Abstract:
The present invention provides a light emitting display with excellent reliability by preventing degradation by heat such as color changes or luminance reduction, through uniform and quick discharge of heat generated internally.

Description:
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application Nos. 10-2005-0028733 filed in Korea on Apr. 6, 2005 and 10-2005-0038967, 10-2005-0038936 filed in Korea on May 10, 2005 the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light emitting display. 
     2. Description of the Related Art 
     A light emitting device used in a light emitting display is an active light emitting device in which a light emitting layer is formed between two electrodes. The device is classified into an inorganic light emitting device and an organic light emitting device depending on the light emitting material. The light emitting device is also classified into a passive matrix type device and an active matrix type device depending on the driving method of light emitting layer. 
     The lifetime of a light emitting display is determined mainly by driving time of the display and degradation of the light emitting device. 
     The degradation of the light emitting device is caused by heat generated internally and, oxidation of the device by oxygen and moisture permeated into the device, resulting in a reduction of the light emitting area therein. 
     Such problems are common to active matrix type and passive matrix type light emitting devices. Specially the active matrix type device experiences more heat-related problems than the passive matrix type device. In a device with a larger light emitting area, the center part generates heat of a higher temperature than the outer part. 
       FIG. 1  is a sectional view of a conventional light emitting device. 
     Referring to  FIG. 1 , a light emitting display  100  comprises a pixel circuit part (P) having a first electrode  120 , a light emitting part  130 , and a second electrode  140  formed on a substrate  110 . The first electrode  120  is patterned and insulated by an insulating layer. The organic light emitting part  130  is formed on the first electrode  120 , while the second electrode  140  is formed on the light emitting part  130 . The substrate  110  is covered with a shield cap  160  and is sealed with a sealant  170  to protect the pixel circuit part (P) from oxygen and moisture permeated into the device. 
     An getter  150  is inserted into the display  110  for absorption from moisture and/or oxygen. A heat sink  180  is adhered to an outer surface of a shield cap  160  by adhesive  185  for preventing degradation of the display  100  by heat 
     However, since a light emitting display  100  as above is relying solely on the heat sink  180 , its capacity to discharge heat generated in the pixel circuit part (P) is very limited. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art. 
     In one aspect of the present invention, there is provided a light emitting display comprising a pixel circuit part including a first electrode formed on a substrate, a light emitting part formed on the first electrode, and a second electrode formed on the light emitting part; a spacer positioned within the pixel circuit part, and formed on the substrate to protrude higher than the light emitting part; and a shield cap formed on or over the spacer. 
     In another aspect of the present invention, there is provided a light emitting display comprising a substrate; an emissive area comprising a first electrode patterned on the substrate; a light emitting part formed on the substrate; a second electrode formed on the light emitting part; a spacer formed between the substrate and the second electrode to protrude higher than the light emitting part; and a shield cap formed to be in contact with the surface of the second electrode. 
     The spacer positioned at a central part of the pixel circuit part is larger-sized than a spacer positioned at a peripheral part. 
     The spacer at a central part of the pixel circuit part can be relatively larger in number than a spacer at a peripheral part. 
     The spacer can be disposed in various size, number, and shape depending on positions of the pixel circuit part. 
     The second electrode formed on the spacer is in contact with the inner surface of the shield cap. 
     A metal layer is formed on the second electrode, which second electrode being formed on the spacer, and the metal layer is in contact with the inner surface of the shield cap. 
     A getter unit is formed either on the second electrode, or on the second electrode formed on the spacer, or on both. 
     The getter unit formed over the spacer is in contact with the inner surface of the shield cap. 
     One or more of a heat sink and a cooling fan can be additionally formed at outter side of the sheild cap. 
     The area in which the light emitting part is formed can be emissive area, and the other areas can be nonemissive areas. 
     The getter unit can be of a thin film type. 
     One or more of the spacer, the shield cap, the heat sink, and the cooling fan can be made metal with a high thermal conductivity. 
     The spacer is formed either at areas where a thin film transistor, or a storage capacitor is positioned, when the light emitting display is of passive matrix type, while the spacer is formed either at areas where an insulating layer, or barrier rib is formed, or at both, when the light emitting display is of active matrix type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements. 
         FIG. 1  is a sectional view of a conventional light emitting display. 
         FIG. 2  is a sectional view of a light emitting display according to a first embodiment of the present invention. 
         FIG. 3  is a exploded view of part “B” in  FIG. 2 . 
         FIG. 4  is a sectional view of a light emitting display according to a second embodiment of the present invention. 
         FIG. 5  is a sectional view of a light emitting display according to a third embodiment of the present invention. 
         FIG. 6  is a sectional view of a light emitting display according to a fourth embodiment of the present invention. 
         FIG. 7  illustrates a panel showing examples of spacer positions in the above embodiments of the present invention. 
         FIGS. 8   a  to  8   h  illustrate examples of the spacer in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings. 
     First Embodiment 
       FIG. 2  is a sectional view of a light emitting display according to the first embodiment of the present invention, and  FIG. 3  is a exploded view of part “B” in  FIG. 2 . 
     Referring to  FIG. 2 , a light emitting display  200  according to the first embodiment of the present invention comprises a first electrode  220  formed on a substrate  210 . The first electrode  220  is patterned and insulated by an insulating layer  222 . An organic light emitting part  230  is formed on the first electrode  220 , and a second electrode  240  is formed on the light emitting part  230 , whereby a pixel circuit part (P) is formed. A getter  250  is adhered to the substrate  210 , and a shield cap  260  is adhered to the substrate  210  and sealed with a sealant  270  to protect the pixel circuit part (P) from oxygen and moisture that permeates from the outside of the shield cap  260 . 
     A spacer  224  is formed between the substrate  210  and the second electrode  240  to protrude higher than the light emitting part  230 . Accordingly, the second electrode  240  can be classified into a first part  240   a  formed over the spacer  224  and a second part  240   b  formed on the light emitting part  230 . 
     As a result, the first part  240   a  of the second electrode  240  formed on the spacer  224  is in contact with the inner surface of the shield cap  260 . Thus, it can easily discharge heat generated by the light emitting part  230  in the pixel circuit part (P). 
     The spacer  224  can be formed on the insulating layer  222 . The area in which the insulating layer  222  is formed is classified as nonemissive area, while the area in which the light emitting part  230  is formed to emit light toward outside is classified as emissive area. 
     Referring to  FIG. 3  which is a exploded view of part “B” in  FIG. 2 , the spacer  224  formed on the insulating layer  222  is pillar-shaped such that the first art  240   a  of the second electrode  240  can be in contact with the inner surface of a shield cap  260 , whereby the heat generated in the pixel circuit part (P) can be easily be discharged. Further, since the spacer  224  is structured to support the shield cap  260 , the display  200  is protected from external force. 
     In addition, if the spacer  224  is made of a metal having a high thermal conductivity (e.g., aluminum (Al), copper (Cu), argentum (Ag), etc.), the heat generated internally can be transferred to the shield cap  260  through the pillar-shaped spacer  224 . Furthermore, the space formed between the shield cap  260  and substrate  210  by the spacer  224  can enhance circulation and discharge of heat generated internally. 
     Although the light emitting display  200  as shown in  FIGS. 2 and 3  is the passive matrix type, the present invention is not limited thereto, but rather, is applicable to both the passive and the active matrix types. A more detailed description thereon is given below. 
     The spacer  224  can be formed either at areas where an insulating layer, or a barrier rib of the nonemissive area is formed, or at both, when the light emitting display  200  is the passive matrix type. 
     The spacer  224  can be formed either at areas where a thin film transistor, or a storage capacitor is positioned, or at both, when the light emitting display is the active matrix type. 
     However, positions of the spacers  224  are not limited thereto, but rather, the spacers  224  can be formed anywhere other than light emitting areas when they can effectively discharge the heat 
     Although not shown in the drawings, the spacer  224  can also be formed such that upper part thereof is in contact with the inner surface of the shield cap  260  without forming the first part  240   a  of the second electrode  240  at the upper part thereof. 
     Second Embodiment 
       FIG. 4  is a sectional view of a light emitting display according to the second embodiment of the present invention. 
     Referring to  FIG. 4 , a light emitting display  400  according to the second embodiment of the present invention comprises a first electrode  420  formed on a substrate  410 . The first electrode  420  is patterned and insulated by an insulating layer  422 . An organic light emitting part  430  is formed on the first electrode  420 , and a second electrode  440  is formed over the light emitting part  430 , whereby a pixel circuit part (P) is formed. A getter unit  450  is adhered to the second electrode  440 , and a shield cap  460  is adhered to the substrate  410  and sealed with a sealant  470  to improtect the pixel circuit part (P) from oxygen and moisture that permeates from the outside of the shield cap  260 . 
     A spacer  424  is formed between the substrate  410  and the second electrode  440  to protrude higher than the light emitting part  430 . Accordingly, the second electrode  440  can be classified into a first part  440   a  formed over the spacer  424  and a second part  440   b  formed on the light emitting part  430 . 
     Here, the getter unit  450  is adhered to the second part  440   b  of the second electrode  440  formed on the light emitting part  430 , and a metal layer  490  is formed on the first art  440   a  of the second electrode  440  formed on the spacer  424 . 
     Accordingly, the heat generated from the light emitting part  430  in the pixel circuit part (P) can easily be discharged by the first art  440   a  of the second electrode  440  formed on the spacer  424 , through the metal layer  490  and the shield cap  460 , the inner surface of the shield cap  460  being in contact with the metal layer  490 . 
     The spacer  424  can be formed on the insulating layer  422 , and the area in which the insulating layer  422  is formed is classified as nonemissive area, while the area in which the light emitting part (P) is formed to emit light toward outside is classified as emissive area. 
     In detail, the spacer  424  formed on the insulating layer  422  is pillar-shaped such that the metal layer  490  formed on the second electrode  440   a  can be in contact with the shield cap  460 , thereby easily discharging heat generated within the pixel circuit part (P). Further, the spacer  424  can be structured to support the shield cap  460 , and protect the device from external force. 
     In addition, if the spacer  424  is made of a metal having a high thermal conductivity (e.g., aluminum (Al), copper (Cu), argentum (Ag), etc.), the heat generated internally can be transferred to the shield cap  460  through the pillar-shaped spacer  424 . Furthermore, the space formed between the shield cap  460  and substrate  410  can enhance circulation and discharge of the generated heat 
     Although the light emitting display  400  as shown in  FIG. 4  of the passive matrix type, the present invention is not limited thereto, but rather, is applicable to both the passive and the active matrix types. A more detailed description thereon is given below. 
     The spacer  424  can be formed either at areas where an insulating layer, or barrier rib is formed, or at both, when the light emitting display  400  is the passive matrix type. 
     The spacer  424  can be formed either at areas where a thin film transistor, or a storage capacitor is positioned, when the light emitting display  400  is of an active matrix type. 
     However, position of the spacer  424  is not limited thereto, but rather, it can be formed anywhere other than light emitting areas, when they can effectively discharge the heat. And the metal layer  490  is not limited to a specific material. 
     Third Embodiment 
       FIG. 5  is a sectional view of a light emitting display according to the third embodiment of the present invention. 
     Referring to  FIG. 5 , a light emitting display  500  according to the third embodiment of the present invention comprises a first electrode  520  formed on a substrate  510 . The first electrode  520  is patterned and insulated by an insulating layer  522 . An organic light emitting part  530  is formed on the first electrode  520 , and a second electrode  540  is formed over the light emitting part  530 , whereby a pixel circuit part (P) is formed. A getter unit  550  is adhered to the second electrode  540 , and a shield cap  560  is adhered to the substrate  510  and sealed with a sealant  570  to protect the pixel circuit part (P). 
     A spacer  524  is formed between the substrate  510  and the second electrode  540  to protrude higher than the light emitting part  530 . Accordingly, the second electrode  540  can be classified into a first part  540   a  formed on the spacer  524  and a second part  540   b  formed on the light emitting part  530 . 
     Here, the getter unit  550  is formed either on the second electrode  540   b , or up to the upper part of the spacer  524 , and a metal layer  590  is formed on upper part of the second electrode  540   a.    
     Accordingly, the heat generated by the light emitting part  530  in the pixel circuit part (P) can easily be discharged by the first part  540   a  of the second electrode  540  formed on the spacer  524 , through the metal film  590  and the shield cap  560 , the inner surface of the shield cap  560  being in contact with the metal layer  590 . 
     Furthermore, the thin film type getter  550  formed on the second art  540   b  of the second electrode  540  can serve as a protective film for directly cutting off an heating by which a device in the pixel circuit part (P) is degraded by moisture or oxygen. 
     The spacer  524  can be formed on the insulating layer  522 , and the area in which the insulating layer  522  is formed is classified as nonemissive area, while the area in which the light emitting part is formed and light is emitted is classified as emissive area. 
     In detail, the spacer  524  formed on the insulating layer  522  is pillar-shaped such that the metal layer  590  formed on the first part  540   a  of the second electrode  540  can be in contact with the shield cap  560 , thereby easily discharging heat generated within the pixel circuit part (P). Further, the spacer  524  can be structured to support the shield cap  560 , and protect the device from external pressure. 
     In addition, if the spacer  524  is made of a metal having a high thermal conductivity (e.g., aluminum (Al), copper (Cu), argentum (Ag), etc.), the heat generated internally can be transferred to the shield cap  560  through the pillar-shaped spacer  524 . Furthermore, the space between the shied cap  560  and the substrate  510  by the spacer  524  can enhance circulation and discharge of heat generated internally. 
     Although the light emitting display as shown in  FIG. 5  is the passive matrix type, the present invention is not limited thereto, but rather, is applicable to both the passive and the active matrix types. A more detailed description thereon is given below. 
     The spacer  524  can be formed either at areas where an insulating layer, or barrier rib is formed, or at both, when the light emitting display is of the passive matrix type. 
     The spacer  524  can be formed either at areas where a thin film transistor, or a storage capacitor is positioned, when the light emitting display is the active matrix type. 
     However, position of the spacer  524  is not limited thereto, but rather, it can be formed anywhere other than light emitting areas, when they can effectively discharge the heat. And the metal layer  590  is not limited to a specific material. 
     Fourth Embodiment 
       FIG. 6  is a sectional view of a light emitting display according to the fourth embodiment of the present invention. 
     Referring to  FIG. 6 , a light emitting display  600  according to the fourth embodiment of the present invention comprises a first electrode  620  formed on a substrate  610 . The first electrode  620  is patterned and insulated by an insulating layer  622 . An organic light emitting part  630  is formed on the first electrode  620 , and a second electrode  640  is formed over the light emitting part  630 , whereby a pixel circuit part (P) is formed. A getter unit  650  is adhered to the second electrode  640 , and a shield cap  660  is adhered to the substrate  610  and sealed with a sealant  670 . 
     A spacer  624  is formed between the substrate  610  and the second electrode  640  to protrude higher than the light emitting part  630 . Accordingly, a second electrode  640  can be classified into a first part  640   a  formed over the spacer  624  and a second part  640   b  formed on the light emitting part  630 . 
     Here, the getter  650  can be formed at one side of the substrate  610 , or, although not shown in the drawing, at one side of the shield cap  660 . 
     On the other hand, one or more of a heat sink or a cooling fan can be adhered to an outer side of the shield cap  660 , using an adhesive  685 , etc. with excellent thermal conductivity. 
     Accordingly, the heat generated by the light emitting part  630  in the pixel circuit part (P) can easily be discharged by the first part  640   a  of he second electrode  640  formed to contact the shield cap  660  over the spacer  624 , through the shield cap  660 , the shield cap  660  being in surface contact with the lint part  640   a  of the second electrode  640 . Also, the heat sink or cooling fan  680  formed at outer side of the shield cap  660  can contribute to quickly reduce the heat generated in the pixel circuit portion (P). 
     The spacer  624  can be formed on the insulating layer  622 , and the area in which the insulating layer  622  is formed is classified as nonemissive area, while the area in which the light emitting part is formed to emit light is classified as emissive area. 
     In detail, the spacer  624  formed on the insulating layer  622  is pillar-shaped such that a metal layer (not shown) formed on the first part  640   a  of the second electrode  640  can be in contact with the shield cap  660 , whereby easily discharging the heat generated in the pixel circuit part (P). Further, the spacer  624  can be structured to support the shield cap  660 , and protect the device from external force. The heat sink or cooling fan  680  can reduce the generated heat more quickly. 
     In addition, if the spacer  624 , or the heat sink, or the cooling fan  680  is made of a metal having a high thermal conductivity (e.g., aluminum (Al), copper (Cu), argentum (Ag), etc.), the heat generated internally can be discharged through the spacer  624  as well as the heat sink or the cooling fan  680 . Furthermore, the space between the shield cap  660  and the substrate  610  by the spacer  624  can enhance circulation and discharge of the generated heat. 
     Although the light emitting display as shown in  FIG. 6  is the passive matrix type, the present invention is not limited thereto, but rather, is applicable to both the passive and the active matrix types. A more detailed description thereon is given below. 
     The spacer  624  can be formed either at areas where an insulating layer, or barrier rib is formed, or at both, when the light emitting display is of the passive matrix type. 
     The spacer  624  can be formed either at areas where a thin film transistor, or a storage capacitor is positioned, when the light emitting display is of an active matrix type. 
     However, position of the spacer  624  is not limited thereto, but rather, it can be formed anywhere other than light emitting areas, when they can effectively discharge the heat. And the heat sink or cooling fan  680  is not limited to a specific material. 
       FIGS. 7 to 8   h  show areas where the spacer is positioned in different embodiments of the present invention. 
       FIG. 7  illustrates a panel showing examples of spacer positions in different embodiments of the present invention, and  FIGS. 8   a  to  8   h  illustrate examples of the spacer in  FIG. 7 . 
     As shown in  FIG. 7 , the panel is sectioned in a plurality of areas, and the spacers are differently formed depending on the amount of heat generated from the respective area. 
     As to the temperature distribution on the panel, the central part of the panel has a higher temperature than the outer part due to the more heat generated there, and the temperature becomes lower toward the outer part. Accordingly, the spacers can be formed variously in a manner that a spacer with a larger diameter is formed at the center part, and one with a smaller diameter is formed at the outer part. 
     As shown in  FIG. 8   a , a spacer with the largest diameter  824   a  is formed at the center of the panel  7  where the highest temperature is generated. 
       FIG. 8   b  shows spacers with relatively small diameter  824   b  formed at the peripheries  4 ,  5 ,  9 , and  10  of the central part. 
       FIG. 8   c  shows spacers with diameters of a third dimension  824   c  formed at side central parts  2 ,  6 ,  8 , and  12  of the panel. 
       FIG. 8   d  shows spacers with the smallest diameter  824   d  formed at outermost parts  1 ,  3 ,  11 , and  13 . 
     Referring to  FIGS. 8   e  to  8   h , which show examples in other example embodiments of the present invention, four spacers  824   e  are formed at the central part  7  of  FIG. 8   a  where spacer with the largest diameter  824   a  is formed, and three spacers  824   f  are formed at the peripheries  4 ,  5 ,  9 , or  10  of the center of  FIG. 8   b.    
     Two spacers  824   g  are formed at the side central parts  2 ,  6 ,  8 , and  12  of  FIG. 8   c , and one spacer  824   h  is formed at outermost parts  1 ,  3 ,  11 , and  13  of  FIG. 8   d.    
     In the aforementioned panel temperature distribution, if analysis and measurements are made using simulations, and the spacer is formed in different sizes, positions, shapes, and numbers, the generated heat can be more effectively discharged. In addition, it is more effective, if the number of spacers is gradually reduced for areas having a lower temperature, or the spacer are disposed to maintain up/down and/or left/right balance so that the amounts of generated heat and discharged heat are in balance. 
     As described above, the present invention allows the light emitting devices positioned at the central part and the peripheral part of a panel to uniformly and quickly discharge the generated heat so that deteriorations by heat such as color changes or luminance reduction can be prevented, whereby providing a light emitting display with excellent reliability. 
     The invention being thus described it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.