KR100688819B1 - Light Emitting Display and Driving Method Thereof - Google Patents

Abstract

The present invention relates to a light emitting display device capable of reducing power consumption.

The light emitting display device of the present invention includes a plurality of scanning lines and data lines and a plurality of pixels for controlling the amount of current flowing from the first power supply to the second power supply via the light emitting element in response to the data signals supplied to the data lines. An image display unit, a data driver for supplying a data signal to the data lines, and a scan driver for sequentially supplying a scan signal to the scan lines, wherein the swing width of the scan signal supplied to the scan lines is The voltage fluctuation range is set to be lower than the voltage difference between the first voltage and the second voltage.

Description

Light Emitting Display and Driving Method Thereof             

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

FIG. 2 is a diagram illustrating a scan signal supplied to the scan line shown in FIG. 1.

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

FIG. 4 is a diagram illustrating a scan signal supplied from the scan driver shown in FIG. 3.

FIG. 5 is a diagram illustrating an embodiment of a pixel illustrated in FIG. 3.

FIG. 6 is a diagram illustrating a scan signal supplied to a scan line of the pixel illustrated in FIG. 5.

7 is a diagram illustrating a light emitting display device according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 7.

9 is a diagram illustrating a driving waveform supplied to the pixel of FIG. 8.

FIG. 10 is a diagram illustrating a second embodiment of the pixel illustrated in FIG. 7.

FIG. 11 is a diagram illustrating a driving waveform supplied to the pixel of FIG. 10.

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

4: pixel 2,212: pixel circuit

110,200: scan driver 120: data driver

130: image display unit 140,210: pixel

150: timing controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting display device and a driving method thereof, and more particularly, to a light emitting display device and a driving method thereof which can reduce power consumption.

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 emits light from a light emitting device by supplying a current corresponding to the data signal to the light emitting device using a transistor formed for each pixel.

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

Referring to FIG. 1, a pixel 4 of a conventional light emitting display device is connected to a light emitting device OLED, a data line Dm, and a scanning line Sn to control a light emitting device OLED 2. ).

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

The pixel circuit 2 controls the amount of current supplied to the light emitting element 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 VDD and the light emitting element OLED, the second transistor M2, the data line Dm, and the scan line Sn. And a storage capacitor C connected between the first electrode M1 and the gate electrode of the second transistor M2 and the first electrode.

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 C. 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, and the storage capacitor C ). In this case, the storage capacitor C 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 C, and the first electrode is connected to the other terminal of the storage capacitor C and the first power supply VDD. The second electrode of the second transistor M2 is connected to the anode electrode of the light emitting element OLED. The second transistor M2 controls the amount of current flowing from the first power supply VDD to the light emitting device OLED in response to the voltage value stored in the storage capacitor C. FIG. In this case, the light emitting device OLED generates light corresponding to the amount of current supplied from the second transistor M2.

In the conventional light emitting display device driven as described above, the scan signals are sequentially supplied to the scan lines S. FIG. Here, the pixel 4 receives the data signal while the scan signal is supplied to the scan lines S, and the pixel 4 emits light corresponding to the data signal during the period when the scan signal is not supplied. Therefore, the voltage value of the scan signal supplied to the scan lines S so that the data signal can be written is set such that the first transistor M1 is turned on. Then, the voltage value supplied to the scan lines S during the period in which the scan signal is not supplied so that the written data signal can be maintained is set such that the first transistor M1 is turned off.

In practice, conventionally, the voltage of the second power source VSS is supplied as the scan signal as shown in FIG. 2, and the voltage of the first power source VDD is supplied during the rest of the period (in this case, the first transistor M1). Here, the first power source VDD and the second power source VSS are power supplies used to supply current to the light emitting device OLED, and have a high voltage difference (for example, 10V or more). Have Therefore, when the scan signal having the voltage difference between the first power source VDD and the second power source VSS is supplied to the scan line S, the voltage fluctuation range (swing width) of the scan line S is set to be large, and accordingly high consumption The problem of power consumption occurs. In addition, since the first power supply VDD and the second power supply VSS have a voltage difference greater than or equal to a predetermined voltage, circuits such as an amplifier are additionally installed in the scan driver and the like, thereby causing a problem in that the manufacturing cost increases.

Accordingly, an object of the present invention is to provide a light emitting display device and a driving method thereof capable of reducing power consumption.

In order to achieve the above object, the first aspect of the present invention is to control the amount of current flowing from the first power source to the second power source via the light emitting element in response to a plurality of scan lines and data lines and data signals supplied to the data lines. An image display unit having a plurality of pixels, a data driver for supplying a data signal to the data lines, and a scan driver for sequentially supplying a scan signal to the scan lines; A swing width of a scan signal is provided to have a voltage fluctuation range lower than a voltage difference between the first voltage and the second voltage.

Preferably, when the scan signal is supplied, a voltage between the first power source and the second power source is supplied to the scan line. A transistor included in each of the pixels and turned on in response to the scan signal is set to a PMOS type. The scan driver supplies the first power to turn off the transistor for a period other than a period during which the scan signal is supplied to the scan line.

According to a second aspect of the present invention, there is provided a method of sequentially supplying scan signals to scan lines, supplying data signals to data lines when the scan signals are supplied, and first power sources corresponding to the data signals in pixels. And controlling the amount of current supplied to the second power supply via the light emitting element from the light emitting device, wherein the swing width of the scan signal is set to have a voltage fluctuation range lower than the voltage difference between the first voltage and the second voltage. It provides a method of driving a device.

Preferably, when the scan signal is supplied, a voltage between the first power source and the second power source is supplied to the scan line. When the transistor included in each of the pixels and connected to the scan line is set to PMOS, the first power is supplied to the scan line such that the transistor is turned off for a period other than a period during which the scan signal is supplied. Supplied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 3 to 11 which can be easily implemented by those skilled in the art.

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

Referring to FIG. 3, the light emitting display device according to the first embodiment of the present invention includes pixels 140 formed in an area partitioned by scan lines S1 to Sn and data lines D1 to Dm. The image display unit 130, the scan driver 110 for driving the scan lines S1 to Sn, the data driver 120 for driving the data lines D1 to Dm, the scan driver 110 and the data. A timing controller 150 is provided to control the driver 120.

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 and supplies the same to the pixels 140. Each of the pixels 140 supplied with the first power source VDD and the second power source VSS receives the first power source VDD and the second power source VSS from the first power source VDD to the second power source VSS via the light emitting device OLED. By controlling the flowing current, light corresponding to the data signal is generated. Here, the structure of the pixel 140 may be configured in various ways. For example, each of the pixels 140 may include two PMOS transistors M1 and M2 and one storage capacitor C as shown in FIG. 1.

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 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.

Here, the pixels 4 that receive the scan signal supplied from the scan driver 110 receive the data signal from the data line D. FIG. The pixels 4 that do not receive the scan signal from the scan driver 110 emit light corresponding to the data signal supplied in the previous period. Therefore, when each of the pixels 140 is configured as shown in FIG. 1, the scan driver 110 supplies a scan signal having a predetermined voltage value so that the first transistor M1 is turned on. In addition, the scan driver 110 supplies the scan lines S with a voltage value at which the first transistor M1 is turned off during the period in which the scan signal is not supplied.

In practice, the scan driver 110 supplies the first voltage VDD to the scan line S during the period in which the scan signal is not supplied. As described above, when the first voltage VDD is supplied to the scan line S, the first transistor M1 is stably turned off. In addition, the scan driver 110 supplies the third voltage V3 to the scan line S when the scan signal is supplied. When the third voltage V3 is supplied to the scan line S, the first transistor M1 is turned on.

Here, the voltage value of the third voltage V3 is set to a value between the first voltage VDD and the second voltage VSS. That is, in the present invention, the third voltage V3 between the first voltage VDD and the second voltage VSS is supplied as the scan signal. For example, the third voltage V3 may be set to an intermediate voltage value between the first voltage VDD and the second voltage VSS. As such, when the third voltage V3 is supplied as the scan signal from the scan driver 110, power consumption can be reduced as compared with the conventional art. In other words, in the present invention, the scan line S has a voltage value variation range set between the first voltage VDD and the third voltage V3, thereby reducing power consumption. In fact, assuming that the third voltage V3 is a voltage located at half between the first voltage VDD and the second voltage VSS, the power consumed in the scan line S is less than 1/4 compared with the conventional art. Can be reduced.

On the other hand, when the third voltage V3 is supplied as the voltage (scan signal) for turning on the first transistor M1, the amount of current flowing decreases than when the second voltage VSS is supplied. However, even when the third voltage V3 is experimentally supplied, the current required for light emission of the light emitting device OLED is sufficiently supplied. Therefore, in the present invention, power consumption can be reduced without deterioration of image quality. Meanwhile, in the present invention, the pixel 140 may include two NMOS transistors M1 and M2 and one storage capacitor C as shown in FIG. 5. As such, when the pixel 140 is configured as an NMOS, the scan driver 110 supplies a scan signal as shown in FIG. 6.

5 and 6, the scan driver 110 may turn on the voltage (scan signal) or the voltage at which the first transistor M1 is turned on by the scan line S to drive the pixel 140. Should be supplied. To this end, the scan driver 110 supplies the first voltage VSS to the scan lines S when the scan signal is not supplied. When the first voltage VSS is supplied to the first transistor M1 composed of NMOS, the first transistor M1 is stably turned off when the scan signal is not supplied.

In addition, the scan driver 110 supplies the fourth voltage V4 to the scan lines S when the scan signal is supplied. Here, the fourth voltage V4 is set to a value between the first voltage VDD and the second voltage VSS. For example, the fourth voltage V4 may be set to an intermediate voltage value between the first voltage VDD and the second voltage VSS. As such, when the fourth voltage V4 is supplied to the scan lines S as the scan signal, the voltage variation range of the scan line S can be minimized, thereby reducing power consumption.

7 is a diagram illustrating a light emitting display device according to a second embodiment of the present invention. 7, the same components as those of FIG. 3 are assigned the same reference numerals, and detailed description thereof will be omitted.

Referring to FIG. 7, the light emitting display device according to the second embodiment of the present invention includes pixels 210 formed in regions partitioned by scan lines S1 to Sn and data lines D1 to Dm. The image display unit 130, the scan driver 200 for driving the scan lines S1 to Sn, the data driver 120 for driving the data lines D1 to Dm, the scan driver 200 and the data. A timing controller 150 is provided to control the driver 120.

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 200. 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 and supplies the same to the pixels 210. Each of the pixels 210 supplied with the first power supply VDD and the second power supply VSS is connected to the second power supply VSS from the first power supply VDD through the light emitting device OLED in response to the data signal. By controlling the flowing current, light corresponding to the data signal is generated. The emission time of the pixels 210 is set corresponding to the emission control signal supplied from the emission control line E. FIG. Here, each of the pixels 210 may be variously configured in a form including the emission control line E. FIG. For example, each of the pixels 210 may be configured as shown in FIG. 8. A detailed description of the pixel 210 illustrated in FIG. 8 will be described later.

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 scan driver 200 receives a scan driving control signal SCS from the timing controller 150. The scan driver 200 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. 9. The scan driver 200 generates the emission control signal EMI and sequentially supplies the generated emission control signal EMI to the emission control lines E. FIG.

The scan driver 200 according to the present invention scans the voltage of the first power source VDD so that the first transistor M1 is turned off stably when the scan signal is not supplied (turn-off voltage). ). When the scan signal is supplied (turn-on voltage), the scan driver 200 applies the third voltage V3, which is a value between the first voltage VDD and the second voltage VSS, to the scan lines S. FIG. Supply. Then, the voltage difference between the turn-off voltage and the turn-on voltage (scanning signal) supplied to the scan line S is set smaller than the voltage difference between the first voltage VDD and the second voltage VSS. Compared with this, the power consumption can be reduced.

When the emission control signal EMI is not supplied (turn-on voltage), the scan driver 200 supplies the third voltage V3 to the emission control lines E, and the emission control signal EMI is supplied. The first voltage VDD is supplied to the emission control lines E. Then, the voltage difference between the turn-on voltage and the turn-off voltage supplied to the light emission control lines E is set to be smaller than the voltage difference between the first voltage VDD and the second voltage VSS, thereby consuming less than the conventional voltage. You can save power.

FIG. 8 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 7.

Referring to FIG. 8, the pixel 210 according to the first embodiment of the present invention is connected to a light emitting element OLED, a data line Dm, and a scanning line Sn to control the light emitting element OLED. Circuit 212 is provided.

The anode electrode of the light emitting element OLED is connected to the pixel circuit 212, and the cathode electrode is connected to the second power source VSS. The light emitting device OLED generates predetermined light corresponding to the current supplied from the pixel circuit 212.

The pixel circuit 212 controls the amount of current supplied to the light emitting element OLED in response 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 212 may include a second transistor M2 and a third transistor M3 connected between the first power source VDD and the light emitting device OLED, a gate electrode of the second transistor M2, and the like. A storage capacitor C connected between the first electrode and a first transistor M1 positioned to be connected to the scan line Sn and the data line Dm.

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 C. The first transistor M1 is turned on when the scan signal is supplied from the scan line Sn to supply the data signal supplied from the data line Dm to the storage capacitor C. In this case, the storage capacitor C 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 C, and the first electrode is connected to the other terminal of the storage capacitor C and the first power supply VDD. The second electrode of the second transistor M2 is connected to the first electrode of the third transistor M3. The second transistor M2 controls the amount of current flowing from the first power supply VDD to the light emitting device OLED in response to the voltage value stored in the storage capacitor C. FIG.

The first electrode of the third transistor M3 is connected to the second electrode of the second transistor M2, and the second electrode is connected to the anode electrode of the light emitting device OLED. The gate electrode of the third transistor M3 is connected to the emission control line En. The third transistor M3 electrically connects the second transistor M2 and the light emitting element OLED when the emission control signal EMI is not supplied.

8 and 9, a scan signal having a voltage value of the third voltage V3 is supplied to the nth scan line Sn so that the first transistor M1 is turned on. . When the first transistor M1 is turned on, the data signal supplied from the data line Dm is supplied to the storage capacitor C via the first transistor M1. Then, the storage capacitor C is charged with a voltage corresponding to the data signal. After the voltage corresponding to the data signal is charged in the storage capacitor C, the second transistor M2 receives a current corresponding to the voltage charged in the storage capacitor C from the first power source VDD to the third transistor M3. To supply.

The emission control signal EMI having the voltage value of the first power supply VDD is supplied to the nth emission control line En during the period in which the scan signal is supplied to the nth scan line Sn. When the emission control signal EMI having the voltage value of the first power source VDD is supplied, the third transistor M3 is completely turned off to supply current from the second transistor M2 to the light emitting device OLED. To prevent them. After the supply of the scan signal to the nth scan line Sn is stopped, the voltage value of the third power source V3 is supplied to the nth emission control line En. Then, the third transistor M3 is turned on to electrically connect the second transistor M2 and the light emitting element OLED. In this case, the light emitting device OLED generates predetermined light corresponding to the current supplied from the second transistor M2.

Meanwhile, in the present invention, the structure of the pixel 210 may be variously set. For example, the pixel 210 of the present invention may be formed of an NMOS transistor as shown in FIG. 10.

FIG. 10 is a diagram illustrating a second embodiment of the pixel illustrated in FIG. 7.

Referring to FIG. 10, the pixel 210 according to the second exemplary embodiment of the present invention is configured as an NMOS, and the operation process thereof is the same as the pixel 210 according to the first exemplary embodiment shown in FIG. 8.

The scan driver 200 supplies a voltage (scan signal) and a voltage at which the first transistor M1 of the NMOS included in the pixel 140 is turned on. To this end, the scan driver 200 supplies the first voltage VSS to the scan lines S when the scan signal is not supplied. The first voltage VSS supplied to the scan lines S is supplied to the first transistor M1, so that the first transistor M1 is stably turned off.

In addition, the scan driver 200 supplies the fourth voltage V4 to the scan lines S when the scan signal is supplied. Here, the fourth voltage V4 is set to a voltage value between the first voltage VDD and the second voltage VSS. For example, the fourth voltage V4 may be set to an intermediate voltage value between the first voltage VDD and the second voltage VSS. As such, when the fourth voltage V4 is supplied as the scan signal, the voltage variation range of the scan line S can be minimized, thereby reducing power consumption.

Meanwhile, the scan driver 200 supplies the fourth voltage V4 to the emission control lines E when the emission control signal EMI is not supplied. When the fourth voltage V4 is supplied to the emission control line E, the third transistor M3 is turned on to electrically connect the light emitting element OLED and the second transistor M2. In this case, the second transistor M2 controls the current supplied from the first power source VDD to the second power source VSS via the light emitting device OLED.

The scan driver 200 supplies the second voltage VSS to the emission control line E when the emission control signal EMI is supplied. When the second voltage VSS is supplied to the emission control line E, the third transistor M3 is turned off to electrically isolate the light emitting device OLED and the second transistor M2.

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, a turn-on voltage (scanning signal) having a voltage variation range lower than the voltage difference between the first voltage and the second voltage supplied to the pixel. And turn-off voltage to the scan line. As such, when the turn-on voltage and the turn-off voltage having a low voltage variation range are supplied to the scan line, power consumption can be reduced as compared with the conventional art. In addition, when a voltage having a voltage fluctuation range lower than the voltage difference between the first voltage and the second voltage is supplied to the scan line, the circuit unit of the scan driver may be simply configured as compared with the conventional art, thereby reducing the manufacturing cost.

Claims (20)

A plurality of scan lines and data lines, An image display section including a plurality of pixels for controlling the amount of current flowing from the first power supply to the second power supply via the light emitting element in response to the data signal supplied to the data line; A data driver for supplying a data signal to the data lines; A scan driver for sequentially supplying scan signals to the scan lines; The swing width of the scan signal supplied to the scan lines is set to have a voltage fluctuation range lower than a voltage difference between the first voltage and the second voltage. The method of claim 1, And a voltage between the first power source and the second power source is supplied to the scan line when the scan signal is supplied. The method of claim 2, And a transistor included in each of the pixels and turned on in response to the scan signal, is configured to be a PMOS type. The method of claim 3, And the scan driver supplies the first power to turn off the transistor for a period other than a period during which the scan signal is supplied to the scan line. The method of claim 2, And a transistor included in each of the pixels and turned on in response to the scan signal, is configured as an NMOS type. The method of claim 5, And the scan driver supplies the second power to turn off the transistor for a period other than a period during which the scan signal is supplied to the scan line. The method of claim 1, And a light emission control line formed to be parallel to the scan line to control a light emission time of the pixel. The method of claim 7, wherein And the pixel includes at least one PMOS transistor connected to the light emission control line to control a time point of supplying current supplied to the light emitting device. The method of claim 8, The scan driver sequentially supplies a light emission control signal having a voltage value of the first power source to the light emission control lines, and between the first power source and the second power source for a period other than a period during which the light emission control signal is supplied. A light emitting display device for supplying a voltage to the light emitting control line. The method of claim 7, And the pixel includes at least one NMOS transistor connected to the emission control line to control a supply point of a current supplied to the light emitting element. The method of claim 10, The scan driver sequentially supplies a light emission control signal having a voltage value of the second power source to the light emission control lines, and between the first power source and the second power source for a period other than a period during which the light emission control signal is supplied. A light emitting display device for supplying a voltage to the light emitting control line. delete Sequentially supplying scan signals to scan lines; Supplying a data signal to data lines when the scan signal is supplied; Controlling the amount of current supplied from the first power source to the second power source via the light emitting element in response to the data signal in pixels; And a swing width of the scan signal is set to have a voltage fluctuation range lower than a voltage difference between the first voltage and the second voltage. The method of claim 13, And a voltage between the first power supply and the second power supply to the scan line when the scan signal is supplied. The method of claim 14, When the transistor included in each of the pixels and connected to the scan line is set to PMOS, the first power is supplied to the scan line such that the transistor is turned off for a period other than a period during which the scan signal is supplied. A method of driving a supplied light emitting display device. The method of claim 14, When the transistor included in each of the pixels and connected to the scan line is set to NMOS, the second power source is supplied to the scan line so that the transistor is turned off for a period other than a period during which the scan signal is supplied. A method of driving a supplied light emitting display device. The method of claim 13, And sequentially supplying emission control signals to emission control lines to control emission times of the pixels. The method of claim 17, When the transistor included in each of the pixels and connected to the emission control line is set to PMOS, the voltage value of the emission control signal is set to the voltage value of the first power source so that the transistor is turned off. Method of driving display device. The method of claim 17, When the transistor included in each of the pixels and connected to the emission control line is set to NMOS, the voltage value of the emission control signal is set to the voltage value of the second power supply so that the transistor is turned off. Method of driving display device. The method of claim 17, And a voltage value between the first power supply and the second power supply is supplied to the light emission control line during a period in which no light emission control signal is supplied to the light emission control line.

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