Patent Publication Number: US-6219117-B1

Title: Liquid crystal display device

Description:
This application is a divisional application of currently pending application Ser. No. 08/985,997, filed Dec. 5, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid crystal display device for guiding light from a backlight source to a light transmission member and irradiating a liquid crystal panel, and more specifically, to the improvement of the brightness of the liquid crystal panel. 
     2. Description of the Related Art 
     As shown in FIG. 11, a conventional ordinary liquid crystal display device is arranged such that: successively laminated on the back surface of a liquid crystal panel  31  are a protection/diffusion sheet  32 ; two lens sheets  33  disposed under the protection/diffusion sheet  32  for improving the brightness of light; a diffusion plate  34  disposed under the lens sheets  33  for diffusing the light; a light transmission member  35  composed of an acryl resin or the like and disposed below diffusion plate  34 , a light transmission member reflection pattern  35   b  formed on the bottom surface of the light transmission member  35  by silk print or when the light transmission member is molded for reflecting the light upward; and a reflection sheet  36  disposed under the light transmission member  35  for reflecting the light upward. Further, a backlight source  38  composed of a cold cathode fluorescent lamp (CCFL) or the like is disposed in a lamp holder  37  on the one end surface  35   a  of the light transmission member  35  and a U-shaped reflection film  39  is held in the lamp holder  37  on the upper, lower and back sides of the backlight source  38  to reflect the light from the backlight source  38  forward. 
     The above respective components are held by an upper holder  40  and a lower holder  41  as a frame member. 
     The light from the backlight source  38  and the light reflected at the reflection film  39  are irradiated to the one end surface  35   a  of the light transmission member  35  positioned forward of the backlight source  38  and the light from the end surface  35   a  is entered into the light transmission member  35 . Then, the incoming light can reach every point in the light transmission member  35  while irregularly reflecting therein. 
     The incoming light which irregularly reflects in the light transmission member  35  is reflected at the light transmission member reflection pattern  35   b  on the bottom surface of the light transmission member  35 , the reflection sheet  36  under the light transmission member  35  and so on in an approximately vertical direction and emerges from the upper surface of the light transmission member  35 . 
     At the time, the light from the backlight source  38  also emerges from the upper surface of the of the portion of the light transmission member  35  which is located on the other end surface (not shown) side thereof which is apart from the backlight source  38 . 
     The light emerged from the upper surface of the light transmission member  35  is caused to pass through the diffusion plate  34 , the lens sheets  33 , the protection/diffusion sheet  32  on the lens sheets  33  and so on so that it can irradiate the effective display area  31   a  of the liquid crystal panel  31  from the backside thereof. 
     In the liquid crystal display device described above, however, the light which irradiates the liquid crystal panel  31  includes two kinds of light beams. One of the light beams, that is, a first light beam is such that when the light which emerges from the backlight source  38  and the reflection film  39  and travels straight in an approximately horizontal direction enters the light transmission member  35 , the light irregularly reflects in the light transmission member  35  and the thus irregularly reflected light is reflected at the light transmission member reflection pattern  35   b  on the bottom surface of the light transmission member  35 , the reflection sheet  36  under the light transmission member  35  and so on while changing its direction approximately perpendicularly to the light transmission member  35 , then emerges upward from the upper surface of the light transmission member  35  and irradiates the entire surface of the effective display area  31   a  of the liquid crystal panel  31  from the backside thereof. 
     Whereas, the other of the light beams, that is, a second light beam is such that when an oblique light beam A shown by the arrow in FIG. 11 emerges from the backlight source  38  and the reflection film  39  obliquely upward with respect to the end surface  35   a  of the light transmission member  35  and enters the light transmission member  35 , the oblique light beam A passes through the light transmission member  35  straight in an obliquely upward direction without irregularly reflecting in it, emerges from the light transmission member  35  and irradiates, in addition to the first light beam, the portion of the effective display area  31   a  which is shown in the schematic plan view of the liquid crystal display device in FIG.  12  and located near to the edge  31   b  thereof in the vicinity of the backlight source  38 , for example, the portion of the effective display area  31   a  within the range of 10 mm from the edge  31   b  of the liquid crystal panel  31 . 
     Since the portion of the effective display area  31   a  within the range of 10 mm from the edge  31   b  of the liquid crystal panel  31  is irradiated by the composite light beam composed of both the first and second light beams, the above portion of the effective display area  31   a  is brighter than the other portion thereof and “glittering state” emission lines  31   c  are generated. Accordingly, there is a problem that the brightness of the effective display area  31   a  of the liquid crystal panel  31  is made uneven. 
     As a coutermeasure to cope with the above problem, the conventional liquid crystal display device has a black or gray colored portion  36   a  formed thereto by print or the like within the range of approximately 10 mm, which is near to the backlight source  38 , of the reflecting surface of the reflection sheet  36  under the light transmission member  35  to absorb a part of the first light beam so that the generation of the emission lines  1   c  is prevented by lowering the brightness of the effective display area  31   a  within the range of approximately 10 mm thereof near to the edge  31   b.    
     In the conventional liquid crystal display device, however, since the “glittering state” emission lines  31   c  which are generated to the effective display area  31   a  of the liquid crystal panel  31  are prevented by the provision of the black or gray colored portion  36   a  formed within the range of approximately 10 mm near to the backlight source  38  of the reflection sheet  36 , there is a problem that the surface brightness in the liquid crystal display area is lowered, although there is an effect that the light of the backlight source  38  is partly absorbed by the colored portion  36   a  and the quantity of light emerged upward from the light transmission member  35  is reduced and the generation of the emission lines is prevented. 
     As shown in FIGS. 13 and 14, another conventional liquid crystal display device has a reflector  59  whose interior is formed to a U-shape so as to encase a backlight source  38 . 
     A reflecting surface  59   b  to which glossy processing is applied is formed to the interior of the opening  59   a  of the reflector  59  so that the reflecting surface  59   b  reflects the light irradiated from the backlight source  38  forward and irradiates the end surface  55   a  of a light transmission member  55 . 
     Further, a case portion  59   c  on which the aforesaid respective components are placed is formed to the reflector  59  integrally therewith. The respective members are held by the reflector  59  having the case portion  59   c  and an upper holder  40  acting as a frame member. 
     According to the liquid crystal display device arranged as described above, in the liquid crystal panel  31  shown in FIG. 12 which shows the schematic plan view of the liquid crystal display device, there is a second light beam, that is, a reflected light beam C 1  which irradiates, in addition to the above first light beam, the portion of the effective display area  31   a  of the liquid crystal panel  31  which is located near to the edge portion  31   b  in the vicinity of the backlight source  38 , for example, the portion of the effective display area  31   a  of the liquid crystal panel  31  within the range of 10 mm from the edge  31   b.    
     The behavior of second light beam or the reflected light beam C 1  is such that since the above portion of the effective display area  31   a  is located near to the backlight source  38 , when an oblique light beam C shown by the arrow in FIG. 13 irradiates the surface of a reflection sheet  56  within the range of 10 mm from the end surface  56   a  thereof, it is reflected at the reflection sheet  56  and the thus reflected light beam C 1  passes through the light transmission member  55  straight in an obliquely upward direction without irregularly reflecting therein and emerges from the upper surface of the light transmission member  55  so as to irradiate the portion of the effective display area  31   a  within the range of 10 mm from the edge portion  31   b  of the liquid crystal panel  31 . 
     The second light beam includes, in addition to the reflected light beam C 1 , a reflected light beam D 1  which irradiates the portion the effective display area  31   a  within 10 mm from the edge  31   b  of the liquid crystal panel  31 . The behavior of the reflected light beam D 1  is such that when an oblique light beam D irradiates the lower plane portion  59   d  of the reflecting surface  59   b  of the reflector  59 , in which the backlight source  38  is encased, on the side thereof near to the light transmission member  55 , the oblique light beam D is reflected upward at the lower plane portion  59   d  and when the thus reflected light beam D 1  enters the light transmission member  55  from the end surface  55   a,  it passes through the light transmission member  55  likewise the reflected light beam C 1  and emerges from the upper surface of the light transmission member  55  so as to irradiate the portion of the effective display area  31   a  within the range of 10 mm from the edge portion  31   b  of the liquid crystal panel  31 . 
     As a result, since the portion of the effective display area  31   a  within the range of 10 mm from the edge  31   b  of the liquid crystal panel  31  is irradiated by the composite light beam composed of the first and second light beams, the portion is made brighter than the other area. Thus, there is a problem that the brightness of the effective display area  31   a  of the liquid crystal panel  31  is made uneven by the generation of “glittering state” emission lines  31   c.    
     As a coutermeasure to cope with the above problem, the conventional liquid crystal display device has a light: quantity control portion  56   b  of, for example, black or gray formed by print or the like to the reflection sheet  56  under the light transmission member  55  within the range of 10 mm from the end surface  56   a  thereof for partly absorbing the second light beam so that the generation of the emission lines  1   c  is prevented by lowering the brightness of the effective display area  31   a  of the liquid crystal panel  31  within the range of approximately 10 mm thereof which is located near to the edge  31   b  as shown in FIG.  14 . 
     In the aforesaid conventional liquid crystal display device, since the light quantity control portion  56   b  composed of the colored portion of for example, black or gray is formed by print or the like to the reflection sheet  56  within the range of 10 mm from the end surface  56   a  thereof as shown in FIG. 14 to absorb the oblique light beams from the backlight source  38 , the reflected light beam C 1  resulting from the oblique light C can be absorbed. However, since the oblique light beam D irradiating the lower plane portion  59   d  of the reflecting surface  59   b  is not absorbed, it emerges as the reflected light beam D 1 . Thus, there is caused a problem that since the brightness of the effective display area  31   a  of the liquid crystal panel  31  is made uneven and the emission lines  31   c  are generated and accordingly it is difficult to discriminate characters etc. displayed on the effective display area  31   a.    
     SUMMARY OF THE INVENTION 
     As first means for solving the above problem, a liquid crystal display device comprises a liquid crystal panel; a diffusion plate disposed on the backside of the liquid crystal panel; a light transmission member disposed below the diffusion plate; a reflection sheet disposed under the light transmission member; a light source disposed on an end surface side of the light transmission member; and a light quantity control portion formed on at least one surface of the diffusion plate on the side thereof near to the light source. 
     As second means for solving the above problem, the light quantity control portion is formed of a dot patterns. 
     As third means for solving the above problem, the size of the dots of the dot pattern is increased on the side of the dots near to the light source and gradually reduced as the dots are far from the backlight source. 
     As fourth means for solving the above problem, the diffusion plate has one surface to which no glaring prevention processing is applied and the other surface to which glaring prevention processing is applied and the light quantity control portion is formed to the one surface which is not subjected to the glaring prevention processing using a white color. 
     As fifth means for solving the above problem, a liquid crystal display device comprises a liquid crystal panel; a light transmission member disposed below the liquid crystal panel; a reflection sheet disposed under the light transmission member; a backlight source disposed on an end surface side of the light transmission member; a reflector having a reflection surface for reflecting the light from the backlight source to the end surface side of the light transmission member; and a light quantity control portion formed to the reflection sheet on the side of thereof near to the backlight source and a light quantity control portion formed to the reflection surface of the reflector on the side thereof which is in contact with the reflection sheet in the fashion that the former light quantity control portion is continuous to the latter light quantity control portion. 
     As sixth means for solving the above problem, the light quantity control portion formed to the reflection surface of the reflector covers the range from the end surface of the light transmission member to just below the backlight source. 
     As seventh means for solving the above problem, a liquid crystal display device comprises a liquid crystal panel; a light transmission member disposed below the liquid crystal panel; a reflection sheet disposed under the light transmission member and having a light quantity control portion; a backlight source disposed on an end surface side of the light transmission member; a reflector having a reflection surface for reflecting the light from the backlight source to the end surface side of the light transmission member, wherein the reflection sheet is extended from the end surface of the light transmission member to the outside thereof on the side of the backlight source and the light quantity control portion is formed to the portion of the reflection sheet which is near to the end surface of the light transmission member and to the extended portion of the reflection sheet and the extended portion of the reflection sheet to which the light quantity control portion is formed is laid on the reflection surface of the reflector. 
     As eight means for solving the above problem, the light quantity control portion formed to the reflection surface of the reflector covers the range from the end surface of the light transmission member to just below the backlight source. 
     As ninth means for solving the above problem, the light quantity control portion is formed to an overall-printed pattern or a dot pattern. 
     As tenth means for solving the above problem, a liquid crystal display device comprises a liquid crystal panel; a light transmission member disposed below the liquid crystal panel; a reflection sheet disposed under the light transmission member; a backlight source disposed on an end surface side of the light transmission member; a reflector encasing the backlight source and having reflection walls formed to the periphery thereof and an opening continuous to the reflection walls; and light direction control walls formed to the opening of the reflector for controlling the direction of the light from the backlight source. 
     As eleventh means for solving the above problem, the light direction control walls are formed by projecting the upper and lower portions of the opening upward and downward. 
     As twelfth means for solving the above problem, the size of the opening of the light direction control walls is set to 50-95% of the thickness of the light transmission member. 
     As thirteenth means for solving the above problem, reflection layers composed of a material different from that of the reflection walls are formed to the insides of the light direction control walls. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of the main portion of a liquid crystal display device of a first embodiment according to the present invention; 
     FIG. 2 is a schematic plan view showing the liquid crystal display device of the first embodiment according to the present invention; 
     FIG. 3 is a plan view describing a dot pattern of a diffusion plate of the liquid crystal display device of the first embodiment according to the present invention; 
     FIG. 4 is a sectional view of the main portion of a liquid crystal display device of a second embodiment according to the present invention; 
     FIG. 5 is a sectional view of a main portion showing a modification of the second embodiment; 
     FIG. 6 is a schematic plan view describing a shape of a light quantity control portion of a reflecting sheet of the second embodiment; 
     FIG. 7 is a schematic plan view describing another example of the shape of the light quantity control portion of the reflecting sheet of the second embodiment; 
     FIG. 8 is a schematic plan view describing still another example of the shape of the light quantity control portion of the reflecting sheet of the second embodiment; 
     FIG. 9 is a sectional view of the main portion of a liquid crystal display device of a third embodiment according to the present invention; 
     FIG. 10 is an enlarged sectional view of the main portion of the liquid crystal display device of the third embodiment; 
     FIG. 11 is a sectional view of the main portion of a conventional liquid crystal display device; 
     FIG. 12 is a schematic plan view describing a state of emission lines of the conventional liquid crystal display device; 
     FIG. 13 is an enlarged sectional view of the main portion of another conventional liquid crystal display device; and 
     FIG. 14 is an enlarged sectional view of the main portion of the another conventional liquid crystal display device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A liquid crystal display device according to the present invention will be described with reference to FIG. 1 to FIG.  3 . 
     As shown in FIG. 1, the liquid crystal display device according to the present invention is arranged such that a light transmitting protection/diffusion sheet  2  is disposed on the back surface side of a liquid crystal panel  1  so as to diffuse light and protect the surface of lens sheets  3  under the protection/diffusion sheet  2 . Successively laminated under the protection/diffusion sheet  2  are: the two transparent lens sheets  3  which are laminated to each other and whose upper surface is arranged as a prism surface for improving the brightness of light; a diffusion plate  4  disposed under the two lens sheets  3  and composed of a film such as PET (polyethylene terephthalate) or the like, one surface of the film being subjected to frosted-glass-like glaring prevention processing and having fine uneven portions formed thereto and a light quantity control portion  4   a  being formed on the one surface at an end  4   b  thereof; a light transmission member  5  disposed below the diffusion plate  4  and molded of an acrylic resin or the like; a light transmission member reflection pattern  5   b  formed on the bottom surface of the light transmission member  5  for reflecting the light upward; and a reflection sheet  6  disposed under the light transmission member  5  for reflecting the light upward. 
     Further, a lamp holder  7  formed by molding or the like is disposed on the side of one end surface  5   a  of the light transmission member  5 , a backlight source  8  composed of a cold cathode fluorescent lamp (CCFL) or the like is disposed in the lamp holder  7  and a reflection film  9  is disposed around the backlight source  8  to irradiate the light from the backlight source  8  toward the end surface  5   a  of the light transmission member  5  disposed in front of the backlight source  8 , the reflection film  9  being composed of PET or the like curved to a U-shape with its front side opened and having a surface subjected reflection processing. 
     The above respective components are held by being clamped by an upper holder  10  and a lower holder  11  as a frame member. 
     The direct light from the backlight source  8  and the reflected light resulting from the direct light reflected at the reflection film  9  enter the light transmission member  5  from the end surface  5   a  thereof disposed in front of the backlight source  8 . The incoming light can travel to every point in the light transmission member  5  while irregularly reflecting in the light transmission member  5 . Further, the incoming light in the irregularly reflecting state is reflected upward in a vertical direction with respect to the surface direction of the light transmission member  5  at the light transmission member reflection pattern  5   b  on the bottom surface of the light transmission member  5  and the reflection sheet  6  under the light transmission member  5  and emerges upward from the upper surface of the light transmission member  5 . 
     Since the reflection sheet  6  has nothing for partly absorbing the light, the reflected light reflected at the reflection sheet  6  of the present invention can cause the light having a large quantity of light and a high degree of brightness to emerge upwardly of the light transmission member  5 . 
     The bright light emerged from the light transmission member  5  is diffused by the diffusion plate  4  and the thus diffused light is collected to the visual field angle of an effective display area  1   a  by the lens sheets  3 , passes through the protection/diffusion sheet  2  on the lens sheets  3  and uniformly irradiates the entire region of the effective display area  1   a  of the liquid crystal panel  1  from the backside thereof without unevenness. 
     As shown in FIG. 3, since the diffusion plate  4  has the light quantity control portion  4   a  formed on the one surface thereof which is not subjected to the glaring prevention on the end  4   b  side located near to the backlight source  8 , the light quantity control portion  4   a  being formed by print or the like to a dot pattern which is composed of a white material having a light transmitting property to a certain extent, a part of the light from the backlight source  8  passes through the light quantity control portion  4   a  and emerges to the lens sheets  3  on the light quantity control portion  4   a  and the remaining light reflects at the light quantity control portion  4   a  and makes irregular reflection in the light transmission member  5 . 
     As shown in FIG. 3, the dots of the light quantity control portion  4   a  located on the end  4   b  side near to the backlight source  8  are set to a large size, for example, to an outside diameter of about 0.5 mm and the dots farthest from the backlight source  8  are set to an outside diameter of about 0.1 mm so that the dots have a gradually reducing size as they are apart from the backlight source  8 . 
     The light quantity control portion  4   a  is formed within the range of a size B from the end  4   b  of the diffusion plate  4 , for example, within 10 mm therefrom so that it corresponds to the position where emission lines  1   c  generate to the effective display area  1   a.    
     The liquid crystal display device of the present invention described above is provided with the light transmission member reflection pattern  5   b  formed on the bottom surface of the light transmission member  5  as well as the light quantity control portion  4   a  formed on the one surface of the diffusion plate  4  which is not subjected to the glaring prevention processing on the end  4   b  side thereof which is located near to the backlight source  8  in order to eliminate the emission lines  1   c  having “glaring” which is partially stronger toward the position near to the edge portion  1   b  of the liquid crystal panel  1  than at the portion of the effective display area  1   a  which is located apart from the edge portion  1   b,  the emission lines  1   c  being caused by the composite light beam composed of the first light beam which is reflected at the reflection, sheet  6  in the approximately vertical direction and the second light beam which irradiates the portion of the liquid crystal panel  1  near to the edge portion  1   b  thereof and the second light beam being the oblique light beam A shown by the arrow in FIG. 1 which enters the light transmission member  5  from the backlight source  8  and the reflection film  9  in addition to the first light beam, passes through the light transmission member  5  straight in an oblique upward direction without making irregular reflection in the light transmission member  5  and emerges therefrom. Since a portion of the composite light beam composed of the first light beam and the second light beam passes through the light quantity control portion  4   a,  the light beam without “glaring” irradiates the portion of the effective display area  1   a  near to the edge portion  1   b.    
     The remaining light beam which has not passed through the light quantity control portion  4   a  is reflected at the light quantity control portion  4   a  downward by making irregular reflection in the light transmission member  5  likewise the first light beam, and combined with the first light beam and emerges from the upper surface of the light transmission member  5  externally upward by being reflected at the reflection sheet  6  upward. 
     At the time, since the size of the dots forming the light quantity control portion  4   a  is increased toward the end  4   b  near to the backlight source  8  and gradually reduced as the light quantity control portion  4   a  is apart from the backlight source  8  as described above, the “glittering state” emission lines  31   c  at the position near to the edge portion  1   b  of the liquid crystal panel  1  are eliminated. As a result, the brightness of irradiation at the portion of the effective display area  1   a  near to the edge portion  1   b  of the liquid crystal panel  1  is made equal to the brightness of the portion of the effective display area  1   a  apart from the edge portion  1   b  as well as the effective display area  1   a  which is bright as a whole can be obtained. 
     Note, the present invention is not limited to the arrangement that the backlight source  8  composed of the cold cathode fluorescent lamp or the like is disposed on the one end surface side of the light transmission member  5  but is also applicable to the arrangement that the backlight sources  8  are disposed on both the end surface sides of the light transmission member  5  in confrontation with each other. 
     Next, a liquid crystal display device of a second embodiment according to the present invention will be described. As shown in FIG. 4, the liquid crystal display device is arranged such that a light transmitting protection/diffusion sheet  2  is disposed on the back surface side of a liquid crystal panel  1  so as to diffuse light and protect the surface of lens sheets  3  disposed under the protection/diffusion sheet  2 . The lens sheets  3  have a light transmitting property and are composed of two similar lens sheets laminated to each other with the upper surface thereof arranged as a prism surface for improving the brightness of light. A diffusion plate  14  disposed under the two lens sheets  3  is composed of a film such as PET (polyethylene terephthalate) or the like, one surface of the film being subjected to frosted-glass-like glaring prevention processing and having fine uneven portions formed thereto. The protection/diffusion sheet  2 , the lens sheets  3  and the diffusion plate  14  are disposed by being laminated to each other with their surfaces in intimate contact with each other. 
     A light transmission member  15  which is made by molding an acrylic resin or the like having a high degree of transmittance to a sheet shape is disposed below the diffusion plate  14  to irregularly reflect the light entered to it from a side  15   a  thereof. 
     Successively laminated under the light transmission member  15  are a light transmission member reflection pattern  15   b  formed on the bottom surface of the light transmission member  15  and a reflection sheet  16  for reflecting the light irregularly reflected in the light transmission member  15  upward in an approximately vertical direction and causing the reflected right to emerge from the upper surface of the light transmission member  15  externally. The end surface  15   a  of the light transmission member  15  and the end surface  16   a  of the reflection sheet  16  are located on the same plane in a vertical direction and laminated, respectively. 
     As shown in FIG. 6 to FIG. 8, a light quantity control portion  16   b  is formed to the reflection sheet  16  within the range of 10 mm (size Y) from the end surface  16   a  thereof. The light quantity control portion  16   b  is made of a light absorbing color such as, for example, black, gray or the like formed to a dot pattern shape as shown in FIG. 6 by print or the like. The light quantity control portion  16   b  may be formed to an overall-printed pattern as shown in FIG.  7 . Alternatively, the overall-printed pattern may be formed to the portion of the light quantity control portion  16   b  near to the end surface  16   a  thereof and the dot-pattern- shaped light quantity control portion  16   b  may be formed within the range within 10 mm (size Y) from the end surface  16   a  in proximity to the overall-printed pattern as shown in FIG.  8 . With the above arrangement, the light irradiated from the backlight source  8  to the light quantity control portion  16   b  is absorbed by it and prevented from being reflected upward. 
     As shown in FIG. 4, a cylindrical backlight source  8  composed of a cold cathode fluorescent lamp (CCFL) or the like is disposed on the end surface  15   a  side of the light transmission member  15  and a reflector  19  which is made by molding a plastic material such as white polycarbonate or the like having a good light reflection efficiency is disposed around the backlight source  8  so as to encase it. 
     A U-shaped opening  19   a  is formed to the reflector  19  on the side thereof confronting the end surface  15   a  of the light transmission member  15  and the backlight source  8  is encased in the opening  19   a.    
     A reflection surface  19   b  to which glossy processing is applied when it is molded is formed to the inner surface of the opening  19   a  to improve the reflection efficiency of the light irradiated from the backlight source  8 . 
     The reflection surface  19   b  located on the lower side of the U-shaped opening  19   a  of the reflector  19  is extended to the other side to thereby form a case portion  19   c  on which the respective components such as the reflection sheet  16  and the like are placed integrally with the reflection surface  19   b.  The above glossy processing is not applied to the case portion  19   c.    
     As shown in FIG. 4, a light quantity control portion  19   e  similar to the light quantity control portion  16   b  of the reflection sheet  16  is formed to an overall-printed state of black, gray or the like or/and to a dot state by print or the like on the lower flat portion  19   d  of the reflection surface  19   b  in connection to the end surface  16   a  of the reflection sheet  16  placed on the case portion  19   c.    
     The light quantity control portion  19   e  of the reflection surface  19   b  is formed within the range from the end surface  16   a  of the reflection sheet  16  which is on the same plane as that of the end surface  15   a  of the light transmission member  15  to just below the backlight source  8 . That is, it is formed in the range from the portion where a tangential line X which extends vertically downward from the outer periphery of the cold cathode fluorescent lamp or the like constituting the backlight source  8  is across the lower flat portion  19   d  to the outermost potion of the opening  19   a.    
     The above respective components are held by being clamped by the reflector  19  having the case portion  19   c  and an upper holder  10  as a frame member. 
     The light emerged from the backlight source  8  includes a light beam traveling straight in a horizontal direction and oblique light beams obliquely entering the end surface  15   a  of the light transmission member  15  and the above horizontally traveling light beam enters the light transmission member  5  from the end surface  15   a  thereof and can travel to every point in the light transmission member  15  while irregularly reflecting therein. 
     The above incoming light beam in the irregularly reflecting state is reflected at the reflection sheet  16  under the light transmission member  15  upward in a vertical direction with respect to the surface direction of the light transmission member  15  and emerges from the upper surface of the light transmission member  15  upward. At the time, the light beam resulting from the irregularly reflected light beam in the light transmission member  5  which was reflected at the reflection sheet  16  also emerges externally upward from the upper surface of the portion of the light transmission member  15  on the side of the other end surface (not shown) thereof which confronts the end surface  15   a  of the light transmission member  15  in an approximately uniform degree of brightness. 
     The light emerged from the light transmission member  15  is diffused by the diffusion plate  14 , the thus diffused light is collected to the visual field angle of an effective display area  1   a  by the lens sheets  3 , passes through the protection/diffusion sheet  2  on the lens sheets  3  and uniformly irradiates the entire region of the effective display area  1   a  of the liquid crystal panel  1  from the backside thereof without unevenness as the conventional first light beam. 
     Although the oblique light beam A emerged from the backlight source  8  shown in FIG. 4 irradiates the light quantity control portion  16   b  and the oblique light beam B emerged therefrom irradiates the light quantity control portion  19   e,  respectively, since the oblique light beams A and B are absorbed by the light quantity control portions  16   b  and  19   e,  they are not reflected upward. 
     As a result, the emission lines  31   c  which are conventionally generated in the vicinity of the edge portion  1   b  of the effective display area  1   a  of the conventional liquid crystal panel  1  are not generated. 
     Since an oblique light beam a which reaches a position far from the light quantity control portion  16   b  of the reflection sheet  16  has a small incident angle α, the reflected light beam al thereof also has a small reflecting angle β likewise the incident angle α. Accordingly, the reflected light beam a 1  is irregularly reflected in the light transmission member  15  and combined with the first light beam and can uniformly irradiate the entire region of the effective display area  1   a  of the liquid crystal panel  1  from the backside thereof without unevenness. 
     As a modification of the embodiment  2 , when a reflection sheet  20  to which a light quantity control portion  20   b  is formed is extended from the end surface  15   a  of the light transmission member  15  to the outside thereof on the backlight source  8  side, a light quantity control portion  20   c  is also formed on the extended portion of the reflection sheet  20  and the extended portion of the reflection sheet  20  on which the light quantity control portion  20   c  is formed is laid on the lower flat portion  19   d  of the reflection surface  19   b  of the reflector  19  as shown in FIG. 5, since the oblique light beams A and B irradiated from the backlight source  8  are absorbed by the light quantity control portions  20   b  and  20   c,  the emission lines  31   c  described in the above conventional art are not generated. As a result, the entire region of the effective display area  1   a  of the liquid crystal panel  1  can be uniformly irradiated from the backside thereof without unevenness. 
     The reflection sheet  20  including the light quantity control portion  20   c  which extends externally from the end surface  15   a  of the light transmission member  15  is formed in the range from end surface  15   a  of the light transmission member  15  to just below the backlight source  8 . That is, the reflection sheet  20  is extended from the portion where the tangential line X which extends vertically downward from the outer periphery of the cold cathode fluorescent lamp or the like constituting the backlight source  8  is across the lower flat portion  19   d  to the outermost potion of the opening  19   a.    
     Note, the present invention is not limited to the arrangement that the backlight source  8  composed of the cold cathode fluorescent lamp or the like is disposed on the one end surface side of the light transmission member  5  but is also applicable to the arrangement that the backlight sources  8  are disposed on both the end surface sides of the light transmission member  5  in confrontation with each other. 
     Next, a third embodiment of a liquid crystal display device according to the present invention will be described. As shown in FIG. 9, the liquid crystal display device is arranged such that a light transmitting protection/diffusion sheet  2  is disposed on the back surface side of a liquid crystal panel  1  so as to diffuse light and protect the surface of lens sheets  3  disposed under the protection/diffusion sheet  2 . The lens sheets  3  have a light transmitting property and are composed of two similar lens sheets laminated to each other with the upper surface thereof arranged as a prism surface for improving the brightness of light. A diffusion plate  14  disposed under the two lens sheets  3  is composed of a film such as PET (polyethylene terephthalate) or the like, one surface of the film being subjected to frosted-glass-like glaring prevention processing and having fine uneven portions formed thereto. The protection/diffusion sheet  2 , the lens sheets  3  and the diffusion plate  14  are disposed by being laminated to each other with their surfaces in intimate contact with each other. 
     Successively laminated under the diffusion plate  24  are a light transmission member  25  disposed below the diffusion plate  24  which is made by molding an acrylic resin or the like having a high degree of transmittance to a sheet shape for irregularly reflecting light entered to it from the end surface thereof, a light transmission member reflection pattern  25   c  disposed on the bottom surface of the light transmission member  25  and a reflection sheet  26  disposed under the light transmission member  25  for reflecting the light irregularly reflected in the light transmission member  25  upward in an approximately vertical direction and causing the reflected right to emerge externally upward from the light transmission member  25 . 
     A reflector T made by molding a plastic material such as white polycarbonate or the like is disposed to the end surface  25   a  side of the light transmission member  25 . The reflector T includes an encasing portion T 1  which encases a backlight source  8  composed of a cold cathode fluorescent lamp (CCFL) or the like and disposed at the center thereof and an opening T 2  which is formed to the side thereof in proximity to the end surface  25   a  of the light transmission member  25  and continuous to the encasing portion T 1 , the size of the opening T 2  being made narrower than the vertical width of the encasing portion T 1 . 
     Since the reflector T is divided into two portions, that is, an upper reflector  29  and a lower reflector  30  and formed by molding or the like, the encasing portion T 1  and the opening T 2  can be easily processed. 
     The reflector T is formed as a single member by combining the divided upper and lower reflectors  29  and  30 , reflection walls  29   a  and  30   a  are formed to a semi-circular shape around the inner periphery of the encasing portion T 1  concentrically with the backlight source  8  and glossy processing is applied to the respective reflection walls  29   a,    30   a  to improve the reflecting efficiency thereof. 
     Light direction control walls  29   b,    30   b  are formed to the opening T 2  of the reflector T to control the direction of the light from the backlight source  8 . Since the light direction control walls  29   b,    30   b  are formed by projecting the upper and lower ends of the opening T 2  to control the direction of the light irradiated to the end surface  25   a  of the light transmission member  25  to prevent the oblique light beams A, B from the backlight source  8  from emerging directly outward, the generation of the emission lines  31   c  can be prevented because the aforesaid second light beam of the prior art does not reach the range within 10 mm from the edge portion  1   b  of the liquid crystal panel  1 . 
     As shown in the enlarged view of the main portion of FIG. 11, curved reflection layers  29   c,    30   c  composed of a reflection material having a high reflection efficiency which is different from the material of the reflection walls  29   a,    30   a  are formed to the light direction control walls  29   b,    30   b  on the encasing portion T 1  side thereof. 
     The reflection material having the high reflection efficiency which forms the reflection layers  29   c,    30   c  is mirror finished by being subjected to vapor deposition of a metal such as, for example, silver or the like or coated with a white paint or the like. 
     Since the size Y of the opening T 2  where the light direction control walls  29   b,    30   b  are formed is set to 50-95% of the thickness X of the light transmission member  5 , the light from the backlight source  8  is not irradiated to the upper and lower corners  25   b  of the end surface  25   a  of the light transmission member  25 . As a result, since the direct light from the backlight source  8  is irregularly reflected in the light transmission member  25  and reaches the other end surface (not shown) side of the light transmission member  25  which is apart from the end surface  25   a  thereof, the brightness at the other end surface is not almost changed even if it is apart from the backlight source  8  although the quantity of light at the portion near to the end surface  25   a  from the backlight source  8  is reduced. 
     As a result, since the brightness of the light beam emerged upward of the upper surface of the light transmission member  5  from the end surface  25   a  of the light conductor  35  is the same as the brightness of the light beam emerged upward of the upper surface of the light transmission member  25  from the other end surface (not shown) which is apart from the end surface  25   a,  the effective display area  1   a  of the liquid crystal panel  1  can be uniformly irradiated and the generation of the emission lines  31   c  can be prevented. 
     The above respective components are held by being clamped by the lower reflector  30  having the case portion  30   d  and an upper holder  12  as a frame member. 
     The light emerged from the backlight source  8  emerges from the opening T 2  and enters the light transmission member  25  from the end surface  25   a  thereof. The incoming light can travel to every point in the light transmission member  25  while irregularly reflecting in the light transmission member  25 . Further, the incoming light in the irregularly reflecting state is reflected upward in a vertical direction with respect to the surface direction of the light transmission member  25  at the light transmission member reflection pattern  25   c  on the bottom surface of the light transmission member  25  and the reflection sheet  26  under the light transmission member  25  and emerges upward from the upper surface of the light transmission member  25 . 
     At the time, the light beam resulting from the irregularly reflected light beam in the light transmission member  25  which was reflected at the light transmission member reflection pattern  25   c  and the reflection sheet  26  also emerges externally upward from the upper surface of the portion of the light transmission member  25  on the side of the other end surface (not shown) thereof which confronts the end surface  15   a  of the light transmission member  25 . 
     The light emerged from the light transmission member  25  is diffused by the diffusion plate  24 , the thus diffused light is collected to the visual field angle of the effective display area  1   a  by the lens sheets  3 , passes through the protection/diffusion sheet  2  on the lens sheets  3  and uniformly irradiates the entire region of the effective display area  1   a  of the liquid crystal panel  1  from the backside thereof without unevenness. 
     Since the light direction control walls  29   b,    30   b  are disposed to the upper and lower sides of the opening T 2  of the reflector T in the liquid crystal display device of the present invention described above, the oblique light beams A and B having a small inclining angle to the end surface  25   a  of the light transmission member  25  are shaded by the light direction control walls  29   b,    30   b  and are not caused to directly emerge externally of the reflector T. As a result, the emission lines  31   c  which are conventionally generated within the range of 10 mm from the edge portion  1   b  can be prevented. 
     Since the oblique light beams A 1  and B 1  having a large inclining angle to the end surface  25   a  which emerge from the opening T 2  and enter the light transmission member  25  are irregularly reflected at a position apart from the end surface  25   a  and emerge upward of the light transmission member  25 , they are combined with the first light beam described in the prior art and can irradiate the entire surface of the effective display area  1   a  of the liquid crystal panel  1  with uniform brightness. 
     Since the size Y of the opening T 2  is set to 50-95% of the thickness X of the light transmission member  25 , the oblique light beams A and B from the backlight source  8  do not enter the upper and lower corners  25   b  of the end surface  25   a  of the light transmission member  25 . As a result, since no “glaring state” emission lines  31   c  are generated to a position near to the edge portion  1   b  of the liquid crystal panel  1 , the irradiation at the portion of the effective display area  1   a  within 10 mm from the edge portion  1   b  of the liquid crystal panel  1  is as bright as that of the portion of the effective display area  1   a  apart 10 mm or more from the edge portion  1   b,  whereby the effective display area  1   a  having uniform brightness can be obtained. 
     Even if the quantity of light from the backlight source  8  is reduced by the light direction control walls  29   b,    30   b  of the reflector T, since the mirror-finished reflection layers  29   c,    30   c  are formed to the curved insides of the light direction control walls  29   b,    30   b,  the oblique light beams A and B shaded by the light direction control walls  29   b,    30   b  are reflected at the reflection layers  29   c,    30   c  toward the encasing portion T 1 . 
     Since the reflected light beams impinge on the reflection walls  29   a,    30   a  and are reflected thereat in the direction of the opening T 2 , the quantity of light emerged externally from the opening T 2  is composed of the quantity of the oblique light beams A and B from the reflection layers  29   c,    30   c  of the light direction control walls  29   b,    30   b  in addition to the quantity of the conventional direct light from the backlight source  8  and the quantity of the conventional reflected light from the reflection layers  29   c,    30   c.  Thus, even if the brightness of the backlight source  8  is the same as the conventional brightness, the light beam emerged externally from the opening T 2  can be made more bright than the conventional light beam. 
     Accordingly, the entire region of the effective display area  1   a  of the liquid crystal panel  1  can be brightly and uniformly irradiated from the backside thereof by the light of high brightness without unevenness. 
     Note, the present invention is not limited to the arrangement that the backlight source  8  composed of the cold cathode fluorescent lamp or the like is disposed on the one end surface side of the light transmission member  5  but is also applicable to the arrangement that the backlight sources  8  are disposed on both the end surface sides of the light transmission member  5  in confrontation with each other. 
     As described above, since the liquid crystal display device of the present invention forms the light quantity control portion to the dot shape on at least one side of the diffusion plate which is located near to the backlight, the light from the backlight source is not absorbed by a portion of the reflection sheet. As a result, since all the light from the backlight source emerges from the light transmission member, the light of high brightness which is about  20 % brighter than conventional light can be caused to pass through the diffusion plate to which the light quantity control portion is formed to the dot shape, whereby the entire surface of the effective display area  1   a  of the liquid crystal panel  1  can be uniformly and brightly irradiated from the backside thereof without emission lines and unevenness. 
     Since the size of the dots of the dot pattern of the light quantity control portion is increased toward the backlight source and gradually reduced as the light quantity control portion is apart from the backlight source, the light of high brightness which has the largest quantity of light and is located near to the backlight source is reduced by the pattern having the large dots and the size of the dot pattern is gradually reduced in proportion to that the quantity of light is gradually reduced up to the position about 10 mm apart from the edge portion  1   b  of the effective display area  1   a,  the light emerged from the diffusion plate provided with the light quantity control portion can achieve the uniform and bright irradiation without unevenness. 
     Since the diffusion plate has the one surface to which no glaring prevention processing is applied and the other surface to which the glaring prevention processing is applied and the light quantity control portion is formed to the one surface which is not subjected to the glaring prevention processing, the dot pattern as the light quantity control portion is formed by print or the like on the smooth surface which is not subjected to the glaring prevention processing. As a result, the dot pattern is strongly secured to the smooth surface and not exfoliated therefrom while the diffusion plate is handled. 
     Since the liquid crystal display device of the present invention forms the light quantity control portion to the reflection sheet on the side thereof near to the backlight source and the light quantity control portion to the reflection surface of the reflector on the side thereof which is in contact with the reflection sheet in the fashion that the former light quantity control portion is continuous to the latter light quantity control portion and the light quantity control portion formed to the reflection surface of the reflector covers the range from the end surface of the light transmission member to just below the backlight source, the oblique light beams from the backlight source are absorbed by the light quantity control portions, whereby the effective display area can be uniformly irradiated without emission lines and unevenness. 
     The reflection sheet is extended from the end surface of the light transmission member to the outside thereof on the side of the backlight source and the light quantity control portion is formed to the portion of the reflection sheet which is near to the end surface of the light transmission member and to the extended portion of the reflection surface and the extended portion of the reflection sheet to which the light quantity control portion is formed is laid on the reflection surface of the reflector so that the light quantity control portion disposed on the reflection surface of the reflector covers the range from the end surface of the light transmission member to just below the backlight source. As a result, since the generation of the emission lines in the effective display area can be prevented by the formation of the light quantity control portion only to the reflection sheet side without forming it to the reflector side, it is simple to print the light quantity control portion to the overall-printed state or the dot pattern state, whereby the liquid crystal display device without the emission lines can be provided at a low cost. 
     Since the light quantity control portion is formed to the overall-printed state or the dot pattern state, the size of the dots and the density of the overall print can be changed in correspondence to the brightness of the edge portion  1   b  of the effective display area  1   a  of the liquid crystal panel  1  by changing a print screen for printing the light quantity control portion, whereby the liquid crystal display device having optimum brightness without emission lines can be provided in correspondence to various types of products. 
     Since the liquid crystal display device of the present invention forms the light direction control walls to the opening of the reflector to control the direction of the light from the backlight source and the light direction control walls project from the upper and lower portions of the opening, the oblique light beams from the backlight source can be shaded by the light direction control walls of the single structure, whereby the entire surface of the effective display area of  1   a  the liquid crystal panel  1  can be uniformly irradiated from the backside thereof without emission lines and unevenness. 
     Since the size of the opening of the light direction control walls is set to 50-95% of the thickness of the light transmission member, the uniform irradiation without emission lines and unevenness can be secured to the portion of the effective display area  1   a  of the liquid crystal panel near to the edge portion  1   b.  As a result, when parts whose opening size is changed in accordance with various types of products, there can be provided the liquid crystal display device in which the brightness of irradiation of the liquid crystal panel is not dispersed even if a type of a product is changed. 
     Further, since the reflection layers composed of the material different from that of the reflection walls are formed to the insides of the light direction control walls, the oblique light beams emerged from the backlight source are reflected at the reflection layers toward the encasing portion, reflected at the periphery of the encasing portion and emerge from the opening to the light transmission member together with the direct light from the backlight source, the entire surface of the effective display area  1   a  of the liquid crystal panel  1  can be brightly and uniformly irradiated from the backside thereof without emission lines and unevenness.