Abstract:
An organic light emitting display adapted to be connectable to an external circuit board, the organic light emitting display includes a substrate, a plurality of organic light emitting diodes (OLEDs) on the substrate, and a plurality of input pads coupled with the plurality of OLEDs through wiring lines, the plurality of input pads being connectable to the external circuit board, wherein at least one of the plurality of input pads includes a lead unit extending from a respective one of the wiring lines, and a contact unit contacting the circuit board, and a resistor coupled between the lead unit and the contact unit of the at least one input pad including the lead unit and the contact unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments relate to organic light emitting displays. More particularly, embodiments relate to organic light emitting displays including electrostatic discharge (ESD) protection such that the organic light emitting display may be protected against ESD. 
         [0003]    2. Description of the Related Art 
         [0004]    In general, an organic light emitting display has a self-emission characteristic, larger viewing angle, improved contrast, improved response speed, and lower power consumption than liquid crystal displays (LCDs). Organic light emitting displays do not require a back light, and may be lighter and thinner than LCDs. 
         [0005]    Organic light emitting displays generally include a substrate having a pixel region and a non-pixel region, and a container or an encapsulation substrate. The container or the encapsulation substrate may face the substrate so as to encapsulate the substrate, and may be attached to the substrate by a sealant, e.g., epoxy. 
         [0006]    A plurality of organic light emitting diodes (OLEDs) coupled between scan lines and data lines, and arranged in a matrix manner, form pixels in the pixel region of the substrate. Portions of scan lines and data lines extending from the scan lines and the data lines of the pixel region, power source supply lines for operating the OLEDs, and a scan driver and a data driver for processing external signals supplied through input pads and supplying the processed signals to the scan lines and the data lines are formed in the non-pixel region. 
         [0007]    A film-shaped flexible printed circuit (FPC) (not shown) is electrically coupled with the pad of the organic light emitting display having the above structure. 
         [0008]    Signals, e.g., power source voltages, scan signals, and data signals, are input from the outside through the FPC. 
         [0009]    When the signals are input, via the input pads, to the power source supply lines, the scan driver, and the data driver, the scan driver and the data driver respectively supply the scan signals and the data signals to the scan lines and the data lines. The OLEDs of the pixels selected by the scan signals emit light corresponding to the data signals. 
         [0010]    Since the substrate of the organic light emitting display is formed of glass, a relatively large amount of electrostatic discharge (ESD) is generated during manufacturing and/or operation of the organic light emitting display. If the OLEDs and/or driving circuits, which operate at high speed and at a low voltage, are subjected to such ESD, the OLEDs and/or the driving circuits can erroneously operate and/or can be damaged due to the electric influence. When the driving circuits are subjected to the externally generated ESD through internal signal lines, operation of the driving circuits can be instantaneously stopped. As an amount and/or number of occurrences of ESD generation and/or the voltage increases, circuit wiring lines are more likely to be broken or shorted. In general, the driving circuits are more severely damaged by such ESD as the driving circuits are highly integrated (minimized). 
       SUMMARY OF THE INVENTION 
       [0011]    Embodiments of the invention are therefore directed to organic light emitting displays, which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art. 
         [0012]    It is therefore a feature of an embodiment of the invention to provide organic light emitting displays capable of effectively preventing and/or reducing electrostatic discharge (ESD) from being received through input pads. 
         [0013]    At least one of the above and other features and advantages of the invention may be realized by providing an organic light emitting display adapted to be connectable to an external circuit board, the organic light emitting display including a substrate, a plurality of organic light emitting diodes (OLEDs) on the substrate, and a plurality of input pads coupled with the plurality of OLEDs through wiring lines, the plurality of input pads being connectable to the external circuit board, wherein at least one of the plurality of input pads includes a lead unit extending from a respective one of the wiring lines, and a contact unit contacting the circuit board, and a resistor coupled between the lead unit and the contact unit of the at least one input pad including the lead unit and the contact unit. 
         [0014]    The organic light emitting display may include driving circuits coupled between the wiring lines and the OLEDs. 
         [0015]    The organic light emitting display may include thin film transistors (TFT) coupled between the driving circuits and the OLEDs. 
         [0016]    The resistor may include polysilicon. 
         [0017]    An insulating layer may be arranged between the at least one input pad and the resistor, and wherein the resistor is coupled with the contact unit and the lead unit through contact holes formed in the insulating layer. 
         [0018]    The circuit board may be a flexible printed circuit (FPC). 
         [0019]    When the organic light emitting display is connected to the external circuit board, the contact unit may contact the external circuit board. 
         [0020]    When the organic light emitting display is connected to the external circuit board, the contact unit and the lead unit may contact the external circuit board. 
         [0021]    The lead unit and the contact unit of the at least one input pad may be spaced apart from each other. 
         [0022]    Each of the plurality of input pads may include a lead unit and a contact unit, the lead unit being spaced apart from the corresponding contact unit. 
         [0023]    The resistor may be directly coupled between and may directly contact the lead unit and the contact unit of the at least one of the plurality of input pads. 
         [0024]    The resistor may include a same material as, and may correspond to a same layer as, source and/or drain regions of the OLEDs. 
         [0025]    At least one of the above and other features and advantages of the invention may be realized by providing an organic light emitting display adapted to be connectable to an external circuit board, the organic light emitting display including a substrate, a plurality of organic light emitting diodes (OLEDs) on the substrate, and a plurality of input pads coupled with the plurality of OLEDs through wiring lines, the plurality of input pads being connectable to the external circuit board, wherein each of the plurality of input pads includes a lead unit extending from a respective one of the wiring lines, and a contact unit contacting the circuit board, the lead unit being spaced apart from the contact unit. 
         [0026]    When the organic light emitting display is connected to the external circuit board, the circuit board may contact the contact unit and the lead unit of the respective input pads. 
         [0027]    A resistor may be coupled between the lead unit and the contact unit of each of the input pads. 
         [0028]    The organic light emitting display may include an insulating layer between the lead unit and the contact unit of each of the input pads. 
         [0029]    The lead units and the contact units may include a same material and correspond to a same layer as source, drain, anode and/or cathode electrodes of the OLEDs. 
         [0030]    The input pads may be arranged along an edge portion of the substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
           [0032]      FIG. 1  illustrates a plan view of an organic light emitting display according to an embodiment of the present invention; 
           [0033]      FIG. 2  illustrates a cross-sectional view of the organic light emitting diode (OLED) of  FIG. 1 ; 
           [0034]      FIG. 3  illustrates a plan view of exemplary input pads of  FIG. 1 ; 
           [0035]      FIG. 4  illustrates a cross-sectional view taken along line I 1 -I 2  of  FIG. 3 ; 
           [0036]      FIG. 5  illustrates a plan view of the exemplary input pads of  FIGS. 1 and 3  in a state in which a circuit board contacts respective contact units of the input pads; 
           [0037]      FIG. 6  illustrates a cross-sectional view taken along line I 11 -I 12  of  FIG. 5 ; and 
           [0038]      FIG. 7  illustrates a plan view of the exemplary input pads of  FIGS. 1 and 3  in a state in which a circuit board contacts contact units and lead units of the input pads. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Korean Patent Application No. 10-2007-0106122, filed on Oct. 22, 2007, in the Korean Intellectual Property Office, and entitled: “Organic Light Emitting Display,” is incorporated by reference herein in its entirety. 
         [0040]    Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0041]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when an element is referred to as being “between” two elements, it can be the only element between the two layers, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout the specification. 
         [0042]      FIG. 1  illustrates a plan view of an organic light emitting display according to an exemplary embodiment the invention. 
         [0043]    Referring to  FIG. 1 , the organic light emitting display may include a substrate  100 , scan lines  122 , data lines  124 , and organic light emitting diodes (OLEDs)  120 , coupled between the scan lines  122  and the data lines  124 , in a matrix arrangement. Each of the OLEDs  120 , and respective portions of corresponding ones of the scan lines  122 , and the data lines  124 , may form pixels. 
         [0044]    The substrate  100  may include a pixel region  114  and a non-pixel region  116 . The scan lines  122  and the data lines  124  may extend across the pixel region  114  and the non-pixel region  116 . In the non-pixel region  116 , respective portions of the scan lines  122  and the data lines  124 , power source supply lines (not shown) for operating the OLEDs  120 , a scan driver  130 , and a data driver  140  may be formed. The scan driver  130  and the data driver  140  may process external signals supplied through input pads  126 , and may supply the processed signals to the scan lines  122  and the data lines  124 , respectively. 
         [0045]    In a passive matrix type organic light emitting display, the OLEDs  120  may be coupled between the scan lines  122  and the data lines  124  in a matrix arrangement. In an active matrix type organic light emitting display, the OLEDs  120  may be coupled between the scan lines  122  and the data lines  124  in a matrix arrangement together with thin film transistors (TFTs) (not shown) and capacitors (not shown). The TFTs may control operations of the OLEDs  120  and the capacitors may function to maintain signals. 
         [0046]    The scan driver  130  and the data driver  140  may be formed on the non-pixel region  116  of the substrate  100 . In some embodiments, the scan driver  120  and the data driver  140  may be manufactured during processing of the OLEDs  120 . In some embodiments, the scan driver  120  and the data driver  140  may be manufactured as an additional integrated circuit semiconductor chip to be attached to the substrate  100 , e.g., via a chip on glass (COG) method or a wire bonding method, and electrically coupled with the scan lines  122  and the data lines  124 . 
         [0047]      FIG. 2  illustrates a cross-sectional view of the OLED  120  of  FIG. 1 , in which an example of the active matrix type OLED is schematically illustrated. 
         [0048]    Referring to  FIG. 2 , the OLED may include a buffer layer  101 , a semiconductor layer  102 , a gate insulating layer  103 , a gate electrode  104 , an interlayer insulating layer  105 , source and drain electrodes  106   a  and  106   b,  a planarizing layer  107 , an anode electrode  108 , a pixel defining layer  109 , an organic thin layer  110 , and a cathode electrode  111 . 
         [0049]    The buffer layer  101  may be formed on the substrate  100 . The semiconductor layer  102  may be formed on the buffer layer  101 . The semiconductor layer  102  may provide an active layer. More particularly, the semiconductor layer  102  may provide source, drain, and channel regions of the TFTs. The gate insulating layer  103  may be formed on a top surface of the buffer layer  101  and may cover the semiconductor layer  102 . 
         [0050]    The gate electrode  104  may be formed on the gate insulating layer  103  formed on the semiconductor layer  102 . The interlayer insulating layer  105  may be formed on the gate insulating layer  103  and may cover the gate electrode  104 . Contact holes may be formed in the interlayer insulating layer  105  and the gate insulating layer  103  to expose predetermined parts of the semiconductor layer  102 . The source and drain electrodes  106   a  and  106   b  may be coupled with the semiconductor layer  102  through the contact holes formed on the interlayer insulating layer  105 . 
         [0051]    The planarizing layer  107  may be formed on the interlayer insulating layer  105  to cover the source and drain electrodes  106   a  and  106   b.  A via hole may be formed in the planarizing layer  107  so that the source or drain electrode  106   a  or  106   b  may be exposed. The anode electrode  108  may be coupled with the source or drain electrode  106   a  or  106   b  through the via hole and may be formed on the planarizing layer  107 . The pixel defining layer  109  may be formed on the planarizing layer  107 . The pixel defining layer  109  may be patterned to expose the anode electrode  108 . 
         [0052]    The organic thin layer  110  and the cathode electrode  111  may be formed on the anode electrode  108 . More particularly, the organic thin layer  110  and the cathode electrode  111  may be formed on the exposed portion of the anode electrode  108 . The organic thin layer  110  may be formed to have a structure in which a hole transport layer, an organic light emitting layer, and an electron transport layer are laminated together. The organic thin layer  110  may further include a hole injection layer and an electron injection layer. 
         [0053]      FIG. 3  illustrates an enlarged plan view of a portion of the organic light emitting display including the input pads  126 .  FIG. 4  illustrates a cross-sectional view taken along line I 1 -I 2  of  FIG. 3 .  FIG. 5  illustrates a plan view of exemplary input pads  126  of  FIG. 3  in a state in which the external circuit board  300  overlaps and contacts contact portions  126   b  of the input pads  126 , and  FIG. 6  illustrates a cross-sectional view taken along line I 11 -I 12  of  FIG. 5 . 
         [0054]    Referring to  FIG. 3 , the input pads  126  may be arranged on the substrate  100  by a predetermined distance. The input pads  126  may be coupled with driving circuits of the scan driver  130  and the data driver  140  through wiring lines  128 . 
         [0055]    As discussed above, in organic light emitting displays, the input pads  126  may be formed at an edge portion of the substrate  100 , and may be vulnerable to electrostatic discharge (ESD). 
         [0056]    In some embodiments of the invention, resistors  200  for preventing and/or reducing over-current from instantaneously flowing due to the ESD may be included in the input pads  126  and/or the input pads  126  may include a plurality of portions, e.g., lead units  126   a  and contact units  126   b.  More particularly, in some embodiments, e.g., the input pads  126  may include lead units  126   a  that extend from the wiring lines  128  and contact units  126   b.  The contact units  126   b  may contact pads of an external circuit board  300  (shown in  FIGS. 5 and 7 ). Corresponding pairs of the lead and contact units  126   a,    126   b  may correspond to a respective one of the input pads  126 . Further, the lead unit  126   a  and the corresponding contact unit  126   b  may be spaced apart from each other, as shown, e.g., in  FIGS. 3 and 4 . 
         [0057]    The resistors  200  may be coupled between the lead units  126   a  and the contact units  126   b.  The resistors  200  may be formed of a conductive material, e.g., polysilicon. The resistors  200  may be coupled with the lead units  126   a  and the contact units  126   b  through contact holes  240 . 
         [0058]    Referring to  FIG. 4 , the resistor  200  may be formed on the substrate  100 . The resistor  200  may be formed of, e.g., polysilicon doped to have a predetermined resistance value. An insulating layer  220  may be formed on the substrate  100  where the resistor  200  is formed. The lead units  126   a  and the contact units  126   b  may be formed to be coupled with respective ends of the resistor  200  through contact holes  240  formed in the insulating layer  220 . 
         [0059]    Referring to  FIGS. 2 and 4 , the resistor  200  may be formed of the same material as the semiconductor layer  102 , and may be formed during the process of forming the semiconductor layer  102 . The insulating layer  220  may be formed of the gate insulating layer  103  and/or the interlayer insulating layer  105 . The lead units  126   a  and the contact units  126   b  may be formed of a same electrode material as and during the process of forming the source and drain electrodes  106   a  and  106   b , the anode electrode  108  and/or the cathode electrode  111 . 
         [0060]    In the exemplary embodiment illustrated in  FIG. 5 , the external circuit board  300  does not overlap and/or contact the lead units  126   a  of the input pads  126 . However, embodiments are not limited thereto. 
         [0061]    Referring to  FIGS. 5 and 6 , the circuit board  300 , e.g., an external circuit board, may be coupled with the input pads  126  of the organic light emitting display having the structure illustrated in  FIG. 3 . The circuit board  300  may be formed of a film-shaped FPC. The circuit board  300  may include pads  320 . The pads  320  of the circuit board  300  may contact the contact units  126   b  so that signals, e.g., power source voltages, scan signals, and data signals, may be input from the outside. 
         [0062]    When the signals are input to the power source voltage supply lines, the scan driver  130 , and the data driver  140  through the input pads  126 , the scan driver  130  and the data driver  140  may supply the scan signals and the data signals to the scan lines  122  and the data lines  124 , respectively. Therefore, the OLEDs  120  of the pixels selected by the scan signals may emit light corresponding to the data signals. That is, when a predetermined voltage is applied to the anode electrode  108  and the cathode electrode  111  of the OLEDs  120  selected by the scan signals, holes injected through the anode electrode  108  and electrons injected through the cathode electrode  111  may be re-combined in the organic thin layer  110  to emit light based on a difference in energy generated by this process. Red, green, or blue light may be emitted from each of the pixels in accordance with materials that form the organic light emitting layer of the respective pixel to realize colors of multi-gray scales. 
         [0063]    As described above, in some embodiments of organic light emitting displays according to one or more aspects of the invention, the resistors  200  may be formed in the input pads  126 , which may be vulnerable to ESD. Over-current caused by ESD may be reduced and/or prevented from flowing by the resistors  200 . In some embodiments, all or substantially all of the over-current caused by ESD may be prevented from flowing by the resistors  200 . Only driving signals may be supplied to the organic light emitting display so that the driving circuits and the OLEDs may be safely protected. 
         [0064]    In the exemplary embodiment illustrated in  FIGS. 3 and 4 , the resistors  200  are included in all of the input pads  126 . However, embodiments are not limited thereto. For example, in some embodiments, the resistors  200  may be formed only in some of the input pads  126 . 
         [0065]    Some embodiments may provide organic light emitting displays that may effectively reduce and/or prevent all and/or substantially all ESD from being received to the input pads  126  through the edge of the substrate  100  in a state where the circuit board  300  is not coupled with the input pads  126 . 
         [0066]    Some embodiments may reduce and/or prevent ESD from being received by the substrate  100 , from the outside, including from the circuit board  300 , through the input pads  126  or from being received by the circuit board  300  from the substrate  100  through the input pads  126  in a state where the circuit board  300  is coupled with the input pads  126 . 
         [0067]      FIG. 7  illustrates a plan view of the exemplary input pads  126  of  FIGS. 1 and 3  in a state in which the circuit board  300  contacts and overlaps respective contact units  126   b  and lead units  126   a  of the input pads  126 . 
         [0068]    Although the resistors  200  are included in the exemplary embodiment illustrated in  FIG. 7 , in embodiments in which the pads  320  of the circuit board overlap and/or contact the lead units  126   a  and the contact units  126   b  of the input pads  126 , as shown in  FIG. 7 , the resistors  200  may be omitted. In such embodiments in which the resistors  200  are omitted, it is possible to prevent wiring line resistance from increasing as a result of the resistors  200 . 
         [0069]    In conventional cases in which resistors may be formed between input pads and driving circuits, it is possible to protect the driving circuit from the ESD. However, in such cases, the input pads and the external circuit board may be damaged by the ESD. 
         [0070]    In some embodiments of the invention, resistors may be formed in input pads of an organic light emitting display so that it is possible to prevent and/or reduce over-current caused by ESD received through the substrate or the external circuit board from flowing to the other. More particularly, in some embodiments, input pads may include lead units and contact units, and resistors may be coupled between the respective lead units and the contact units so that it is possible to effectively prevent and/or reduce ESD from being received by the organic light emitting display and/or the external circuit board. In some embodiments, e.g., it is possible to effectively prevent and/or reduce ESD from being received by the input pads at an edge of the substrate in the state where the circuit board is not coupled with the input pads. 
         [0071]    Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.