Abstract:
Disclosed is an organic light emitting device according to the present invention comprising: a first substrate comprising an emission region and a non-emission region; 
     a sub-pixel located on the first substrate, the sub-pixel comprising a first electrode, an emission layer, and a second electrode; and a barrier rib located on the substrate comprising the first electrode, the barrier rib patterning the second electrode, wherein a volume per unit area of a portion of the barrier rib located on the non-emission region is different from that of the other portion of the barrier rib located on the emission region.

Description:
CROSS-REFERENCE 
       [0001]    This application claims priority to and the benefit of Korea Patent Application No. 10-2006-0029600, filed on Mar. 31, 2006, the entire content of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to an organic light emitting display. 
         [0004]    2. Related Art 
         [0005]    In recent years, a flat panel display (FPD) increasingly becomes important with the development of multimedia. Hence, various flat panel displays such as a plasma display panel (PDP), a field emission display (FED), and an organic light emitting display (OLED) have been put to practical use. 
         [0006]    In portionicular, an organic light emitting display has an advantage in that it has a high response speed lower than 1 ms and low consumption power, as well as emits light by itself. In addition, the organic light emitting display is advantageous as a motion image display medium because it does not have a trouble in the view angle without respect to its size. Furthermore, the organic light emitting display has come into the spotlight as a next generation flat panel display because it can be simply manufactured with existing semiconductor manufacturing processes at a low temperature. 
         [0007]      FIG. 1  is a plan view illustrating a structure of an organic light emitting display according to the prior art,  FIG. 2  is a portionially enlarged view of the organic light emitting display in  FIG. 1 , and  FIG. 3  is a cross sectional view of the organic light emitting display taken along line I-I′ of  FIG. 2 . 
         [0008]    Referring to  FIGS. 1 to 3 , an organic light emitting display according to the prior art comprises a substrate  100  comprising a non-emission region N and an emission region E, on which there are arranged sub-pixels, each comprising a first electrode  110 , an emission layer  120 , and a second electrode  130 . Here, a first region where sub-pixels are arranged is defined as an emission region E, and a second region other than the first region is defined as a non-emission region N. 
         [0009]    On the non-emission region N of the substrate  100  there are provided sealant  160  and wires (not shown) to apply electrical signals to the first electrode  110  and the second electrode  130 . 
         [0010]    More specifically, the first electrode  110  is patterned on the substrate  100  in a stripe form. And, wires (not shown), which are spaced from the first electrode  110  and have the same material as the first electrode  110 , are provided. On a portion of the first electrode  110  and wires (not shown) there is provided an insulating film  115  comprising an opening  116  for exposing a portion of the first electrode  110  and a contact portion  117  for exposing a portion of the wires (not shown). On the insulating film  115  there are provided barrier ribs  118  formed to be spaced from each other in the direction of intersecting the first electrode  110 , and in the opening  116  there is provided the emission layer  120 . The second electrode  130  is located on the substrate comprising the emission layer  120  and contact portion  117 , and the second electrode  130  is patterned by the barrier ribs  118 . And, the sealant  160  is provided on the non-emission region N of the substrate  100  to surround the emission region E. And, the substrate  100  provided with the sub-pixels is attached to an encapsulation substrate (not-shown) by the sealant  160  to protect the emission portion from external moisture or oxygen. 
         [0011]    At this time, however, the sealant  160  can be flowed into the emission region E as shown in  FIGS. 2 and 3(C) . That is, a capillary phenomenon created by a pressure applied when the substrate  110  and the encapsulation substrate  170  are attached to each other causes the sealant  160  to flow into the emission region E along the lower space of barrier ribs having overhang structures. 
         [0012]    The flowed sealant  160  may cause damage to an outer circumference of the emission layer  120 , thereby to reduce reliability and emission efficiency of elements. 
       SUMMARY 
       [0013]    Accordingly, the present invention is provided to substantially obviate one or more problems due to limitations and disadvantages of the related art. 
         [0014]    To achieve the above objects, there is provided an organic light emitting device according to the present invention comprising: a first substrate comprising an emission region and a non-emission region; a sub-pixel located on the first substrate, the sub-pixel comprising a first electrode, an emission layer, and a second electrode; and a barrier rib located on the substrate comprising the first electrode, the barrier rib patterning the second electrode, wherein a volume per unit area of a portion of the barrier rib located on the non-emission region is different from that of the other portion of the barrier rib located on the emission region. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a plan view illustrating an organic light emitting display according to the prior art. 
           [0016]      FIG. 2  is a portionially enlarged view of the organic light emitting display in  FIG. 1 . 
           [0017]      FIG. 3  is a cross sectional view of the organic light emitting display taken along line I-I′ of  FIG. 2 . 
           [0018]      FIG. 4  is a plan view of an organic light emitting display according to a first embodiment of the present invention. 
           [0019]      FIG. 5  is a portionially enlarged view of the organic light emitting display in  FIG. 4 . 
           [0020]      FIG. 6  is a cross sectional view of the organic light emitting display taken along line II-II′ of  FIG. 4 . 
           [0021]      FIG. 4  is a plan view illustrating a portion of a barrier rib of an organic light emitting display according to a first embodiment of the present invention. 
           [0022]      FIG. 7B  is a cross sectional view of the barrier rib taken along line A-A′ of  FIG. 7A . 
           [0023]      FIG. 7C  is a cross sectional view of the barrier rib taken along line B-B′ of  FIG. 7A . 
           [0024]      FIG. 8  is a plan view illustrating an organic light emitting display according to a second embodiment of the present invention. 
           [0025]      FIG. 9  is a cross sectional view of a barrier rib of the organic light emitting display according to the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0026]    Referring to  FIGS. 4 to 6 , an organic light emitting display comprises a substrate  200  comprising a non-emission region N and an emission region E, on which there are arranged sub-pixels, each comprising a first electrode  210 , an emission layer  220 , and a second electrode  230 . On the non-emission region N of the substrate  200  there are provided sealant  260  and wires (not shown) to apply electrical signals to the first electrode  210  and the second electrode  230 . 
         [0027]    More specifically, the first electrode  210  is patterned on the substrate  200  in a stripe form. And, wires (not shown), which are spaced from the first electrode  210  and have the same material as the first electrode  210 , are provided. 
         [0028]    The first electrode  210  may be an anode and may comprise a transparent conductive layer having a high work function such as ITO(Indium Tin Oxide). And, the wires(not shown) may further comprise a metallic layer disposed on a transparent conductive film other than the transparent conductive layer. 
         [0029]    An insulating film  215  is disposed on a portion of the first electrodes  210  and wires (not shown). The insulating film  215  may comprise an opening  216  for exposing a portion of the first electrode  210  and a contact portion  217  for exposing a portion of the wires (not shown). And, on the insulating film  215  there are disposed barrier ribs  218  formed in the direction of intersecting the first electrode  210 . The barrier ribs  218  are formed to be spaced from each other. And, the width of a portion of a barrier rib  218  located on the non-emission region N may be narrower than that of a portion of a barrier rib  218  located on the emission region E. 
         [0030]    More specifically, the width of a portion of a barrier rib  218  located on the non-emission region N, i.e. the width of an end portion, may become narrower as it goes to the outer circumference of the substrate as shown in  FIGS. 7A to 7C . At this time, it is desirable that the end portion of the barrier rib  218  located on the non-emission region N is formed to have a length of more than 0 μm and less than 100 μm. 
         [0031]    A cross section of the end portion of the barrier rib  218  located on the emission region E, taken along the line A-A′, may have a reverse taper shape so that the second electrode  230  may be patterned. That is, each (θ1) of two base angles at the cross section taken along the line A-A′ may be greater than 90 degrees. And, a cross section of the end portion of the barrier rib  218  located on the non-emission region N, taken along the line B-B′ may have a taper shape, and each θ2 of two base angles at the cross section taken along the line B-B′ may be more than 10 degrees and less than 90 degrees. 
         [0032]    The barrier rib  218  having the above-mentioned structure can be formed by selectively etching the end portion of the barrier rib located on the non-emission region N through a well known process such as lithography or sandblasting. 
         [0033]    Returning to  FIGS. 4 to 6 , the sealant  260  is applied on a portion of the non-emission region, and the substrate  200  having the above-mentioned structure is attached to the encapsulation substrate  270  by the sealant  260 . 
         [0034]    At this time, the organic light emitting device according to a first embodiment of the present invention can reduce the phenomenon where the sealant  260  flows into the emission region as shown in  FIGS. 5 and 6 , since the width of the end portion of the barrier rib  218  located on the non-emission region N is formed to be narrower than that of the end portion of the barrier rib  218  located on the emission region E. That is, the organic light emitting device according to the embodiment of the present invention can reduce the phenomenon caused by a capillary phenomenon as in the prior art, where the sealant  260  flows into the emission region E, by making the width of the end portion of the barrier rib  218  located on the non-emission region N narrow to secure a space. 
         [0035]      FIG. 8  is a plan view illustrating an organic light emitting display according to a second embodiment of the present invention. 
         [0036]    Referring to  FIG. 8 , the organic light emitting display according to the second embodiment of the present invention, has the same construction as the first embodiment of the present invention except that a barrier  365  is further provided between the barrier rib  318  and sealant  360 . 
         [0037]    That is, on a substrate  300  according to the second embodiment of the present invention there are located a first electrode  310  patterned in a stripe form and wires (not shown), and on a portion of the first electrode  310  and wires there is provided an insulating film  315  comprising an opening  316  for exposing a portion of the first electrode  310  and a contact portion  317  for exposing a portion of the wires (not shown). And, on the insulating film  315  there are disposed barrier ribs  318  formed to be spaced from each other in the direction of intersecting the first electrode  310 , where the width of a barrier rib  318  located on the non-emission region N may be narrower than that of a barrier rib  318  located on the emission region E. 
         [0038]    And, a barrier  365  may be disposed between the emission region E and sealant  360 . The barrier  365  of the organic light emitting display according to the second embodiment of the present invention can be formed in one or more layers, and prevent the sealant  360  from flowing into the emission region E. The location where the barrier  365  is to be formed may be selected depending on how much sealant  360  is flowed into the emission region E. 
         [0039]    That is, the organic light emitting display according to the second embodiment of the present invention can prevent sealant  360  from flowing into the emission region when the substrate  300  and the encapsulation substrate  370  are attached to each other, primarily by the barrier and secondarily by the barrier rib  318 . 
         [0040]    Therefore, the organic light emitting display according to the second embodiment of the present invention can prevent more efficiently sealant from flowing into the emission region compared to the organic light emitting display according to the first embodiment of the present invention. 
         [0041]      FIG. 9  is a plan view illustrating a structure of a barrier rib according to the second embodiment of the present invention. 
         [0042]    Referring to  FIG. 9 , a portion of the barrier rib according to the second embodiment, which is located on the non-emission region, has narrower width than the other portion thereof, which is located on the emission region, and the portion of the barrier rib which is located on the emission region becomes narrower in width as going to the outer circumference of the substrate and has a bent where the width decreases sharply. 
         [0043]    Accordingly, the organic light emitting display according to the second embodiment of the present invention can reduce dramatically a capillary phenomenon since the width of the end portion of the barrier rib located on the non-emission region decreases prominently compared to the barrier rib according to the first embodiment of the present invention. As a consequence, the barrier rib according to the second embodiment can prevent the inflow of sealant effectively. 
         [0044]    While the above-mentioned embodiments illustrate a case where the width of a portion of the barrier rib located on the non-emission region is narrower than that of the other portion of the barrier rib located on the emission region, the structure of the barrier rib is not limited thereto, and therefore the height of a portion of the barrier rib located on the non-emission region may be lower than that of the other portion of the barrier rib located on the emission region. And, both of height and width of the portion of the barrier rib located on the non-emission region may be adjusted at the same time. 
         [0045]    In addition, while the barrier ribs according to the embodiments of the present invention have been described to be formed by photolithography or sandblasting, but not limited thereto, various processes can be applicable to form the barrier ribs. 
         [0046]    And, while the barrier ribs according to the embodiments of the present invention have been described to be formed in a singe layer, they can also be formed in a double layer.