KR100836431B1 - Pixel and organic light emitting display device using the pixel - Google Patents

Abstract

A pixel and an OLED(Organic Light Emitting Display) device using the same are provided to display uniform images by controlling a voltage charged in a storage capacitor in order to compensate for threshold voltages of driving transistors. A pixel includes an organic light emitting diode(OLED), first to fifth transistors(M1,M2,M3,M4,M5) and a storage capacitor(Cst). The second transistor is turned on when scan signals are supplied to scan lines. The first transistor is connected between a second electrode of the second transistor and the organic light emitting diode. The third transistor, which is connected between a gate and a second electrode of the first transistor, is controlled by a light emitting control signal from light emitting control lines. The fourth transistor, which is connected between a first voltage source and a first electrode of the first transistor, is turned on and off alternately with the third transistor. The fifth transistor, which is connected between the first transistor and the organic light emitting diode, is turned off while turning on the second transistor. The storage capacitor is connected between the gate of the first transistor and the first voltage source.

Description

Pixel and Organic Light Emitting Display Device Using the Pixel}

1 is a circuit diagram showing a conventional circuit.

2 is a diagram illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.

3 is a waveform diagram illustrating a driving waveform supplied from the scan driver shown in FIG. 2.

FIG. 4 is a circuit diagram illustrating a first embodiment of the pixel illustrated in FIG. 2.

FIG. 5 is a waveform diagram illustrating a method of driving the pixel illustrated in FIG. 4.

FIG. 6 is a circuit diagram illustrating a second embodiment of the pixel illustrated in FIG. 2.

FIG. 7 is a waveform diagram illustrating a method of driving the pixel illustrated in FIG. 6.

FIG. 8 is a circuit diagram illustrating a third embodiment of the pixel illustrated in FIG. 2.

9 is a waveform diagram illustrating a method of driving the pixel illustrated in FIG. 8.

<Explanation of symbols for main parts of the drawings>

2,142: pixel circuit 4,140: pixel

110: scan driver 120: data driver

130: pixel portion 150: timing controller

The present invention relates to a pixel and an organic light emitting display device using the same, and more particularly, to a pixel and an organic light emitting display device using the same to display an image of uniform brightness and to minimize the number of transistors.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. The flat panel display includes a liquid crystal display, a field emission display, a plasma display panel, and an organic light emitting display.

Among flat panel displays, an organic light emitting display device displays an image using an organic light emitting diode that generates light by recombination of electrons and holes. Such an organic light emitting display device has an advantage of having a fast response speed and being driven with low power consumption.

1 is a circuit diagram illustrating a pixel of a conventional organic light emitting display device.

Referring to FIG. 1, a pixel 4 of a conventional organic light emitting display device is connected to an organic light emitting diode OLED, a data line Dm, and a scanning line Sn to control the organic light emitting diode OLED. The pixel circuit 2 is provided.

The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 2, and the cathode electrode is connected to the second power source ELVSS. Such an organic light emitting diode (OLED) generates light having a predetermined brightness in response to a current supplied from the pixel circuit 2.

The pixel circuit 2 controls the amount of current supplied to the organic light emitting diode OLED corresponding to the data signal supplied to the data line Dm when the scan signal is supplied to the scan line Sn. To this end, the pixel circuit 2 includes a second transistor M2 connected between the first power supply ELVDD and the organic light emitting diode OLED, the second transistor M2, the data line Dm, and the scan line Sn. And a first capacitor M1 connected between the first transistor M1 and a storage capacitor Cst connected between the gate electrode and the first electrode of the second transistor M2.

The gate electrode of the first transistor M1 is connected to the scan line Sn, and the first electrode is connected to the data line Dm. The second electrode of the first transistor M1 is connected to one terminal of the storage capacitor Cst. Here, the first electrode is set to any one of a source electrode and a drain electrode, and the second electrode is set to an electrode different from the first electrode. For example, when the first electrode is set as the source electrode, the second electrode is set as the drain electrode. The first transistor M1 connected to the scan line Sn and the data line Dm is turned on when a scan signal is supplied from the scan line Sn to receive a data signal supplied from the data line Dm to the storage capacitor Cst. ). In this case, the storage capacitor Cst charges a voltage corresponding to the data signal.

The gate electrode of the second transistor M2 is connected to one terminal of the storage capacitor Cst, and the first electrode is connected to the other terminal of the storage capacitor Cst and the first power supply ELVDD. The second electrode of the second transistor M2 is connected to the anode electrode of the organic light emitting diode OLED. The second transistor M2 controls the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the organic light emitting diode OLED in response to the voltage value stored in the storage capacitor Cst. In this case, the organic light emitting diode OLED generates light corresponding to the amount of current supplied from the second transistor M2.

However, there is a problem in that the pixel 4 of the conventional organic light emitting display cannot display an image of uniform luminance. In detail, the threshold voltage of the second transistor M2 (driving transistor) included in each of the pixels 4 is set differently for each of the pixels 4 due to a process deviation or the like. When the threshold voltages of the driving transistors are set differently, even though the data signals corresponding to the same gray levels are supplied to the plurality of pixels 4, light having different luminance is emitted due to the difference in the threshold voltages of the driving transistors. OLED).

In order to overcome this problem, a structure in which transistors are additionally inserted in each of the pixels 4 to compensate for the threshold voltage of the driving transistor has been proposed. In practice, a structure is known in which six transistors and one capacitor are used in each of the pixels 4 to compensate for the threshold voltage of the driving transistor. However, when six transistors are included in each of the pixels 4, the size of the pixel 4 increases. In addition, there is a problem in that the probability of malfunction increases by a plurality of transistors included in the pixels 4, thereby lowering the yield.

Accordingly, an object of the present invention is to provide a pixel and an organic light emitting display device using the same, which can display an image of uniform brightness and minimize the number of transistors.

In order to achieve the above object, a pixel according to an embodiment of the present invention is an organic light emitting diode; A second transistor that is turned on when the scan signal is supplied to the scan line when the scan line is connected to the data line and the scan line; A first transistor connected between the second electrode of the second transistor and the organic light emitting diode; A third transistor connected between the gate electrode and the second electrode of the first transistor and controlled by an emission control signal supplied from an emission control line; A fourth transistor connected between a first power source and a first electrode of the first transistor, the fourth transistor being alternately turned on and off with the third transistor; A fifth transistor connected between the first transistor and the organic light emitting diode and turned off for at least a period during which the second transistor is turned on; And a storage capacitor connected between the gate electrode of the first transistor and the first power source.

Preferably, the third transistor is turned on when the emission control signal is supplied, and the fourth transistor is turned off when the emission control signal is supplied. The third transistor is formed of PMOS, and the fourth transistor is formed of NMOS. The second transistor is turned on when the scan signal is supplied, and the fifth transistor is turned off when the scan signal is supplied. The second transistor is formed of PMOS, and the fifth transistor is formed of NMOS. The storage capacitor charges a voltage corresponding to a data signal supplied from the data line via the second transistor, the first transistor, and the third transistor. The third transistor is turned on when the emission control signal is supplied, and the fourth transistor is supplied to the inverted emission control line and is turned on when the inverted emission control signal having a polarity inverted with the emission control signal is supplied. Is off. The second transistor is turned on when the scan signal is supplied, and the fifth transistor is turned off when the inverted scan signal having an inverted polarity with the scan signal is supplied when the fifth transistor is supplied to the inverted scan line. The second transistor is turned on when the scan signal is supplied to an i (i is a natural number) scan line, and the fifth transistor is supplied to an i + 1th inverted emission control line and inverted in polarity with the emission control signal. It is turned off when the inverted light emission control signal having is supplied.

An organic light emitting display device according to an embodiment of the present invention includes: a scan driver for sequentially supplying a scan signal to scan lines and sequentially supplying a light emission control signal to emission control lines; A data driver for supplying a data signal to the data lines; A pixel according to any one of claims 1 to 9 is provided at an intersection of the scan lines and the data lines.

Preferably, the scan driver supplies the scan signal supplied to the i-1 th scan line and the i th scan line and the emission control signal supplied to the i th light emission control line. The scan driver sequentially supplies the inverted scan signal to the inverted scan lines, and sequentially supplies the inverted light emission control signal to the inverted light emission control lines.

Hereinafter, preferred embodiments of the present invention may be easily implemented by those skilled in the art with reference to FIGS. 2 to 9 as follows.

2 is a diagram illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, an organic light emitting display device according to an embodiment of the present invention includes a pixel portion including pixels 140 positioned to be connected to scan lines S1 to Sn and data lines D1 to Dm. 130, the scan driver 110 for driving the scan lines S1 to Sn and the emission control lines E1 to En, the data driver 120 for driving the data lines D1 to Dm, The timing controller 150 is configured to control the scan driver 110 and the data driver 120.

The scan driver 110 receives the scan driving control signal SCS from the timing controller 150. The scan driver 110 receiving the scan driving control signal SCS sequentially supplies the scan signals to the scan lines S1 to Sn as shown in FIG. 3. In addition, the scan driver 110 receiving the scan driving control signal SCS sequentially supplies the emission control signal to the emission control lines E1 to En. Here, the light emission control signal supplied to the i (i is a natural number) th light emission control line Ei is supplied so as to overlap the scan signal supplied to the i th scan line Si and the i-1 th scan line Si-1. The light emission control signal is set to a signal having the same polarity as the scan signal. In FIG. 3, the scan signal is supplied from the first scan line S1, but the scan signal may be supplied from the zeroth scan line S0 (not shown).

The data driver 120 receives the data drive control signal DCS from the timing controller 150. The data driver 120 receiving the data driving control signal DCS generates a data signal and supplies the generated data signal to the data lines D1 to Dm in synchronization with the scan signal.

The timing controller 150 generates a data drive control signal DCS and a scan drive control signal SCS in response to external synchronization signals. The data driving control signal DCS generated by the timing controller 150 is supplied to the data driver 120, and the scan driving control signal SCS is supplied to the scan driver 110. The timing controller 150 supplies the data Data supplied from the outside to the data driver 120.

The pixel unit 130 receives the first power source ELVDD and the second power source ELVSS from the outside and supplies the same to the pixels 140. Each of the pixels 140 supplied with the first power source ELVDD and the second power source ELVSS generates light corresponding to the data signal. Here, the emission time of the pixels 140 is controlled by the emission control signal.

4 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 2. In FIG. 4, pixels connected to the nth scan line Sn and the mth data line Dm will be illustrated for convenience of description.

Referring to FIG. 4, the pixel 140 according to the first exemplary embodiment of the present invention is connected to the organic light emitting diode OLED, the data line Dm, and the scan line Sn, and is supplied to the organic light emitting diode OLED. The pixel circuit 142 for controlling the amount of current is provided.

The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 142, and the cathode electrode is connected to the second power source ELVSS. The organic light emitting diode OLED generates light having a predetermined brightness in correspondence with the amount of current supplied from the pixel circuit 142. Here, the second power supply ELVSS is set to a lower voltage value than the first power supply ELVDD.

The pixel circuit 142 controls the amount of current supplied to the organic light emitting diode OLED corresponding to the data signal supplied to the data line Dm when the scan signal is supplied to the scan line Sn. To this end, the pixel circuit 142 includes first to fifth transistors M1 to M5 and a storage capacitor Cst. The first to third transistors M1 to M3 are set as PMOS transistors, and the fourth and fifth transistors M4 and M5 are set as NMOS transistors.

The first electrode of the second transistor M2 is connected to the data line Dm, and the second electrode is connected to the first node N1. The gate electrode of the second transistor M2 is connected to the nth scan line Sn. The second transistor M2 is turned on when the scan signal is supplied to the nth scan line Sn to supply the data signal supplied to the data line Dm to the first node N1.

The first electrode of the first transistor M1 is connected to the first node N1, and the second electrode is connected to the first electrode of the fifth transistor M5. The gate electrode of the first transistor M1 is connected to the first terminal of the storage capacitor Cst. The first transistor M1 supplies a current corresponding to the voltage charged in the storage capacitor Cst to the organic light emitting diode OLED.

The first electrode of the third transistor M3 is connected to the second electrode of the first transistor M1, and the second electrode is connected to the gate electrode of the first transistor M1. The gate electrode of the third transistor M3 is connected to the nth emission control line En. The third transistor M3 is turned on when the emission control signal is supplied to the nth emission control line En to connect the first transistor M1 in the form of a diode.

The second electrode of the fourth transistor M4 is connected to the first power source ELVDD, and the first electrode is connected to the first node N1. The gate electrode of the fourth transistor M4 is connected to the emission control line En. The fourth transistor M4 is turned off when the emission control signal is supplied.

The second electrode of the fifth transistor M5 is connected to the second electrode of the first transistor M1, and the first electrode is connected to the anode electrode of the organic light emitting diode OLED. The gate electrode of the fifth transistor M5 is connected to the nth scan line Sn. The fifth transistor M5 is turned off when the scan signal is supplied to the nth scan line Sn.

The first terminal of the storage capacitor Cst is connected to the gate electrode of the first transistor M1, and the second terminal is connected to the first power source ELVDD. The storage capacitor Cst charges a voltage corresponding to the data signal.

The operation of the pixel will be described in detail with reference to the waveform diagram of FIG. 5. First, the emission control signal is supplied to the nth emission control line En during the first period T1. When the emission control signal is supplied to the nth emission control line En, the third transistor M3 is turned on and the fourth transistor M4 is turned off. The fifth transistor M5 is turned on because the scan signal is not supplied to the nth scan line Sn during the first period T1, that is, the high signal is supplied to the nth scan line Sn. Keep it.

When the third transistor M3 and the fifth transistor M5 are turned on during the first period T1, the first terminal of the storage capacitor Cst and the gate electrode of the first transistor M1 are approximately the second power source. Is initialized to the voltage of ELVSS). In fact, during the first period T1, the first terminal of the storage capacitor Cst and the gate electrode of the first transistor M1 are voltage values obtained by adding the threshold voltage of the organic light emitting diode OLED to the second power supply ELVSS. It is initialized.

The scan signal is supplied to the nth scan line Sn during the second period T2. When the scan signal is supplied to the nth scan line Sn, the second transistor M2 is turned on and the fifth transistor M5 is turned off.

When the second transistor M2 is turned on, the data signal supplied to the data line Dm is supplied to the first node N1. Here, the first transistor M1 is turned on because the gate electrode of the first transistor M1 is initialized to a voltage of approximately the second power source ELVSS during the first period T1. Then, the data signal is supplied to the first terminal of the storage capacitor Cst via the first transistor M1 and the third transistor M3. Here, since the data signal is supplied to the storage capacitor Cst through the first transistor M1 connected in the form of a diode, a voltage corresponding to the data signal and the threshold voltage of the first transistor M1 is supplied to the storage capacitor Cst. Is charged.

After the second period T2, the supply of the scan signal to the nth scan line Sn is stopped and the supply of the emission control signal to the nth emission control line En is stopped. When the supply of the scan signal to the nth scan line Sn is stopped, the second transistor M2 is turned off and the fifth transistor M5 is turned on. When supply of the emission control signal to the nth emission control line En is stopped, the third transistor M3 is turned off and the fourth transistor M4 is turned on.

When the fifth transistor M5 is turned on, the second electrode of the first transistor M1 and the organic light emitting diode OLED are electrically connected to each other. When the fourth transistor M4 is turned on, the first electrode of the first transistor M1 and the first power source ELVDD are electrically connected to each other. In this case, the first transistor M1 supplies a current corresponding to the voltage charged in the storage capacitor Cst from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED. The organic light emitting diode (OLED) generates light having a predetermined luminance in response to the amount of current supplied thereto.

As described above, the storage capacitor Cst included in each pixel 140 according to the first embodiment of the present invention is additionally charged with a voltage corresponding to the threshold voltage of the first transistor M1 as well as the data signal. Accordingly, the amount of current flowing to the organic light emitting diode OLED can be controlled regardless of the threshold voltage of the first transistor M1 included in each of the pixels 140, thereby displaying an image of uniform luminance. . In addition, since the pixel 140 according to the first embodiment of the present invention includes only five transistors M1 to M5, and no power source is added in addition to the first power source ELVDD and the second power source ELVSS, The advantage is that the structure is simplified.

Meanwhile, in the pixel 140 illustrated in FIG. 3, the fourth transistor M4 and the fifth transistor M5 are used as an NMOS type. In general, an organic light emitting display device does not use an NMOS transistor.

In detail, the NMOS transistor has a high variation in process compared to the PMOS transistor. Therefore, when the NMOS transistor is used as the driving transistor, it is difficult to display a uniform image due to variation in threshold voltage or the like. In addition, the NMOS transistor generates a high leakage current as compared with the PMOS transistor. Therefore, when the pixel is implemented by the NMOS transistor, a voltage having a desired luminance cannot be displayed due to a high leakage current.

In the pixel 140 according to the first embodiment of the present invention, since the fourth transistor M4 and the fifth transistor M5 are not used as driving transistors, the fourth transistor M4 and the fifth transistor M5 are driven regardless of the threshold voltage variation. In addition, even if a leakage current generated by the fourth transistor M4 and the fifth transistor M5 occurs in the pixel 140 according to the first embodiment of the present invention, the voltage charged in the storage capacitor Cst is not affected. This does not affect the picture quality of the displayed image.

6 is a diagram illustrating a pixel according to a second exemplary embodiment of the present invention. 6, detailed description of the same configuration as that of FIG. 4 will be omitted.

Referring to FIG. 6, in the pixel 142 according to the second embodiment of the present invention, the fourth transistor M4 and the fifth transistor M5 are formed of PMOS transistors. Here, the fourth transistor M4 is driven by the inverted emission control signal supplied to the nth inverted emission control line / En, and the fifth transistor M5 is inverted supplied to the nth inverted scan line / Sn. Driven by the scan signal.

The inverted emission control signal supplied to the nth inversion emission control line / En is supplied at the same time as the emission control signal supplied to the nth emission control line En and has an inverted polarity. The inverted scan signal supplied to the nth inverted scan line / Sn is supplied at the same time as the scan signal supplied to the nth scan line Sn and has an inverted polarity. The scan driver 110 sequentially supplies inverted emission control signals to the inverted emission control lines / E1 to / En (not shown), and sequentially supplies inverted scan signals to the inverted scan lines / S1 to / Sn. do.

An operation process of the pixel 142 according to the second embodiment of the present invention will be described in detail with reference to the waveform diagram of FIG. 7.

First, the emission control signal is supplied to the nth emission control line En and the inverted emission control signal is supplied to the nth inversion emission control line / En during the first period T1. When the emission control signal is supplied to the nth emission control line En, the third transistor M3 is turned on. When the inverted emission control signal is supplied to the nth inverted emission control line / En, the fourth transistor M4 is turned off. Here, since the low signal is supplied to the nth inversion scan line / Sn during the first period, the fifth transistor M5 maintains the turn-on state.

When the third transistor M3 and the fifth transistor M5 are turned on during the first period T1, the first terminal of the storage capacitor Cst and the gate electrode of the first transistor M1 are approximately the second power source. Is initialized to the voltage of ELVSS).

The scan signal is supplied to the nth scan line Sn during the second period T2, and the inverted scan signal is supplied to the nth inverted scan line / Sn. When the scan signal is supplied to the nth scan line Sn, the second transistor M2 is turned on. When the inverted scan signal is supplied to the nth inverted scan line / Sn, the fifth transistor M5 is turned off.

When the second transistor M2 is turned on, the data signal supplied to the data line Dm is supplied to the first node N1. Here, the first transistor M1 is turned on because the gate electrode of the first transistor M1 is initialized to a voltage of approximately the second power source ELVSS during the first period T1. Then, the data signal is supplied to the first terminal of the storage capacitor Cst via the first transistor M1 and the third transistor M3. Here, since the data signal is supplied to the storage capacitor Cst through the first transistor M1 connected in the form of a diode, the storage capacitor Cst corresponds to the data signal and the threshold voltage of the first transistor M1. The voltage is charged.

After the second period T2, the supply of the scan signal, the inverted scan signal, the light emission control signal, and the inverted light emission control signal is stopped. When the supply of the scan signal is stopped, the second transistor M2 is turned off. When the supply of the inverted scan signal is stopped, the fifth transistor M5 is turned on. When supply of the emission control signal is stopped, the third transistor M3 is turned off. When the supply of the inverted emission control signal is stopped, the fourth transistor M4 is turned on.

When the fifth transistor M5 is turned on, the second electrode of the first transistor M1 and the organic light emitting diode OLED are electrically connected to each other. When the fourth transistor M4 is turned on, the first electrode of the first transistor M1 and the first power source ELVDD are electrically connected to each other. In this case, the first transistor M1 supplies a current corresponding to the voltage charged in the storage capacitor Cst from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED. The organic light emitting diode (OLED) generates light having a predetermined brightness in response to the amount of current supplied thereto.

The storage capacitor Cst included in each pixel 140 according to the second embodiment of the present invention is additionally charged with a voltage corresponding to the threshold voltage of the first transistor M1 as well as the data signal. Accordingly, the amount of current flowing to the organic light emitting diode OLED can be controlled regardless of the threshold voltage of the first transistor M1 included in each of the pixels 140, thereby displaying an image of uniform luminance. . In addition, since the pixel 140 according to the second embodiment of the present invention includes only five transistors M1 to M5, and no power source is added in addition to the first power source ELVDD and the second power source ELVSS, The advantage is that the structure is simplified.

8 is a diagram illustrating a pixel according to a third exemplary embodiment of the present invention. When describing FIG. 8, detailed description of the same configuration as that of FIG. 6 will be omitted.

Referring to FIG. 8, in the pixel 142 according to the third exemplary embodiment of the present invention, the fifth transistor M5 is supplied by an inverted emission control signal supplied to the n + 1 inverted emission control line / En + 1. Driven. As described above, when the fifth transistor M5 is driven by the n + 1th inversion light emission control line / En + 1, the inverted scan line / Sn can be removed as compared with FIG.

The operation of the pixel 142 according to the third embodiment of the present invention will be described in detail with reference to the waveform diagram of FIG. 9.

First, the emission control signal is supplied to the nth emission control line En and the inverted emission control signal is supplied to the nth inversion emission control line / En during the first period T1. When the emission control signal is supplied to the nth emission control line En, the third transistor M3 is turned on. When the inverted emission control signal is supplied to the nth inverted emission control line / En, the fourth transistor M4 is turned off. Here, the fifth transistor M5 maintains the turn-on state because the low signal is supplied to the n + 1 inverted emission control line / En + 1 during the first period T1.

When the third transistor M3 and the fifth transistor M5 are turned on during the first period T1, the first terminal of the storage capacitor Cst and the gate electrode of the first transistor M1 are approximately the second power source. Is initialized to the voltage of ELVSS).

The scan signal is supplied to the nth scan line Sn during the second period T2, and the inverted emission control signal is supplied to the n + 1th inverted emission control line / En + 1. When the scan signal is supplied to the nth scan line Sn, the second transistor M2 is turned on. When the inverted emission control signal is supplied to the n + 1th inverted emission control line / En + 1, the fifth transistor M5 is turned off.

When the second transistor M2 is turned on, the data signal supplied to the data line Dm is supplied to the first node N1. Here, the first transistor M1 is turned on because the gate electrode of the first transistor M1 is initialized to a voltage of approximately the second power source ELVSS during the first period T1. Then, the data signal is supplied to the first terminal of the storage capacitor Cst via the first transistor M1 and the third transistor M3. Here, since the data signal is supplied to the storage capacitor Cst through the first transistor M1 connected in the form of a diode, a voltage corresponding to the data signal and the threshold voltage of the first transistor M1 is supplied to the storage capacitor Cst. Is charged.

After the second period T2, the supply of the scan signal, the light emission control signal, and the inverted light emission control signal is stopped. When the supply of the scan signal is stopped, the second transistor M2 is turned off. When supply of the emission control signal is stopped, the third transistor M3 is turned off. When the supply of the inverted light emission control signal is stopped, the fourth transistor M4 and the fifth transistor M5 are turned on.

When the fifth transistor M5 is turned on, the second electrode of the first transistor M1 and the organic light emitting diode OLED are electrically connected to each other. When the fourth transistor M4 is turned on, the first electrode of the first transistor M1 and the first power source ELVDD are electrically connected to each other. In this case, the first transistor M1 supplies a current corresponding to the voltage charged in the storage capacitor Cst from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED. The organic light emitting diode (OLED) generates light having a predetermined brightness in response to the amount of current supplied thereto.

The storage capacitor Cst included in each pixel 140 according to the third exemplary embodiment of the present invention is additionally charged with a voltage corresponding to the threshold voltage of the first transistor M1 as well as the data signal. Accordingly, the amount of current flowing to the organic light emitting diode OLED can be controlled regardless of the threshold voltage of the first transistor M1 included in each of the pixels 140, thereby displaying an image of uniform luminance. . In addition, since the pixel 140 according to the third embodiment of the present invention includes only five transistors M1 to M5, and there is no power source other than the first power supply ELVDD and the second power supply ELVSS, The advantage is that the structure is simplified.

The above detailed description and drawings are merely exemplary of the present invention, but are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the meaning or claims. Accordingly, those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical protection scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

As described above, according to the pixel and the organic light emitting display device using the same according to an embodiment of the present invention, the voltage charged in the storage capacitor is controlled to compensate for the threshold voltage of the driving transistor (first transistor) included in each pixel. Therefore, an image of uniform luminance can be displayed. In addition, the pixel of the present invention uses five transistors and one capacitor, and since there is no power source other than the first power source and the second power source, the pixel structure is simplified and the probability of malfunction of the transistors can be reduced.

Claims (12)

An organic light emitting diode; A second transistor that is turned on when the scan signal is supplied to the scan line when the scan line is connected to the data line and the scan line; A first transistor connected between the second electrode of the second transistor and the organic light emitting diode; A third transistor connected between the gate electrode and the second electrode of the first transistor and controlled by an emission control signal supplied from an emission control line; A fourth transistor connected between a first power source and a first electrode of the first transistor, the fourth transistor being alternately turned on and off with the third transistor; A fifth transistor connected between the first transistor and the organic light emitting diode and turned off for at least a period during which the second transistor is turned on; And a storage capacitor connected between the gate electrode of the first transistor and the first power source. The method of claim 1, And the third transistor is turned on when the emission control signal is supplied, and the fourth transistor is turned off when the emission control signal is supplied. The method of claim 2, And the third transistor is formed of PMOS, and the fourth transistor is formed of NMOS. The method of claim 1, And the second transistor is turned on when the scan signal is supplied, and the fifth transistor is turned off when the scan signal is supplied. The method of claim 4, wherein And the second transistor is formed of PMOS, and the fifth transistor is formed of NMOS. The method of claim 1, And the storage capacitor charges a voltage corresponding to a data signal supplied from the data line via the second transistor, the first transistor, and the third transistor. The method of claim 1, The third transistor is turned on when the emission control signal is supplied, and the fourth transistor is supplied to the inverted emission control line and is turned on when the inverted emission control signal having a polarity inverted with the emission control signal is supplied. Pixels which are turned off. The method of claim 1, The second transistor is turned on when the scan signal is supplied, and the fifth transistor is turned off when the inverted scan signal having an inverted polarity with the scan signal is supplied when the fifth transistor is supplied to the inverted scan line. Pixel to say. The method of claim 1, The second transistor is turned on when the scan signal is supplied to an i (i is a natural number) scan line, and the fifth transistor is supplied to an i + 1th inverted emission control line and inverted in polarity with the emission control signal. And turn off when the inverted light emission control signal having the? A scan driver for sequentially supplying scan signals to scan lines and sequentially supplying light emission control signals to light emission control lines; A data driver for supplying a data signal to the data lines; An organic light emitting display device comprising: the pixel according to any one of claims 1 to 9 at an intersection of the scan lines and the data lines. The method of claim 10, And the scan driver supplies the scan signal supplied to the i-1 th scan line and the i th scan line and the emission control signal supplied to the i th light emission control line so as to overlap each other. The method of claim 11, And the scan driver sequentially supplies the inverted scan signal to the inverted scan lines, and sequentially supplies the inverted light emission control signal to the inverted light emission control lines.

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