KR100684714B1 - Light emitting display device and driving method thereof - Google Patents

Abstract

In an organic light emitting diode display, a first electrode of a first capacitor is connected to a gate of a driving transistor, and a second capacitor is connected between a second electrode of a first capacitor and a power supply voltage. First, a compensation voltage is applied to the second electrode of the first capacitor for a predetermined period of time. While applying the compensation voltage to the second electrode of the first capacitor, the driving transistor is connected in the form of a diode to store the threshold voltage of the driving transistor in the first capacitor. Next, after the data voltage is applied to the second electrode of the first capacitor, the driving transistor is driven by the voltages stored in the first and second capacitors. As described above, the problem of variation in the threshold voltage of the driving transistor and the problem of voltage drop in the power supply voltage can be solved, and the charging time of the compensation voltage can be sufficiently secured.

Light emitting display, OLED, luminance difference, voltage drop, threshold voltage

Description

LIGHT EMITTING DISPLAY AND DRIVING METHOD THEREOF

1 is a conventional pixel circuit for driving an organic light emitting element.

2 is a diagram illustrating a connection state of a voltage supply line in a display panel of a general organic light emitting diode display.

3 is a schematic diagram of a light emitting display device according to an embodiment of the present invention.

4 is a circuit diagram of a pixel according to a first embodiment of the present invention.

5 is a driving timing diagram for driving the pixel of FIG. 4.

FIG. 6 is a graph illustrating deviations generated between threshold voltages compensated according to a charging speed of a compensation voltage.

7 is a circuit diagram of a pixel according to a second embodiment of the present invention.

8 to 10 are driving timing diagrams for driving the pixels of FIG. 7, respectively.

11 to 13 are circuit diagrams of pixels according to third to fifth embodiments of the present invention, respectively.

The present invention relates to a light emitting display device, and more particularly, to an organic light emitting display device and a driving method thereof.

In general, an organic light emitting diode display is a display device that electrically excites a fluorescent organic material to emit light, and may display an image with a plurality of organic light emitting cells. The organic light emitting cell has a structure of an anode, an organic thin film, and a cathode layer. The organic thin film has a multilayer structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) to improve the emission efficiency by improving the balance between electrons and holes. It may also include a separate electron injecting layer (EIL) and a hole injecting layer (HIL).

The active driving method of driving the organic light emitting cell is the driving method of connecting the thin film transistor and the capacitor to the pixel electrode to maintain the voltage by the capacitor capacitance. In this case, the active driving method is divided into a voltage programming method and a current programming method according to the type of signal applied to maintain the voltage on the capacitor.

FIG. 1 is a conventional pixel circuit for driving an organic light emitting device, and representatively illustrates a pixel circuit connected to a data line Dm and a scan line Sn among a plurality of pixel circuits.

As shown in FIG. 1, the transistor M1 is connected to the organic light emitting diode OLED to supply a current for emitting light. The amount of current in the transistor M1 is controlled by the data voltage applied through the switching transistor M2. At this time, a capacitor Cst for maintaining the applied voltage for a predetermined period is connected between the source and the gate of the transistor M2. The gate of the transistor M2 is connected to the scan line Sn and the source is connected to the data line Dm.

At this time, the current flowing through the OLED is represented by Equation 1 below.

Where I _OLED is the current flowing through the OLED, Vgs is the voltage between the gate and the source of the transistor M1, Vth is the threshold voltage of the transistor M1, Vdata is the data voltage, and β is a constant value. .

In general, the power supply line for supplying the power supply voltage VDD to the pixel circuit is formed as a horizontal line or a vertical line. For example, when the power supply line is formed in a horizontal line as shown in FIG. 2 and power is supplied from the left side, a voltage difference between the left and right sides of the power supply line occurs due to the voltage drop on each branched power supply line. In addition, when the power supply line is formed as a vertical line, a voltage difference occurs between the upper side and the lower side of the power supply line.

Therefore, in FIG. 2, since the power supply voltage VDD applied to the right pixel of the power supply line is lower than the power supply voltage VDD applied to the left pixel, the gate-source voltage Vgs of the driving transistor located in the right pixel is left. The voltage between the gate and source voltages Vgs of the driving transistor positioned in the pixel is lower. Therefore, as shown in Equation 1, even when the same data is applied to the pixel circuits on the left and right sides of the power supply line, the amount of current flowing through the driving transistor is different, resulting in a luminance difference.

On the other hand, in the conventional pixel circuit, in addition to the luminance difference caused by the voltage drop of the power supply line, there is also the luminance difference due to the deviation of the threshold voltage Vth of the transistor caused by the nonuniformity of the manufacturing process. That is, in Equation 1, since the amount of current supplied to the organic light emitting diode OLED depends on the threshold voltage of the transistor, the light emission luminance varies according to the variation of the threshold voltage.

An object of the present invention is to provide a light emitting display device capable of expressing uniform luminance by compensating for variations in threshold voltages of driving transistors included in a pixel circuit.

Another object of the present invention is to provide a light emitting display device capable of expressing uniform luminance by compensating for a difference in voltage drop between pixels generated in a driving voltage line.

According to an aspect of the present invention, there is provided a light emitting display device including a plurality of data lines for transmitting a data voltage, a plurality of scan lines for transmitting a selection signal, and a plurality of pixel circuits. The pixel circuit of the present invention includes a transistor, a light emitting element, a first capacitor, and first and second switches.

In the transistor, a first electrode is electrically connected to a first power supply for supplying a first voltage, and outputs a current corresponding to a voltage applied between the first electrode and the second electrode to the third electrode. The light emitting device emits light in response to the current output to the third electrode of the transistor, and the first capacitor stores a voltage corresponding to the threshold voltage of the transistor during the first period. The first switch is connected between a first electrode of the first capacitor and a second power supply for supplying a second voltage, and is turned on for a second period longer than the first period. The second switch applies a data voltage from the data line to the first electrode of the first capacitor in response to the selection signal from the scan line. The voltage between the first electrode and the second electrode of the transistor depends on the voltage of the first capacitor.

A pixel circuit according to another feature of the present invention includes a transistor, a light emitting element, first to third switches, and first and second capacitors. The transistor outputs a current corresponding to the voltage applied between the first and second electrodes to the third electrode, and the light emitting element is electrically connected to the third electrode of the transistor and emits light corresponding to the applied current. The first capacitor has a first electrode connected to the first electrode of the transistor, and the second capacitor is connected between a first power supply and a second electrode of the first capacitor. The first switch connects the transistor in the form of a diode in response to a first control signal, and the second switch connects the second electrode and the second power supply of the first capacitor in response to a second control signal. The third switch transfers the data voltage to the first capacitor in response to the selection signal. The first and second control signals are applied to the pixel circuit before the selection signal is applied, and the period during which the second control signal is applied to the pixel circuit is longer than the period during which the selection signal is applied.

According to another feature of the invention, a transistor for outputting a current corresponding to the voltage applied between the first and second electrodes to the third electrode, the light emitting device for emitting light corresponding to the current output from the third electrode of the transistor And a pixel circuit including a first capacitor connected to the first electrode of the transistor, and a second capacitor connected between a first power supply and a second electrode of the first capacitor. A method is provided. According to the driving method of the present invention, a second voltage is applied to the second electrode of the first capacitor during the first period. The first capacitor is charged with a voltage corresponding to the threshold voltage of the transistor for a second period shorter than the first period. The voltage corresponding to the data voltage is charged in the first and second capacitors during the third period.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification. When a part is connected to another part, this includes not only a direct connection but also an indirect connection between other elements in between.

In the exemplary embodiment of the present invention, an organic light emitting display device using light emission of an organic material is described as an example.

3 is a schematic conceptual diagram of an organic light emitting diode display according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the light emitting display device according to the exemplary embodiment of the present invention includes a display panel 100, a data signal driver 200, a selection signal driver 300, and a light emitting signal driver 400.

The display panel 100 includes a plurality of data lines D1 -Dm extending in a column direction, a plurality of selection scan lines S1 -Sn, a light emitting scan line E1-En, and a plurality of pixel circuits 110 extending in a row direction. ). The data lines D1 -Dm transmit a data signal (hereinafter, referred to as a "data voltage") in the form of a voltage representing an image signal to the pixel circuit 110. The selection scan lines S1 -Sn transfer the selection signal to the pixel circuit 110, and the emission scan lines E1 -En transfer the emission signal to the pixel circuit 110. The pixel circuit 110 is formed in a pixel area defined by two neighboring data lines D1 -Dm and two neighboring scan lines S1 -Sn.

The data signal driver 200 applies a data voltage to the data lines D1 -Dm. The selection signal driver 300 sequentially applies the selection signals to the selection scan lines S1 -Sn, and the emission signal driver 400 sequentially applies the emission signals to the emission scan lines E1 -En.

The data signal driver 200, the selection signal driver 300, and / or the light emission signal driver 400 may be electrically connected to the display panel 100 or may be attached to the display panel 100 and electrically connected to the tape carrier. The package may be mounted in the form of a chip in a tape carrier package (TCP). Alternatively, the display panel 100 may be mounted in a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 100 in the form of a chip. Alternatively, the data signal driver 200, the selection signal driver 300, and / or the light emission signal driver 400 may be directly mounted on the substrate of the display panel 100, or may include scan lines, data lines, and thin film transistors on the substrate. It may be replaced or directly mounted with a driving circuit formed of the same layers.

4 is an equivalent circuit diagram of a pixel circuit according to a first embodiment of the present invention.

In FIG. 4, only the pixel circuit connected to the m-th data line Dm and the n-th scan line Sn and En is illustrated for convenience of description. On the other hand, when the terms relating to the selection scan line are defined, the scanning line to which the current selection signal is to be transmitted is referred to as the "current selection scanning line", and the scanning line to which the selection signal is transmitted before the current selection signal is transmitted is referred to as the "previous selection scanning line".

As shown in FIG. 4, the pixel circuit 110 according to the first embodiment of the present invention includes transistors M1-M5, capacitors Cst and Cvth, and an organic light emitting diode OLED. In FIG. 4, transistors M1-M5 are illustrated as NMOS transistors, and transistors M2-M5 are turned on by a low level select signal and a light emission signal.

The transistor M1 is a driving transistor for driving the organic light emitting diode OLED. The transistor M1 is connected between the power supply for supplying the power supply voltage VDD and the organic light emitting diode OLED. The transistor M5 is applied by a voltage applied to the gate. The current flowing through the organic light emitting diode OLED is controlled through the. The transistor M2 connects the transistor M1 in the form of a diode in response to a low level selection signal from the previous selection scan line Sn-1.

The first electrode A of the capacitor Cvth is connected to the gate of the transistor M1, and the capacitor Cst is connected between the second electrode B of the capacitor Cvth and the power supply for supplying the power voltage VDD. It is connected. In addition, the transistor M4 is connected between the second electrode B of the capacitor Cvth and the power supply for supplying the compensation voltage Vsus, so as to respond to the low level selection signal from the previous selection scan line Sn-1. The compensation voltage Vsus is applied to the other electrode B of the capacitor Cvth.

The transistor M3 transfers the data voltage from the data line Dm to the second electrode B of the capacitor Cvth in response to the low level selection signal from the current selection scan line Sn.

The transistor M5 is connected between the drain of the transistor M1 and the anode of the organic light emitting element OLED, and responds to the high level light emission signal from the light emission scan line En and the drain of the transistor M1 and the organic light emitting element. Block (OLED).

The OLED emits light in response to an input current. According to the first embodiment of the present invention, the power supply voltage VSS connected to the cathode of the OLED is a voltage having a lower level than the power supply voltage VDD, and a ground voltage, a negative voltage, and the like may be used. .

Hereinafter, an operation of the pixel circuit according to the first embodiment of the present invention will be described with reference to FIG. 5.

In the T1 period, when the low level select signal is applied to the immediately preceding scan line Sn-1, the transistor M1 is connected in the form of a diode. In addition, since the transistor M5 is turned off by the high-level emission signal applied to the emission scan line En, when the gate-source voltage of the transistor M1 becomes the threshold voltage Vth of the transistor M1. Changes up to Therefore, a voltage corresponding to the sum of the voltage VDD and the threshold voltage Vth of the transistor M1 is applied to the gate of the transistor M1, that is, the first electrode A of the capacitor Cvth.

In addition, since the transistor M4 is turned on, the compensation voltage Vsus is applied to the second electrode B of the capacitor Cvth, and the capacitor _Cvth is charged with the voltage V _Cvth as shown in Equation 2 below.

In the T2 period, the selection signal of the immediately preceding scan line Sn-1 is at a high level so that the transistors M2 and M4 are turned off. A low level selection signal is applied to the current scan line Sn to turn on the transistor M3, and the data voltage Vdata is applied to the second electrode B of the capacitor Cvth. Since the capacitor Cvth is charged with the voltage as shown in Equation 2, the voltage between the gate and the source of the transistor M1 is as shown in Equation 3. In the T2 period, the transistor M5 is turned off.

Therefore, the current flowing through the OLED is represented by Equation 4.

As can be seen from Equation 4, the current flowing through the organic light emitting diode OLED is not affected by the power supply voltage VDD, and the luminance deviation due to the voltage drop in the power supply voltage VDD supply line can be compensated for.

In the T1 period in which the compensation voltage Vsus is applied, since a current path is not formed by the power supply for supplying the compensation voltage Vsus, a problem of voltage drop due to current flow does not occur. Therefore, substantially the same compensation voltage Vsus is applied to all the pixel circuits, and a current corresponding to the data voltage may flow through the OLED.

However, when the compensation voltage Vsus is charged to the capacitor Cvth during the T1 period, the power supply line to which the pixel supplies the compensation voltage Vsus by the parasitic capacitance component present in the power supply line supplying the compensation voltage Vsus. The rate at which the compensation voltage Vsus is charged to the second electrode B of the capacitor Cvth may vary depending on the position connected to the second electrode B.

FIG. 6 illustrates a rate at which the compensation voltage Vsus is charged to two pixels formed at different positions of the display panel, and a voltage charged at the capacitor Cvth.

In FIG. 6, (a) and (b) are graphs showing the rate at which the compensation voltage is charged to the pixels connected to the same compensation voltage (Vsus) supply line, and (a) is close to the power supply for supplying the compensation voltage (Vsus). The case of a pixel located at a point is shown, and (b) shows the case of a pixel located at a distant point. In addition, (c) shows a voltage charged in the capacitor (Cvth) of the pixel formed at a point close to the power supply, (d) shows a voltage charged in the capacitor (Cvth) of the pixel formed at a point far from the power source. It is.

As can be seen in FIG. 6, the speed at which the compensation voltage Vsus is charged to the second electrode B of the capacitor Cvth varies according to the position at which the pixel is formed, and the pixel farther from the power source, the compensation voltage Vsus. This charging rate is slowed down. The voltage charged in the capacitor Cvth varies as shown in the graphs (c) and (d) according to the charging speed of the compensation voltage Vsus.

Therefore, during the T1 period, the capacitor Cvth is charged with a voltage different from the threshold voltage of the driving transistor M1, so that variations in the threshold voltage of the driving transistor M1 are not compensated for accurately, which makes it difficult to express uniform luminance.

In the second embodiment of the present invention, a sufficient time for the compensation voltage Vsus to be charged to the second electrode B of the capacitor Cvth ensures that the voltage charged to the capacitor Cvth is charged with the compensation voltage Vsus. Don't be affected by speed.

Hereinafter, a pixel circuit according to a second exemplary embodiment of the present invention will be described with reference to FIGS. 7 and 8.

7 is a circuit diagram illustrating a pixel according to a second exemplary embodiment of the present invention, and FIGS. 8 to 10 are driving timing diagrams for driving the pixel of FIG. 7, respectively.

As shown in FIG. 7, the pixel circuit according to the second embodiment of the present invention controls the on / off of the transistor M4 by using the control signal line EBn-1 formed separately from the selection scan line. The difference from the pixel circuit according to the first embodiment of FIG.

Referring to FIG. 8, when the low level control signal is applied to the control signal line EBn-1 in the T1 'period, the transistor M4 is turned on to apply the compensation voltage Vsus to the other electrode B of the capacitor Cvth. do. As illustrated in FIG. 8, the period T1 ′ includes the period T1 and the period immediately before the period T1 of FIG. 5.

In other words, the transistor M1 is connected in the form of a diode so that the compensation voltage is longer than the low level period of the previous selection signal T1 ′, which is the period T1 during which the threshold voltage of the transistor M1 is charged to the capacitor Cvth. Vsus is applied to the second electrode B of the capacitor Cvth. Therefore, a time sufficient to charge the compensation voltage Vsus to the capacitor Cvth can be secured as compared with the first embodiment.

Since the control signal of the control signal line EBn-1 needs to be at a low level for a period longer than the T1 period, an inverted signal of the light emission signal applied to the previous light emission scan line En-1 may be used as shown in FIG. 9. have. As described above, when the inversion signal of the light emission signal applied to the previous light emission scan line En-1 is used, the control for controlling the on / off of the transistor M4 without adding a separate driver for controlling the transistor M4. You can generate a signal.

As described above, according to the second embodiment of the present invention, the capacitor Cvth may be charged to the compensation voltage Vsus before the threshold voltage Vth of the transistor M1 is stored in the capacitor Cvth. It is possible to prevent the variation of the threshold voltage Vth stored in the capacitor Cvth by the charging speed of the compensation voltage Vsus.

In particular, in the high resolution display device, the pixel pitch becomes very small. In this case, when the power line for transmitting the compensation voltage Vsus is formed in the row direction, the width of the power line for delivering the compensation voltage Vsus becomes small. Delays caused by parasitic capacitance components are inevitable. Therefore, in the second embodiment of the present invention, the compensation voltage Vsus is applied to the second electrode B of the capacitor Cvth by using the light emission signal having a long pulse width, whereby the compensation voltage Vsus becomes the capacitor Cvth. Make sure it is fully charged.

In addition, since the number of transistors controlled by the selection scan line is reduced, the load of the selection signal driver 300 is reduced. Therefore, the size of the buffer formed in the selection signal driver 300 may be reduced, and the internal circuit may operate smoothly.

8 and 9 illustrate that the selection signal is applied to the current selection scan line Sn immediately after the selection signal is applied to the previous selection scan line Sn- 1, but according to the embodiment, the previous selection is performed as shown in FIG. 10. A blank period can be set for a predetermined period T4 between the signal and the current selection signal.

When the light emitting display device is actually implemented, a problem may occur in which a selection signal of the current selection scan line Sn and a selection signal of the previous selection scan line Sn-1 overlap with each other due to a parasitic component present in the selection scan line. In this case, the switching transistors M2 and M3 of the pixel circuit are turned on, thereby causing a malfunction of the pixel circuit.

Accordingly, as shown in FIG. 10, the parasitic component of the selection scan line is delayed by delaying the selection signal applied to the current selection scan line Sn during the blank period T4, which may occur due to the delay of the previous selection scan line Sn-1. Can solve the problem.

In addition, in the second embodiment of the present invention, a separate control signal line EBn-1 is used to control the transistor M4. Alternatively, another signal line used in the pixel circuit of the first embodiment may be used as the control signal line EBn-1. Can also be used as). This embodiment will be described in detail with reference to FIG.

11 is a circuit diagram illustrating a pixel according to a third exemplary embodiment of the present invention.

Referring to FIG. 11, in the pixel according to the third exemplary embodiment, the transistor M4 ′ is formed of a transistor having an N-type channel, unlike the transistor M4, and a light emitting scan line immediately before the gate of the transistor M4 ′. (En-1) is connected. In this case, as illustrated in FIG. 9, the transistor M4 ′ is turned on during the period T1 ′ in which the light emission signal of the previous light emission scan line En-1 is at a high level to sufficiently secure the charge voltage Vsus charging time. can do.

In the embodiment of the present invention, the transistor M2 is controlled by the selection signal of the previous scan line Sn-1, but the transistor M4 can be controlled by the signal controlling the transistor M4. It demonstrates with reference to FIG.

12 is a circuit diagram illustrating a pixel according to a fourth exemplary embodiment of the present invention. 12 may be driven by the driving waveforms of FIGS. 8 and 9.

As shown in FIG. 12, the pixel circuit of FIG. 7 controls the transistor M2 using the control signal line EBn-1 for controlling the transistor M4. It differs from the circuit.

In the non-T1 period of the T1 'period, the transistor M1 is connected in a diode form by the turn-on of the transistor M2, but the transistor M5 is turned on, so the capacitor Cvth has a threshold voltage Vth of the transistor M1. ) Does not charge. As in the second embodiment, the Vsus voltage is applied to the second electrode B of the capacitor Cvth.

Next, since the threshold voltage Vth of the transistor M1 is charged to the capacitor Cvth by turning off the transistor M5 in the T1 period, the same effect as in the second embodiment is obtained.

As described in the third embodiment, the immediately preceding light emission scan line En-1 may be used in place of the control signal line EBn-1 in the pixel circuit of FIG. 12, and this embodiment is illustrated in FIG. 13.

Referring to FIG. 13, in the pixel circuit according to the fifth embodiment of the present invention, transistors M2 ′ and M4 ′ are formed of N type transistors, unlike transistors M2 and M4, and transistors M2 ′ and M4 ′. 12 has the same structure as the pixel circuit of FIG. 12 except that the previous light emission scan line En-1 is connected to the gate of FIG.

In the above, the light emitting display device according to the embodiment of the present invention has been described. The above-described embodiment is an embodiment to which the concept of the present invention is applied, and the scope of the present invention is not limited to the above embodiment, and various modifications may be made by using the concept of the present invention as it is.

According to the present invention, the luminance uniformity of the light emitting display device can be improved by compensating for the deviation between the threshold voltage and the power supply voltage of the driving transistor included in the pixel circuit.

In addition, by sufficiently securing the compensation voltage charging period in the pixel circuit, it is possible to prevent a deviation between the threshold voltages compensated according to the charging speed of the compensation voltage.

Furthermore, the load of the selection signal driver may be reduced to reduce the size of the buffer present in the selection signal driver, thereby facilitating the operation of the internal circuit.

Claims (20)

A light emitting display device comprising a plurality of data lines for transmitting a data voltage, a plurality of scanning lines for transmitting a selection signal, and a plurality of pixel circuits. The pixel circuit, A transistor electrically connected to a first power supply for supplying a first voltage and outputting a current corresponding to a voltage applied between the first electrode and the second electrode to a third electrode; A light emitting device that emits light corresponding to a current output to the third electrode of the transistor; A first capacitor that stores a voltage corresponding to the threshold voltage of the transistor for a first period of time, A first switch connected between a first electrode of the first capacitor and a second power supply for supplying a second voltage, the first switch being turned on for a second period longer than the first period, and A second switch applying a data voltage from the data line to the first electrode of the first capacitor in response to the selection signal from the scan line, The voltage between the first electrode and the second electrode of the transistor is dependent on the voltage of the first capacitor. The method of claim 1, The second period includes the first period, and wherein the start of the second period precedes the start of the first period in time. The method according to claim 1 or 2, And a second capacitor connected between the first power supply and the first electrode of the first capacitor, The second electrode of the first capacitor is connected to the second electrode of the transistor, and the voltage between the first electrode and the second electrode of the transistor is determined by the sum of the voltages of the first capacitor and the second capacitor. Light emitting display device. The method of claim 3, A third switch connecting the transistor in the form of a diode in response to a first control signal, and A fourth switch transferring a current from a third electrode of the transistor to the light emitting element in response to a second control signal, The first switch is turned on in response to a third control signal. The method of claim 4, wherein The first period is a period during which the third switch is turned on and the fourth switch is turned off. The method of claim 5, The start of the third period is later than the end of the first period, and the fourth switch is turned on after the third period. The method of claim 6, And the first control signal is a selection signal applied immediately before the selection signal is applied to the second switch of the pixel circuit. The method of claim 7, wherein The first switch and the fourth switch are transistors of opposite conductivity types, And the third control signal is a second control signal applied immediately before the second control signal is applied to the pixel circuit applied to the fourth switch. The method of claim 7, wherein The first switch and the fourth switch are transistors having the same conductivity type, And the third control signal is a second control signal applied immediately before the second control signal is applied to the pixel circuit applied to the fourth switch. The method of claim 7, wherein The first and third switches are transistors of a first conductivity type, the fourth switch is a transistor of a second conductivity type opposite to the first conductivity type, And the first and third control signal signals are second control signals applied immediately before the second control signal is applied to the pixel circuit applied to the fourth switch. The method of claim 7, wherein The first, third and fourth switches are transistors having the same conductivity type, And the first and third control signal signals are inverted signals of a second control signal applied immediately before the second control signal is applied to the pixel circuit applied to the fourth switch. A light emitting display device comprising a plurality of data lines for transmitting a data signal, a plurality of scanning lines for transmitting a selection signal, and a plurality of pixel circuits. The pixel circuit, A transistor for outputting a current corresponding to a voltage applied between the first and second electrodes to the third electrode, A light emitting device electrically connected to the third electrode of the transistor and emitting light in response to an applied current; A first switch for connecting the transistor in the form of a diode in response to a first control signal, A first capacitor having a first electrode connected to the first electrode of the transistor, A second capacitor connected between a first power supply and a second electrode of the first capacitor, A second switch connecting the second electrode and the second power supply of the first capacitor in response to a second control signal; and A third switch transferring the data voltage to the first capacitor in response to the selection signal; The first and second control signals are applied to the pixel circuit before the selection signal is applied, and the light emitting display device has a longer period than the period during which the selection signal is applied to the pixel circuit. . The method of claim 12, The pixel circuit further comprises a fourth switch electrically blocking the third electrode and the light emitting element of the transistor in response to a third control signal. The method of claim 13, And the first control signal is a selection signal immediately before a selection signal applied to the third switch of the pixel circuit. The method according to claim 13 or 14, And the second control signal is generated from a third control signal applied immediately before the third control signal is applied to the pixel circuit. The method of claim 13, And the first and second control signals are generated from a third control signal applied immediately before the third control signal is applied to the pixel circuit. The method according to claim 1 or 12, wherein The light emitting device is a light emitting device using light emission of an organic material. A transistor for outputting a current corresponding to a voltage applied between the first and second electrodes to a third electrode, a light emitting device that emits light corresponding to the current output from the third electrode of the transistor, and a first electrode of the transistor A method of driving a light emitting display device having a pixel circuit including a first capacitor connected to a first electrode, and a second capacitor connected between a first power supply and a second electrode of the first capacitor, Applying a second voltage to a second electrode of the first capacitor during a first period of time, Charging the first capacitor with a voltage corresponding to the threshold voltage of the transistor for a second period shorter than the first period, and And charging a voltage corresponding to the data voltage to the first and second capacitors during a third period of time. The method of claim 18, And the first period begins before the second period and is maintained for the second period. The method of claim 18 or 19, And the first period and the second period begin before the third period.

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