RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0035832 filed in the Korean Intellectual Property Office on Apr. 18, 2011, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The described technology generally relates to a lighting apparatus, more particularly, an organic light emitting diode (OLED) lighting apparatus. 
     2. Description of the Related Technology 
     An OLED emits light using energy that is generated when excitons are dropped from an exited state to a ground state after the excitons are formed by coupling electrons and holes in an organic emission layer. 
     Since OLED lighting apparatuses simply generate light, they have a relatively simple structure compared to an OLED display which generates an image. 
     In general, an OLED lighting apparatus includes an insulation substrate made of a glass material or an insulation substrate made of a plastic material having comparatively low thermal conductivity. Such insulation substrates, however, cannot radiate heat generated from the OLED to the environment. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     One inventive aspect is an organic light emitting diode lighting apparatus which has improved heat dissipating efficiency, a prolonged life-span and enhanced durability. 
     Another aspect is an organic light emitting diode lighting apparatus including a substrate main body including a light emitting area and a sealing area surrounding the light emitting area, an organic light emitting diode disposed on the light emitting area of the substrate main body, a sealant disposed on the sealing area of the substrate main body, and an encapsulation substrate sealed with the substrate main body through the sealant and including a heat dissipating wire. The heat dissipating wire may include a heat absorption portion disposed on one side of the encapsulation substrate, which faces the sealant, a heat dissipating portion disposed on an opposite side of the one side, and a coupling portion for connecting the absorption portion and the heat dissipating portion. 
     The heat absorption portion may contact a space sealed between the substrate main body and the encapsulation substrate. 
     The sealant may include a heat transfer material. 
     The heat transfer material may be a conductive particulate. 
     The coupling portion may pass through part of the encapsulation substrate. 
     The heat dissipating wire may include at least one of a metal, a metal oxide, graphite, and silicon. 
     The encapsulation substrate may be one of a glass substrate, an acryl plastic substrate, and a polyaniline plastic substrate. 
     The substrate main body may be one of a glass substrate, an acryl plastic substrate, and a polyaniline plastic substrate. 
     The encapsulation substrate may include a concave portion corresponding to the light emitting area of the substrate main body to be separated from the light emitting diode at the light emitting area. 
     The encapsulation substrate may include at least one through-hole formed in an area overlapped with the sealant. 
     The coupling portion may be disposed in the through-hole of the encapsulation substrate. 
     The coupling portion may be disposed along an outer side of the encapsulation substrate. 
     The encapsulation substrate may include a third surface interconnecting the first and second surfaces, and the coupling portion may contact the third surface of the encapsulation substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an organic light emitting diode lighting (OLED) apparatus according to a first embodiment. 
         FIG. 2  is a cross-sectional view of an OLED lighting apparatus according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, only certain embodiments have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways. 
     Throughout the specification, the same or similar constituent elements are designated by the same reference numerals. For various embodiments, constituent elements having the same constitution are explained representatively in the first embodiment. In the second embodiments, only the constituent elements different from those in the first embodiment are described. 
     In the drawings, the size and thickness of each element is approximately shown for better understanding and ease of description. Therefore, the drawings are not considered limiting. 
     In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Further, in the drawings, the thicknesses of layers and regions are exaggerated for better understanding and ease of description. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. 
     Hereinafter, an OLED lighting apparatus  101  according to a first exemplary embodiment will be described with reference to  FIG. 1 . 
     As shown in  FIG. 1 , the OLED lighting apparatus  101  includes a substrate main body  100 , an organic light emitting diode (OLED)  70 , a sealant  300 , and an encapsulation substrate  200 . 
     The substrate main body  100  may be a transparent substrate made of glass, quartz, or ceramic, or may be a plastic substrate made of a material such as acryl, polyimide, and polyaniline. 
     The substrate main body  100  is divided into a light emitting area, and a sealing area that surrounds the light emitting area. The organic light emitting diode  70  is disposed on the light emitting area, and the sealant  300  is disposed on the sealing area. 
     The organic light emitting diode  70  includes a first electrode  710  disposed on the substrate main body  100 , an organic emission layer  720  disposed on the first electrode  710 , and a second electrode  730  disposed on the organic emission layer  710 . 
     In one embodiment, the first electrode  710  is a hole-injection electrode that injects holes into the organic emission layer  720 , and the second electrode  730  is an electron-injection electrode that injects electrons into the organic emission layer  720 . The first embodiment, however, is not limited thereto. The first electrode  710  may be an electron-injection electrode and the second electrode  730  may be a hole-injection electrode. 
     Further, the first electrode  710  may be formed as a transparent conductive layer or a semi-transparent layer. The second electrode  730  may be formed as a reflective layer. 
     The transparent conductive layer may be include at least one of indium tin oxide (ITO), indium zinc oxide (IZO), zinc indium tin oxide (ZITO), gallium indium tin oxide (GITO), indium oxide (In 2 O 3 ), zinc oxide (ZnO), gallium indium zinc oxide (GIZO), gallium zinc oxide (GZO), fluorine tin oxide (FTO), and aluminum-doped zinc oxide (AZO). Such a transparent conductive layer has a comparatively high work function. Therefore, the first electrode  710  formed as the transparent conductive layer can smoothly perform hole injection. When the first electrode  710  is formed as the transparent conductive layer, the OLED lighting apparatus  101  may further include an auxiliary electrode made of a metal having comparatively low resistivity in order to compensate for a comparatively high resistivity of the first electrode  710 . 
     The reflective layer and the semi-transparent layer may be made of metal such as magnesium (Mg), calcium (Ca), lithium (Li), zinc (Zn), aluminum (Al), or alloys thereof. The reflective layer and the semi-transparent layer are determined by thickness. In general, the semi-transparent layer has a thickness that is less than about 200 nm. The light transmittance of the semi-transparent layer increases as the semi-transparent layer becomes thinner. The light transmittance of the semi-transparent layer decreases as the semi-transparent layer becomes thicker. 
     In the first embodiment, the reflective layer and the semi-transparent layer are the second electrode  730 , which is the electron injection electrode. Accordingly, the reflective layer and the semi-transparent layer may be made of a metal having a comparatively lower work function, for example lower than about 4.5 eV. 
     Furthermore, when the first electrode  710  is formed as a semi-transparent electrode and the second electrode  730  is formed as a reflective layer, light use efficiency can be improved using the microcavity effect. 
     Moreover, the first electrode  710  may be formed as a multilayer structure including a transparent conductive layer and a semi-transparent layer. In this case, the microcavity effect can be achieved while the first electrode  710  has a comparatively high work function. 
     The organic emission layer  720  may be formed as a multilayer including at least one of an emission layer, a hole-injection layer (HIL), a hole-transporting layer (HTL), an electron-transporting layer (ETL), and electron-injection layer (EIL). The above layers except the emission layer may be omitted as needed. When the organic emission layer  720  includes all of the described layers, the hole-injection layer (HIL) is disposed on the first electrode  710 , which is a hole-injection electrode. The hole-transporting layer (HTL), the emission layer, electron-transporting layer (ETL), and the electron-injection layer (EIL) are sequentially stacked on the hole-injection layer (HIL). Furthermore, the organic emission layer  720  may further include other layers as needed. For example, the organic emission layer  720  may further include a resonance layer for maximizing the microcavity effect. 
     The OLED lighting apparatus  101  has a bottom emission structure in which light generated from the organic emission layer  720  is emitted to the environment through the first electrode  710  and the substrate main body  100 . In  FIG. 1 , an arrow drawn as a dotted line indicates a direction in which light is emitted. 
     The sealant  300  is disposed on the sealing area of the substrate main body  100 . The sealant  300  may be made of frit or a thermosetting resin. Also, the sealant  300  may include a heat transfer material. For example, a conductive particulate may be used as the heat transfer material. 
     The encapsulation substrate  200  is sealed with the substrate main body  100  through the sealant  300 , thereby covering the organic light emitting diode  70 . The encapsulation substrate  200  is a glass substrate or a plastic substrate such as acryl, polyimide, and polyaniline. 
     Meanwhile, when the substrate main body  100  and the encapsulation substrate  200  are made of the plastic substrate, the OLED lighting apparatus  101  may have flexibility. 
     Furthermore, the encapsulation substrate  200  has a sunken or a concave portion corresponding to the light emitting area of the substrate main body  100  whereon the OLED  70  is formed. Therefore, the encapsulation substrate  200  is stably separated from the organic light emitting diode  70  while the encapsulation substrate  200  is sealed with the substrate main body  100  through the sealant  500 . Accordingly, the encapsulation substrate  200  protects the organic light emitting element  70  from damage. 
     Further, the encapsulation substrate  200  includes a heat dissipating wire  400 . The heat dissipating wire  400  includes at least one of a metal, a metal oxide, graphite, and silicon. For example, the heat dissipating wire  400  may include at least one of Al, Ag, Au, Cr, Mg, Mo, W, and Cu. 
     The heat dissipating wire  400  includes a heat absorption portion  401 , a heat dissipating portion  403 , and a coupling portion  402 . The heat absorption portion  401  is disposed on one side of the encapsulation substrate  200 , which faces the sealant  300 . The heat dissipating portion  403  is disposed on the opposite side of the one side facing the sealant  300 . The coupling portion  402  connects the heat absorption portion  401  and the heat dissipating portion  403 . 
     The heat absorption portion  401  absorbs heat generated by the organic light emitting diode  70 . The heat absorption portion  401  may contact a space sealed between the substrate main body  100  and the encapsulation substrate  200 . The larger is the area where the heat absorption portion  401  contacts the sealed area, the more effectively the heat absorption portion  401  absorbs the heat generated by the organic light emitting diode  70 . The heat transfer material included in the sealant  300  assists the heat absorption portion  401  to absorb heat radiated from the organic light emitting diode  70 . 
     The heat dissipating portion  403  radiates the heat absorbed by the heat absorption portion  401  to the environment. The heat dissipating efficiency improves as the heat dissipating portion  403  becomes larger. Accordingly, the heat dissipating portion  403  may be formed over the entire outer surface of the encapsulation substrate  200  in order to maximize the heat dissipating efficiency. 
     The coupling portion  402  transfers the absorbed heat of the heat absorption portion  401  to the heat dissipating portion  403 . In the first embodiment, the encapsulation substrate  200  may further include at least one of through-holes  202  formed at one area overlapped with the sealant  300 , and the coupling portion  402  of the heat dissipating wire  400  is disposed in the through-hole  202  of the encapsulation substrate  200 . 
     As described above, the OLED lighting apparatus  101  has a structure that can effectively radiate heat generated from the OLED  70  to the environment. Accordingly, deterioration of the organic light emitting element  70  by heat can be suppressed, and the life-span and durability of the OLED lighting apparatus  101  can be improved. 
     Hereinafter, an organic light emitting diode (OLED) lighting apparatus according to a second exemplary embodiment will be described with reference to  FIG. 2 . 
     As shown in  FIG. 2 , an OLED lighting apparatus  102  includes a heat dissipating wire  500  having a coupling portion  502  formed along an outer side of an encapsulation substrate  200 . That is, except an area facing the light emitting area of the substrate main body  100 , the encapsulation substrate  200  is substantially entirely surrounded by a heat absorption portion  501 , a coupling portion  502 , and a heat dissipating portion  503  of the heat dissipating wire  500 . Accordingly, the heat dissipating wire  500  may have further improved heat dissipating efficiency. 
     Like the first embodiment, the heat absorption portion  501  may contact a sealed space between the substrate main body  100  and the encapsulation substrate  200 . 
     As described above, the OLED lighting apparatus  102  has a structure that can effectively radiate the heat generated from the organic light emitting diode  70 . 
     Hereinafter, an experimental example according to the first embodiment will be compared with a comparative example with reference to Table 1. 
     The experimental example includes a heat dissipating wire according to the first embodiment. The comparative example has a structure including a simple heat dissipating layer at one side of an encapsulation substrate. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Experimental Example 
                 Comparative Example 
               
               
                 thickness (μm) 
                 temperature (° C.) 
                 temperature (° C.) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2 
                 82.05 
                 83.75 
               
               
                 50 
                 78.25 
                 83.75 
               
               
                 200 
                 66.16 
                 83.75 
               
               
                 500 
                 52.25 
                 83.75 
               
               
                 1000 
                 41.44 
                 83.75 
               
               
                   
               
             
          
         
       
     
     As shown in Table 1, the experimental example according to the first embodiment has better heat dissipating efficiency than that of the comparative example. Particularly, the heat dissipating efficiency is greatly improved as the heat dissipating wire becomes thicker. On the contrary, the heat dissipating efficiency of the comparative example is not improved although the heat dissipating layer becomes thicker. 
     At least one of the disclosed embodiments can improve heat dissipating efficiency of an OLED lighting apparatus. Furthermore, degradation of an OLED element by heat can be suppressed, and the life-span and durability of the OLED lighting apparatus can be improved. 
     While embodiments have been described in connection with the accompanying drawings, it is to be understood that the disclosed embodiments are not considered limiting and are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
An organic light emitting diode (OLED) lighting apparatus is disclosed. In one embodiment, the apparatus includes i) a substrate main body including a light emitting area and a sealing area surrounding the light emitting area, ii) an OLED disposed on the light emitting area of the substrate main body, iii) a sealant disposed on the sealing area of the substrate main body and iv) an encapsulation substrate encapsulating the OLED, wherein the encapsulation substrate comprises first and second surfaces opposing each other. The apparatus may further include a heat dissipating wire configured to dissipate heat generated by the OLED. The heat dissipating wire includes a heat absorption portion disposed on the first surface of the encapsulation substrate and contacting the sealant, a heat dissipating portion disposed on the second surface, and a coupling portion interconnecting the absorption portion and the heat dissipating portion.