Patent Publication Number: US-8981364-B2

Title: Organic light emitting diode display

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2013-0062049, filed on May 30, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     1. Field 
     Exemplary embodiments of the present invention relate to an organic light emitting diode display. 
     2. Discussion of the Background 
     An organic light emitting diode display includes two electrodes, and an organic light emitting diode (OLED) interposed therebetween. Electrons injected from a cathode, which is one electrode, and holes injected from an anode, which is the other electrode, are combined in an organic light emitting member to form excitons, and light is emitted while the excitons discharge energy. 
     The cathode and the anode are generally formed of metal, and a display panel having the organic light emitting diode, a sealing member opposed to the display panel to protect the organic light emitting diode of the display panel, and a sealant bonding and sealing the display panel and the sealing member are provided between the cathode and the anode. The cathode is formed on an entire surface of an emission portion (pixel area) and a non-emission portion (spacer formed area) of the display panel, and the anode is formed to correspond to the emission portion. A spacer forming a gap is disposed between the cathode and the anode. 
     A short circuit may be generated by contact between the cathode and the anode due to pressing, cracking, and the like by pressure from outside of the display panel. Such a short circuit may induce local burning of the display, thereby causing a defect of the display. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention 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 
     Exemplary embodiments of the present invention provide an organic light emitting diode display which includes a separate wiring inside a panel in order to inhibit local burning when a short circuit is generated between a cathode and an anode caused by pressure due to external pressure of the display panel. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     An exemplary embodiment of the present invention discloses an organic light emitting diode display including: a display panel; a first electrode disposed in a display area of the display panel and electrically connected to a transistor connected to a gate wiring and a data wiring; a pixel definition film disposed on the display panel, and having an opening through which the first electrode is exposed; organic emission layers disposed on the first electrode; column spacers disposed on non-display areas of the display panel and on the pixel definition layer; a second electrode disposed on the organic emission layers and the column spacers; and signal blocking metal wirings disposed on both side edges of the organic emission layers, and disposed between the first electrode and the second electrode. 
     An exemplary embodiment of the present invention also discloses an organic light emitting diode display, including: a display panel; a first electrode disposed in a display area of the display panel, the first electrode being electrically connected to a transistor, which is connected to a gate wiring and a data wiring; a pixel definition film disposed on the display panel, and including an opening through which the first electrode is exposed; organic emission layers disposed on the first electrode; spacers disposed on non-display areas of the display panel and on the pixel definition layer; a second electrode disposed on the organic emission layers and the spacers; metal wirings disposed on both side edges of the organic emission layers and between the first electrode and the second electrode; and an insulation layer disposed on the metal wirings and configured to prevent an electrical connection between the second electrode and the metal wirings. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a top plan view schematically illustrating an organic light emitting diode display according to an exemplary embodiment of the present invention. 
         FIG. 2  is an enlarged layout view of part “A” illustrated in  FIG. 1 . 
         FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 . 
         FIG. 4  is a top plan view schematically illustrating a structure of a signal blocking metal wiring of the organic light emitting diode display according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
     Further, in the exemplary embodiments, since like reference numerals designate like elements having the same configuration, a first exemplary embodiment is representatively described, and in other exemplary embodiments, only a configuration different from the first exemplary embodiment will be described. 
     It is noted that the drawings are schematically drawn and are not drawn in accordance with a scale. Relative sizes and ratios of parts in the drawings are exaggerated or reduced in their sizes for accuracy and convenience, and a predetermined size is illustrative only, and is not limitative. Further, the same structure, element, or component represented in two or more drawings will be designated by the same reference numerals in order to represent the similar characteristic. It will be understood that when an element is referred to as being “on” or “connected to” another element, it can be directly on or directly connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly on” or “directly connected to” another element, there are no intervening elements present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ) 
     An exemplary embodiment specifically illustrates an exemplary embodiment of the present invention. As a result, various modifications of diagrams are expected. Accordingly, exemplary embodiments are not limited to specific shapes of shown regions, and also include, for example, modifications of the shape by manufacturing 
     Hereinafter, an organic light emitting diode display according to an exemplary embodiment will be described with reference to  FIGS. 1 to 4 . 
       FIG. 1  is a top plan view schematically illustrating the organic light emitting diode display according to an exemplary embodiment,  FIG. 2  is an enlarged layout view of part “A” illustrated in  FIG. 1 , and  FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 .  FIG. 4  is a top plan view schematically illustrating a structure of a signal blocking metal wiring of the organic light emitting diode display according to an exemplary embodiment. 
     As illustrated in  FIG. 1 , an organic light emitting diode display  100  according to an exemplary embodiment includes a display panel  110 , a sealing member  210  for covering the display panel  110 , and a sealant  1  disposed between the display panel and the sealing member  210 . 
     The sealant  1  is disposed along an edge of the sealing member  210 , and the sealant  1  bonds and seals the display panel  110  and the sealing member  210 . Hereinafter, an internal area between the display panel  110  and the sealing member  210  surrounded by the sealant  1  is referred to as a display area DA. Further, pixels are formed in the display area DA to display an image. 
     The sealing member  210  is a smaller size than the display panel  110 . Further, a driver  2  may be mounted in an edge of one side of the display panel  110  which is not covered by the sealing member  210 . 
     Conductive wirings  3  electrically connecting the driver  2  and elements formed inside a space sealed by the sealant  1  are formed at the edge of the display panel  110 . Accordingly, the conductive wirings  3  may be formed to partially overlap the sealant  1 . 
     As illustrated in  FIG. 2 , one pixel may include a red R, green G, and blue B organic emission layer  230 , and column spacers  330  are formed on a pixel definition layer  310  in a non-display area  325  along opposing sides of each organic emission layer  230  area. Further, signal blocking metal wirings  320  are commonly formed to overlap opposing sides of the organic emission layer  230 . 
     As illustrated in  FIG. 3 , an insulation layer  340  for preventing an electrical connection between a second electrode  240  and the signal blocking metal wiring  320  may be further included on the signal blocking metal wiring  320 . The signal blocking metal wirings  320  commonly formed on the organic emission layers  230  are connected to each other at one side of the non-display areas  325  to be connected to the driver  2 . By this method, the signal blocking metal wirings  320  form a mesh. Further, the signal blocking metal wirings  320  may be formed in a rectangular planar shape. 
     Referring to  FIG. 3 , the display panel  110  includes a switching thin film transistor (not illustrated), a driving thin film transistor  80 , a capacitor element  16 , and an organic light emitting diode  200 , which are formed for each pixel. The display panel  110  further includes gate lines disposed in one direction, data lines insulated from and crossing the gate lines, and a common power line. Here, one pixel may be defined based on a boundary of the gate line, the data line, and the common power line, but is not limited thereto. 
     The organic light emitting diode  200  includes a first electrode  220 , the organic emission layer  230  formed on the first electrode  220 , and the second electrode  240  formed on the organic emission layer  230 . Here, the first electrode  220  is an anode (positive (+) electrode), which is a hole-injection electrode, and the second electrode  240  is a cathode (negative (−) electrode), which is an electron-injection electrode. Holes and electrons are injected into the organic emission layer  230  from the first electrode  220  and the second electrode  240 , respectively, to form excitons. When an exciton transitions from an excited state to a ground state, light emission occurs. 
     The pixel definition layer  310 , having an opening through which the first electrode  220  is exposed, is provided on the display panel  110 . The column spacers  330  may be provided on the pixel definition layer  310  of the non-display areas  325  of the display panel  110 . The second electrode  240  may be disposed while being extended on the organic emission layer  230  and the column spacer  330 . 
     The capacitor element  16  includes a first capacitor plate  12  and a second capacitor plate  14  with an interlayer insulation layer  140  interposed therebetween. Here, the interlayer insulation layer  140  may be a dielectric body. Capacitance is determined by the charge stored by the capacitor element  16  and a voltage between both the capacitor plates  12  and  14 . 
     The driving thin film transistor  80  applies driving power, which makes the organic emission layer  230  of a selected pixel emit light toward the first electrode  220 . A driving gate electrode  70  is connected with the first capacitor plate  12 . Each of a driving source electrode  50  and the second capacitor plate  14  is connected to the common power line  18 . A driving drain electrode  60  is connected to the first electrode  220  of the organic light emitting diode  200  through an electrode contact hole. 
     The display panel  110  may be formed as an insulation panel formed of glass, quartz, ceramic, plastic, or the like. However, the present invention is not limited thereto. Accordingly, the display panel  10  may also be formed as a metallic panel formed of stainless steel, or the like. 
     A buffer layer  120  is formed on the display panel  110 . The buffer layer  120  prevents impurity elements from permeating a surface of the display panel  110 , and also planarizes a surface thereof. The buffer layer  120  may be formed of various materials capable of performing the aforementioned functions. For example, any one of a silicon nitride (SiN x ) film, a silicon oxide (SiO 2 ) film, and a silicon oxynitride (SiO x N y ) film may be used as the buffer layer  120 . However, the buffer layer  120  is not essential, and may be omitted according to the type and a process condition of the display panel  110 . 
     A driving semiconductor layer  40  is formed on the buffer layer  120 . The driving semiconductor layer  40  is formed of a polycrystalline silicon film. Further, the driving semiconductor layer  40  includes a channel area  10 , in which an impurity is not doped, and a source area  20  and a drain area  30  formed by p+ doping both sides of the channel area  10 . In this case, the doped ion material is a P-type impurity, such as boron (B), and B 2 H 6  may be used as the doped ion material. Here, the impurity depends on the type of thin film transistor. 
     In an exemplary embodiment, the thin film transistor having a PMOS structure using the P-type impurity is used as the driving thin film transistor  80 , but the present invention is not limited thereto. Accordingly, a thin film transistor having an NMOS structure or a CMOS structure may be used as the driving thin film transistor  80 . Further, the driving thin film transistor  80  may be a polycrystalline thin film transistor including a polycrystalline silicon film. 
     A gate insulation layer  130  formed of silicon nitride (SiN x ), silicon oxide (SiO 2 ), or the like is formed on the driving semiconductor layer  40 . A gate wiring including the driving gate electrode  70  is formed on the gate insulating layer  130 . Further, the gate wiring further includes the gate lines, the first capacitor plate  12 , and other wirings. Further, the driving gate electrode  70  is formed so as to overlap at least part of the driving semiconductor layer  40 , which may include the channel area  10 . 
     The interlayer insulating film  140  covering the driving gate electrode  70  is formed on the gate insulation layer  130 . The gate insulation layer  130  and the interlayer insulation layer  140  commonly have through-holes through which the source area  20  and the drain area  30  of the driving semiconductor layer  40  are exposed. The interlayer insulation layer  140  is formed by using a ceramic based material, such as silicon nitride (SiN x ) or silicon oxide (SiO 2 ), similar to the gate insulation layer  130 . 
     A data wiring, including the driving source electrode  50  and the driving drain electrode  60 , is formed on the interlayer insulation layer  140 . Further, the data wiring further includes the data lines, the common power line  18 , the second capacitor plate  14 , and other wirings. Further, the driving source electrode  50  and the driving drain electrode  60  are connected to the source area  20  and the drain area  30  of the driving semiconductor layer  40  through the through-holes formed on the interlayer insulation layer  140  and the gate insulation layer  130 , respectively. 
     As described above, the driving thin film transistor  80 , including the driving semiconductor layer  40 , the driving gate electrode  70 , the driving source electrode  50 , and the driving drain electrode  60 , is formed. The configuration of the driving thin film transistor  80  is not limited to the aforementioned example, and may be variously modified to well-known configurations easily implementable by those skilled in the art. 
     A planarization film  150  covering the data wiring is formed on the interlayer insulation layer  140 . The planarization film  150  serves to remove a step and planarize the interlayer insulation layer  140  in order to improve efficiency of light emission of the organic light emitting diode  200  to be formed on the planarization film  150 . Further, planarization film  150  has an electrode contact hole through which a part of the driving drain electrode  60  is exposed. 
     The planarization film  150  may be formed of any one of an acrylates resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimides resin, an unsaturated polyester resin, a poly phenylene resin, a poly phenylenesulfide resin, and a benzocyclobutene (BCB) resin. 
     Further, exemplary embodiments are not limited to the aforementioned structure, and any one of the planarization film  150  and the interlayer insulation layer  140  may also be omitted. 
     The first electrode  220  of the organic light emitting diode  200  is formed on the planarization film  150 . That is, the organic light emitting diode display  100  includes each of the first electrodes  220  disposed at each of the pixels, respectively. In this case, the first electrodes  220  are spaced apart from each other. The first electrode  220  is connected to the driving drain electrode  60  through the electrode contact hole in the planarization film  150 . 
     The pixel definition layer  310  having the opening through which the first electrode  220  is exposed is formed on the planarization film  150 . That is, the pixel definition layer  310  has the opening formed at each pixel. Further, the first electrode  220  is disposed to correspond to the opening of the pixel definition layer  310 . However, the first electrode  220  need not be disposed only at the opening of the pixel definition layer  310 , but may be disposed under the pixel definition layer  310  so that part of the first electrode  220  overlaps the pixel definition film  310 . The pixel definition layer  310  may be formed of a resin, such as a polyacrylate resin or a polyimide resin, or a silica-based inorganic material. 
     The organic emission layer  230  is formed on the first electrode  220 , and the second electrode  240  is formed on the organic emission layer  230 . As described above, the organic light emitting diode  200 , including the first electrode, the organic emission layer  230 , and the second electrode  240 , is formed. 
     The organic emission layer  230  is formed of a low molecular organic material or a high molecular organic material. Further, the organic emission layer  230  may be formed of a multiple layers including one or more of the emission layer, the hole-injection layer (HIL), a hole-transporting layer (HTL), an electron-transporting layer (ETL), and the electron-injection layer (EIL). In a case where the organic emission layer  230  includes all of the layers, the hole-injection layer (HIL) is disposed on the first electrode  220 , which is the anode, and the hole-transporting layer (HTL), the emission layer, the electron-transporting layer (ETL), and the electron-injection layer (EIL) are sequentially stacked thereon. 
     In  FIG. 3 , the organic emission layer  230  is disposed only inside the opening of the pixel definition layer  310 , but exemplary embodiments are not limited thereto. Accordingly, the organic emission layer  230  may be formed on the first electrode  220  inside the opening of the pixel definition layer  310 , or may be disposed between the pixel definition layer  310  and the second electrode  240 . The organic emission layer  230  may further include several layers, such as the hole-injection layer (HIL), the hole-transporting layer (HTL), the electron-transporting layer (ETL), and the electron-injection layer (EIL), together with the emission layer. In this case, the hole-injection layer (HIL), the hole-transporting layer (HTL), the electron-transporting layer (ETL), and the electron-injection layer (EIL), but not the emission layer, may be formed on not only the first electrode  220 , but also the pixel definition layer  310 , by using an open mask during a manufacturing process, similar to the second electrode  240 . That is, one or more layers among the several layers included in the organic emission layer  230  may be disposed between the pixel definition layer  310  and the second electrode  240 . 
     Each of the first electrode  220  and the second electrode  240  may be formed of a transparent conductive material, or a transflective or reflective conductive material. The organic light emitting diode display  100  may be a top-emission type, a bottom-emission type, or a dual emission type according to the type of material forming the first electrode  220  and the second electrode  240 . 
     Indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium oxide (In 2 O 3 ) may be used as the transparent conductive material. Lithium (Li), calcium (Ca), lithium fluoride/calcium (LiF/Ca), lithium fluoride/aluminum (LiF/Al), aluminum (Al), silver (Ag), magnesium (Mg), gold (Au), or the like may be used as the reflective material and the transflective material. 
     The sealing member  210  is disposed to face the display panel  110  on the second electrode  240 . The sealing member  210  may be formed of a transparent material, such as glass or plastic. The sealing member  210  is bonded to the display panel  110  to be sealed through the sealant  1  (illustrated in  FIG. 1 ) formed along the edge thereof. 
     The signal blocking metal wiring  320  is provided on upper portions of both-side edges of the organic emission layer  230  between the first electrode  220  and the second electrode  240 . The signal blocking metal wirings  320  cut the power applied to the display when a short circuit is generated caused by contact between the first electrode  220  and the second electrode  240  as a result of the column spacer  330  being pressed by external force, and the signal blocking metal wirings  320  may be positioned at both edges of the first electrode  220 . Further, the signal blocking metal wirings  320  may be provided to be in contact with the second electrode  240  at opposing sides of the first electrode  220 . Further, the insulation layer  340  may be further included on the signal blocking metal wiring  320 . That is, the signal blocking metal wiring  320  may be provided to be in contact with the insulation layer  340  at opposing sides of the organic emission layers  230 . 
     The signal blocking metal wirings  320  may be extended in one direction at positions corresponding to the non-display areas  325  of the pixels which overlap the pixel definition layer  310 . Further, the respective extended signal blocking metal wirings  320  are connected to each other at one side of the non-display areas  325  of the pixels disposed at the outermost non-display area  325  within the sealing member  210  to be connected to the driver  2 . When a voltage is applied to the display  100  by a power-on signal of the driver  2  and the first electrode  220  contacts the second electrode  240  because the column spacer  330  is pressed by external pressure or cracks, the power-on signal is blocked through the signal blocking metal wirings  320  to prevent power from being applied to the transistor element  80 . Accordingly, it is possible to prevent a generation of local burning in the display  100  when a short circuit is generated between the first electrode  220  and the second electrode  240 . 
     As illustrated in  FIG. 4 , the signal blocking metal wiring  320  may be formed in a mesh by connecting the portions of wirings extended from the positions corresponding to the non-display areas  325  of the pixels. As illustrated in  FIG. 2 , the mesh-type signal blocking metal wirings  320  are connected to the driver  2 , and may be connected to the driver  2  at both sides of the wirings extended from the positions corresponding to the non-display areas  325  of the pixels of the outermost region. That is, when a short circuit is generated in any one pixel as a result of a collapse of a columnar spacer  330  or the generation of cracks, the power provided by the power-on signal is not directly applied from the driver  2  to the display, and a path of the power-on signal is diverted through a loop, so that the power is cut by a power-off signal, and thus the entire display is not driven. 
     As described above, in the display according to an exemplary embodiment, it is possible to prevent a defect of the organic light emitting diode display by preventing local burning of the display generated when a short circuit is generated between the cathode and the anode because the columnar spacer collapses as a result of an external force applied to the display panel. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.