Organic light emitting display device with an outer circumferentially array of flexible printed circuit board and coupling pads

An organic light emitting display which minimizes the IR drop of voltages supplied to an organic light emitting display panel includes an organic light emitting display panel having a pixel unit on which an image is displayed and first and second power source pads provided at two or more edges outside the pixel unit to receive first and second voltages from at least two directions, and a voltage supplier Flexible Printed Circuit Board (FPCB) including pads electrically coupled to the first and second power source pads and arranged on the outer circumference of the organic light emitting display so as not to overlap with the pixel unit.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for ORGANIC LIGHT EMITTING DISPLAY earlier filed in the Korean Intellectual Property Office on the 18thof January 2008 and there duly assigned Serial No. 10-2008-0005617.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic light emitting display, and more particularly, the present invention relates to an organic light emitting display which minimizes the IR drop of power sources supplying power to an organic light emitting display panel.

2. Description of the Related Art

Among Flat Panel Displays (FPDs), organic light emitting displays display images using Organic Light Emitting Diodes (OLEDs) that generate light by re-combination of electrons and holes. Since an organic light emitting display has a high response speed and low power consumption, organic light emitting displays have been spotlighted as next generation displays.

In general, an organic light emitting display includes a pixel unit including a plurality of pixels, driving circuits for supplying driving signals to the pixel unit, and a power source for supplying power to the pixel unit.

The pixels emit light with a brightness corresponding to data signals supplied in synchronism with scan signals when the scan signals are supplied. The organic light emitting display panel then displays a predetermined image.

In the organic light emitting display, the emission brightness of the pixels is affected by the voltage supplied by the power sources. That is, the output of the power sources determine the emission brightness of the pixels together with the data signals.

Therefore, in order to display an image with uniform picture quality, the power sources must supply the same voltage to the pixels.

However, the power sources are Direct Current (DC) power sources having a predetermined voltage level and a voltage reduction IR drop occurs when a current passes through a power source line.

In particular, since the length of the power source line increases as the size of the display panel of the organic light emitting display increases, a brightness deviation between the pixels increases in accordance with the distance between the pixels and a power source pad that receives the output of the power sources.

Therefore, it is necessary to minimize the voltage reduction IR drop of the power sources.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an organic light emitting display which minimizes the voltage reduction IR drop of the power sources supplying power to an organic light emitting display panel.

In order to achieve the foregoing and/or other objects of the present invention, an organic light emitting display includes an organic light emitting display panel including a pixel unit on which an image is displayed and a plurality of first and second power source pads arranged at two or more edges outside the pixel unit to receive first and second voltages from at least two directions; and a voltage supplier Flexible Printed Circuit Board (FPCB) including a plurality of pads respectively electrically coupled to the first and second power source pads and being arranged on an outer circumference of the organic light emitting display to not overlap the pixel unit.

In addition, the plurality of first power source pads are arranged respectively at a first edge of one side of the organic light emitting display panel and a second edge facing the first edge. The plurality of second power source pads are formed respectively at a third edge of one side of the organic light emitting display panel and a fourth edge facing the third edge.

In addition, the plurality of first and second power source pads are formed at different edges of one side of the organic light emitting display panel.

In addition, each of the plurality of first and second power source pads receives the first and second voltages respectively from both directions of the voltage supplier FPCB.

In addition, a plurality of signal pads for supplying driving signals to the pixel unit are arranged between the plurality of first and second power source pads. The organic light emitting display further includes a driving FPCB electrically coupled to the signal pads and provided independently from the voltage supplier FPCB, and a driving board electrically coupled to the driving FPCB to drive the driving FPCB. Moreover, the driving board is arranged to not overlap the pixel unit. The driving board is electrically coupled to the voltage supplier FPCB to supply the first and second voltages to the voltage supplier FPCB. The driving FPCB includes at least one of a scan driver and a data driver and supplies at least one of a scan signal and a data signal to the pixel unit.

In addition, the pixel unit emits light from both sides thereeof.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, certain exemplary embodiments according to the present invention are described in detail with reference to the accompanying drawings. When a first element is described as being coupled to a second element, the first element may be not only directly coupled to the second element but may also be indirectly coupled to the second element via a third element. Furthermore, some of the elements that are not essential to the complete understanding of the present invention have been omitted for clarity. Also, like reference numerals refer to like elements throughout.

FIG. 1is a block diagram of an example of an organic light emitting display according to an embodiment of the present invention.

Referring toFIG. 1, an organic light emitting display100includes a scan driver110, a data driver120, a timing controller140, a pixel unit150, and a power source130.

The scan driver110generates scan signals to correspond to Scan Control Signals SCSs supplied by the timing controller140. The scan signals generated by the scan driver110are sequentially supplied to scan lines S1to Sn.

The data driver120generates data signals to correspond to Data and Data Control Signals DCSs supplied by the timing controller140. The data signals generated by the data driver120are supplied to data lines D1to Dm in synchronism with the scan signals.

The timing controller140generates the SCSs and the DCSs in response to externally supplied synchronizing signals. The SCSs generated by the timing controller140are supplied to the scan driver110and the DCSs are supplied to the data driver120, in addition, the timing controller140transmits externally supplied Data to the data driver120.

The pixel unit150includes a plurality of pixels160formed in regions partitioned off by the scan lines S1to Sn and the data lines D1to Dm. The pixel unit150displays an image to correspond to the scan signals supplied by the scan driver110and the data signals supplied by the data driver120.

The power source130generates first and second voltages ELVDD and ELVSS using power supplied by an external power supply apparatus (not shown). Then, the power source130supplies the generated first and second voltages ELVDD and ELVSS to the pixel unit150.

In the organic light emitting display100, the pixel unit150is formed in the organic light emitting display panel. The scan driver110and/or the data driver120is mounted on the organic light emitting display panel or an additional Flexible Printed Circuit Board (FPCB). The scan driver110and/or the data driver120can be electrically coupled to the organic light emitting display panel through a pad unit.

In addition, the power source130and/or the timing controller140are mounted on a driving board outside the organic light emitting display panel to be electrically coupled to the organic light emitting display panel and/or the driving FPCBs through a FPCB.

FIG. 2is a circuit diagram of an example of a pixel ofFIG. 1. For convenience sake, inFIG. 2, a pixel is coupled to an nth scan line Sn and an mth data line Dm.

Referring toFIG. 2, a pixel160includes an Organic Light Emitting Diode (OLED), the scan line Sn, the data line Dm, a first voltage line ELVDD, and a pixel circuit162coupled to the OLED.

The anode electrode of the OLED is coupled to the pixel circuit162and the cathode electrode is coupled to the second voltage line ELVSS. The OLED emits light with a brightness corresponding to the amount of current supplied by the pixel circuit162.

The pixel circuit162includes a first transistor M1, a second transistor M2, and a storage capacitor Cst.

The first electrode of the first transistor M1is coupled to the data line Dm, and the second electrode of the first transistor M1is coupled to a first node N1. The gate electrode of the first transistor M1is coupled to the scan line Sn. The first transistor M1is turned on when a scan signal is supplied to the scan line Sn to transmit a data signal supplied to the data line Dm to the first node N1.

The first electrode of the second transistor M2is coupled to the first voltage line ELVDD, and the second electrode of the second transistor M2is coupled to the anode electrode of the OLED. The gate electrode of the second transistor M2is coupled to the first node N1. The second transistor M2controls current that flows from the first voltage line ELVDD to the anode electrode of the OLED to correspond to a voltage supplied to the gate electrode thereof.

One terminal of a storage capacitor Cst is coupled to the first node N1, and the other terminal of the storage capacitor Cst is coupled to the first voltage line ELVDD and the first electrode of the second transistor M2. The storage capacitor Cst stores a voltage corresponding to a data signal supplied to the first node N1when the scan signal is supplied to the scan line Sn and maintains the stored voltage for one frame.

The operation process of the pixel160is described in detail as follows. First, when the scan signal is supplied to the scan line Sn, the first transistor M1is turned on. When the first transistor M1is turned on, the data signal supplied to the data line Dm is transmitted to the first node N1through the first transistor M1. When the data signal is transmitted to the first node N1, a voltage corresponding to a difference between the voltage of the first voltage line ELVDD and the data signal is stored in the storage capacitor Cst. Then, the second transistor M2controls current that flows from the first voltage line ELVDD to the OLED to correspond to a voltage supplied to the gate electrode thereof. Therefore, the OLED emits light with a brightness corresponding to the amount of current supplied thereto to display an image.

As described above, the pixel160emits light with a brightness corresponding to the amount of current supplied by the second transistor M2. The voltage of the first node N I to which the gate electrode of the second transistor M2is coupled is maintained for one frame by the storage capacitor Cst.

The storage capacitor Cst stores a voltage corresponding to a difference between the voltage of the first voltage line ELVDD and the data signal while the data signal is supplied to maintain the voltage for one frame. Therefore, the emission brightness of the pixel160varies in accordance with the voltage of the first voltage line ELVDD and the data signal.

The voltage of the first voltage line ELVDD supplied to the pixels160can vary by the voltage reduction IR Drop which occurs when passing through a power source line. Therefore, the pixels160that receive the same data signal emit light with different brightness so that picture quality can deteriorate.

Therefore, the voltage reduction IR Drop of the first voltage line ELVDD must be minimized.

FIG. 3is an exploded perspective view of an organic light emitting display according to an embodiment of the present invention.FIG. 4is a perspective view of an assembly of the organic light emitting display ofFIG. 3.

InFIGS. 3 to 4, the scan driver and/or the data driver are not mounted on the organic light emitting display panel but are mounted on an additional Flexible Printed Circuit Board (FPCB). However, the present invention is not limited thereto.

Referring toFIGS. 3 and 4, an organic light emitting display includes an organic light emitting display panel300, a voltage supplier FPCB400, and a driving board500. The voltage supplier FPCB400transmits first and second voltages ELVDD and ELVSS to the organic light emitting display panel300. In addition, driving FPCBs510are further coupled between the driving board500and the organic light emitting display panel300.

The organic light emitting display panel300includes a pixel unit310for displaying an image, a plurality of power source pads PELVDDand PELVSSfor respectively supplying voltages ELVDD and ELVSS and driving signals to the pixel unit310, and signal pads320. The power source pads PELVDDand PELVSSand the signal pads320are positioned at edges300ato300dof the organic light emitting display panel300.

The pixel unit310includes a plurality of pixels that are not shown. The pixel unit310displays an image to correspond to the driving signals supplied by the signal pads320and the voltages ELVDD and ELVSS supplied by the power source pads PELVDDand PELVSS.

The pixel unit310may be formed to emit light from both sides thereof. For example, the pixel unit310may include transparent devices formed on a transparent substrate to emit light from both sides. Alternately, the pixel unit310may emit light from sides thereof by including at least two pixel regions to emit light in different directions.

As such, since images can be displayed on both sides of the pixel unit310when the pixel unit310is formed to emit light from the both sides thereof, the utility of the organic light emitting display can be enhanced.

The power source pads PELVDDand PELVSSare distributed and arranged on at least two edges of one outer side of the pixel unit on one side of the organic light emitting display panel300.

In more detail, the power source pads PELVDDand PELVSSinclude first power source pads PELVDDfor receiving first voltages ELVDD and second power source pads PELVSSfor receiving second voltages ELVSS.

Each of the first and second power source pads PELVDDand PELVSSis distributed on at least two edges of one side of the organic light emitting display panel300to receive the first and second voltages ELVDD and ELVSS from both sides of the voltage supplier FPCB400.

For example, a plurality of the first power source pads PELVDDmay be formed at first and second edges300aand300bto face each other on the one side of the organic light emitting display panel300. Accordingly, the first power source pads PELVDDreceive the first voltage ELVDD from both sides and can transmit the same to the pixel unit310.

A plurality of the second power source pads PELVSSmay be formed at third and fourth edges300cand300dto face each other on the one side of the organic light emitting display panel300. Accordingly, the second power source pads PELVSSreceive the second voltage ELVSS from both sides and can transmit the same to the pixel unit310.

That is, the first power source pads PELVDDand the second power source pads PELVSSmay be formed at different edges on the side of the organic light emitting display panel300.

However, the arrangement of the power source pads PELVDDand PELVSSof the present invention is not limited to the above. That is, each of the first and second power source pads PELVDDand PELVSSis arranged in at least three edges on the one side of the organic light emitting display panel300. Accordingly, each of the first and second power source pads PELVDDand PELVSScan receive the first and second voltages ELVDD and ELVSS from at least three directions. In this case, at least some of the first and second power source pads PELVDDand PELVSSmay be formed at the same edge on the one side of the organic light emitting display panel300.

The signal pads320are electrically coupled to the driving FPCB510provided independently from the voltage supplier FPCB400to transmit a driving signal supplied by the driving FPCB510to the pixel unit310. A plurality of the signal pads320may be provided between the first and second power source pads PELVDDand PELVSS. A plurality of the driving FPCBs510may be electrically coupled to the signal pads.

The voltage supplier FPCB400include a plurality of pads P electrically coupled to the first and second power source pads PELVDDand PELVSSof the organic light emitting display panel300. For example, the voltage supplier FPCB400may include the pads P to be overlapped with and electrically coupled to the first and second power source pads PELVDDand PELVSSof the organic light emitting display panel300.

In addition, the voltage supplier FPCB400is electrically coupled to the driving board500through a pad that is not shown. Accordingly, the voltage supplier FPCB400transmits the first and second voltages ELVDD and ELVSS from the driving board500to the organic light emitting display panel300.

To this end, the voltage supplier FPCB400includes lines (not shown) formed in a single layer or multiple layers for supplying the first and second voltages ELVDD and ELVSS. The voltage supplier FPCB400uniformly applies the first and second voltages ELVDD and ELVSS to the entire organic light emitting display panel300through the internal line.

However, in the present invention, the voltage supplier FPCB400is arranged not to be overlapped with the pixel unit310of the organic light emitting display panel300. For example, the voltage supplier FPCB400may be arranged on the outer circumference of the organic light emitting display panel300in the form of surrounding an edge on a side of the organic light emitting display panel300.

In other words, since the voltage supplier FPCB400does not cover the pixel unit310, the image is not disturbed from being displayed even when the pixel unit310emits light from both sides thereof.

The driving board500is electrically coupled to the voltage supplier FPCB400and the driving FPCB510and mounts a power supply and/or a timing controller which are not shown. The driving board500generates the voltages ELVDD and ELVSS and/or a control signal and transmits them to the voltage supplier FPCB400and/or the driving FPCB510.

However, in the present invention, since the driving board500is formed not to be overlapped with the pixel unit310, the image is not disturbed from being displayed even when the pixel unit310emits light from both sides thereof For example, the driving board500may be arranged on the outer circumference of the organic light emitting display panel300in the form of surrounding an edge on a side of the organic light emitting display panel300.

The driving FPCB510may include a scan driver S/D for supplying a scan signal to the pixel unit310and/or a data driver D/D for supplying a data signal to the pixel unit310.

The driving FPCB510is electrically coupled to the driving board500and is driven by the driving board500. That is, the scan driver S/D and/or the data driver D/D which are arranged Ion the driving FPCB510may be driven corresponding to the control signals transmitted from the driving board500.

According to the present invention described above, the power source pads PELVDDand PELVSSof the organic light emitting display panel300are distributed and arranged at two edges. The respective first and second voltages ELVDD and ELVSS are supplied to the organic light emitting display panel300from at least two directions.

Thus, in the organic light emitting display panel300, the IR drop of the first and second voltages ELVDD and ELVSS can be minimized. Therefore, the organic light emitting display panel300can display an image with uniform image quality even in a big size. Accordingly, the organic light emitting display can be applied to various displays such as a TV and a sign board.

In addition, the organic light emitting display device according to the present invention further includes a plurality of pads P electrically coupled to the power source pads PELVDDand PELVSSof the organic light emitting display panel300. In addition, according to the present invention, the voltage supplier FPCB400for supplying the first and second voltages ELVDD and ELVSS to the organic light emitting display panel300through the internal line is additionally provided. The first and second voltages ELVDD and ELVSS can be evenly applied to the organic light emitting display panel300through the internal line of the voltage line supplying FPCB400.

Furthermore, since the voltage supplier FPCB400and the driving board500are designed not to be overlapped with the pixel unit310of the organic light emitting display panel300, the present invention can be usefully applied to a dual type organic light emitting display. Therefore, the utility of an organic light emitting display can be enhanced.