention, as long as the embossment and the cavity respectively has a maximum first width and a maximum second width based on the surface of the LGP and the relation between the first width and the second width satisfies the aforementioned definition. 
         [0052]    In addition, as shown in  FIG. 4  and  FIG. 7B , a border of the integrated cavity  212 ′ has a maximum third width w 3 , in which a ratio of the second width w 2  to the maximum third width w 3  is in a range from 0.05 to 0.2 (0.05≦w 2 /w 3 ≦0.2). However, other light guide dots in the LGP of the present embodiment or other embodiments are not limited to have the structure shown in  FIG. 7B , as long as the first embossments  2111  and the second embossments  2112  have different heights and widths as well as the first cavity  2121 , the second cavity  2122  and the third cavity  2123  may have different heights and widths. In addition, the relation between the second width w 2  and the third width w 3  are not limited to those obtained with a single cross-sectional line, and can be obtained with plural different cross-sectional lines. Furthermore, the second width w 2  and the third width w 3  may be varied along different cross-sectional lines, and all of them are belonged to the scope of the present invention, as long as the second width w 2  and the third width w 3  satisfies the aforementioned definition. 
         [0053]    In addition, only the region R 2  of the LGP  2  with two adjacent light guide dots  21   a,    21   b  formed thereon are illustrated (as shown in  FIG. 5  and  FIG. 7B ), but three adjacent light guide dots may be formed on the region R 2  of the LGP  2  in other embodiment (as shown in  FIG. 7C ). The structure of  FIG. 7C  is similar to that of  FIG. 7B , and not described repeatedly. 
         [0054]      FIG. 7C  is a cross-sectional view showing the region C in the region R 2  of the LGP shown in  FIG. 4  along an LC-LC′ line. When the light guide dot  21 B of  FIG. 7B  further comprises another embossment, the obtained light guide dot can be shown as the light guide dot  21 C in  FIG. 4  and in  FIG. 7C . As shown in  FIG. 7C , the light guide dot  21 ′ further comprises a second embossment  211 ′ disposed in the cavity  212 . 
         [0055]    When the light illuminated into the LGP, the embossment and the cavity formed thereon can break the total reflection of the illuminated light to guide the light outside the LGP. In addition, the rough surfaces of the embossment and the cavity on the LGP can scatter the illuminated light to make the guided light evenly illuminate into the display panel. 
         [0056]    When the material with low viscosity is used to form the LGP through an injection molding process, the LGP having the structures of  FIGS. 7A to 7C  can be obtained. When the material with high viscosity is used to form the LGP through an injection molding process, the LGP having the structures of  FIG. 8  can be obtained. 
         [0057]    In addition, as shown in  FIG. 4 , the LGP of the present embodiment comprises the light guide dots shown in  FIGS. 7A to 7C , but the present invention is not limited thereto. For example, in other embodiment of the present invention, the LGP can be formed to have two types of the light guide dots selected from those shown in  FIGS. 7A to 7C . Furthermore, the arrangement of the light guide dots is not limited to the linear arrangement shown in  FIG. 4 , and the combination and the arrangement of the light guide dots shown in  FIGS. 7A to 7C  can be adjusted if it is required. 
         [0058]    Herein, the light emitting efficiency of the LGP of the present invention is measured. 
         [0059]    In the present test, light in all directions was illuminated into LGPs respectively having the structures shown in regions B, B′, C and C′ of  FIG. 4 , and the intensity of emitting light guided by the LGPs between −80 degree and 80 degree was measured. The results are shown in  FIG. 9  and  FIG. 10 . 
         [0060]    As shown in  FIG. 9 , for the LGPs having the structures shown in the regions B and B′ of  FIG. 4 , there is no significant difference in the relation between the intensity and the angles of the emitting light. However, regarding the light emitting amount through the intensity integral transforms, the maximum intensity of the emitting light is 0.83 (a.u.) for the LGP having the structure shown in the region B′ of  FIG. 4 , but 0.8553 (a.u.) for the LGP having the structure shown in the region B of  FIG. 4 . Hence, the gain of the light emitting amount in the LGP having the structure of the region B can be increased about 2.96%, compared to that of the region B′. In addition, as shown in  FIG. 10 , for the LGPs having the structures shown in the regions C and C′ of  FIG. 4 , there is no significant difference in the relation between the intensity and the angles of the emitting light. However, regarding the light emitting amount through the intensity integral transforms, the maximum intensity of the emitting light is 1.076 (a.u.) for the LGP having the structure shown in the region C′ of  FIG. 4 , but 1.077 (a.u.) for the LGP having the structure shown in the region C of  FIG. 4 . Hence, the gain of the light emitting amount in the LGP having the structure of the region C can be increased about 0.09%, compared to that of the region C′. These results indicate that the gain of the LGP having two adjacent embossment  211  compared to that having two separated embossment  211  (2.96%) is higher than the gain of the LGP having three adjacent embossment  211  compared to that having three separated embossment  211  (0.09%). Hence, for the purpose of obtaining the best scattering effect in the LGP, the light guide dots  21 B,  21 C shown in  FIGS. 7B and 7C  can be selected to form on the LGP, especially in the far light region (i.e. the region R 2 ) of the LGP to obtain the maximum light emitting amount. In addition, in a limited area, the light guide dot  21 B shown in  FIG. 7C  can be selected to form the LGP to obtain the maximum gain of the light emitting amount. 
         [0061]    In addition, the relation between intensity and angles of emitting light by using the LGP having the structure of  FIG. 7A  and different w 2 /w 1  ratio of the present invention is also measured according to the aforementioned method. The results are shown in  FIGS. 13 and 14 , which indicate that a relative high and ideal light emitting amount can be obtained when a ratio of the second width w 2  to the first width w 1  is larger than or equal to 0.05 as well as less than or equal to 0.6 (0.05≦w 2 /w 1 ≦0.6). 
         [0062]    Furthermore, the display device provided by the present invention can be applied to any electronic device for displaying images, such as a mobile phone, a notebook, a camera, a video camera, a music player, a navigation system, or a television. 
         [0063]    Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.