KR100595108B1 - Pixel and light emitting display device and driving method thereof - Google Patents

Abstract

The present invention relates to a pixel for displaying an image of uniform brightness and reducing the load of a scan driver.

According to an exemplary embodiment of the present invention, a pixel includes a first transistor connected to a diode such that a forward bias is applied when an initialization voltage is supplied from a data line, and a second transistor outputting a current corresponding to the data signal supplied to the data line. A pixel circuit supplied to the gate terminal of the second transistor via the first transistor; And a light emitting device that emits light corresponding to the current output from the pixel circuit.

With this arrangement, in the present invention, the initialization voltage and the data signal are continuously supplied to the data line, and the pixels can be initialized so that the pixels can be normally obtained using the initialization voltage. As such, when the pixel is initialized by the initialization voltage supplied from the data line, the load of the scan driver may be reduced, thereby realizing a light emitting display device having a large area and a high resolution.

Description

Pixel and Light Emitting Display and Driving Method Thereof}             

1 is a circuit diagram showing a conventional pixel.

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

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

4 is a waveform diagram illustrating a method of driving a light emitting display device of the present invention.

5 is a circuit diagram illustrating a pixel according to a second exemplary embodiment of the present invention.

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

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

8 is a circuit diagram illustrating a pixel according to a fifth exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10,110: scan driver 20,120: data driver

30,130: image display unit 40,140,200: pixel

50,150: timing controller 142,202: pixel circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel, a light emitting display, and a driving method thereof. More particularly, the present invention relates to a pixel, a light emitting display, and a driving method thereof capable of displaying an image of uniform brightness and reducing the load of a scan driver.

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, a light emitting display, and the like.

Among the flat panel display devices, the light emitting display device is a self-light emitting device that generates light by recombination of electrons and holes. Such a light emitting display device has an advantage in that it has a fast response speed and is driven with low power consumption. In general, a light emitting display device uses a thin film transistor (TFT), which is formed for each pixel, to supply light corresponding to a data signal to the light emitting device to emit light from the light emitting device.

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

Referring to FIG. 1, the pixel 4 of the conventional light emitting display generates light corresponding to the data signal supplied to the data line D when a scan signal is applied to the scan line S. Referring to FIG.

Scan signals are sequentially supplied to the scan lines S. The data signals are supplied to the data lines D in synchronization with the scan signals.

Each pixel 4 includes a light emitting element LED, and a pixel circuit 2 connected to the data line D and the scanning line S to emit light of the light emitting element LED.

The anode electrode of the light emitting element LED is connected to the pixel circuit 2, and the cathode electrode is connected to the second power source VSS. Such a light emitting device (LED) generates light corresponding to the current supplied from the pixel circuit (2).

The pixel circuit 2 is provided between the second transistor M2 connected between the first power supply VDD and the light emitting element LED, and between the second transistor M2, the data line D, and the scan line S. And a storage capacitor C connected between the first and second transistors M1 and the gate and source electrodes of the second transistor M2.

The gate electrode of the first transistor M1 is connected to the scan line S, and the source electrode is connected to the data line D. The drain electrode of the first transistor M1 is connected to one terminal of the storage capacitor C. The first transistor M1 is turned on when the scan signal is supplied from the scan line S to supply the data signal supplied from the data line D to the storage capacitor C. At this time, the storage capacitor C is charged with a voltage corresponding to the data signal.

The gate electrode of the second transistor M2 is connected to one terminal of the storage capacitor C, and the source electrode is connected to the other terminal of the storage capacitor C and the first power supply VDD. The drain electrode of the second transistor M2 is connected to the anode electrode of the light emitting element LED. The second transistor M2 controls the amount of current flowing from the second power supply VDD to the light emitting device LED in response to the voltage value stored in the storage capacitor C. In this case, the organic light emitting diode LED generates light having a luminance 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 light emitting display cannot display an image of uniform luminance. In detail, the threshold voltages of the second transistors M2 included in the pixels 4 are set differently for each of the pixels 4 due to a process deviation or the like. As described above, when the threshold voltages of the second transistor M2 are set differently, even when data signals corresponding to the same grayscale are supplied to the plurality of pixels 4, the threshold voltages of the second transistor M2 are mutually different. Light of different luminance is produced in the light emitting element (LED).

Accordingly, an object of the present invention is to provide a pixel, a light emitting display, and a driving method thereof, which can display an image of uniform brightness and reduce the load of a scan driver.

In order to achieve the above object, the first aspect of the present invention provides a diode-connected first transistor so that forward bias is applied when an initialization voltage is supplied from a data line, and a current corresponding to the data signal supplied to the data line. And a second transistor for outputting, wherein the initialization voltage emits light corresponding to the current supplied from the pixel circuit and the pixel circuit supplied to the gate terminal of the second transistor via the first transistor. It provides a pixel having a light emitting device for.

Preferably, a storage capacitor connected to the second transistor to charge a voltage corresponding to the data signal, and the initialization voltage connected to the data line and the scan line and supplied from the data line when a scan signal is supplied from the scan line. And a third transistor for transmitting a data signal to the second transistor, and a fourth transistor connected to the second transistor to connect the second transistor in the form of a diode when the scan signal is supplied. And the initialization voltage is supplied to the gate terminal of the second transistor via the fourth transistor.

The second aspect of the present invention provides an image display unit including a plurality of scan lines, a plurality of data lines, and a plurality of pixels, a scan driver for sequentially supplying scan signals to the plurality of scan lines, and a period in which the scan signals are supplied. And a data driver for supplying an initialization voltage and a data signal to the day line, each pixel including at least one first transistor diode-connected such that a forward bias is applied when the initialization voltage is supplied. Provide the device.

Preferably, each of the pixels includes a light emitting device, a second transistor for controlling a current supplied to the light emitting device in response to the data signal, and a voltage connected to the second transistor to charge a voltage corresponding to the data signal. And a third transistor connected to the scan line and the data line to transfer the initialization voltage and the data signal to the second transistor.

According to a third aspect of the present invention, there is provided a method of sequentially supplying a scan signal to a plurality of scan lines, supplying an initialization voltage to data lines during a first period of time during which the scan signal is supplied, and supplying the scan signal. Providing a data signal to data lines during a second period except for the first period of the period, and generating light corresponding to the data signal in the light emitting device; do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 8 that can be easily implemented by those skilled in the art.

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

Referring to FIG. 2, the pixel 40 according to the first embodiment of the present invention is connected to a light emitting element LED, a data line D, a scanning line S, and a light emission control line E so as to emit light. A pixel circuit 42 for emitting LEDs).

The anode electrode of the light emitting element LED is connected to the pixel circuit 42, and the cathode electrode is connected to the second power source VSS. Such a light emitting device (LED) generates light corresponding to the current supplied from the pixel circuit 42.

The pixel circuit 42 includes first to sixth transistors M1 to M6 and a storage capacitor C.

The sixth transistor M6 is turned on when the scan signal is supplied to the n−1 th scan line Sn−1. When the sixth transistor M6 is turned on, the scan signal supplied to the n-1 th scan line Sn-1 is supplied to the gate terminal of the first transistor M1 and one end of the storage capacitor C. In this case, the gate terminal and the storage capacitor C of the first transistor M1 are initialized to a voltage corresponding to the scan signal.

When the scan signal is supplied to the nth (n is a natural number) scan line Sn, the second transistor M2 supplies a data signal supplied to the data line D to the first node N1. The third transistor M3 is turned on when the scan signal is supplied to the nth (n is a natural number) scan line Sn to connect the first transistor M1 in the form of a diode.

When the first transistor M1 is connected in the form of a diode, the data signal applied to the first node N1 is transmitted through the first transistor M1 and the third transistor M3 through the first transistor M1 and the storage capacitor. It is supplied to one side of C). Here, since the gate terminal voltage of the first transistor M1 is set to a low voltage corresponding to the scan signal supplied to the n-th scan line Sn-1, the data signal applied to the first node N1 is applied. The first transistor M1 may be turned on.

When a data signal is supplied to one side of the storage capacitor C, the storage capacitor C is charged with a voltage corresponding to the data signal.

The fourth and fifth transistors M4 and M5 are turned on when the emission control signal is not supplied from the emission control line E. When the fourth and fifth transistors M4 and M5 are turned on, current corresponding to the voltage charged in the storage capacitor C is supplied to the light emitting device LED through the first transistor M1. Then, light corresponding to the current supplied to the light emitting device (LED) is generated.

In the pixel 40 according to the first exemplary embodiment of the present invention, since the data signal is applied to the capacitor C through the first transistor M1 and the third transistor M3, the threshold of the first transistor M1 is increased. The voltage may be compensated for itself to store a voltage corresponding to the data signal in the storage capacitor C regardless of the threshold voltage of the first transistor M1. Therefore, when the pixel according to the first embodiment of the present invention is used, a uniform image can be displayed regardless of the variation of the manufacturing process.

The current flowing from the pixel according to the first embodiment of the present invention to the light emitting device (LED) can be represented by Equation 1 and Equation 2.

I _LED = β / 2 (V _GS -V _TH ) ²

I _LED = β / 2 {(V _DD -V _DATA + V _TH )-V _TH } ² = β / 2 (V _DD -V _DATA ) ²

In Equations 1 and 2, I _LED is a current flowing through the light emitting device (LED), V _GS is a voltage between the gate and the source of the first transistor M1, V _TH is the threshold voltage of the first transistor M1, and β represents a constant.

Referring to equations (1) and (2), regardless of the threshold voltage of the first transistor M1, the current corresponding to the data signal flows into the light emitting device LED.

However, the pixel 40 according to the first embodiment of the present invention has a problem that a high load is applied to a scan driver not shown. In detail, the scan signal supplied from the scan driver to the n-1 th scan line Sn-1 is supplied to the pixels 40 formed on the n-1 horizontal line and the n horizontal line. Here, the sixth transistor M6 of the pixels 40 connected to the n horizontal line is turned on by the scan signal supplied to the n−1 th scan line Sn−1 to perform an initialization operation. The second transistor M2 of the pixels 40 connected to the n−1 horizontal line is turned on by the scan signal supplied to the n−1 th scan line Sn to supply a data signal. That is, in the pixel according to the first embodiment of the present invention, since the scan signal supplied to one scan line S is supplied to the pixels 40 positioned on two horizontal lines, a high load is applied to the scan driver.

In particular, the load applied to the scan driver is further increased as the image display portion becomes larger in area and higher resolution. In fact, the light emitting display device employing the pixel 40 shown in Fig. 2 is difficult to implement a large area and a high resolution image display part by load applied to the scan driver.

3 is a diagram illustrating a light emitting display device according to an exemplary embodiment of the present invention. 4 is a diagram illustrating a driving waveform supplied from a scan driver and a data driver.

3 and 4, a light emitting display device according to an exemplary embodiment of the present invention includes an image display unit including pixels 140 formed in an intersection area of scan lines S1 to Sn and data lines D1 to Dm. 130, a scan driver 110 for driving the scan lines S1 to Sn, a data driver 120 for driving the data lines D1 to Dm, a scan driver 110 and a data driver And a timing controller 150 for controlling the 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 generates a scan signal and sequentially supplies the generated scan signal to the scan lines S1 to Sn as shown in FIG. 4. In addition, the scan driver 110 generates the emission control signal EMI in response to the scan driving control signals SCS, and sequentially supplies the generated emission control signals to the emission control scenes E1 to En. Here, the width of the emission control signal EMI is set equal to or wider than the width of the scan signal.

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 an initialization voltage V1 and a data signal DS, and generates the initialization voltage V1 and the data signal DS in the data lines D1. To Dm).

In detail, the data driver 120 supplies the initialization voltage V1 to the data lines D1 to Dm during the first period L1 when the scan signal is supplied. The data driver 120 supplies the data signal DS to the data lines D1 to Dm during the second period L2 following the first period L1. Here, the second period L2 is set equal to or wider than the first period L1 so that the data signal DS can be supplied to the pixels 140 for a sufficient time.

On the other hand, when the pixels 140 are formed of a P-type MOSFET, the initialization voltage V1 is set lower than the voltage of the lowest data signal that can be supplied from the data driver 120. For example, if a data signal of 2V to 4V is supplied from the data driver 120, the initialization voltage V1 is set lower than 2V. When the pixels 140 are formed of N-type MOSFETs, the initialization voltage V1 is set higher than the voltage of the highest data signal that can be supplied from the data driver 120. For example, if a data signal of 2V to 4V is supplied from the data driver 120, the initialization voltage V1 is set higher than 4V.

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 image display unit 130 receives the first power source VDD and the second power source VSS from the outside. Here, the first power source VDD and the second power source VSS are supplied to the respective pixels 140. Each of the pixels 140 generates light corresponding to the data signal DS. In addition, the emission time of the pixels 140 is controlled in response to the emission control signal.

5 is a circuit diagram illustrating a structure of a pixel according to a second exemplary embodiment of the present invention.

Referring to FIG. 5, each of the pixels 142 according to the second embodiment of the present invention is connected to a light emitting element LED, a data line D, a scan line S, and a light emission control line E to emit light. The pixel circuit 142 for emitting the device LED is provided.

The anode electrode of the light emitting element LED is connected to the pixel circuit 142, and the cathode electrode is connected to the second power source VSS. The second power source VSS may be a voltage lower than the first power source VDD, for example, a ground voltage. The light emitting device LED generates light corresponding to a current supplied from the pixel circuit 142. To this end, the light emitting device (LED) is formed of an organic material including fluorescent and / or phosphorescent.

The pixel circuit 142 includes at least one first transistor M1 connected in the form of a diode to be turned on when the initialization voltage V1 is supplied from the data driver 120. The pixel circuit 142 is electrically connected to one scan line Sn.

The pixel circuit 142 may include a third transistor M3 and a fifth transistor M5 connected between the first power supply VDD and the data line D, the light emitting element LED, and the light emission control line En. 6th transistor (M6) connected to the (6), the first transistor (M1) and the second transistor (M2) and the second transistor (M2) connected between the sixth transistor (M6) and the first node (N1) And a fourth transistor M4 connected between the gate terminal and the second terminal. Here, the second terminal means any one of a source terminal and a drain terminal.

The first terminal of the second transistor M2 is connected to the first node N1. Here, if the first terminal is different from the second terminal, for example, the second terminal is the source terminal, the first terminal is set as the drain terminal, and if the second terminal is the drain terminal, the first terminal is set as the source terminal. . The second terminal of the second transistor M2 is connected to the first terminal of the sixth transistor M6 and the gate terminal of the second transistor M2 is connected to the storage capacitor C. The second transistor M2 supplies a current corresponding to the voltage charged in the storage capacitor C to the light emitting device LED.

The gate terminal and the second terminal of the first transistor M1 are connected to the first node N1, and the first terminal is connected to the second terminal of the second transistor M2. The first transistor M1 is turned on by applying a forward bias when the initialization voltage V1 is applied to the first node N1. When the first transistor M1 is turned on, the initialization voltage V1 is supplied to the gate terminal of the second transistor M2 via the fourth transistor M4, and thus the gate terminal of the second transistor M2. And the storage capacitor C is initialized.

The second terminal of the fourth transistor M4 is connected to the gate terminal of the second transistor M2, and the first terminal is connected to the second terminal of the second transistor M2. The gate terminal of the fourth transistor M4 is connected to the nth scan line Sn. The fourth transistor M4 is turned on when the scan signal is supplied to the nth scan line Sn to connect the second transistor M2 in the form of a diode.

The first terminal of the third transistor M3 is connected to the data line D, and the second terminal is connected to the first node N1. The gate terminal of the third transistor M3 is connected to the nth scan line Sn. When the scan signal is supplied to the nth scan line Sn, the third transistor M3 is turned on to supply the initialization voltage V1 and the data signal DS supplied to the data line D. It is supplied to N1).

The second terminal of the fifth transistor M5 is connected to the first node N1, and the first terminal is connected to the first power source VDD. The gate terminal of the fifth transistor M5 is connected to the light emission control line En. The fifth transistor M5 is turned on when the emission control signal EMI is not supplied to electrically connect the first power source VDD and the first node N1.

The first terminal of the sixth transistor M6 is connected to the second terminal of the second transistor M2, and the second terminal is connected to the light emitting element LED. The gate terminal of the sixth transistor M6 is connected to the light emission control line En. The sixth transistor M6 is turned on when the emission control signal EMI is not supplied to supply the current supplied from the second transistor M2 to the light emitting device LED.

The operation of the pixel 142 will be described in detail with reference to FIG. 4. First, a scan signal is supplied to the nth scan line Sn, and an initialization voltage V1 is supplied to the data lines D. The emission control signal EMI is supplied to the nth emission control line En so that the fifth transistor M5 and the sixth transistor M5 are turned off.

When the scan signal is supplied to the nth scan line Sn, the third transistor M3 and the fourth transistor M4 are turned on. When the third transistor M3 is turned on, the initialization voltage V1 supplied to the data lines D is supplied to the first node N1. The initialization voltage V1 supplied to the first node N1 is supplied to the first terminal of the fourth transistor M4 via the first transistor M1 connected in the form of a diode. Here, since the fourth transistor M4 is turned on, the initialization voltage V1 is supplied to the gate terminal of the second transistor M2.

When the initialization voltage V1 is supplied to the gate terminal of the second transistor M2, the gate terminal and the storage capacitor C of the second transistor M2 are initialized. In other words, the gate terminal of the second transistor M2 is initialized by the initialization voltage V1 having a lower voltage value than the data signal of the lowest voltage that can be supplied from the data driver 120. Then, the second transistor M2 may be turned on regardless of the voltage value of the data signal applied to the first node N1.

After the initialization voltage V1 is supplied to the gate terminal of the second transistor M2, the data signal DS corresponding to the predetermined gray level is supplied to the data line D. The data signal DS supplied to the data line D is applied to the first node N1 via the third transistor M3. At this time, since the gate terminal voltage of the second transistor M2 is initialized by the initialization voltage V1, the second transistor M2 is turned on. When the second transistor M2 is turned on, the data signal applied to the first node N1 is supplied to one side of the storage capacitor C via the second transistor M2 and the fourth transistor M4. At this time, the storage capacitor C is charged with a voltage corresponding to the data signal.

Thereafter, the supply of the emission control signal EMI supplied to the nth emission control line En is stopped to turn on the fifth transistor M5 and the sixth transistor M6. When the fifth transistor M5 and the sixth transistor M6 are turned on, a current corresponding to the voltage charged in the storage capacitor C is supplied to the light emitting device LED through the second transistor M2. Accordingly, the light corresponding to the data signal DS is generated in the light emitting device LED.

In the present invention as described above, the gate terminal of the second transistor M2 included in the pixels 140 is initialized using the initialization voltage V1 supplied from the data line D. Accordingly, in the present invention, each pixel 140 is connected to one scan line S, thereby reducing the load of the scan driver 110. In other words, the scan signal supplied to the n-1 th scan line Sn-1 from the pixel 40 shown in FIG. 2 is supplied to the pixels formed on the n-1 horizontal line and the n horizontal line. The scan signal supplied to the n-1 th scan line Sn-1 is supplied only to the pixels 140 formed on the n-1 horizontal line. Accordingly, in the present invention, the load of the scan driver 110 can be reduced, thereby realizing a large area and high resolution light emitting display device. In addition, in the present invention, an image of uniform luminance may be displayed regardless of the threshold voltage of the second transistor M2.

Meanwhile, in the present invention, the first transistor M1 shown in FIG. 5 is turned on when the initialization voltage V1 is applied to the data line D so that the gate terminal of the second transistor M2 can be initialized. It can be applied in various forms. For example, the first transistor M1 may be connected as shown in FIG. 6.

Referring to FIG. 6, the gate terminal and the second terminal of the first transistor M1 are connected to the first node N1, and the first terminal is connected to the gate terminal of the second transistor M2. As described above, even if the first terminal of the first transistor M1 is connected to the gate terminal of the second transistor M2, the operation process is the same. However, in the pixel illustrated in FIG. 5, the initialization voltage V1 applied to the first node N1 is a gate terminal of the second transistor M2 via the first transistor M1 and the fourth transistor M4. Although supplied, the initialization voltage V1 applied to the first node N1 is supplied to the gate terminal of the second transistor M2 via the first transistor M1 in the pixel illustrated in FIG. 6. In other operations, the pixels shown in FIGS. 5 and 6 are the same.

Meanwhile, although the pixel 140 is illustrated as a P-type MOSFET in FIG. 5, the pixel 140 may be implemented as an N-type MOSFET as shown in FIG. 7. If the pixel 140 and the N-type MOSFET are implemented, the polarity of the driving waveform shown in FIG. 4 is reversed, but the operation process is the same.

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

Referring to FIG. 8, the pixel 200 according to the third embodiment of the present invention includes a light emitting device (LED) and a pixel circuit 202.

The anode electrode of the light emitting element LED is connected to the pixel circuit 202, and the cathode electrode is connected to the second power source VSS. The second power source VSS may be a voltage lower than the first power source VDD, for example, a ground voltage. The light emitting device LED generates light corresponding to a current supplied from the pixel circuit 142. To this end, the light emitting device (LED) is formed of an organic material including fluorescent and / or phosphorescent.

The pixel circuit 202 includes at least one first transistor M1 connected in the form of a diode to be turned on when the initialization voltage V1 is supplied from the data driver 120. The pixel circuit 202 is electrically connected to one scan line Sn.

The pixel circuit 202 includes a third transistor M3 connected to the data line D and the scan line Sn, a second transistor M2 connected between the first power supply VDD and the light emitting element LED, and A gate terminal of the first transistor M1 and the fourth transistor M4 and the second transistor M2 connected between the fifth transistor M5, the third transistor M3, and the second transistor M2; A storage capacitor C is connected between the first power supply VDD.

The first terminal of the second transistor M2 is connected to one end of the first power supply VDD and the storage capacitor C, and the gate terminal is connected to the other end of the storage capacitor C. The second terminal of the second transistor M2 is connected to the first terminal of the fifth transistor M5. The second transistor M2 supplies a current corresponding to the voltage charged in the storage capacitor C to the light emitting device LED.

The first terminal of the fifth transistor M5 is connected to the second terminal of the second transistor M2, and the gate terminal is connected to the emission control line En. The second terminal of the fifth transistor M5 is supplied to the light emitting device LED. The fifth transistor M5 is turned on when the emission control signal EMI is not supplied to supply the current supplied from the second transistor M2 to the light emitting device LED.

The first terminal of the third transistor M3 is connected to the data line D, and the second terminal is connected to the first node N1. The gate terminal of the third transistor M3 is connected to the nth scan line Sn. When the scan signal is supplied to the nth scan line Sn, the third transistor M3 is turned on to supply the initialization voltage V1 and the data signal DS supplied to the data line D. It is supplied to N1).

The gate terminal and the second terminal of the first transistor M1 are connected to the first node N1, and the first terminal is connected to the second terminal of the fourth transistor M4. The first transistor M1 is turned on with a forward bias applied when the initialization voltage V1 is applied via the third transistor M3. When the first transistor M1 is turned on, the initialization voltage V1 is supplied to the gate terminal of the second transistor M2, the gate terminal of the fourth transistor M4, and the storage capacitor C. Accordingly, the second transistor M1 is turned on. The gate terminal of the transistor M2, the gate terminal of the fourth transistor M4, and the storage capacitor C are initialized.

The first terminal of the fourth transistor M4 is connected to the first node N1, and the second terminal is connected to its gate terminal. That is, the fourth transistor M4 is connected in the form of a diode. The fourth transistor M4 is turned on when the data signal DS is supplied via the third transistor M3 to supply the data signal DS to the storage capacitor C.

The operation of the pixel 200 will be described in detail with reference to FIG. 4. First, a scan signal is supplied to the nth scan line Sn, and an initialization voltage V1 is supplied to the data lines D. The emission control signal EMI is supplied to the nth emission control line En so that the fifth transistor M5 is turned off.

When the scan signal is supplied to the nth scan line Sn, the third transistor M3 is turned on. When the third transistor M3 is turned on, the initialization voltage V1 supplied to the data lines D is supplied to the first node N1. The initialization voltage V1 supplied to the first node N1 is the gate terminal of the second transistor M2 and the gate of the fourth transistor M4 via the first transistor M1 connected in the form of a diode. Supply to terminal and storage capacitor (C).

Here, the gate terminal of the second transistor M2, the gate terminal of the fourth transistor M4, and the storage capacitor C are initialized by the initialization voltage V1. In other words, the gate terminal of the second transistor M2 and the fourth transistor M4 by the initialization voltage V1 having a voltage value lower than that of the lowest voltage data signal that can be supplied from the data driver 120. The gate terminal and the storage capacitor C are initialized. Then, the fourth transistor M4 may be turned on regardless of the voltage value of the data signal applied to the first node N1.

Thereafter, the data signal DS corresponding to the predetermined gray level is supplied to the data line D. FIG. The data signal DS supplied to the data line D is applied to the first node N1 via the third transistor M3. At this time, since the gate terminal voltage of the fourth transistor M4 is initialized by the initialization voltage V1, the fourth transistor M4 is turned on. When the fourth transistor M4 is turned on, the data signal applied to the first node N1 is supplied to the gate terminal via the second terminal of the fourth transistor M4. At this time, the storage capacitor C is charged with a voltage corresponding to the data signal.

Thereafter, the supply of the emission control signal EMI supplied to the nth emission control line En is stopped, and the fifth transistor M5 is turned on. When the fifth transistor M5 is turned on, a current corresponding to the voltage charged in the storage capacitor C is supplied to the light emitting device LED through the second transistor M2, and thus the light emitting device LED In the light corresponding to the data signal DS is generated.

In the present invention as described above, the gate terminal of the second transistor M2 included in the pixels 200, the gate terminal of the fourth transistor M4, and the storage are stored using the initialization voltage V1 supplied from the data line D. Initialize the capacitor (C). Therefore, in the present invention, each pixel 200 is connected to one scan line S, thereby reducing the load of the scan driver 110. In other words, the scan signal supplied to the n-1 th scan line Sn-1 from the pixel 40 shown in FIG. 2 is supplied to the pixels formed on the n-1 horizontal line and the n horizontal line. The scan signal supplied to the n-1 th scan line Sn-1 is supplied only to the pixels 200 formed on the n-1 horizontal line. Accordingly, in the present invention, the load of the scan driver 110 can be reduced, thereby realizing a large area and high resolution light emitting display device.

The above detailed description and drawings are merely exemplary of the present invention, which 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 claims or the 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 light emitting display device and the driving method thereof according to the exemplary embodiment of the present invention, the initialization voltage and the data signal are continuously supplied to the data line every time the scan signal is supplied, and the pixel is normally operated using the initialization voltage. The pixel can be initialized so that it can be obtained. As such, when the pixel is initialized using the initialization voltage supplied to the data line, the load of the scan driver may be reduced, thereby realizing a light emitting display device having a large area and a high resolution.

Claims (24)

And a first transistor diode-connected to apply forward bias when the initialization voltage is supplied from the data line, and a second transistor for outputting a current corresponding to the data signal supplied to the data line, wherein the initialization voltage is the first transistor. A pixel circuit supplied to the gate terminal of the second transistor via a transistor; And a light emitting device for emitting light corresponding to the current output from the pixel circuit. The method of claim 1, A storage capacitor connected to the second transistor to charge a voltage corresponding to the data signal; A third transistor connected to the data line and the scan line to transfer the initialization voltage and the data signal supplied from the data line to the second transistor when a scan signal is supplied from the scan line; And a fourth transistor connected to the second transistor to connect the second transistor in the form of a diode when the scan signal is supplied. The method of claim 2, And the initialization voltage is supplied to the gate terminal of the second transistor via the fourth transistor. The method of claim 2, And a voltage value of the initialization voltage is set such that the second transistor is turned on when the data signal is supplied. The method of claim 2, And at least one transistor connected to a light emission control line for controlling a supply time of a current supplied from the pixel circuit to the light emitting element. The method of claim 1, A storage capacitor connected to the second transistor to charge a voltage corresponding to the data signal; A third transistor connected to the data line and the scan line to transfer the initialization voltage and the data signal supplied from the data line to the second transistor when a scan signal is supplied from the scan line; And a fourth transistor connected between the third transistor and the second transistor and connected in a diode form to transfer the data signal to the second transistor. The method of claim 6, And a voltage value of the initialization voltage is set such that the fourth transistor is turned on when the data signal is supplied. The method of claim 6, And at least one transistor connected to a light emission control line for controlling a supply time of a current supplied from the pixel circuit to the light emitting element. An image display unit including a plurality of scanning lines, a plurality of data lines, and a plurality of pixels; A scan driver for sequentially supplying scan signals to the plurality of scan lines; A data driver for supplying an initialization voltage and a data signal to the day line every time the scan signal is supplied; And each pixel comprises at least one first transistor diode-connected such that a forward bias is applied when the initialization voltage is supplied. The method of claim 9, Each of the pixels A light emitting element, A second transistor for controlling a current supplied to the light emitting element in response to the data signal; A storage capacitor connected to the second transistor to charge a voltage corresponding to the data signal; And a third transistor connected to the scan line and the data line to transfer the initialization voltage and the data signal to the second transistor. The method of claim 10, Each of the pixels And a fourth transistor connected between the gate terminal and the second terminal of the second transistor to connect the second transistor in the form of a diode when the scan signal is supplied. The method of claim 11, And the first transistor is turned on when the initialization voltage is supplied to supply the initialization voltage to the gate terminal of the second transistor via the fourth transistor. The method of claim 11, And the first transistor is turned on when the initialization voltage is supplied to supply the initialization voltage to a gate terminal of the second transistor. The method of claim 10, Each of the pixels And a fourth transistor having a first terminal connected to a second terminal of the third transistor, and a gate terminal and a second terminal connected to a gate terminal of the second transistor. The method of claim 10, The first transistor and the second transistor are formed of a P-type transistor. The method of claim 15, And the initialization voltage is set lower than a voltage of the lowest data signal that can be supplied from the data driver. The method of claim 10, And the first transistor and the second transistor are formed of an N-type transistor. The method of claim 17, And the initialization voltage is set higher than a voltage of the highest data signal that can be supplied from the data driver. The method of claim 9, And a supply period of the data signal is set equal to or longer than the initialization voltage supply period. Sequentially supplying scan signals to a plurality of scan lines; Supplying an initialization voltage to data lines during a first period of time during which the scan signal is supplied; Supplying a data signal to data lines for a second period except the first period during the period in which the scan signal is supplied; And generating light corresponding to the data signal in the light emitting device. The method of claim 20, When the initialization voltage is supplied to the data lines, a first transistor included in each of the pixels is diode-connected to supply the initialization voltage to a gate terminal of a second transistor for controlling the amount of current supplied to the light emitting device. Method of driving a light emitting display device. The method of claim 21, And the initialization voltage is set lower than the voltage of the data signal when the first transistor is formed of a P-type transistor. The method of claim 21, And the initialization voltage is set higher than the voltage of the data signal when the first transistor is formed of an N-type transistor. The method of claim 20, And the second period is set equal to or wider than the first period.

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