Abstract:
A display device capable of minimizing the width of a bezel is presented. The display device includes a display panel displaying an image; a first frame having a first surface configured to support the display panel and a second surface on which a first coupling mechanism is formed; a second frame having a second coupling mechanism and engaged with the first frame; an optical member interposed between the first frame and the second frame; a receptacle including four side-wall parts and a bezel part extended from the side-wall parts to an inside thereof, and receiving the display panel, the first frame, and the second frame therein, wherein the first coupling mechanism and the second coupling mechanism comprise a first fixing projections and a first fixing holes into which the first fixing projections are inserted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority from Korean Patent Application No. 10-2009-0005673 filed on Jan. 22, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Technical Field 
     Embodiments of the present invention generally relate to a display device and, more particularly, to a display device having a structure that may minimizes the width of a bezel part so that a plurality of display devices may be connected together to constitute a multi-display device. 
     2. Related Art 
     With the development of modern society as an information society, large-sized and thin display devices are in demand in the market. Since conventional CRT devices cannot fully satisfy such demand, calls for flat display devices represented, for example, by a plasma display panel (PDP), a plasma address liquid crystal display panel (PALC display panel), a liquid crystal display (LCD), and an organic light emitting diode (OLED), and the like, are explosively increasing. 
     The liquid crystal display (LCD) is a display device having advantages, for example, of low power consumption and small size, and has been widely used, for example, in the computer industry, electronic industry, and information &amp; communications industry. The liquid crystal display typically includes a liquid crystal panel assembly provided with a liquid crystal panel for displaying image information, a backlight assembly provided with a light emitting device and a light guide plate guiding emitted light toward the liquid crystal panel, and a receptacle receiving the liquid crystal panel assembly and the backlight assembly therein. 
     Recently, with the demand for a large-screen liquid crystal display, there has been an increasing interest in a multiple liquid crystal display having a plurality of liquid crystal display units joined together. 
     A multi-display device provides a large display screen by joining a plurality of display devices in the form of a matrix. With the typical multi-display device, non-display areas are formed on the screen due to the receptacles of the respective display devices. The non-display areas formed on the screen may distort an image being displayed on the screen, and may detract from viewing pleasure. Accordingly, in order to reduce the non-display areas on the screen, a structure that can minimize the bezel area of the display device is sought. 
     Accordingly, there is a need for a structure to minimize the width of a bezel area of a display device and, as a receptacle forming a frame of the display device, to maintain stiffness. 
     SUMMARY 
     Accordingly, embodiments of the present invention have been made to solve the above-mentioned problems occurring in the prior art, and embodiments of the present invention may provide a display device having a structure that minimizes (e.g., reduces) the width of a bezel part so that a plurality of display devices may be connected together to constitute a multi-display device. 
     Additional advantages, objects, and features of embodiments of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. 
     In one or more embodiments of the present invention, there is provided a display device, which includes a display panel that displays an image; a first frame having an upper surface on which the display panel is seated and a lower surface including first fixing projections; and a second frame engaged with the first frame and including fixing holes into which the first fixing projections are inserted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features, and advantages of embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a display device according to a first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the display device of  FIG. 1  in accordance with an embodiment; 
         FIG. 3  is a partial exploded perspective view explaining engagement of a first frame and a second frame included in the display device of  FIG. 1  in accordance with an embodiment; 
         FIG. 4  is a partial perspective view of the display device of  FIG. 1  in accordance with an embodiment; 
         FIG. 5  is a sectional view of the display device, taken along line V-V′ in  FIG. 4  in accordance with an embodiment; 
         FIG. 6  is an enlarged sectional view of area “A” in  FIG. 5  in accordance with an embodiment; 
         FIG. 7  is a partial perspective view of a display device according to a second embodiment of the present invention; 
         FIG. 8  is a partial exploded perspective view explaining engagement of a first frame and a second frame included in the display device of  FIG. 7  in accordance with an embodiment; 
         FIG. 9  is a sectional view of the display device, taken along line IX-IX′ in  FIG. 7  in accordance with an embodiment; 
         FIG. 10  is a partial perspective view of a display device according to a third embodiment of the present invention; 
         FIG. 11  is a partial exploded perspective view explaining engagement of a first frame and a second frame included in the display device of  FIG. 10  in accordance with an embodiment; 
         FIG. 12  is a sectional view of the display device, taken along line XII-XII′ in  FIG. 10 ; and 
         FIG. 13  is a perspective view of a multi-display device according to an embodiment of the present invention including display devices according to one or more embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The aspects and features of embodiments of the present invention and methods for achieving the aspects and features will be apparent by referring to the embodiments to be described in detail with reference to the accompanying drawings. The present invention is not limited, however, to the embodiments disclosed hereinafter, but can be implemented in diverse forms. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is only defined within the scope of the appended claims. In the entire description of embodiments of the present invention, the same drawing reference numerals are used for the same elements across various figures. 
     Spatially relative wordings “below”, “beneath”, “lower”, “above”, “upper”, and so forth, as illustrated in the drawings, may be used to facilitate the description of relationships between an element or constituent elements and another element or other constituent elements. The spatially relative wordings should be understood as wordings that include different directions of the element in use or operation in addition to the direction illustrated in the drawings. 
     Hereinafter, with reference to  FIGS. 1 and 2 , a display device according to a first embodiment of the present invention will be described in detail.  FIG. 1  is a perspective view of a display device according to a first embodiment of the present invention, and  FIG. 2  is an exploded perspective view of the display device of  FIG. 1  in accordance with an embodiment. 
     A display device  1  according to the first embodiment of the present invention includes a display panel  20  to display an image, and a backlight assembly to provide light to the display panel  20 . The display panel  20  and the backlight assembly are received in an upper receptacle  10  and a lower receptacle  80 . In the center part of the upper receptacle  10 , an open window for exposing the display panel  20  therethrough is formed. The upper receptacle  10  is formed to increase the exposed area of the display panel  20  to a maximum while maintaining the stiffness enough to maintain the frame of the display device  1 . Hereinafter, the structure of the display device  1  will be described in detail. 
     The display panel  20  serves to display an image, and includes a lower substrate  21 , an upper substrate  22 , and a liquid crystal layer (not illustrated) interposed between the two substrates  21  and  22 . The lower substrate  21  may include gate lines (not illustrated), data lines (not illustrated), a thin film transistor array, and pixel electrodes, for example, and the upper substrate  22  may include color filters, black matrices, and common electrodes, for example. The color filters and the common electrodes, for example, may be formed on the lower substrate  21 . 
     In the following description of an embodiment of the present invention, a liquid crystal panel including a liquid crystal layer will be described as a concrete example of the display panel  20 . However, the display panel  20  is not limited thereto, and has a structure that may be used in all display devices using a flat type display panel  20 . That is, the display device described in the description has a structure that may reduce the non-display area of the display device and extend the display area by sufficiently maintaining the stiffness of the display device. By using this structure, the valid screen (e.g., image-displaying portion of the screen) is increased, and the construction of the multi-display device is facilitated as well. The construction of the display device according to an embodiment of the present invention will be described later. 
     Referring to  FIG. 2 , components of the display device  1  will be described in detail. The upper receptacle  10  forms an external appearance of the display device  1 , and has a space formed therein to receive the display panel  20 . In the center part of the upper receptacle  10 , an open window for exposing the display panel  20  to an outside of the upper receptacle  10  is formed. The upper receptacle  10  includes four side-wall parts  11  formed on sides thereof, and a bezel part  12  extended from the four side-wall parts to the inside of the receptacle. The thicknesses of the four side-wall parts and the bezel part  12  of the upper receptacle greatly affect the size of the display device  1 , and thus it is preferable to make them as small as possible. On the other hand, the side-wall parts  11  and the bezel part  12  are important parts in maintaining the whole stiffness of the display device  1 , and thus it is required for the parts to maintain sufficient stiffness. The shapes of the side-wall part  11  and the bezel part  12  will be described later. 
     The upper receptacle  10  is engaged with the lower receptacle  80 , and the display panel  20 , an optical sheet  40 , a diffusion plate  50 , and light sources  70  are accommodated between the upper receptacle  10  and the lower receptacle  80 . In order to support the accommodation of the display panel  20 , the optical sheet  40 , and the diffusion plate  50 , the display device may further include a first frame  30  and a second frame  60 . The structure including, for example, the optical sheet  40 , the diffusion plate  50 , and the light sources  70  may be called a backlight assembly. In other words, the backlight assembly may refer to components that provide light to the display panel  20  in the form of surface light sources. 
     The display device according to an embodiment of the present invention includes a direct downward type backlight assembly in which the light sources  70  are positioned on the direct downward surface of the display panel  20 . The light source may be in the form of a line light source, such as a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), or an external electrode fluorescent lamp (EEFL). 
     Lamps may be successively arranged at predetermined intervals, and may be of a direct downward type. In order to obtain uniform luminance by making the distribution of discharge gas in the lamp uniform, it is preferable that the lamps are arranged in a horizontal direction against the display panel  20 . At an end of the lamp, a socket  71  (see  FIG. 5 ) for supporting and fixing the lamp and providing a lamp driving voltage to the lamp is formed. 
     As the light source  70 , not only a fluorescent lamp in the form of a line light source but also a light emitting diode (LED) in the form of a point light source may be used. The light emitting diodes may be successively arranged at predetermined intervals on a printed circuit board. Since the light emitting diode has a structure that has a high luminance and is small-sized in comparison to the fluorescent lamp, the light emitting diode may be advantageous in fabricating an ultra slim display device. Light emitting diodes emit red light, green light, and blue light, respectively, to heighten the color purity, and thus a high-quality image may be obtained through the display device. Also, since the red light, the green light, and the blue light can be respectively controlled, it is easy to adjust the color temperature of the light source, and thus a display device capable of presenting color more plenteously may be implemented. 
     According to the display device  1  including the direct downward type backlight assembly according to embodiments of the present invention, the light sources  70  are uniformly distributed on the bottom surface of the lower receptacle  80 , and the diffusion plate  50  is arranged just on the light sources  70 . The diffusion plate  50  serves to diffuse light incident from the light sources  70 , and to provide light having uniform luminance to the display panel  20 . More specifically, the light sources  70  are distributed in the form of line light sources or point light sources, and emit light having non-uniform luminance on the basis of the whole surface overlapping the display panel  20 . Specifically, the light luminance is high around the light source  70 , and the light luminance is low in a space between the light sources  70 , so that the luminance becomes non-uniform. The diffusion plate  50  diffuses the non-uniform light in diverse directions to reduce the non-uniformity of the luminance. 
     The diffusion plate  50  may be formed as a light-transparent resin layer to which diffuser is added. The diffuser may include any or all of, for example, a silicon diffuser, a magnesium diffuser, or calcium oxide, and the like. The light-transparent resin layer may include, for example, any or all of poly methyl methacrylate (PMMA), methyl styrene (MS), poly styrene (PS), or poly carbonate (PC), and the like. 
     The optical sheet  40  is arranged on the upper part of the diffusion plate  50 , and serves to diffuse and condense light being transferred from the light sources  70 . The optical sheet  40  may include, for example, any or all of a diffusion sheet, a first prism sheet, or a second prism sheet, and the like. The diffusion sheet is positioned on an upper part of the light sources  70 , and serves to improve the luminance uniformity of light incident from the light sources  70 . The first prism sheet is positioned on the upper part of the diffusion sheet, and on one surface of the first prism sheet, triangular prism shaped prism patterns (not illustrated) for condensing and emitting light diffused by the diffusion sheet are formed with specified arrangement. The second prism sheet is a multilayer-structured reflective polarization prism sheet positioned on the upper part of the prism sheet to condense and polarize the light. However, if the luminance and the viewing angle can be sufficiently secured with the first prism sheet, the second prism sheet may be excluded. The optical sheet  40  may be changed in diverse form in accordance with the specification of the backlight assembly. 
     The optical sheet  40  may include one or more of a diffusion sheet, a prism sheet, and a protection sheet, and have a composite function thereof. That is, the lower part of the optical sheet  40  is formed to have a diffusion function, the upper part thereof has a prism pattern (not illustrated) formed thereon, and a protection layer (not illustrated) is formed on the prism pattern. Since the optical sheet  40  has all functions including the diffusion function and the prism function, the number of components of the display device may be reduced to implement a slim display device. 
     The diffusion plate  50  and the optical sheet  40  are fixed to the first frame  30  and the second frame  60 , respectively, and are received in the upper receptacle  10  and the lower receptacle  80 . The first frame  30  and the second frame  60  form seating surfaces of the display panel  20 , safely receive the diffusion plate  50  and the optical sheet  40 , and reinforce the stiffness of the display device  1 . The structure of the first frame  30  and the second frame  60  will be described in more detail later. The components having optical functions, such as the optical sheet  40  and the diffusion plate  50  are called optical members. 
     A reflection sheet  75  is installed on the lower part of the light sources  70  to reflect the light emitted from the light sources  70  to an upper part of the light sources  70 . The reflection sheet  75  may be made of a material which has a good elasticity and superior reflectivity, and is of a thin type. For example, the reflection sheet  75  may be made of polyethylene terephtalate (PET). Also, the reflection sheet  75  may be formed by coating a reflection film for heightening the light reflectivity of the thin type material having a good elasticity. Also, the reflection sheet  75  may be formed in a body on the bottom surface of the lower receptacle  80 . That is, the lower receptacle  80  may be made of a material having a high reflectivity, such as aluminum or aluminum alloys, and in this case, the lower receptacle itself may perform the function of the reflection sheet  75 . 
     The lower receptacle  80  is in the form of a rectangle, and has side walls formed along the edge of the upper surface thereof, in which the optical sheet  40 , the diffusion plate  50 , the light sources  70 , and the reflection sheet  75  are accommodated and fixed. 
     Hereinafter, with reference to  FIGS. 3 to 6 , the upper receptacle  10 , the first frame  30 , and the second frame  60  included in the display device  1  according to the first embodiment of the present invention will be described in detail.  FIG. 3  is a partial exploded perspective view, in accordance with an embodiment, explaining engagement of a first frame and a second frame included in the display device of  FIG. 1 , and  FIG. 4  is a partial perspective view, in accordance with an embodiment, of the display device of  FIG. 1 .  FIG. 5  is a sectional view, in accordance with an embodiment, of the display device, taken along line V-V′ in  FIG. 4 , and  FIG. 6  is an enlarged sectional view, in accordance with an embodiment, of area “A” in  FIG. 5 . 
     Referring to  FIG. 3 , the optical sheet  40  and the diffusion plate  50  are fixed between the first frame  30  and the second frame  60 . A first fixing projection  31  formed on the first frame  30  serves to fix the optical sheet  40  and the diffusion plate  50  and to fix the first frame  30  and the second frame  60 . 
     The first frame  30  forms seating surfaces of the display panel (See “ 20 ” in  FIG. 2 ). The first frame  30  includes the first fixing projection  31 , and fixes the optical sheet  40  and the diffusion plate  50 . The first frame  30  may be in the form of a tetragon having an open center part that forms an inner side surface thereof so that the first frame overlaps the edge of the display panel  20 . However, the shape of the first frame  30  is not limited to the tetragon, and the first frame  30  may be formed on one side or both sides of the edge of the display panel  20  as needed. 
     In addition, since the first frame  30  is formed to overlap the display panel  20 , it may be formed of a transparent material so that it is not visually recognized. The transparent material may be a plastic series transparent material such as poly methyl methacrylate (PMMA). As described above, by forming the first frame  30  with a transparent material, the first frame  30  may be prevented from being visually recognized as a dark part on the display panel  20 . Only a part of the first frame  30  may be formed of a transparent material. For example, a part of the first frame  30  that may be visually recognized as a dark part is formed of a transparent material, and the remaining part thereof is formed of an opaque material, so that light leakage to unnecessary parts through the first frame  30  may be prevented. The first frame  30  may be formed through injection molding, and an insert injection method may be used to form only a part of the first frame as a transparent material. 
     The first frame  30  includes the first fixing projection  31  formed on the lower part thereof. The first fixing projection  31  penetrates a first hole  41  formed on the optical sheet  40  and a second hole  51  formed on the diffusion plate  50 , and is inserted into a fixing hole  63  of the second frame  60 . 
     The first fixing projection  31  serves to fix the first frame  30  and the second frame  60  to each other, and to fix the optical sheet  40  and the diffusion sheet  50  to the second frame  60 . A plurality of first fixing projections  31  may be formed along the four sides of the first frame  30 . The diameter of the first fixing projection  31  may be adjusted in accordance with the width of the first frame  30 . The size and the number of the first fixing projections  31  may be properly set to prevent the movement of the optical sheet  40  and the diffusion plate  50 . 
     In addition, the first hole  41  and the second hole  51  may be formed on end parts of the optical sheet  40  and the diffusion plate  50 , and in order to maximize the area of the surface light sources, they may be formed at the edges of the optical sheet  40  and the diffusion plate  50 . If the edges of the optical sheet  40  and the diffusion plate  50  are fixed by the first fixing projection  31 , it is possible to maintain a state of the optical sheet  40  and the diffusion plate  50  always having an even surface. 
     The second frame  60  is positioned on the lower part of the first frame  30 , and forms seating surfaces of the optical sheet  40  and the diffusion plate  50 . The second frame  60  may have the thickness or width greater than those of the first frame  30 . The second frame  60  may include four wall surfaces  61  and inclined surfaces  62  extended from the wall surfaces. The four wall surfaces  61  may serve to maintain the stiffness of the second frame  60 , and the inclined surfaces  62  may serve to reflect the light of the light sources  70  to an upper side. 
     The first frame  30  and the second frame  60  include a first frame extension part  36  and a second frame extension part  64  projecting to an outside, respectively. Referring to  FIGS. 4 and 5 , the first frame extension part  36  and the second frame extension part  64  are fixed to a first opening  13  formed on the side-wall part  11  of the upper receptacle  10 . The first frame extension part  36  and the second frame extension part  64  serve to fix the first frame  30  and the second frame  60  to the upper receptacle  10 , respectively. 
     The first frame extension part  36  and the second frame extension part  64  may be formed to have a proper size so as to prevent the first frame extension part  36  and the second frame extension part  64  from being projected to an outside of the upper receptacle  10  through the first opening  13 . If the first frame extension part  36  and the second frame extension part  64  are projected to the outside of the upper receptacle  10 , it may cause an obstacle in forming a multi-display device by connecting a plurality of display devices together. The optical sheet  40  and the diffusion plate  50  may be formed in the form of a tetragon without forming the projecting parts such as the first frame extension part  36  and the second frame extension part  64 . 
     According to the structure in which the first frame  30  and the second frame  60  are fixed to the first opening  13  formed on the side-wall part  11  of the upper receptacle  10  as described above, the first frame  30  and the second frame  60  may be engaged with the upper receptacle  10  through a simple structural modification without adding any separate component. 
     In addition, the bezel part  12  of the upper receptacle  10  may be doubly formed to reinforce the stiffness thereof. The upper receptacle may be formed by processing a metallic plate material. The metallic material may be a thin film member formed by bending the metallic plate material. Particularly, in order to heighten the stiffness of the bezel part  12  with the width of the bezel part  12  narrowed, the bezel part  12  may be formed by folding the metallic plate material twice or more. A hemming process may be adopted to fold the metallic plate material twice or more. The bezel part  12  may be formed to expose the display area of the display panel  20  to an outside and to overlap the non-display area. 
     Referring to  FIG. 6 , the width W 1  of the bezel part  12  may be smaller than the width W 2  of the first frame  30 . The bezel part  12  may be formed only on the non-display area of the display panel  20 , but the first frame  30  may partially overlap the display area of the display panel  20 . As described above, since the first frame  30  is formed of a transparent material, it may not be visually recognized as a dark part on the display panel  20  even if the first frame  30  partially overlaps the display area of the display panel. The first frame  30  may include a curved (e.g., rounded) part  34  and a straight (e.g., flat) part  35  formed on an inner surface thereof so that a part of the first frame  30  overlapping the display area is not visually recognized. 
     Specifically, the first frame  30  may be formed in the form of a tetragon having an open center part that forms an inner side surface thereof. The first frame  30  includes an upper surface  32  on which the display panel is seated, and a lower surface  33  which is opposite to the upper surface  32  and is in contact with the optical sheet  40 . The first frame  30  also includes the curved part  34  and the straight part  35  that connects between the upper surface  32  and the lower surface  33  and forms an inner surface of the first frame  30 . 
     The width of the lower surface  33  of the first frame  30  may be set to be smaller than the width of the upper surface  32 . In this case, the upper surface  32  is in contact with the curved part  34 , and the curved part  34  is extended to the straight part  35  and becomes in contact with the lower surface  33 . 
     The curved part  34  and the straight part  35  of the first frame  30  may offset the difference in refractive index of light caused by the first frame  30 , and thus the visual recognition of the dark part on the display panel  20  may be prevented. The curved part  34  is formed to be in contact with the upper surface  32 , and the sectional shape of the curved part  34  may be, for example, circular or partially elliptical. Also, the straight part  35  connects the curved part  34  and the lower surface  33 , and may be obliquely extended. 
     On the lower surface  33 , the first fixing projection  31  may be formed. The region of the first frame  30  overlapping the bezel part  12  may be formed of an opaque material, and the region of the first frame  30  overlapping the display area may be formed of a transparent material. The width of the upper surface  32  of the first frame  30  may be smaller than the width of the upper surface of the second frame  60 . 
     In addition, between the upper receptacle  10  and the display panel  20 , a buffering member  15  that protects the display panel  20  and prevents light leakage may be interposed. The buffering member  15  may be formed of an elastic material to protect the display panel  20  from the metallic upper receptacle  10 . The buffering member  15  may be formed along the bezel part  12  of the upper receptacle  10 , and may be made of an opaque material. 
     Hereinafter, with reference to  FIGS. 7 to 9 , a display device according to a second embodiment of the present invention will be described.  FIG. 7  is a partial perspective view of a display device according to a second embodiment of the present invention.  FIG. 8  is a partial exploded perspective view, in accordance with an embodiment, explaining engagement of a first frame and a second frame included in the display device of  FIG. 7 , and  FIG. 9  is a sectional view, in accordance with an embodiment, of the display device, taken along line IX-IX′ in  FIG. 7 . For convenience in explanation, the same drawing reference numerals are used for the same elements as the first embodiment, and the detailed description thereof will be omitted. 
     A display device  1  according to the second embodiment of the present invention includes a second fixing projection  65  formed on the second frame  60 ′ to facilitate the assembling of the optical sheet  40  and the diffusion plate  50 . 
     The first frame  30  forms seating surfaces of the display panel  20 . The first frame  30  includes the first fixing projection  31 , and fixes the optical sheet  40  and the diffusion plate  50 . The first frame  30  may be in the form of a tetragon having an open center part that forms an inner side surface thereof so that the first frame  30  overlaps the edge of the display panel  20 . The first frame  30  includes the first fixing projection  31  formed on the lower part thereof. The first fixing projection  31  penetrates the first hole  41  formed on the optical sheet  40  and the second hole  51  formed on the diffusion plate  50 , and is inserted into a fixing hole  63  of the second frame  60 ′. The first fixing projection  31  serves to fix the first frame  30  and the second frame  60 ′ to each other, and to fix the optical sheet  40  and the diffusion sheet  50  to the second frame  60 ′. A plurality of first fixing projections  31  may be formed along the four sides of the first frame  30 . 
     On the second frame  60 ′, the fixing hole  63 , which is engaged with the first fixing projection  31 , and the second fixing projection  65  are formed. The second fixing projection  65  enables the optical sheet  40  and the diffusion plate  50  to be easily fixed to the second frame  60 ′. 
     In the process of assembling the optical sheet  40  and the diffusion plate  50 , the optical sheet  40  and the diffusion plate  50  may be seated on the second frame  60 ′, and the first frame  30  may be moved above parts of the optical sheet  40  and the diffusion plate  50  to assemble the optical sheet  40  and the diffusion plate  50 . If there is no structure capable of fixing the optical sheet  40  and the diffusion plate  50  on the second frame  60 ′, it may not be easy to arrange the optical sheet  40  and the diffusion plate  50  so that the first hole  41  of the optical sheet  40  and the second hole  51  of the diffusion plate  50  coincide with each other. Accordingly, in order to easily arrange the optical sheet  40  and the diffusion plate  50  on the second frame  60 ′, the second fixing projection  65  may be formed on the second frame  60 ′. 
     The second frame  60 ′ includes four wall surfaces  61  and inclined surfaces  62  extended from the four wall surfaces  61 . Second fixing projections  65  may be formed on the four wall surfaces  61 . The height of the second fixing projection  65  may be adjusted in consideration of the thicknesses of the diffusion plate  50  and the optical sheet  40 . Since it is not necessary for the second fixing projection  65  to fix the first frame  30  and the second frame  60 ′, the height of the second fixing projection  65  may be set to be somewhat higher than the thickness of the diffusion plate  50 . 
     The second fixing projection  65  may be formed to overlap the bezel part  12  of the upper receptacle  10 . In other words, to prevent the second fixing projection  65  from being visually recognized on the display panel  20 , it may be formed in the non-display area of the display panel  20 . 
     The second fixing projection  65  may be formed in a body (e.g., integrally) with the second frame  60 ′. The shape of the second fixing projection  65  is not, however, limited thereto, and the second fixing projection  65  and the second frame  60 ′ may be separately formed and then engaged with each other. For example, in order to prevent the second fixing projection  65  from being visually recognized on the display panel  20 , it may be formed of a transparent material, and then may be fixed to the second frame  60 ′. Also, in order to form the second fixing projection  65  with a transparent structure, an insert molding method may be used so that only the second fixing projection  65  is formed by inserting a transparent material, and the remaining part is formed in mold. 
     On the optical sheet  40  and the diffusion plate  50 , a third hole  42  and a fourth hole  52 , into which the second fixing projections  65  may be inserted, may be formed. In the same manner as the first hole  41  and the second hole  51 , the third hole  42  and the fourth hole  52  may be formed at edges of the optical sheet  40  and the diffusion plate  50 . The diameter of the third hole  42  and the fourth hole  52  may be smaller than the diameter of the first hole  41  and the second hole  51 . 
     Hereinafter, with reference to  FIGS. 10 to 12 , a display device according to a third embodiment of the present invention will be described in detail.  FIG. 10  is a partial perspective view of a display device according to a third embodiment of the present invention,  FIG. 11  is a partial exploded perspective view, in accordance with an embodiment, explaining engagement of a first frame and a second frame included in the display device of  FIG. 10 , and  FIG. 12  is a sectional view, in accordance with an embodiment, of the display device, taken along line XII-XII′ in  FIG. 10 . For convenience in explanation, the same drawing reference numerals are used for the same elements as the first embodiment, and the detailed description thereof will be omitted. 
     A display device  1  according to the third embodiment of the present invention includes a reinforcement part  16  reinforcing the stiffness of the bezel part  12 ′ of the upper receptacle  10 ′, and the first frame  30 ′ and the second frame  60  are in hook engagement with each other. 
     The first frame  30 ′ forms seating surfaces of the display panel  20 . The first frame  30 ′ includes the first fixing projection  31 , and fixes the optical sheet  40  and the diffusion plate  50 . The first frame  30 ′ may be in the form of a tetragon having an open center part that forms an inner side surface thereof so that the first frame  30 ′ overlaps the edge of the display panel  20 . The first frame  30 ′ includes the first fixing projection  31  formed on the lower part thereof. The first fixing projection  31  penetrates the first hole  41  formed on the optical sheet  40  and the second hole  51  formed on the diffusion plate  50 , and is inserted into a fixing hole  63  of the second frame  60 . The first fixing projection  31  serves to fix the first frame  30 ′ and the second frame  60  to each other, and to fix the optical sheet  40  and the diffusion sheet  50  to the second frame  60 . A plurality of first fixing projections  31  may be formed along the four sides of the first frame  30 ′. 
     The first frame  30 ′ includes a hook member  37  for hook engagement with the second frame  60 . The first frame  30 ′ and the second frame  60  may be engaged with each other through the first fixing projection  31  and the fixing hole  63 . In order to reinforce the engagement force of the first frame  30 ′ and the second frame  60 , the first frame  30 ′ includes the hook member  37 . The hook member  37 , which is in the form of a hook, is formed on the outside of the first frame  30 ′. The hook member  37  may be hook-engaged with one end part of the second frame  60 . The second frame  60  includes four wall surfaces  61  and inclined surfaces  62  extended from the four wall surfaces  61 . 
     In addition, on the side-wall part  11  of the upper receptacle  10 ′, a second opening  14  is formed. The second opening  14  exposes at least a part of the hook member  37  of the first frame  30 ′. Since at least a part of the hook member  37  is exposed, a space provided on the inside of the upper receptacle  10 ′ is reduced, and thus the width of the bezel part  12 ′ of the upper receptacle  10 ′ may be reduced. The hook member  37  and upper receptacle  10 ′ may be formed so that the hook member  37  is not exposed to an outside through the side-wall part  11  of the upper receptacle  10 ′. 
     The bezel part  12 ′ of the upper receptacle  10 ′ includes a reinforcement part  16  for reinforcing the stiffness. The reinforcement part  16  may be formed by making the surface of the bezel part  12 ′ curved downward. That is, the reinforcement part may be in the form of a furrow that is in parallel to the bezel part  12 ′. By forming the reinforcement part in the form of a furrow on the bezel part  12 ′, a narrow and strong bezel part  12 ′ may be provided. The shape of the reinforcement part  16  is not, however, limited thereto, and the reinforcement part  16  may also be formed by making a part of the bezel part  12 ′ project upward in parallel to the side-wall part  11 . 
     Hereinafter, with reference to  FIG. 13 , a multi-display device provided by connecting a plurality of display devices according to an embodiment of the present invention will be described in detail.  FIG. 13  is a perspective view of a multi-display device according to an embodiment including display devices according to one or more embodiments of the present invention. 
     Referring to  FIGS. 1 and 13 , a multi-display device  100  is formed by joining a plurality of display devices  1  in the form of a matrix. The multi-display device  100  includes all display screens of the display devices  1 , and thus is provided with a large-area screen. In this case, each display device  1  forms a unit display device, and the respective bezel parts  12  of the display devices  1  form non-display regions on the large-area screen. Since the bezel parts  12  of the respective display devices  1  may be visually recognized on the large-area screen, there is a need for a structure that can minimize the size of the bezel part  12 . 
     Although some embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.